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[ceph.git] / ceph / src / civetweb / src / third_party / duktape-1.5.2 / src-separate / duk_js_executor.c

/*
 *  Ecmascript bytecode executor.
 */

#include "duk_internal.h"

/*
 *  Local declarations.
 */

DUK_LOCAL_DECL void duk__js_execute_bytecode_inner(duk_hthread *entry_thread, duk_size_t entry_callstack_top);

/*
 *  Arithmetic, binary, and logical helpers.
 *
 *  Note: there is no opcode for logical AND or logical OR; this is on
 *  purpose, because the evalution order semantics for them make such
 *  opcodes pretty pointless: short circuiting means they are most
 *  comfortably implemented as jumps.  However, a logical NOT opcode
 *  is useful.
 *
 *  Note: careful with duk_tval pointers here: they are potentially
 *  invalidated by any DECREF and almost any API call.  It's still
 *  preferable to work without making a copy but that's not always
 *  possible.
 */

DUK_LOCAL duk_double_t duk__compute_mod(duk_double_t d1, duk_double_t d2) {
        /*
         *  Ecmascript modulus ('%') does not match IEEE 754 "remainder"
         *  operation (implemented by remainder() in C99) but does seem
         *  to match ANSI C fmod().
         *
         *  Compare E5 Section 11.5.3 and "man fmod".
         */

        return (duk_double_t) DUK_FMOD((double) d1, (double) d2);
}

DUK_LOCAL void duk__vm_arith_add(duk_hthread *thr, duk_tval *tv_x, duk_tval *tv_y, duk_small_uint_fast_t idx_z) {
        /*
         *  Addition operator is different from other arithmetic
         *  operations in that it also provides string concatenation.
         *  Hence it is implemented separately.
         *
         *  There is a fast path for number addition.  Other cases go
         *  through potentially multiple coercions as described in the
         *  E5 specification.  It may be possible to reduce the number
         *  of coercions, but this must be done carefully to preserve
         *  the exact semantics.
         *
         *  E5 Section 11.6.1.
         *
         *  Custom types also have special behavior implemented here.
         */

        duk_context *ctx = (duk_context *) thr;
        duk_double_union du;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(ctx != NULL);
        DUK_ASSERT(tv_x != NULL);  /* may be reg or const */
        DUK_ASSERT(tv_y != NULL);  /* may be reg or const */
        DUK_ASSERT_DISABLE(idx_z >= 0);  /* unsigned */
        DUK_ASSERT((duk_uint_t) idx_z < (duk_uint_t) duk_get_top(ctx));

        /*
         *  Fast paths
         */

#if defined(DUK_USE_FASTINT)
        if (DUK_TVAL_IS_FASTINT(tv_x) && DUK_TVAL_IS_FASTINT(tv_y)) {
                duk_int64_t v1, v2, v3;
                duk_int32_t v3_hi;
                duk_tval *tv_z;

                /* Input values are signed 48-bit so we can detect overflow
                 * reliably from high bits or just a comparison.
                 */

                v1 = DUK_TVAL_GET_FASTINT(tv_x);
                v2 = DUK_TVAL_GET_FASTINT(tv_y);
                v3 = v1 + v2;
                v3_hi = (duk_int32_t) (v3 >> 32);
                if (DUK_LIKELY(v3_hi >= -0x8000LL && v3_hi <= 0x7fffLL)) {
                        tv_z = thr->valstack_bottom + idx_z;
                        DUK_TVAL_SET_FASTINT_UPDREF(thr, tv_z, v3);  /* side effects */
                        return;
                } else {
                        /* overflow, fall through */
                        ;
                }
        }
#endif  /* DUK_USE_FASTINT */

        if (DUK_TVAL_IS_NUMBER(tv_x) && DUK_TVAL_IS_NUMBER(tv_y)) {
                duk_tval *tv_z;

                du.d = DUK_TVAL_GET_NUMBER(tv_x) + DUK_TVAL_GET_NUMBER(tv_y);
                DUK_DBLUNION_NORMALIZE_NAN_CHECK(&du);
                DUK_ASSERT(DUK_DBLUNION_IS_NORMALIZED(&du));

                tv_z = thr->valstack_bottom + idx_z;
                DUK_TVAL_SET_NUMBER_UPDREF(thr, tv_z, du.d);  /* side effects */
                return;
        }

        /*
         *  Slow path: potentially requires function calls for coercion
         */

        duk_push_tval(ctx, tv_x);
        duk_push_tval(ctx, tv_y);
        duk_to_primitive(ctx, -2, DUK_HINT_NONE);  /* side effects -> don't use tv_x, tv_y after */
        duk_to_primitive(ctx, -1, DUK_HINT_NONE);

        /* As a first approximation, buffer values are coerced to strings
         * for addition.  This means that adding two buffers currently
         * results in a string.
         */
        if (duk_check_type_mask(ctx, -2, DUK_TYPE_MASK_STRING | DUK_TYPE_MASK_BUFFER) ||
            duk_check_type_mask(ctx, -1, DUK_TYPE_MASK_STRING | DUK_TYPE_MASK_BUFFER)) {
                duk_to_string(ctx, -2);
                duk_to_string(ctx, -1);
                duk_concat(ctx, 2);  /* [... s1 s2] -> [... s1+s2] */
                duk_replace(ctx, (duk_idx_t) idx_z);  /* side effects */
        } else {
                duk_double_t d1, d2;

                d1 = duk_to_number(ctx, -2);
                d2 = duk_to_number(ctx, -1);
                DUK_ASSERT(duk_is_number(ctx, -2));
                DUK_ASSERT(duk_is_number(ctx, -1));
                DUK_ASSERT_DOUBLE_IS_NORMALIZED(d1);
                DUK_ASSERT_DOUBLE_IS_NORMALIZED(d2);

                du.d = d1 + d2;
                DUK_DBLUNION_NORMALIZE_NAN_CHECK(&du);
                DUK_ASSERT(DUK_DBLUNION_IS_NORMALIZED(&du));

                duk_pop_2(ctx);
                duk_push_number(ctx, du.d);
                duk_replace(ctx, (duk_idx_t) idx_z);  /* side effects */
        }
}

DUK_LOCAL void duk__vm_arith_binary_op(duk_hthread *thr, duk_tval *tv_x, duk_tval *tv_y, duk_idx_t idx_z, duk_small_uint_fast_t opcode) {
        /*
         *  Arithmetic operations other than '+' have number-only semantics
         *  and are implemented here.  The separate switch-case here means a
         *  "double dispatch" of the arithmetic opcode, but saves code space.
         *
         *  E5 Sections 11.5, 11.5.1, 11.5.2, 11.5.3, 11.6, 11.6.1, 11.6.2, 11.6.3.
         */

        duk_context *ctx = (duk_context *) thr;
        duk_tval *tv_z;
        duk_double_t d1, d2;
        duk_double_union du;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(ctx != NULL);
        DUK_ASSERT(tv_x != NULL);  /* may be reg or const */
        DUK_ASSERT(tv_y != NULL);  /* may be reg or const */
        DUK_ASSERT_DISABLE(idx_z >= 0);  /* unsigned */
        DUK_ASSERT((duk_uint_t) idx_z < (duk_uint_t) duk_get_top(ctx));

#if defined(DUK_USE_FASTINT)
        if (DUK_TVAL_IS_FASTINT(tv_x) && DUK_TVAL_IS_FASTINT(tv_y)) {
                duk_int64_t v1, v2, v3;
                duk_int32_t v3_hi;

                v1 = DUK_TVAL_GET_FASTINT(tv_x);
                v2 = DUK_TVAL_GET_FASTINT(tv_y);

                switch (opcode) {
                case DUK_OP_SUB: {
                        v3 = v1 - v2;
                        break;
                }
                case DUK_OP_MUL: {
                        /* Must ensure result is 64-bit (no overflow); a
                         * simple and sufficient fast path is to allow only
                         * 32-bit inputs.  Avoid zero inputs to avoid
                         * negative zero issues (-1 * 0 = -0, for instance).
                         */
                        if (v1 >= -0x80000000LL && v1 <= 0x7fffffffLL && v1 != 0 &&
                            v2 >= -0x80000000LL && v2 <= 0x7fffffffLL && v2 != 0) {
                                v3 = v1 * v2;
                        } else {
                                goto skip_fastint;
                        }
                        break;
                }
                case DUK_OP_DIV: {
                        /* Don't allow a zero divisor.  Fast path check by
                         * "verifying" with multiplication.  Also avoid zero
                         * dividend to avoid negative zero issues (0 / -1 = -0
                         * for instance).
                         */
                        if (v1 == 0 || v2 == 0) {
                                goto skip_fastint;
                        }
                        v3 = v1 / v2;
                        if (v3 * v2 != v1) {
                                goto skip_fastint;
                        }
                        break;
                }
                case DUK_OP_MOD: {
                        /* Don't allow a zero divisor.  Restrict both v1 and
                         * v2 to positive values to avoid compiler specific
                         * behavior.
                         */
                        if (v1 < 1 || v2 < 1) {
                                goto skip_fastint;
                        }
                        v3 = v1 % v2;
                        DUK_ASSERT(v3 >= 0);
                        DUK_ASSERT(v3 < v2);
                        DUK_ASSERT(v1 - (v1 / v2) * v2 == v3);
                        break;
                }
                default: {
                        DUK_UNREACHABLE();
                        goto skip_fastint;
                }
                }

                v3_hi = (duk_int32_t) (v3 >> 32);
                if (DUK_LIKELY(v3_hi >= -0x8000LL && v3_hi <= 0x7fffLL)) {
                        tv_z = thr->valstack_bottom + idx_z;
                        DUK_TVAL_SET_FASTINT_UPDREF(thr, tv_z, v3);  /* side effects */
                        return;
                }
                /* fall through if overflow etc */
        }
 skip_fastint:
#endif  /* DUK_USE_FASTINT */

        if (DUK_TVAL_IS_NUMBER(tv_x) && DUK_TVAL_IS_NUMBER(tv_y)) {
                /* fast path */
                d1 = DUK_TVAL_GET_NUMBER(tv_x);
                d2 = DUK_TVAL_GET_NUMBER(tv_y);
        } else {
                duk_push_tval(ctx, tv_x);
                duk_push_tval(ctx, tv_y);
                d1 = duk_to_number(ctx, -2);  /* side effects */
                d2 = duk_to_number(ctx, -1);
                DUK_ASSERT(duk_is_number(ctx, -2));
                DUK_ASSERT(duk_is_number(ctx, -1));
                DUK_ASSERT_DOUBLE_IS_NORMALIZED(d1);
                DUK_ASSERT_DOUBLE_IS_NORMALIZED(d2);
                duk_pop_2(ctx);
        }

        switch (opcode) {
        case DUK_OP_SUB: {
                du.d = d1 - d2;
                break;
        }
        case DUK_OP_MUL: {
                du.d = d1 * d2;
                break;
        }
        case DUK_OP_DIV: {
                du.d = d1 / d2;
                break;
        }
        case DUK_OP_MOD: {
                du.d = duk__compute_mod(d1, d2);
                break;
        }
        default: {
                DUK_UNREACHABLE();
                du.d = DUK_DOUBLE_NAN;  /* should not happen */
                break;
        }
        }

        /* important to use normalized NaN with 8-byte tagged types */
        DUK_DBLUNION_NORMALIZE_NAN_CHECK(&du);
        DUK_ASSERT(DUK_DBLUNION_IS_NORMALIZED(&du));

        tv_z = thr->valstack_bottom + idx_z;
        DUK_TVAL_SET_NUMBER_UPDREF(thr, tv_z, du.d);  /* side effects */
}

DUK_LOCAL void duk__vm_bitwise_binary_op(duk_hthread *thr, duk_tval *tv_x, duk_tval *tv_y, duk_small_uint_fast_t idx_z, duk_small_uint_fast_t opcode) {
        /*
         *  Binary bitwise operations use different coercions (ToInt32, ToUint32)
         *  depending on the operation.  We coerce the arguments first using
         *  ToInt32(), and then cast to an 32-bit value if necessary.  Note that
         *  such casts must be correct even if there is no native 32-bit type
         *  (e.g., duk_int32_t and duk_uint32_t are 64-bit).
         *
         *  E5 Sections 11.10, 11.7.1, 11.7.2, 11.7.3
         */

        duk_context *ctx = (duk_context *) thr;
        duk_tval *tv_z;
        duk_int32_t i1, i2, i3;
        duk_uint32_t u1, u2, u3;
#if defined(DUK_USE_FASTINT)
        duk_int64_t fi3;
#else
        duk_double_t d3;
#endif

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(ctx != NULL);
        DUK_ASSERT(tv_x != NULL);  /* may be reg or const */
        DUK_ASSERT(tv_y != NULL);  /* may be reg or const */
        DUK_ASSERT_DISABLE(idx_z >= 0);  /* unsigned */
        DUK_ASSERT((duk_uint_t) idx_z < (duk_uint_t) duk_get_top(ctx));

#if defined(DUK_USE_FASTINT)
        if (DUK_TVAL_IS_FASTINT(tv_x) && DUK_TVAL_IS_FASTINT(tv_y)) {
                i1 = (duk_int32_t) DUK_TVAL_GET_FASTINT_I32(tv_x);
                i2 = (duk_int32_t) DUK_TVAL_GET_FASTINT_I32(tv_y);
        }
        else
#endif  /* DUK_USE_FASTINT */
        {
                duk_push_tval(ctx, tv_x);
                duk_push_tval(ctx, tv_y);
                i1 = duk_to_int32(ctx, -2);
                i2 = duk_to_int32(ctx, -1);
                duk_pop_2(ctx);
        }

        switch (opcode) {
        case DUK_OP_BAND: {
                i3 = i1 & i2;
                break;
        }
        case DUK_OP_BOR: {
                i3 = i1 | i2;
                break;
        }
        case DUK_OP_BXOR: {
                i3 = i1 ^ i2;
                break;
        }
        case DUK_OP_BASL: {
                /* Signed shift, named "arithmetic" (asl) because the result
                 * is signed, e.g. 4294967295 << 1 -> -2.  Note that result
                 * must be masked.
                 */

                u2 = ((duk_uint32_t) i2) & 0xffffffffUL;
                i3 = i1 << (u2 & 0x1f);                      /* E5 Section 11.7.1, steps 7 and 8 */
                i3 = i3 & ((duk_int32_t) 0xffffffffUL);      /* Note: left shift, should mask */
                break;
        }
        case DUK_OP_BASR: {
                /* signed shift */

                u2 = ((duk_uint32_t) i2) & 0xffffffffUL;
                i3 = i1 >> (u2 & 0x1f);                      /* E5 Section 11.7.2, steps 7 and 8 */
                break;
        }
        case DUK_OP_BLSR: {
                /* unsigned shift */

                u1 = ((duk_uint32_t) i1) & 0xffffffffUL;
                u2 = ((duk_uint32_t) i2) & 0xffffffffUL;

                /* special result value handling */
                u3 = u1 >> (u2 & 0x1f);     /* E5 Section 11.7.2, steps 7 and 8 */
#if defined(DUK_USE_FASTINT)
                fi3 = (duk_int64_t) u3;
                goto fastint_result_set;
#else
                d3 = (duk_double_t) u3;
                goto result_set;
#endif
        }
        default: {
                DUK_UNREACHABLE();
                i3 = 0;  /* should not happen */
                break;
        }
        }

#if defined(DUK_USE_FASTINT)
        /* Result is always fastint compatible. */
        /* XXX: Set 32-bit result (but must then handle signed and
         * unsigned results separately).
         */
        fi3 = (duk_int64_t) i3;

 fastint_result_set:
        tv_z = thr->valstack_bottom + idx_z;
        DUK_TVAL_SET_FASTINT_UPDREF(thr, tv_z, fi3);  /* side effects */
#else
        d3 = (duk_double_t) i3;

 result_set:
        DUK_ASSERT(!DUK_ISNAN(d3));            /* 'd3' is never NaN, so no need to normalize */
        DUK_ASSERT_DOUBLE_IS_NORMALIZED(d3);   /* always normalized */

        tv_z = thr->valstack_bottom + idx_z;
        DUK_TVAL_SET_NUMBER_UPDREF(thr, tv_z, d3);  /* side effects */
#endif
}

/* In-place unary operation. */
DUK_LOCAL void duk__vm_arith_unary_op(duk_hthread *thr, duk_tval *tv_x, duk_idx_t idx_x, duk_small_uint_fast_t opcode) {
        /*
         *  Arithmetic operations other than '+' have number-only semantics
         *  and are implemented here.  The separate switch-case here means a
         *  "double dispatch" of the arithmetic opcode, but saves code space.
         *
         *  E5 Sections 11.5, 11.5.1, 11.5.2, 11.5.3, 11.6, 11.6.1, 11.6.2, 11.6.3.
         */

        duk_context *ctx = (duk_context *) thr;
        duk_double_t d1;
        duk_double_union du;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(ctx != NULL);
        DUK_ASSERT(opcode == DUK_EXTRAOP_UNM || opcode == DUK_EXTRAOP_UNP);
        DUK_ASSERT(tv_x != NULL);
        DUK_ASSERT(idx_x >= 0);

#if defined(DUK_USE_FASTINT)
        if (DUK_TVAL_IS_FASTINT(tv_x)) {
                duk_int64_t v1, v2;

                v1 = DUK_TVAL_GET_FASTINT(tv_x);
                if (opcode == DUK_EXTRAOP_UNM) {
                        /* The smallest fastint is no longer 48-bit when
                         * negated.  Positive zero becames negative zero
                         * (cannot be represented) when negated.
                         */
                        if (DUK_LIKELY(v1 != DUK_FASTINT_MIN && v1 != 0)) {
                                v2 = -v1;
                                DUK_TVAL_SET_FASTINT(tv_x, v2);  /* no refcount changes */
                                return;
                        }
                } else {
                        /* ToNumber() for a fastint is a no-op. */
                        DUK_ASSERT(opcode == DUK_EXTRAOP_UNP);
                        return;
                }
                /* fall through if overflow etc */
        }
#endif  /* DUK_USE_FASTINT */

        if (!DUK_TVAL_IS_NUMBER(tv_x)) {
                duk_to_number(ctx, idx_x);  /* side effects, perform in-place */
                tv_x = DUK_GET_TVAL_POSIDX(ctx, idx_x);
                DUK_ASSERT(tv_x != NULL);
                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_x));
        }

        d1 = DUK_TVAL_GET_NUMBER(tv_x);
        if (opcode == DUK_EXTRAOP_UNM) {
                du.d = -d1;
        } else {
                /* ToNumber() for a double is a no-op. */
                DUK_ASSERT(opcode == DUK_EXTRAOP_UNP);
                du.d = d1;
        }
        DUK_DBLUNION_NORMALIZE_NAN_CHECK(&du);  /* mandatory if du.d is a NaN */

        DUK_ASSERT(DUK_DBLUNION_IS_NORMALIZED(&du));

#if defined(DUK_USE_FASTINT)
        /* Unary plus is used to force a fastint check, so must include
         * downgrade check.
         */
        DUK_TVAL_SET_NUMBER_CHKFAST(tv_x, du.d);  /* no refcount changes */
#else
        DUK_TVAL_SET_NUMBER(tv_x, du.d);  /* no refcount changes */
#endif
}

DUK_LOCAL void duk__vm_bitwise_not(duk_hthread *thr, duk_tval *tv_x, duk_uint_fast_t idx_z) {
        /*
         *  E5 Section 11.4.8
         */

        duk_context *ctx = (duk_context *) thr;
        duk_tval *tv_z;
        duk_int32_t i1, i2;
#if !defined(DUK_USE_FASTINT)
        duk_double_t d2;
#endif

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(ctx != NULL);
        DUK_ASSERT(tv_x != NULL);  /* may be reg or const */
        DUK_ASSERT_DISABLE(idx_z >= 0);
        DUK_ASSERT((duk_uint_t) idx_z < (duk_uint_t) duk_get_top(ctx));

#if defined(DUK_USE_FASTINT)
        if (DUK_TVAL_IS_FASTINT(tv_x)) {
                i1 = (duk_int32_t) DUK_TVAL_GET_FASTINT_I32(tv_x);
        }
        else
#endif  /* DUK_USE_FASTINT */
        {
                duk_push_tval(ctx, tv_x);
                i1 = duk_to_int32(ctx, -1);
                duk_pop(ctx);
        }

        i2 = ~i1;

#if defined(DUK_USE_FASTINT)
        /* Result is always fastint compatible. */
        tv_z = thr->valstack_bottom + idx_z;
        DUK_TVAL_SET_FASTINT_I32_UPDREF(thr, tv_z, i2);  /* side effects */
#else
        d2 = (duk_double_t) i2;

        DUK_ASSERT(!DUK_ISNAN(d2));            /* 'val' is never NaN, so no need to normalize */
        DUK_ASSERT_DOUBLE_IS_NORMALIZED(d2);   /* always normalized */

        tv_z = thr->valstack_bottom + idx_z;
        DUK_TVAL_SET_NUMBER_UPDREF(thr, tv_z, d2);  /* side effects */
#endif
}

DUK_LOCAL void duk__vm_logical_not(duk_hthread *thr, duk_tval *tv_x, duk_tval *tv_z) {
        /*
         *  E5 Section 11.4.9
         */

        duk_bool_t res;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(tv_x != NULL);  /* may be reg or const */
        DUK_ASSERT(tv_z != NULL);  /* reg */

        DUK_UNREF(thr);  /* w/o refcounts */

        /* ToBoolean() does not require any operations with side effects so
         * we can do it efficiently.  For footprint it would be better to use
         * duk_js_toboolean() and then push+replace to the result slot.
         */
        res = duk_js_toboolean(tv_x);  /* does not modify tv_x */
        DUK_ASSERT(res == 0 || res == 1);
        res ^= 1;
        DUK_TVAL_SET_BOOLEAN_UPDREF(thr, tv_z, res);  /* side effects */
}

/*
 *  Longjmp and other control flow transfer for the bytecode executor.
 *
 *  The longjmp handler can handle all longjmp types: error, yield, and
 *  resume (pseudotypes are never actually thrown).
 *
 *  Error policy for longjmp: should not ordinarily throw errors; if errors
 *  occur (e.g. due to out-of-memory) they bubble outwards rather than being
 *  handled recursively.
 */

#define DUK__LONGJMP_RESTART   0  /* state updated, restart bytecode execution */
#define DUK__LONGJMP_RETHROW   1  /* exit bytecode executor by rethrowing an error to caller */

#define DUK__RETHAND_RESTART   0  /* state updated, restart bytecode execution */
#define DUK__RETHAND_FINISHED  1  /* exit bytecode execution with return value */

/* XXX: optimize reconfig valstack operations so that resize, clamp, and setting
 * top are combined into one pass.
 */

/* Reconfigure value stack for return to an Ecmascript function at 'act_idx'. */
DUK_LOCAL void duk__reconfig_valstack_ecma_return(duk_hthread *thr, duk_size_t act_idx) {
        duk_activation *act;
        duk_hcompiledfunction *h_func;
        duk_idx_t clamp_top;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT_DISABLE(act_idx >= 0);  /* unsigned */
        DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + act_idx) != NULL);
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + act_idx)));
        DUK_ASSERT_DISABLE(thr->callstack[act_idx].idx_retval >= 0);  /* unsigned */

        /* Clamp so that values at 'clamp_top' and above are wiped and won't
         * retain reachable garbage.  Then extend to 'nregs' because we're
         * returning to an Ecmascript function.
         */

        act = thr->callstack + act_idx;
        h_func = (duk_hcompiledfunction *) DUK_ACT_GET_FUNC(act);

        thr->valstack_bottom = thr->valstack + act->idx_bottom;
        DUK_ASSERT(act->idx_retval >= act->idx_bottom);
        clamp_top = (duk_idx_t) (act->idx_retval - act->idx_bottom + 1);  /* +1 = one retval */
        duk_set_top((duk_context *) thr, clamp_top);
        act = NULL;

        (void) duk_valstack_resize_raw((duk_context *) thr,
                                       (thr->valstack_bottom - thr->valstack) +  /* bottom of current func */
                                           h_func->nregs +                       /* reg count */
                                           DUK_VALSTACK_INTERNAL_EXTRA,          /* + spare */
                                       DUK_VSRESIZE_FLAG_SHRINK |                /* flags */
                                       0 /* no compact */ |
                                       DUK_VSRESIZE_FLAG_THROW);

        duk_set_top((duk_context *) thr, h_func->nregs);
}

DUK_LOCAL void duk__reconfig_valstack_ecma_catcher(duk_hthread *thr, duk_size_t act_idx, duk_size_t cat_idx) {
        duk_activation *act;
        duk_catcher *cat;
        duk_hcompiledfunction *h_func;
        duk_idx_t clamp_top;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT_DISABLE(act_idx >= 0);  /* unsigned */
        DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + act_idx) != NULL);
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + act_idx)));
        DUK_ASSERT_DISABLE(thr->callstack[act_idx].idx_retval >= 0);  /* unsigned */

        act = thr->callstack + act_idx;
        cat = thr->catchstack + cat_idx;
        h_func = (duk_hcompiledfunction *) DUK_ACT_GET_FUNC(act);

        thr->valstack_bottom = thr->valstack + act->idx_bottom;
        DUK_ASSERT(cat->idx_base >= act->idx_bottom);
        clamp_top = (duk_idx_t) (cat->idx_base - act->idx_bottom + 2);  /* +2 = catcher value, catcher lj_type */
        duk_set_top((duk_context *) thr, clamp_top);
        act = NULL;
        cat = NULL;

        (void) duk_valstack_resize_raw((duk_context *) thr,
                                       (thr->valstack_bottom - thr->valstack) +  /* bottom of current func */
                                           h_func->nregs +                       /* reg count */
                                           DUK_VALSTACK_INTERNAL_EXTRA,          /* + spare */
                                       DUK_VSRESIZE_FLAG_SHRINK |                /* flags */
                                       0 /* no compact */ |
                                       DUK_VSRESIZE_FLAG_THROW);

        duk_set_top((duk_context *) thr, h_func->nregs);
}

/* Set catcher regs: idx_base+0 = value, idx_base+1 = lj_type. */
DUK_LOCAL void duk__set_catcher_regs(duk_hthread *thr, duk_size_t cat_idx, duk_tval *tv_val_unstable, duk_small_uint_t lj_type) {
        duk_tval *tv1;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(tv_val_unstable != NULL);

        tv1 = thr->valstack + thr->catchstack[cat_idx].idx_base;
        DUK_ASSERT(tv1 < thr->valstack_top);
        DUK_TVAL_SET_TVAL_UPDREF(thr, tv1, tv_val_unstable);  /* side effects */

        tv1 = thr->valstack + thr->catchstack[cat_idx].idx_base + 1;
        DUK_ASSERT(tv1 < thr->valstack_top);

        DUK_TVAL_SET_FASTINT_U32_UPDREF(thr, tv1, (duk_uint32_t) lj_type);  /* side effects */
}

DUK_LOCAL void duk__handle_catch(duk_hthread *thr, duk_size_t cat_idx, duk_tval *tv_val_unstable, duk_small_uint_t lj_type) {
        duk_context *ctx;
        duk_activation *act;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(tv_val_unstable != NULL);
        ctx = (duk_context *) thr;

        duk__set_catcher_regs(thr, cat_idx, tv_val_unstable, lj_type);

        duk_hthread_catchstack_unwind(thr, cat_idx + 1);
        duk_hthread_callstack_unwind(thr, thr->catchstack[cat_idx].callstack_index + 1);

        DUK_ASSERT(thr->callstack_top >= 1);
        DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1) != NULL);
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1)));

        duk__reconfig_valstack_ecma_catcher(thr, thr->callstack_top - 1, cat_idx);

        DUK_ASSERT(thr->callstack_top >= 1);
        act = thr->callstack + thr->callstack_top - 1;
        act->curr_pc = thr->catchstack[cat_idx].pc_base + 0;  /* +0 = catch */
        act = NULL;

        /*
         *  If entering a 'catch' block which requires an automatic
         *  catch variable binding, create the lexical environment.
         *
         *  The binding is mutable (= writable) but not deletable.
         *  Step 4 for the catch production in E5 Section 12.14;
         *  no value is given for CreateMutableBinding 'D' argument,
         *  which implies the binding is not deletable.
         */

        if (DUK_CAT_HAS_CATCH_BINDING_ENABLED(&thr->catchstack[cat_idx])) {
                duk_hobject *new_env;
                duk_hobject *act_lex_env;

                DUK_DDD(DUK_DDDPRINT("catcher has an automatic catch binding"));

                /* Note: 'act' is dangerous here because it may get invalidate at many
                 * points, so we re-lookup it multiple times.
                 */
                DUK_ASSERT(thr->callstack_top >= 1);
                act = thr->callstack + thr->callstack_top - 1;

                if (act->lex_env == NULL) {
                        DUK_ASSERT(act->var_env == NULL);
                        DUK_DDD(DUK_DDDPRINT("delayed environment initialization"));

                        /* this may have side effects, so re-lookup act */
                        duk_js_init_activation_environment_records_delayed(thr, act);
                        act = thr->callstack + thr->callstack_top - 1;
                }
                DUK_ASSERT(act->lex_env != NULL);
                DUK_ASSERT(act->var_env != NULL);
                DUK_ASSERT(DUK_ACT_GET_FUNC(act) != NULL);
                DUK_UNREF(act);  /* unreferenced without assertions */

                act = thr->callstack + thr->callstack_top - 1;
                act_lex_env = act->lex_env;
                act = NULL;  /* invalidated */

                (void) duk_push_object_helper_proto(ctx,
                                                    DUK_HOBJECT_FLAG_EXTENSIBLE |
                                                    DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_DECENV),
                                                    act_lex_env);
                new_env = DUK_GET_HOBJECT_NEGIDX(ctx, -1);
                DUK_ASSERT(new_env != NULL);
                DUK_DDD(DUK_DDDPRINT("new_env allocated: %!iO", (duk_heaphdr *) new_env));

                /* Note: currently the catch binding is handled without a register
                 * binding because we don't support dynamic register bindings (they
                 * must be fixed for an entire function).  So, there is no need to
                 * record regbases etc.
                 */

                DUK_ASSERT(thr->catchstack[cat_idx].h_varname != NULL);
                duk_push_hstring(ctx, thr->catchstack[cat_idx].h_varname);
                duk_push_tval(ctx, thr->valstack + thr->catchstack[cat_idx].idx_base);
                duk_xdef_prop(ctx, -3, DUK_PROPDESC_FLAGS_W);  /* writable, not configurable */

                act = thr->callstack + thr->callstack_top - 1;
                act->lex_env = new_env;
                DUK_HOBJECT_INCREF(thr, new_env);  /* reachable through activation */

                DUK_CAT_SET_LEXENV_ACTIVE(&thr->catchstack[cat_idx]);

                duk_pop(ctx);

                DUK_DDD(DUK_DDDPRINT("new_env finished: %!iO", (duk_heaphdr *) new_env));
        }

        DUK_CAT_CLEAR_CATCH_ENABLED(&thr->catchstack[cat_idx]);
}

DUK_LOCAL void duk__handle_finally(duk_hthread *thr, duk_size_t cat_idx, duk_tval *tv_val_unstable, duk_small_uint_t lj_type) {
        duk_activation *act;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(tv_val_unstable != NULL);

        duk__set_catcher_regs(thr, cat_idx, tv_val_unstable, lj_type);

        duk_hthread_catchstack_unwind(thr, cat_idx + 1);  /* cat_idx catcher is kept, even for finally */
        duk_hthread_callstack_unwind(thr, thr->catchstack[cat_idx].callstack_index + 1);

        DUK_ASSERT(thr->callstack_top >= 1);
        DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1) != NULL);
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1)));

        duk__reconfig_valstack_ecma_catcher(thr, thr->callstack_top - 1, cat_idx);

        DUK_ASSERT(thr->callstack_top >= 1);
        act = thr->callstack + thr->callstack_top - 1;
        act->curr_pc = thr->catchstack[cat_idx].pc_base + 1;  /* +1 = finally */
        act = NULL;

        DUK_CAT_CLEAR_FINALLY_ENABLED(&thr->catchstack[cat_idx]);
}

DUK_LOCAL void duk__handle_label(duk_hthread *thr, duk_size_t cat_idx, duk_small_uint_t lj_type) {
        duk_activation *act;

        DUK_ASSERT(thr != NULL);

        DUK_ASSERT(thr->callstack_top >= 1);
        act = thr->callstack + thr->callstack_top - 1;

        DUK_ASSERT(DUK_ACT_GET_FUNC(act) != NULL);
        DUK_ASSERT(DUK_HOBJECT_HAS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(act)));

        /* +0 = break, +1 = continue */
        act->curr_pc = thr->catchstack[cat_idx].pc_base + (lj_type == DUK_LJ_TYPE_CONTINUE ? 1 : 0);
        act = NULL;  /* invalidated */

        duk_hthread_catchstack_unwind(thr, cat_idx + 1);  /* keep label catcher */
        /* no need to unwind callstack */

        /* valstack should not need changes */
#if defined(DUK_USE_ASSERTIONS)
        DUK_ASSERT(thr->callstack_top >= 1);
        act = thr->callstack + thr->callstack_top - 1;
        DUK_ASSERT((duk_size_t) (thr->valstack_top - thr->valstack_bottom) ==
                   (duk_size_t) ((duk_hcompiledfunction *) DUK_ACT_GET_FUNC(act))->nregs);
#endif
}

/* Called for handling both a longjmp() with type DUK_LJ_TYPE_YIELD and
 * when a RETURN opcode terminates a thread and yields to the resumer.
 */
DUK_LOCAL void duk__handle_yield(duk_hthread *thr, duk_hthread *resumer, duk_size_t act_idx, duk_tval *tv_val_unstable) {
        duk_tval *tv1;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(resumer != NULL);
        DUK_ASSERT(tv_val_unstable != NULL);
        DUK_ASSERT(DUK_ACT_GET_FUNC(resumer->callstack + act_idx) != NULL);
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(resumer->callstack + act_idx)));  /* resume caller must be an ecmascript func */

        tv1 = resumer->valstack + resumer->callstack[act_idx].idx_retval;  /* return value from Duktape.Thread.resume() */
        DUK_TVAL_SET_TVAL_UPDREF(thr, tv1, tv_val_unstable);  /* side effects */

        duk_hthread_callstack_unwind(resumer, act_idx + 1);  /* unwind to 'resume' caller */

        /* no need to unwind catchstack */
        duk__reconfig_valstack_ecma_return(resumer, act_idx);

        /* caller must change active thread, and set thr->resumer to NULL */
}

DUK_LOCAL
duk_small_uint_t duk__handle_longjmp(duk_hthread *thr,
                                     duk_hthread *entry_thread,
                                     duk_size_t entry_callstack_top) {
        duk_size_t entry_callstack_index;
        duk_small_uint_t retval = DUK__LONGJMP_RESTART;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(entry_thread != NULL);
        DUK_ASSERT(entry_callstack_top > 0);  /* guarantees entry_callstack_top - 1 >= 0 */

        entry_callstack_index = entry_callstack_top - 1;

        /* 'thr' is the current thread, as no-one resumes except us and we
         * switch 'thr' in that case.
         */
        DUK_ASSERT(thr == thr->heap->curr_thread);

        /*
         *  (Re)try handling the longjmp.
         *
         *  A longjmp handler may convert the longjmp to a different type and
         *  "virtually" rethrow by goto'ing to 'check_longjmp'.  Before the goto,
         *  the following must be updated:
         *    - the heap 'lj' state
         *    - 'thr' must reflect the "throwing" thread
         */

 check_longjmp:

        DUK_DD(DUK_DDPRINT("handling longjmp: type=%ld, value1=%!T, value2=%!T, iserror=%ld",
                           (long) thr->heap->lj.type,
                           (duk_tval *) &thr->heap->lj.value1,
                           (duk_tval *) &thr->heap->lj.value2,
                           (long) thr->heap->lj.iserror));

        switch (thr->heap->lj.type) {

        case DUK_LJ_TYPE_RESUME: {
                /*
                 *  Note: lj.value1 is 'value', lj.value2 is 'resumee'.
                 *  This differs from YIELD.
                 */

                duk_tval *tv;
                duk_tval *tv2;
                duk_size_t act_idx;
                duk_hthread *resumee;

                /* duk_bi_duk_object_yield() and duk_bi_duk_object_resume() ensure all of these are met */

                DUK_ASSERT(thr->state == DUK_HTHREAD_STATE_RUNNING);                                                         /* unchanged by Duktape.Thread.resume() */
                DUK_ASSERT(thr->callstack_top >= 2);                                                                         /* Ecmascript activation + Duktape.Thread.resume() activation */
                DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1) != NULL &&
                           DUK_HOBJECT_IS_NATIVEFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1)) &&
                           ((duk_hnativefunction *) DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1))->func == duk_bi_thread_resume);
                DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 2) != NULL &&
                           DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 2)));      /* an Ecmascript function */
                DUK_ASSERT_DISABLE((thr->callstack + thr->callstack_top - 2)->idx_retval >= 0);                              /* unsigned */

                tv = &thr->heap->lj.value2;  /* resumee */
                DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv));
                DUK_ASSERT(DUK_TVAL_GET_OBJECT(tv) != NULL);
                DUK_ASSERT(DUK_HOBJECT_IS_THREAD(DUK_TVAL_GET_OBJECT(tv)));
                resumee = (duk_hthread *) DUK_TVAL_GET_OBJECT(tv);

                DUK_ASSERT(resumee != NULL);
                DUK_ASSERT(resumee->resumer == NULL);
                DUK_ASSERT(resumee->state == DUK_HTHREAD_STATE_INACTIVE ||
                           resumee->state == DUK_HTHREAD_STATE_YIELDED);                                                     /* checked by Duktape.Thread.resume() */
                DUK_ASSERT(resumee->state != DUK_HTHREAD_STATE_YIELDED ||
                           resumee->callstack_top >= 2);                                                                     /* YIELDED: Ecmascript activation + Duktape.Thread.yield() activation */
                DUK_ASSERT(resumee->state != DUK_HTHREAD_STATE_YIELDED ||
                           (DUK_ACT_GET_FUNC(resumee->callstack + resumee->callstack_top - 1) != NULL &&
                            DUK_HOBJECT_IS_NATIVEFUNCTION(DUK_ACT_GET_FUNC(resumee->callstack + resumee->callstack_top - 1)) &&
                            ((duk_hnativefunction *) DUK_ACT_GET_FUNC(resumee->callstack + resumee->callstack_top - 1))->func == duk_bi_thread_yield));
                DUK_ASSERT(resumee->state != DUK_HTHREAD_STATE_YIELDED ||
                           (DUK_ACT_GET_FUNC(resumee->callstack + resumee->callstack_top - 2) != NULL &&
                            DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(resumee->callstack + resumee->callstack_top - 2))));      /* an Ecmascript function */
                DUK_ASSERT_DISABLE(resumee->state != DUK_HTHREAD_STATE_YIELDED ||
                           (resumee->callstack + resumee->callstack_top - 2)->idx_retval >= 0);                              /* idx_retval unsigned */
                DUK_ASSERT(resumee->state != DUK_HTHREAD_STATE_INACTIVE ||
                           resumee->callstack_top == 0);                                                                     /* INACTIVE: no activation, single function value on valstack */
                DUK_ASSERT(resumee->state != DUK_HTHREAD_STATE_INACTIVE ||
                           (resumee->valstack_top == resumee->valstack + 1 &&
                            DUK_TVAL_IS_OBJECT(resumee->valstack_top - 1) &&
                            DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_TVAL_GET_OBJECT(resumee->valstack_top - 1))));

                if (thr->heap->lj.iserror) {
                        /*
                         *  Throw the error in the resumed thread's context; the
                         *  error value is pushed onto the resumee valstack.
                         *
                         *  Note: the callstack of the target may empty in this case
                         *  too (i.e. the target thread has never been resumed).  The
                         *  value stack will contain the initial function in that case,
                         *  which we simply ignore.
                         */

                        resumee->resumer = thr;
                        resumee->state = DUK_HTHREAD_STATE_RUNNING;
                        thr->state = DUK_HTHREAD_STATE_RESUMED;
                        DUK_HEAP_SWITCH_THREAD(thr->heap, resumee);
                        thr = resumee;

                        thr->heap->lj.type = DUK_LJ_TYPE_THROW;

                        /* thr->heap->lj.value1 is already the value to throw */
                        /* thr->heap->lj.value2 is 'thread', will be wiped out at the end */

                        DUK_ASSERT(thr->heap->lj.iserror);  /* already set */

                        DUK_DD(DUK_DDPRINT("-> resume with an error, converted to a throw in the resumee, propagate"));
                        goto check_longjmp;
                } else if (resumee->state == DUK_HTHREAD_STATE_YIELDED) {
                        act_idx = resumee->callstack_top - 2;  /* Ecmascript function */
                        DUK_ASSERT_DISABLE(resumee->callstack[act_idx].idx_retval >= 0);  /* unsigned */

                        tv = resumee->valstack + resumee->callstack[act_idx].idx_retval;  /* return value from Duktape.Thread.yield() */
                        DUK_ASSERT(tv >= resumee->valstack && tv < resumee->valstack_top);
                        tv2 = &thr->heap->lj.value1;
                        DUK_TVAL_SET_TVAL_UPDREF(thr, tv, tv2);  /* side effects */

                        duk_hthread_callstack_unwind(resumee, act_idx + 1);  /* unwind to 'yield' caller */

                        /* no need to unwind catchstack */

                        duk__reconfig_valstack_ecma_return(resumee, act_idx);

                        resumee->resumer = thr;
                        resumee->state = DUK_HTHREAD_STATE_RUNNING;
                        thr->state = DUK_HTHREAD_STATE_RESUMED;
                        DUK_HEAP_SWITCH_THREAD(thr->heap, resumee);
#if 0
                        thr = resumee;  /* not needed, as we exit right away */
#endif
                        DUK_DD(DUK_DDPRINT("-> resume with a value, restart execution in resumee"));
                        retval = DUK__LONGJMP_RESTART;
                        goto wipe_and_return;
                } else {
                        duk_small_uint_t call_flags;
                        duk_bool_t setup_rc;

                        /* resumee: [... initial_func]  (currently actually: [initial_func]) */

                        duk_push_undefined((duk_context *) resumee);
                        tv = &thr->heap->lj.value1;
                        duk_push_tval((duk_context *) resumee, tv);

                        /* resumee: [... initial_func undefined(= this) resume_value ] */

                        call_flags = DUK_CALL_FLAG_IS_RESUME;  /* is resume, not a tail call */

                        setup_rc = duk_handle_ecma_call_setup(resumee,
                                                              1,              /* num_stack_args */
                                                              call_flags);    /* call_flags */
                        if (setup_rc == 0) {
                                /* Shouldn't happen but check anyway. */
                                DUK_ERROR_INTERNAL_DEFMSG(thr);
                        }

                        resumee->resumer = thr;
                        resumee->state = DUK_HTHREAD_STATE_RUNNING;
                        thr->state = DUK_HTHREAD_STATE_RESUMED;
                        DUK_HEAP_SWITCH_THREAD(thr->heap, resumee);
#if 0
                        thr = resumee;  /* not needed, as we exit right away */
#endif
                        DUK_DD(DUK_DDPRINT("-> resume with a value, restart execution in resumee"));
                        retval = DUK__LONGJMP_RESTART;
                        goto wipe_and_return;
                }
                DUK_UNREACHABLE();
                break;  /* never here */
        }

        case DUK_LJ_TYPE_YIELD: {
                /*
                 *  Currently only allowed only if yielding thread has only
                 *  Ecmascript activations (except for the Duktape.Thread.yield()
                 *  call at the callstack top) and none of them constructor
                 *  calls.
                 *
                 *  This excludes the 'entry' thread which will always have
                 *  a preventcount > 0.
                 */

                duk_hthread *resumer;

                /* duk_bi_duk_object_yield() and duk_bi_duk_object_resume() ensure all of these are met */

                DUK_ASSERT(thr != entry_thread);                                                                             /* Duktape.Thread.yield() should prevent */
                DUK_ASSERT(thr->state == DUK_HTHREAD_STATE_RUNNING);                                                         /* unchanged from Duktape.Thread.yield() */
                DUK_ASSERT(thr->callstack_top >= 2);                                                                         /* Ecmascript activation + Duktape.Thread.yield() activation */
                DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1) != NULL &&
                           DUK_HOBJECT_IS_NATIVEFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1)) &&
                           ((duk_hnativefunction *) DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1))->func == duk_bi_thread_yield);
                DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 2) != NULL &&
                           DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 2)));      /* an Ecmascript function */
                DUK_ASSERT_DISABLE((thr->callstack + thr->callstack_top - 2)->idx_retval >= 0);                              /* unsigned */

                resumer = thr->resumer;

                DUK_ASSERT(resumer != NULL);
                DUK_ASSERT(resumer->state == DUK_HTHREAD_STATE_RESUMED);                                                     /* written by a previous RESUME handling */
                DUK_ASSERT(resumer->callstack_top >= 2);                                                                     /* Ecmascript activation + Duktape.Thread.resume() activation */
                DUK_ASSERT(DUK_ACT_GET_FUNC(resumer->callstack + resumer->callstack_top - 1) != NULL &&
                           DUK_HOBJECT_IS_NATIVEFUNCTION(DUK_ACT_GET_FUNC(resumer->callstack + resumer->callstack_top - 1)) &&
                           ((duk_hnativefunction *) DUK_ACT_GET_FUNC(resumer->callstack + resumer->callstack_top - 1))->func == duk_bi_thread_resume);
                DUK_ASSERT(DUK_ACT_GET_FUNC(resumer->callstack + resumer->callstack_top - 2) != NULL &&
                           DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(resumer->callstack + resumer->callstack_top - 2)));        /* an Ecmascript function */
                DUK_ASSERT_DISABLE((resumer->callstack + resumer->callstack_top - 2)->idx_retval >= 0);                      /* unsigned */

                if (thr->heap->lj.iserror) {
                        thr->state = DUK_HTHREAD_STATE_YIELDED;
                        thr->resumer = NULL;
                        resumer->state = DUK_HTHREAD_STATE_RUNNING;
                        DUK_HEAP_SWITCH_THREAD(thr->heap, resumer);
                        thr = resumer;

                        thr->heap->lj.type = DUK_LJ_TYPE_THROW;
                        /* lj.value1 is already set */
                        DUK_ASSERT(thr->heap->lj.iserror);  /* already set */

                        DUK_DD(DUK_DDPRINT("-> yield an error, converted to a throw in the resumer, propagate"));
                        goto check_longjmp;
                } else {
                        duk__handle_yield(thr, resumer, resumer->callstack_top - 2, &thr->heap->lj.value1);

                        thr->state = DUK_HTHREAD_STATE_YIELDED;
                        thr->resumer = NULL;
                        resumer->state = DUK_HTHREAD_STATE_RUNNING;
                        DUK_HEAP_SWITCH_THREAD(thr->heap, resumer);
#if 0
                        thr = resumer;  /* not needed, as we exit right away */
#endif

                        DUK_DD(DUK_DDPRINT("-> yield a value, restart execution in resumer"));
                        retval = DUK__LONGJMP_RESTART;
                        goto wipe_and_return;
                }
                DUK_UNREACHABLE();
                break;  /* never here */
        }

        case DUK_LJ_TYPE_THROW: {
                /*
                 *  Three possible outcomes:
                 *    * A try or finally catcher is found => resume there.
                 *      (or)
                 *    * The error propagates to the bytecode executor entry
                 *      level (and we're in the entry thread) => rethrow
                 *      with a new longjmp(), after restoring the previous
                 *      catchpoint.
                 *    * The error is not caught in the current thread, so
                 *      the thread finishes with an error.  This works like
                 *      a yielded error, except that the thread is finished
                 *      and can no longer be resumed.  (There is always a
                 *      resumer in this case.)
                 *
                 *  Note: until we hit the entry level, there can only be
                 *  Ecmascript activations.
                 */

                duk_catcher *cat;
                duk_hthread *resumer;

                cat = thr->catchstack + thr->catchstack_top - 1;
                while (cat >= thr->catchstack) {
                        if (thr == entry_thread &&
                            cat->callstack_index < entry_callstack_index) {
                                /* entry level reached */
                                break;
                        }

                        if (DUK_CAT_HAS_CATCH_ENABLED(cat)) {
                                DUK_ASSERT(DUK_CAT_GET_TYPE(cat) == DUK_CAT_TYPE_TCF);

                                duk__handle_catch(thr,
                                                  cat - thr->catchstack,
                                                  &thr->heap->lj.value1,
                                                  DUK_LJ_TYPE_THROW);

                                DUK_DD(DUK_DDPRINT("-> throw caught by a 'catch' clause, restart execution"));
                                retval = DUK__LONGJMP_RESTART;
                                goto wipe_and_return;
                        }

                        if (DUK_CAT_HAS_FINALLY_ENABLED(cat)) {
                                DUK_ASSERT(DUK_CAT_GET_TYPE(cat) == DUK_CAT_TYPE_TCF);
                                DUK_ASSERT(!DUK_CAT_HAS_CATCH_ENABLED(cat));

                                duk__handle_finally(thr,
                                                    cat - thr->catchstack,
                                                    &thr->heap->lj.value1,
                                                    DUK_LJ_TYPE_THROW);

                                DUK_DD(DUK_DDPRINT("-> throw caught by a 'finally' clause, restart execution"));
                                retval = DUK__LONGJMP_RESTART;
                                goto wipe_and_return;
                        }

                        cat--;
                }

                if (thr == entry_thread) {
                        /* not caught by anything before entry level; rethrow and let the
                         * final catcher unwind everything
                         */
#if 0
                        duk_hthread_catchstack_unwind(thr, (cat - thr->catchstack) + 1);  /* leave 'cat' as top catcher (also works if catchstack exhausted) */
                        duk_hthread_callstack_unwind(thr, entry_callstack_index + 1);

#endif
                        DUK_D(DUK_DPRINT("-> throw propagated up to entry level, rethrow and exit bytecode executor"));
                        retval = DUK__LONGJMP_RETHROW;
                        goto just_return;
                        /* Note: MUST NOT wipe_and_return here, as heap->lj must remain intact */
                }

                DUK_DD(DUK_DDPRINT("-> throw not caught by current thread, yield error to resumer and recheck longjmp"));

                /* not caught by current thread, thread terminates (yield error to resumer);
                 * note that this may cause a cascade if the resumer terminates with an uncaught
                 * exception etc (this is OK, but needs careful testing)
                 */

                DUK_ASSERT(thr->resumer != NULL);
                DUK_ASSERT(thr->resumer->callstack_top >= 2);  /* Ecmascript activation + Duktape.Thread.resume() activation */
                DUK_ASSERT(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 1) != NULL &&
                           DUK_HOBJECT_IS_NATIVEFUNCTION(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 1)) &&
                           ((duk_hnativefunction *) DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 1))->func == duk_bi_thread_resume);  /* Duktape.Thread.resume() */
                DUK_ASSERT(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 2) != NULL &&
                           DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 2)));  /* an Ecmascript function */

                resumer = thr->resumer;

                /* reset longjmp */

                DUK_ASSERT(thr->heap->lj.type == DUK_LJ_TYPE_THROW);  /* already set */
                /* lj.value1 already set */

                duk_hthread_terminate(thr);  /* updates thread state, minimizes its allocations */
                DUK_ASSERT(thr->state == DUK_HTHREAD_STATE_TERMINATED);

                thr->resumer = NULL;
                resumer->state = DUK_HTHREAD_STATE_RUNNING;
                DUK_HEAP_SWITCH_THREAD(thr->heap, resumer);
                thr = resumer;
                goto check_longjmp;
        }

        case DUK_LJ_TYPE_BREAK:  /* pseudotypes, not used in actual longjmps */
        case DUK_LJ_TYPE_CONTINUE:
        case DUK_LJ_TYPE_RETURN:
        case DUK_LJ_TYPE_NORMAL:
        default: {
                /* should never happen, but be robust */
                DUK_D(DUK_DPRINT("caught unknown longjmp type %ld, treat as internal error", (long) thr->heap->lj.type));
                goto convert_to_internal_error;
        }

        }  /* end switch */

        DUK_UNREACHABLE();

 wipe_and_return:
        /* this is not strictly necessary, but helps debugging */
        thr->heap->lj.type = DUK_LJ_TYPE_UNKNOWN;
        thr->heap->lj.iserror = 0;

        DUK_TVAL_SET_UNDEFINED_UPDREF(thr, &thr->heap->lj.value1);  /* side effects */
        DUK_TVAL_SET_UNDEFINED_UPDREF(thr, &thr->heap->lj.value2);  /* side effects */

 just_return:
        return retval;

 convert_to_internal_error:
        /* This could also be thrown internally (set the error, goto check_longjmp),
         * but it's better for internal errors to bubble outwards so that we won't
         * infinite loop in this catchpoint.
         */
        DUK_ERROR_INTERNAL_DEFMSG(thr);
        DUK_UNREACHABLE();
        return retval;
}

/* Handle a BREAK/CONTINUE opcode.  Avoid using longjmp() for BREAK/CONTINUE
 * handling because it has a measurable performance impact in ordinary
 * environments and an extreme impact in Emscripten (GH-342).
 */
DUK_LOCAL void duk__handle_break_or_continue(duk_hthread *thr,
                                             duk_uint_t label_id,
                                             duk_small_uint_t lj_type) {
        duk_catcher *cat;
        duk_size_t orig_callstack_index;

        DUK_ASSERT(thr != NULL);

        /*
         *  Find a matching label catcher or 'finally' catcher in
         *  the same function.
         *
         *  A label catcher must always exist and will match unless
         *  a 'finally' captures the break/continue first.  It is the
         *  compiler's responsibility to ensure that labels are used
         *  correctly.
         */

        /* Note: thr->catchstack_top may be 0, so that cat < thr->catchstack
         * initially.  This is OK and intended.
         */
        cat = thr->catchstack + thr->catchstack_top - 1;
        DUK_ASSERT(thr->callstack_top > 0);
        orig_callstack_index = thr->callstack_top - 1;

        DUK_DDD(DUK_DDDPRINT("handling break/continue with label=%ld, callstack index=%ld",
                             (long) label_id, (long) cat->callstack_index));

        while (cat >= thr->catchstack) {
                if (cat->callstack_index != orig_callstack_index) {
                        break;
                }
                DUK_DDD(DUK_DDDPRINT("considering catcher %ld: type=%ld label=%ld",
                                     (long) (cat - thr->catchstack),
                                     (long) DUK_CAT_GET_TYPE(cat),
                                     (long) DUK_CAT_GET_LABEL(cat)));

                if (DUK_CAT_GET_TYPE(cat) == DUK_CAT_TYPE_TCF &&
                    DUK_CAT_HAS_FINALLY_ENABLED(cat)) {
                        duk_size_t cat_idx;
                        duk_tval tv_tmp;

                        cat_idx = (duk_size_t) (cat - thr->catchstack);  /* get before side effects */

                        DUK_TVAL_SET_FASTINT_U32(&tv_tmp, (duk_uint32_t) label_id);
                        duk__handle_finally(thr, cat_idx, &tv_tmp, lj_type);

                        DUK_DD(DUK_DDPRINT("-> break/continue caught by 'finally', restart execution"));
                        return;
                }
                if (DUK_CAT_GET_TYPE(cat) == DUK_CAT_TYPE_LABEL &&
                    (duk_uint_t) DUK_CAT_GET_LABEL(cat) == label_id) {
                        duk_size_t cat_idx;

                        cat_idx = (duk_size_t) (cat - thr->catchstack);
                        duk__handle_label(thr, cat_idx, lj_type);

                        DUK_DD(DUK_DDPRINT("-> break/continue caught by a label catcher (in the same function), restart execution"));
                        return;
                }
                cat--;
        }

        /* should never happen, but be robust */
        DUK_D(DUK_DPRINT("-> break/continue not caught by anything in the current function (should never happen), throw internal error"));
        DUK_ERROR_INTERNAL_DEFMSG(thr);
        return;
}

/* Handle a RETURN opcode.  Avoid using longjmp() for return handling because
 * it has a measurable performance impact in ordinary environments and an extreme
 * impact in Emscripten (GH-342).  Return value is on value stack top.
 */
DUK_LOCAL duk_small_uint_t duk__handle_return(duk_hthread *thr,
                                              duk_hthread *entry_thread,
                                              duk_size_t entry_callstack_top) {
        duk_tval *tv1;
        duk_tval *tv2;
        duk_hthread *resumer;
        duk_catcher *cat;
        duk_size_t new_cat_top;
        duk_size_t orig_callstack_index;

        /* We can directly access value stack here. */

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(entry_thread != NULL);
        DUK_ASSERT(thr->valstack_top - 1 >= thr->valstack_bottom);
        tv1 = thr->valstack_top - 1;
        DUK_TVAL_CHKFAST_INPLACE(tv1);  /* fastint downgrade check for return values */

        /*
         *  Four possible outcomes:
         *
         *    1. A 'finally' in the same function catches the 'return'.
         *       It may continue to propagate when 'finally' is finished,
         *       or it may be neutralized by 'finally' (both handled by
         *       ENDFIN).
         *
         *    2. The return happens at the entry level of the bytecode
         *       executor, so return from the executor (in C stack).
         *
         *    3. There is a calling (Ecmascript) activation in the call
         *       stack => return to it, in the same executor instance.
         *
         *    4. There is no calling activation, and the thread is
         *       terminated.  There is always a resumer in this case,
         *       which gets the return value similarly to a 'yield'
         *       (except that the current thread can no longer be
         *       resumed).
         */

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(thr->callstack_top >= 1);
        DUK_ASSERT(thr->catchstack != NULL);

        /* XXX: does not work if thr->catchstack is NULL */
        /* XXX: does not work if thr->catchstack is allocated but lowest pointer */

        cat = thr->catchstack + thr->catchstack_top - 1;  /* may be < thr->catchstack initially */
        DUK_ASSERT(thr->callstack_top > 0);  /* ensures callstack_top - 1 >= 0 */
        orig_callstack_index = thr->callstack_top - 1;

        while (cat >= thr->catchstack) {
                if (cat->callstack_index != orig_callstack_index) {
                        break;
                }
                if (DUK_CAT_GET_TYPE(cat) == DUK_CAT_TYPE_TCF &&
                    DUK_CAT_HAS_FINALLY_ENABLED(cat)) {
                        duk_size_t cat_idx;

                        cat_idx = (duk_size_t) (cat - thr->catchstack);  /* get before side effects */

                        DUK_ASSERT(thr->valstack_top - 1 >= thr->valstack_bottom);
                        duk__handle_finally(thr, cat_idx, thr->valstack_top - 1, DUK_LJ_TYPE_RETURN);

                        DUK_DD(DUK_DDPRINT("-> return caught by 'finally', restart execution"));
                        return DUK__RETHAND_RESTART;
                }
                cat--;
        }
        /* If out of catchstack, cat = thr->catchstack - 1;
         * new_cat_top will be 0 in that case.
         */
        new_cat_top = (duk_size_t) ((cat + 1) - thr->catchstack);
        cat = NULL;  /* avoid referencing, invalidated */

        DUK_DDD(DUK_DDDPRINT("no catcher in catch stack, return to calling activation / yield"));

        if (thr == entry_thread &&
            thr->callstack_top == entry_callstack_top) {
                /* Return to the bytecode executor caller which will unwind stacks.
                 * Return value is already on the stack top: [ ... retval ].
                 */

                /* XXX: could unwind catchstack here, so that call handling
                 * didn't need to do that?
                 */
                DUK_DDD(DUK_DDDPRINT("-> return propagated up to entry level, exit bytecode executor"));
                return DUK__RETHAND_FINISHED;
        }

        if (thr->callstack_top >= 2) {
                /* There is a caller; it MUST be an Ecmascript caller (otherwise it would
                 * match entry level check)
                 */

                DUK_DDD(DUK_DDDPRINT("return to Ecmascript caller, idx_retval=%ld, lj_value1=%!T",
                                     (long) (thr->callstack + thr->callstack_top - 2)->idx_retval,
                                     (duk_tval *) &thr->heap->lj.value1));

                DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 2)));   /* must be ecmascript */

                tv1 = thr->valstack + (thr->callstack + thr->callstack_top - 2)->idx_retval;
                DUK_ASSERT(thr->valstack_top - 1 >= thr->valstack_bottom);
                tv2 = thr->valstack_top - 1;
                DUK_TVAL_SET_TVAL_UPDREF(thr, tv1, tv2);  /* side effects */

                DUK_DDD(DUK_DDDPRINT("return value at idx_retval=%ld is %!T",
                                     (long) (thr->callstack + thr->callstack_top - 2)->idx_retval,
                                     (duk_tval *) (thr->valstack + (thr->callstack + thr->callstack_top - 2)->idx_retval)));

                duk_hthread_catchstack_unwind(thr, new_cat_top);  /* leave 'cat' as top catcher (also works if catchstack exhausted) */
                duk_hthread_callstack_unwind(thr, thr->callstack_top - 1);
                duk__reconfig_valstack_ecma_return(thr, thr->callstack_top - 1);

                DUK_DD(DUK_DDPRINT("-> return not intercepted, restart execution in caller"));
                return DUK__RETHAND_RESTART;
        }

        DUK_DD(DUK_DDPRINT("no calling activation, thread finishes (similar to yield)"));

        DUK_ASSERT(thr->resumer != NULL);
        DUK_ASSERT(thr->resumer->callstack_top >= 2);  /* Ecmascript activation + Duktape.Thread.resume() activation */
        DUK_ASSERT(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 1) != NULL &&
                   DUK_HOBJECT_IS_NATIVEFUNCTION(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 1)) &&
                   ((duk_hnativefunction *) DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 1))->func == duk_bi_thread_resume);  /* Duktape.Thread.resume() */
        DUK_ASSERT(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 2) != NULL &&
                   DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->resumer->callstack + thr->resumer->callstack_top - 2)));  /* an Ecmascript function */
        DUK_ASSERT_DISABLE((thr->resumer->callstack + thr->resumer->callstack_top - 2)->idx_retval >= 0);                /* unsigned */
        DUK_ASSERT(thr->state == DUK_HTHREAD_STATE_RUNNING);
        DUK_ASSERT(thr->resumer->state == DUK_HTHREAD_STATE_RESUMED);

        resumer = thr->resumer;

        /* Share yield longjmp handler. */
        DUK_ASSERT(thr->valstack_top - 1 >= thr->valstack_bottom);
        duk__handle_yield(thr, resumer, resumer->callstack_top - 2, thr->valstack_top - 1);

        duk_hthread_terminate(thr);  /* updates thread state, minimizes its allocations */
        DUK_ASSERT(thr->state == DUK_HTHREAD_STATE_TERMINATED);

        thr->resumer = NULL;
        resumer->state = DUK_HTHREAD_STATE_RUNNING;
        DUK_HEAP_SWITCH_THREAD(thr->heap, resumer);
#if 0
        thr = resumer;  /* not needed */
#endif

        DUK_DD(DUK_DDPRINT("-> return not caught, thread terminated; handle like yield, restart execution in resumer"));
        return DUK__RETHAND_RESTART;
}

/*
 *  Executor interrupt handling
 *
 *  The handler is called whenever the interrupt countdown reaches zero
 *  (or below).  The handler must perform whatever checks are activated,
 *  e.g. check for cumulative step count to impose an execution step
 *  limit or check for breakpoints or other debugger interaction.
 *
 *  When the actions are done, the handler must reinit the interrupt
 *  init and counter values.  The 'init' value must indicate how many
 *  bytecode instructions are executed before the next interrupt.  The
 *  counter must interface with the bytecode executor loop.  Concretely,
 *  the new init value is normally one higher than the new counter value.
 *  For instance, to execute exactly one bytecode instruction the init
 *  value is set to 1 and the counter to 0.  If an error is thrown by the
 *  interrupt handler, the counters are set to the same value (e.g. both
 *  to 0 to cause an interrupt when the next bytecode instruction is about
 *  to be executed after error handling).
 *
 *  Maintaining the init/counter value properly is important for accurate
 *  behavior.  For instance, executor step limit needs a cumulative step
 *  count which is simply computed as a sum of 'init' values.  This must
 *  work accurately even when single stepping.
 */

#if defined(DUK_USE_INTERRUPT_COUNTER)

#define DUK__INT_NOACTION    0    /* no specific action, resume normal execution */
#define DUK__INT_RESTART     1    /* must "goto restart_execution", e.g. breakpoints changed */

#if defined(DUK_USE_DEBUGGER_SUPPORT)
DUK_LOCAL void duk__interrupt_handle_debugger(duk_hthread *thr, duk_bool_t *out_immediate, duk_small_uint_t *out_interrupt_retval) {
        duk_context *ctx;
        duk_activation *act;
        duk_breakpoint *bp;
        duk_breakpoint **bp_active;
        duk_uint_fast32_t line = 0;
        duk_bool_t process_messages;
        duk_bool_t processed_messages = 0;

        DUK_ASSERT(thr->heap->dbg_processing == 0);  /* don't re-enter e.g. during Eval */

        ctx = (duk_context *) thr;
        act = thr->callstack + thr->callstack_top - 1;

        /* It might seem that replacing 'thr->heap' with just 'heap' below
         * might be a good idea, but it increases code size slightly
         * (probably due to unnecessary spilling) at least on x64.
         */

        /*
         *  Breakpoint and step state checks
         */

        if (act->flags & DUK_ACT_FLAG_BREAKPOINT_ACTIVE ||
            (thr->heap->dbg_step_thread == thr &&
             thr->heap->dbg_step_csindex == thr->callstack_top - 1)) {
                line = duk_debug_curr_line(thr);

                if (act->prev_line != line) {
                        /* Stepped?  Step out is handled by callstack unwind. */
                        if ((thr->heap->dbg_step_type == DUK_STEP_TYPE_INTO ||
                             thr->heap->dbg_step_type == DUK_STEP_TYPE_OVER) &&
                            (thr->heap->dbg_step_thread == thr) &&
                            (thr->heap->dbg_step_csindex == thr->callstack_top - 1) &&
                            (line != thr->heap->dbg_step_startline)) {
                                DUK_D(DUK_DPRINT("STEP STATE TRIGGERED PAUSE at line %ld",
                                                 (long) line));

                                DUK_HEAP_SET_PAUSED(thr->heap);
                        }

                        /* Check for breakpoints only on line transition.
                         * Breakpoint is triggered when we enter the target
                         * line from a different line, and the previous line
                         * was within the same function.
                         *
                         * This condition is tricky: the condition used to be
                         * that transition to -or across- the breakpoint line
                         * triggered the breakpoint.  This seems intuitively
                         * better because it handles breakpoints on lines with
                         * no emitted opcodes; but this leads to the issue
                         * described in: https://github.com/svaarala/duktape/issues/263.
                         */
                        bp_active = thr->heap->dbg_breakpoints_active;
                        for (;;) {
                                bp = *bp_active++;
                                if (bp == NULL) {
                                        break;
                                }

                                DUK_ASSERT(bp->filename != NULL);
                                if (act->prev_line != bp->line && line == bp->line) {
                                        DUK_D(DUK_DPRINT("BREAKPOINT TRIGGERED at %!O:%ld",
                                                         (duk_heaphdr *) bp->filename, (long) bp->line));

                                        DUK_HEAP_SET_PAUSED(thr->heap);
                                }
                        }
                } else {
                        ;
                }

                act->prev_line = line;
        }

        /*
         *  Rate limit check for sending status update or peeking into
         *  the debug transport.  Both can be expensive operations that
         *  we don't want to do on every opcode.
         *
         *  Making sure the interval remains reasonable on a wide variety
         *  of targets and bytecode is difficult without a timestamp, so
         *  we use a Date-provided timestamp for the rate limit check.
         *  But since it's also expensive to get a timestamp, a bytecode
         *  counter is used to rate limit getting timestamps.
         */

        process_messages = 0;
        if (thr->heap->dbg_state_dirty || thr->heap->dbg_paused || thr->heap->dbg_detaching) {
                /* Enter message processing loop for sending Status notifys and
                 * to finish a pending detach.
                 */
                process_messages = 1;
        }

        /* XXX: remove heap->dbg_exec_counter, use heap->inst_count_interrupt instead? */
        thr->heap->dbg_exec_counter += thr->interrupt_init;
        if (thr->heap->dbg_exec_counter - thr->heap->dbg_last_counter >= DUK_HEAP_DBG_RATELIMIT_OPCODES) {
                /* Overflow of the execution counter is fine and doesn't break
                 * anything here.
                 */

                duk_double_t now, diff_last;

                thr->heap->dbg_last_counter = thr->heap->dbg_exec_counter;
                now = DUK_USE_DATE_GET_NOW(ctx);

                diff_last = now - thr->heap->dbg_last_time;
                if (diff_last < 0.0 || diff_last >= (duk_double_t) DUK_HEAP_DBG_RATELIMIT_MILLISECS) {
                        /* Negative value checked so that a "time jump" works
                         * reasonably.
                         *
                         * Same interval is now used for status sending and
                         * peeking.
                         */

                        thr->heap->dbg_last_time = now;
                        thr->heap->dbg_state_dirty = 1;
                        process_messages = 1;
                }
        }

        /*
         *  Process messages and send status if necessary.
         *
         *  If we're paused, we'll block for new messages.  If we're not
         *  paused, we'll process anything we can peek but won't block
         *  for more.  Detach (and re-attach) handling is all localized
         *  to duk_debug_process_messages() too.
         *
         *  Debugger writes outside the message loop may cause debugger
         *  detach1 phase to run, after which dbg_read_cb == NULL and
         *  dbg_detaching != 0.  The message loop will finish the detach
         *  by running detach2 phase, so enter the message loop also when
         *  detaching.
         */

        act = NULL;  /* may be changed */
        if (process_messages) {
                DUK_ASSERT(thr->heap->dbg_processing == 0);
                processed_messages = duk_debug_process_messages(thr, 0 /*no_block*/);
                DUK_ASSERT(thr->heap->dbg_processing == 0);
        }

        /* Continue checked execution if there are breakpoints or we're stepping.
         * Also use checked execution if paused flag is active - it shouldn't be
         * because the debug message loop shouldn't terminate if it was.  Step out
         * is handled by callstack unwind and doesn't need checked execution.
         * Note that debugger may have detached due to error or explicit request
         * above, so we must recheck attach status.
         */

        if (DUK_HEAP_IS_DEBUGGER_ATTACHED(thr->heap)) {
                act = thr->callstack + thr->callstack_top - 1;  /* relookup, may have changed */
                if (act->flags & DUK_ACT_FLAG_BREAKPOINT_ACTIVE ||
                    ((thr->heap->dbg_step_type == DUK_STEP_TYPE_INTO ||
                      thr->heap->dbg_step_type == DUK_STEP_TYPE_OVER) &&
                     thr->heap->dbg_step_thread == thr &&
                     thr->heap->dbg_step_csindex == thr->callstack_top - 1) ||
                     thr->heap->dbg_paused) {
                        *out_immediate = 1;
                }

                /* If we processed any debug messages breakpoints may have
                 * changed; restart execution to re-check active breakpoints.
                 */
                if (processed_messages) {
                        DUK_D(DUK_DPRINT("processed debug messages, restart execution to recheck possibly changed breakpoints"));
                        *out_interrupt_retval = DUK__INT_RESTART;
                }
        } else {
                DUK_D(DUK_DPRINT("debugger became detached, resume normal execution"));
        }
}
#endif  /* DUK_USE_DEBUGGER_SUPPORT */

DUK_LOCAL duk_small_uint_t duk__executor_interrupt(duk_hthread *thr) {
        duk_int_t ctr;
        duk_activation *act;
        duk_hcompiledfunction *fun;
        duk_bool_t immediate = 0;
        duk_small_uint_t retval;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(thr->heap != NULL);
        DUK_ASSERT(thr->callstack != NULL);
        DUK_ASSERT(thr->callstack_top > 0);

#if defined(DUK_USE_DEBUG)
        thr->heap->inst_count_interrupt += thr->interrupt_init;
        DUK_DD(DUK_DDPRINT("execution interrupt, counter=%ld, init=%ld, "
                           "instruction counts: executor=%ld, interrupt=%ld",
                           (long) thr->interrupt_counter, (long) thr->interrupt_init,
                           (long) thr->heap->inst_count_exec, (long) thr->heap->inst_count_interrupt));
#endif

        retval = DUK__INT_NOACTION;
        ctr = DUK_HTHREAD_INTCTR_DEFAULT;

        /*
         *  Avoid nested calls.  Concretely this happens during debugging, e.g.
         *  when we eval() an expression.
         *
         *  Also don't interrupt if we're currently doing debug processing
         *  (which can be initiated outside the bytecode executor) as this
         *  may cause the debugger to be called recursively.  Check required
         *  for correct operation of throw intercept and other "exotic" halting
         * scenarios.
         */

#if defined(DUK_USE_DEBUGGER_SUPPORT)
        if (DUK_HEAP_HAS_INTERRUPT_RUNNING(thr->heap) || thr->heap->dbg_processing) {
#else
        if (DUK_HEAP_HAS_INTERRUPT_RUNNING(thr->heap)) {
#endif
                DUK_DD(DUK_DDPRINT("nested executor interrupt, ignoring"));

                /* Set a high interrupt counter; the original executor
                 * interrupt invocation will rewrite before exiting.
                 */
                thr->interrupt_init = ctr;
                thr->interrupt_counter = ctr - 1;
                return DUK__INT_NOACTION;
        }
        DUK_HEAP_SET_INTERRUPT_RUNNING(thr->heap);

        act = thr->callstack + thr->callstack_top - 1;

        fun = (duk_hcompiledfunction *) DUK_ACT_GET_FUNC(act);
        DUK_ASSERT(DUK_HOBJECT_HAS_COMPILEDFUNCTION((duk_hobject *) fun));

        DUK_UNREF(fun);

#if defined(DUK_USE_EXEC_TIMEOUT_CHECK)
        /*
         *  Execution timeout check
         */

        if (DUK_USE_EXEC_TIMEOUT_CHECK(thr->heap->heap_udata)) {
                /* Keep throwing an error whenever we get here.  The unusual values
                 * are set this way because no instruction is ever executed, we just
                 * throw an error until all try/catch/finally and other catchpoints
                 * have been exhausted.  Duktape/C code gets control at each protected
                 * call but whenever it enters back into Duktape the RangeError gets
                 * raised.  User exec timeout check must consistently indicate a timeout
                 * until we've fully bubbled out of Duktape.
                 */
                DUK_D(DUK_DPRINT("execution timeout, throwing a RangeError"));
                thr->interrupt_init = 0;
                thr->interrupt_counter = 0;
                DUK_HEAP_CLEAR_INTERRUPT_RUNNING(thr->heap);
                DUK_ERROR_RANGE(thr, "execution timeout");
        }
#endif  /* DUK_USE_EXEC_TIMEOUT_CHECK */

#if defined(DUK_USE_DEBUGGER_SUPPORT)
        if (!thr->heap->dbg_processing &&
            (thr->heap->dbg_read_cb != NULL || thr->heap->dbg_detaching)) {
                /* Avoid recursive re-entry; enter when we're attached or
                 * detaching (to finish off the pending detach).
                 */
                duk__interrupt_handle_debugger(thr, &immediate, &retval);
                act = thr->callstack + thr->callstack_top - 1;  /* relookup if changed */
                DUK_UNREF(act);  /* 'act' is no longer accessed, scanbuild fix */
        }
#endif  /* DUK_USE_DEBUGGER_SUPPORT */

        /*
         *  Update the interrupt counter
         */

        if (immediate) {
                /* Cause an interrupt after executing one instruction. */
                ctr = 1;
        }

        /* The counter value is one less than the init value: init value should
         * indicate how many instructions are executed before interrupt.  To
         * execute 1 instruction (after interrupt handler return), counter must
         * be 0.
         */
        DUK_ASSERT(ctr >= 1);
        thr->interrupt_init = ctr;
        thr->interrupt_counter = ctr - 1;
        DUK_HEAP_CLEAR_INTERRUPT_RUNNING(thr->heap);

        return retval;
}
#endif  /* DUK_USE_INTERRUPT_COUNTER */

/*
 *  Debugger handling for executor restart
 *
 *  Check for breakpoints, stepping, etc, and figure out if we should execute
 *  in checked or normal mode.  Note that we can't do this when an activation
 *  is created, because breakpoint status (and stepping status) may change
 *  later, so we must recheck every time we're executing an activation.
 *  This primitive should be side effect free to avoid changes during check.
 */

#if defined(DUK_USE_DEBUGGER_SUPPORT)
DUK_LOCAL void duk__executor_recheck_debugger(duk_hthread *thr, duk_activation *act, duk_hcompiledfunction *fun) {
        duk_heap *heap;
        duk_tval *tv_tmp;
        duk_hstring *filename;
        duk_small_uint_t bp_idx;
        duk_breakpoint **bp_active;

        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(act != NULL);
        DUK_ASSERT(fun != NULL);

        heap = thr->heap;
        bp_active = heap->dbg_breakpoints_active;
        act->flags &= ~DUK_ACT_FLAG_BREAKPOINT_ACTIVE;

        tv_tmp = duk_hobject_find_existing_entry_tval_ptr(thr->heap, (duk_hobject *) fun, DUK_HTHREAD_STRING_FILE_NAME(thr));
        if (tv_tmp && DUK_TVAL_IS_STRING(tv_tmp)) {
                filename = DUK_TVAL_GET_STRING(tv_tmp);

                /* Figure out all active breakpoints.  A breakpoint is
                 * considered active if the current function's fileName
                 * matches the breakpoint's fileName, AND there is no
                 * inner function that has matching line numbers
                 * (otherwise a breakpoint would be triggered both
                 * inside and outside of the inner function which would
                 * be confusing).  Example:
                 *
                 *     function foo() {
                 *         print('foo');
                 *         function bar() {    <-.  breakpoints in these
                 *             print('bar');     |  lines should not affect
                 *         }                   <-'  foo() execution
                 *         bar();
                 *     }
                 *
                 * We need a few things that are only available when
                 * debugger support is enabled: (1) a line range for
                 * each function, and (2) access to the function
                 * template to access the inner functions (and their
                 * line ranges).
                 *
                 * It's important to have a narrow match for active
                 * breakpoints so that we don't enter checked execution
                 * when that's not necessary.  For instance, if we're
                 * running inside a certain function and there's
                 * breakpoint outside in (after the call site), we
                 * don't want to slow down execution of the function.
                 */

                for (bp_idx = 0; bp_idx < heap->dbg_breakpoint_count; bp_idx++) {
                        duk_breakpoint *bp = heap->dbg_breakpoints + bp_idx;
                        duk_hobject **funcs, **funcs_end;
                        duk_hcompiledfunction *inner_fun;
                        duk_bool_t bp_match;

                        if (bp->filename == filename &&
                            bp->line >= fun->start_line && bp->line <= fun->end_line) {
                                bp_match = 1;
                                DUK_DD(DUK_DDPRINT("breakpoint filename and line match: "
                                                   "%s:%ld vs. %s (line %ld vs. %ld-%ld)",
                                                   DUK_HSTRING_GET_DATA(bp->filename),
                                                   (long) bp->line,
                                                   DUK_HSTRING_GET_DATA(filename),
                                                   (long) bp->line,
                                                   (long) fun->start_line,
                                                   (long) fun->end_line));

                                funcs = DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(thr->heap, fun);
                                funcs_end = DUK_HCOMPILEDFUNCTION_GET_FUNCS_END(thr->heap, fun);
                                while (funcs != funcs_end) {
                                        inner_fun = (duk_hcompiledfunction *) *funcs;
                                        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION((duk_hobject *) inner_fun));
                                        if (bp->line >= inner_fun->start_line && bp->line <= inner_fun->end_line) {
                                                DUK_DD(DUK_DDPRINT("inner function masks ('captures') breakpoint"));
                                                bp_match = 0;
                                                break;
                                        }
                                        funcs++;
                                }

                                if (bp_match) {
                                        /* No need to check for size of bp_active list,
                                         * it's always larger than maximum number of
                                         * breakpoints.
                                         */
                                        act->flags |= DUK_ACT_FLAG_BREAKPOINT_ACTIVE;
                                        *bp_active = heap->dbg_breakpoints + bp_idx;
                                        bp_active++;
                                }
                        }
                }
        }

        *bp_active = NULL;  /* terminate */

        DUK_DD(DUK_DDPRINT("ACTIVE BREAKPOINTS: %ld", (long) (bp_active - thr->heap->dbg_breakpoints_active)));

        /* Force pause if we were doing "step into" in another activation. */
        if (thr->heap->dbg_step_thread != NULL &&
            thr->heap->dbg_step_type == DUK_STEP_TYPE_INTO &&
            (thr->heap->dbg_step_thread != thr ||
             thr->heap->dbg_step_csindex != thr->callstack_top - 1)) {
                DUK_D(DUK_DPRINT("STEP INTO ACTIVE, FORCE PAUSED"));
                DUK_HEAP_SET_PAUSED(thr->heap);
        }

        /* Force interrupt right away if we're paused or in "checked mode".
         * Step out is handled by callstack unwind.
         */
        if (act->flags & (DUK_ACT_FLAG_BREAKPOINT_ACTIVE) ||
            thr->heap->dbg_paused ||
            (thr->heap->dbg_step_type != DUK_STEP_TYPE_OUT &&
             thr->heap->dbg_step_csindex == thr->callstack_top - 1)) {
                /* We'll need to interrupt early so recompute the init
                 * counter to reflect the number of bytecode instructions
                 * executed so that step counts for e.g. debugger rate
                 * limiting are accurate.
                 */
                DUK_ASSERT(thr->interrupt_counter <= thr->interrupt_init);
                thr->interrupt_init = thr->interrupt_init - thr->interrupt_counter;
                thr->interrupt_counter = 0;
        }
}
#endif  /* DUK_USE_DEBUGGER_SUPPORT */

/*
 *  Ecmascript bytecode executor.
 *
 *  Resume execution for the current thread from its current activation.
 *  Returns when execution would return from the entry level activation,
 *  leaving a single return value on top of the stack.  Function calls
 *  and thread resumptions are handled internally.  If an error occurs,
 *  a longjmp() with type DUK_LJ_TYPE_THROW is called on the entry level
 *  setjmp() jmpbuf.
 *
 *  Ecmascript function calls and coroutine resumptions are handled
 *  internally (by the outer executor function) without recursive C calls.
 *  Other function calls are handled using duk_handle_call(), increasing
 *  C recursion depth.
 *
 *  Abrupt completions (= long control tranfers) are handled either
 *  directly by reconfiguring relevant stacks and restarting execution,
 *  or via a longjmp.  Longjmp-free handling is preferable for performance
 *  (especially Emscripten performance), and is used for: break, continue,
 *  and return.
 *
 *  For more detailed notes, see doc/execution.rst.
 *
 *  Also see doc/code-issues.rst for discussion of setjmp(), longjmp(),
 *  and volatile.
 */

/* Presence of 'fun' is config based, there's a marginal performance
 * difference and the best option is architecture dependent.
 */
#if defined(DUK_USE_EXEC_FUN_LOCAL)
#define DUK__FUN()          fun
#else
#define DUK__FUN()          ((duk_hcompiledfunction *) DUK_ACT_GET_FUNC((thr)->callstack + (thr)->callstack_top - 1))
#endif
#define DUK__STRICT()       (DUK_HOBJECT_HAS_STRICT((duk_hobject *) DUK__FUN()))

/* Reg/const access macros: these are very footprint and performance sensitive
 * so modify with care.
 */
#define DUK__REG(x)         (*(thr->valstack_bottom + (x)))
#define DUK__REGP(x)        (thr->valstack_bottom + (x))
#define DUK__CONST(x)       (*(consts + (x)))
#define DUK__CONSTP(x)      (consts + (x))
#if 0
#define DUK__REGCONST(x)    ((x) < DUK_BC_REGLIMIT ? DUK__REG((x)) : DUK__CONST((x) - DUK_BC_REGLIMIT))
#define DUK__REGCONSTP(x)   ((x) < DUK_BC_REGLIMIT ? DUK__REGP((x)) : DUK__CONSTP((x) - DUK_BC_REGLIMIT))
#define DUK__REGCONST(x)    *((((x) < DUK_BC_REGLIMIT ? thr->valstack_bottom : consts2) + (x)))
#define DUK__REGCONSTP(x)   (((x) < DUK_BC_REGLIMIT ? thr->valstack_bottom : consts2) + (x))
#endif
/* This macro works when a regconst field is 9 bits, [0,0x1ff].  Adding
 * DUK_LIKELY/DUK_UNLIKELY increases code footprint and doesn't seem to
 * improve performance on x64 (and actually harms performance in some tests).
 */
#define DUK__RCISREG(x)     (((x) & 0x100) == 0)
#define DUK__REGCONST(x)    (*((DUK__RCISREG((x)) ? thr->valstack_bottom : consts2) + (x)))
#define DUK__REGCONSTP(x)   ((DUK__RCISREG((x)) ? thr->valstack_bottom : consts2) + (x))

#ifdef DUK_USE_VERBOSE_EXECUTOR_ERRORS
#define DUK__INTERNAL_ERROR(msg)  do { \
                DUK_ERROR_INTERNAL(thr, (msg)); \
        } while (0)
#else
#define DUK__INTERNAL_ERROR(msg)  do { \
                goto internal_error; \
        } while (0)
#endif

#define DUK__SYNC_CURR_PC()  do { \
                duk_activation *act; \
                act = thr->callstack + thr->callstack_top - 1; \
                act->curr_pc = curr_pc; \
        } while (0)
#define DUK__SYNC_AND_NULL_CURR_PC()  do { \
                duk_activation *act; \
                act = thr->callstack + thr->callstack_top - 1; \
                act->curr_pc = curr_pc; \
                thr->ptr_curr_pc = NULL; \
        } while (0)

DUK_LOCAL void duk__handle_executor_error(duk_heap *heap,
                                          duk_hthread *entry_thread,
                                          duk_size_t entry_callstack_top,
                                          duk_int_t entry_call_recursion_depth,
                                          duk_jmpbuf *entry_jmpbuf_ptr) {
        duk_small_uint_t lj_ret;

        /* Longjmp callers are required to sync-and-null thr->ptr_curr_pc
         * before longjmp.
         */
        DUK_ASSERT(heap->curr_thread != NULL);
        DUK_ASSERT(heap->curr_thread->ptr_curr_pc == NULL);

        /* XXX: signalling the need to shrink check (only if unwound) */

        /* Must be restored here to handle e.g. yields properly. */
        heap->call_recursion_depth = entry_call_recursion_depth;

        /* Switch to caller's setjmp() catcher so that if an error occurs
         * during error handling, it is always propagated outwards instead
         * of causing an infinite loop in our own handler.
         */
        heap->lj.jmpbuf_ptr = (duk_jmpbuf *) entry_jmpbuf_ptr;

        lj_ret = duk__handle_longjmp(heap->curr_thread, entry_thread, entry_callstack_top);

        if (lj_ret == DUK__LONGJMP_RESTART) {
                /* Restart bytecode execution, possibly with a changed thread. */
                ;
        } else {
                /* Rethrow error to calling state. */
                DUK_ASSERT(lj_ret == DUK__LONGJMP_RETHROW);

                /* Longjmp handling has restored jmpbuf_ptr. */
                DUK_ASSERT(heap->lj.jmpbuf_ptr == entry_jmpbuf_ptr);

                /* Thread may have changed, e.g. YIELD converted to THROW. */
                duk_err_longjmp(heap->curr_thread);
                DUK_UNREACHABLE();
        }
}

/* Outer executor with setjmp/longjmp handling. */
DUK_INTERNAL void duk_js_execute_bytecode(duk_hthread *exec_thr) {
        /* Entry level info. */
        duk_hthread *entry_thread;
        duk_size_t entry_callstack_top;
        duk_int_t entry_call_recursion_depth;
        duk_jmpbuf *entry_jmpbuf_ptr;
        duk_jmpbuf our_jmpbuf;
        duk_heap *heap;

        DUK_ASSERT(exec_thr != NULL);
        DUK_ASSERT(exec_thr->heap != NULL);
        DUK_ASSERT(exec_thr->heap->curr_thread != NULL);
        DUK_ASSERT_REFCOUNT_NONZERO_HEAPHDR((duk_heaphdr *) exec_thr);
        DUK_ASSERT(exec_thr->callstack_top >= 1);  /* at least one activation, ours */
        DUK_ASSERT(DUK_ACT_GET_FUNC(exec_thr->callstack + exec_thr->callstack_top - 1) != NULL);
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(exec_thr->callstack + exec_thr->callstack_top - 1)));

        entry_thread = exec_thr;
        heap = entry_thread->heap;
        entry_callstack_top = entry_thread->callstack_top;
        entry_call_recursion_depth = entry_thread->heap->call_recursion_depth;
        entry_jmpbuf_ptr = entry_thread->heap->lj.jmpbuf_ptr;

        /*
         *  Note: we currently assume that the setjmp() catchpoint is
         *  not re-entrant (longjmp() cannot be called more than once
         *  for a single setjmp()).
         *
         *  See doc/code-issues.rst for notes on variable assignment
         *  before and after setjmp().
         */

        for (;;) {
                heap->lj.jmpbuf_ptr = &our_jmpbuf;
                DUK_ASSERT(heap->lj.jmpbuf_ptr != NULL);

#if defined(DUK_USE_CPP_EXCEPTIONS)
                try {
#else
                DUK_ASSERT(heap->lj.jmpbuf_ptr == &our_jmpbuf);
                if (DUK_SETJMP(our_jmpbuf.jb) == 0) {
#endif
                        /* Execute bytecode until returned or longjmp(). */
                        duk__js_execute_bytecode_inner(entry_thread, entry_callstack_top);

                        /* Successful return: restore jmpbuf and return to caller. */
                        heap->lj.jmpbuf_ptr = entry_jmpbuf_ptr;

                        return;
#if defined(DUK_USE_CPP_EXCEPTIONS)
                } catch (duk_internal_exception &exc) {
#else
                } else {
#endif
#if defined(DUK_USE_CPP_EXCEPTIONS)
                        DUK_UNREF(exc);
#endif
                        DUK_DDD(DUK_DDDPRINT("longjmp caught by bytecode executor"));

                        duk__handle_executor_error(heap,
                                                   entry_thread,
                                                   entry_callstack_top,
                                                   entry_call_recursion_depth,
                                                   entry_jmpbuf_ptr);
                }
#if defined(DUK_USE_CPP_EXCEPTIONS)
                catch (std::exception &exc) {
                        const char *what = exc.what();
                        if (!what) {
                                what = "unknown";
                        }
                        DUK_D(DUK_DPRINT("unexpected c++ std::exception (perhaps thrown by user code)"));
                        try {
                                DUK_ASSERT(heap->curr_thread != NULL);
                                DUK_ERROR_FMT1(heap->curr_thread, DUK_ERR_API_ERROR, "caught invalid c++ std::exception '%s' (perhaps thrown by user code)", what);
                        } catch (duk_internal_exception exc) {
                                DUK_D(DUK_DPRINT("caught api error thrown from unexpected c++ std::exception"));
                                DUK_UNREF(exc);
                                duk__handle_executor_error(heap,
                                                           entry_thread,
                                                           entry_callstack_top,
                                                           entry_call_recursion_depth,
                                                           entry_jmpbuf_ptr);
                        }
                } catch (...) {
                        DUK_D(DUK_DPRINT("unexpected c++ exception (perhaps thrown by user code)"));
                        try {
                                DUK_ASSERT(heap->curr_thread != NULL);
                                DUK_ERROR_API(heap->curr_thread, "caught invalid c++ exception (perhaps thrown by user code)");
                        } catch (duk_internal_exception exc) {
                                DUK_D(DUK_DPRINT("caught api error thrown from unexpected c++ exception"));
                                DUK_UNREF(exc);
                                duk__handle_executor_error(heap,
                                                           entry_thread,
                                                           entry_callstack_top,
                                                           entry_call_recursion_depth,
                                                           entry_jmpbuf_ptr);
                        }
                }
#endif
        }

        DUK_UNREACHABLE();
}

/* Inner executor, performance critical. */
DUK_LOCAL DUK_NOINLINE void duk__js_execute_bytecode_inner(duk_hthread *entry_thread, duk_size_t entry_callstack_top) {
        /* Current PC, accessed by other functions through thr->ptr_to_curr_pc.
         * Critical for performance.  It would be safest to make this volatile,
         * but that eliminates performance benefits; aliasing guarantees
         * should be enough though.
         */
        duk_instr_t *curr_pc;         /* bytecode has a stable pointer */

        /* Hot variables for interpretation.  Critical for performance,
         * but must add sparingly to minimize register shuffling.
         */
        duk_hthread *thr;             /* stable */
        duk_tval *consts;             /* stable */
        duk_tval *consts2;            /* stable; precalculated for faster lookups */
        duk_uint_fast32_t ins;
        /* 'funcs' is quite rarely used, so no local for it */
#if defined(DUK_USE_EXEC_FUN_LOCAL)
        duk_hcompiledfunction *fun;
#else
        /* 'fun' is quite rarely used, so no local for it */
#endif

#ifdef DUK_USE_INTERRUPT_COUNTER
        duk_int_t int_ctr;
#endif

#ifdef DUK_USE_ASSERTIONS
        duk_size_t valstack_top_base;    /* valstack top, should match before interpreting each op (no leftovers) */
#endif

        /*
         *  Restart execution by reloading thread state.
         *
         *  Note that 'thr' and any thread configuration may have changed,
         *  so all local variables are suspect and we need to reinitialize.
         *
         *  The number of local variables should be kept to a minimum: if
         *  the variables are spilled, they will need to be loaded from
         *  memory anyway.
         *
         *  Any 'goto restart_execution;' code path in opcode dispatch must
         *  ensure 'curr_pc' is synced back to act->curr_pc before the goto
         *  takes place.
         *
         *  The interpreter must be very careful with memory pointers, as
         *  many pointers are not guaranteed to be 'stable' and may be
         *  reallocated and relocated on-the-fly quite easily (e.g. by a
         *  memory allocation or a property access).
         *
         *  The following are assumed to have stable pointers:
         *    - the current thread
         *    - the current function
         *    - the bytecode, constant table, inner function table of the
         *      current function (as they are a part of the function allocation)
         *
         *  The following are assumed to have semi-stable pointers:
         *    - the current activation entry: stable as long as callstack
         *      is not changed (reallocated by growing or shrinking), or
         *      by any garbage collection invocation (through finalizers)
         *    - Note in particular that ANY DECREF can invalidate the
         *      activation pointer, so for the most part a fresh lookup
         *      is required
         *
         *  The following are not assumed to have stable pointers at all:
         *    - the value stack (registers) of the current thread
         *    - the catch stack of the current thread
         *
         *  See execution.rst for discussion.
         */

 restart_execution:

        /* Lookup current thread; use the stable 'entry_thread' for this to
         * avoid clobber warnings.  Any valid, reachable 'thr' value would be
         * fine for this, so using 'entry_thread' is just to silence warnings.
         */
        thr = entry_thread->heap->curr_thread;
        DUK_ASSERT(thr != NULL);
        DUK_ASSERT(thr->callstack_top >= 1);
        DUK_ASSERT(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1) != NULL);
        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(DUK_ACT_GET_FUNC(thr->callstack + thr->callstack_top - 1)));

        thr->ptr_curr_pc = &curr_pc;

        /* Relookup and initialize dispatch loop variables.  Debugger check. */
        {
                duk_activation *act;
#if !defined(DUK_USE_EXEC_FUN_LOCAL)
                duk_hcompiledfunction *fun;
#endif

                /* Assume interrupt init/counter are properly initialized here. */
                /* Assume that thr->valstack_bottom has been set-up before getting here. */

                act = thr->callstack + thr->callstack_top - 1;
                fun = (duk_hcompiledfunction *) DUK_ACT_GET_FUNC(act);
                DUK_ASSERT(fun != NULL);
                DUK_ASSERT(thr->valstack_top - thr->valstack_bottom == fun->nregs);
                consts = DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(thr->heap, fun);
                DUK_ASSERT(consts != NULL);
                consts2 = consts - DUK_BC_REGLIMIT;

#if defined(DUK_USE_DEBUGGER_SUPPORT)
                if (DUK_HEAP_IS_DEBUGGER_ATTACHED(thr->heap) && !thr->heap->dbg_processing) {
                        duk__executor_recheck_debugger(thr, act, fun);
                        act = thr->callstack + thr->callstack_top - 1;  /* relookup after side effects (no side effects currently however) */
                }
#endif  /* DUK_USE_DEBUGGER_SUPPORT */

#ifdef DUK_USE_ASSERTIONS
                valstack_top_base = (duk_size_t) (thr->valstack_top - thr->valstack);
#endif

                /* Set up curr_pc for opcode dispatch. */
                curr_pc = act->curr_pc;
        }

        DUK_DD(DUK_DDPRINT("restarting execution, thr %p, act idx %ld, fun %p,"
                           "consts %p, funcs %p, lev %ld, regbot %ld, regtop %ld, catchstack_top=%ld, "
                           "preventcount=%ld",
                           (void *) thr,
                           (long) (thr->callstack_top - 1),
                           (void *) DUK__FUN(),
                           (void *) DUK_HCOMPILEDFUNCTION_GET_CONSTS_BASE(thr->heap, DUK__FUN()),
                           (void *) DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(thr->heap, DUK__FUN()),
                           (long) (thr->callstack_top - 1),
                           (long) (thr->valstack_bottom - thr->valstack),
                           (long) (thr->valstack_top - thr->valstack),
                           (long) thr->catchstack_top,
                           (long) thr->callstack_preventcount));

        /* Dispatch loop. */

        for (;;) {
                DUK_ASSERT(thr->callstack_top >= 1);
                DUK_ASSERT(thr->valstack_top - thr->valstack_bottom == DUK__FUN()->nregs);
                DUK_ASSERT((duk_size_t) (thr->valstack_top - thr->valstack) == valstack_top_base);

                /* Executor interrupt counter check, used to implement breakpoints,
                 * debugging interface, execution timeouts, etc.  The counter is heap
                 * specific but is maintained in the current thread to make the check
                 * as fast as possible.  The counter is copied back to the heap struct
                 * whenever a thread switch occurs by the DUK_HEAP_SWITCH_THREAD() macro.
                 */
#if defined(DUK_USE_INTERRUPT_COUNTER)
                int_ctr = thr->interrupt_counter;
                if (DUK_LIKELY(int_ctr > 0)) {
                        thr->interrupt_counter = int_ctr - 1;
                } else {
                        /* Trigger at zero or below */
                        duk_small_uint_t exec_int_ret;

                        /* Write curr_pc back for the debugger. */
                        DUK_ASSERT(thr->callstack_top > 0);
                        {
                                duk_activation *act;
                                act = thr->callstack + thr->callstack_top - 1;
                                act->curr_pc = (duk_instr_t *) curr_pc;
                        }

                        /* Force restart caused by a function return; must recheck
                         * debugger breakpoints before checking line transitions,
                         * see GH-303.  Restart and then handle interrupt_counter
                         * zero again.
                         */
#if defined(DUK_USE_DEBUGGER_SUPPORT)
                        if (thr->heap->dbg_force_restart) {
                                DUK_DD(DUK_DDPRINT("dbg_force_restart flag forced restart execution"));  /* GH-303 */
                                thr->heap->dbg_force_restart = 0;
                                goto restart_execution;
                        }
#endif

                        exec_int_ret = duk__executor_interrupt(thr);
                        if (exec_int_ret == DUK__INT_RESTART) {
                                /* curr_pc synced back above */
                                goto restart_execution;
                        }
                }
#endif  /* DUK_USE_INTERRUPT_COUNTER */
#if defined(DUK_USE_INTERRUPT_COUNTER) && defined(DUK_USE_DEBUG)
                /* For cross-checking during development: ensure dispatch count
                 * matches cumulative interrupt counter init value sums.
                 */
                thr->heap->inst_count_exec++;
#endif

#if defined(DUK_USE_ASSERTIONS) || defined(DUK_USE_DEBUG)
                {
                        duk_activation *act;
                        act = thr->callstack + thr->callstack_top - 1;
                        DUK_ASSERT(curr_pc >= DUK_HCOMPILEDFUNCTION_GET_CODE_BASE(thr->heap, DUK__FUN()));
                        DUK_ASSERT(curr_pc < DUK_HCOMPILEDFUNCTION_GET_CODE_END(thr->heap, DUK__FUN()));
                        DUK_UNREF(act);  /* if debugging disabled */

                        DUK_DDD(DUK_DDDPRINT("executing bytecode: pc=%ld, ins=0x%08lx, op=%ld, valstack_top=%ld/%ld, nregs=%ld  -->  %!I",
                                             (long) (curr_pc - DUK_HCOMPILEDFUNCTION_GET_CODE_BASE(thr->heap, DUK__FUN())),
                                             (unsigned long) *curr_pc,
                                             (long) DUK_DEC_OP(*curr_pc),
                                             (long) (thr->valstack_top - thr->valstack),
                                             (long) (thr->valstack_end - thr->valstack),
                                             (long) (DUK__FUN() ? DUK__FUN()->nregs : -1),
                                             (duk_instr_t) *curr_pc));
                }
#endif

#if defined(DUK_USE_ASSERTIONS)
                /* Quite heavy assert: check valstack policy.  Improper
                 * shuffle instructions can write beyond valstack_top/end
                 * so this check catches them in the act.
                 */
                {
                        duk_tval *tv;
                        tv = thr->valstack_top;
                        while (tv != thr->valstack_end) {
                                DUK_ASSERT(DUK_TVAL_IS_UNDEFINED(tv));
                                tv++;
                        }
                }
#endif

                ins = *curr_pc++;

                /* Typing: use duk_small_(u)int_fast_t when decoding small
                 * opcode fields (op, A, B, C) and duk_(u)int_fast_t when
                 * decoding larger fields (e.g. BC which is 18 bits).  Use
                 * unsigned variant by default, signed when the value is used
                 * in signed arithmetic.  Using variable names such as 'a', 'b',
                 * 'c', 'bc', etc makes it easier to spot typing mismatches.
                 */

                /* XXX: the best typing needs to be validated by perf measurement:
                 * e.g. using a small type which is the cast to a larger duk_idx_t
                 * may be slower than declaring the variable as a duk_idx_t in the
                 * first place.
                 */

                /* XXX: use macros for the repetitive tval/refcount handling. */

                switch ((int) DUK_DEC_OP(ins)) {
                /* XXX: switch cast? */

                case DUK_OP_LDREG: {
                        duk_small_uint_fast_t a;
                        duk_uint_fast_t bc;
                        duk_tval *tv1, *tv2;

                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        bc = DUK_DEC_BC(ins); tv2 = DUK__REGP(bc);
                        DUK_TVAL_SET_TVAL_UPDREF_FAST(thr, tv1, tv2);  /* side effects */
                        break;
                }

                case DUK_OP_STREG: {
                        duk_small_uint_fast_t a;
                        duk_uint_fast_t bc;
                        duk_tval *tv1, *tv2;

                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        bc = DUK_DEC_BC(ins); tv2 = DUK__REGP(bc);
                        DUK_TVAL_SET_TVAL_UPDREF_FAST(thr, tv2, tv1);  /* side effects */
                        break;
                }

                case DUK_OP_LDCONST: {
                        duk_small_uint_fast_t a;
                        duk_uint_fast_t bc;
                        duk_tval *tv1, *tv2;

                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        bc = DUK_DEC_BC(ins); tv2 = DUK__CONSTP(bc);
                        DUK_TVAL_SET_TVAL_UPDREF_FAST(thr, tv1, tv2);  /* side effects */
                        break;
                }

                case DUK_OP_LDINT: {
                        duk_small_uint_fast_t a;
                        duk_int_fast_t bc;
                        duk_tval *tv1;
#if defined(DUK_USE_FASTINT)
                        duk_int32_t val;
#else
                        duk_double_t val;
#endif

#if defined(DUK_USE_FASTINT)
                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        bc = DUK_DEC_BC(ins); val = (duk_int32_t) (bc - DUK_BC_LDINT_BIAS);
                        DUK_TVAL_SET_FASTINT_I32_UPDREF(thr, tv1, val);  /* side effects */
#else
                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        bc = DUK_DEC_BC(ins); val = (duk_double_t) (bc - DUK_BC_LDINT_BIAS);
                        DUK_TVAL_SET_NUMBER_UPDREF(thr, tv1, val);  /* side effects */
#endif
                        break;
                }

                case DUK_OP_LDINTX: {
                        duk_small_uint_fast_t a;
                        duk_tval *tv1;
                        duk_double_t val;

                        /* LDINTX is not necessarily in FASTINT range, so
                         * no fast path for now.
                         *
                         * XXX: perhaps restrict LDINTX to fastint range, wider
                         * range very rarely needed.
                         */

                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv1));
                        val = DUK_TVAL_GET_NUMBER(tv1) * ((duk_double_t) (1L << DUK_BC_LDINTX_SHIFT)) +
                              (duk_double_t) DUK_DEC_BC(ins);
#if defined(DUK_USE_FASTINT)
                        DUK_TVAL_SET_NUMBER_CHKFAST(tv1, val);
#else
                        DUK_TVAL_SET_NUMBER(tv1, val);
#endif
                        break;
                }

                case DUK_OP_MPUTOBJ:
                case DUK_OP_MPUTOBJI: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a;
                        duk_tval *tv1;
                        duk_hobject *obj;
                        duk_uint_fast_t idx;
                        duk_small_uint_fast_t count;

                        /* A -> register of target object
                         * B -> first register of key/value pair list
                         * C -> number of key/value pairs
                         */

                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv1));
                        obj = DUK_TVAL_GET_OBJECT(tv1);

                        idx = (duk_uint_fast_t) DUK_DEC_B(ins);
                        if (DUK_DEC_OP(ins) == DUK_OP_MPUTOBJI) {
                                duk_tval *tv_ind = DUK__REGP(idx);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                        }

                        count = (duk_small_uint_fast_t) DUK_DEC_C(ins);

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                        if (DUK_UNLIKELY(idx + count * 2 > (duk_uint_fast_t) duk_get_top(ctx))) {
                                /* XXX: use duk_is_valid_index() instead? */
                                /* XXX: improve check; check against nregs, not against top */
                                DUK__INTERNAL_ERROR("MPUTOBJ out of bounds");
                        }
#endif

                        duk_push_hobject(ctx, obj);

                        while (count > 0) {
                                /* XXX: faster initialization (direct access or better primitives) */

                                duk_push_tval(ctx, DUK__REGP(idx));
                                DUK_ASSERT(duk_is_string(ctx, -1));
                                duk_push_tval(ctx, DUK__REGP(idx + 1));  /* -> [... obj key value] */
                                duk_xdef_prop_wec(ctx, -3);              /* -> [... obj] */

                                count--;
                                idx += 2;
                        }

                        duk_pop(ctx);  /* [... obj] -> [...] */
                        break;
                }

                case DUK_OP_MPUTARR:
                case DUK_OP_MPUTARRI: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a;
                        duk_tval *tv1;
                        duk_hobject *obj;
                        duk_uint_fast_t idx;
                        duk_small_uint_fast_t count;
                        duk_uint32_t arr_idx;

                        /* A -> register of target object
                         * B -> first register of value data (start_index, value1, value2, ..., valueN)
                         * C -> number of key/value pairs (N)
                         */

                        a = DUK_DEC_A(ins); tv1 = DUK__REGP(a);
                        DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv1));
                        obj = DUK_TVAL_GET_OBJECT(tv1);
                        DUK_ASSERT(obj != NULL);

                        idx = (duk_uint_fast_t) DUK_DEC_B(ins);
                        if (DUK_DEC_OP(ins) == DUK_OP_MPUTARRI) {
                                duk_tval *tv_ind = DUK__REGP(idx);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                        }

                        count = (duk_small_uint_fast_t) DUK_DEC_C(ins);

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                        if (idx + count + 1 > (duk_uint_fast_t) duk_get_top(ctx)) {
                                /* XXX: use duk_is_valid_index() instead? */
                                /* XXX: improve check; check against nregs, not against top */
                                DUK__INTERNAL_ERROR("MPUTARR out of bounds");
                        }
#endif

                        tv1 = DUK__REGP(idx);
                        DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv1));
                        arr_idx = (duk_uint32_t) DUK_TVAL_GET_NUMBER(tv1);
                        idx++;

                        duk_push_hobject(ctx, obj);

                        while (count > 0) {
                                /* duk_xdef_prop() will define an own property without any array
                                 * special behaviors.  We'll need to set the array length explicitly
                                 * in the end.  For arrays with elisions, the compiler will emit an
                                 * explicit SETALEN which will update the length.
                                 */

                                /* XXX: because we're dealing with 'own' properties of a fresh array,
                                 * the array initializer should just ensure that the array has a large
                                 * enough array part and write the values directly into array part,
                                 * and finally set 'length' manually in the end (as already happens now).
                                 */

                                duk_push_tval(ctx, DUK__REGP(idx));          /* -> [... obj value] */
                                duk_xdef_prop_index_wec(ctx, -2, arr_idx);   /* -> [... obj] */

                                /* XXX: could use at least one fewer loop counters */
                                count--;
                                idx++;
                                arr_idx++;
                        }

                        /* XXX: E5.1 Section 11.1.4 coerces the final length through
                         * ToUint32() which is odd but happens now as a side effect of
                         * 'arr_idx' type.
                         */
                        duk_hobject_set_length(thr, obj, (duk_uint32_t) arr_idx);

                        duk_pop(ctx);  /* [... obj] -> [...] */
                        break;
                }

                case DUK_OP_NEW:
                case DUK_OP_NEWI: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_uint_fast_t idx;
                        duk_small_uint_fast_t i;

                        /* A -> unused (reserved for flags, for consistency with DUK_OP_CALL)
                         * B -> target register and start reg: constructor, arg1, ..., argN
                         *      (for DUK_OP_NEWI, 'b' is indirect)
                         * C -> num args (N)
                         */

                        /* duk_new() will call the constuctor using duk_handle_call().
                         * A constructor call prevents a yield from inside the constructor,
                         * even if the constructor is an Ecmascript function.
                         */

                        /* Don't need to sync curr_pc here; duk_new() will do that
                         * when it augments the created error.
                         */

                        /* XXX: unnecessary copying of values?  Just set 'top' to
                         * b + c, and let the return handling fix up the stack frame?
                         */

                        idx = (duk_uint_fast_t) DUK_DEC_B(ins);
                        if (DUK_DEC_OP(ins) == DUK_OP_NEWI) {
                                duk_tval *tv_ind = DUK__REGP(idx);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                        }

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                        if (idx + c + 1 > (duk_uint_fast_t) duk_get_top(ctx)) {
                                /* XXX: use duk_is_valid_index() instead? */
                                /* XXX: improve check; check against nregs, not against top */
                                DUK__INTERNAL_ERROR("NEW out of bounds");
                        }
#endif

                        duk_require_stack(ctx, (duk_idx_t) c);
                        duk_push_tval(ctx, DUK__REGP(idx));
                        for (i = 0; i < c; i++) {
                                duk_push_tval(ctx, DUK__REGP(idx + i + 1));
                        }
                        duk_new(ctx, (duk_idx_t) c);  /* [... constructor arg1 ... argN] -> [retval] */
                        DUK_DDD(DUK_DDDPRINT("NEW -> %!iT", (duk_tval *) duk_get_tval(ctx, -1)));
                        duk_replace(ctx, (duk_idx_t) idx);

                        /* When debugger is enabled, we need to recheck the activation
                         * status after returning.  This is now handled by call handling
                         * and heap->dbg_force_restart.
                         */
                        break;
                }

                case DUK_OP_REGEXP: {
#ifdef DUK_USE_REGEXP_SUPPORT
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);

                        /* A -> target register
                         * B -> bytecode (also contains flags)
                         * C -> escaped source
                         */

                        duk_push_tval(ctx, DUK__REGCONSTP(c));
                        duk_push_tval(ctx, DUK__REGCONSTP(b));  /* -> [ ... escaped_source bytecode ] */
                        duk_regexp_create_instance(thr);   /* -> [ ... regexp_instance ] */
                        DUK_DDD(DUK_DDDPRINT("regexp instance: %!iT", (duk_tval *) duk_get_tval(ctx, -1)));
                        duk_replace(ctx, (duk_idx_t) a);
#else
                        /* The compiler should never emit DUK_OP_REGEXP if there is no
                         * regexp support.
                         */
                        DUK__INTERNAL_ERROR("no regexp support");
#endif

                        break;
                }

                case DUK_OP_CSREG:
                case DUK_OP_CSREGI: {
                        /*
                         *  Assuming a register binds to a variable declared within this
                         *  function (a declarative binding), the 'this' for the call
                         *  setup is always 'undefined'.  E5 Section 10.2.1.1.6.
                         */

                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);  /* restricted to regs */
                        duk_uint_fast_t idx;

                        /* A -> target register (A, A+1) for call setup
                         *      (for DUK_OP_CSREGI, 'a' is indirect)
                         * B -> register containing target function (not type checked here)
                         */

                        /* XXX: direct manipulation, or duk_replace_tval() */

                        /* Note: target registers a and a+1 may overlap with DUK__REGP(b).
                         * Careful here.
                         */

                        idx = (duk_uint_fast_t) DUK_DEC_A(ins);
                        if (DUK_DEC_OP(ins) == DUK_OP_CSREGI) {
                                duk_tval *tv_ind = DUK__REGP(idx);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                        }

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                        if (idx + 2 > (duk_uint_fast_t) duk_get_top(ctx)) {
                                /* XXX: use duk_is_valid_index() instead? */
                                /* XXX: improve check; check against nregs, not against top */
                                DUK__INTERNAL_ERROR("CSREG out of bounds");
                        }
#endif

                        duk_push_tval(ctx, DUK__REGP(b));
                        duk_replace(ctx, (duk_idx_t) idx);
                        duk_push_undefined(ctx);
                        duk_replace(ctx, (duk_idx_t) (idx + 1));
                        break;
                }

                case DUK_OP_GETVAR: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_activation *act;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_uint_fast_t bc = DUK_DEC_BC(ins);
                        duk_tval *tv1;
                        duk_hstring *name;

                        tv1 = DUK__CONSTP(bc);
                        DUK_ASSERT(DUK_TVAL_IS_STRING(tv1));
                        name = DUK_TVAL_GET_STRING(tv1);
                        DUK_ASSERT(name != NULL);
                        DUK_DDD(DUK_DDDPRINT("GETVAR: '%!O'", (duk_heaphdr *) name));
                        act = thr->callstack + thr->callstack_top - 1;
                        (void) duk_js_getvar_activation(thr, act, name, 1 /*throw*/);  /* -> [... val this] */

                        duk_pop(ctx);  /* 'this' binding is not needed here */
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_PUTVAR: {
                        duk_activation *act;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_uint_fast_t bc = DUK_DEC_BC(ins);
                        duk_tval *tv1;
                        duk_hstring *name;

                        tv1 = DUK__CONSTP(bc);
                        DUK_ASSERT(DUK_TVAL_IS_STRING(tv1));
                        name = DUK_TVAL_GET_STRING(tv1);
                        DUK_ASSERT(name != NULL);

                        /* XXX: putvar takes a duk_tval pointer, which is awkward and
                         * should be reworked.
                         */

                        tv1 = DUK__REGP(a);  /* val */
                        act = thr->callstack + thr->callstack_top - 1;
                        duk_js_putvar_activation(thr, act, name, tv1, DUK__STRICT());
                        break;
                }

                case DUK_OP_DECLVAR: {
                        duk_activation *act;
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_tval *tv1;
                        duk_hstring *name;
                        duk_small_uint_t prop_flags;
                        duk_bool_t is_func_decl;
                        duk_bool_t is_undef_value;

                        tv1 = DUK__REGCONSTP(b);
                        DUK_ASSERT(DUK_TVAL_IS_STRING(tv1));
                        name = DUK_TVAL_GET_STRING(tv1);
                        DUK_ASSERT(name != NULL);

                        is_undef_value = ((a & DUK_BC_DECLVAR_FLAG_UNDEF_VALUE) != 0);
                        is_func_decl = ((a & DUK_BC_DECLVAR_FLAG_FUNC_DECL) != 0);

                        /* XXX: declvar takes an duk_tval pointer, which is awkward and
                         * should be reworked.
                         */

                        /* Compiler is responsible for selecting property flags (configurability,
                         * writability, etc).
                         */
                        prop_flags = a & DUK_PROPDESC_FLAGS_MASK;

                        if (is_undef_value) {
                                duk_push_undefined(ctx);
                        } else {
                                duk_push_tval(ctx, DUK__REGCONSTP(c));
                        }
                        tv1 = DUK_GET_TVAL_NEGIDX(ctx, -1);

                        act = thr->callstack + thr->callstack_top - 1;
                        if (duk_js_declvar_activation(thr, act, name, tv1, prop_flags, is_func_decl)) {
                                /* already declared, must update binding value */
                                tv1 = DUK_GET_TVAL_NEGIDX(ctx, -1);
                                duk_js_putvar_activation(thr, act, name, tv1, DUK__STRICT());
                        }

                        duk_pop(ctx);
                        break;
                }

                case DUK_OP_DELVAR: {
                        duk_activation *act;
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_tval *tv1;
                        duk_hstring *name;
                        duk_bool_t rc;

                        tv1 = DUK__REGCONSTP(b);
                        DUK_ASSERT(DUK_TVAL_IS_STRING(tv1));
                        name = DUK_TVAL_GET_STRING(tv1);
                        DUK_ASSERT(name != NULL);
                        DUK_DDD(DUK_DDDPRINT("DELVAR '%!O'", (duk_heaphdr *) name));
                        act = thr->callstack + thr->callstack_top - 1;
                        rc = duk_js_delvar_activation(thr, act, name);

                        duk_push_boolean(ctx, rc);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_CSVAR:
                case DUK_OP_CSVARI: {
                        /* 'this' value:
                         * E5 Section 6.b.i
                         *
                         * The only (standard) case where the 'this' binding is non-null is when
                         *   (1) the variable is found in an object environment record, and
                         *   (2) that object environment record is a 'with' block.
                         *
                         */

                        duk_context *ctx = (duk_context *) thr;
                        duk_activation *act;
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_uint_fast_t idx;
                        duk_tval *tv1;
                        duk_hstring *name;

                        tv1 = DUK__REGCONSTP(b);
                        DUK_ASSERT(DUK_TVAL_IS_STRING(tv1));
                        name = DUK_TVAL_GET_STRING(tv1);
                        DUK_ASSERT(name != NULL);
                        act = thr->callstack + thr->callstack_top - 1;
                        (void) duk_js_getvar_activation(thr, act, name, 1 /*throw*/);  /* -> [... val this] */

                        /* Note: target registers a and a+1 may overlap with DUK__REGCONSTP(b)
                         * and DUK__REGCONSTP(c).  Careful here.
                         */

                        idx = (duk_uint_fast_t) DUK_DEC_A(ins);
                        if (DUK_DEC_OP(ins) == DUK_OP_CSVARI) {
                                duk_tval *tv_ind = DUK__REGP(idx);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                        }

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                        if (idx + 2 > (duk_uint_fast_t) duk_get_top(ctx)) {
                                /* XXX: use duk_is_valid_index() instead? */
                                /* XXX: improve check; check against nregs, not against top */
                                DUK__INTERNAL_ERROR("CSVAR out of bounds");
                        }
#endif

                        duk_replace(ctx, (duk_idx_t) (idx + 1));  /* 'this' binding */
                        duk_replace(ctx, (duk_idx_t) idx);        /* variable value (function, we hope, not checked here) */
                        break;
                }

                case DUK_OP_CLOSURE: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_activation *act;
                        duk_hcompiledfunction *fun;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_uint_fast_t bc = DUK_DEC_BC(ins);
                        duk_hobject *fun_temp;

                        /* A -> target reg
                         * BC -> inner function index
                         */

                        DUK_DDD(DUK_DDDPRINT("CLOSURE to target register %ld, fnum %ld (count %ld)",
                                             (long) a, (long) bc, (long) DUK_HCOMPILEDFUNCTION_GET_FUNCS_COUNT(thr->heap, DUK__FUN())));

                        DUK_ASSERT_DISABLE(bc >= 0); /* unsigned */
                        DUK_ASSERT((duk_uint_t) bc < (duk_uint_t) DUK_HCOMPILEDFUNCTION_GET_FUNCS_COUNT(thr->heap, DUK__FUN()));

                        act = thr->callstack + thr->callstack_top - 1;
                        fun = (duk_hcompiledfunction *) DUK_ACT_GET_FUNC(act);
                        fun_temp = DUK_HCOMPILEDFUNCTION_GET_FUNCS_BASE(thr->heap, fun)[bc];
                        DUK_ASSERT(fun_temp != NULL);
                        DUK_ASSERT(DUK_HOBJECT_IS_COMPILEDFUNCTION(fun_temp));

                        DUK_DDD(DUK_DDDPRINT("CLOSURE: function template is: %p -> %!O",
                                             (void *) fun_temp, (duk_heaphdr *) fun_temp));

                        if (act->lex_env == NULL) {
                                DUK_ASSERT(act->var_env == NULL);
                                duk_js_init_activation_environment_records_delayed(thr, act);
                        }
                        DUK_ASSERT(act->lex_env != NULL);
                        DUK_ASSERT(act->var_env != NULL);

                        /* functions always have a NEWENV flag, i.e. they get a
                         * new variable declaration environment, so only lex_env
                         * matters here.
                         */
                        duk_js_push_closure(thr,
                                            (duk_hcompiledfunction *) fun_temp,
                                            act->var_env,
                                            act->lex_env,
                                            1 /*add_auto_proto*/);
                        duk_replace(ctx, (duk_idx_t) a);

                        break;
                }

                case DUK_OP_GETPROP: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_tval *tv_obj;
                        duk_tval *tv_key;
                        duk_bool_t rc;

                        /* A -> target reg
                         * B -> object reg/const (may be const e.g. in "'foo'[1]")
                         * C -> key reg/const
                         */

                        tv_obj = DUK__REGCONSTP(b);
                        tv_key = DUK__REGCONSTP(c);
                        DUK_DDD(DUK_DDDPRINT("GETPROP: a=%ld obj=%!T, key=%!T",
                                             (long) a,
                                             (duk_tval *) DUK__REGCONSTP(b),
                                             (duk_tval *) DUK__REGCONSTP(c)));
                        rc = duk_hobject_getprop(thr, tv_obj, tv_key);  /* -> [val] */
                        DUK_UNREF(rc);  /* ignore */
                        DUK_DDD(DUK_DDDPRINT("GETPROP --> %!T",
                                             (duk_tval *) duk_get_tval(ctx, -1)));
                        tv_obj = NULL;  /* invalidated */
                        tv_key = NULL;  /* invalidated */

                        duk_replace(ctx, (duk_idx_t) a);    /* val */
                        break;
                }

                case DUK_OP_PUTPROP: {
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_tval *tv_obj;
                        duk_tval *tv_key;
                        duk_tval *tv_val;
                        duk_bool_t rc;

                        /* A -> object reg
                         * B -> key reg/const
                         * C -> value reg/const
                         *
                         * Note: intentional difference to register arrangement
                         * of e.g. GETPROP; 'A' must contain a register-only value.
                         */

                        tv_obj = DUK__REGP(a);
                        tv_key = DUK__REGCONSTP(b);
                        tv_val = DUK__REGCONSTP(c);
                        DUK_DDD(DUK_DDDPRINT("PUTPROP: obj=%!T, key=%!T, val=%!T",
                                             (duk_tval *) DUK__REGP(a),
                                             (duk_tval *) DUK__REGCONSTP(b),
                                             (duk_tval *) DUK__REGCONSTP(c)));
                        rc = duk_hobject_putprop(thr, tv_obj, tv_key, tv_val, DUK__STRICT());
                        DUK_UNREF(rc);  /* ignore */
                        DUK_DDD(DUK_DDDPRINT("PUTPROP --> obj=%!T, key=%!T, val=%!T",
                                             (duk_tval *) DUK__REGP(a),
                                             (duk_tval *) DUK__REGCONSTP(b),
                                             (duk_tval *) DUK__REGCONSTP(c)));
                        tv_obj = NULL;  /* invalidated */
                        tv_key = NULL;  /* invalidated */
                        tv_val = NULL;  /* invalidated */

                        break;
                }

                case DUK_OP_DELPROP: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_tval *tv_obj;
                        duk_tval *tv_key;
                        duk_bool_t rc;

                        /* A -> result reg
                         * B -> object reg
                         * C -> key reg/const
                         */

                        tv_obj = DUK__REGP(b);
                        tv_key = DUK__REGCONSTP(c);
                        rc = duk_hobject_delprop(thr, tv_obj, tv_key, DUK__STRICT());
                        tv_obj = NULL;  /* invalidated */
                        tv_key = NULL;  /* invalidated */

                        duk_push_boolean(ctx, rc);
                        duk_replace(ctx, (duk_idx_t) a);    /* result */
                        break;
                }

                case DUK_OP_CSPROP:
                case DUK_OP_CSPROPI: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_uint_fast_t idx;
                        duk_tval *tv_obj;
                        duk_tval *tv_key;
                        duk_bool_t rc;

                        /* E5 Section 11.2.3, step 6.a.i */
                        /* E5 Section 10.4.3 */

                        /* XXX: allow object to be a const, e.g. in 'foo'.toString()?
                         * On the other hand, DUK_REGCONSTP() is slower and generates
                         * more code.
                         */

                        tv_obj = DUK__REGP(b);
                        tv_key = DUK__REGCONSTP(c);
                        rc = duk_hobject_getprop(thr, tv_obj, tv_key);  /* -> [val] */
                        DUK_UNREF(rc);  /* unused */
                        tv_obj = NULL;  /* invalidated */
                        tv_key = NULL;  /* invalidated */

                        /* Note: target registers a and a+1 may overlap with DUK__REGP(b)
                         * and DUK__REGCONSTP(c).  Careful here.
                         */

                        idx = (duk_uint_fast_t) DUK_DEC_A(ins);
                        if (DUK_DEC_OP(ins) == DUK_OP_CSPROPI) {
                                duk_tval *tv_ind = DUK__REGP(idx);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                        }

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                        if (idx + 2 > (duk_uint_fast_t) duk_get_top(ctx)) {
                                /* XXX: use duk_is_valid_index() instead? */
                                /* XXX: improve check; check against nregs, not against top */
                                DUK__INTERNAL_ERROR("CSPROP out of bounds");
                        }
#endif

                        duk_push_tval(ctx, DUK__REGP(b));         /* [ ... val obj ] */
                        duk_replace(ctx, (duk_idx_t) (idx + 1));  /* 'this' binding */
                        duk_replace(ctx, (duk_idx_t) idx);        /* val */
                        break;
                }

                case DUK_OP_ADD:
                case DUK_OP_SUB:
                case DUK_OP_MUL:
                case DUK_OP_DIV:
                case DUK_OP_MOD: {
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_small_uint_fast_t op = DUK_DEC_OP(ins);

                        if (op == DUK_OP_ADD) {
                                /*
                                 *  Handling DUK_OP_ADD this way is more compact (experimentally)
                                 *  than a separate case with separate argument decoding.
                                 */
                                duk__vm_arith_add(thr, DUK__REGCONSTP(b), DUK__REGCONSTP(c), a);
                        } else {
                                duk__vm_arith_binary_op(thr, DUK__REGCONSTP(b), DUK__REGCONSTP(c), a, op);
                        }
                        break;
                }

                case DUK_OP_BAND:
                case DUK_OP_BOR:
                case DUK_OP_BXOR:
                case DUK_OP_BASL:
                case DUK_OP_BLSR:
                case DUK_OP_BASR: {
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_small_uint_fast_t op = DUK_DEC_OP(ins);

                        duk__vm_bitwise_binary_op(thr, DUK__REGCONSTP(b), DUK__REGCONSTP(c), a, op);
                        break;
                }

                case DUK_OP_EQ:
                case DUK_OP_NEQ: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_bool_t tmp;

                        /* E5 Sections 11.9.1, 11.9.3 */
                        tmp = duk_js_equals(thr, DUK__REGCONSTP(b), DUK__REGCONSTP(c));
                        if (DUK_DEC_OP(ins) == DUK_OP_NEQ) {
                                tmp = !tmp;
                        }
                        duk_push_boolean(ctx, tmp);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_SEQ:
                case DUK_OP_SNEQ: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_bool_t tmp;

                        /* E5 Sections 11.9.1, 11.9.3 */
                        tmp = duk_js_strict_equals(DUK__REGCONSTP(b), DUK__REGCONSTP(c));
                        if (DUK_DEC_OP(ins) == DUK_OP_SNEQ) {
                                tmp = !tmp;
                        }
                        duk_push_boolean(ctx, tmp);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                /* Note: combining comparison ops must be done carefully because
                 * of uncomparable values (NaN): it's not necessarily true that
                 * (x >= y) === !(x < y).  Also, evaluation order matters, and
                 * although it would only seem to affect the compiler this is
                 * actually not the case, because there are also run-time coercions
                 * of the arguments (with potential side effects).
                 *
                 * XXX: can be combined; check code size.
                 */

                case DUK_OP_GT: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_bool_t tmp;

                        /* x > y  -->  y < x */
                        tmp = duk_js_compare_helper(thr,
                                                    DUK__REGCONSTP(c),  /* y */
                                                    DUK__REGCONSTP(b),  /* x */
                                                    0);                 /* flags */

                        duk_push_boolean(ctx, tmp);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_GE: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_bool_t tmp;

                        /* x >= y  -->  not (x < y) */
                        tmp = duk_js_compare_helper(thr,
                                                    DUK__REGCONSTP(b),  /* x */
                                                    DUK__REGCONSTP(c),  /* y */
                                                    DUK_COMPARE_FLAG_EVAL_LEFT_FIRST |
                                                    DUK_COMPARE_FLAG_NEGATE);  /* flags */

                        duk_push_boolean(ctx, tmp);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_LT: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_bool_t tmp;

                        /* x < y */
                        tmp = duk_js_compare_helper(thr,
                                                    DUK__REGCONSTP(b),  /* x */
                                                    DUK__REGCONSTP(c),  /* y */
                                                    DUK_COMPARE_FLAG_EVAL_LEFT_FIRST);  /* flags */

                        duk_push_boolean(ctx, tmp);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_LE: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_bool_t tmp;

                        /* x <= y  -->  not (x > y)  -->  not (y < x) */
                        tmp = duk_js_compare_helper(thr,
                                                    DUK__REGCONSTP(c),  /* y */
                                                    DUK__REGCONSTP(b),  /* x */
                                                    DUK_COMPARE_FLAG_NEGATE);  /* flags */

                        duk_push_boolean(ctx, tmp);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_IF: {
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_bool_t tmp;

                        tmp = duk_js_toboolean(DUK__REGCONSTP(b));
                        if (tmp == (duk_bool_t) a) {
                                /* if boolean matches A, skip next inst */
                                curr_pc++;
                        } else {
                                ;
                        }
                        break;
                }

                case DUK_OP_JUMP: {
                        duk_int_fast_t abc = DUK_DEC_ABC(ins);

                        curr_pc += abc - DUK_BC_JUMP_BIAS;
                        break;
                }

                case DUK_OP_RETURN: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        /* duk_small_uint_fast_t c = DUK_DEC_C(ins); */
                        duk_small_uint_t ret_result;

                        /* A -> flags
                         * B -> return value reg/const
                         * C -> currently unused
                         */

                        DUK__SYNC_AND_NULL_CURR_PC();

                        /* duk__handle_return() is guaranteed never to throw, except
                         * for potential out-of-memory situations which will then
                         * propagate out of the executor longjmp handler.
                         */

                        if (a & DUK_BC_RETURN_FLAG_HAVE_RETVAL) {
                                duk_push_tval(ctx, DUK__REGCONSTP(b));
                        } else {
                                duk_push_undefined(ctx);
                        }
                        ret_result = duk__handle_return(thr,
                                                        entry_thread,
                                                        entry_callstack_top);
                        if (ret_result == DUK__RETHAND_RESTART) {
                                goto restart_execution;
                        }
                        DUK_ASSERT(ret_result == DUK__RETHAND_FINISHED);

                        DUK_DDD(DUK_DDDPRINT("exiting executor after RETURN handling"));
                        return;
                }

                case DUK_OP_CALL:
                case DUK_OP_CALLI: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_uint_fast_t idx;
                        duk_small_uint_t call_flags;
                        duk_small_uint_t flag_tailcall;
                        duk_small_uint_t flag_evalcall;
                        duk_tval *tv_func;
                        duk_hobject *obj_func;
                        duk_bool_t setup_rc;
                        duk_idx_t num_stack_args;
#if !defined(DUK_USE_EXEC_FUN_LOCAL)
                        duk_hcompiledfunction *fun;
#endif

                        /* A -> flags
                         * B -> base register for call (base -> func, base+1 -> this, base+2 -> arg1 ... base+2+N-1 -> argN)
                         *      (for DUK_OP_CALLI, 'b' is indirect)
                         * C -> nargs
                         */

                        /* these are not necessarily 0 or 1 (may be other non-zero), that's ok */
                        flag_tailcall = (a & DUK_BC_CALL_FLAG_TAILCALL);
                        flag_evalcall = (a & DUK_BC_CALL_FLAG_EVALCALL);

                        idx = (duk_uint_fast_t) DUK_DEC_B(ins);
                        if (DUK_DEC_OP(ins) == DUK_OP_CALLI) {
                                duk_tval *tv_ind = DUK__REGP(idx);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                        }

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                        if (!duk_is_valid_index(ctx, (duk_idx_t) idx)) {
                                /* XXX: improve check; check against nregs, not against top */
                                DUK__INTERNAL_ERROR("CALL out of bounds");
                        }
#endif

                        /*
                         *  To determine whether to use an optimized Ecmascript-to-Ecmascript
                         *  call, we need to know whether the final, non-bound function is an
                         *  Ecmascript function.
                         *
                         *  This is now implemented so that we start to do an ecma-to-ecma call
                         *  setup which will resolve the bound chain as the first thing.  If the
                         *  final function is not eligible, the return value indicates that the
                         *  ecma-to-ecma call is not possible.  The setup will overwrite the call
                         *  target at DUK__REGP(idx) with the final, non-bound function (which
                         *  may be a lightfunc), and fudge arguments if necessary.
                         *
                         *  XXX: If an ecma-to-ecma call is not possible, this initial call
                         *  setup will do bound function chain resolution but won't do the
                         *  "effective this binding" resolution which is quite confusing.
                         *  Perhaps add a helper for doing bound function and effective this
                         *  binding resolution - and call that explicitly?  Ecma-to-ecma call
                         *  setup and normal function handling can then assume this prestep has
                         *  been done by the caller.
                         */

                        duk_set_top(ctx, (duk_idx_t) (idx + c + 2));   /* [ ... func this arg1 ... argN ] */

                        call_flags = 0;
                        if (flag_tailcall) {
                                /* We request a tail call, but in some corner cases
                                 * call handling can decide that a tail call is
                                 * actually not possible.
                                 * See: test-bug-tailcall-preventyield-assert.c.
                                 */
                                call_flags |= DUK_CALL_FLAG_IS_TAILCALL;
                        }

                        /* Compared to duk_handle_call():
                         *   - protected call: never
                         *   - ignore recursion limit: never
                         */
                        num_stack_args = c;
                        setup_rc = duk_handle_ecma_call_setup(thr,
                                                              num_stack_args,
                                                              call_flags);

                        if (setup_rc) {
                                /* Ecma-to-ecma call possible, may or may not be a tail call.
                                 * Avoid C recursion by being clever.
                                 */
                                DUK_DDD(DUK_DDDPRINT("ecma-to-ecma call setup possible, restart execution"));
                                /* curr_pc synced by duk_handle_ecma_call_setup() */
                                goto restart_execution;
                        }
                        DUK_ASSERT(thr->ptr_curr_pc != NULL);  /* restored if ecma-to-ecma setup fails */

                        DUK_DDD(DUK_DDDPRINT("ecma-to-ecma call not possible, target is native (may be lightfunc)"));

                        /* Recompute argument count: bound function handling may have shifted. */
                        num_stack_args = duk_get_top(ctx) - (idx + 2);
                        DUK_DDD(DUK_DDDPRINT("recomputed arg count: %ld\n", (long) num_stack_args));

                        tv_func = DUK__REGP(idx);  /* Relookup if relocated */
                        if (DUK_TVAL_IS_LIGHTFUNC(tv_func)) {

                                call_flags = 0;  /* not protected, respect reclimit, not constructor */

                                /* There is no eval() special handling here: eval() is never
                                 * automatically converted to a lightfunc.
                                 */
                                DUK_ASSERT(DUK_TVAL_GET_LIGHTFUNC_FUNCPTR(tv_func) != duk_bi_global_object_eval);

                                duk_handle_call_unprotected(thr,
                                                            num_stack_args,
                                                            call_flags);

                                /* duk_js_call.c is required to restore the stack reserve
                                 * so we only need to reset the top.
                                 */
#if !defined(DUK_USE_EXEC_FUN_LOCAL)
                                fun = DUK__FUN();
#endif
                                duk_set_top(ctx, (duk_idx_t) fun->nregs);

                                /* No need to reinit setjmp() catchpoint, as call handling
                                 * will store and restore our state.
                                 */
                        } else {
                                /* Call setup checks callability. */
                                DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv_func));
                                obj_func = DUK_TVAL_GET_OBJECT(tv_func);
                                DUK_ASSERT(obj_func != NULL);
                                DUK_ASSERT(!DUK_HOBJECT_HAS_BOUND(obj_func));

                                /*
                                 *  Other cases, use C recursion.
                                 *
                                 *  If a tail call was requested we ignore it and execute a normal call.
                                 *  Since Duktape 0.11.0 the compiler emits a RETURN opcode even after
                                 *  a tail call to avoid test-bug-tailcall-thread-yield-resume.js.
                                 *
                                 *  Direct eval call: (1) call target (before following bound function
                                 *  chain) is the built-in eval() function, and (2) call was made with
                                 *  the identifier 'eval'.
                                 */

                                call_flags = 0;  /* not protected, respect reclimit, not constructor */

                                if (DUK_HOBJECT_IS_NATIVEFUNCTION(obj_func) &&
                                    ((duk_hnativefunction *) obj_func)->func == duk_bi_global_object_eval) {
                                        if (flag_evalcall) {
                                                DUK_DDD(DUK_DDDPRINT("call target is eval, call identifier was 'eval' -> direct eval"));
                                                call_flags |= DUK_CALL_FLAG_DIRECT_EVAL;
                                        } else {
                                                DUK_DDD(DUK_DDDPRINT("call target is eval, call identifier was not 'eval' -> indirect eval"));
                                        }
                                }

                                duk_handle_call_unprotected(thr,
                                                            num_stack_args,
                                                            call_flags);

                                /* duk_js_call.c is required to restore the stack reserve
                                 * so we only need to reset the top.
                                 */
#if !defined(DUK_USE_EXEC_FUN_LOCAL)
                                fun = DUK__FUN();
#endif
                                duk_set_top(ctx, (duk_idx_t) fun->nregs);

                                /* No need to reinit setjmp() catchpoint, as call handling
                                 * will store and restore our state.
                                 */
                        }

                        /* When debugger is enabled, we need to recheck the activation
                         * status after returning.  This is now handled by call handling
                         * and heap->dbg_force_restart.
                         */
                        break;
                }

                case DUK_OP_TRYCATCH: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_activation *act;
                        duk_catcher *cat;
                        duk_tval *tv1;
                        duk_small_uint_fast_t a;
                        duk_uint_fast_t bc;

                        /* A -> flags
                         * BC -> reg_catch; base register for two registers used both during
                         *       trycatch setup and when catch is triggered
                         *
                         *      If DUK_BC_TRYCATCH_FLAG_CATCH_BINDING set:
                         *          reg_catch + 0: catch binding variable name (string).
                         *          Automatic declarative environment is established for
                         *          the duration of the 'catch' clause.
                         *
                         *      If DUK_BC_TRYCATCH_FLAG_WITH_BINDING set:
                         *          reg_catch + 0: with 'target value', which is coerced to
                         *          an object and then used as a bindind object for an
                         *          environment record.  The binding is initialized here, for
                         *          the 'try' clause.
                         *
                         * Note that a TRYCATCH generated for a 'with' statement has no
                         * catch or finally parts.
                         */

                        /* XXX: TRYCATCH handling should be reworked to avoid creating
                         * an explicit scope unless it is actually needed (e.g. function
                         * instances or eval is executed inside the catch block).  This
                         * rework is not trivial because the compiler doesn't have an
                         * intermediate representation.  When the rework is done, the
                         * opcode format can also be made more straightforward.
                         */

                        /* XXX: side effect handling is quite awkward here */

                        DUK_DDD(DUK_DDDPRINT("TRYCATCH: reg_catch=%ld, have_catch=%ld, "
                                             "have_finally=%ld, catch_binding=%ld, with_binding=%ld (flags=0x%02lx)",
                                             (long) DUK_DEC_BC(ins),
                                             (long) (DUK_DEC_A(ins) & DUK_BC_TRYCATCH_FLAG_HAVE_CATCH ? 1 : 0),
                                             (long) (DUK_DEC_A(ins) & DUK_BC_TRYCATCH_FLAG_HAVE_FINALLY ? 1 : 0),
                                             (long) (DUK_DEC_A(ins) & DUK_BC_TRYCATCH_FLAG_CATCH_BINDING ? 1 : 0),
                                             (long) (DUK_DEC_A(ins) & DUK_BC_TRYCATCH_FLAG_WITH_BINDING ? 1 : 0),
                                             (unsigned long) DUK_DEC_A(ins)));

                        a = DUK_DEC_A(ins);
                        bc = DUK_DEC_BC(ins);

                        act = thr->callstack + thr->callstack_top - 1;
                        DUK_ASSERT(thr->callstack_top >= 1);

                        /* 'with' target must be created first, in case we run out of memory */
                        /* XXX: refactor out? */

                        if (a & DUK_BC_TRYCATCH_FLAG_WITH_BINDING) {
                                DUK_DDD(DUK_DDDPRINT("need to initialize a with binding object"));

                                if (act->lex_env == NULL) {
                                        DUK_ASSERT(act->var_env == NULL);
                                        DUK_DDD(DUK_DDDPRINT("delayed environment initialization"));

                                        /* must relookup act in case of side effects */
                                        duk_js_init_activation_environment_records_delayed(thr, act);
                                        act = thr->callstack + thr->callstack_top - 1;
                                        DUK_UNREF(act);  /* 'act' is no longer accessed, scanbuild fix */
                                }
                                DUK_ASSERT(act->lex_env != NULL);
                                DUK_ASSERT(act->var_env != NULL);

                                (void) duk_push_object_helper(ctx,
                                                              DUK_HOBJECT_FLAG_EXTENSIBLE |
                                                              DUK_HOBJECT_CLASS_AS_FLAGS(DUK_HOBJECT_CLASS_OBJENV),
                                                              -1);  /* no prototype, updated below */

                                duk_push_tval(ctx, DUK__REGP(bc));
                                duk_to_object(ctx, -1);
                                duk_dup(ctx, -1);

                                /* [ ... env target ] */
                                /* [ ... env target target ] */

                                duk_xdef_prop_stridx(thr, -3, DUK_STRIDX_INT_TARGET, DUK_PROPDESC_FLAGS_NONE);
                                duk_xdef_prop_stridx(thr, -2, DUK_STRIDX_INT_THIS, DUK_PROPDESC_FLAGS_NONE);  /* always provideThis=true */

                                /* [ ... env ] */

                                DUK_DDD(DUK_DDDPRINT("environment for with binding: %!iT",
                                                     (duk_tval *) duk_get_tval(ctx, -1)));
                        }

                        /* allocate catcher and populate it (should be atomic) */

                        duk_hthread_catchstack_grow(thr);
                        cat = thr->catchstack + thr->catchstack_top;
                        DUK_ASSERT(thr->catchstack_top + 1 <= thr->catchstack_size);
                        thr->catchstack_top++;

                        cat->flags = DUK_CAT_TYPE_TCF;
                        cat->h_varname = NULL;

                        if (a & DUK_BC_TRYCATCH_FLAG_HAVE_CATCH) {
                                cat->flags |= DUK_CAT_FLAG_CATCH_ENABLED;
                        }
                        if (a & DUK_BC_TRYCATCH_FLAG_HAVE_FINALLY) {
                                cat->flags |= DUK_CAT_FLAG_FINALLY_ENABLED;
                        }
                        if (a & DUK_BC_TRYCATCH_FLAG_CATCH_BINDING) {
                                DUK_DDD(DUK_DDDPRINT("catch binding flag set to catcher"));
                                cat->flags |= DUK_CAT_FLAG_CATCH_BINDING_ENABLED;
                                tv1 = DUK__REGP(bc);
                                DUK_ASSERT(DUK_TVAL_IS_STRING(tv1));

                                /* borrowed reference; although 'tv1' comes from a register,
                                 * its value was loaded using LDCONST so the constant will
                                 * also exist and be reachable.
                                 */
                                cat->h_varname = DUK_TVAL_GET_STRING(tv1);
                        } else if (a & DUK_BC_TRYCATCH_FLAG_WITH_BINDING) {
                                /* env created above to stack top */
                                duk_hobject *new_env;

                                DUK_DDD(DUK_DDDPRINT("lexenv active flag set to catcher"));
                                cat->flags |= DUK_CAT_FLAG_LEXENV_ACTIVE;

                                DUK_DDD(DUK_DDDPRINT("activating object env: %!iT",
                                                     (duk_tval *) duk_get_tval(ctx, -1)));
                                DUK_ASSERT(act->lex_env != NULL);
                                new_env = DUK_GET_HOBJECT_NEGIDX(ctx, -1);
                                DUK_ASSERT(new_env != NULL);

                                act = thr->callstack + thr->callstack_top - 1;  /* relookup (side effects) */
                                DUK_HOBJECT_SET_PROTOTYPE_UPDREF(thr, new_env, act->lex_env);  /* side effects */

                                act = thr->callstack + thr->callstack_top - 1;  /* relookup (side effects) */
                                act->lex_env = new_env;
                                DUK_HOBJECT_INCREF(thr, new_env);
                                duk_pop(ctx);
                        } else {
                                ;
                        }

                        /* Registers 'bc' and 'bc + 1' are written in longjmp handling
                         * and if their previous values (which are temporaries) become
                         * unreachable -and- have a finalizer, there'll be a function
                         * call during error handling which is not supported now (GH-287).
                         * Ensure that both 'bc' and 'bc + 1' have primitive values to
                         * guarantee no finalizer calls in error handling.  Scrubbing also
                         * ensures finalizers for the previous values run here rather than
                         * later.  Error handling related values are also written to 'bc'
                         * and 'bc + 1' but those values never become unreachable during
                         * error handling, so there's no side effect problem even if the
                         * error value has a finalizer.
                         */
                        duk_to_undefined(ctx, bc);
                        duk_to_undefined(ctx, bc + 1);

                        cat = thr->catchstack + thr->catchstack_top - 1;  /* relookup (side effects) */
                        cat->callstack_index = thr->callstack_top - 1;
                        cat->pc_base = (duk_instr_t *) curr_pc;  /* pre-incremented, points to first jump slot */
                        cat->idx_base = (duk_size_t) (thr->valstack_bottom - thr->valstack) + bc;

                        DUK_DDD(DUK_DDDPRINT("TRYCATCH catcher: flags=0x%08lx, callstack_index=%ld, pc_base=%ld, "
                                             "idx_base=%ld, h_varname=%!O",
                                             (unsigned long) cat->flags, (long) cat->callstack_index,
                                             (long) cat->pc_base, (long) cat->idx_base, (duk_heaphdr *) cat->h_varname));

                        curr_pc += 2;  /* skip jump slots */
                        break;
                }

                /* Pre/post inc/dec for register variables, important for loops. */
                case DUK_OP_PREINCR:
                case DUK_OP_PREDECR:
                case DUK_OP_POSTINCR:
                case DUK_OP_POSTDECR: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_uint_fast_t bc = DUK_DEC_BC(ins);
                        duk_tval *tv1, *tv2;
                        duk_double_t x, y, z;

                        /* Two lowest bits of opcode are used to distinguish
                         * variants.  Bit 0 = inc(0)/dec(1), bit 1 = pre(0)/post(1).
                         */
                        DUK_ASSERT((DUK_OP_PREINCR & 0x03) == 0x00);
                        DUK_ASSERT((DUK_OP_PREDECR & 0x03) == 0x01);
                        DUK_ASSERT((DUK_OP_POSTINCR & 0x03) == 0x02);
                        DUK_ASSERT((DUK_OP_POSTDECR & 0x03) == 0x03);

                        tv1 = DUK__REGP(bc);
#if defined(DUK_USE_FASTINT)
                        if (DUK_TVAL_IS_FASTINT(tv1)) {
                                duk_int64_t x_fi, y_fi, z_fi;
                                x_fi = DUK_TVAL_GET_FASTINT(tv1);
                                if (ins & DUK_ENC_OP(0x01)) {
                                        if (x_fi == DUK_FASTINT_MIN) {
                                                goto skip_fastint;
                                        }
                                        y_fi = x_fi - 1;
                                } else {
                                        if (x_fi == DUK_FASTINT_MAX) {
                                                goto skip_fastint;
                                        }
                                        y_fi = x_fi + 1;
                                }

                                DUK_TVAL_SET_FASTINT(tv1, y_fi);  /* no need for refcount update */

                                tv2 = DUK__REGP(a);
                                z_fi = (ins & DUK_ENC_OP(0x02)) ? x_fi : y_fi;
                                DUK_TVAL_SET_FASTINT_UPDREF(thr, tv2, z_fi);  /* side effects */
                                break;
                        }
                 skip_fastint:
#endif
                        if (DUK_TVAL_IS_NUMBER(tv1)) {
                                /* Fast path for the case where the register
                                 * is a number (e.g. loop counter).
                                 */

                                x = DUK_TVAL_GET_NUMBER(tv1);
                                if (ins & DUK_ENC_OP(0x01)) {
                                        y = x - 1.0;
                                } else {
                                        y = x + 1.0;
                                }

                                DUK_TVAL_SET_NUMBER(tv1, y);  /* no need for refcount update */
                        } else {
                                x = duk_to_number(ctx, bc);

                                if (ins & DUK_ENC_OP(0x01)) {
                                        y = x - 1.0;
                                } else {
                                        y = x + 1.0;
                                }

                                duk_push_number(ctx, y);
                                duk_replace(ctx, bc);
                        }

                        tv2 = DUK__REGP(a);
                        z = (ins & DUK_ENC_OP(0x02)) ? x : y;
                        DUK_TVAL_SET_NUMBER_UPDREF(thr, tv2, z);  /* side effects */
                        break;
                }

                /* Preinc/predec for var-by-name, slow path. */
                case DUK_OP_PREINCV:
                case DUK_OP_PREDECV:
                case DUK_OP_POSTINCV:
                case DUK_OP_POSTDECV: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_activation *act;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_uint_fast_t bc = DUK_DEC_BC(ins);
                        duk_double_t x, y;
                        duk_tval *tv1;
                        duk_hstring *name;

                        /* Two lowest bits of opcode are used to distinguish
                         * variants.  Bit 0 = inc(0)/dec(1), bit 1 = pre(0)/post(1).
                         */
                        DUK_ASSERT((DUK_OP_PREINCV & 0x03) == 0x00);
                        DUK_ASSERT((DUK_OP_PREDECV & 0x03) == 0x01);
                        DUK_ASSERT((DUK_OP_POSTINCV & 0x03) == 0x02);
                        DUK_ASSERT((DUK_OP_POSTDECV & 0x03) == 0x03);

                        tv1 = DUK__CONSTP(bc);
                        DUK_ASSERT(DUK_TVAL_IS_STRING(tv1));
                        name = DUK_TVAL_GET_STRING(tv1);
                        DUK_ASSERT(name != NULL);
                        act = thr->callstack + thr->callstack_top - 1;
                        (void) duk_js_getvar_activation(thr, act, name, 1 /*throw*/);  /* -> [... val this] */

                        /* XXX: fastint fast path would be very useful here */

                        x = duk_to_number(ctx, -2);
                        duk_pop_2(ctx);
                        if (ins & DUK_ENC_OP(0x01)) {
                                y = x - 1.0;
                        } else {
                                y = x + 1.0;
                        }

                        duk_push_number(ctx, y);
                        tv1 = DUK_GET_TVAL_NEGIDX(ctx, -1);
                        DUK_ASSERT(tv1 != NULL);
                        duk_js_putvar_activation(thr, act, name, tv1, DUK__STRICT());
                        duk_pop(ctx);

                        duk_push_number(ctx, (ins & DUK_ENC_OP(0x02)) ? x : y);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                /* Preinc/predec for object properties. */
                case DUK_OP_PREINCP:
                case DUK_OP_PREDECP:
                case DUK_OP_POSTINCP:
                case DUK_OP_POSTDECP: {
                        duk_context *ctx = (duk_context *) thr;
                        duk_small_uint_fast_t a = DUK_DEC_A(ins);
                        duk_small_uint_fast_t b = DUK_DEC_B(ins);
                        duk_small_uint_fast_t c = DUK_DEC_C(ins);
                        duk_tval *tv_obj;
                        duk_tval *tv_key;
                        duk_tval *tv_val;
                        duk_bool_t rc;
                        duk_double_t x, y;

                        /* A -> target reg
                         * B -> object reg/const (may be const e.g. in "'foo'[1]")
                         * C -> key reg/const
                         */

                        /* Two lowest bits of opcode are used to distinguish
                         * variants.  Bit 0 = inc(0)/dec(1), bit 1 = pre(0)/post(1).
                         */
                        DUK_ASSERT((DUK_OP_PREINCP & 0x03) == 0x00);
                        DUK_ASSERT((DUK_OP_PREDECP & 0x03) == 0x01);
                        DUK_ASSERT((DUK_OP_POSTINCP & 0x03) == 0x02);
                        DUK_ASSERT((DUK_OP_POSTDECP & 0x03) == 0x03);

                        tv_obj = DUK__REGCONSTP(b);
                        tv_key = DUK__REGCONSTP(c);
                        rc = duk_hobject_getprop(thr, tv_obj, tv_key);  /* -> [val] */
                        DUK_UNREF(rc);  /* ignore */
                        tv_obj = NULL;  /* invalidated */
                        tv_key = NULL;  /* invalidated */

                        x = duk_to_number(ctx, -1);
                        duk_pop(ctx);
                        if (ins & DUK_ENC_OP(0x01)) {
                                y = x - 1.0;
                        } else {
                                y = x + 1.0;
                        }

                        duk_push_number(ctx, y);
                        tv_val = DUK_GET_TVAL_NEGIDX(ctx, -1);
                        DUK_ASSERT(tv_val != NULL);
                        tv_obj = DUK__REGCONSTP(b);
                        tv_key = DUK__REGCONSTP(c);
                        rc = duk_hobject_putprop(thr, tv_obj, tv_key, tv_val, DUK__STRICT());
                        DUK_UNREF(rc);  /* ignore */
                        tv_obj = NULL;  /* invalidated */
                        tv_key = NULL;  /* invalidated */
                        duk_pop(ctx);

                        duk_push_number(ctx, (ins & DUK_ENC_OP(0x02)) ? x : y);
                        duk_replace(ctx, (duk_idx_t) a);
                        break;
                }

                case DUK_OP_EXTRA: {
                        /* XXX: shared decoding of 'b' and 'c'? */

                        duk_small_uint_fast_t extraop = DUK_DEC_A(ins);
                        switch ((int) extraop) {
                        /* XXX: switch cast? */

                        case DUK_EXTRAOP_NOP: {
                                /* nop */
                                break;
                        }

                        case DUK_EXTRAOP_INVALID: {
                                DUK_ERROR_FMT1(thr, DUK_ERR_INTERNAL_ERROR, "INVALID opcode (%ld)", (long) DUK_DEC_BC(ins));
                                break;
                        }

                        case DUK_EXTRAOP_LDTHIS: {
                                /* Note: 'this' may be bound to any value, not just an object */
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
                                duk_tval *tv1, *tv2;

                                tv1 = DUK__REGP(bc);
                                tv2 = thr->valstack_bottom - 1;  /* 'this binding' is just under bottom */
                                DUK_ASSERT(tv2 >= thr->valstack);

                                DUK_DDD(DUK_DDDPRINT("LDTHIS: %!T to r%ld", (duk_tval *) tv2, (long) bc));

                                DUK_TVAL_SET_TVAL_UPDREF_FAST(thr, tv1, tv2);  /* side effects */
                                break;
                        }

                        case DUK_EXTRAOP_LDUNDEF: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
                                duk_tval *tv1;

                                tv1 = DUK__REGP(bc);
                                DUK_TVAL_SET_UNDEFINED_UPDREF(thr, tv1);  /* side effects */
                                break;
                        }

                        case DUK_EXTRAOP_LDNULL: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
                                duk_tval *tv1;

                                tv1 = DUK__REGP(bc);
                                DUK_TVAL_SET_NULL_UPDREF(thr, tv1);  /* side effects */
                                break;
                        }

                        case DUK_EXTRAOP_LDTRUE:
                        case DUK_EXTRAOP_LDFALSE: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
                                duk_tval *tv1;
                                duk_small_uint_fast_t bval = (extraop == DUK_EXTRAOP_LDTRUE ? 1 : 0);

                                tv1 = DUK__REGP(bc);
                                DUK_TVAL_SET_BOOLEAN_UPDREF(thr, tv1, bval);  /* side effects */
                                break;
                        }

                        case DUK_EXTRAOP_NEWOBJ: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);

                                duk_push_object(ctx);
                                duk_replace(ctx, (duk_idx_t) b);
                                break;
                        }

                        case DUK_EXTRAOP_NEWARR: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);

                                duk_push_array(ctx);
                                duk_replace(ctx, (duk_idx_t) b);
                                break;
                        }

                        case DUK_EXTRAOP_SETALEN: {
                                duk_small_uint_fast_t b;
                                duk_small_uint_fast_t c;
                                duk_tval *tv1;
                                duk_hobject *h;
                                duk_uint32_t len;

                                b = DUK_DEC_B(ins); tv1 = DUK__REGP(b);
                                DUK_ASSERT(DUK_TVAL_IS_OBJECT(tv1));
                                h = DUK_TVAL_GET_OBJECT(tv1);

                                c = DUK_DEC_C(ins); tv1 = DUK__REGP(c);
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv1));
                                len = (duk_uint32_t) DUK_TVAL_GET_NUMBER(tv1);

                                duk_hobject_set_length(thr, h, len);

                                break;
                        }

                        case DUK_EXTRAOP_TYPEOF: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
                                duk_push_hstring(ctx, duk_js_typeof(thr, DUK__REGP(bc)));
                                duk_replace(ctx, (duk_idx_t) bc);
                                break;
                        }

                        case DUK_EXTRAOP_TYPEOFID: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_activation *act;
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);
                                duk_small_uint_fast_t c = DUK_DEC_C(ins);
                                duk_hstring *name;
                                duk_tval *tv;

                                /* B -> target register
                                 * C -> constant index of identifier name
                                 */

                                tv = DUK__REGCONSTP(c);  /* XXX: this could be a DUK__CONSTP instead */
                                DUK_ASSERT(DUK_TVAL_IS_STRING(tv));
                                name = DUK_TVAL_GET_STRING(tv);
                                act = thr->callstack + thr->callstack_top - 1;
                                if (duk_js_getvar_activation(thr, act, name, 0 /*throw*/)) {
                                        /* -> [... val this] */
                                        tv = DUK_GET_TVAL_NEGIDX(ctx, -2);
                                        duk_push_hstring(ctx, duk_js_typeof(thr, tv));
                                        duk_replace(ctx, (duk_idx_t) b);
                                        duk_pop_2(ctx);
                                } else {
                                        /* unresolvable, no stack changes */
                                        duk_push_hstring_stridx(ctx, DUK_STRIDX_LC_UNDEFINED);
                                        duk_replace(ctx, (duk_idx_t) b);
                                }

                                break;
                        }

                        case DUK_EXTRAOP_INITENUM: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);
                                duk_small_uint_fast_t c = DUK_DEC_C(ins);

                                /*
                                 *  Enumeration semantics come from for-in statement, E5 Section 12.6.4.
                                 *  If called with 'null' or 'undefined', this opcode returns 'null' as
                                 *  the enumerator, which is special cased in NEXTENUM.  This simplifies
                                 *  the compiler part
                                 */

                                /* B -> register for writing enumerator object
                                 * C -> value to be enumerated (register)
                                 */

                                if (duk_is_null_or_undefined(ctx, (duk_idx_t) c)) {
                                        duk_push_null(ctx);
                                        duk_replace(ctx, (duk_idx_t) b);
                                } else {
                                        duk_dup(ctx, (duk_idx_t) c);
                                        duk_to_object(ctx, -1);
                                        duk_hobject_enumerator_create(ctx, 0 /*enum_flags*/);  /* [ ... val ] --> [ ... enum ] */
                                        duk_replace(ctx, (duk_idx_t) b);
                                }
                                break;
                        }

                        case DUK_EXTRAOP_NEXTENUM: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);
                                duk_small_uint_fast_t c = DUK_DEC_C(ins);

                                /*
                                 *  NEXTENUM checks whether the enumerator still has unenumerated
                                 *  keys.  If so, the next key is loaded to the target register
                                 *  and the next instruction is skipped.  Otherwise the next instruction
                                 *  will be executed, jumping out of the enumeration loop.
                                 */

                                /* B -> target register for next key
                                 * C -> enum register
                                 */

                                DUK_DDD(DUK_DDDPRINT("NEXTENUM: b->%!T, c->%!T",
                                                     (duk_tval *) duk_get_tval(ctx, (duk_idx_t) b),
                                                     (duk_tval *) duk_get_tval(ctx, (duk_idx_t) c)));

                                if (duk_is_object(ctx, (duk_idx_t) c)) {
                                        /* XXX: assert 'c' is an enumerator */
                                        duk_dup(ctx, (duk_idx_t) c);
                                        if (duk_hobject_enumerator_next(ctx, 0 /*get_value*/)) {
                                                /* [ ... enum ] -> [ ... next_key ] */
                                                DUK_DDD(DUK_DDDPRINT("enum active, next key is %!T, skip jump slot ",
                                                                     (duk_tval *) duk_get_tval(ctx, -1)));
                                                curr_pc++;
                                        } else {
                                                /* [ ... enum ] -> [ ... ] */
                                                DUK_DDD(DUK_DDDPRINT("enum finished, execute jump slot"));
                                                duk_push_undefined(ctx);
                                        }
                                        duk_replace(ctx, (duk_idx_t) b);
                                } else {
                                        /* 'null' enumerator case -> behave as with an empty enumerator */
                                        DUK_ASSERT(duk_is_null(ctx, (duk_idx_t) c));
                                        DUK_DDD(DUK_DDDPRINT("enum is null, execute jump slot"));
                                }
                                break;
                        }

                        case DUK_EXTRAOP_INITSET:
                        case DUK_EXTRAOP_INITSETI:
                        case DUK_EXTRAOP_INITGET:
                        case DUK_EXTRAOP_INITGETI: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_bool_t is_set = (extraop == DUK_EXTRAOP_INITSET || extraop == DUK_EXTRAOP_INITSETI);
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);
                                duk_uint_fast_t idx;

                                /* B -> object register
                                 * C -> C+0 contains key, C+1 closure (value)
                                 */

                                /*
                                 *  INITSET/INITGET are only used to initialize object literal keys.
                                 *  The compiler ensures that there cannot be a previous data property
                                 *  of the same name.  It also ensures that setter and getter can only
                                 *  be initialized once (or not at all).
                                 */

                                idx = (duk_uint_fast_t) DUK_DEC_C(ins);
                                if (extraop == DUK_EXTRAOP_INITSETI || extraop == DUK_EXTRAOP_INITGETI) {
                                        duk_tval *tv_ind = DUK__REGP(idx);
                                        DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv_ind));
                                        idx = (duk_uint_fast_t) DUK_TVAL_GET_NUMBER(tv_ind);
                                }

#if defined(DUK_USE_EXEC_INDIRECT_BOUND_CHECK)
                                if (idx + 2 > (duk_uint_fast_t) duk_get_top(ctx)) {
                                        /* XXX: use duk_is_valid_index() instead? */
                                        /* XXX: improve check; check against nregs, not against top */
                                        DUK__INTERNAL_ERROR("INITSET/INITGET out of bounds");
                                }
#endif

                                /* XXX: this is now a very unoptimal implementation -- this can be
                                 * made very simple by direct manipulation of the object internals,
                                 * given the guarantees above.
                                 */

                                duk_push_hobject_bidx(ctx, DUK_BIDX_OBJECT_CONSTRUCTOR);
                                duk_get_prop_stridx(ctx, -1, DUK_STRIDX_DEFINE_PROPERTY);
                                duk_push_undefined(ctx);
                                duk_dup(ctx, (duk_idx_t) b);
                                duk_dup(ctx, (duk_idx_t) (idx + 0));
                                duk_push_object(ctx);  /* -> [ Object defineProperty undefined obj key desc ] */

                                duk_push_true(ctx);
                                duk_put_prop_stridx(ctx, -2, DUK_STRIDX_ENUMERABLE);
                                duk_push_true(ctx);
                                duk_put_prop_stridx(ctx, -2, DUK_STRIDX_CONFIGURABLE);
                                duk_dup(ctx, (duk_idx_t) (idx + 1));
                                duk_put_prop_stridx(ctx, -2, (is_set ? DUK_STRIDX_SET : DUK_STRIDX_GET));

                                DUK_DDD(DUK_DDDPRINT("INITGET/INITSET: obj=%!T, key=%!T, desc=%!T",
                                                     (duk_tval *) duk_get_tval(ctx, -3),
                                                     (duk_tval *) duk_get_tval(ctx, -2),
                                                     (duk_tval *) duk_get_tval(ctx, -1)));

                                duk_call_method(ctx, 3);  /* -> [ Object res ] */
                                duk_pop_2(ctx);

                                DUK_DDD(DUK_DDDPRINT("INITGET/INITSET AFTER: obj=%!T",
                                                     (duk_tval *) duk_get_tval(ctx, (duk_idx_t) b)));
                                break;
                        }

                        case DUK_EXTRAOP_ENDTRY: {
                                duk_catcher *cat;
                                duk_tval *tv1;

                                DUK_ASSERT(thr->catchstack_top >= 1);
                                DUK_ASSERT(thr->callstack_top >= 1);
                                DUK_ASSERT(thr->catchstack[thr->catchstack_top - 1].callstack_index == thr->callstack_top - 1);

                                cat = thr->catchstack + thr->catchstack_top - 1;

                                DUK_DDD(DUK_DDDPRINT("ENDTRY: clearing catch active flag (regardless of whether it was set or not)"));
                                DUK_CAT_CLEAR_CATCH_ENABLED(cat);

                                if (DUK_CAT_HAS_FINALLY_ENABLED(cat)) {
                                        DUK_DDD(DUK_DDDPRINT("ENDTRY: finally part is active, jump through 2nd jump slot with 'normal continuation'"));

                                        tv1 = thr->valstack + cat->idx_base;
                                        DUK_ASSERT(tv1 >= thr->valstack && tv1 < thr->valstack_top);
                                        DUK_TVAL_SET_UNDEFINED_UPDREF(thr, tv1);  /* side effects */
                                        tv1 = NULL;

                                        tv1 = thr->valstack + cat->idx_base + 1;
                                        DUK_ASSERT(tv1 >= thr->valstack && tv1 < thr->valstack_top);
                                        DUK_TVAL_SET_FASTINT_U32_UPDREF(thr, tv1, (duk_uint32_t) DUK_LJ_TYPE_NORMAL);  /* side effects */
                                        tv1 = NULL;

                                        DUK_CAT_CLEAR_FINALLY_ENABLED(cat);
                                } else {
                                        DUK_DDD(DUK_DDDPRINT("ENDTRY: no finally part, dismantle catcher, jump through 2nd jump slot (to end of statement)"));
                                        duk_hthread_catchstack_unwind(thr, thr->catchstack_top - 1);
                                        /* no need to unwind callstack */
                                }

                                curr_pc = cat->pc_base + 1;
                                break;
                        }

                        case DUK_EXTRAOP_ENDCATCH: {
                                duk_activation *act;
                                duk_catcher *cat;
                                duk_tval *tv1;

                                DUK_ASSERT(thr->catchstack_top >= 1);
                                DUK_ASSERT(thr->callstack_top >= 1);
                                DUK_ASSERT(thr->catchstack[thr->catchstack_top - 1].callstack_index == thr->callstack_top - 1);

                                cat = thr->catchstack + thr->catchstack_top - 1;
                                DUK_ASSERT(!DUK_CAT_HAS_CATCH_ENABLED(cat));  /* cleared before entering catch part */

                                act = thr->callstack + thr->callstack_top - 1;

                                if (DUK_CAT_HAS_LEXENV_ACTIVE(cat)) {
                                        duk_hobject *prev_env;

                                        /* 'with' binding has no catch clause, so can't be here unless a normal try-catch */
                                        DUK_ASSERT(DUK_CAT_HAS_CATCH_BINDING_ENABLED(cat));
                                        DUK_ASSERT(act->lex_env != NULL);

                                        DUK_DDD(DUK_DDDPRINT("ENDCATCH: popping catcher part lexical environment"));

                                        prev_env = act->lex_env;
                                        DUK_ASSERT(prev_env != NULL);
                                        act->lex_env = DUK_HOBJECT_GET_PROTOTYPE(thr->heap, prev_env);
                                        DUK_CAT_CLEAR_LEXENV_ACTIVE(cat);
                                        DUK_HOBJECT_DECREF(thr, prev_env);  /* side effects */
                                }

                                if (DUK_CAT_HAS_FINALLY_ENABLED(cat)) {
                                        DUK_DDD(DUK_DDDPRINT("ENDCATCH: finally part is active, jump through 2nd jump slot with 'normal continuation'"));

                                        tv1 = thr->valstack + cat->idx_base;
                                        DUK_ASSERT(tv1 >= thr->valstack && tv1 < thr->valstack_top);
                                        DUK_TVAL_SET_UNDEFINED_UPDREF(thr, tv1);  /* side effects */
                                        tv1 = NULL;

                                        tv1 = thr->valstack + cat->idx_base + 1;
                                        DUK_ASSERT(tv1 >= thr->valstack && tv1 < thr->valstack_top);
                                        DUK_TVAL_SET_FASTINT_U32_UPDREF(thr, tv1, (duk_uint32_t) DUK_LJ_TYPE_NORMAL);  /* side effects */
                                        tv1 = NULL;

                                        DUK_CAT_CLEAR_FINALLY_ENABLED(cat);
                                } else {
                                        DUK_DDD(DUK_DDDPRINT("ENDCATCH: no finally part, dismantle catcher, jump through 2nd jump slot (to end of statement)"));
                                        duk_hthread_catchstack_unwind(thr, thr->catchstack_top - 1);
                                        /* no need to unwind callstack */
                                }

                                curr_pc = cat->pc_base + 1;
                                break;
                        }

                        case DUK_EXTRAOP_ENDFIN: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_catcher *cat;
                                duk_tval *tv1;
                                duk_small_uint_t cont_type;
                                duk_small_uint_t ret_result;

                                /* Sync and NULL early. */
                                DUK__SYNC_AND_NULL_CURR_PC();

                                DUK_ASSERT(thr->catchstack_top >= 1);
                                DUK_ASSERT(thr->callstack_top >= 1);
                                DUK_ASSERT(thr->catchstack[thr->catchstack_top - 1].callstack_index == thr->callstack_top - 1);

                                cat = thr->catchstack + thr->catchstack_top - 1;

                                /* CATCH flag may be enabled or disabled here; it may be enabled if
                                 * the statement has a catch block but the try block does not throw
                                 * an error.
                                 */
                                DUK_ASSERT(!DUK_CAT_HAS_FINALLY_ENABLED(cat));  /* cleared before entering finally */
                                /* XXX: assert idx_base */

                                DUK_DDD(DUK_DDDPRINT("ENDFIN: completion value=%!T, type=%!T",
                                                     (duk_tval *) (thr->valstack + cat->idx_base + 0),
                                                     (duk_tval *) (thr->valstack + cat->idx_base + 1)));

                                tv1 = thr->valstack + cat->idx_base + 1;  /* type */
                                DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv1));
                                cont_type = (duk_small_uint_t) DUK_TVAL_GET_NUMBER(tv1);

                                switch (cont_type) {
                                case DUK_LJ_TYPE_NORMAL: {
                                        DUK_DDD(DUK_DDDPRINT("ENDFIN: finally part finishing with 'normal' (non-abrupt) completion -> "
                                                             "dismantle catcher, resume execution after ENDFIN"));
                                        duk_hthread_catchstack_unwind(thr, thr->catchstack_top - 1);
                                        /* no need to unwind callstack */
                                        goto restart_execution;
                                }
                                case DUK_LJ_TYPE_RETURN: {
                                        DUK_DDD(DUK_DDDPRINT("ENDFIN: finally part finishing with 'return' complation -> dismantle "
                                                             "catcher, handle return, lj.value1=%!T", thr->valstack + cat->idx_base));

                                        /* Not necessary to unwind catchstack: return handling will
                                         * do it.  The finally flag of 'cat' is no longer set.  The
                                         * catch flag may be set, but it's not checked by return handling.
                                         */
                                        DUK_ASSERT(!DUK_CAT_HAS_FINALLY_ENABLED(cat));  /* cleared before entering finally */
#if 0
                                        duk_hthread_catchstack_unwind(thr, thr->catchstack_top - 1);
#endif

                                        duk_push_tval(ctx, thr->valstack + cat->idx_base);
                                        ret_result = duk__handle_return(thr,
                                                                        entry_thread,
                                                                        entry_callstack_top);
                                        if (ret_result == DUK__RETHAND_RESTART) {
                                                goto restart_execution;
                                        }
                                        DUK_ASSERT(ret_result == DUK__RETHAND_FINISHED);

                                        DUK_DDD(DUK_DDDPRINT("exiting executor after ENDFIN and RETURN (pseudo) longjmp type"));
                                        return;
                                }
                                case DUK_LJ_TYPE_BREAK:
                                case DUK_LJ_TYPE_CONTINUE: {
                                        duk_uint_t label_id;
                                        duk_small_uint_t lj_type;

                                        /* Not necessary to unwind catchstack: break/continue
                                         * handling will do it.  The finally flag of 'cat' is
                                         * no longer set.  The catch flag may be set, but it's
                                         * not checked by break/continue handling.
                                         */
#if 0
                                        duk_hthread_catchstack_unwind(thr, thr->catchstack_top - 1);
#endif

                                        tv1 = thr->valstack + cat->idx_base;
                                        DUK_ASSERT(DUK_TVAL_IS_NUMBER(tv1));
#if defined(DUK_USE_FASTINT)
                                        DUK_ASSERT(DUK_TVAL_IS_FASTINT(tv1));
                                        label_id = (duk_small_uint_t) DUK_TVAL_GET_FASTINT_U32(tv1);
#else
                                        label_id = (duk_small_uint_t) DUK_TVAL_GET_NUMBER(tv1);
#endif
                                        lj_type = cont_type;
                                        duk__handle_break_or_continue(thr, label_id, lj_type);
                                        goto restart_execution;
                                }
                                default: {
                                        DUK_DDD(DUK_DDDPRINT("ENDFIN: finally part finishing with abrupt completion, lj_type=%ld -> "
                                                             "dismantle catcher, re-throw error",
                                                             (long) cont_type));

                                        duk_push_tval(ctx, thr->valstack + cat->idx_base);

                                        duk_err_setup_heap_ljstate(thr, (duk_small_int_t) cont_type);

                                        DUK_ASSERT(thr->heap->lj.jmpbuf_ptr != NULL);  /* always in executor */
                                        duk_err_longjmp(thr);
                                        DUK_UNREACHABLE();
                                }
                                }

                                /* Must restart in all cases because we NULLed thr->ptr_curr_pc. */
                                DUK_UNREACHABLE();
                                break;
                        }

                        case DUK_EXTRAOP_THROW: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);

                                /* Note: errors are augmented when they are created, not
                                 * when they are thrown.  So, don't augment here, it would
                                 * break re-throwing for instance.
                                 */

                                /* Sync so that augmentation sees up-to-date activations, NULL
                                 * thr->ptr_curr_pc so that it's not used if side effects occur
                                 * in augmentation or longjmp handling.
                                 */
                                DUK__SYNC_AND_NULL_CURR_PC();

                                duk_dup(ctx, (duk_idx_t) bc);
                                DUK_DDD(DUK_DDDPRINT("THROW ERROR (BYTECODE): %!dT (before throw augment)",
                                                     (duk_tval *) duk_get_tval(ctx, -1)));
#if defined(DUK_USE_AUGMENT_ERROR_THROW)
                                duk_err_augment_error_throw(thr);
                                DUK_DDD(DUK_DDDPRINT("THROW ERROR (BYTECODE): %!dT (after throw augment)",
                                                     (duk_tval *) duk_get_tval(ctx, -1)));
#endif

                                duk_err_setup_heap_ljstate(thr, DUK_LJ_TYPE_THROW);

                                DUK_ASSERT(thr->heap->lj.jmpbuf_ptr != NULL);  /* always in executor */
                                duk_err_longjmp(thr);
                                DUK_UNREACHABLE();
                                break;
                        }

                        case DUK_EXTRAOP_INVLHS: {
                                DUK_ERROR(thr, DUK_ERR_REFERENCE_ERROR, "invalid lvalue");

                                DUK_UNREACHABLE();
                                break;
                        }

                        case DUK_EXTRAOP_UNM:
                        case DUK_EXTRAOP_UNP: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
                                duk__vm_arith_unary_op(thr, DUK__REGP(bc), bc, extraop);
                                break;
                        }

                        case DUK_EXTRAOP_DEBUGGER: {
                                /* Opcode only emitted by compiler when debugger
                                 * support is enabled.  Ignore it silently without
                                 * debugger support, in case it has been loaded
                                 * from precompiled bytecode.
                                 */
#if defined(DUK_USE_DEBUGGER_SUPPORT)
                                if (DUK_HEAP_IS_DEBUGGER_ATTACHED(thr->heap)) {
                                        DUK_D(DUK_DPRINT("DEBUGGER statement encountered, halt execution"));
                                        DUK__SYNC_AND_NULL_CURR_PC();
                                        duk_debug_halt_execution(thr, 1 /*use_prev_pc*/);
                                        DUK_D(DUK_DPRINT("DEBUGGER statement finished, resume execution"));
                                        goto restart_execution;
                                } else {
                                        DUK_D(DUK_DPRINT("DEBUGGER statement ignored, debugger not attached"));
                                }
#else
                                DUK_D(DUK_DPRINT("DEBUGGER statement ignored, no debugger support"));
#endif
                                break;
                        }

                        case DUK_EXTRAOP_BREAK: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);

                                DUK_DDD(DUK_DDDPRINT("BREAK: %ld", (long) bc));

                                DUK__SYNC_AND_NULL_CURR_PC();
                                duk__handle_break_or_continue(thr, (duk_uint_t) bc, DUK_LJ_TYPE_BREAK);
                                goto restart_execution;
                        }

                        case DUK_EXTRAOP_CONTINUE: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);

                                DUK_DDD(DUK_DDDPRINT("CONTINUE: %ld", (long) bc));

                                DUK__SYNC_AND_NULL_CURR_PC();
                                duk__handle_break_or_continue(thr, (duk_uint_t) bc, DUK_LJ_TYPE_CONTINUE);
                                goto restart_execution;
                        }

                        case DUK_EXTRAOP_BNOT: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);

                                duk__vm_bitwise_not(thr, DUK__REGP(bc), bc);
                                break;
                        }

                        case DUK_EXTRAOP_LNOT: {
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
                                duk_tval *tv1;

                                tv1 = DUK__REGP(bc);
                                duk__vm_logical_not(thr, tv1, tv1);
                                break;
                        }

                        case DUK_EXTRAOP_INSTOF: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);
                                duk_small_uint_fast_t c = DUK_DEC_C(ins);
                                duk_bool_t tmp;

                                tmp = duk_js_instanceof(thr, DUK__REGP(b), DUK__REGCONSTP(c));
                                duk_push_boolean(ctx, tmp);
                                duk_replace(ctx, (duk_idx_t) b);
                                break;
                        }

                        case DUK_EXTRAOP_IN: {
                                duk_context *ctx = (duk_context *) thr;
                                duk_small_uint_fast_t b = DUK_DEC_B(ins);
                                duk_small_uint_fast_t c = DUK_DEC_C(ins);
                                duk_bool_t tmp;

                                tmp = duk_js_in(thr, DUK__REGP(b), DUK__REGCONSTP(c));
                                duk_push_boolean(ctx, tmp);
                                duk_replace(ctx, (duk_idx_t) b);
                                break;
                        }

                        case DUK_EXTRAOP_LABEL: {
                                duk_catcher *cat;
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);

                                /* allocate catcher and populate it (should be atomic) */

                                duk_hthread_catchstack_grow(thr);
                                cat = thr->catchstack + thr->catchstack_top;
                                thr->catchstack_top++;

                                cat->flags = DUK_CAT_TYPE_LABEL | (bc << DUK_CAT_LABEL_SHIFT);
                                cat->callstack_index = thr->callstack_top - 1;
                                cat->pc_base = (duk_instr_t *) curr_pc;  /* pre-incremented, points to first jump slot */
                                cat->idx_base = 0;  /* unused for label */
                                cat->h_varname = NULL;

                                DUK_DDD(DUK_DDDPRINT("LABEL catcher: flags=0x%08lx, callstack_index=%ld, pc_base=%ld, "
                                                     "idx_base=%ld, h_varname=%!O, label_id=%ld",
                                                     (long) cat->flags, (long) cat->callstack_index, (long) cat->pc_base,
                                                     (long) cat->idx_base, (duk_heaphdr *) cat->h_varname, (long) DUK_CAT_GET_LABEL(cat)));

                                curr_pc += 2;  /* skip jump slots */
                                break;
                        }

                        case DUK_EXTRAOP_ENDLABEL: {
                                duk_catcher *cat;
#if defined(DUK_USE_DDDPRINT) || defined(DUK_USE_ASSERTIONS)
                                duk_uint_fast_t bc = DUK_DEC_BC(ins);
#endif
#if defined(DUK_USE_DDDPRINT)
                                DUK_DDD(DUK_DDDPRINT("ENDLABEL %ld", (long) bc));
#endif

                                DUK_ASSERT(thr->catchstack_top >= 1);

                                cat = thr->catchstack + thr->catchstack_top - 1;
                                DUK_UNREF(cat);
                                DUK_ASSERT(DUK_CAT_GET_TYPE(cat) == DUK_CAT_TYPE_LABEL);
                                DUK_ASSERT((duk_uint_fast_t) DUK_CAT_GET_LABEL(cat) == bc);

                                duk_hthread_catchstack_unwind(thr, thr->catchstack_top - 1);
                                /* no need to unwind callstack */
                                break;
                        }

                        default: {
                                DUK__INTERNAL_ERROR("invalid extra opcode");
                        }

                        }  /* end switch */

                        break;
                }

                default: {
                        /* this should never be possible, because the switch-case is
                         * comprehensive
                         */
                        DUK__INTERNAL_ERROR("invalid opcode");
                        break;
                }

                }  /* end switch */
        }
        DUK_UNREACHABLE();

#ifndef DUK_USE_VERBOSE_EXECUTOR_ERRORS
 internal_error:
        DUK_ERROR_INTERNAL(thr, "internal error in bytecode executor");
#endif
}

#undef DUK__LONGJMP_RESTART
#undef DUK__LONGJMP_FINISHED
#undef DUK__LONGJMP_RETHROW

#undef DUK__RETHAND_RESTART
#undef DUK__RETHAND_FINISHED

#undef DUK__FUN
#undef DUK__STRICT
#undef DUK__REG
#undef DUK__REGP
#undef DUK__CONST
#undef DUK__CONSTP
#undef DUK__RCISREG
#undef DUK__REGCONST
#undef DUK__REGCONSTP

#undef DUK__INTERNAL_ERROR
#undef DUK__SYNC_CURR_PC
#undef DUK__SYNC_AND_NULL_CURR_PC