ceph/src/boost/tools/build/src/engine/boehm_gc/include/private/gc_pmark.h

   1 /*
   2  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
   3  * Copyright (c) 2001 by Hewlett-Packard Company. All rights reserved.
   4  *
   5  * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
   6  * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
   7  *
   8  * Permission is hereby granted to use or copy this program
   9  * for any purpose,  provided the above notices are retained on all copies.
  10  * Permission to modify the code and to distribute modified code is granted,
  11  * provided the above notices are retained, and a notice that the code was
  12  * modified is included with the above copyright notice.
  13  *
  14  */
  15
  16 /* Private declarations of GC marker data structures and macros */
  17
  18 /*
  19  * Declarations of mark stack.  Needed by marker and client supplied mark
  20  * routines.  Transitively include gc_priv.h.
  21  * (Note that gc_priv.h should not be included before this, since this
  22  * includes dbg_mlc.h, which wants to include gc_priv.h AFTER defining
  23  * I_HIDE_POINTERS.)
  24  */
  25 #ifndef GC_PMARK_H
  26 # define GC_PMARK_H
  27
  28 # if defined(KEEP_BACK_PTRS) || defined(PRINT_BLACK_LIST)
  29 #   include "dbg_mlc.h"
  30 # endif
  31 # ifndef GC_MARK_H
  32 #   include "../gc_mark.h"
  33 # endif
  34 # ifndef GC_PRIVATE_H
  35 #   include "gc_priv.h"
  36 # endif
  37
  38 /* The real declarations of the following is in gc_priv.h, so that      */
  39 /* we can avoid scanning the following table.                           */
  40 /*
  41 extern mark_proc GC_mark_procs[MAX_MARK_PROCS];
  42 */
  43
  44 /*
  45  * Mark descriptor stuff that should remain private for now, mostly
  46  * because it's hard to export WORDSZ without including gcconfig.h.
  47  */
  48 # define BITMAP_BITS (WORDSZ - GC_DS_TAG_BITS)
  49 # define PROC(descr) \
  50         (GC_mark_procs[((descr) >> GC_DS_TAG_BITS) & (GC_MAX_MARK_PROCS-1)])
  51 # define ENV(descr) \
  52         ((descr) >> (GC_DS_TAG_BITS + GC_LOG_MAX_MARK_PROCS))
  53 # define MAX_ENV \
  54         (((word)1 << (WORDSZ - GC_DS_TAG_BITS - GC_LOG_MAX_MARK_PROCS)) - 1)
  55
  56
  57 extern unsigned GC_n_mark_procs;
  58
  59 /* Number of mark stack entries to discard on overflow. */
  60 #define GC_MARK_STACK_DISCARDS (INITIAL_MARK_STACK_SIZE/8)
  61
  62 typedef struct GC_ms_entry {
  63     ptr_t mse_start;   /* First word of object */
  64     GC_word mse_descr;  /* Descriptor; low order two bits are tags,     */
  65                         /* identifying the upper 30 bits as one of the  */
  66                         /* following:                                   */
  67 } mse;
  68
  69 extern size_t GC_mark_stack_size;
  70
  71 extern mse * GC_mark_stack_limit;
  72
  73 #ifdef PARALLEL_MARK
  74   extern mse * volatile GC_mark_stack_top;
  75 #else
  76   extern mse * GC_mark_stack_top;
  77 #endif
  78
  79 extern mse * GC_mark_stack;
  80
  81 #ifdef PARALLEL_MARK
  82     /*
  83      * Allow multiple threads to participate in the marking process.
  84      * This works roughly as follows:
  85      *  The main mark stack never shrinks, but it can grow.
  86      *
  87      *  The initiating threads holds the GC lock, and sets GC_help_wanted.
  88      *
  89      *  Other threads:
  90      *     1) update helper_count (while holding mark_lock.)
  91      *     2) allocate a local mark stack
  92      *     repeatedly:
  93      *          3) Steal a global mark stack entry by atomically replacing
  94      *             its descriptor with 0.
  95      *          4) Copy it to the local stack.
  96      *          5) Mark on the local stack until it is empty, or
  97      *             it may be profitable to copy it back.
  98      *          6) If necessary, copy local stack to global one,
  99      *             holding mark lock.
 100      *    7) Stop when the global mark stack is empty.
 101      *    8) decrement helper_count (holding mark_lock).
 102      *
 103      * This is an experiment to see if we can do something along the lines
 104      * of the University of Tokyo SGC in a less intrusive, though probably
 105      * also less performant, way.
 106      */
 107     void GC_do_parallel_mark();
 108                 /* inititate parallel marking.  */
 109
 110     extern GC_bool GC_help_wanted;      /* Protected by mark lock       */
 111     extern unsigned GC_helper_count;    /* Number of running helpers.   */
 112                                         /* Protected by mark lock       */
 113     extern unsigned GC_active_count;    /* Number of active helpers.    */
 114                                         /* Protected by mark lock       */
 115                                         /* May increase and decrease    */
 116                                         /* within each mark cycle.  But */
 117                                         /* once it returns to 0, it     */
 118                                         /* stays zero for the cycle.    */
 119     /* GC_mark_stack_top is also protected by mark lock.        */
 120     /*
 121      * GC_notify_all_marker() is used when GC_help_wanted is first set,
 122      * when the last helper becomes inactive,
 123      * when something is added to the global mark stack, and just after
 124      * GC_mark_no is incremented.
 125      * This could be split into multiple CVs (and probably should be to
 126      * scale to really large numbers of processors.)
 127      */
 128 #endif /* PARALLEL_MARK */
 129
 130 /* Return a pointer to within 1st page of object.       */
 131 /* Set *new_hdr_p to corr. hdr.                         */
 132 ptr_t GC_find_start(ptr_t current, hdr *hhdr, hdr **new_hdr_p);
 133
 134 mse * GC_signal_mark_stack_overflow(mse *msp);
 135
 136 /* Push the object obj with corresponding heap block header hhdr onto   */
 137 /* the mark stack.                                                      */
 138 # define PUSH_OBJ(obj, hhdr, mark_stack_top, mark_stack_limit) \
 139 { \
 140     register word _descr = (hhdr) -> hb_descr; \
 141         \
 142     if (_descr != 0) { \
 143         mark_stack_top++; \
 144         if (mark_stack_top >= mark_stack_limit) { \
 145           mark_stack_top = GC_signal_mark_stack_overflow(mark_stack_top); \
 146         } \
 147         mark_stack_top -> mse_start = (obj); \
 148         mark_stack_top -> mse_descr = _descr; \
 149     } \
 150 }
 151
 152 /* Push the contents of current onto the mark stack if it is a valid    */
 153 /* ptr to a currently unmarked object.  Mark it.                        */
 154 /* If we assumed a standard-conforming compiler, we could probably      */
 155 /* generate the exit_label transparently.                               */
 156 # define PUSH_CONTENTS(current, mark_stack_top, mark_stack_limit, \
 157                        source, exit_label) \
 158 { \
 159     hdr * my_hhdr; \
 160  \
 161     HC_GET_HDR(current, my_hhdr, source, exit_label); \
 162     PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
 163                   source, exit_label, my_hhdr, TRUE);   \
 164 exit_label: ; \
 165 }
 166
 167 /* Set mark bit, exit if it was already set.    */
 168
 169 # ifdef USE_MARK_BITS
 170 #   ifdef PARALLEL_MARK
 171       /* The following may fail to exit even if the bit was already set.    */
 172       /* For our uses, that's benign:                                       */
 173 #     define OR_WORD_EXIT_IF_SET(addr, bits, exit_label) \
 174         { \
 175           if (!(*(addr) & (mask))) { \
 176             AO_or((AO_t *)(addr), (mask); \
 177           } else { \
 178             goto label; \
 179           } \
 180         }
 181 #   else
 182 #     define OR_WORD_EXIT_IF_SET(addr, bits, exit_label) \
 183         { \
 184            word old = *(addr); \
 185            word my_bits = (bits); \
 186            if (old & my_bits) goto exit_label; \
 187            *(addr) = (old | my_bits); \
 188          }
 189 #   endif /* !PARALLEL_MARK */
 190 #   define SET_MARK_BIT_EXIT_IF_SET(hhdr,bit_no,exit_label) \
 191     { \
 192         word * mark_word_addr = hhdr -> hb_marks + divWORDSZ(bit_no); \
 193       \
 194         OR_WORD_EXIT_IF_SET(mark_word_addr, (word)1 << modWORDSZ(bit_no), \
 195                             exit_label); \
 196     }
 197 # endif
 198
 199
 200 #ifdef USE_MARK_BYTES
 201 # if defined(I386) && defined(__GNUC__)
 202 #  define LONG_MULT(hprod, lprod, x, y) { \
 203         asm("mull %2" : "=a"(lprod), "=d"(hprod) : "g"(y), "0"(x)); \
 204    }
 205 # else /* No in-line X86 assembly code */
 206 #  define LONG_MULT(hprod, lprod, x, y) { \
 207         unsigned long long prod = (unsigned long long)x \
 208                                   * (unsigned long long)y; \
 209         hprod = prod >> 32;  \
 210         lprod = (unsigned32)prod;  \
 211    }
 212 # endif
 213
 214   /* There is a race here, and we may set                               */
 215   /* the bit twice in the concurrent case.  This can result in the      */
 216   /* object being pushed twice.  But that's only a performance issue.   */
 217 # define SET_MARK_BIT_EXIT_IF_SET(hhdr,bit_no,exit_label) \
 218     { \
 219         char * mark_byte_addr = (char *)hhdr -> hb_marks + (bit_no); \
 220         char mark_byte = *mark_byte_addr; \
 221           \
 222         if (mark_byte) goto exit_label; \
 223         *mark_byte_addr = 1;  \
 224     }
 225 #endif /* USE_MARK_BYTES */
 226
 227 #ifdef PARALLEL_MARK
 228 # define INCR_MARKS(hhdr) \
 229         AO_store(&(hhdr -> hb_n_marks), AO_load(&(hhdr -> hb_n_marks))+1);
 230 #else
 231 # define INCR_MARKS(hhdr) ++(hhdr -> hb_n_marks)
 232 #endif
 233
 234 #ifdef ENABLE_TRACE
 235 # define TRACE(source, cmd) \
 236         if (GC_trace_addr != 0 && (ptr_t)(source) == GC_trace_addr) cmd
 237 # define TRACE_TARGET(target, cmd) \
 238         if (GC_trace_addr != 0 && (target) == *(ptr_t *)GC_trace_addr) cmd
 239 #else
 240 # define TRACE(source, cmd)
 241 # define TRACE_TARGET(source, cmd)
 242 #endif
 243 /* If the mark bit corresponding to current is not set, set it, and     */
 244 /* push the contents of the object on the mark stack.  Current points   */
 245 /* to the bginning of the object.  We rely on the fact that the         */
 246 /* preceding header calculation will succeed for a pointer past the     */
 247 /* forst page of an object, only if it is in fact a valid pointer       */
 248 /* to the object.  Thus we can omit the otherwise necessary tests       */
 249 /* here.  Note in particular tha the "displ" value is the displacement  */
 250 /* from the beggining of the heap block, which may itself be in the     */
 251 /* interior of a large object.                                          */
 252 #ifdef MARK_BIT_PER_GRANULE
 253 # define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
 254                            source, exit_label, hhdr, do_offset_check) \
 255 { \
 256     size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
 257     /* displ is always within range.  If current doesn't point to       */ \
 258     /* first block, then we are in the all_interior_pointers case, and  */ \
 259     /* it is safe to use any displacement value.                        */ \
 260     size_t gran_displ = BYTES_TO_GRANULES(displ); \
 261     size_t gran_offset = hhdr -> hb_map[gran_displ];    \
 262     size_t byte_offset = displ & (GRANULE_BYTES - 1); \
 263     ptr_t base = current;  \
 264     /* The following always fails for large block references. */ \
 265     if (EXPECT((gran_offset | byte_offset) != 0, FALSE))  { \
 266         if (hhdr -> hb_large_block) { \
 267           /* gran_offset is bogus.      */ \
 268           size_t obj_displ; \
 269           base = (ptr_t)(hhdr -> hb_block); \
 270           obj_displ = (ptr_t)(current) - base;  \
 271           if (obj_displ != displ) { \
 272             GC_ASSERT(obj_displ < hhdr -> hb_sz); \
 273             /* Must be in all_interior_pointer case, not first block */ \
 274             /* already did validity check on cache miss.             */ \
 275             ; \
 276           } else { \
 277             if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 278               GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 279               goto exit_label; \
 280             } \
 281           } \
 282           gran_displ = 0; \
 283           GC_ASSERT(hhdr -> hb_sz > HBLKSIZE || \
 284                     hhdr -> hb_block == HBLKPTR(current)); \
 285           GC_ASSERT((ptr_t)(hhdr -> hb_block) <= (ptr_t) current); \
 286         } else { \
 287           size_t obj_displ = GRANULES_TO_BYTES(gran_offset) \
 288                              + byte_offset; \
 289           if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 290             GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 291             goto exit_label; \
 292           } \
 293           gran_displ -= gran_offset; \
 294           base -= obj_displ; \
 295         } \
 296     } \
 297     GC_ASSERT(hhdr == GC_find_header(base)); \
 298     GC_ASSERT(gran_displ % BYTES_TO_GRANULES(hhdr -> hb_sz) == 0); \
 299     TRACE(source, GC_log_printf("GC:%d: passed validity tests\n",GC_gc_no)); \
 300     SET_MARK_BIT_EXIT_IF_SET(hhdr, gran_displ, exit_label); \
 301     TRACE(source, GC_log_printf("GC:%d: previously unmarked\n",GC_gc_no)); \
 302     TRACE_TARGET(base, \
 303         GC_log_printf("GC:%d: marking %p from %p instead\n", GC_gc_no, \
 304                       base, source)); \
 305     INCR_MARKS(hhdr); \
 306     GC_STORE_BACK_PTR((ptr_t)source, base); \
 307     PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
 308 }
 309 #endif /* MARK_BIT_PER_GRANULE */
 310
 311 #ifdef MARK_BIT_PER_OBJ
 312 # define PUSH_CONTENTS_HDR(current, mark_stack_top, mark_stack_limit, \
 313                            source, exit_label, hhdr, do_offset_check) \
 314 { \
 315     size_t displ = HBLKDISPL(current); /* Displacement in block; in bytes. */\
 316     unsigned32 low_prod, high_prod, offset_fraction; \
 317     unsigned32 inv_sz = hhdr -> hb_inv_sz; \
 318     ptr_t base = current;  \
 319     LONG_MULT(high_prod, low_prod, displ, inv_sz); \
 320     /* product is > and within sz_in_bytes of displ * sz_in_bytes * 2**32 */ \
 321     if (EXPECT(low_prod >> 16 != 0, FALSE))  { \
 322             FIXME: fails if offset is a multiple of HBLKSIZE which becomes 0 \
 323         if (inv_sz == LARGE_INV_SZ) { \
 324           size_t obj_displ; \
 325           base = (ptr_t)(hhdr -> hb_block); \
 326           obj_displ = (ptr_t)(current) - base;  \
 327           if (obj_displ != displ) { \
 328             GC_ASSERT(obj_displ < hhdr -> hb_sz); \
 329             /* Must be in all_interior_pointer case, not first block */ \
 330             /* already did validity check on cache miss.             */ \
 331             ; \
 332           } else { \
 333             if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 334               GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 335               goto exit_label; \
 336             } \
 337           } \
 338           GC_ASSERT(hhdr -> hb_sz > HBLKSIZE || \
 339                     hhdr -> hb_block == HBLKPTR(current)); \
 340           GC_ASSERT((ptr_t)(hhdr -> hb_block) < (ptr_t) current); \
 341         } else { \
 342           /* Accurate enough if HBLKSIZE <= 2**15.      */ \
 343           GC_ASSERT(HBLKSIZE <= (1 << 15)); \
 344           size_t obj_displ = (((low_prod >> 16) + 1) * (hhdr -> hb_sz)) >> 16; \
 345           if (do_offset_check && !GC_valid_offsets[obj_displ]) { \
 346             GC_ADD_TO_BLACK_LIST_NORMAL(current, source); \
 347             goto exit_label; \
 348           } \
 349           base -= obj_displ; \
 350         } \
 351     } \
 352     /* May get here for pointer to start of block not at        */ \
 353     /* beginning of object.  If so, it's valid, and we're fine. */ \
 354     GC_ASSERT(high_prod >= 0 && high_prod <= HBLK_OBJS(hhdr -> hb_sz)); \
 355     TRACE(source, GC_log_printf("GC:%d: passed validity tests\n",GC_gc_no)); \
 356     SET_MARK_BIT_EXIT_IF_SET(hhdr, high_prod, exit_label); \
 357     TRACE(source, GC_log_printf("GC:%d: previously unmarked\n",GC_gc_no)); \
 358     TRACE_TARGET(base, \
 359         GC_log_printf("GC:%d: marking %p from %p instead\n", GC_gc_no, \
 360                       base, source)); \
 361     INCR_MARKS(hhdr); \
 362     GC_STORE_BACK_PTR((ptr_t)source, base); \
 363     PUSH_OBJ(base, hhdr, mark_stack_top, mark_stack_limit); \
 364 }
 365 #endif /* MARK_BIT_PER_OBJ */
 366
 367 #if defined(PRINT_BLACK_LIST) || defined(KEEP_BACK_PTRS)
 368 #   define PUSH_ONE_CHECKED_STACK(p, source) \
 369         GC_mark_and_push_stack(p, (ptr_t)(source))
 370 #else
 371 #   define PUSH_ONE_CHECKED_STACK(p, source) \
 372         GC_mark_and_push_stack(p)
 373 #endif
 374
 375 /*
 376  * Push a single value onto mark stack. Mark from the object pointed to by p.
 377  * Invoke FIXUP_POINTER(p) before any further processing.
 378  * P is considered valid even if it is an interior pointer.
 379  * Previously marked objects are not pushed.  Hence we make progress even
 380  * if the mark stack overflows.
 381  */
 382
 383 # if NEED_FIXUP_POINTER
 384     /* Try both the raw version and the fixed up one.   */
 385 #   define GC_PUSH_ONE_STACK(p, source) \
 386       if ((p) >= (ptr_t)GC_least_plausible_heap_addr    \
 387          && (p) < (ptr_t)GC_greatest_plausible_heap_addr) {     \
 388          PUSH_ONE_CHECKED_STACK(p, source);     \
 389       } \
 390       FIXUP_POINTER(p); \
 391       if ((p) >= (ptr_t)GC_least_plausible_heap_addr    \
 392          && (p) < (ptr_t)GC_greatest_plausible_heap_addr) {     \
 393          PUSH_ONE_CHECKED_STACK(p, source);     \
 394       }
 395 # else /* !NEED_FIXUP_POINTER */
 396 #   define GC_PUSH_ONE_STACK(p, source) \
 397       if ((ptr_t)(p) >= (ptr_t)GC_least_plausible_heap_addr     \
 398          && (ptr_t)(p) < (ptr_t)GC_greatest_plausible_heap_addr) {      \
 399          PUSH_ONE_CHECKED_STACK(p, source);     \
 400       }
 401 # endif
 402
 403
 404 /*
 405  * As above, but interior pointer recognition as for
 406  * normal heap pointers.
 407  */
 408 # define GC_PUSH_ONE_HEAP(p,source) \
 409     FIXUP_POINTER(p); \
 410     if ((p) >= (ptr_t)GC_least_plausible_heap_addr      \
 411          && (p) < (ptr_t)GC_greatest_plausible_heap_addr) {     \
 412             GC_mark_stack_top = GC_mark_and_push( \
 413                             (void *)(p), GC_mark_stack_top, \
 414                             GC_mark_stack_limit, (void * *)(source)); \
 415     }
 416
 417 /* Mark starting at mark stack entry top (incl.) down to        */
 418 /* mark stack entry bottom (incl.).  Stop after performing      */
 419 /* about one page worth of work.  Return the new mark stack     */
 420 /* top entry.                                                   */
 421 mse * GC_mark_from(mse * top, mse * bottom, mse *limit);
 422
 423 #define MARK_FROM_MARK_STACK() \
 424         GC_mark_stack_top = GC_mark_from(GC_mark_stack_top, \
 425                                          GC_mark_stack, \
 426                                          GC_mark_stack + GC_mark_stack_size);
 427
 428 /*
 429  * Mark from one finalizable object using the specified
 430  * mark proc. May not mark the object pointed to by
 431  * real_ptr. That is the job of the caller, if appropriate.
 432  * Note that this is called with the mutator running, but
 433  * with us holding the allocation lock.  This is safe only if the
 434  * mutator needs tha allocation lock to reveal hidden pointers.
 435  * FIXME: Why do we need the GC_mark_state test below?
 436  */
 437 # define GC_MARK_FO(real_ptr, mark_proc) \
 438 { \
 439     (*(mark_proc))(real_ptr); \
 440     while (!GC_mark_stack_empty()) MARK_FROM_MARK_STACK(); \
 441     if (GC_mark_state != MS_NONE) { \
 442         GC_set_mark_bit(real_ptr); \
 443         while (!GC_mark_some((ptr_t)0)) {} \
 444     } \
 445 }
 446
 447 extern GC_bool GC_mark_stack_too_small;
 448                                 /* We need a larger mark stack.  May be */
 449                                 /* set by client supplied mark routines.*/
 450
 451 typedef int mark_state_t;       /* Current state of marking, as follows:*/
 452                                 /* Used to remember where we are during */
 453                                 /* concurrent marking.                  */
 454
 455                                 /* We say something is dirty if it was  */
 456                                 /* written since the last time we       */
 457                                 /* retrieved dirty bits.  We say it's   */
 458                                 /* grungy if it was marked dirty in the */
 459                                 /* last set of bits we retrieved.       */
 460
 461                                 /* Invariant I: all roots and marked    */
 462                                 /* objects p are either dirty, or point */
 463                                 /* to objects q that are either marked  */
 464                                 /* or a pointer to q appears in a range */
 465                                 /* on the mark stack.                   */
 466
 467 # define MS_NONE 0              /* No marking in progress. I holds.     */
 468                                 /* Mark stack is empty.                 */
 469
 470 # define MS_PUSH_RESCUERS 1     /* Rescuing objects are currently       */
 471                                 /* being pushed.  I holds, except       */
 472                                 /* that grungy roots may point to       */
 473                                 /* unmarked objects, as may marked      */
 474                                 /* grungy objects above scan_ptr.       */
 475
 476 # define MS_PUSH_UNCOLLECTABLE 2
 477                                 /* I holds, except that marked          */
 478                                 /* uncollectable objects above scan_ptr */
 479                                 /* may point to unmarked objects.       */
 480                                 /* Roots may point to unmarked objects  */
 481
 482 # define MS_ROOTS_PUSHED 3      /* I holds, mark stack may be nonempty  */
 483
 484 # define MS_PARTIALLY_INVALID 4 /* I may not hold, e.g. because of M.S. */
 485                                 /* overflow.  However marked heap       */
 486                                 /* objects below scan_ptr point to      */
 487                                 /* marked or stacked objects.           */
 488
 489 # define MS_INVALID 5           /* I may not hold.                      */
 490
 491 extern mark_state_t GC_mark_state;
 492
 493 #endif  /* GC_PMARK_H */
 494