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1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
4 //
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
10
11
12 use back::abi;
13 use llvm;
14 use llvm::{ConstFCmp, ConstICmp, SetLinkage, SetUnnamedAddr};
15 use llvm::{InternalLinkage, ValueRef, Bool, True};
16 use middle::const_qualif::ConstQualif;
17 use middle::cstore::LOCAL_CRATE;
18 use middle::const_eval::{self, ConstVal, ConstEvalErr};
19 use middle::const_eval::{const_int_checked_neg, const_uint_checked_neg};
20 use middle::const_eval::{const_int_checked_add, const_uint_checked_add};
21 use middle::const_eval::{const_int_checked_sub, const_uint_checked_sub};
22 use middle::const_eval::{const_int_checked_mul, const_uint_checked_mul};
23 use middle::const_eval::{const_int_checked_div, const_uint_checked_div};
24 use middle::const_eval::{const_int_checked_rem, const_uint_checked_rem};
25 use middle::const_eval::{const_int_checked_shl, const_uint_checked_shl};
26 use middle::const_eval::{const_int_checked_shr, const_uint_checked_shr};
27 use middle::def::Def;
28 use middle::def_id::DefId;
29 use trans::{adt, closure, debuginfo, expr, inline, machine};
30 use trans::base::{self, push_ctxt};
31 use trans::collector::{self, TransItem};
32 use trans::common::{self, type_is_sized, ExprOrMethodCall, node_id_substs, C_nil, const_get_elt};
33 use trans::common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty};
34 use trans::common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint};
35 use trans::common::{type_is_fat_ptr, Field, C_vector, C_array, C_null, ExprId, MethodCallKey};
36 use trans::declare;
37 use trans::monomorphize;
38 use trans::type_::Type;
39 use trans::type_of;
40 use trans::Disr;
41 use middle::subst::Substs;
42 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
43 use middle::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer};
44 use middle::ty::{self, Ty};
45 use middle::ty::cast::{CastTy,IntTy};
46 use util::nodemap::NodeMap;
47
48 use rustc_front::hir;
49
50 use std::ffi::{CStr, CString};
51 use std::borrow::Cow;
52 use libc::c_uint;
53 use syntax::ast::{self, LitKind};
54 use syntax::attr;
55 use syntax::parse::token;
56 use syntax::ptr::P;
57
58 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
59
60 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit)
61 -> ValueRef {
62 let _icx = push_ctxt("trans_lit");
63 debug!("const_lit: {:?}", lit);
64 match lit.node {
65 LitKind::Byte(b) => C_integral(Type::uint_from_ty(cx, ast::UintTy::U8), b as u64, false),
66 LitKind::Char(i) => C_integral(Type::char(cx), i as u64, false),
67 LitKind::Int(i, ast::LitIntType::Signed(t)) => {
68 C_integral(Type::int_from_ty(cx, t), i, true)
69 }
70 LitKind::Int(u, ast::LitIntType::Unsigned(t)) => {
71 C_integral(Type::uint_from_ty(cx, t), u, false)
72 }
73 LitKind::Int(i, ast::LitIntType::Unsuffixed) => {
74 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
75 match lit_int_ty.sty {
76 ty::TyInt(t) => {
77 C_integral(Type::int_from_ty(cx, t), i as u64, true)
78 }
79 ty::TyUint(t) => {
80 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
81 }
82 _ => cx.sess().span_bug(lit.span,
83 &format!("integer literal has type {:?} (expected int \
84 or usize)",
85 lit_int_ty))
86 }
87 }
88 LitKind::Float(ref fs, t) => {
89 C_floating(&fs, Type::float_from_ty(cx, t))
90 }
91 LitKind::FloatUnsuffixed(ref fs) => {
92 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
93 match lit_float_ty.sty {
94 ty::TyFloat(t) => {
95 C_floating(&fs, Type::float_from_ty(cx, t))
96 }
97 _ => {
98 cx.sess().span_bug(lit.span,
99 "floating point literal doesn't have the right type");
100 }
101 }
102 }
103 LitKind::Bool(b) => C_bool(cx, b),
104 LitKind::Str(ref s, _) => C_str_slice(cx, (*s).clone()),
105 LitKind::ByteStr(ref data) => {
106 addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str")
107 }
108 }
109 }
110
111 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
112 unsafe {
113 llvm::LLVMConstPointerCast(val, ty.to_ref())
114 }
115 }
116
117 fn addr_of_mut(ccx: &CrateContext,
118 cv: ValueRef,
119 align: machine::llalign,
120 kind: &str)
121 -> ValueRef {
122 unsafe {
123 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
124 // counter? Also most other uses of gensym in trans.
125 let gsym = token::gensym("_");
126 let name = format!("{}{}", kind, gsym.0);
127 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
128 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
129 });
130 llvm::LLVMSetInitializer(gv, cv);
131 llvm::LLVMSetAlignment(gv, align);
132 SetLinkage(gv, InternalLinkage);
133 SetUnnamedAddr(gv, true);
134 gv
135 }
136 }
137
138 pub fn addr_of(ccx: &CrateContext,
139 cv: ValueRef,
140 align: machine::llalign,
141 kind: &str)
142 -> ValueRef {
143 match ccx.const_globals().borrow().get(&cv) {
144 Some(&gv) => {
145 unsafe {
146 // Upgrade the alignment in cases where the same constant is used with different
147 // alignment requirements
148 if align > llvm::LLVMGetAlignment(gv) {
149 llvm::LLVMSetAlignment(gv, align);
150 }
151 }
152 return gv;
153 }
154 None => {}
155 }
156 let gv = addr_of_mut(ccx, cv, align, kind);
157 unsafe {
158 llvm::LLVMSetGlobalConstant(gv, True);
159 }
160 ccx.const_globals().borrow_mut().insert(cv, gv);
161 gv
162 }
163
164 /// Deref a constant pointer
165 fn load_const(cx: &CrateContext, v: ValueRef, t: Ty) -> ValueRef {
166 let v = match cx.const_unsized().borrow().get(&v) {
167 Some(&v) => v,
168 None => v
169 };
170 let d = unsafe { llvm::LLVMGetInitializer(v) };
171 if t.is_bool() {
172 unsafe { llvm::LLVMConstTrunc(d, Type::i1(cx).to_ref()) }
173 } else {
174 d
175 }
176 }
177
178 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
179 v: ValueRef,
180 ty: Ty<'tcx>)
181 -> (ValueRef, Ty<'tcx>) {
182 match ty.builtin_deref(true, ty::NoPreference) {
183 Some(mt) => {
184 if type_is_sized(cx.tcx(), mt.ty) {
185 (load_const(cx, v, mt.ty), mt.ty)
186 } else {
187 // Derefing a fat pointer does not change the representation,
188 // just the type to the unsized contents.
189 (v, mt.ty)
190 }
191 }
192 None => {
193 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
194 ty))
195 }
196 }
197 }
198
199 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
200 node: ExprOrMethodCall,
201 def_id: DefId,
202 arg_vals: &[ValueRef],
203 param_substs: &'tcx Substs<'tcx>,
204 trueconst: TrueConst) -> Result<ValueRef, ConstEvalFailure> {
205 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
206 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
207
208 let args = &fn_like.decl().inputs;
209 assert_eq!(args.len(), arg_vals.len());
210
211 let arg_ids = args.iter().map(|arg| arg.pat.id);
212 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
213
214 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
215 match fn_like.body().expr {
216 Some(ref expr) => {
217 const_expr(ccx, &expr, substs, Some(&fn_args), trueconst).map(|(res, _)| res)
218 },
219 None => Ok(C_nil(ccx)),
220 }
221 }
222
223 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
224 def_id: DefId,
225 ref_expr: &hir::Expr,
226 param_substs: &'tcx Substs<'tcx>)
227 -> &'tcx hir::Expr {
228 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
229
230 if def_id.krate != LOCAL_CRATE {
231 ccx.sess().span_bug(ref_expr.span,
232 "cross crate constant could not be inlined");
233 }
234
235 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id), Some(param_substs)) {
236 Some(ref expr) => expr,
237 None => {
238 ccx.sess().span_bug(ref_expr.span, "constant item not found")
239 }
240 }
241 }
242
243 pub enum ConstEvalFailure {
244 /// in case the const evaluator failed on something that panic at runtime
245 /// as defined in RFC 1229
246 Runtime(ConstEvalErr),
247 // in case we found a true constant
248 Compiletime(ConstEvalErr),
249 }
250
251 impl ConstEvalFailure {
252 fn into_inner(self) -> ConstEvalErr {
253 match self {
254 Runtime(e) => e,
255 Compiletime(e) => e,
256 }
257 }
258 pub fn description(&self) -> Cow<str> {
259 match self {
260 &Runtime(ref e) => e.description(),
261 &Compiletime(ref e) => e.description(),
262 }
263 }
264 }
265
266 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
267 pub enum TrueConst {
268 Yes, No
269 }
270
271 use self::ConstEvalFailure::*;
272
273 fn get_const_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
274 def_id: DefId,
275 ref_expr: &hir::Expr,
276 param_substs: &'tcx Substs<'tcx>)
277 -> Result<ValueRef, ConstEvalFailure> {
278 let expr = get_const_expr(ccx, def_id, ref_expr, param_substs);
279 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
280 match get_const_expr_as_global(ccx, expr, ConstQualif::empty(), empty_substs, TrueConst::Yes) {
281 Err(Runtime(err)) => {
282 ccx.tcx().sess.span_err(expr.span, &err.description());
283 Err(Compiletime(err))
284 },
285 other => other,
286 }
287 }
288
289 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
290 expr: &hir::Expr,
291 qualif: ConstQualif,
292 param_substs: &'tcx Substs<'tcx>,
293 trueconst: TrueConst)
294 -> Result<ValueRef, ConstEvalFailure> {
295 debug!("get_const_expr_as_global: {:?}", expr.id);
296 // Special-case constants to cache a common global for all uses.
297 if let hir::ExprPath(..) = expr.node {
298 // `def` must be its own statement and cannot be in the `match`
299 // otherwise the `def_map` will be borrowed for the entire match instead
300 // of just to get the `def` value
301 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
302 match def {
303 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
304 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
305 debug!("get_const_expr_as_global ({:?}): found const {:?}",
306 expr.id, def_id);
307 return get_const_val(ccx, def_id, expr, param_substs);
308 }
309 },
310 _ => {},
311 }
312 }
313
314 let key = (expr.id, param_substs);
315 if let Some(&val) = ccx.const_values().borrow().get(&key) {
316 return Ok(val);
317 }
318 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
319 &ccx.tcx().expr_ty(expr));
320 let val = if qualif.intersects(ConstQualif::NON_STATIC_BORROWS) {
321 // Avoid autorefs as they would create global instead of stack
322 // references, even when only the latter are correct.
323 try!(const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst))
324 } else {
325 try!(const_expr(ccx, expr, param_substs, None, trueconst)).0
326 };
327
328 // boolean SSA values are i1, but they have to be stored in i8 slots,
329 // otherwise some LLVM optimization passes don't work as expected
330 let val = unsafe {
331 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
332 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
333 } else {
334 val
335 }
336 };
337
338 let lvalue = addr_of(ccx, val, type_of::align_of(ccx, ty), "const");
339 ccx.const_values().borrow_mut().insert(key, lvalue);
340 Ok(lvalue)
341 }
342
343 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
344 e: &hir::Expr,
345 param_substs: &'tcx Substs<'tcx>,
346 fn_args: FnArgMap,
347 trueconst: TrueConst)
348 -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> {
349 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
350 &cx.tcx().expr_ty(e));
351 let llconst = try!(const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst));
352 let mut llconst = llconst;
353 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
354 &cx.tcx().expr_ty_adjusted(e));
355 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
356 match opt_adj {
357 Some(AdjustReifyFnPointer) => {
358 // FIXME(#19925) once fn item types are
359 // zero-sized, we'll need to do something here
360 }
361 Some(AdjustUnsafeFnPointer) | Some(AdjustMutToConstPointer) => {
362 // purely a type-level thing
363 }
364 Some(AdjustDerefRef(adj)) => {
365 let mut ty = ety;
366 // Save the last autoderef in case we can avoid it.
367 if adj.autoderefs > 0 {
368 for _ in 0..adj.autoderefs-1 {
369 let (dv, dt) = const_deref(cx, llconst, ty);
370 llconst = dv;
371 ty = dt;
372 }
373 }
374
375 if adj.autoref.is_some() {
376 if adj.autoderefs == 0 {
377 // Don't copy data to do a deref+ref
378 // (i.e., skip the last auto-deref).
379 llconst = addr_of(cx, llconst, type_of::align_of(cx, ty), "autoref");
380 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
381 }
382 } else {
383 let (dv, dt) = const_deref(cx, llconst, ty);
384 llconst = dv;
385
386 // If we derefed a fat pointer then we will have an
387 // open type here. So we need to update the type with
388 // the one returned from const_deref.
389 ety_adjusted = dt;
390 }
391
392 if let Some(target) = adj.unsize {
393 let target = monomorphize::apply_param_substs(cx.tcx(),
394 param_substs,
395 &target);
396
397 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
398 .expect("consts: unsizing got non-pointer type").ty;
399 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
400 // Normally, the source is a thin pointer and we are
401 // adding extra info to make a fat pointer. The exception
402 // is when we are upcasting an existing object fat pointer
403 // to use a different vtable. In that case, we want to
404 // load out the original data pointer so we can repackage
405 // it.
406 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
407 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
408 } else {
409 (llconst, None)
410 };
411
412 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
413 .expect("consts: unsizing got non-pointer target type").ty;
414 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
415 let base = ptrcast(base, ptr_ty);
416 let info = base::unsized_info(cx, pointee_ty, unsized_ty,
417 old_info, param_substs);
418
419 if old_info.is_none() {
420 let prev_const = cx.const_unsized().borrow_mut()
421 .insert(base, llconst);
422 assert!(prev_const.is_none() || prev_const == Some(llconst));
423 }
424 assert_eq!(abi::FAT_PTR_ADDR, 0);
425 assert_eq!(abi::FAT_PTR_EXTRA, 1);
426 llconst = C_struct(cx, &[base, info], false);
427 }
428 }
429 None => {}
430 };
431
432 let llty = type_of::sizing_type_of(cx, ety_adjusted);
433 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
434 let tsize = machine::llsize_of_alloc(cx, llty);
435 if csize != tsize {
436 cx.sess().abort_if_errors();
437 unsafe {
438 // FIXME these values could use some context
439 llvm::LLVMDumpValue(llconst);
440 llvm::LLVMDumpValue(C_undef(llty));
441 }
442 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
443 e, ety_adjusted,
444 csize, tsize));
445 }
446 Ok((llconst, ety_adjusted))
447 }
448
449 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
450 te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
451 // The only kind of unary expression that we check for validity
452 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
453 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
454
455 // An unfortunate special case: we parse e.g. -128 as a
456 // negation of the literal 128, which means if we're expecting
457 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
458 // 128 will have already overflowed to -128, and so then the
459 // constant evaluator thinks we're trying to negate -128.
460 //
461 // Catch this up front by looking for ExprLit directly,
462 // and just accepting it.
463 if let hir::ExprLit(_) = inner_e.node { return Ok(()); }
464
465 let result = match t.sty {
466 ty::TyInt(int_type) => {
467 let input = match const_to_opt_int(te) {
468 Some(v) => v,
469 None => return Ok(()),
470 };
471 const_int_checked_neg(
472 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
473 }
474 ty::TyUint(uint_type) => {
475 let input = match const_to_opt_uint(te) {
476 Some(v) => v,
477 None => return Ok(()),
478 };
479 const_uint_checked_neg(
480 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
481 }
482 _ => return Ok(()),
483 };
484 const_err(cx, e, result, trueconst)
485 } else {
486 Ok(())
487 }
488 }
489
490 fn const_err(cx: &CrateContext,
491 e: &hir::Expr,
492 result: Result<ConstVal, ConstEvalErr>,
493 trueconst: TrueConst)
494 -> Result<(), ConstEvalFailure> {
495 match (result, trueconst) {
496 (Ok(_), _) => {
497 // We do not actually care about a successful result.
498 Ok(())
499 },
500 (Err(err), TrueConst::Yes) => {
501 cx.tcx().sess.span_err(e.span, &err.description());
502 Err(Compiletime(err))
503 },
504 (Err(err), TrueConst::No) => {
505 cx.tcx().sess.span_warn(e.span, &err.description());
506 Err(Runtime(err))
507 },
508 }
509 }
510
511 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
512 te1: ValueRef, te2: ValueRef,
513 trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
514 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { unreachable!() };
515
516 let result = match t.sty {
517 ty::TyInt(int_type) => {
518 let (lhs, rhs) = match (const_to_opt_int(te1),
519 const_to_opt_int(te2)) {
520 (Some(v1), Some(v2)) => (v1, v2),
521 _ => return Ok(()),
522 };
523
524 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
525 match b.node {
526 hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
527 hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
528 hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
529 hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
530 hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
531 hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
532 hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
533 _ => return Ok(()),
534 }
535 }
536 ty::TyUint(uint_type) => {
537 let (lhs, rhs) = match (const_to_opt_uint(te1),
538 const_to_opt_uint(te2)) {
539 (Some(v1), Some(v2)) => (v1, v2),
540 _ => return Ok(()),
541 };
542
543 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
544 match b.node {
545 hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
546 hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
547 hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
548 hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
549 hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
550 hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
551 hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
552 _ => return Ok(()),
553 }
554 }
555 _ => return Ok(()),
556 };
557 const_err(cx, e, result, trueconst)
558 }
559
560 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
561 e: &hir::Expr,
562 ety: Ty<'tcx>,
563 param_substs: &'tcx Substs<'tcx>,
564 fn_args: FnArgMap,
565 trueconst: TrueConst)
566 -> Result<ValueRef, ConstEvalFailure>
567 {
568 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
569 e,
570 ety,
571 param_substs);
572
573 let map_list = |exprs: &[P<hir::Expr>]| -> Result<Vec<ValueRef>, ConstEvalFailure> {
574 exprs.iter()
575 .map(|e| const_expr(cx, &e, param_substs, fn_args, trueconst).map(|(l, _)| l))
576 .collect::<Vec<Result<ValueRef, ConstEvalFailure>>>()
577 .into_iter()
578 .collect()
579 // this dance is necessary to eagerly run const_expr so all errors are reported
580 };
581 let _icx = push_ctxt("const_expr");
582 Ok(match e.node {
583 hir::ExprLit(ref lit) => const_lit(cx, e, &lit),
584 hir::ExprBinary(b, ref e1, ref e2) => {
585 /* Neither type is bottom, and we expect them to be unified
586 * already, so the following is safe. */
587 let (te1, ty) = try!(const_expr(cx, &e1, param_substs, fn_args, trueconst));
588 debug!("const_expr_unadjusted: te1={}, ty={:?}",
589 cx.tn().val_to_string(te1),
590 ty);
591 assert!(!ty.is_simd());
592 let is_float = ty.is_fp();
593 let signed = ty.is_signed();
594
595 let (te2, ty2) = try!(const_expr(cx, &e2, param_substs, fn_args, trueconst));
596 debug!("const_expr_unadjusted: te2={}, ty={:?}",
597 cx.tn().val_to_string(te2),
598 ty2);
599
600 try!(check_binary_expr_validity(cx, e, ty, te1, te2, trueconst));
601
602 unsafe { match b.node {
603 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
604 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
605
606 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
607 hir::BiSub => llvm::LLVMConstSub(te1, te2),
608
609 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
610 hir::BiMul => llvm::LLVMConstMul(te1, te2),
611
612 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
613 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
614 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
615
616 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
617 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
618 hir::BiRem => llvm::LLVMConstURem(te1, te2),
619
620 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
621 hir::BiOr => llvm::LLVMConstOr(te1, te2),
622 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
623 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
624 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
625 hir::BiShl => {
626 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
627 llvm::LLVMConstShl(te1, te2)
628 },
629 hir::BiShr => {
630 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
631 if signed { llvm::LLVMConstAShr(te1, te2) }
632 else { llvm::LLVMConstLShr(te1, te2) }
633 },
634 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
635 if is_float {
636 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
637 ConstFCmp(cmp, te1, te2)
638 } else {
639 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
640 ConstICmp(cmp, te1, te2)
641 }
642 },
643 } } // unsafe { match b.node {
644 },
645 hir::ExprUnary(u, ref inner_e) => {
646 let (te, ty) = try!(const_expr(cx, &inner_e, param_substs, fn_args, trueconst));
647
648 try!(check_unary_expr_validity(cx, e, ty, te, trueconst));
649
650 let is_float = ty.is_fp();
651 unsafe { match u {
652 hir::UnDeref => const_deref(cx, te, ty).0,
653 hir::UnNot => llvm::LLVMConstNot(te),
654 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
655 hir::UnNeg => llvm::LLVMConstNeg(te),
656 } }
657 },
658 hir::ExprField(ref base, field) => {
659 let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
660 let brepr = adt::represent_type(cx, bt);
661 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
662 let ix = vinfo.field_index(field.node);
663 adt::const_get_field(cx, &brepr, bv, vinfo.discr, ix)
664 },
665 hir::ExprTupField(ref base, idx) => {
666 let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
667 let brepr = adt::represent_type(cx, bt);
668 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
669 adt::const_get_field(cx, &brepr, bv, vinfo.discr, idx.node)
670 },
671 hir::ExprIndex(ref base, ref index) => {
672 let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
673 let iv = try!(const_expr(cx, &index, param_substs, fn_args, TrueConst::Yes)).0;
674 let iv = if let Some(iv) = const_to_opt_uint(iv) {
675 iv
676 } else {
677 cx.sess().span_bug(index.span, "index is not an integer-constant expression");
678 };
679 let (arr, len) = match bt.sty {
680 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
681 ty::TySlice(..) | ty::TyStr => {
682 let e1 = const_get_elt(cx, bv, &[0]);
683 (load_const(cx, e1, bt), const_get_elt(cx, bv, &[1]))
684 },
685 ty::TyRef(_, mt) => match mt.ty.sty {
686 ty::TyArray(_, u) => {
687 (load_const(cx, bv, mt.ty), C_uint(cx, u))
688 },
689 _ => cx.sess().span_bug(base.span,
690 &format!("index-expr base must be a vector \
691 or string type, found {:?}",
692 bt)),
693 },
694 _ => cx.sess().span_bug(base.span,
695 &format!("index-expr base must be a vector \
696 or string type, found {:?}",
697 bt)),
698 };
699
700 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
701 let len = match bt.sty {
702 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
703 ty::TyStr => {
704 assert!(len > 0);
705 len - 1
706 },
707 _ => len,
708 },
709 _ => len,
710 };
711 if iv >= len {
712 // FIXME #3170: report this earlier on in the const-eval
713 // pass. Reporting here is a bit late.
714 span_err!(cx.sess(), e.span, E0515,
715 "const index-expr is out of bounds");
716 C_undef(val_ty(arr).element_type())
717 } else {
718 const_get_elt(cx, arr, &[iv as c_uint])
719 }
720 },
721 hir::ExprCast(ref base, _) => {
722 let t_cast = ety;
723 let llty = type_of::type_of(cx, t_cast);
724 let (v, t_expr) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
725 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
726 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
727 return Ok(v);
728 }
729 if type_is_fat_ptr(cx.tcx(), t_expr) {
730 // Fat pointer casts.
731 let t_cast_inner =
732 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
733 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
734 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
735 ptr_ty);
736 if type_is_fat_ptr(cx.tcx(), t_cast) {
737 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
738 return Ok(C_struct(cx, &[addr, info], false))
739 } else {
740 return Ok(addr);
741 }
742 }
743 unsafe { match (
744 CastTy::from_ty(t_expr).expect("bad input type for cast"),
745 CastTy::from_ty(t_cast).expect("bad output type for cast"),
746 ) {
747 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
748 let repr = adt::represent_type(cx, t_expr);
749 let discr = adt::const_get_discrim(cx, &repr, v);
750 let iv = C_integral(cx.int_type(), discr.0, false);
751 let s = adt::is_discr_signed(&repr) as Bool;
752 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
753 },
754 (CastTy::Int(_), CastTy::Int(_)) => {
755 let s = t_expr.is_signed() as Bool;
756 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
757 },
758 (CastTy::Int(_), CastTy::Float) => {
759 if t_expr.is_signed() {
760 llvm::LLVMConstSIToFP(v, llty.to_ref())
761 } else {
762 llvm::LLVMConstUIToFP(v, llty.to_ref())
763 }
764 },
765 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
766 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
767 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
768 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
769 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
770 ptrcast(v, llty)
771 },
772 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
773 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
774 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
775 llvm::LLVMConstPtrToInt(v, llty.to_ref())
776 },
777 _ => {
778 cx.sess().impossible_case(e.span,
779 "bad combination of types for cast")
780 },
781 } } // unsafe { match ( ... ) {
782 },
783 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
784 // If this is the address of some static, then we need to return
785 // the actual address of the static itself (short circuit the rest
786 // of const eval).
787 let mut cur = sub;
788 loop {
789 match cur.node {
790 hir::ExprBlock(ref blk) => {
791 if let Some(ref sub) = blk.expr {
792 cur = sub;
793 } else {
794 break;
795 }
796 },
797 _ => break,
798 }
799 }
800 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
801 if let Some(Def::Static(def_id, _)) = opt_def {
802 common::get_static_val(cx, def_id, ety)
803 } else {
804 // If this isn't the address of a static, then keep going through
805 // normal constant evaluation.
806 let (v, ty) = try!(const_expr(cx, &sub, param_substs, fn_args, trueconst));
807 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
808 }
809 },
810 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
811 let (v, ty) = try!(const_expr(cx, &sub, param_substs, fn_args, trueconst));
812 addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
813 },
814 hir::ExprTup(ref es) => {
815 let repr = adt::represent_type(cx, ety);
816 let vals = try!(map_list(&es[..]));
817 adt::trans_const(cx, &repr, Disr(0), &vals[..])
818 },
819 hir::ExprStruct(_, ref fs, ref base_opt) => {
820 let repr = adt::represent_type(cx, ety);
821
822 let base_val = match *base_opt {
823 Some(ref base) => Some(try!(const_expr(
824 cx,
825 &base,
826 param_substs,
827 fn_args,
828 trueconst,
829 ))),
830 None => None
831 };
832
833 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
834 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
835 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
836 (Some(ref f), _) => {
837 const_expr(cx, &f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l)
838 },
839 (_, Some((bv, _))) => Ok(adt::const_get_field(cx, &repr, bv, discr, ix)),
840 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
841 }
842 })
843 .collect::<Vec<Result<_, ConstEvalFailure>>>()
844 .into_iter()
845 .collect::<Result<Vec<_>,ConstEvalFailure>>();
846 let cs = try!(cs);
847 if ety.is_simd() {
848 C_vector(&cs[..])
849 } else {
850 adt::trans_const(cx, &repr, discr, &cs[..])
851 }
852 },
853 hir::ExprVec(ref es) => {
854 let unit_ty = ety.sequence_element_type(cx.tcx());
855 let llunitty = type_of::type_of(cx, unit_ty);
856 let vs = es.iter()
857 .map(|e| const_expr(
858 cx,
859 &e,
860 param_substs,
861 fn_args,
862 trueconst,
863 ).map(|(l, _)| l))
864 .collect::<Vec<Result<_, ConstEvalFailure>>>()
865 .into_iter()
866 .collect::<Result<Vec<_>, ConstEvalFailure>>();
867 let vs = try!(vs);
868 // If the vector contains enums, an LLVM array won't work.
869 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
870 C_struct(cx, &vs[..], false)
871 } else {
872 C_array(llunitty, &vs[..])
873 }
874 },
875 hir::ExprRepeat(ref elem, ref count) => {
876 let unit_ty = ety.sequence_element_type(cx.tcx());
877 let llunitty = type_of::type_of(cx, unit_ty);
878 let n = cx.tcx().eval_repeat_count(count);
879 let unit_val = try!(const_expr(cx, &elem, param_substs, fn_args, trueconst)).0;
880 let vs = vec![unit_val; n];
881 if val_ty(unit_val) != llunitty {
882 C_struct(cx, &vs[..], false)
883 } else {
884 C_array(llunitty, &vs[..])
885 }
886 },
887 hir::ExprPath(..) => {
888 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
889 match def {
890 Def::Local(_, id) => {
891 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
892 val
893 } else {
894 cx.sess().span_bug(e.span, "const fn argument not found")
895 }
896 }
897 Def::Fn(..) | Def::Method(..) => {
898 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
899 }
900 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
901 load_const(cx, try!(get_const_val(cx, def_id, e, param_substs)),
902 ety)
903 }
904 Def::Variant(enum_did, variant_did) => {
905 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
906 match vinfo.kind() {
907 ty::VariantKind::Unit => {
908 let repr = adt::represent_type(cx, ety);
909 adt::trans_const(cx, &repr, Disr::from(vinfo.disr_val), &[])
910 }
911 ty::VariantKind::Tuple => {
912 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
913 }
914 ty::VariantKind::Struct => {
915 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
916 }
917 }
918 }
919 Def::Struct(..) => {
920 if let ty::TyBareFn(..) = ety.sty {
921 // Tuple struct.
922 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
923 } else {
924 // Unit struct.
925 C_null(type_of::type_of(cx, ety))
926 }
927 }
928 _ => {
929 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
930 or variant def")
931 }
932 }
933 },
934 hir::ExprCall(ref callee, ref args) => {
935 let mut callee = &**callee;
936 loop {
937 callee = match callee.node {
938 hir::ExprBlock(ref block) => match block.expr {
939 Some(ref tail) => &tail,
940 None => break,
941 },
942 _ => break,
943 };
944 }
945 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
946 let arg_vals = try!(map_list(args));
947 match def {
948 Def::Fn(did) | Def::Method(did) => {
949 try!(const_fn_call(
950 cx,
951 ExprId(callee.id),
952 did,
953 &arg_vals,
954 param_substs,
955 trueconst,
956 ))
957 }
958 Def::Struct(..) => {
959 if ety.is_simd() {
960 C_vector(&arg_vals[..])
961 } else {
962 let repr = adt::represent_type(cx, ety);
963 adt::trans_const(cx, &repr, Disr(0), &arg_vals[..])
964 }
965 }
966 Def::Variant(enum_did, variant_did) => {
967 let repr = adt::represent_type(cx, ety);
968 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
969 adt::trans_const(cx,
970 &repr,
971 Disr::from(vinfo.disr_val),
972 &arg_vals[..])
973 }
974 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
975 }
976 },
977 hir::ExprMethodCall(_, _, ref args) => {
978 let arg_vals = try!(map_list(args));
979 let method_call = ty::MethodCall::expr(e.id);
980 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
981 try!(const_fn_call(cx, MethodCallKey(method_call),
982 method_did, &arg_vals, param_substs, trueconst))
983 },
984 hir::ExprType(ref e, _) => try!(const_expr(cx, &e, param_substs, fn_args, trueconst)).0,
985 hir::ExprBlock(ref block) => {
986 match block.expr {
987 Some(ref expr) => try!(const_expr(
988 cx,
989 &expr,
990 param_substs,
991 fn_args,
992 trueconst,
993 )).0,
994 None => C_nil(cx),
995 }
996 },
997 hir::ExprClosure(_, ref decl, ref body) => {
998 match ety.sty {
999 ty::TyClosure(def_id, ref substs) => {
1000 closure::trans_closure_expr(closure::Dest::Ignore(cx),
1001 decl,
1002 body,
1003 e.id,
1004 def_id,
1005 substs,
1006 &e.attrs);
1007 }
1008 _ =>
1009 cx.sess().span_bug(
1010 e.span,
1011 &format!("bad type for closure expr: {:?}", ety))
1012 }
1013 C_null(type_of::type_of(cx, ety))
1014 },
1015 _ => cx.sess().span_bug(e.span,
1016 "bad constant expression type in consts::const_expr"),
1017 })
1018 }
1019
1020 pub fn trans_static(ccx: &CrateContext,
1021 m: hir::Mutability,
1022 expr: &hir::Expr,
1023 id: ast::NodeId,
1024 attrs: &[ast::Attribute])
1025 -> Result<ValueRef, ConstEvalErr> {
1026
1027 if collector::collecting_debug_information(ccx) {
1028 ccx.record_translation_item_as_generated(TransItem::Static(id));
1029 }
1030
1031 unsafe {
1032 let _icx = push_ctxt("trans_static");
1033 let g = base::get_item_val(ccx, id);
1034
1035 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
1036 let (v, _) = try!(const_expr(
1037 ccx,
1038 expr,
1039 empty_substs,
1040 None,
1041 TrueConst::Yes,
1042 ).map_err(|e| e.into_inner()));
1043
1044 // boolean SSA values are i1, but they have to be stored in i8 slots,
1045 // otherwise some LLVM optimization passes don't work as expected
1046 let mut val_llty = llvm::LLVMTypeOf(v);
1047 let v = if val_llty == Type::i1(ccx).to_ref() {
1048 val_llty = Type::i8(ccx).to_ref();
1049 llvm::LLVMConstZExt(v, val_llty)
1050 } else {
1051 v
1052 };
1053
1054 let ty = ccx.tcx().node_id_to_type(id);
1055 let llty = type_of::type_of(ccx, ty);
1056 let g = if val_llty == llty.to_ref() {
1057 g
1058 } else {
1059 // If we created the global with the wrong type,
1060 // correct the type.
1061 let empty_string = CString::new("").unwrap();
1062 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
1063 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
1064 llvm::LLVMSetValueName(g, empty_string.as_ptr());
1065 let new_g = llvm::LLVMGetOrInsertGlobal(
1066 ccx.llmod(), name_string.as_ptr(), val_llty);
1067 // To avoid breaking any invariants, we leave around the old
1068 // global for the moment; we'll replace all references to it
1069 // with the new global later. (See base::trans_crate.)
1070 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
1071 new_g
1072 };
1073 llvm::LLVMSetAlignment(g, type_of::align_of(ccx, ty));
1074 llvm::LLVMSetInitializer(g, v);
1075
1076 // As an optimization, all shared statics which do not have interior
1077 // mutability are placed into read-only memory.
1078 if m != hir::MutMutable {
1079 let tcontents = ty.type_contents(ccx.tcx());
1080 if !tcontents.interior_unsafe() {
1081 llvm::LLVMSetGlobalConstant(g, llvm::True);
1082 }
1083 }
1084
1085 debuginfo::create_global_var_metadata(ccx, id, g);
1086
1087 if attr::contains_name(attrs,
1088 "thread_local") {
1089 llvm::set_thread_local(g, true);
1090 }
1091 Ok(g)
1092 }
1093 }