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.
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.
14 use llvm::{ConstFCmp, ConstICmp, SetLinkage, SetUnnamedAddr};
15 use llvm::{InternalLinkage, ValueRef, Bool, True};
16 use middle::{check_const, def};
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::const_eval::EvalHint::ExprTypeChecked;
28 use middle::const_eval::eval_const_expr_partial;
29 use middle::def_id::DefId;
30 use trans::{adt, closure, debuginfo, expr, inline, machine};
31 use trans::base::{self, push_ctxt};
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};
37 use trans::monomorphize;
38 use trans::type_::Type;
40 use middle::subst::Substs;
41 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
42 use middle::ty::adjustment::AdjustUnsafeFnPointer;
43 use middle::ty::{self, Ty};
44 use middle::ty::cast::{CastTy,IntTy};
45 use util::nodemap::NodeMap;
49 use std::ffi::{CStr, CString};
54 use syntax::parse::token;
57 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
59 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit)
61 let _icx = push_ctxt("trans_lit");
62 debug!("const_lit: {:?}", lit);
64 ast::LitByte(b) => C_integral(Type::uint_from_ty(cx, ast::TyU8), b as u64, false),
65 ast::LitChar(i) => C_integral(Type::char(cx), i as u64, false),
66 ast::LitInt(i, ast::SignedIntLit(t, _)) => {
67 C_integral(Type::int_from_ty(cx, t), i, true)
69 ast::LitInt(u, ast::UnsignedIntLit(t)) => {
70 C_integral(Type::uint_from_ty(cx, t), u, false)
72 ast::LitInt(i, ast::UnsuffixedIntLit(_)) => {
73 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
74 match lit_int_ty.sty {
76 C_integral(Type::int_from_ty(cx, t), i as u64, true)
79 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
81 _ => cx.sess().span_bug(lit.span,
82 &format!("integer literal has type {:?} (expected int \
87 ast::LitFloat(ref fs, t) => {
88 C_floating(&fs, Type::float_from_ty(cx, t))
90 ast::LitFloatUnsuffixed(ref fs) => {
91 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
92 match lit_float_ty.sty {
94 C_floating(&fs, Type::float_from_ty(cx, t))
97 cx.sess().span_bug(lit.span,
98 "floating point literal doesn't have the right type");
102 ast::LitBool(b) => C_bool(cx, b),
103 ast::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()),
104 ast::LitByteStr(ref data) => {
105 addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str")
110 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
112 llvm::LLVMConstPointerCast(val, ty.to_ref())
116 fn addr_of_mut(ccx: &CrateContext,
118 align: machine::llalign,
122 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
123 // counter? Also most other uses of gensym in trans.
124 let gsym = token::gensym("_");
125 let name = format!("{}{}", kind, gsym.0);
126 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
127 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
129 llvm::LLVMSetInitializer(gv, cv);
130 llvm::LLVMSetAlignment(gv, align);
131 SetLinkage(gv, InternalLinkage);
132 SetUnnamedAddr(gv, true);
137 pub fn addr_of(ccx: &CrateContext,
139 align: machine::llalign,
142 match ccx.const_globals().borrow().get(&cv) {
145 // Upgrade the alignment in cases where the same constant is used with different
146 // alignment requirements
147 if align > llvm::LLVMGetAlignment(gv) {
148 llvm::LLVMSetAlignment(gv, align);
155 let gv = addr_of_mut(ccx, cv, align, kind);
157 llvm::LLVMSetGlobalConstant(gv, True);
159 ccx.const_globals().borrow_mut().insert(cv, gv);
163 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
164 let v = match cx.const_unsized().borrow().get(&v) {
169 llvm::LLVMGetInitializer(v)
173 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
176 -> (ValueRef, Ty<'tcx>) {
177 match ty.builtin_deref(true, ty::NoPreference) {
179 if type_is_sized(cx.tcx(), mt.ty) {
180 (const_deref_ptr(cx, v), mt.ty)
182 // Derefing a fat pointer does not change the representation,
183 // just the type to the unsized contents.
188 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
194 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
195 node: ExprOrMethodCall,
197 arg_vals: &[ValueRef],
198 param_substs: &'tcx Substs<'tcx>,
199 trueconst: TrueConst) -> Result<ValueRef, ConstEvalFailure> {
200 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
201 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
203 let args = &fn_like.decl().inputs;
204 assert_eq!(args.len(), arg_vals.len());
206 let arg_ids = args.iter().map(|arg| arg.pat.id);
207 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
209 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
210 match fn_like.body().expr {
212 const_expr(ccx, &**expr, substs, Some(&fn_args), trueconst).map(|(res, _)| res)
214 None => Ok(C_nil(ccx)),
218 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
220 ref_expr: &hir::Expr)
222 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
224 if def_id.krate != LOCAL_CRATE {
225 ccx.sess().span_bug(ref_expr.span,
226 "cross crate constant could not be inlined");
229 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id)) {
230 Some(ref expr) => expr,
232 ccx.sess().span_bug(ref_expr.span, "constant item not found")
237 pub enum ConstEvalFailure {
238 /// in case the const evaluator failed on something that panic at runtime
239 /// as defined in RFC 1229
240 Runtime(ConstEvalErr),
241 // in case we found a true constant
242 Compiletime(ConstEvalErr),
245 impl ConstEvalFailure {
246 fn into_inner(self) -> ConstEvalErr {
252 pub fn description(&self) -> Cow<str> {
254 &Runtime(ref e) => e.description(),
255 &Compiletime(ref e) => e.description(),
260 #[derive(Copy, Clone)]
265 use self::ConstEvalFailure::*;
267 fn get_const_val(ccx: &CrateContext,
269 ref_expr: &hir::Expr) -> Result<ValueRef, ConstEvalFailure> {
270 let expr = get_const_expr(ccx, def_id, ref_expr);
271 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
272 match get_const_expr_as_global(ccx, expr, check_const::ConstQualif::empty(),
273 empty_substs, TrueConst::Yes) {
274 Err(Runtime(err)) => {
275 ccx.tcx().sess.span_err(expr.span, &err.description());
276 Err(Compiletime(err))
282 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
284 qualif: check_const::ConstQualif,
285 param_substs: &'tcx Substs<'tcx>,
286 trueconst: TrueConst)
287 -> Result<ValueRef, ConstEvalFailure> {
288 debug!("get_const_expr_as_global: {:?}", expr.id);
289 // Special-case constants to cache a common global for all uses.
290 if let hir::ExprPath(..) = expr.node {
291 // `def` must be its own statement and cannot be in the `match`
292 // otherwise the `def_map` will be borrowed for the entire match instead
293 // of just to get the `def` value
294 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
296 def::DefConst(def_id) | def::DefAssociatedConst(def_id) => {
297 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
298 debug!("get_const_expr_as_global ({:?}): found const {:?}",
300 return get_const_val(ccx, def_id, expr);
307 let key = (expr.id, param_substs);
308 if let Some(&val) = ccx.const_values().borrow().get(&key) {
311 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
312 &ccx.tcx().expr_ty(expr));
313 let val = if qualif.intersects(check_const::ConstQualif::NON_STATIC_BORROWS) {
314 // Avoid autorefs as they would create global instead of stack
315 // references, even when only the latter are correct.
316 try!(const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst))
318 try!(const_expr(ccx, expr, param_substs, None, trueconst)).0
321 // boolean SSA values are i1, but they have to be stored in i8 slots,
322 // otherwise some LLVM optimization passes don't work as expected
324 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
325 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
331 let lvalue = addr_of(ccx, val, type_of::align_of(ccx, ty), "const");
332 ccx.const_values().borrow_mut().insert(key, lvalue);
336 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
338 param_substs: &'tcx Substs<'tcx>,
340 trueconst: TrueConst)
341 -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> {
342 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
343 &cx.tcx().expr_ty(e));
344 let llconst = try!(const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst));
345 let mut llconst = llconst;
346 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
347 &cx.tcx().expr_ty_adjusted(e));
348 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
350 Some(AdjustReifyFnPointer) => {
351 // FIXME(#19925) once fn item types are
352 // zero-sized, we'll need to do something here
354 Some(AdjustUnsafeFnPointer) => {
355 // purely a type-level thing
357 Some(AdjustDerefRef(adj)) => {
359 // Save the last autoderef in case we can avoid it.
360 if adj.autoderefs > 0 {
361 for _ in 0..adj.autoderefs-1 {
362 let (dv, dt) = const_deref(cx, llconst, ty);
368 if adj.autoref.is_some() {
369 if adj.autoderefs == 0 {
370 // Don't copy data to do a deref+ref
371 // (i.e., skip the last auto-deref).
372 llconst = addr_of(cx, llconst, type_of::align_of(cx, ty), "autoref");
373 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
376 let (dv, dt) = const_deref(cx, llconst, ty);
379 // If we derefed a fat pointer then we will have an
380 // open type here. So we need to update the type with
381 // the one returned from const_deref.
385 if let Some(target) = adj.unsize {
386 let target = monomorphize::apply_param_substs(cx.tcx(),
390 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
391 .expect("consts: unsizing got non-pointer type").ty;
392 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
393 // Normally, the source is a thin pointer and we are
394 // adding extra info to make a fat pointer. The exception
395 // is when we are upcasting an existing object fat pointer
396 // to use a different vtable. In that case, we want to
397 // load out the original data pointer so we can repackage
399 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
400 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
405 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
406 .expect("consts: unsizing got non-pointer target type").ty;
407 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
408 let base = ptrcast(base, ptr_ty);
409 let info = base::unsized_info(cx, pointee_ty, unsized_ty,
410 old_info, param_substs);
412 if old_info.is_none() {
413 let prev_const = cx.const_unsized().borrow_mut()
414 .insert(base, llconst);
415 assert!(prev_const.is_none() || prev_const == Some(llconst));
417 assert_eq!(abi::FAT_PTR_ADDR, 0);
418 assert_eq!(abi::FAT_PTR_EXTRA, 1);
419 llconst = C_struct(cx, &[base, info], false);
425 let llty = type_of::sizing_type_of(cx, ety_adjusted);
426 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
427 let tsize = machine::llsize_of_alloc(cx, llty);
429 cx.sess().abort_if_errors();
431 // FIXME these values could use some context
432 llvm::LLVMDumpValue(llconst);
433 llvm::LLVMDumpValue(C_undef(llty));
435 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
439 Ok((llconst, ety_adjusted))
442 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
443 te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
444 // The only kind of unary expression that we check for validity
445 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
446 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
448 // An unfortunate special case: we parse e.g. -128 as a
449 // negation of the literal 128, which means if we're expecting
450 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
451 // 128 will have already overflowed to -128, and so then the
452 // constant evaluator thinks we're trying to negate -128.
454 // Catch this up front by looking for ExprLit directly,
455 // and just accepting it.
456 if let hir::ExprLit(_) = inner_e.node { return Ok(()); }
458 let result = match t.sty {
459 ty::TyInt(int_type) => {
460 let input = match const_to_opt_int(te) {
462 None => return Ok(()),
464 const_int_checked_neg(
465 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
467 ty::TyUint(uint_type) => {
468 let input = match const_to_opt_uint(te) {
470 None => return Ok(()),
472 const_uint_checked_neg(
473 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
477 const_err(cx, e, result, trueconst)
483 fn const_err(cx: &CrateContext,
485 result: Result<ConstVal, ConstEvalErr>,
486 trueconst: TrueConst)
487 -> Result<(), ConstEvalFailure> {
488 match (result, trueconst) {
490 // We do not actually care about a successful result.
493 (Err(err), TrueConst::Yes) => {
494 cx.tcx().sess.span_err(e.span, &err.description());
495 Err(Compiletime(err))
497 (Err(err), TrueConst::No) => {
498 cx.tcx().sess.span_warn(e.span, &err.description());
504 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
505 te1: ValueRef, te2: ValueRef,
506 trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
507 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { unreachable!() };
509 let result = match t.sty {
510 ty::TyInt(int_type) => {
511 let (lhs, rhs) = match (const_to_opt_int(te1),
512 const_to_opt_int(te2)) {
513 (Some(v1), Some(v2)) => (v1, v2),
517 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
519 hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
520 hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
521 hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
522 hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
523 hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
524 hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
525 hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
529 ty::TyUint(uint_type) => {
530 let (lhs, rhs) = match (const_to_opt_uint(te1),
531 const_to_opt_uint(te2)) {
532 (Some(v1), Some(v2)) => (v1, v2),
536 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
538 hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
539 hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
540 hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
541 hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
542 hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
543 hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
544 hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
550 const_err(cx, e, result, trueconst)
553 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
556 param_substs: &'tcx Substs<'tcx>,
558 trueconst: TrueConst)
559 -> Result<ValueRef, ConstEvalFailure>
561 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
566 let map_list = |exprs: &[P<hir::Expr>]| -> Result<Vec<ValueRef>, ConstEvalFailure> {
568 .map(|e| const_expr(cx, &**e, param_substs, fn_args, trueconst).map(|(l, _)| l))
569 .collect::<Vec<Result<ValueRef, ConstEvalFailure>>>()
572 // this dance is necessary to eagerly run const_expr so all errors are reported
574 let _icx = push_ctxt("const_expr");
576 hir::ExprLit(ref lit) => const_lit(cx, e, &**lit),
577 hir::ExprBinary(b, ref e1, ref e2) => {
578 /* Neither type is bottom, and we expect them to be unified
579 * already, so the following is safe. */
580 let (te1, ty) = try!(const_expr(cx, &**e1, param_substs, fn_args, trueconst));
581 debug!("const_expr_unadjusted: te1={}, ty={:?}",
582 cx.tn().val_to_string(te1),
584 assert!(!ty.is_simd());
585 let is_float = ty.is_fp();
586 let signed = ty.is_signed();
588 let (te2, _) = try!(const_expr(cx, &**e2, param_substs, fn_args, trueconst));
590 try!(check_binary_expr_validity(cx, e, ty, te1, te2, trueconst));
592 unsafe { match b.node {
593 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
594 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
596 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
597 hir::BiSub => llvm::LLVMConstSub(te1, te2),
599 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
600 hir::BiMul => llvm::LLVMConstMul(te1, te2),
602 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
603 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
604 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
606 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
607 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
608 hir::BiRem => llvm::LLVMConstURem(te1, te2),
610 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
611 hir::BiOr => llvm::LLVMConstOr(te1, te2),
612 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
613 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
614 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
616 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
617 llvm::LLVMConstShl(te1, te2)
620 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
621 if signed { llvm::LLVMConstAShr(te1, te2) }
622 else { llvm::LLVMConstLShr(te1, te2) }
624 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
626 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
627 ConstFCmp(cmp, te1, te2)
629 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
630 ConstICmp(cmp, te1, te2)
633 } } // unsafe { match b.node {
635 hir::ExprUnary(u, ref inner_e) => {
636 let (te, ty) = try!(const_expr(cx, &**inner_e, param_substs, fn_args, trueconst));
638 try!(check_unary_expr_validity(cx, e, ty, te, trueconst));
640 let is_float = ty.is_fp();
642 hir::UnDeref => const_deref(cx, te, ty).0,
643 hir::UnNot => llvm::LLVMConstNot(te),
644 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
645 hir::UnNeg => llvm::LLVMConstNeg(te),
648 hir::ExprField(ref base, field) => {
649 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
650 let brepr = adt::represent_type(cx, bt);
651 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
652 let ix = vinfo.field_index(field.node);
653 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, ix)
655 hir::ExprTupField(ref base, idx) => {
656 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
657 let brepr = adt::represent_type(cx, bt);
658 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
659 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, idx.node)
661 hir::ExprIndex(ref base, ref index) => {
662 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
663 let iv = match eval_const_expr_partial(cx.tcx(), &index, ExprTypeChecked, None) {
664 Ok(ConstVal::Int(i)) => i as u64,
665 Ok(ConstVal::Uint(u)) => u,
666 _ => cx.sess().span_bug(index.span,
667 "index is not an integer-constant expression")
669 let (arr, len) = match bt.sty {
670 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
671 ty::TySlice(_) | ty::TyStr => {
672 let e1 = const_get_elt(cx, bv, &[0]);
673 (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1]))
675 ty::TyRef(_, mt) => match mt.ty.sty {
676 ty::TyArray(_, u) => {
677 (const_deref_ptr(cx, bv), C_uint(cx, u))
679 _ => cx.sess().span_bug(base.span,
680 &format!("index-expr base must be a vector \
681 or string type, found {:?}",
684 _ => cx.sess().span_bug(base.span,
685 &format!("index-expr base must be a vector \
686 or string type, found {:?}",
690 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
691 let len = match bt.sty {
692 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
702 // FIXME #3170: report this earlier on in the const-eval
703 // pass. Reporting here is a bit late.
704 span_err!(cx.sess(), e.span, E0515,
705 "const index-expr is out of bounds");
706 C_undef(val_ty(arr).element_type())
708 const_get_elt(cx, arr, &[iv as c_uint])
711 hir::ExprCast(ref base, _) => {
713 let llty = type_of::type_of(cx, t_cast);
714 let (v, t_expr) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
715 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
716 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
719 if type_is_fat_ptr(cx.tcx(), t_expr) {
720 // Fat pointer casts.
722 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
723 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
724 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
726 if type_is_fat_ptr(cx.tcx(), t_cast) {
727 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
728 return Ok(C_struct(cx, &[addr, info], false))
734 CastTy::from_ty(t_expr).expect("bad input type for cast"),
735 CastTy::from_ty(t_cast).expect("bad output type for cast"),
737 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
738 let repr = adt::represent_type(cx, t_expr);
739 let discr = adt::const_get_discrim(cx, &*repr, v);
740 let iv = C_integral(cx.int_type(), discr, false);
741 let s = adt::is_discr_signed(&*repr) as Bool;
742 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
744 (CastTy::Int(_), CastTy::Int(_)) => {
745 let s = t_expr.is_signed() as Bool;
746 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
748 (CastTy::Int(_), CastTy::Float) => {
749 if t_expr.is_signed() {
750 llvm::LLVMConstSIToFP(v, llty.to_ref())
752 llvm::LLVMConstUIToFP(v, llty.to_ref())
755 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
756 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
757 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
758 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
759 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
762 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
763 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
764 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
765 llvm::LLVMConstPtrToInt(v, llty.to_ref())
768 cx.sess().impossible_case(e.span,
769 "bad combination of types for cast")
771 } } // unsafe { match ( ... ) {
773 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
774 // If this is the address of some static, then we need to return
775 // the actual address of the static itself (short circuit the rest
780 hir::ExprBlock(ref blk) => {
781 if let Some(ref sub) = blk.expr {
790 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
791 if let Some(def::DefStatic(def_id, _)) = opt_def {
792 common::get_static_val(cx, def_id, ety)
794 // If this isn't the address of a static, then keep going through
795 // normal constant evaluation.
796 let (v, ty) = try!(const_expr(cx, &**sub, param_substs, fn_args, trueconst));
797 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
800 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
801 let (v, ty) = try!(const_expr(cx, &**sub, param_substs, fn_args, trueconst));
802 addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
804 hir::ExprTup(ref es) => {
805 let repr = adt::represent_type(cx, ety);
806 let vals = try!(map_list(&es[..]));
807 adt::trans_const(cx, &*repr, 0, &vals[..])
809 hir::ExprStruct(_, ref fs, ref base_opt) => {
810 let repr = adt::represent_type(cx, ety);
812 let base_val = match *base_opt {
813 Some(ref base) => Some(try!(const_expr(
823 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
824 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
825 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
826 (Some(ref f), _) => {
827 const_expr(cx, &*f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l)
829 (_, Some((bv, _))) => Ok(adt::const_get_field(cx, &*repr, bv, discr, ix)),
830 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
833 .collect::<Vec<Result<_, ConstEvalFailure>>>()
835 .collect::<Result<Vec<_>,ConstEvalFailure>>();
840 adt::trans_const(cx, &*repr, discr, &cs[..])
843 hir::ExprVec(ref es) => {
844 let unit_ty = ety.sequence_element_type(cx.tcx());
845 let llunitty = type_of::type_of(cx, unit_ty);
854 .collect::<Vec<Result<_, ConstEvalFailure>>>()
856 .collect::<Result<Vec<_>, ConstEvalFailure>>();
858 // If the vector contains enums, an LLVM array won't work.
859 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
860 C_struct(cx, &vs[..], false)
862 C_array(llunitty, &vs[..])
865 hir::ExprRepeat(ref elem, ref count) => {
866 let unit_ty = ety.sequence_element_type(cx.tcx());
867 let llunitty = type_of::type_of(cx, unit_ty);
868 let n = cx.tcx().eval_repeat_count(count);
869 let unit_val = try!(const_expr(cx, &**elem, param_substs, fn_args, trueconst)).0;
870 let vs = vec![unit_val; n];
871 if val_ty(unit_val) != llunitty {
872 C_struct(cx, &vs[..], false)
874 C_array(llunitty, &vs[..])
877 hir::ExprPath(..) => {
878 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
880 def::DefLocal(_, id) => {
881 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
884 cx.sess().span_bug(e.span, "const fn argument not found")
887 def::DefFn(..) | def::DefMethod(..) => {
888 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
890 def::DefConst(def_id) | def::DefAssociatedConst(def_id) => {
891 const_deref_ptr(cx, try!(get_const_val(cx, def_id, e)))
893 def::DefVariant(enum_did, variant_did, _) => {
894 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
896 ty::VariantKind::Unit => {
897 let repr = adt::represent_type(cx, ety);
898 adt::trans_const(cx, &*repr, vinfo.disr_val, &[])
900 ty::VariantKind::Tuple => {
901 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
903 ty::VariantKind::Struct => {
904 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
908 def::DefStruct(_) => {
909 if let ty::TyBareFn(..) = ety.sty {
911 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
914 C_null(type_of::type_of(cx, ety))
918 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
923 hir::ExprCall(ref callee, ref args) => {
924 let mut callee = &**callee;
926 callee = match callee.node {
927 hir::ExprBlock(ref block) => match block.expr {
928 Some(ref tail) => &**tail,
934 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
935 let arg_vals = try!(map_list(args));
937 def::DefFn(did, _) | def::DefMethod(did) => {
947 def::DefStruct(_) => {
949 C_vector(&arg_vals[..])
951 let repr = adt::represent_type(cx, ety);
952 adt::trans_const(cx, &*repr, 0, &arg_vals[..])
955 def::DefVariant(enum_did, variant_did, _) => {
956 let repr = adt::represent_type(cx, ety);
957 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
963 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
966 hir::ExprMethodCall(_, _, ref args) => {
967 let arg_vals = try!(map_list(args));
968 let method_call = ty::MethodCall::expr(e.id);
969 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
970 try!(const_fn_call(cx, MethodCallKey(method_call),
971 method_did, &arg_vals, param_substs, trueconst))
973 hir::ExprBlock(ref block) => {
975 Some(ref expr) => try!(const_expr(
985 hir::ExprClosure(_, ref decl, ref body) => {
987 ty::TyClosure(def_id, ref substs) => {
988 closure::trans_closure_expr(closure::Dest::Ignore(cx), decl,
989 body, e.id, def_id, substs);
994 &format!("bad type for closure expr: {:?}", ety))
996 C_null(type_of::type_of(cx, ety))
998 _ => cx.sess().span_bug(e.span,
999 "bad constant expression type in consts::const_expr"),
1003 pub fn trans_static(ccx: &CrateContext,
1007 attrs: &Vec<ast::Attribute>)
1008 -> Result<ValueRef, ConstEvalErr> {
1010 let _icx = push_ctxt("trans_static");
1011 let g = base::get_item_val(ccx, id);
1013 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
1014 let (v, _) = try!(const_expr(
1020 ).map_err(|e| e.into_inner()));
1022 // boolean SSA values are i1, but they have to be stored in i8 slots,
1023 // otherwise some LLVM optimization passes don't work as expected
1024 let mut val_llty = llvm::LLVMTypeOf(v);
1025 let v = if val_llty == Type::i1(ccx).to_ref() {
1026 val_llty = Type::i8(ccx).to_ref();
1027 llvm::LLVMConstZExt(v, val_llty)
1032 let ty = ccx.tcx().node_id_to_type(id);
1033 let llty = type_of::type_of(ccx, ty);
1034 let g = if val_llty == llty.to_ref() {
1037 // If we created the global with the wrong type,
1038 // correct the type.
1039 let empty_string = CString::new("").unwrap();
1040 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
1041 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
1042 llvm::LLVMSetValueName(g, empty_string.as_ptr());
1043 let new_g = llvm::LLVMGetOrInsertGlobal(
1044 ccx.llmod(), name_string.as_ptr(), val_llty);
1045 // To avoid breaking any invariants, we leave around the old
1046 // global for the moment; we'll replace all references to it
1047 // with the new global later. (See base::trans_crate.)
1048 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
1051 llvm::LLVMSetAlignment(g, type_of::align_of(ccx, ty));
1052 llvm::LLVMSetInitializer(g, v);
1054 // As an optimization, all shared statics which do not have interior
1055 // mutability are placed into read-only memory.
1056 if m != hir::MutMutable {
1057 let tcontents = ty.type_contents(ccx.tcx());
1058 if !tcontents.interior_unsafe() {
1059 llvm::LLVMSetGlobalConstant(g, llvm::True);
1063 debuginfo::create_global_var_metadata(ccx, id, g);
1065 if attr::contains_name(attrs,
1067 llvm::set_thread_local(g, true);