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::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::const_eval::EvalHint::ExprTypeChecked;
28 use middle::const_eval::eval_const_expr_partial;
30 use middle::def_id::DefId;
31 use trans::{adt, closure, debuginfo, expr, inline, machine};
32 use trans::base::{self, push_ctxt};
33 use trans::collector::{self, TransItem};
34 use trans::common::{self, type_is_sized, ExprOrMethodCall, node_id_substs, C_nil, const_get_elt};
35 use trans::common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty};
36 use trans::common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint};
37 use trans::common::{type_is_fat_ptr, Field, C_vector, C_array, C_null, ExprId, MethodCallKey};
39 use trans::monomorphize;
40 use trans::type_::Type;
43 use middle::subst::Substs;
44 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
45 use middle::ty::adjustment::AdjustUnsafeFnPointer;
46 use middle::ty::{self, Ty};
47 use middle::ty::cast::{CastTy,IntTy};
48 use util::nodemap::NodeMap;
52 use std::ffi::{CStr, CString};
57 use syntax::parse::token;
60 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
62 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit)
64 let _icx = push_ctxt("trans_lit");
65 debug!("const_lit: {:?}", lit);
67 ast::LitByte(b) => C_integral(Type::uint_from_ty(cx, ast::TyU8), b as u64, false),
68 ast::LitChar(i) => C_integral(Type::char(cx), i as u64, false),
69 ast::LitInt(i, ast::SignedIntLit(t, _)) => {
70 C_integral(Type::int_from_ty(cx, t), i, true)
72 ast::LitInt(u, ast::UnsignedIntLit(t)) => {
73 C_integral(Type::uint_from_ty(cx, t), u, false)
75 ast::LitInt(i, ast::UnsuffixedIntLit(_)) => {
76 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
77 match lit_int_ty.sty {
79 C_integral(Type::int_from_ty(cx, t), i as u64, true)
82 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
84 _ => cx.sess().span_bug(lit.span,
85 &format!("integer literal has type {:?} (expected int \
90 ast::LitFloat(ref fs, t) => {
91 C_floating(&fs, Type::float_from_ty(cx, t))
93 ast::LitFloatUnsuffixed(ref fs) => {
94 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
95 match lit_float_ty.sty {
97 C_floating(&fs, Type::float_from_ty(cx, t))
100 cx.sess().span_bug(lit.span,
101 "floating point literal doesn't have the right type");
105 ast::LitBool(b) => C_bool(cx, b),
106 ast::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()),
107 ast::LitByteStr(ref data) => {
108 addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str")
113 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
115 llvm::LLVMConstPointerCast(val, ty.to_ref())
119 fn addr_of_mut(ccx: &CrateContext,
121 align: machine::llalign,
125 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
126 // counter? Also most other uses of gensym in trans.
127 let gsym = token::gensym("_");
128 let name = format!("{}{}", kind, gsym.0);
129 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
130 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
132 llvm::LLVMSetInitializer(gv, cv);
133 llvm::LLVMSetAlignment(gv, align);
134 SetLinkage(gv, InternalLinkage);
135 SetUnnamedAddr(gv, true);
140 pub fn addr_of(ccx: &CrateContext,
142 align: machine::llalign,
145 match ccx.const_globals().borrow().get(&cv) {
148 // Upgrade the alignment in cases where the same constant is used with different
149 // alignment requirements
150 if align > llvm::LLVMGetAlignment(gv) {
151 llvm::LLVMSetAlignment(gv, align);
158 let gv = addr_of_mut(ccx, cv, align, kind);
160 llvm::LLVMSetGlobalConstant(gv, True);
162 ccx.const_globals().borrow_mut().insert(cv, gv);
166 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
167 let v = match cx.const_unsized().borrow().get(&v) {
172 llvm::LLVMGetInitializer(v)
176 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
179 -> (ValueRef, Ty<'tcx>) {
180 match ty.builtin_deref(true, ty::NoPreference) {
182 if type_is_sized(cx.tcx(), mt.ty) {
183 (const_deref_ptr(cx, v), mt.ty)
185 // Derefing a fat pointer does not change the representation,
186 // just the type to the unsized contents.
191 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
197 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
198 node: ExprOrMethodCall,
200 arg_vals: &[ValueRef],
201 param_substs: &'tcx Substs<'tcx>,
202 trueconst: TrueConst) -> Result<ValueRef, ConstEvalFailure> {
203 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
204 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
206 let args = &fn_like.decl().inputs;
207 assert_eq!(args.len(), arg_vals.len());
209 let arg_ids = args.iter().map(|arg| arg.pat.id);
210 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
212 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
213 match fn_like.body().expr {
215 const_expr(ccx, &**expr, substs, Some(&fn_args), trueconst).map(|(res, _)| res)
217 None => Ok(C_nil(ccx)),
221 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
223 ref_expr: &hir::Expr,
224 param_substs: &'tcx Substs<'tcx>)
226 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
228 if def_id.krate != LOCAL_CRATE {
229 ccx.sess().span_bug(ref_expr.span,
230 "cross crate constant could not be inlined");
233 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id), Some(param_substs)) {
234 Some(ref expr) => expr,
236 ccx.sess().span_bug(ref_expr.span, "constant item not found")
241 pub enum ConstEvalFailure {
242 /// in case the const evaluator failed on something that panic at runtime
243 /// as defined in RFC 1229
244 Runtime(ConstEvalErr),
245 // in case we found a true constant
246 Compiletime(ConstEvalErr),
249 impl ConstEvalFailure {
250 fn into_inner(self) -> ConstEvalErr {
256 pub fn description(&self) -> Cow<str> {
258 &Runtime(ref e) => e.description(),
259 &Compiletime(ref e) => e.description(),
264 #[derive(Copy, Clone)]
269 use self::ConstEvalFailure::*;
271 fn get_const_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
273 ref_expr: &hir::Expr,
274 param_substs: &'tcx Substs<'tcx>)
275 -> Result<ValueRef, ConstEvalFailure> {
276 let expr = get_const_expr(ccx, def_id, ref_expr, param_substs);
277 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
278 match get_const_expr_as_global(ccx, expr, ConstQualif::empty(), empty_substs, TrueConst::Yes) {
279 Err(Runtime(err)) => {
280 ccx.tcx().sess.span_err(expr.span, &err.description());
281 Err(Compiletime(err))
287 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
290 param_substs: &'tcx Substs<'tcx>,
291 trueconst: TrueConst)
292 -> Result<ValueRef, ConstEvalFailure> {
293 debug!("get_const_expr_as_global: {:?}", expr.id);
294 // Special-case constants to cache a common global for all uses.
295 if let hir::ExprPath(..) = expr.node {
296 // `def` must be its own statement and cannot be in the `match`
297 // otherwise the `def_map` will be borrowed for the entire match instead
298 // of just to get the `def` value
299 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
301 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
302 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
303 debug!("get_const_expr_as_global ({:?}): found const {:?}",
305 return get_const_val(ccx, def_id, expr, param_substs);
312 let key = (expr.id, param_substs);
313 if let Some(&val) = ccx.const_values().borrow().get(&key) {
316 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
317 &ccx.tcx().expr_ty(expr));
318 let val = if qualif.intersects(ConstQualif::NON_STATIC_BORROWS) {
319 // Avoid autorefs as they would create global instead of stack
320 // references, even when only the latter are correct.
321 try!(const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst))
323 try!(const_expr(ccx, expr, param_substs, None, trueconst)).0
326 // boolean SSA values are i1, but they have to be stored in i8 slots,
327 // otherwise some LLVM optimization passes don't work as expected
329 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
330 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
336 let lvalue = addr_of(ccx, val, type_of::align_of(ccx, ty), "const");
337 ccx.const_values().borrow_mut().insert(key, lvalue);
341 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
343 param_substs: &'tcx Substs<'tcx>,
345 trueconst: TrueConst)
346 -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> {
347 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
348 &cx.tcx().expr_ty(e));
349 let llconst = try!(const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst));
350 let mut llconst = llconst;
351 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
352 &cx.tcx().expr_ty_adjusted(e));
353 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
355 Some(AdjustReifyFnPointer) => {
356 // FIXME(#19925) once fn item types are
357 // zero-sized, we'll need to do something here
359 Some(AdjustUnsafeFnPointer) => {
360 // purely a type-level thing
362 Some(AdjustDerefRef(adj)) => {
364 // Save the last autoderef in case we can avoid it.
365 if adj.autoderefs > 0 {
366 for _ in 0..adj.autoderefs-1 {
367 let (dv, dt) = const_deref(cx, llconst, ty);
373 if adj.autoref.is_some() {
374 if adj.autoderefs == 0 {
375 // Don't copy data to do a deref+ref
376 // (i.e., skip the last auto-deref).
377 llconst = addr_of(cx, llconst, type_of::align_of(cx, ty), "autoref");
378 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
381 let (dv, dt) = const_deref(cx, llconst, ty);
384 // If we derefed a fat pointer then we will have an
385 // open type here. So we need to update the type with
386 // the one returned from const_deref.
390 if let Some(target) = adj.unsize {
391 let target = monomorphize::apply_param_substs(cx.tcx(),
395 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
396 .expect("consts: unsizing got non-pointer type").ty;
397 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
398 // Normally, the source is a thin pointer and we are
399 // adding extra info to make a fat pointer. The exception
400 // is when we are upcasting an existing object fat pointer
401 // to use a different vtable. In that case, we want to
402 // load out the original data pointer so we can repackage
404 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
405 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
410 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
411 .expect("consts: unsizing got non-pointer target type").ty;
412 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
413 let base = ptrcast(base, ptr_ty);
414 let info = base::unsized_info(cx, pointee_ty, unsized_ty,
415 old_info, param_substs);
417 if old_info.is_none() {
418 let prev_const = cx.const_unsized().borrow_mut()
419 .insert(base, llconst);
420 assert!(prev_const.is_none() || prev_const == Some(llconst));
422 assert_eq!(abi::FAT_PTR_ADDR, 0);
423 assert_eq!(abi::FAT_PTR_EXTRA, 1);
424 llconst = C_struct(cx, &[base, info], false);
430 let llty = type_of::sizing_type_of(cx, ety_adjusted);
431 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
432 let tsize = machine::llsize_of_alloc(cx, llty);
434 cx.sess().abort_if_errors();
436 // FIXME these values could use some context
437 llvm::LLVMDumpValue(llconst);
438 llvm::LLVMDumpValue(C_undef(llty));
440 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
444 Ok((llconst, ety_adjusted))
447 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
448 te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
449 // The only kind of unary expression that we check for validity
450 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
451 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
453 // An unfortunate special case: we parse e.g. -128 as a
454 // negation of the literal 128, which means if we're expecting
455 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
456 // 128 will have already overflowed to -128, and so then the
457 // constant evaluator thinks we're trying to negate -128.
459 // Catch this up front by looking for ExprLit directly,
460 // and just accepting it.
461 if let hir::ExprLit(_) = inner_e.node { return Ok(()); }
463 let result = match t.sty {
464 ty::TyInt(int_type) => {
465 let input = match const_to_opt_int(te) {
467 None => return Ok(()),
469 const_int_checked_neg(
470 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
472 ty::TyUint(uint_type) => {
473 let input = match const_to_opt_uint(te) {
475 None => return Ok(()),
477 const_uint_checked_neg(
478 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
482 const_err(cx, e, result, trueconst)
488 fn const_err(cx: &CrateContext,
490 result: Result<ConstVal, ConstEvalErr>,
491 trueconst: TrueConst)
492 -> Result<(), ConstEvalFailure> {
493 match (result, trueconst) {
495 // We do not actually care about a successful result.
498 (Err(err), TrueConst::Yes) => {
499 cx.tcx().sess.span_err(e.span, &err.description());
500 Err(Compiletime(err))
502 (Err(err), TrueConst::No) => {
503 cx.tcx().sess.span_warn(e.span, &err.description());
509 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
510 te1: ValueRef, te2: ValueRef,
511 trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
512 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { unreachable!() };
514 let result = match t.sty {
515 ty::TyInt(int_type) => {
516 let (lhs, rhs) = match (const_to_opt_int(te1),
517 const_to_opt_int(te2)) {
518 (Some(v1), Some(v2)) => (v1, v2),
522 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
524 hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
525 hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
526 hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
527 hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
528 hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
529 hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
530 hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
534 ty::TyUint(uint_type) => {
535 let (lhs, rhs) = match (const_to_opt_uint(te1),
536 const_to_opt_uint(te2)) {
537 (Some(v1), Some(v2)) => (v1, v2),
541 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
543 hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
544 hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
545 hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
546 hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
547 hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
548 hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
549 hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
555 const_err(cx, e, result, trueconst)
558 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
561 param_substs: &'tcx Substs<'tcx>,
563 trueconst: TrueConst)
564 -> Result<ValueRef, ConstEvalFailure>
566 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
571 let map_list = |exprs: &[P<hir::Expr>]| -> Result<Vec<ValueRef>, ConstEvalFailure> {
573 .map(|e| const_expr(cx, &**e, param_substs, fn_args, trueconst).map(|(l, _)| l))
574 .collect::<Vec<Result<ValueRef, ConstEvalFailure>>>()
577 // this dance is necessary to eagerly run const_expr so all errors are reported
579 let _icx = push_ctxt("const_expr");
581 hir::ExprLit(ref lit) => const_lit(cx, e, &**lit),
582 hir::ExprBinary(b, ref e1, ref e2) => {
583 /* Neither type is bottom, and we expect them to be unified
584 * already, so the following is safe. */
585 let (te1, ty) = try!(const_expr(cx, &**e1, param_substs, fn_args, trueconst));
586 debug!("const_expr_unadjusted: te1={}, ty={:?}",
587 cx.tn().val_to_string(te1),
589 assert!(!ty.is_simd());
590 let is_float = ty.is_fp();
591 let signed = ty.is_signed();
593 let (te2, _) = try!(const_expr(cx, &**e2, param_substs, fn_args, trueconst));
595 try!(check_binary_expr_validity(cx, e, ty, te1, te2, trueconst));
597 unsafe { match b.node {
598 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
599 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
601 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
602 hir::BiSub => llvm::LLVMConstSub(te1, te2),
604 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
605 hir::BiMul => llvm::LLVMConstMul(te1, te2),
607 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
608 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
609 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
611 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
612 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
613 hir::BiRem => llvm::LLVMConstURem(te1, te2),
615 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
616 hir::BiOr => llvm::LLVMConstOr(te1, te2),
617 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
618 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
619 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
621 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
622 llvm::LLVMConstShl(te1, te2)
625 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
626 if signed { llvm::LLVMConstAShr(te1, te2) }
627 else { llvm::LLVMConstLShr(te1, te2) }
629 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
631 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
632 ConstFCmp(cmp, te1, te2)
634 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
635 ConstICmp(cmp, te1, te2)
638 } } // unsafe { match b.node {
640 hir::ExprUnary(u, ref inner_e) => {
641 let (te, ty) = try!(const_expr(cx, &**inner_e, param_substs, fn_args, trueconst));
643 try!(check_unary_expr_validity(cx, e, ty, te, trueconst));
645 let is_float = ty.is_fp();
647 hir::UnDeref => const_deref(cx, te, ty).0,
648 hir::UnNot => llvm::LLVMConstNot(te),
649 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
650 hir::UnNeg => llvm::LLVMConstNeg(te),
653 hir::ExprField(ref base, field) => {
654 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
655 let brepr = adt::represent_type(cx, bt);
656 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
657 let ix = vinfo.field_index(field.node);
658 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, ix)
660 hir::ExprTupField(ref base, idx) => {
661 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
662 let brepr = adt::represent_type(cx, bt);
663 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
664 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, idx.node)
666 hir::ExprIndex(ref base, ref index) => {
667 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
668 let iv = match eval_const_expr_partial(cx.tcx(), &index, ExprTypeChecked, None) {
669 Ok(ConstVal::Int(i)) => i as u64,
670 Ok(ConstVal::Uint(u)) => u,
671 _ => cx.sess().span_bug(index.span,
672 "index is not an integer-constant expression")
674 let (arr, len) = match bt.sty {
675 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
676 ty::TySlice(_) | ty::TyStr => {
677 let e1 = const_get_elt(cx, bv, &[0]);
678 (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1]))
680 ty::TyRef(_, mt) => match mt.ty.sty {
681 ty::TyArray(_, u) => {
682 (const_deref_ptr(cx, bv), C_uint(cx, u))
684 _ => cx.sess().span_bug(base.span,
685 &format!("index-expr base must be a vector \
686 or string type, found {:?}",
689 _ => cx.sess().span_bug(base.span,
690 &format!("index-expr base must be a vector \
691 or string type, found {:?}",
695 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
696 let len = match bt.sty {
697 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
707 // FIXME #3170: report this earlier on in the const-eval
708 // pass. Reporting here is a bit late.
709 span_err!(cx.sess(), e.span, E0515,
710 "const index-expr is out of bounds");
711 C_undef(val_ty(arr).element_type())
713 const_get_elt(cx, arr, &[iv as c_uint])
716 hir::ExprCast(ref base, _) => {
718 let llty = type_of::type_of(cx, t_cast);
719 let (v, t_expr) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
720 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
721 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
724 if type_is_fat_ptr(cx.tcx(), t_expr) {
725 // Fat pointer casts.
727 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
728 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
729 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
731 if type_is_fat_ptr(cx.tcx(), t_cast) {
732 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
733 return Ok(C_struct(cx, &[addr, info], false))
739 CastTy::from_ty(t_expr).expect("bad input type for cast"),
740 CastTy::from_ty(t_cast).expect("bad output type for cast"),
742 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
743 let repr = adt::represent_type(cx, t_expr);
744 let discr = adt::const_get_discrim(cx, &*repr, v);
745 let iv = C_integral(cx.int_type(), discr.0, false);
746 let s = adt::is_discr_signed(&*repr) as Bool;
747 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
749 (CastTy::Int(_), CastTy::Int(_)) => {
750 let s = t_expr.is_signed() as Bool;
751 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
753 (CastTy::Int(_), CastTy::Float) => {
754 if t_expr.is_signed() {
755 llvm::LLVMConstSIToFP(v, llty.to_ref())
757 llvm::LLVMConstUIToFP(v, llty.to_ref())
760 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
761 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
762 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
763 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
764 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
767 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
768 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
769 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
770 llvm::LLVMConstPtrToInt(v, llty.to_ref())
773 cx.sess().impossible_case(e.span,
774 "bad combination of types for cast")
776 } } // unsafe { match ( ... ) {
778 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
779 // If this is the address of some static, then we need to return
780 // the actual address of the static itself (short circuit the rest
785 hir::ExprBlock(ref blk) => {
786 if let Some(ref sub) = blk.expr {
795 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
796 if let Some(Def::Static(def_id, _)) = opt_def {
797 common::get_static_val(cx, def_id, ety)
799 // If this isn't the address of a static, then keep going through
800 // normal constant evaluation.
801 let (v, ty) = try!(const_expr(cx, &**sub, param_substs, fn_args, trueconst));
802 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
805 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
806 let (v, ty) = try!(const_expr(cx, &**sub, param_substs, fn_args, trueconst));
807 addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
809 hir::ExprTup(ref es) => {
810 let repr = adt::represent_type(cx, ety);
811 let vals = try!(map_list(&es[..]));
812 adt::trans_const(cx, &*repr, Disr(0), &vals[..])
814 hir::ExprStruct(_, ref fs, ref base_opt) => {
815 let repr = adt::represent_type(cx, ety);
817 let base_val = match *base_opt {
818 Some(ref base) => Some(try!(const_expr(
828 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
829 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
830 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
831 (Some(ref f), _) => {
832 const_expr(cx, &*f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l)
834 (_, Some((bv, _))) => Ok(adt::const_get_field(cx, &*repr, bv, discr, ix)),
835 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
838 .collect::<Vec<Result<_, ConstEvalFailure>>>()
840 .collect::<Result<Vec<_>,ConstEvalFailure>>();
845 adt::trans_const(cx, &*repr, discr, &cs[..])
848 hir::ExprVec(ref es) => {
849 let unit_ty = ety.sequence_element_type(cx.tcx());
850 let llunitty = type_of::type_of(cx, unit_ty);
859 .collect::<Vec<Result<_, ConstEvalFailure>>>()
861 .collect::<Result<Vec<_>, ConstEvalFailure>>();
863 // If the vector contains enums, an LLVM array won't work.
864 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
865 C_struct(cx, &vs[..], false)
867 C_array(llunitty, &vs[..])
870 hir::ExprRepeat(ref elem, ref count) => {
871 let unit_ty = ety.sequence_element_type(cx.tcx());
872 let llunitty = type_of::type_of(cx, unit_ty);
873 let n = cx.tcx().eval_repeat_count(count);
874 let unit_val = try!(const_expr(cx, &**elem, param_substs, fn_args, trueconst)).0;
875 let vs = vec![unit_val; n];
876 if val_ty(unit_val) != llunitty {
877 C_struct(cx, &vs[..], false)
879 C_array(llunitty, &vs[..])
882 hir::ExprPath(..) => {
883 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
885 Def::Local(_, id) => {
886 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
889 cx.sess().span_bug(e.span, "const fn argument not found")
892 Def::Fn(..) | Def::Method(..) => {
893 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
895 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
896 const_deref_ptr(cx, try!(get_const_val(cx, def_id, e, param_substs)))
898 Def::Variant(enum_did, variant_did) => {
899 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
901 ty::VariantKind::Unit => {
902 let repr = adt::represent_type(cx, ety);
903 adt::trans_const(cx, &*repr, Disr::from(vinfo.disr_val), &[])
905 ty::VariantKind::Tuple => {
906 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
908 ty::VariantKind::Struct => {
909 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
914 if let ty::TyBareFn(..) = ety.sty {
916 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
919 C_null(type_of::type_of(cx, ety))
923 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
928 hir::ExprCall(ref callee, ref args) => {
929 let mut callee = &**callee;
931 callee = match callee.node {
932 hir::ExprBlock(ref block) => match block.expr {
933 Some(ref tail) => &**tail,
939 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
940 let arg_vals = try!(map_list(args));
942 Def::Fn(did) | Def::Method(did) => {
954 C_vector(&arg_vals[..])
956 let repr = adt::represent_type(cx, ety);
957 adt::trans_const(cx, &*repr, Disr(0), &arg_vals[..])
960 Def::Variant(enum_did, variant_did) => {
961 let repr = adt::represent_type(cx, ety);
962 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
965 Disr::from(vinfo.disr_val),
968 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
971 hir::ExprMethodCall(_, _, ref args) => {
972 let arg_vals = try!(map_list(args));
973 let method_call = ty::MethodCall::expr(e.id);
974 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
975 try!(const_fn_call(cx, MethodCallKey(method_call),
976 method_did, &arg_vals, param_substs, trueconst))
978 hir::ExprType(ref e, _) => try!(const_expr(cx, &**e, param_substs, fn_args, trueconst)).0,
979 hir::ExprBlock(ref block) => {
981 Some(ref expr) => try!(const_expr(
991 hir::ExprClosure(_, ref decl, ref body) => {
993 ty::TyClosure(def_id, ref substs) => {
994 closure::trans_closure_expr(closure::Dest::Ignore(cx),
1005 &format!("bad type for closure expr: {:?}", ety))
1007 C_null(type_of::type_of(cx, ety))
1009 _ => cx.sess().span_bug(e.span,
1010 "bad constant expression type in consts::const_expr"),
1014 pub fn trans_static(ccx: &CrateContext,
1018 attrs: &[ast::Attribute])
1019 -> Result<ValueRef, ConstEvalErr> {
1021 if collector::collecting_debug_information(ccx) {
1022 ccx.record_translation_item_as_generated(TransItem::Static(id));
1026 let _icx = push_ctxt("trans_static");
1027 let g = base::get_item_val(ccx, id);
1029 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
1030 let (v, _) = try!(const_expr(
1036 ).map_err(|e| e.into_inner()));
1038 // boolean SSA values are i1, but they have to be stored in i8 slots,
1039 // otherwise some LLVM optimization passes don't work as expected
1040 let mut val_llty = llvm::LLVMTypeOf(v);
1041 let v = if val_llty == Type::i1(ccx).to_ref() {
1042 val_llty = Type::i8(ccx).to_ref();
1043 llvm::LLVMConstZExt(v, val_llty)
1048 let ty = ccx.tcx().node_id_to_type(id);
1049 let llty = type_of::type_of(ccx, ty);
1050 let g = if val_llty == llty.to_ref() {
1053 // If we created the global with the wrong type,
1054 // correct the type.
1055 let empty_string = CString::new("").unwrap();
1056 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
1057 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
1058 llvm::LLVMSetValueName(g, empty_string.as_ptr());
1059 let new_g = llvm::LLVMGetOrInsertGlobal(
1060 ccx.llmod(), name_string.as_ptr(), val_llty);
1061 // To avoid breaking any invariants, we leave around the old
1062 // global for the moment; we'll replace all references to it
1063 // with the new global later. (See base::trans_crate.)
1064 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
1067 llvm::LLVMSetAlignment(g, type_of::align_of(ccx, ty));
1068 llvm::LLVMSetInitializer(g, v);
1070 // As an optimization, all shared statics which do not have interior
1071 // mutability are placed into read-only memory.
1072 if m != hir::MutMutable {
1073 let tcontents = ty.type_contents(ccx.tcx());
1074 if !tcontents.interior_unsafe() {
1075 llvm::LLVMSetGlobalConstant(g, llvm::True);
1079 debuginfo::create_global_var_metadata(ccx, id, g);
1081 if attr::contains_name(attrs,
1083 llvm::set_thread_local(g, true);