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.
13 use llvm::{SetUnnamedAddr};
14 use llvm::{InternalLinkage, ValueRef, Bool, True};
15 use middle::const_qualif::ConstQualif;
16 use rustc_const_eval::{ConstEvalErr, lookup_const_fn_by_id, lookup_const_by_id, ErrKind};
17 use rustc_const_eval::{eval_length, report_const_eval_err, note_const_eval_err};
18 use rustc::hir::def::Def;
19 use rustc::hir::def_id::DefId;
20 use rustc::hir::map as hir_map;
21 use {abi, adt, closure, debuginfo, expr, machine};
22 use base::{self, push_ctxt};
24 use trans_item::TransItem;
25 use common::{type_is_sized, C_nil, const_get_elt};
26 use common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty};
27 use common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint};
28 use common::{type_is_fat_ptr, Field, C_vector, C_array, C_null};
29 use datum::{Datum, Lvalue};
31 use monomorphize::{self, Instance};
36 use rustc::ty::subst::Substs;
37 use rustc::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
38 use rustc::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer};
39 use rustc::ty::{self, Ty, TyCtxt};
40 use rustc::ty::cast::{CastTy,IntTy};
41 use util::nodemap::NodeMap;
42 use rustc_const_math::{ConstInt, ConstUsize, ConstIsize};
46 use std::ffi::{CStr, CString};
48 use syntax::ast::{self, LitKind};
49 use syntax::attr::{self, AttrMetaMethods};
50 use syntax::parse::token;
54 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
56 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit)
58 let _icx = push_ctxt("trans_lit");
59 debug!("const_lit: {:?}", lit);
61 LitKind::Byte(b) => C_integral(Type::uint_from_ty(cx, ast::UintTy::U8), b as u64, false),
62 LitKind::Char(i) => C_integral(Type::char(cx), i as u64, false),
63 LitKind::Int(i, ast::LitIntType::Signed(t)) => {
64 C_integral(Type::int_from_ty(cx, t), i, true)
66 LitKind::Int(u, ast::LitIntType::Unsigned(t)) => {
67 C_integral(Type::uint_from_ty(cx, t), u, false)
69 LitKind::Int(i, ast::LitIntType::Unsuffixed) => {
70 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
71 match lit_int_ty.sty {
73 C_integral(Type::int_from_ty(cx, t), i as u64, true)
76 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
78 _ => span_bug!(lit.span,
79 "integer literal has type {:?} (expected int \
84 LitKind::Float(ref fs, t) => {
85 C_floating(&fs, Type::float_from_ty(cx, t))
87 LitKind::FloatUnsuffixed(ref fs) => {
88 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
89 match lit_float_ty.sty {
91 C_floating(&fs, Type::float_from_ty(cx, t))
95 "floating point literal doesn't have the right type");
99 LitKind::Bool(b) => C_bool(cx, b),
100 LitKind::Str(ref s, _) => C_str_slice(cx, (*s).clone()),
101 LitKind::ByteStr(ref data) => {
102 addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str")
107 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
109 llvm::LLVMConstPointerCast(val, ty.to_ref())
113 pub fn addr_of_mut(ccx: &CrateContext,
115 align: machine::llalign,
119 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
120 // counter? Also most other uses of gensym in trans.
121 let gsym = token::gensym("_");
122 let name = format!("{}{}", kind, gsym.0);
123 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
124 bug!("symbol `{}` is already defined", name);
126 llvm::LLVMSetInitializer(gv, cv);
127 llvm::LLVMSetAlignment(gv, align);
128 llvm::LLVMSetLinkage(gv, InternalLinkage);
129 SetUnnamedAddr(gv, true);
134 pub fn addr_of(ccx: &CrateContext,
136 align: machine::llalign,
139 if let Some(&gv) = ccx.const_globals().borrow().get(&cv) {
141 // Upgrade the alignment in cases where the same constant is used with different
142 // alignment requirements
143 if align > llvm::LLVMGetAlignment(gv) {
144 llvm::LLVMSetAlignment(gv, align);
149 let gv = addr_of_mut(ccx, cv, align, kind);
151 llvm::LLVMSetGlobalConstant(gv, True);
153 ccx.const_globals().borrow_mut().insert(cv, gv);
157 /// Deref a constant pointer
158 pub fn load_const(cx: &CrateContext, v: ValueRef, t: Ty) -> ValueRef {
159 let v = match cx.const_unsized().borrow().get(&v) {
163 let d = unsafe { llvm::LLVMGetInitializer(v) };
164 if !d.is_null() && t.is_bool() {
165 unsafe { llvm::LLVMConstTrunc(d, Type::i1(cx).to_ref()) }
171 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
174 -> (ValueRef, Ty<'tcx>) {
175 match ty.builtin_deref(true, ty::NoPreference) {
177 if type_is_sized(cx.tcx(), mt.ty) {
178 (load_const(cx, v, mt.ty), mt.ty)
180 // Derefing a fat pointer does not change the representation,
181 // just the type to the unsized contents.
186 bug!("unexpected dereferenceable type {:?}", ty)
191 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
193 substs: &'tcx Substs<'tcx>,
194 arg_vals: &[ValueRef],
195 param_substs: &'tcx Substs<'tcx>,
196 trueconst: TrueConst) -> Result<ValueRef, ConstEvalFailure> {
197 let fn_like = lookup_const_fn_by_id(ccx.tcx(), def_id);
198 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
200 let body = match fn_like.body().expr {
201 Some(ref expr) => expr,
202 None => return Ok(C_nil(ccx))
205 let args = &fn_like.decl().inputs;
206 assert_eq!(args.len(), arg_vals.len());
208 let arg_ids = args.iter().map(|arg| arg.pat.id);
209 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
211 let substs = ccx.tcx().mk_substs(substs.clone().erase_regions());
212 let substs = monomorphize::apply_param_substs(ccx.tcx(),
216 const_expr(ccx, body, substs, Some(&fn_args), trueconst).map(|(res, _)| res)
219 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
221 ref_expr: &hir::Expr,
222 param_substs: &'tcx Substs<'tcx>)
224 let substs = ccx.tcx().node_id_item_substs(ref_expr.id).substs;
225 let substs = ccx.tcx().mk_substs(substs.clone().erase_regions());
226 let substs = monomorphize::apply_param_substs(ccx.tcx(),
229 match lookup_const_by_id(ccx.tcx(), def_id, Some(substs)) {
230 Some((ref expr, _ty)) => expr,
232 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 {
253 pub fn as_inner(&self) -> &ConstEvalErr {
255 &Runtime(ref e) => e,
256 &Compiletime(ref e) => e,
261 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
266 use self::ConstEvalFailure::*;
268 fn get_const_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
270 ref_expr: &hir::Expr,
271 param_substs: &'tcx Substs<'tcx>)
272 -> Result<ValueRef, ConstEvalFailure> {
273 let expr = get_const_expr(ccx, def_id, ref_expr, param_substs);
274 let empty_substs = ccx.tcx().mk_substs(Substs::empty());
275 match get_const_expr_as_global(ccx, expr, ConstQualif::empty(), empty_substs, TrueConst::Yes) {
276 Err(Runtime(err)) => {
277 report_const_eval_err(ccx.tcx(), &err, expr.span, "expression").emit();
278 Err(Compiletime(err))
284 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
287 param_substs: &'tcx Substs<'tcx>,
288 trueconst: TrueConst)
289 -> Result<ValueRef, ConstEvalFailure> {
290 debug!("get_const_expr_as_global: {:?}", expr.id);
291 // Special-case constants to cache a common global for all uses.
292 if let hir::ExprPath(..) = expr.node {
293 // `def` must be its own statement and cannot be in the `match`
294 // otherwise the `def_map` will be borrowed for the entire match instead
295 // of just to get the `def` value
296 match ccx.tcx().expect_def(expr.id) {
297 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
298 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
299 debug!("get_const_expr_as_global ({:?}): found const {:?}",
301 return get_const_val(ccx, def_id, expr, param_substs);
308 let key = (expr.id, param_substs);
309 if let Some(&val) = ccx.const_values().borrow().get(&key) {
312 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
313 &ccx.tcx().expr_ty(expr));
314 let val = if qualif.intersects(ConstQualif::NON_STATIC_BORROWS) {
315 // Avoid autorefs as they would create global instead of stack
316 // references, even when only the latter are correct.
317 const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst)?
319 const_expr(ccx, expr, param_substs, None, trueconst)?.0
322 // boolean SSA values are i1, but they have to be stored in i8 slots,
323 // otherwise some LLVM optimization passes don't work as expected
325 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
326 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
332 let lvalue = addr_of(ccx, val, type_of::align_of(ccx, ty), "const");
333 ccx.const_values().borrow_mut().insert(key, lvalue);
337 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
339 param_substs: &'tcx Substs<'tcx>,
341 trueconst: TrueConst)
342 -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> {
343 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
344 &cx.tcx().expr_ty(e));
345 let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst)?;
346 let mut llconst = llconst;
347 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
348 &cx.tcx().expr_ty_adjusted(e));
349 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
351 Some(AdjustReifyFnPointer) => {
353 ty::TyFnDef(def_id, substs, _) => {
354 llconst = Callee::def(cx, def_id, substs).reify(cx).val;
357 bug!("{} cannot be reified to a fn ptr", ety)
361 Some(AdjustUnsafeFnPointer) | Some(AdjustMutToConstPointer) => {
362 // purely a type-level thing
364 Some(AdjustDerefRef(adj)) => {
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);
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::ReErased), ty);
382 } else if adj.autoderefs > 0 {
383 let (dv, dt) = const_deref(cx, llconst, ty);
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.
392 if let Some(target) = adj.unsize {
393 let target = monomorphize::apply_param_substs(cx.tcx(),
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
406 (const_get_elt(llconst, &[abi::FAT_PTR_ADDR as u32]),
407 Some(const_get_elt(llconst, &[abi::FAT_PTR_EXTRA as u32])))
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, old_info);
418 if old_info.is_none() {
419 let prev_const = cx.const_unsized().borrow_mut()
420 .insert(base, llconst);
421 assert!(prev_const.is_none() || prev_const == Some(llconst));
423 assert_eq!(abi::FAT_PTR_ADDR, 0);
424 assert_eq!(abi::FAT_PTR_EXTRA, 1);
425 llconst = C_struct(cx, &[base, info], false);
431 let llty = type_of::sizing_type_of(cx, ety_adjusted);
432 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
433 let tsize = machine::llsize_of_alloc(cx, llty);
435 cx.sess().abort_if_errors();
437 // FIXME these values could use some context
438 llvm::LLVMDumpValue(llconst);
439 llvm::LLVMDumpValue(C_undef(llty));
441 bug!("const {:?} of type {:?} has size {} instead of {}",
445 Ok((llconst, ety_adjusted))
448 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
449 te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
450 // The only kind of unary expression that we check for validity
451 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
452 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
454 // An unfortunate special case: we parse e.g. -128 as a
455 // negation of the literal 128, which means if we're expecting
456 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
457 // 128 will have already overflowed to -128, and so then the
458 // constant evaluator thinks we're trying to negate -128.
460 // Catch this up front by looking for ExprLit directly,
461 // and just accepting it.
462 if let hir::ExprLit(_) = inner_e.node { return Ok(()); }
463 let cval = match to_const_int(te, t, cx.tcx()) {
465 None => return Ok(()),
467 const_err(cx, e.span, (-cval).map_err(ErrKind::Math), trueconst)?;
472 pub fn to_const_int(value: ValueRef, t: Ty, tcx: TyCtxt) -> Option<ConstInt> {
474 ty::TyInt(int_type) => const_to_opt_int(value).and_then(|input| match int_type {
476 assert_eq!(input as i8 as i64, input);
477 Some(ConstInt::I8(input as i8))
480 assert_eq!(input as i16 as i64, input);
481 Some(ConstInt::I16(input as i16))
484 assert_eq!(input as i32 as i64, input);
485 Some(ConstInt::I32(input as i32))
488 Some(ConstInt::I64(input))
491 ConstIsize::new(input, tcx.sess.target.int_type)
492 .ok().map(ConstInt::Isize)
495 ty::TyUint(uint_type) => const_to_opt_uint(value).and_then(|input| match uint_type {
497 assert_eq!(input as u8 as u64, input);
498 Some(ConstInt::U8(input as u8))
500 ast::UintTy::U16 => {
501 assert_eq!(input as u16 as u64, input);
502 Some(ConstInt::U16(input as u16))
504 ast::UintTy::U32 => {
505 assert_eq!(input as u32 as u64, input);
506 Some(ConstInt::U32(input as u32))
508 ast::UintTy::U64 => {
509 Some(ConstInt::U64(input))
512 ConstUsize::new(input, tcx.sess.target.uint_type)
513 .ok().map(ConstInt::Usize)
520 pub fn const_err<T>(cx: &CrateContext,
522 result: Result<T, ErrKind>,
523 trueconst: TrueConst)
524 -> Result<T, ConstEvalFailure> {
525 match (result, trueconst) {
527 (Err(err), TrueConst::Yes) => {
528 let err = ConstEvalErr{ span: span, kind: err };
529 report_const_eval_err(cx.tcx(), &err, span, "expression").emit();
530 Err(Compiletime(err))
532 (Err(err), TrueConst::No) => {
533 let err = ConstEvalErr{ span: span, kind: err };
534 let mut diag = cx.tcx().sess.struct_span_warn(
535 span, "this expression will panic at run-time");
536 note_const_eval_err(cx.tcx(), &err, span, "expression", &mut diag);
543 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
544 te1: ValueRef, te2: ValueRef,
545 trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
546 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { bug!() };
547 let (lhs, rhs) = match (to_const_int(te1, t, cx.tcx()), to_const_int(te2, t, cx.tcx())) {
548 (Some(v1), Some(v2)) => (v1, v2),
551 let result = match b.node {
552 hir::BiAdd => lhs + rhs,
553 hir::BiSub => lhs - rhs,
554 hir::BiMul => lhs * rhs,
555 hir::BiDiv => lhs / rhs,
556 hir::BiRem => lhs % rhs,
557 hir::BiShl => lhs << rhs,
558 hir::BiShr => lhs >> rhs,
561 const_err(cx, e.span, result.map_err(ErrKind::Math), trueconst)?;
565 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
568 param_substs: &'tcx Substs<'tcx>,
570 trueconst: TrueConst)
571 -> Result<ValueRef, ConstEvalFailure>
573 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
578 let map_list = |exprs: &[P<hir::Expr>]| -> Result<Vec<ValueRef>, ConstEvalFailure> {
580 .map(|e| const_expr(cx, &e, param_substs, fn_args, trueconst).map(|(l, _)| l))
581 .collect::<Vec<Result<ValueRef, ConstEvalFailure>>>()
584 // this dance is necessary to eagerly run const_expr so all errors are reported
586 let _icx = push_ctxt("const_expr");
588 hir::ExprLit(ref lit) => const_lit(cx, e, &lit),
589 hir::ExprBinary(b, ref e1, ref e2) => {
590 /* Neither type is bottom, and we expect them to be unified
591 * already, so the following is safe. */
592 let (te1, ty) = const_expr(cx, &e1, param_substs, fn_args, trueconst)?;
593 debug!("const_expr_unadjusted: te1={:?}, ty={:?}",
595 assert!(!ty.is_simd());
596 let is_float = ty.is_fp();
597 let signed = ty.is_signed();
599 let (te2, ty2) = const_expr(cx, &e2, param_substs, fn_args, trueconst)?;
600 debug!("const_expr_unadjusted: te2={:?}, ty={:?}",
603 check_binary_expr_validity(cx, e, ty, te1, te2, trueconst)?;
605 unsafe { match b.node {
606 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
607 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
609 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
610 hir::BiSub => llvm::LLVMConstSub(te1, te2),
612 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
613 hir::BiMul => llvm::LLVMConstMul(te1, te2),
615 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
616 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
617 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
619 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
620 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
621 hir::BiRem => llvm::LLVMConstURem(te1, te2),
623 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
624 hir::BiOr => llvm::LLVMConstOr(te1, te2),
625 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
626 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
627 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
629 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
630 llvm::LLVMConstShl(te1, te2)
633 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
634 if signed { llvm::LLVMConstAShr(te1, te2) }
635 else { llvm::LLVMConstLShr(te1, te2) }
637 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
639 let cmp = base::bin_op_to_fcmp_predicate(b.node);
640 llvm::LLVMConstFCmp(cmp, te1, te2)
642 let cmp = base::bin_op_to_icmp_predicate(b.node, signed);
643 llvm::LLVMConstICmp(cmp, te1, te2)
646 } } // unsafe { match b.node {
648 hir::ExprUnary(u, ref inner_e) => {
649 let (te, ty) = const_expr(cx, &inner_e, param_substs, fn_args, trueconst)?;
651 check_unary_expr_validity(cx, e, ty, te, trueconst)?;
653 let is_float = ty.is_fp();
655 hir::UnDeref => const_deref(cx, te, ty).0,
656 hir::UnNot => llvm::LLVMConstNot(te),
657 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
658 hir::UnNeg => llvm::LLVMConstNeg(te),
661 hir::ExprField(ref base, field) => {
662 let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
663 let brepr = adt::represent_type(cx, bt);
664 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
665 let ix = vinfo.field_index(field.node);
666 adt::const_get_field(&brepr, bv, vinfo.discr, ix)
668 hir::ExprTupField(ref base, idx) => {
669 let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
670 let brepr = adt::represent_type(cx, bt);
671 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
672 adt::const_get_field(&brepr, bv, vinfo.discr, idx.node)
674 hir::ExprIndex(ref base, ref index) => {
675 let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
676 let iv = const_expr(cx, &index, param_substs, fn_args, TrueConst::Yes)?.0;
677 let iv = if let Some(iv) = const_to_opt_uint(iv) {
680 span_bug!(index.span, "index is not an integer-constant expression");
682 let (arr, len) = match bt.sty {
683 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
684 ty::TySlice(..) | ty::TyStr => {
685 let e1 = const_get_elt(bv, &[0]);
686 (load_const(cx, e1, bt), const_get_elt(bv, &[1]))
688 ty::TyRef(_, mt) => match mt.ty.sty {
689 ty::TyArray(_, u) => {
690 (load_const(cx, bv, mt.ty), C_uint(cx, u))
692 _ => span_bug!(base.span,
693 "index-expr base must be a vector \
694 or string type, found {:?}",
697 _ => span_bug!(base.span,
698 "index-expr base must be a vector \
699 or string type, found {:?}",
703 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
704 let len = match bt.sty {
705 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
715 // FIXME #3170: report this earlier on in the const-eval
716 // pass. Reporting here is a bit late.
717 const_err(cx, e.span, Err(ErrKind::IndexOutOfBounds {
721 C_undef(val_ty(arr).element_type())
723 const_get_elt(arr, &[iv as c_uint])
726 hir::ExprCast(ref base, _) => {
728 let llty = type_of::type_of(cx, t_cast);
729 let (v, t_expr) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
730 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
731 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
734 if type_is_fat_ptr(cx.tcx(), t_expr) {
735 // Fat pointer casts.
737 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
738 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
739 let addr = ptrcast(const_get_elt(v, &[abi::FAT_PTR_ADDR as u32]),
741 if type_is_fat_ptr(cx.tcx(), t_cast) {
742 let info = const_get_elt(v, &[abi::FAT_PTR_EXTRA as u32]);
743 return Ok(C_struct(cx, &[addr, info], false))
749 CastTy::from_ty(t_expr).expect("bad input type for cast"),
750 CastTy::from_ty(t_cast).expect("bad output type for cast"),
752 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
753 let repr = adt::represent_type(cx, t_expr);
754 let discr = adt::const_get_discrim(&repr, v);
755 let iv = C_integral(cx.int_type(), discr.0, false);
756 let s = adt::is_discr_signed(&repr) as Bool;
757 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
759 (CastTy::Int(_), CastTy::Int(_)) => {
760 let s = t_expr.is_signed() as Bool;
761 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
763 (CastTy::Int(_), CastTy::Float) => {
764 if t_expr.is_signed() {
765 llvm::LLVMConstSIToFP(v, llty.to_ref())
767 llvm::LLVMConstUIToFP(v, llty.to_ref())
770 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
771 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
772 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
773 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
774 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
777 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
778 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
779 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
780 llvm::LLVMConstPtrToInt(v, llty.to_ref())
783 span_bug!(e.span, "bad combination of types for cast")
785 } } // unsafe { match ( ... ) {
787 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
788 // If this is the address of some static, then we need to return
789 // the actual address of the static itself (short circuit the rest
794 hir::ExprBlock(ref blk) => {
795 if let Some(ref sub) = blk.expr {
804 if let Some(Def::Static(def_id, _)) = cx.tcx().expect_def_or_none(cur.id) {
805 get_static(cx, def_id).val
807 // If this isn't the address of a static, then keep going through
808 // normal constant evaluation.
809 let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?;
810 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
813 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
814 let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?;
815 addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
817 hir::ExprTup(ref es) => {
818 let repr = adt::represent_type(cx, ety);
819 let vals = map_list(&es[..])?;
820 adt::trans_const(cx, &repr, Disr(0), &vals[..])
822 hir::ExprStruct(_, ref fs, ref base_opt) => {
823 let repr = adt::represent_type(cx, ety);
825 let base_val = match *base_opt {
826 Some(ref base) => Some(const_expr(
836 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
837 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
838 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
839 (Some(ref f), _) => {
840 const_expr(cx, &f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l)
842 (_, Some((bv, _))) => Ok(adt::const_get_field(&repr, bv, discr, ix)),
843 (_, None) => span_bug!(e.span, "missing struct field"),
846 .collect::<Vec<Result<_, ConstEvalFailure>>>()
848 .collect::<Result<Vec<_>,ConstEvalFailure>>();
853 adt::trans_const(cx, &repr, discr, &cs[..])
856 hir::ExprVec(ref es) => {
857 let unit_ty = ety.sequence_element_type(cx.tcx());
858 let llunitty = type_of::type_of(cx, unit_ty);
867 .collect::<Vec<Result<_, ConstEvalFailure>>>()
869 .collect::<Result<Vec<_>, ConstEvalFailure>>();
871 // If the vector contains enums, an LLVM array won't work.
872 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
873 C_struct(cx, &vs[..], false)
875 C_array(llunitty, &vs[..])
878 hir::ExprRepeat(ref elem, ref count) => {
879 let unit_ty = ety.sequence_element_type(cx.tcx());
880 let llunitty = type_of::type_of(cx, unit_ty);
881 let n = eval_length(cx.tcx(), count, "repeat count").unwrap();
882 let unit_val = const_expr(cx, &elem, param_substs, fn_args, trueconst)?.0;
883 let vs = vec![unit_val; n];
884 if val_ty(unit_val) != llunitty {
885 C_struct(cx, &vs[..], false)
887 C_array(llunitty, &vs[..])
890 hir::ExprPath(..) => {
891 match cx.tcx().expect_def(e.id) {
892 Def::Local(_, id) => {
893 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
896 span_bug!(e.span, "const fn argument not found")
899 Def::Fn(..) | Def::Method(..) => C_nil(cx),
900 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
901 load_const(cx, get_const_val(cx, def_id, e, param_substs)?,
904 Def::Variant(enum_did, variant_did) => {
905 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
907 ty::VariantKind::Unit => {
908 let repr = adt::represent_type(cx, ety);
909 adt::trans_const(cx, &repr, Disr::from(vinfo.disr_val), &[])
911 ty::VariantKind::Tuple => C_nil(cx),
912 ty::VariantKind::Struct => {
913 span_bug!(e.span, "path-expr refers to a dict variant!")
917 // Unit struct or ctor.
918 Def::Struct(..) => C_null(type_of::type_of(cx, ety)),
920 span_bug!(e.span, "expected a const, fn, struct, \
925 hir::ExprCall(ref callee, ref args) => {
926 let mut callee = &**callee;
928 callee = match callee.node {
929 hir::ExprBlock(ref block) => match block.expr {
930 Some(ref tail) => &tail,
936 let arg_vals = map_list(args)?;
937 match cx.tcx().expect_def(callee.id) {
938 Def::Fn(did) | Def::Method(did) => {
942 cx.tcx().node_id_item_substs(callee.id).substs,
950 C_vector(&arg_vals[..])
952 let repr = adt::represent_type(cx, ety);
953 adt::trans_const(cx, &repr, Disr(0), &arg_vals[..])
956 Def::Variant(enum_did, variant_did) => {
957 let repr = adt::represent_type(cx, ety);
958 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
961 Disr::from(vinfo.disr_val),
964 _ => span_bug!(e.span, "expected a struct, variant, or const fn def"),
967 hir::ExprMethodCall(_, _, ref args) => {
968 let arg_vals = map_list(args)?;
969 let method_call = ty::MethodCall::expr(e.id);
970 let method = cx.tcx().tables.borrow().method_map[&method_call];
971 const_fn_call(cx, method.def_id, method.substs,
972 &arg_vals, param_substs, trueconst)?
974 hir::ExprType(ref e, _) => const_expr(cx, &e, param_substs, fn_args, trueconst)?.0,
975 hir::ExprBlock(ref block) => {
977 Some(ref expr) => const_expr(
987 hir::ExprClosure(_, ref decl, ref body, _) => {
989 ty::TyClosure(def_id, substs) => {
990 closure::trans_closure_expr(closure::Dest::Ignore(cx),
1000 "bad type for closure expr: {:?}", ety)
1002 C_null(type_of::type_of(cx, ety))
1004 _ => span_bug!(e.span,
1005 "bad constant expression type in consts::const_expr"),
1009 pub fn get_static<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, def_id: DefId)
1010 -> Datum<'tcx, Lvalue> {
1011 let ty = ccx.tcx().lookup_item_type(def_id).ty;
1013 let instance = Instance::mono(ccx.shared(), def_id);
1014 if let Some(&g) = ccx.instances().borrow().get(&instance) {
1015 return Datum::new(g, ty, Lvalue::new("static"));
1018 let g = if let Some(id) = ccx.tcx().map.as_local_node_id(def_id) {
1020 let llty = type_of::type_of(ccx, ty);
1021 let (g, attrs) = match ccx.tcx().map.get(id) {
1022 hir_map::NodeItem(&hir::Item {
1023 ref attrs, span, node: hir::ItemStatic(..), ..
1025 let sym = ccx.symbol_map()
1026 .get(TransItem::Static(id))
1027 .expect("Local statics should always be in the SymbolMap");
1028 // Make sure that this is never executed for something inlined.
1029 assert!(!ccx.tcx().map.is_inlined_node_id(id));
1031 let defined_in_current_codegen_unit = ccx.codegen_unit()
1033 .contains_key(&TransItem::Static(id));
1034 if defined_in_current_codegen_unit {
1035 if declare::get_declared_value(ccx, sym).is_none() {
1036 span_bug!(span, "trans: Static not properly pre-defined?");
1039 if declare::get_declared_value(ccx, sym).is_some() {
1040 span_bug!(span, "trans: Conflicting symbol names for static?");
1044 let g = declare::define_global(ccx, sym, llty).unwrap();
1049 hir_map::NodeForeignItem(&hir::ForeignItem {
1050 ref attrs, span, node: hir::ForeignItemStatic(..), ..
1052 let sym = instance.symbol_name(ccx.shared());
1053 let g = if let Some(name) =
1054 attr::first_attr_value_str_by_name(&attrs, "linkage") {
1055 // If this is a static with a linkage specified, then we need to handle
1056 // it a little specially. The typesystem prevents things like &T and
1057 // extern "C" fn() from being non-null, so we can't just declare a
1058 // static and call it a day. Some linkages (like weak) will make it such
1059 // that the static actually has a null value.
1060 let linkage = match base::llvm_linkage_by_name(&name) {
1061 Some(linkage) => linkage,
1063 ccx.sess().span_fatal(span, "invalid linkage specified");
1066 let llty2 = match ty.sty {
1067 ty::TyRawPtr(ref mt) => type_of::type_of(ccx, mt.ty),
1069 ccx.sess().span_fatal(span, "must have type `*const T` or `*mut T`");
1073 // Declare a symbol `foo` with the desired linkage.
1074 let g1 = declare::declare_global(ccx, &sym, llty2);
1075 llvm::LLVMSetLinkage(g1, linkage);
1077 // Declare an internal global `extern_with_linkage_foo` which
1078 // is initialized with the address of `foo`. If `foo` is
1079 // discarded during linking (for example, if `foo` has weak
1080 // linkage and there are no definitions), then
1081 // `extern_with_linkage_foo` will instead be initialized to
1083 let mut real_name = "_rust_extern_with_linkage_".to_string();
1084 real_name.push_str(&sym);
1085 let g2 = declare::define_global(ccx, &real_name, llty).unwrap_or_else(||{
1086 ccx.sess().span_fatal(span,
1087 &format!("symbol `{}` is already defined", &sym))
1089 llvm::LLVMSetLinkage(g2, llvm::InternalLinkage);
1090 llvm::LLVMSetInitializer(g2, g1);
1094 // Generate an external declaration.
1095 declare::declare_global(ccx, &sym, llty)
1101 item => bug!("get_static: expected static, found {:?}", item)
1105 if attr.check_name("thread_local") {
1106 llvm::set_thread_local(g, true);
1112 let sym = instance.symbol_name(ccx.shared());
1114 // FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow?
1115 // FIXME(nagisa): investigate whether it can be changed into define_global
1116 let g = declare::declare_global(ccx, &sym, type_of::type_of(ccx, ty));
1117 // Thread-local statics in some other crate need to *always* be linked
1118 // against in a thread-local fashion, so we need to be sure to apply the
1119 // thread-local attribute locally if it was present remotely. If we
1120 // don't do this then linker errors can be generated where the linker
1121 // complains that one object files has a thread local version of the
1122 // symbol and another one doesn't.
1123 for attr in ccx.tcx().get_attrs(def_id).iter() {
1124 if attr.check_name("thread_local") {
1125 llvm::set_thread_local(g, true);
1128 if ccx.use_dll_storage_attrs() {
1130 llvm::LLVMSetDLLStorageClass(g, llvm::DLLStorageClass::DllImport);
1136 ccx.instances().borrow_mut().insert(instance, g);
1137 ccx.statics().borrow_mut().insert(g, def_id);
1138 Datum::new(g, ty, Lvalue::new("static"))
1141 pub fn trans_static(ccx: &CrateContext,
1145 attrs: &[ast::Attribute])
1146 -> Result<ValueRef, ConstEvalErr> {
1148 let _icx = push_ctxt("trans_static");
1149 let def_id = ccx.tcx().map.local_def_id(id);
1150 let datum = get_static(ccx, def_id);
1152 let check_attrs = |attrs: &[ast::Attribute]| {
1153 let default_to_mir = ccx.sess().opts.debugging_opts.orbit;
1154 let invert = if default_to_mir { "rustc_no_mir" } else { "rustc_mir" };
1155 default_to_mir ^ attrs.iter().any(|item| item.check_name(invert))
1157 let use_mir = check_attrs(ccx.tcx().map.attrs(id));
1159 let v = if use_mir {
1160 ::mir::trans_static_initializer(ccx, def_id)
1162 let empty_substs = ccx.tcx().mk_substs(Substs::empty());
1163 const_expr(ccx, expr, empty_substs, None, TrueConst::Yes)
1165 }.map_err(|e| e.into_inner())?;
1167 // boolean SSA values are i1, but they have to be stored in i8 slots,
1168 // otherwise some LLVM optimization passes don't work as expected
1169 let mut val_llty = val_ty(v);
1170 let v = if val_llty == Type::i1(ccx) {
1171 val_llty = Type::i8(ccx);
1172 llvm::LLVMConstZExt(v, val_llty.to_ref())
1177 let llty = type_of::type_of(ccx, datum.ty);
1178 let g = if val_llty == llty {
1181 // If we created the global with the wrong type,
1182 // correct the type.
1183 let empty_string = CString::new("").unwrap();
1184 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(datum.val));
1185 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
1186 llvm::LLVMSetValueName(datum.val, empty_string.as_ptr());
1187 let new_g = llvm::LLVMRustGetOrInsertGlobal(
1188 ccx.llmod(), name_string.as_ptr(), val_llty.to_ref());
1189 // To avoid breaking any invariants, we leave around the old
1190 // global for the moment; we'll replace all references to it
1191 // with the new global later. (See base::trans_crate.)
1192 ccx.statics_to_rauw().borrow_mut().push((datum.val, new_g));
1195 llvm::LLVMSetAlignment(g, type_of::align_of(ccx, datum.ty));
1196 llvm::LLVMSetInitializer(g, v);
1198 // As an optimization, all shared statics which do not have interior
1199 // mutability are placed into read-only memory.
1200 if m != hir::MutMutable {
1201 let tcontents = datum.ty.type_contents(ccx.tcx());
1202 if !tcontents.interior_unsafe() {
1203 llvm::LLVMSetGlobalConstant(g, llvm::True);
1207 debuginfo::create_global_var_metadata(ccx, id, g);
1209 if attr::contains_name(attrs,
1211 llvm::set_thread_local(g, true);
1214 base::set_link_section(ccx, g, attrs);