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::{ConstFCmp, ConstICmp, SetLinkage, SetUnnamedAddr};
14 use llvm::{InternalLinkage, ValueRef, Bool, True};
15 use middle::const_qualif::ConstQualif;
16 use middle::const_eval::{self, ConstEvalErr};
18 use middle::def_id::DefId;
19 use rustc::front::map as hir_map;
20 use trans::{abi, adt, closure, debuginfo, expr, machine};
21 use trans::base::{self, exported_name, imported_name, push_ctxt};
22 use trans::callee::Callee;
23 use trans::collector::{self, TransItem};
24 use trans::common::{type_is_sized, C_nil, const_get_elt};
25 use trans::common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty};
26 use trans::common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint};
27 use trans::common::{type_is_fat_ptr, Field, C_vector, C_array, C_null};
28 use trans::datum::{Datum, Lvalue};
30 use trans::monomorphize::{self, Instance};
31 use trans::type_::Type;
33 use trans::value::Value;
35 use middle::subst::Substs;
36 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
37 use middle::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer};
38 use middle::ty::{self, Ty, TyCtxt};
39 use middle::ty::cast::{CastTy,IntTy};
40 use util::nodemap::NodeMap;
41 use rustc_const_eval::{ConstInt, ConstMathErr, ConstUsize, ConstIsize};
45 use std::ffi::{CStr, CString};
48 use syntax::ast::{self, LitKind};
49 use syntax::attr::{self, AttrMetaMethods};
50 use syntax::parse::token;
53 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
55 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit)
57 let _icx = push_ctxt("trans_lit");
58 debug!("const_lit: {:?}", lit);
60 LitKind::Byte(b) => C_integral(Type::uint_from_ty(cx, ast::UintTy::U8), b as u64, false),
61 LitKind::Char(i) => C_integral(Type::char(cx), i as u64, false),
62 LitKind::Int(i, ast::LitIntType::Signed(t)) => {
63 C_integral(Type::int_from_ty(cx, t), i, true)
65 LitKind::Int(u, ast::LitIntType::Unsigned(t)) => {
66 C_integral(Type::uint_from_ty(cx, t), u, false)
68 LitKind::Int(i, ast::LitIntType::Unsuffixed) => {
69 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
70 match lit_int_ty.sty {
72 C_integral(Type::int_from_ty(cx, t), i as u64, true)
75 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
77 _ => cx.sess().span_bug(lit.span,
78 &format!("integer literal has type {:?} (expected int \
83 LitKind::Float(ref fs, t) => {
84 C_floating(&fs, Type::float_from_ty(cx, t))
86 LitKind::FloatUnsuffixed(ref fs) => {
87 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
88 match lit_float_ty.sty {
90 C_floating(&fs, Type::float_from_ty(cx, t))
93 cx.sess().span_bug(lit.span,
94 "floating point literal doesn't have the right type");
98 LitKind::Bool(b) => C_bool(cx, b),
99 LitKind::Str(ref s, _) => C_str_slice(cx, (*s).clone()),
100 LitKind::ByteStr(ref data) => {
101 addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str")
106 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
108 llvm::LLVMConstPointerCast(val, ty.to_ref())
112 fn addr_of_mut(ccx: &CrateContext,
114 align: machine::llalign,
118 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
119 // counter? Also most other uses of gensym in trans.
120 let gsym = token::gensym("_");
121 let name = format!("{}{}", kind, gsym.0);
122 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
123 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
125 llvm::LLVMSetInitializer(gv, cv);
126 llvm::LLVMSetAlignment(gv, align);
127 SetLinkage(gv, InternalLinkage);
128 SetUnnamedAddr(gv, true);
133 pub fn addr_of(ccx: &CrateContext,
135 align: machine::llalign,
138 match 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);
151 let gv = addr_of_mut(ccx, cv, align, kind);
153 llvm::LLVMSetGlobalConstant(gv, True);
155 ccx.const_globals().borrow_mut().insert(cv, gv);
159 /// Deref a constant pointer
160 fn load_const(cx: &CrateContext, v: ValueRef, t: Ty) -> ValueRef {
161 let v = match cx.const_unsized().borrow().get(&v) {
165 let d = unsafe { llvm::LLVMGetInitializer(v) };
167 unsafe { llvm::LLVMConstTrunc(d, Type::i1(cx).to_ref()) }
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 (load_const(cx, v, mt.ty), 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>,
196 substs: Substs<'tcx>,
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 body = match fn_like.body().expr {
204 Some(ref expr) => expr,
205 None => return Ok(C_nil(ccx))
208 let args = &fn_like.decl().inputs;
209 assert_eq!(args.len(), arg_vals.len());
211 let arg_ids = args.iter().map(|arg| arg.pat.id);
212 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
214 let substs = monomorphize::apply_param_substs(ccx.tcx(),
216 &substs.erase_regions());
217 let substs = ccx.tcx().mk_substs(substs);
219 const_expr(ccx, body, substs, Some(&fn_args), trueconst).map(|(res, _)| res)
222 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
224 ref_expr: &hir::Expr,
225 param_substs: &'tcx Substs<'tcx>)
227 let substs = ccx.tcx().node_id_item_substs(ref_expr.id).substs;
228 let substs = monomorphize::apply_param_substs(ccx.tcx(),
230 &substs.erase_regions());
231 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(substs)) {
232 Some((ref expr, _ty)) => expr,
234 ccx.sess().span_bug(ref_expr.span, "constant item not found")
239 pub enum ConstEvalFailure {
240 /// in case the const evaluator failed on something that panic at runtime
241 /// as defined in RFC 1229
242 Runtime(ConstEvalErr),
243 // in case we found a true constant
244 Compiletime(ConstEvalErr),
247 impl ConstEvalFailure {
248 fn into_inner(self) -> ConstEvalErr {
254 pub fn description(&self) -> Cow<str> {
256 &Runtime(ref e) => e.description(),
257 &Compiletime(ref e) => e.description(),
262 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
267 use self::ConstEvalFailure::*;
269 fn get_const_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
271 ref_expr: &hir::Expr,
272 param_substs: &'tcx Substs<'tcx>)
273 -> Result<ValueRef, ConstEvalFailure> {
274 let expr = get_const_expr(ccx, def_id, ref_expr, param_substs);
275 let empty_substs = ccx.tcx().mk_substs(Substs::empty());
276 match get_const_expr_as_global(ccx, expr, ConstQualif::empty(), empty_substs, TrueConst::Yes) {
277 Err(Runtime(err)) => {
278 ccx.tcx().sess.span_err(expr.span, &err.description());
279 Err(Compiletime(err))
285 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
288 param_substs: &'tcx Substs<'tcx>,
289 trueconst: TrueConst)
290 -> Result<ValueRef, ConstEvalFailure> {
291 debug!("get_const_expr_as_global: {:?}", expr.id);
292 // Special-case constants to cache a common global for all uses.
293 if let hir::ExprPath(..) = expr.node {
294 // `def` must be its own statement and cannot be in the `match`
295 // otherwise the `def_map` will be borrowed for the entire match instead
296 // of just to get the `def` value
297 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
299 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
300 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
301 debug!("get_const_expr_as_global ({:?}): found const {:?}",
303 return get_const_val(ccx, def_id, expr, param_substs);
310 let key = (expr.id, param_substs);
311 if let Some(&val) = ccx.const_values().borrow().get(&key) {
314 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
315 &ccx.tcx().expr_ty(expr));
316 let val = if qualif.intersects(ConstQualif::NON_STATIC_BORROWS) {
317 // Avoid autorefs as they would create global instead of stack
318 // references, even when only the latter are correct.
319 const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst)?
321 const_expr(ccx, expr, param_substs, None, trueconst)?.0
324 // boolean SSA values are i1, but they have to be stored in i8 slots,
325 // otherwise some LLVM optimization passes don't work as expected
327 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
328 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
334 let lvalue = addr_of(ccx, val, type_of::align_of(ccx, ty), "const");
335 ccx.const_values().borrow_mut().insert(key, lvalue);
339 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
341 param_substs: &'tcx Substs<'tcx>,
343 trueconst: TrueConst)
344 -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> {
345 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
346 &cx.tcx().expr_ty(e));
347 let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst)?;
348 let mut llconst = llconst;
349 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
350 &cx.tcx().expr_ty_adjusted(e));
351 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
353 Some(AdjustReifyFnPointer) => {
355 ty::TyFnDef(def_id, substs, _) => {
356 llconst = Callee::def(cx, def_id, substs).reify(cx).val;
359 unreachable!("{} cannot be reified to a fn ptr", ety)
363 Some(AdjustUnsafeFnPointer) | Some(AdjustMutToConstPointer) => {
364 // purely a type-level thing
366 Some(AdjustDerefRef(adj)) => {
368 // Save the last autoderef in case we can avoid it.
369 if adj.autoderefs > 0 {
370 for _ in 0..adj.autoderefs-1 {
371 let (dv, dt) = const_deref(cx, llconst, ty);
377 if adj.autoref.is_some() {
378 if adj.autoderefs == 0 {
379 // Don't copy data to do a deref+ref
380 // (i.e., skip the last auto-deref).
381 llconst = addr_of(cx, llconst, type_of::align_of(cx, ty), "autoref");
382 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
384 } else if adj.autoderefs > 0 {
385 let (dv, dt) = const_deref(cx, llconst, ty);
388 // If we derefed a fat pointer then we will have an
389 // open type here. So we need to update the type with
390 // the one returned from const_deref.
394 if let Some(target) = adj.unsize {
395 let target = monomorphize::apply_param_substs(cx.tcx(),
399 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
400 .expect("consts: unsizing got non-pointer type").ty;
401 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
402 // Normally, the source is a thin pointer and we are
403 // adding extra info to make a fat pointer. The exception
404 // is when we are upcasting an existing object fat pointer
405 // to use a different vtable. In that case, we want to
406 // load out the original data pointer so we can repackage
408 (const_get_elt(llconst, &[abi::FAT_PTR_ADDR as u32]),
409 Some(const_get_elt(llconst, &[abi::FAT_PTR_EXTRA as u32])))
414 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
415 .expect("consts: unsizing got non-pointer target type").ty;
416 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
417 let base = ptrcast(base, ptr_ty);
418 let info = base::unsized_info(cx, pointee_ty, unsized_ty, old_info);
420 if old_info.is_none() {
421 let prev_const = cx.const_unsized().borrow_mut()
422 .insert(base, llconst);
423 assert!(prev_const.is_none() || prev_const == Some(llconst));
425 assert_eq!(abi::FAT_PTR_ADDR, 0);
426 assert_eq!(abi::FAT_PTR_EXTRA, 1);
427 llconst = C_struct(cx, &[base, info], false);
433 let llty = type_of::sizing_type_of(cx, ety_adjusted);
434 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
435 let tsize = machine::llsize_of_alloc(cx, llty);
437 cx.sess().abort_if_errors();
439 // FIXME these values could use some context
440 llvm::LLVMDumpValue(llconst);
441 llvm::LLVMDumpValue(C_undef(llty));
443 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
447 Ok((llconst, ety_adjusted))
450 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
451 te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
452 // The only kind of unary expression that we check for validity
453 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
454 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
456 // An unfortunate special case: we parse e.g. -128 as a
457 // negation of the literal 128, which means if we're expecting
458 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
459 // 128 will have already overflowed to -128, and so then the
460 // constant evaluator thinks we're trying to negate -128.
462 // Catch this up front by looking for ExprLit directly,
463 // and just accepting it.
464 if let hir::ExprLit(_) = inner_e.node { return Ok(()); }
465 let cval = match to_const_int(te, t, cx.tcx()) {
467 None => return Ok(()),
470 Ok(_) => return Ok(()),
471 Err(err) => const_err(cx, e, Err(err), trueconst),
478 fn to_const_int(value: ValueRef, t: Ty, tcx: &TyCtxt) -> Option<ConstInt> {
480 ty::TyInt(int_type) => const_to_opt_int(value).and_then(|input| match int_type {
482 assert_eq!(input as i8 as i64, input);
483 Some(ConstInt::I8(input as i8))
486 assert_eq!(input as i16 as i64, input);
487 Some(ConstInt::I16(input as i16))
490 assert_eq!(input as i32 as i64, input);
491 Some(ConstInt::I32(input as i32))
494 Some(ConstInt::I64(input))
497 ConstIsize::new(input, tcx.sess.target.int_type)
498 .ok().map(ConstInt::Isize)
501 ty::TyUint(uint_type) => const_to_opt_uint(value).and_then(|input| match uint_type {
503 assert_eq!(input as u8 as u64, input);
504 Some(ConstInt::U8(input as u8))
506 ast::UintTy::U16 => {
507 assert_eq!(input as u16 as u64, input);
508 Some(ConstInt::U16(input as u16))
510 ast::UintTy::U32 => {
511 assert_eq!(input as u32 as u64, input);
512 Some(ConstInt::U32(input as u32))
514 ast::UintTy::U64 => {
515 Some(ConstInt::U64(input))
518 ConstUsize::new(input, tcx.sess.target.uint_type)
519 .ok().map(ConstInt::Usize)
526 fn const_err(cx: &CrateContext,
528 result: Result<ConstInt, ConstMathErr>,
529 trueconst: TrueConst)
530 -> Result<(), ConstEvalFailure> {
531 match (result, trueconst) {
533 // We do not actually care about a successful result.
536 (Err(err), TrueConst::Yes) => {
537 let err = ConstEvalErr{ span: e.span, kind: const_eval::ErrKind::Math(err) };
538 cx.tcx().sess.span_err(e.span, &err.description());
539 Err(Compiletime(err))
541 (Err(err), TrueConst::No) => {
542 let err = ConstEvalErr{ span: e.span, kind: const_eval::ErrKind::Math(err) };
543 cx.tcx().sess.span_warn(e.span, &err.description());
549 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
550 te1: ValueRef, te2: ValueRef,
551 trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
552 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { unreachable!() };
553 let (lhs, rhs) = match (to_const_int(te1, t, cx.tcx()), to_const_int(te2, t, cx.tcx())) {
554 (Some(v1), Some(v2)) => (v1, v2),
557 let result = match b.node {
558 hir::BiAdd => lhs + rhs,
559 hir::BiSub => lhs - rhs,
560 hir::BiMul => lhs * rhs,
561 hir::BiDiv => lhs / rhs,
562 hir::BiRem => lhs % rhs,
563 hir::BiShl => lhs << rhs,
564 hir::BiShr => lhs >> rhs,
567 const_err(cx, e, result, trueconst)
570 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
573 param_substs: &'tcx Substs<'tcx>,
575 trueconst: TrueConst)
576 -> Result<ValueRef, ConstEvalFailure>
578 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
583 let map_list = |exprs: &[P<hir::Expr>]| -> Result<Vec<ValueRef>, ConstEvalFailure> {
585 .map(|e| const_expr(cx, &e, param_substs, fn_args, trueconst).map(|(l, _)| l))
586 .collect::<Vec<Result<ValueRef, ConstEvalFailure>>>()
589 // this dance is necessary to eagerly run const_expr so all errors are reported
591 let _icx = push_ctxt("const_expr");
593 hir::ExprLit(ref lit) => const_lit(cx, e, &lit),
594 hir::ExprBinary(b, ref e1, ref e2) => {
595 /* Neither type is bottom, and we expect them to be unified
596 * already, so the following is safe. */
597 let (te1, ty) = const_expr(cx, &e1, param_substs, fn_args, trueconst)?;
598 debug!("const_expr_unadjusted: te1={:?}, ty={:?}",
600 assert!(!ty.is_simd());
601 let is_float = ty.is_fp();
602 let signed = ty.is_signed();
604 let (te2, ty2) = const_expr(cx, &e2, param_substs, fn_args, trueconst)?;
605 debug!("const_expr_unadjusted: te2={:?}, ty={:?}",
608 check_binary_expr_validity(cx, e, ty, te1, te2, trueconst)?;
610 unsafe { match b.node {
611 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
612 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
614 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
615 hir::BiSub => llvm::LLVMConstSub(te1, te2),
617 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
618 hir::BiMul => llvm::LLVMConstMul(te1, te2),
620 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
621 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
622 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
624 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
625 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
626 hir::BiRem => llvm::LLVMConstURem(te1, te2),
628 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
629 hir::BiOr => llvm::LLVMConstOr(te1, te2),
630 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
631 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
632 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
634 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
635 llvm::LLVMConstShl(te1, te2)
638 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
639 if signed { llvm::LLVMConstAShr(te1, te2) }
640 else { llvm::LLVMConstLShr(te1, te2) }
642 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
644 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
645 ConstFCmp(cmp, te1, te2)
647 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
648 ConstICmp(cmp, te1, te2)
651 } } // unsafe { match b.node {
653 hir::ExprUnary(u, ref inner_e) => {
654 let (te, ty) = const_expr(cx, &inner_e, param_substs, fn_args, trueconst)?;
656 check_unary_expr_validity(cx, e, ty, te, trueconst)?;
658 let is_float = ty.is_fp();
660 hir::UnDeref => const_deref(cx, te, ty).0,
661 hir::UnNot => llvm::LLVMConstNot(te),
662 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
663 hir::UnNeg => llvm::LLVMConstNeg(te),
666 hir::ExprField(ref base, field) => {
667 let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
668 let brepr = adt::represent_type(cx, bt);
669 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
670 let ix = vinfo.field_index(field.node);
671 adt::const_get_field(cx, &brepr, bv, vinfo.discr, ix)
673 hir::ExprTupField(ref base, idx) => {
674 let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
675 let brepr = adt::represent_type(cx, bt);
676 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
677 adt::const_get_field(cx, &brepr, bv, vinfo.discr, idx.node)
679 hir::ExprIndex(ref base, ref index) => {
680 let (bv, bt) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
681 let iv = const_expr(cx, &index, param_substs, fn_args, TrueConst::Yes)?.0;
682 let iv = if let Some(iv) = const_to_opt_uint(iv) {
685 cx.sess().span_bug(index.span, "index is not an integer-constant expression");
687 let (arr, len) = match bt.sty {
688 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
689 ty::TySlice(..) | ty::TyStr => {
690 let e1 = const_get_elt(bv, &[0]);
691 (load_const(cx, e1, bt), const_get_elt(bv, &[1]))
693 ty::TyRef(_, mt) => match mt.ty.sty {
694 ty::TyArray(_, u) => {
695 (load_const(cx, bv, mt.ty), C_uint(cx, u))
697 _ => cx.sess().span_bug(base.span,
698 &format!("index-expr base must be a vector \
699 or string type, found {:?}",
702 _ => cx.sess().span_bug(base.span,
703 &format!("index-expr base must be a vector \
704 or string type, found {:?}",
708 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
709 let len = match bt.sty {
710 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
720 // FIXME #3170: report this earlier on in the const-eval
721 // pass. Reporting here is a bit late.
722 span_err!(cx.sess(), e.span, E0515,
723 "const index-expr is out of bounds");
724 C_undef(val_ty(arr).element_type())
726 const_get_elt(arr, &[iv as c_uint])
729 hir::ExprCast(ref base, _) => {
731 let llty = type_of::type_of(cx, t_cast);
732 let (v, t_expr) = const_expr(cx, &base, param_substs, fn_args, trueconst)?;
733 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
734 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
737 if type_is_fat_ptr(cx.tcx(), t_expr) {
738 // Fat pointer casts.
740 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
741 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
742 let addr = ptrcast(const_get_elt(v, &[abi::FAT_PTR_ADDR as u32]),
744 if type_is_fat_ptr(cx.tcx(), t_cast) {
745 let info = const_get_elt(v, &[abi::FAT_PTR_EXTRA as u32]);
746 return Ok(C_struct(cx, &[addr, info], false))
752 CastTy::from_ty(t_expr).expect("bad input type for cast"),
753 CastTy::from_ty(t_cast).expect("bad output type for cast"),
755 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
756 let repr = adt::represent_type(cx, t_expr);
757 let discr = adt::const_get_discrim(&repr, v);
758 let iv = C_integral(cx.int_type(), discr.0, false);
759 let s = adt::is_discr_signed(&repr) as Bool;
760 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
762 (CastTy::Int(_), CastTy::Int(_)) => {
763 let s = t_expr.is_signed() as Bool;
764 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
766 (CastTy::Int(_), CastTy::Float) => {
767 if t_expr.is_signed() {
768 llvm::LLVMConstSIToFP(v, llty.to_ref())
770 llvm::LLVMConstUIToFP(v, llty.to_ref())
773 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
774 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
775 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
776 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
777 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
780 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
781 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
782 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
783 llvm::LLVMConstPtrToInt(v, llty.to_ref())
786 cx.sess().impossible_case(e.span,
787 "bad combination of types for cast")
789 } } // unsafe { match ( ... ) {
791 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
792 // If this is the address of some static, then we need to return
793 // the actual address of the static itself (short circuit the rest
798 hir::ExprBlock(ref blk) => {
799 if let Some(ref sub) = blk.expr {
808 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
809 if let Some(Def::Static(def_id, _)) = opt_def {
810 get_static(cx, def_id).val
812 // If this isn't the address of a static, then keep going through
813 // normal constant evaluation.
814 let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?;
815 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
818 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
819 let (v, ty) = const_expr(cx, &sub, param_substs, fn_args, trueconst)?;
820 addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
822 hir::ExprTup(ref es) => {
823 let repr = adt::represent_type(cx, ety);
824 let vals = map_list(&es[..])?;
825 adt::trans_const(cx, &repr, Disr(0), &vals[..])
827 hir::ExprStruct(_, ref fs, ref base_opt) => {
828 let repr = adt::represent_type(cx, ety);
830 let base_val = match *base_opt {
831 Some(ref base) => Some(const_expr(
841 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
842 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
843 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
844 (Some(ref f), _) => {
845 const_expr(cx, &f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l)
847 (_, Some((bv, _))) => Ok(adt::const_get_field(cx, &repr, bv, discr, ix)),
848 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
851 .collect::<Vec<Result<_, ConstEvalFailure>>>()
853 .collect::<Result<Vec<_>,ConstEvalFailure>>();
858 adt::trans_const(cx, &repr, discr, &cs[..])
861 hir::ExprVec(ref es) => {
862 let unit_ty = ety.sequence_element_type(cx.tcx());
863 let llunitty = type_of::type_of(cx, unit_ty);
872 .collect::<Vec<Result<_, ConstEvalFailure>>>()
874 .collect::<Result<Vec<_>, ConstEvalFailure>>();
876 // If the vector contains enums, an LLVM array won't work.
877 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
878 C_struct(cx, &vs[..], false)
880 C_array(llunitty, &vs[..])
883 hir::ExprRepeat(ref elem, ref count) => {
884 let unit_ty = ety.sequence_element_type(cx.tcx());
885 let llunitty = type_of::type_of(cx, unit_ty);
886 let n = cx.tcx().eval_repeat_count(count);
887 let unit_val = const_expr(cx, &elem, param_substs, fn_args, trueconst)?.0;
888 let vs = vec![unit_val; n];
889 if val_ty(unit_val) != llunitty {
890 C_struct(cx, &vs[..], false)
892 C_array(llunitty, &vs[..])
895 hir::ExprPath(..) => {
896 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
898 Def::Local(_, id) => {
899 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
902 cx.sess().span_bug(e.span, "const fn argument not found")
905 Def::Fn(..) | Def::Method(..) => C_nil(cx),
906 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
907 load_const(cx, get_const_val(cx, def_id, e, param_substs)?,
910 Def::Variant(enum_did, variant_did) => {
911 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
913 ty::VariantKind::Unit => {
914 let repr = adt::represent_type(cx, ety);
915 adt::trans_const(cx, &repr, Disr::from(vinfo.disr_val), &[])
917 ty::VariantKind::Tuple => C_nil(cx),
918 ty::VariantKind::Struct => {
919 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
923 // Unit struct or ctor.
924 Def::Struct(..) => C_null(type_of::type_of(cx, ety)),
926 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
931 hir::ExprCall(ref callee, ref args) => {
932 let mut callee = &**callee;
934 callee = match callee.node {
935 hir::ExprBlock(ref block) => match block.expr {
936 Some(ref tail) => &tail,
942 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
943 let arg_vals = map_list(args)?;
945 Def::Fn(did) | Def::Method(did) => {
949 cx.tcx().node_id_item_substs(callee.id).substs,
957 C_vector(&arg_vals[..])
959 let repr = adt::represent_type(cx, ety);
960 adt::trans_const(cx, &repr, Disr(0), &arg_vals[..])
963 Def::Variant(enum_did, variant_did) => {
964 let repr = adt::represent_type(cx, ety);
965 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
968 Disr::from(vinfo.disr_val),
971 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
974 hir::ExprMethodCall(_, _, ref args) => {
975 let arg_vals = map_list(args)?;
976 let method_call = ty::MethodCall::expr(e.id);
977 let method = cx.tcx().tables.borrow().method_map[&method_call];
978 const_fn_call(cx, method.def_id, method.substs.clone(),
979 &arg_vals, param_substs, trueconst)?
981 hir::ExprType(ref e, _) => const_expr(cx, &e, param_substs, fn_args, trueconst)?.0,
982 hir::ExprBlock(ref block) => {
984 Some(ref expr) => const_expr(
994 hir::ExprClosure(_, ref decl, ref body) => {
996 ty::TyClosure(def_id, ref substs) => {
997 closure::trans_closure_expr(closure::Dest::Ignore(cx),
1007 &format!("bad type for closure expr: {:?}", ety))
1009 C_null(type_of::type_of(cx, ety))
1011 _ => cx.sess().span_bug(e.span,
1012 "bad constant expression type in consts::const_expr"),
1016 pub fn get_static<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, def_id: DefId)
1017 -> Datum<'tcx, Lvalue> {
1018 let ty = ccx.tcx().lookup_item_type(def_id).ty;
1020 let instance = Instance::mono(ccx.tcx(), def_id);
1021 if let Some(&g) = ccx.instances().borrow().get(&instance) {
1022 return Datum::new(g, ty, Lvalue::new("static"));
1025 let g = if let Some(id) = ccx.tcx().map.as_local_node_id(def_id) {
1026 let llty = type_of::type_of(ccx, ty);
1027 match ccx.tcx().map.get(id) {
1028 hir_map::NodeItem(&hir::Item {
1029 ref attrs, span, node: hir::ItemStatic(..), ..
1031 // If this static came from an external crate, then
1032 // we need to get the symbol from metadata instead of
1033 // using the current crate's name/version
1034 // information in the hash of the symbol
1035 let sym = exported_name(ccx, id, ty, attrs);
1036 debug!("making {}", sym);
1038 // Create the global before evaluating the initializer;
1039 // this is necessary to allow recursive statics.
1040 let g = declare::define_global(ccx, &sym, llty).unwrap_or_else(|| {
1041 ccx.sess().span_fatal(span,
1042 &format!("symbol `{}` is already defined", sym))
1045 ccx.item_symbols().borrow_mut().insert(id, sym);
1049 hir_map::NodeForeignItem(&hir::ForeignItem {
1050 ref attrs, name, span, node: hir::ForeignItemStatic(..), ..
1052 let ident = imported_name(name, attrs);
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, &ident, llty2);
1075 llvm::SetLinkage(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(&ident);
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", ident))
1089 llvm::SetLinkage(g2, llvm::InternalLinkage);
1090 llvm::LLVMSetInitializer(g2, g1);
1094 // Generate an external declaration.
1095 declare::declare_global(ccx, &ident, llty)
1099 if attr.check_name("thread_local") {
1100 llvm::set_thread_local(g, true);
1107 item => unreachable!("get_static: expected static, found {:?}", item)
1110 // FIXME(nagisa): perhaps the map of externs could be offloaded to llvm somehow?
1111 // FIXME(nagisa): investigate whether it can be changed into define_global
1112 let name = ccx.sess().cstore.item_symbol(def_id);
1113 let g = declare::declare_global(ccx, &name, type_of::type_of(ccx, ty));
1114 // Thread-local statics in some other crate need to *always* be linked
1115 // against in a thread-local fashion, so we need to be sure to apply the
1116 // thread-local attribute locally if it was present remotely. If we
1117 // don't do this then linker errors can be generated where the linker
1118 // complains that one object files has a thread local version of the
1119 // symbol and another one doesn't.
1120 for attr in ccx.tcx().get_attrs(def_id).iter() {
1121 if attr.check_name("thread_local") {
1122 llvm::set_thread_local(g, true);
1125 if ccx.use_dll_storage_attrs() {
1126 llvm::SetDLLStorageClass(g, llvm::DLLImportStorageClass);
1131 ccx.instances().borrow_mut().insert(instance, g);
1132 Datum::new(g, ty, Lvalue::new("static"))
1135 pub fn trans_static(ccx: &CrateContext,
1139 attrs: &[ast::Attribute])
1140 -> Result<ValueRef, ConstEvalErr> {
1142 if collector::collecting_debug_information(ccx) {
1143 ccx.record_translation_item_as_generated(TransItem::Static(id));
1147 let _icx = push_ctxt("trans_static");
1148 let def_id = ccx.tcx().map.local_def_id(id);
1149 let datum = get_static(ccx, def_id);
1151 let empty_substs = ccx.tcx().mk_substs(Substs::empty());
1152 let (v, _) = const_expr(
1158 ).map_err(|e| e.into_inner())?;
1160 // boolean SSA values are i1, but they have to be stored in i8 slots,
1161 // otherwise some LLVM optimization passes don't work as expected
1162 let mut val_llty = val_ty(v);
1163 let v = if val_llty == Type::i1(ccx) {
1164 val_llty = Type::i8(ccx);
1165 llvm::LLVMConstZExt(v, val_llty.to_ref())
1170 let llty = type_of::type_of(ccx, datum.ty);
1171 let g = if val_llty == llty {
1174 // If we created the global with the wrong type,
1175 // correct the type.
1176 let empty_string = CString::new("").unwrap();
1177 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(datum.val));
1178 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
1179 llvm::LLVMSetValueName(datum.val, empty_string.as_ptr());
1180 let new_g = llvm::LLVMGetOrInsertGlobal(
1181 ccx.llmod(), name_string.as_ptr(), val_llty.to_ref());
1182 // To avoid breaking any invariants, we leave around the old
1183 // global for the moment; we'll replace all references to it
1184 // with the new global later. (See base::trans_crate.)
1185 ccx.statics_to_rauw().borrow_mut().push((datum.val, new_g));
1188 llvm::LLVMSetAlignment(g, type_of::align_of(ccx, datum.ty));
1189 llvm::LLVMSetInitializer(g, v);
1191 // As an optimization, all shared statics which do not have interior
1192 // mutability are placed into read-only memory.
1193 if m != hir::MutMutable {
1194 let tcontents = datum.ty.type_contents(ccx.tcx());
1195 if !tcontents.interior_unsafe() {
1196 llvm::LLVMSetGlobalConstant(g, llvm::True);
1200 debuginfo::create_global_var_metadata(ccx, id, g);
1202 if attr::contains_name(attrs,
1204 llvm::set_thread_local(g, true);