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};
28 use middle::def_id::DefId;
29 use trans::{adt, closure, debuginfo, expr, inline, machine};
30 use trans::base::{self, push_ctxt};
31 use trans::collector::{self, TransItem};
32 use trans::common::{self, type_is_sized, ExprOrMethodCall, node_id_substs, C_nil, const_get_elt};
33 use trans::common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty};
34 use trans::common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint};
35 use trans::common::{type_is_fat_ptr, Field, C_vector, C_array, C_null, ExprId, MethodCallKey};
37 use trans::monomorphize;
38 use trans::type_::Type;
41 use middle::subst::Substs;
42 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
43 use middle::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer};
44 use middle::ty::{self, Ty};
45 use middle::ty::cast::{CastTy,IntTy};
46 use util::nodemap::NodeMap;
50 use std::ffi::{CStr, CString};
53 use syntax::ast::{self, LitKind};
55 use syntax::parse::token;
58 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
60 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit)
62 let _icx = push_ctxt("trans_lit");
63 debug!("const_lit: {:?}", lit);
65 LitKind::Byte(b) => C_integral(Type::uint_from_ty(cx, ast::UintTy::U8), b as u64, false),
66 LitKind::Char(i) => C_integral(Type::char(cx), i as u64, false),
67 LitKind::Int(i, ast::LitIntType::Signed(t)) => {
68 C_integral(Type::int_from_ty(cx, t), i, true)
70 LitKind::Int(u, ast::LitIntType::Unsigned(t)) => {
71 C_integral(Type::uint_from_ty(cx, t), u, false)
73 LitKind::Int(i, ast::LitIntType::Unsuffixed) => {
74 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
75 match lit_int_ty.sty {
77 C_integral(Type::int_from_ty(cx, t), i as u64, true)
80 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
82 _ => cx.sess().span_bug(lit.span,
83 &format!("integer literal has type {:?} (expected int \
88 LitKind::Float(ref fs, t) => {
89 C_floating(&fs, Type::float_from_ty(cx, t))
91 LitKind::FloatUnsuffixed(ref fs) => {
92 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
93 match lit_float_ty.sty {
95 C_floating(&fs, Type::float_from_ty(cx, t))
98 cx.sess().span_bug(lit.span,
99 "floating point literal doesn't have the right type");
103 LitKind::Bool(b) => C_bool(cx, b),
104 LitKind::Str(ref s, _) => C_str_slice(cx, (*s).clone()),
105 LitKind::ByteStr(ref data) => {
106 addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str")
111 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
113 llvm::LLVMConstPointerCast(val, ty.to_ref())
117 fn addr_of_mut(ccx: &CrateContext,
119 align: machine::llalign,
123 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
124 // counter? Also most other uses of gensym in trans.
125 let gsym = token::gensym("_");
126 let name = format!("{}{}", kind, gsym.0);
127 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
128 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
130 llvm::LLVMSetInitializer(gv, cv);
131 llvm::LLVMSetAlignment(gv, align);
132 SetLinkage(gv, InternalLinkage);
133 SetUnnamedAddr(gv, true);
138 pub fn addr_of(ccx: &CrateContext,
140 align: machine::llalign,
143 match ccx.const_globals().borrow().get(&cv) {
146 // Upgrade the alignment in cases where the same constant is used with different
147 // alignment requirements
148 if align > llvm::LLVMGetAlignment(gv) {
149 llvm::LLVMSetAlignment(gv, align);
156 let gv = addr_of_mut(ccx, cv, align, kind);
158 llvm::LLVMSetGlobalConstant(gv, True);
160 ccx.const_globals().borrow_mut().insert(cv, gv);
164 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
165 let v = match cx.const_unsized().borrow().get(&v) {
170 llvm::LLVMGetInitializer(v)
174 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
177 -> (ValueRef, Ty<'tcx>) {
178 match ty.builtin_deref(true, ty::NoPreference) {
180 if type_is_sized(cx.tcx(), mt.ty) {
181 (const_deref_ptr(cx, v), mt.ty)
183 // Derefing a fat pointer does not change the representation,
184 // just the type to the unsized contents.
189 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
195 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
196 node: ExprOrMethodCall,
198 arg_vals: &[ValueRef],
199 param_substs: &'tcx Substs<'tcx>,
200 trueconst: TrueConst) -> Result<ValueRef, ConstEvalFailure> {
201 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
202 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
204 let args = &fn_like.decl().inputs;
205 assert_eq!(args.len(), arg_vals.len());
207 let arg_ids = args.iter().map(|arg| arg.pat.id);
208 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
210 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
211 match fn_like.body().expr {
213 const_expr(ccx, &expr, substs, Some(&fn_args), trueconst).map(|(res, _)| res)
215 None => Ok(C_nil(ccx)),
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 def_id = inline::maybe_instantiate_inline(ccx, def_id);
226 if def_id.krate != LOCAL_CRATE {
227 ccx.sess().span_bug(ref_expr.span,
228 "cross crate constant could not be inlined");
231 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id), Some(param_substs)) {
232 Some(ref expr) => 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::trans_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 try!(const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst))
321 try!(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 = try!(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) => {
354 // FIXME(#19925) once fn item types are
355 // zero-sized, we'll need to do something here
357 Some(AdjustUnsafeFnPointer) | Some(AdjustMutToConstPointer) => {
358 // purely a type-level thing
360 Some(AdjustDerefRef(adj)) => {
362 // Save the last autoderef in case we can avoid it.
363 if adj.autoderefs > 0 {
364 for _ in 0..adj.autoderefs-1 {
365 let (dv, dt) = const_deref(cx, llconst, ty);
371 if adj.autoref.is_some() {
372 if adj.autoderefs == 0 {
373 // Don't copy data to do a deref+ref
374 // (i.e., skip the last auto-deref).
375 llconst = addr_of(cx, llconst, type_of::align_of(cx, ty), "autoref");
376 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
379 let (dv, dt) = const_deref(cx, llconst, ty);
382 // If we derefed a fat pointer then we will have an
383 // open type here. So we need to update the type with
384 // the one returned from const_deref.
388 if let Some(target) = adj.unsize {
389 let target = monomorphize::apply_param_substs(cx.tcx(),
393 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
394 .expect("consts: unsizing got non-pointer type").ty;
395 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
396 // Normally, the source is a thin pointer and we are
397 // adding extra info to make a fat pointer. The exception
398 // is when we are upcasting an existing object fat pointer
399 // to use a different vtable. In that case, we want to
400 // load out the original data pointer so we can repackage
402 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
403 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
408 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
409 .expect("consts: unsizing got non-pointer target type").ty;
410 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
411 let base = ptrcast(base, ptr_ty);
412 let info = base::unsized_info(cx, pointee_ty, unsized_ty,
413 old_info, param_substs);
415 if old_info.is_none() {
416 let prev_const = cx.const_unsized().borrow_mut()
417 .insert(base, llconst);
418 assert!(prev_const.is_none() || prev_const == Some(llconst));
420 assert_eq!(abi::FAT_PTR_ADDR, 0);
421 assert_eq!(abi::FAT_PTR_EXTRA, 1);
422 llconst = C_struct(cx, &[base, info], false);
428 let llty = type_of::sizing_type_of(cx, ety_adjusted);
429 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
430 let tsize = machine::llsize_of_alloc(cx, llty);
432 cx.sess().abort_if_errors();
434 // FIXME these values could use some context
435 llvm::LLVMDumpValue(llconst);
436 llvm::LLVMDumpValue(C_undef(llty));
438 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
442 Ok((llconst, ety_adjusted))
445 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
446 te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
447 // The only kind of unary expression that we check for validity
448 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
449 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
451 // An unfortunate special case: we parse e.g. -128 as a
452 // negation of the literal 128, which means if we're expecting
453 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
454 // 128 will have already overflowed to -128, and so then the
455 // constant evaluator thinks we're trying to negate -128.
457 // Catch this up front by looking for ExprLit directly,
458 // and just accepting it.
459 if let hir::ExprLit(_) = inner_e.node { return Ok(()); }
461 let result = match t.sty {
462 ty::TyInt(int_type) => {
463 let input = match const_to_opt_int(te) {
465 None => return Ok(()),
467 const_int_checked_neg(
468 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
470 ty::TyUint(uint_type) => {
471 let input = match const_to_opt_uint(te) {
473 None => return Ok(()),
475 const_uint_checked_neg(
476 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
480 const_err(cx, e, result, trueconst)
486 fn const_err(cx: &CrateContext,
488 result: Result<ConstVal, ConstEvalErr>,
489 trueconst: TrueConst)
490 -> Result<(), ConstEvalFailure> {
491 match (result, trueconst) {
493 // We do not actually care about a successful result.
496 (Err(err), TrueConst::Yes) => {
497 cx.tcx().sess.span_err(e.span, &err.description());
498 Err(Compiletime(err))
500 (Err(err), TrueConst::No) => {
501 cx.tcx().sess.span_warn(e.span, &err.description());
507 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
508 te1: ValueRef, te2: ValueRef,
509 trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
510 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { unreachable!() };
512 let result = match t.sty {
513 ty::TyInt(int_type) => {
514 let (lhs, rhs) = match (const_to_opt_int(te1),
515 const_to_opt_int(te2)) {
516 (Some(v1), Some(v2)) => (v1, v2),
520 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
522 hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
523 hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
524 hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
525 hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
526 hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
527 hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
528 hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
532 ty::TyUint(uint_type) => {
533 let (lhs, rhs) = match (const_to_opt_uint(te1),
534 const_to_opt_uint(te2)) {
535 (Some(v1), Some(v2)) => (v1, v2),
539 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
541 hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
542 hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
543 hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
544 hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
545 hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
546 hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
547 hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
553 const_err(cx, e, result, trueconst)
556 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
559 param_substs: &'tcx Substs<'tcx>,
561 trueconst: TrueConst)
562 -> Result<ValueRef, ConstEvalFailure>
564 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
569 let map_list = |exprs: &[P<hir::Expr>]| -> Result<Vec<ValueRef>, ConstEvalFailure> {
571 .map(|e| const_expr(cx, &e, param_substs, fn_args, trueconst).map(|(l, _)| l))
572 .collect::<Vec<Result<ValueRef, ConstEvalFailure>>>()
575 // this dance is necessary to eagerly run const_expr so all errors are reported
577 let _icx = push_ctxt("const_expr");
579 hir::ExprLit(ref lit) => const_lit(cx, e, &lit),
580 hir::ExprBinary(b, ref e1, ref e2) => {
581 /* Neither type is bottom, and we expect them to be unified
582 * already, so the following is safe. */
583 let (te1, ty) = try!(const_expr(cx, &e1, param_substs, fn_args, trueconst));
584 debug!("const_expr_unadjusted: te1={}, ty={:?}",
585 cx.tn().val_to_string(te1),
587 assert!(!ty.is_simd());
588 let is_float = ty.is_fp();
589 let signed = ty.is_signed();
591 let (te2, _) = try!(const_expr(cx, &e2, param_substs, fn_args, trueconst));
593 try!(check_binary_expr_validity(cx, e, ty, te1, te2, trueconst));
595 unsafe { match b.node {
596 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
597 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
599 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
600 hir::BiSub => llvm::LLVMConstSub(te1, te2),
602 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
603 hir::BiMul => llvm::LLVMConstMul(te1, te2),
605 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
606 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
607 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
609 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
610 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
611 hir::BiRem => llvm::LLVMConstURem(te1, te2),
613 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
614 hir::BiOr => llvm::LLVMConstOr(te1, te2),
615 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
616 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
617 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
619 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
620 llvm::LLVMConstShl(te1, te2)
623 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
624 if signed { llvm::LLVMConstAShr(te1, te2) }
625 else { llvm::LLVMConstLShr(te1, te2) }
627 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
629 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
630 ConstFCmp(cmp, te1, te2)
632 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
633 ConstICmp(cmp, te1, te2)
636 } } // unsafe { match b.node {
638 hir::ExprUnary(u, ref inner_e) => {
639 let (te, ty) = try!(const_expr(cx, &inner_e, param_substs, fn_args, trueconst));
641 try!(check_unary_expr_validity(cx, e, ty, te, trueconst));
643 let is_float = ty.is_fp();
645 hir::UnDeref => const_deref(cx, te, ty).0,
646 hir::UnNot => llvm::LLVMConstNot(te),
647 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
648 hir::UnNeg => llvm::LLVMConstNeg(te),
651 hir::ExprField(ref base, field) => {
652 let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
653 let brepr = adt::represent_type(cx, bt);
654 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
655 let ix = vinfo.field_index(field.node);
656 adt::const_get_field(cx, &brepr, bv, vinfo.discr, ix)
658 hir::ExprTupField(ref base, idx) => {
659 let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
660 let brepr = adt::represent_type(cx, bt);
661 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
662 adt::const_get_field(cx, &brepr, bv, vinfo.discr, idx.node)
664 hir::ExprIndex(ref base, ref index) => {
665 let (bv, bt) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
666 let iv = try!(const_expr(cx, &index, param_substs, fn_args, TrueConst::Yes)).0;
667 let iv = if let Some(iv) = const_to_opt_uint(iv) {
670 cx.sess().span_bug(index.span, "index is not an integer-constant expression");
672 let (arr, len) = match bt.sty {
673 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
674 ty::TySlice(_) | ty::TyStr => {
675 let e1 = const_get_elt(cx, bv, &[0]);
676 (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1]))
678 ty::TyRef(_, mt) => match mt.ty.sty {
679 ty::TyArray(_, u) => {
680 (const_deref_ptr(cx, bv), C_uint(cx, u))
682 _ => cx.sess().span_bug(base.span,
683 &format!("index-expr base must be a vector \
684 or string type, found {:?}",
687 _ => cx.sess().span_bug(base.span,
688 &format!("index-expr base must be a vector \
689 or string type, found {:?}",
693 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
694 let len = match bt.sty {
695 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
705 // FIXME #3170: report this earlier on in the const-eval
706 // pass. Reporting here is a bit late.
707 span_err!(cx.sess(), e.span, E0515,
708 "const index-expr is out of bounds");
709 C_undef(val_ty(arr).element_type())
711 const_get_elt(cx, arr, &[iv as c_uint])
714 hir::ExprCast(ref base, _) => {
716 let llty = type_of::type_of(cx, t_cast);
717 let (v, t_expr) = try!(const_expr(cx, &base, param_substs, fn_args, trueconst));
718 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
719 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
722 if type_is_fat_ptr(cx.tcx(), t_expr) {
723 // Fat pointer casts.
725 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
726 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
727 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
729 if type_is_fat_ptr(cx.tcx(), t_cast) {
730 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
731 return Ok(C_struct(cx, &[addr, info], false))
737 CastTy::from_ty(t_expr).expect("bad input type for cast"),
738 CastTy::from_ty(t_cast).expect("bad output type for cast"),
740 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
741 let repr = adt::represent_type(cx, t_expr);
742 let discr = adt::const_get_discrim(cx, &repr, v);
743 let iv = C_integral(cx.int_type(), discr.0, false);
744 let s = adt::is_discr_signed(&repr) as Bool;
745 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
747 (CastTy::Int(_), CastTy::Int(_)) => {
748 let s = t_expr.is_signed() as Bool;
749 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
751 (CastTy::Int(_), CastTy::Float) => {
752 if t_expr.is_signed() {
753 llvm::LLVMConstSIToFP(v, llty.to_ref())
755 llvm::LLVMConstUIToFP(v, llty.to_ref())
758 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
759 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
760 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
761 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
762 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
765 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
766 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
767 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
768 llvm::LLVMConstPtrToInt(v, llty.to_ref())
771 cx.sess().impossible_case(e.span,
772 "bad combination of types for cast")
774 } } // unsafe { match ( ... ) {
776 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
777 // If this is the address of some static, then we need to return
778 // the actual address of the static itself (short circuit the rest
783 hir::ExprBlock(ref blk) => {
784 if let Some(ref sub) = blk.expr {
793 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
794 if let Some(Def::Static(def_id, _)) = opt_def {
795 common::get_static_val(cx, def_id, ety)
797 // If this isn't the address of a static, then keep going through
798 // normal constant evaluation.
799 let (v, ty) = try!(const_expr(cx, &sub, param_substs, fn_args, trueconst));
800 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
803 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
804 let (v, ty) = try!(const_expr(cx, &sub, param_substs, fn_args, trueconst));
805 addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
807 hir::ExprTup(ref es) => {
808 let repr = adt::represent_type(cx, ety);
809 let vals = try!(map_list(&es[..]));
810 adt::trans_const(cx, &repr, Disr(0), &vals[..])
812 hir::ExprStruct(_, ref fs, ref base_opt) => {
813 let repr = adt::represent_type(cx, ety);
815 let base_val = match *base_opt {
816 Some(ref base) => Some(try!(const_expr(
826 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
827 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
828 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
829 (Some(ref f), _) => {
830 const_expr(cx, &f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l)
832 (_, Some((bv, _))) => Ok(adt::const_get_field(cx, &repr, bv, discr, ix)),
833 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
836 .collect::<Vec<Result<_, ConstEvalFailure>>>()
838 .collect::<Result<Vec<_>,ConstEvalFailure>>();
843 adt::trans_const(cx, &repr, discr, &cs[..])
846 hir::ExprVec(ref es) => {
847 let unit_ty = ety.sequence_element_type(cx.tcx());
848 let llunitty = type_of::type_of(cx, unit_ty);
857 .collect::<Vec<Result<_, ConstEvalFailure>>>()
859 .collect::<Result<Vec<_>, ConstEvalFailure>>();
861 // If the vector contains enums, an LLVM array won't work.
862 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
863 C_struct(cx, &vs[..], false)
865 C_array(llunitty, &vs[..])
868 hir::ExprRepeat(ref elem, ref count) => {
869 let unit_ty = ety.sequence_element_type(cx.tcx());
870 let llunitty = type_of::type_of(cx, unit_ty);
871 let n = cx.tcx().eval_repeat_count(count);
872 let unit_val = try!(const_expr(cx, &elem, param_substs, fn_args, trueconst)).0;
873 let vs = vec![unit_val; n];
874 if val_ty(unit_val) != llunitty {
875 C_struct(cx, &vs[..], false)
877 C_array(llunitty, &vs[..])
880 hir::ExprPath(..) => {
881 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
883 Def::Local(_, id) => {
884 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
887 cx.sess().span_bug(e.span, "const fn argument not found")
890 Def::Fn(..) | Def::Method(..) => {
891 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
893 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
894 const_deref_ptr(cx, try!(get_const_val(cx, def_id, e, param_substs)))
896 Def::Variant(enum_did, variant_did) => {
897 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
899 ty::VariantKind::Unit => {
900 let repr = adt::represent_type(cx, ety);
901 adt::trans_const(cx, &repr, Disr::from(vinfo.disr_val), &[])
903 ty::VariantKind::Tuple => {
904 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
906 ty::VariantKind::Struct => {
907 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
912 if let ty::TyBareFn(..) = ety.sty {
914 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
917 C_null(type_of::type_of(cx, ety))
921 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
926 hir::ExprCall(ref callee, ref args) => {
927 let mut callee = &**callee;
929 callee = match callee.node {
930 hir::ExprBlock(ref block) => match block.expr {
931 Some(ref tail) => &tail,
937 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
938 let arg_vals = try!(map_list(args));
940 Def::Fn(did) | Def::Method(did) => {
952 C_vector(&arg_vals[..])
954 let repr = adt::represent_type(cx, ety);
955 adt::trans_const(cx, &repr, Disr(0), &arg_vals[..])
958 Def::Variant(enum_did, variant_did) => {
959 let repr = adt::represent_type(cx, ety);
960 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
963 Disr::from(vinfo.disr_val),
966 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
969 hir::ExprMethodCall(_, _, ref args) => {
970 let arg_vals = try!(map_list(args));
971 let method_call = ty::MethodCall::expr(e.id);
972 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
973 try!(const_fn_call(cx, MethodCallKey(method_call),
974 method_did, &arg_vals, param_substs, trueconst))
976 hir::ExprType(ref e, _) => try!(const_expr(cx, &e, param_substs, fn_args, trueconst)).0,
977 hir::ExprBlock(ref block) => {
979 Some(ref expr) => try!(const_expr(
989 hir::ExprClosure(_, ref decl, ref body) => {
991 ty::TyClosure(def_id, ref substs) => {
992 closure::trans_closure_expr(closure::Dest::Ignore(cx),
1003 &format!("bad type for closure expr: {:?}", ety))
1005 C_null(type_of::type_of(cx, ety))
1007 _ => cx.sess().span_bug(e.span,
1008 "bad constant expression type in consts::const_expr"),
1012 pub fn trans_static(ccx: &CrateContext,
1016 attrs: &[ast::Attribute])
1017 -> Result<ValueRef, ConstEvalErr> {
1019 if collector::collecting_debug_information(ccx) {
1020 ccx.record_translation_item_as_generated(TransItem::Static(id));
1024 let _icx = push_ctxt("trans_static");
1025 let g = base::get_item_val(ccx, id);
1027 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
1028 let (v, _) = try!(const_expr(
1034 ).map_err(|e| e.into_inner()));
1036 // boolean SSA values are i1, but they have to be stored in i8 slots,
1037 // otherwise some LLVM optimization passes don't work as expected
1038 let mut val_llty = llvm::LLVMTypeOf(v);
1039 let v = if val_llty == Type::i1(ccx).to_ref() {
1040 val_llty = Type::i8(ccx).to_ref();
1041 llvm::LLVMConstZExt(v, val_llty)
1046 let ty = ccx.tcx().node_id_to_type(id);
1047 let llty = type_of::type_of(ccx, ty);
1048 let g = if val_llty == llty.to_ref() {
1051 // If we created the global with the wrong type,
1052 // correct the type.
1053 let empty_string = CString::new("").unwrap();
1054 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
1055 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
1056 llvm::LLVMSetValueName(g, empty_string.as_ptr());
1057 let new_g = llvm::LLVMGetOrInsertGlobal(
1058 ccx.llmod(), name_string.as_ptr(), val_llty);
1059 // To avoid breaking any invariants, we leave around the old
1060 // global for the moment; we'll replace all references to it
1061 // with the new global later. (See base::trans_crate.)
1062 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
1065 llvm::LLVMSetAlignment(g, type_of::align_of(ccx, ty));
1066 llvm::LLVMSetInitializer(g, v);
1068 // As an optimization, all shared statics which do not have interior
1069 // mutability are placed into read-only memory.
1070 if m != hir::MutMutable {
1071 let tcontents = ty.type_contents(ccx.tcx());
1072 if !tcontents.interior_unsafe() {
1073 llvm::LLVMSetGlobalConstant(g, llvm::True);
1077 debuginfo::create_global_var_metadata(ccx, id, g);
1079 if attr::contains_name(attrs,
1081 llvm::set_thread_local(g, true);