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 metadata::cstore::LOCAL_CRATE;
17 use middle::{check_const, def};
18 use middle::const_eval::{self, ConstVal};
19 use middle::const_eval::{const_int_checked_neg, const_uint_checked_neg};
20 use middle::const_eval::{const_int_checked_add, const_uint_checked_add};
21 use middle::const_eval::{const_int_checked_sub, const_uint_checked_sub};
22 use middle::const_eval::{const_int_checked_mul, const_uint_checked_mul};
23 use middle::const_eval::{const_int_checked_div, const_uint_checked_div};
24 use middle::const_eval::{const_int_checked_rem, const_uint_checked_rem};
25 use middle::const_eval::{const_int_checked_shl, const_uint_checked_shl};
26 use middle::const_eval::{const_int_checked_shr, const_uint_checked_shr};
27 use middle::const_eval::EvalHint::ExprTypeChecked;
28 use middle::const_eval::eval_const_expr_partial;
29 use middle::def_id::DefId;
30 use trans::{adt, closure, debuginfo, expr, inline, machine};
31 use trans::base::{self, push_ctxt};
34 use trans::monomorphize;
35 use trans::type_::Type;
37 use middle::subst::Substs;
38 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
39 use middle::ty::adjustment::AdjustUnsafeFnPointer;
40 use middle::ty::{self, Ty};
41 use middle::ty::cast::{CastTy,IntTy};
42 use util::nodemap::NodeMap;
46 use std::ffi::{CStr, CString};
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 ast::LitByte(b) => C_integral(Type::uint_from_ty(cx, ast::TyU8), b as u64, false),
61 ast::LitChar(i) => C_integral(Type::char(cx), i as u64, false),
62 ast::LitInt(i, ast::SignedIntLit(t, _)) => {
63 C_integral(Type::int_from_ty(cx, t), i, true)
65 ast::LitInt(u, ast::UnsignedIntLit(t)) => {
66 C_integral(Type::uint_from_ty(cx, t), u, false)
68 ast::LitInt(i, ast::UnsuffixedIntLit(_)) => {
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 ast::LitFloat(ref fs, t) => {
84 C_floating(&fs, Type::float_from_ty(cx, t))
86 ast::LitFloatUnsuffixed(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 ast::LitBool(b) => C_bool(cx, b),
99 ast::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()),
100 ast::LitByteStr(ref data) => {
101 addr_of(cx, C_bytes(cx, &data[..]), "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,
117 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
118 // counter? Also most other uses of gensym in trans.
119 let gsym = token::gensym("_");
120 let name = format!("{}{}", kind, gsym.0);
121 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
122 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
124 llvm::LLVMSetInitializer(gv, cv);
125 SetLinkage(gv, InternalLinkage);
126 SetUnnamedAddr(gv, true);
131 pub fn addr_of(ccx: &CrateContext,
135 match ccx.const_globals().borrow().get(&cv) {
136 Some(&gv) => return gv,
139 let gv = addr_of_mut(ccx, cv, kind);
141 llvm::LLVMSetGlobalConstant(gv, True);
143 ccx.const_globals().borrow_mut().insert(cv, gv);
147 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
148 let v = match cx.const_unsized().borrow().get(&v) {
153 llvm::LLVMGetInitializer(v)
157 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
160 -> (ValueRef, Ty<'tcx>) {
161 match ty.builtin_deref(true, ty::NoPreference) {
163 if type_is_sized(cx.tcx(), mt.ty) {
164 (const_deref_ptr(cx, v), mt.ty)
166 // Derefing a fat pointer does not change the representation,
167 // just the type to the unsized contents.
172 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
178 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
179 node: ExprOrMethodCall,
181 arg_vals: &[ValueRef],
182 param_substs: &'tcx Substs<'tcx>) -> ValueRef {
183 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
184 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
186 let args = &fn_like.decl().inputs;
187 assert_eq!(args.len(), arg_vals.len());
189 let arg_ids = args.iter().map(|arg| arg.pat.id);
190 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
192 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
193 match fn_like.body().expr {
195 const_expr(ccx, &**expr, substs, Some(&fn_args)).0
201 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
203 ref_expr: &hir::Expr)
205 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
207 if def_id.krate != LOCAL_CRATE {
208 ccx.sess().span_bug(ref_expr.span,
209 "cross crate constant could not be inlined");
212 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id)) {
213 Some(ref expr) => expr,
215 ccx.sess().span_bug(ref_expr.span, "constant item not found")
220 fn get_const_val(ccx: &CrateContext,
222 ref_expr: &hir::Expr) -> ValueRef {
223 let expr = get_const_expr(ccx, def_id, ref_expr);
224 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
225 get_const_expr_as_global(ccx, expr, check_const::ConstQualif::empty(), empty_substs)
228 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
230 qualif: check_const::ConstQualif,
231 param_substs: &'tcx Substs<'tcx>)
233 debug!("get_const_expr_as_global: {:?}", expr.id);
234 // Special-case constants to cache a common global for all uses.
236 hir::ExprPath(..) => {
237 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
239 def::DefConst(def_id) | def::DefAssociatedConst(def_id) => {
240 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
241 debug!("get_const_expr_as_global ({:?}): found const {:?}",
243 return get_const_val(ccx, def_id, expr);
252 let key = (expr.id, param_substs);
253 match ccx.const_values().borrow().get(&key) {
254 Some(&val) => return val,
257 let val = if qualif.intersects(check_const::ConstQualif::NON_STATIC_BORROWS) {
258 // Avoid autorefs as they would create global instead of stack
259 // references, even when only the latter are correct.
260 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
261 &ccx.tcx().expr_ty(expr));
262 const_expr_unadjusted(ccx, expr, ty, param_substs, None)
264 const_expr(ccx, expr, param_substs, None).0
267 // boolean SSA values are i1, but they have to be stored in i8 slots,
268 // otherwise some LLVM optimization passes don't work as expected
270 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
271 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
277 let lvalue = addr_of(ccx, val, "const");
278 ccx.const_values().borrow_mut().insert(key, lvalue);
282 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
284 param_substs: &'tcx Substs<'tcx>,
286 -> (ValueRef, Ty<'tcx>) {
287 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
288 &cx.tcx().expr_ty(e));
289 let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args);
290 let mut llconst = llconst;
291 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
292 &cx.tcx().expr_ty_adjusted(e));
293 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
295 Some(AdjustReifyFnPointer) => {
296 // FIXME(#19925) once fn item types are
297 // zero-sized, we'll need to do something here
299 Some(AdjustUnsafeFnPointer) => {
300 // purely a type-level thing
302 Some(AdjustDerefRef(adj)) => {
304 // Save the last autoderef in case we can avoid it.
305 if adj.autoderefs > 0 {
306 for _ in 0..adj.autoderefs-1 {
307 let (dv, dt) = const_deref(cx, llconst, ty);
313 if adj.autoref.is_some() {
314 if adj.autoderefs == 0 {
315 // Don't copy data to do a deref+ref
316 // (i.e., skip the last auto-deref).
317 llconst = addr_of(cx, llconst, "autoref");
318 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
321 let (dv, dt) = const_deref(cx, llconst, ty);
324 // If we derefed a fat pointer then we will have an
325 // open type here. So we need to update the type with
326 // the one returned from const_deref.
330 if let Some(target) = adj.unsize {
331 let target = monomorphize::apply_param_substs(cx.tcx(),
335 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
336 .expect("consts: unsizing got non-pointer type").ty;
337 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
338 // Normally, the source is a thin pointer and we are
339 // adding extra info to make a fat pointer. The exception
340 // is when we are upcasting an existing object fat pointer
341 // to use a different vtable. In that case, we want to
342 // load out the original data pointer so we can repackage
344 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
345 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
350 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
351 .expect("consts: unsizing got non-pointer target type").ty;
352 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
353 let base = ptrcast(base, ptr_ty);
354 let info = expr::unsized_info(cx, pointee_ty, unsized_ty,
355 old_info, param_substs);
357 if old_info.is_none() {
358 let prev_const = cx.const_unsized().borrow_mut()
359 .insert(base, llconst);
360 assert!(prev_const.is_none() || prev_const == Some(llconst));
362 assert_eq!(abi::FAT_PTR_ADDR, 0);
363 assert_eq!(abi::FAT_PTR_EXTRA, 1);
364 llconst = C_struct(cx, &[base, info], false);
370 let llty = type_of::sizing_type_of(cx, ety_adjusted);
371 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
372 let tsize = machine::llsize_of_alloc(cx, llty);
374 cx.sess().abort_if_errors();
376 // FIXME these values could use some context
377 llvm::LLVMDumpValue(llconst);
378 llvm::LLVMDumpValue(C_undef(llty));
380 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
384 (llconst, ety_adjusted)
387 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
389 // The only kind of unary expression that we check for validity
390 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
391 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
393 // An unfortunate special case: we parse e.g. -128 as a
394 // negation of the literal 128, which means if we're expecting
395 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
396 // 128 will have already overflowed to -128, and so then the
397 // constant evaluator thinks we're trying to negate -128.
399 // Catch this up front by looking for ExprLit directly,
400 // and just accepting it.
401 if let hir::ExprLit(_) = inner_e.node { return; }
403 let result = match t.sty {
404 ty::TyInt(int_type) => {
405 let input = match const_to_opt_int(te) {
409 const_int_checked_neg(
410 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
412 ty::TyUint(uint_type) => {
413 let input = match const_to_opt_uint(te) {
417 const_uint_checked_neg(
418 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
423 // We do not actually care about a successful result.
424 if let Err(err) = result {
425 cx.tcx().sess.span_err(e.span, &err.description());
430 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
431 te1: ValueRef, te2: ValueRef) {
432 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { return };
434 let result = match t.sty {
435 ty::TyInt(int_type) => {
436 let (lhs, rhs) = match (const_to_opt_int(te1),
437 const_to_opt_int(te2)) {
438 (Some(v1), Some(v2)) => (v1, v2),
442 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
444 hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
445 hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
446 hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
447 hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
448 hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
449 hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
450 hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
454 ty::TyUint(uint_type) => {
455 let (lhs, rhs) = match (const_to_opt_uint(te1),
456 const_to_opt_uint(te2)) {
457 (Some(v1), Some(v2)) => (v1, v2),
461 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
463 hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
464 hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
465 hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
466 hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
467 hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
468 hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
469 hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
475 // We do not actually care about a successful result.
476 if let Err(err) = result {
477 cx.tcx().sess.span_err(e.span, &err.description());
481 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
484 param_substs: &'tcx Substs<'tcx>,
488 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
493 let map_list = |exprs: &[P<hir::Expr>]| -> Vec<ValueRef> {
495 .map(|e| const_expr(cx, &**e, param_substs, fn_args).0)
498 let _icx = push_ctxt("const_expr");
500 hir::ExprLit(ref lit) => {
501 const_lit(cx, e, &**lit)
503 hir::ExprBinary(b, ref e1, ref e2) => {
504 /* Neither type is bottom, and we expect them to be unified
505 * already, so the following is safe. */
506 let (te1, ty) = const_expr(cx, &**e1, param_substs, fn_args);
507 debug!("const_expr_unadjusted: te1={}, ty={:?}",
508 cx.tn().val_to_string(te1),
510 assert!(!ty.is_simd());
511 let is_float = ty.is_fp();
512 let signed = ty.is_signed();
514 let (te2, _) = const_expr(cx, &**e2, param_substs, fn_args);
516 check_binary_expr_validity(cx, e, ty, te1, te2);
518 unsafe { match b.node {
519 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
520 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
522 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
523 hir::BiSub => llvm::LLVMConstSub(te1, te2),
525 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
526 hir::BiMul => llvm::LLVMConstMul(te1, te2),
528 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
529 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
530 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
532 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
533 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
534 hir::BiRem => llvm::LLVMConstURem(te1, te2),
536 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
537 hir::BiOr => llvm::LLVMConstOr(te1, te2),
538 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
539 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
540 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
542 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
543 llvm::LLVMConstShl(te1, te2)
546 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
547 if signed { llvm::LLVMConstAShr(te1, te2) }
548 else { llvm::LLVMConstLShr(te1, te2) }
550 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
552 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
553 ConstFCmp(cmp, te1, te2)
555 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
556 ConstICmp(cmp, te1, te2)
559 } } // unsafe { match b.node {
561 hir::ExprUnary(u, ref inner_e) => {
562 let (te, ty) = const_expr(cx, &**inner_e, param_substs, fn_args);
564 check_unary_expr_validity(cx, e, ty, te);
566 let is_float = ty.is_fp();
568 hir::UnDeref => const_deref(cx, te, ty).0,
569 hir::UnNot => llvm::LLVMConstNot(te),
570 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
571 hir::UnNeg => llvm::LLVMConstNeg(te),
574 hir::ExprField(ref base, field) => {
575 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
576 let brepr = adt::represent_type(cx, bt);
577 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
578 let ix = vinfo.field_index(field.node);
579 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, ix)
581 hir::ExprTupField(ref base, idx) => {
582 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
583 let brepr = adt::represent_type(cx, bt);
584 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
585 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, idx.node)
588 hir::ExprIndex(ref base, ref index) => {
589 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
590 let iv = match eval_const_expr_partial(cx.tcx(), &index, ExprTypeChecked) {
591 Ok(ConstVal::Int(i)) => i as u64,
592 Ok(ConstVal::Uint(u)) => u,
593 _ => cx.sess().span_bug(index.span,
594 "index is not an integer-constant expression")
596 let (arr, len) = match bt.sty {
597 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
598 ty::TySlice(_) | ty::TyStr => {
599 let e1 = const_get_elt(cx, bv, &[0]);
600 (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1]))
602 ty::TyRef(_, mt) => match mt.ty.sty {
603 ty::TyArray(_, u) => {
604 (const_deref_ptr(cx, bv), C_uint(cx, u))
606 _ => cx.sess().span_bug(base.span,
607 &format!("index-expr base must be a vector \
608 or string type, found {:?}",
611 _ => cx.sess().span_bug(base.span,
612 &format!("index-expr base must be a vector \
613 or string type, found {:?}",
617 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
618 let len = match bt.sty {
619 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
629 // FIXME #3170: report this earlier on in the const-eval
630 // pass. Reporting here is a bit late.
631 cx.sess().span_err(e.span,
632 "const index-expr is out of bounds");
633 C_undef(type_of::type_of(cx, bt).element_type())
635 const_get_elt(cx, arr, &[iv as c_uint])
638 hir::ExprCast(ref base, _) => {
640 let llty = type_of::type_of(cx, t_cast);
641 let (v, t_expr) = const_expr(cx, &**base, param_substs, fn_args);
642 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
643 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
646 if type_is_fat_ptr(cx.tcx(), t_expr) {
647 // Fat pointer casts.
649 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
650 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
651 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
653 if type_is_fat_ptr(cx.tcx(), t_cast) {
654 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
655 return C_struct(cx, &[addr, info], false)
661 CastTy::from_ty(t_expr).expect("bad input type for cast"),
662 CastTy::from_ty(t_cast).expect("bad output type for cast"),
664 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
665 let repr = adt::represent_type(cx, t_expr);
666 let discr = adt::const_get_discrim(cx, &*repr, v);
667 let iv = C_integral(cx.int_type(), discr, false);
668 let s = adt::is_discr_signed(&*repr) as Bool;
669 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
671 (CastTy::Int(_), CastTy::Int(_)) => {
672 let s = t_expr.is_signed() as Bool;
673 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
675 (CastTy::Int(_), CastTy::Float) => {
676 if t_expr.is_signed() {
677 llvm::LLVMConstSIToFP(v, llty.to_ref())
679 llvm::LLVMConstUIToFP(v, llty.to_ref())
682 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
683 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
684 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
685 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
686 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
689 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
690 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
691 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
692 llvm::LLVMConstPtrToInt(v, llty.to_ref())
695 cx.sess().impossible_case(e.span,
696 "bad combination of types for cast")
698 } } // unsafe { match ( ... ) {
700 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
701 // If this is the address of some static, then we need to return
702 // the actual address of the static itself (short circuit the rest
707 hir::ExprBlock(ref blk) => {
708 if let Some(ref sub) = blk.expr {
717 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
718 if let Some(def::DefStatic(def_id, _)) = opt_def {
719 get_static_val(cx, def_id, ety)
721 // If this isn't the address of a static, then keep going through
722 // normal constant evaluation.
723 let (v, _) = const_expr(cx, &**sub, param_substs, fn_args);
724 addr_of(cx, v, "ref")
727 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
728 let (v, _) = const_expr(cx, &**sub, param_substs, fn_args);
729 addr_of_mut(cx, v, "ref_mut_slice")
731 hir::ExprTup(ref es) => {
732 let repr = adt::represent_type(cx, ety);
733 let vals = map_list(&es[..]);
734 adt::trans_const(cx, &*repr, 0, &vals[..])
736 hir::ExprStruct(_, ref fs, ref base_opt) => {
737 let repr = adt::represent_type(cx, ety);
739 let base_val = match *base_opt {
740 Some(ref base) => Some(const_expr(cx, &**base, param_substs, fn_args)),
744 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
745 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
746 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
747 (Some(ref f), _) => const_expr(cx, &*f.expr, param_substs, fn_args).0,
748 (_, Some((bv, _))) => adt::const_get_field(cx, &*repr, bv, discr, ix),
749 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
751 }).collect::<Vec<_>>();
755 adt::trans_const(cx, &*repr, discr, &cs[..])
758 hir::ExprVec(ref es) => {
759 let unit_ty = ety.sequence_element_type(cx.tcx());
760 let llunitty = type_of::type_of(cx, unit_ty);
762 .map(|e| const_expr(cx, &**e, param_substs, fn_args).0)
763 .collect::<Vec<_>>();
764 // If the vector contains enums, an LLVM array won't work.
765 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
766 C_struct(cx, &vs[..], false)
768 C_array(llunitty, &vs[..])
771 hir::ExprRepeat(ref elem, ref count) => {
772 let unit_ty = ety.sequence_element_type(cx.tcx());
773 let llunitty = type_of::type_of(cx, unit_ty);
774 let n = cx.tcx().eval_repeat_count(count);
775 let unit_val = const_expr(cx, &**elem, param_substs, fn_args).0;
776 let vs = vec![unit_val; n];
777 if val_ty(unit_val) != llunitty {
778 C_struct(cx, &vs[..], false)
780 C_array(llunitty, &vs[..])
783 hir::ExprPath(..) => {
784 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
786 def::DefLocal(_, id) => {
787 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
790 cx.sess().span_bug(e.span, "const fn argument not found")
793 def::DefFn(..) | def::DefMethod(..) => {
794 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
796 def::DefConst(def_id) | def::DefAssociatedConst(def_id) => {
797 const_deref_ptr(cx, get_const_val(cx, def_id, e))
799 def::DefVariant(enum_did, variant_did, _) => {
800 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
802 ty::VariantKind::Unit => {
803 let repr = adt::represent_type(cx, ety);
804 adt::trans_const(cx, &*repr, vinfo.disr_val, &[])
806 ty::VariantKind::Tuple => {
807 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
809 ty::VariantKind::Dict => {
810 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
814 def::DefStruct(_) => {
815 if let ty::TyBareFn(..) = ety.sty {
817 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
820 C_null(type_of::type_of(cx, ety))
824 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
829 hir::ExprCall(ref callee, ref args) => {
830 let mut callee = &**callee;
832 callee = match callee.node {
833 hir::ExprBlock(ref block) => match block.expr {
834 Some(ref tail) => &**tail,
840 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
841 let arg_vals = map_list(args);
843 def::DefFn(did, _) | def::DefMethod(did) => {
844 const_fn_call(cx, ExprId(callee.id), did, &arg_vals, param_substs)
846 def::DefStruct(_) => {
848 C_vector(&arg_vals[..])
850 let repr = adt::represent_type(cx, ety);
851 adt::trans_const(cx, &*repr, 0, &arg_vals[..])
854 def::DefVariant(enum_did, variant_did, _) => {
855 let repr = adt::represent_type(cx, ety);
856 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
862 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
865 hir::ExprMethodCall(_, _, ref args) => {
866 let arg_vals = map_list(args);
867 let method_call = ty::MethodCall::expr(e.id);
868 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
869 const_fn_call(cx, MethodCallKey(method_call),
870 method_did, &arg_vals, param_substs)
872 hir::ExprBlock(ref block) => {
874 Some(ref expr) => const_expr(cx, &**expr, param_substs, fn_args).0,
878 hir::ExprClosure(_, ref decl, ref body) => {
880 ty::TyClosure(_, ref substs) => {
881 closure::trans_closure_expr(closure::Dest::Ignore(cx), decl,
887 &format!("bad type for closure expr: {:?}", ety))
889 C_null(type_of::type_of(cx, ety))
891 _ => cx.sess().span_bug(e.span,
892 "bad constant expression type in consts::const_expr"),
895 pub fn trans_static(ccx: &CrateContext,
899 attrs: &Vec<ast::Attribute>)
902 let _icx = push_ctxt("trans_static");
903 let g = base::get_item_val(ccx, id);
905 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
906 let (v, _) = const_expr(ccx, expr, empty_substs, None);
908 // boolean SSA values are i1, but they have to be stored in i8 slots,
909 // otherwise some LLVM optimization passes don't work as expected
910 let mut val_llty = llvm::LLVMTypeOf(v);
911 let v = if val_llty == Type::i1(ccx).to_ref() {
912 val_llty = Type::i8(ccx).to_ref();
913 llvm::LLVMConstZExt(v, val_llty)
918 let ty = ccx.tcx().node_id_to_type(id);
919 let llty = type_of::type_of(ccx, ty);
920 let g = if val_llty == llty.to_ref() {
923 // If we created the global with the wrong type,
925 let empty_string = CString::new("").unwrap();
926 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
927 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
928 llvm::LLVMSetValueName(g, empty_string.as_ptr());
929 let new_g = llvm::LLVMGetOrInsertGlobal(
930 ccx.llmod(), name_string.as_ptr(), val_llty);
931 // To avoid breaking any invariants, we leave around the old
932 // global for the moment; we'll replace all references to it
933 // with the new global later. (See base::trans_crate.)
934 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
937 llvm::LLVMSetInitializer(g, v);
939 // As an optimization, all shared statics which do not have interior
940 // mutability are placed into read-only memory.
941 if m != hir::MutMutable {
942 let tcontents = ty.type_contents(ccx.tcx());
943 if !tcontents.interior_unsafe() {
944 llvm::LLVMSetGlobalConstant(g, llvm::True);
948 debuginfo::create_global_var_metadata(ccx, id, g);
950 if attr::contains_name(attrs,
952 llvm::set_thread_local(g, true);
959 fn get_static_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
963 if let Some(node_id) = ccx.tcx().map.as_local_node_id(did) {
964 base::get_item_val(ccx, node_id)
966 base::trans_external_path(ccx, did, ty)