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::{check_const, def};
17 use middle::const_eval::{self, ConstVal};
18 use middle::const_eval::{const_int_checked_neg, const_uint_checked_neg};
19 use middle::const_eval::{const_int_checked_add, const_uint_checked_add};
20 use middle::const_eval::{const_int_checked_sub, const_uint_checked_sub};
21 use middle::const_eval::{const_int_checked_mul, const_uint_checked_mul};
22 use middle::const_eval::{const_int_checked_div, const_uint_checked_div};
23 use middle::const_eval::{const_int_checked_rem, const_uint_checked_rem};
24 use middle::const_eval::{const_int_checked_shl, const_uint_checked_shl};
25 use middle::const_eval::{const_int_checked_shr, const_uint_checked_shr};
26 use middle::const_eval::EvalHint::ExprTypeChecked;
27 use middle::const_eval::eval_const_expr_partial;
28 use trans::{adt, closure, debuginfo, expr, inline, machine};
29 use trans::base::{self, push_ctxt};
32 use trans::monomorphize;
33 use trans::type_::Type;
35 use middle::cast::{CastTy,IntTy};
36 use middle::subst::Substs;
37 use middle::ty::{self, Ty};
38 use util::nodemap::NodeMap;
40 use std::ffi::{CStr, CString};
42 use syntax::{ast, ast_util, attr};
43 use syntax::parse::token;
46 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
48 pub fn const_lit(cx: &CrateContext, e: &ast::Expr, lit: &ast::Lit)
50 let _icx = push_ctxt("trans_lit");
51 debug!("const_lit: {:?}", lit);
53 ast::LitByte(b) => C_integral(Type::uint_from_ty(cx, ast::TyU8), b as u64, false),
54 ast::LitChar(i) => C_integral(Type::char(cx), i as u64, false),
55 ast::LitInt(i, ast::SignedIntLit(t, _)) => {
56 C_integral(Type::int_from_ty(cx, t), i, true)
58 ast::LitInt(u, ast::UnsignedIntLit(t)) => {
59 C_integral(Type::uint_from_ty(cx, t), u, false)
61 ast::LitInt(i, ast::UnsuffixedIntLit(_)) => {
62 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
63 match lit_int_ty.sty {
65 C_integral(Type::int_from_ty(cx, t), i as u64, true)
68 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
70 _ => cx.sess().span_bug(lit.span,
71 &format!("integer literal has type {:?} (expected int \
76 ast::LitFloat(ref fs, t) => {
77 C_floating(&fs, Type::float_from_ty(cx, t))
79 ast::LitFloatUnsuffixed(ref fs) => {
80 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
81 match lit_float_ty.sty {
83 C_floating(&fs, Type::float_from_ty(cx, t))
86 cx.sess().span_bug(lit.span,
87 "floating point literal doesn't have the right type");
91 ast::LitBool(b) => C_bool(cx, b),
92 ast::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()),
93 ast::LitBinary(ref data) => {
94 addr_of(cx, C_bytes(cx, &data[..]), "binary")
99 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
101 llvm::LLVMConstPointerCast(val, ty.to_ref())
105 fn addr_of_mut(ccx: &CrateContext,
110 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
111 // counter? Also most other uses of gensym in trans.
112 let gsym = token::gensym("_");
113 let name = format!("{}{}", kind, gsym.usize());
114 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
115 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
117 llvm::LLVMSetInitializer(gv, cv);
118 SetLinkage(gv, InternalLinkage);
119 SetUnnamedAddr(gv, true);
124 pub fn addr_of(ccx: &CrateContext,
128 match ccx.const_globals().borrow().get(&cv) {
129 Some(&gv) => return gv,
132 let gv = addr_of_mut(ccx, cv, kind);
134 llvm::LLVMSetGlobalConstant(gv, True);
136 ccx.const_globals().borrow_mut().insert(cv, gv);
140 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
141 let v = match cx.const_unsized().borrow().get(&v) {
146 llvm::LLVMGetInitializer(v)
150 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
153 -> (ValueRef, Ty<'tcx>) {
154 match ty.builtin_deref(true) {
156 if type_is_sized(cx.tcx(), mt.ty) {
157 (const_deref_ptr(cx, v), mt.ty)
159 // Derefing a fat pointer does not change the representation,
160 // just the type to the unsized contents.
165 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
171 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
172 node: ExprOrMethodCall,
174 arg_vals: &[ValueRef],
175 param_substs: &'tcx Substs<'tcx>) -> ValueRef {
176 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
177 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
179 let args = &fn_like.decl().inputs;
180 assert_eq!(args.len(), arg_vals.len());
182 let arg_ids = args.iter().map(|arg| arg.pat.id);
183 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
185 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
186 match fn_like.body().expr {
188 const_expr(ccx, &**expr, substs, Some(&fn_args)).0
194 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
196 ref_expr: &ast::Expr)
198 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
200 if def_id.krate != ast::LOCAL_CRATE {
201 ccx.sess().span_bug(ref_expr.span,
202 "cross crate constant could not be inlined");
205 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id)) {
206 Some(ref expr) => expr,
208 ccx.sess().span_bug(ref_expr.span, "constant item not found")
213 fn get_const_val(ccx: &CrateContext,
215 ref_expr: &ast::Expr) -> ValueRef {
216 let expr = get_const_expr(ccx, def_id, ref_expr);
217 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
218 get_const_expr_as_global(ccx, expr, check_const::ConstQualif::empty(), empty_substs)
221 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
223 qualif: check_const::ConstQualif,
224 param_substs: &'tcx Substs<'tcx>)
226 debug!("get_const_expr_as_global: {:?}", expr.id);
227 // Special-case constants to cache a common global for all uses.
229 ast::ExprPath(..) => {
230 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
232 def::DefConst(def_id) | def::DefAssociatedConst(def_id) => {
233 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
234 debug!("get_const_expr_as_global ({:?}): found const {:?}",
236 return get_const_val(ccx, def_id, expr);
245 let key = (expr.id, param_substs);
246 match ccx.const_values().borrow().get(&key) {
247 Some(&val) => return val,
250 let val = if qualif.intersects(check_const::ConstQualif::NON_STATIC_BORROWS) {
251 // Avoid autorefs as they would create global instead of stack
252 // references, even when only the latter are correct.
253 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
254 &ccx.tcx().expr_ty(expr));
255 const_expr_unadjusted(ccx, expr, ty, param_substs, None)
257 const_expr(ccx, expr, param_substs, None).0
260 // boolean SSA values are i1, but they have to be stored in i8 slots,
261 // otherwise some LLVM optimization passes don't work as expected
263 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
264 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
270 let lvalue = addr_of(ccx, val, "const");
271 ccx.const_values().borrow_mut().insert(key, lvalue);
275 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
277 param_substs: &'tcx Substs<'tcx>,
279 -> (ValueRef, Ty<'tcx>) {
280 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
281 &cx.tcx().expr_ty(e));
282 let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args);
283 let mut llconst = llconst;
284 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
285 &cx.tcx().expr_ty_adjusted(e));
286 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
288 Some(ty::AdjustReifyFnPointer) => {
289 // FIXME(#19925) once fn item types are
290 // zero-sized, we'll need to do something here
292 Some(ty::AdjustUnsafeFnPointer) => {
293 // purely a type-level thing
295 Some(ty::AdjustDerefRef(adj)) => {
297 // Save the last autoderef in case we can avoid it.
298 if adj.autoderefs > 0 {
299 for _ in 0..adj.autoderefs-1 {
300 let (dv, dt) = const_deref(cx, llconst, ty);
306 if adj.autoref.is_some() {
307 if adj.autoderefs == 0 {
308 // Don't copy data to do a deref+ref
309 // (i.e., skip the last auto-deref).
310 llconst = addr_of(cx, llconst, "autoref");
311 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
314 let (dv, dt) = const_deref(cx, llconst, ty);
317 // If we derefed a fat pointer then we will have an
318 // open type here. So we need to update the type with
319 // the one returned from const_deref.
323 if let Some(target) = adj.unsize {
324 let target = monomorphize::apply_param_substs(cx.tcx(),
328 let pointee_ty = ty.builtin_deref(true)
329 .expect("consts: unsizing got non-pointer type").ty;
330 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
331 // Normally, the source is a thin pointer and we are
332 // adding extra info to make a fat pointer. The exception
333 // is when we are upcasting an existing object fat pointer
334 // to use a different vtable. In that case, we want to
335 // load out the original data pointer so we can repackage
337 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
338 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
343 let unsized_ty = target.builtin_deref(true)
344 .expect("consts: unsizing got non-pointer target type").ty;
345 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
346 let base = ptrcast(base, ptr_ty);
347 let info = expr::unsized_info(cx, pointee_ty, unsized_ty,
348 old_info, param_substs);
350 if old_info.is_none() {
351 let prev_const = cx.const_unsized().borrow_mut()
352 .insert(base, llconst);
353 assert!(prev_const.is_none() || prev_const == Some(llconst));
355 assert_eq!(abi::FAT_PTR_ADDR, 0);
356 assert_eq!(abi::FAT_PTR_EXTRA, 1);
357 llconst = C_struct(cx, &[base, info], false);
363 let llty = type_of::sizing_type_of(cx, ety_adjusted);
364 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
365 let tsize = machine::llsize_of_alloc(cx, llty);
367 cx.sess().abort_if_errors();
369 // FIXME these values could use some context
370 llvm::LLVMDumpValue(llconst);
371 llvm::LLVMDumpValue(C_undef(llty));
373 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
377 (llconst, ety_adjusted)
380 fn check_unary_expr_validity(cx: &CrateContext, e: &ast::Expr, t: Ty,
382 // The only kind of unary expression that we check for validity
383 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
384 if let ast::ExprUnary(ast::UnNeg, ref inner_e) = e.node {
386 // An unfortunate special case: we parse e.g. -128 as a
387 // negation of the literal 128, which means if we're expecting
388 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
389 // 128 will have already overflowed to -128, and so then the
390 // constant evaluator thinks we're trying to negate -128.
392 // Catch this up front by looking for ExprLit directly,
393 // and just accepting it.
394 if let ast::ExprLit(_) = inner_e.node { return; }
396 let result = match t.sty {
397 ty::TyInt(int_type) => {
398 let input = match const_to_opt_int(te) {
402 const_int_checked_neg(
403 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
405 ty::TyUint(uint_type) => {
406 let input = match const_to_opt_uint(te) {
410 const_uint_checked_neg(
411 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
416 // We do not actually care about a successful result.
417 if let Err(err) = result {
418 cx.tcx().sess.span_err(e.span, &err.description());
423 fn check_binary_expr_validity(cx: &CrateContext, e: &ast::Expr, t: Ty,
424 te1: ValueRef, te2: ValueRef) {
425 let b = if let ast::ExprBinary(b, _, _) = e.node { b } else { return };
427 let result = match t.sty {
428 ty::TyInt(int_type) => {
429 let (lhs, rhs) = match (const_to_opt_int(te1),
430 const_to_opt_int(te2)) {
431 (Some(v1), Some(v2)) => (v1, v2),
435 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
437 ast::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
438 ast::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
439 ast::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
440 ast::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
441 ast::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
442 ast::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
443 ast::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
447 ty::TyUint(uint_type) => {
448 let (lhs, rhs) = match (const_to_opt_uint(te1),
449 const_to_opt_uint(te2)) {
450 (Some(v1), Some(v2)) => (v1, v2),
454 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
456 ast::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
457 ast::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
458 ast::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
459 ast::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
460 ast::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
461 ast::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
462 ast::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
468 // We do not actually care about a successful result.
469 if let Err(err) = result {
470 cx.tcx().sess.span_err(e.span, &err.description());
474 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
477 param_substs: &'tcx Substs<'tcx>,
481 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
486 let map_list = |exprs: &[P<ast::Expr>]| -> Vec<ValueRef> {
488 .map(|e| const_expr(cx, &**e, param_substs, fn_args).0)
491 let _icx = push_ctxt("const_expr");
493 ast::ExprLit(ref lit) => {
494 const_lit(cx, e, &**lit)
496 ast::ExprBinary(b, ref e1, ref e2) => {
497 /* Neither type is bottom, and we expect them to be unified
498 * already, so the following is safe. */
499 let (te1, ty) = const_expr(cx, &**e1, param_substs, fn_args);
500 debug!("const_expr_unadjusted: te1={}, ty={:?}",
501 cx.tn().val_to_string(te1),
503 let is_simd = ty.is_simd();
504 let intype = if is_simd {
505 ty.simd_type(cx.tcx())
509 let is_float = intype.is_fp();
510 let signed = intype.is_signed();
512 let (te2, _) = const_expr(cx, &**e2, param_substs, fn_args);
514 check_binary_expr_validity(cx, e, ty, te1, te2);
516 unsafe { match b.node {
517 ast::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
518 ast::BiAdd => llvm::LLVMConstAdd(te1, te2),
520 ast::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
521 ast::BiSub => llvm::LLVMConstSub(te1, te2),
523 ast::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
524 ast::BiMul => llvm::LLVMConstMul(te1, te2),
526 ast::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
527 ast::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
528 ast::BiDiv => llvm::LLVMConstUDiv(te1, te2),
530 ast::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
531 ast::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
532 ast::BiRem => llvm::LLVMConstURem(te1, te2),
534 ast::BiAnd => llvm::LLVMConstAnd(te1, te2),
535 ast::BiOr => llvm::LLVMConstOr(te1, te2),
536 ast::BiBitXor => llvm::LLVMConstXor(te1, te2),
537 ast::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
538 ast::BiBitOr => llvm::LLVMConstOr(te1, te2),
540 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
541 llvm::LLVMConstShl(te1, te2)
544 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
545 if signed { llvm::LLVMConstAShr(te1, te2) }
546 else { llvm::LLVMConstLShr(te1, te2) }
548 ast::BiEq | ast::BiNe | ast::BiLt | ast::BiLe | ast::BiGt | ast::BiGe => {
550 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
551 ConstFCmp(cmp, te1, te2)
553 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
554 let bool_val = ConstICmp(cmp, te1, te2);
556 // LLVM outputs an `< size x i1 >`, so we need to perform
557 // a sign extension to get the correctly sized type.
558 llvm::LLVMConstIntCast(bool_val, val_ty(te1).to_ref(), True)
564 } } // unsafe { match b.node {
566 ast::ExprUnary(u, ref inner_e) => {
567 let (te, ty) = const_expr(cx, &**inner_e, param_substs, fn_args);
569 check_unary_expr_validity(cx, e, ty, te);
571 let is_float = ty.is_fp();
573 ast::UnUniq | ast::UnDeref => const_deref(cx, te, ty).0,
574 ast::UnNot => llvm::LLVMConstNot(te),
575 ast::UnNeg if is_float => llvm::LLVMConstFNeg(te),
576 ast::UnNeg => llvm::LLVMConstNeg(te),
579 ast::ExprField(ref base, field) => {
580 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
581 let brepr = adt::represent_type(cx, bt);
582 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
583 let ix = vinfo.field_index(field.node.name);
584 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, ix)
586 ast::ExprTupField(ref base, idx) => {
587 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
588 let brepr = adt::represent_type(cx, bt);
589 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
590 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, idx.node)
593 ast::ExprIndex(ref base, ref index) => {
594 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
595 let iv = match eval_const_expr_partial(cx.tcx(), &index, ExprTypeChecked) {
596 Ok(ConstVal::Int(i)) => i as u64,
597 Ok(ConstVal::Uint(u)) => u,
598 _ => cx.sess().span_bug(index.span,
599 "index is not an integer-constant expression")
601 let (arr, len) = match bt.sty {
602 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
603 ty::TySlice(_) | ty::TyStr => {
604 let e1 = const_get_elt(cx, bv, &[0]);
605 (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1]))
607 ty::TyRef(_, mt) => match mt.ty.sty {
608 ty::TyArray(_, u) => {
609 (const_deref_ptr(cx, bv), C_uint(cx, u))
611 _ => cx.sess().span_bug(base.span,
612 &format!("index-expr base must be a vector \
613 or string type, found {:?}",
616 _ => cx.sess().span_bug(base.span,
617 &format!("index-expr base must be a vector \
618 or string type, found {:?}",
622 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
623 let len = match bt.sty {
624 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
634 // FIXME #3170: report this earlier on in the const-eval
635 // pass. Reporting here is a bit late.
636 cx.sess().span_err(e.span,
637 "const index-expr is out of bounds");
638 C_undef(type_of::type_of(cx, bt).element_type())
640 const_get_elt(cx, arr, &[iv as c_uint])
643 ast::ExprCast(ref base, _) => {
645 let llty = type_of::type_of(cx, t_cast);
646 let (v, t_expr) = const_expr(cx, &**base, param_substs, fn_args);
647 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
648 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
651 if type_is_fat_ptr(cx.tcx(), t_expr) {
652 // Fat pointer casts.
653 let t_cast_inner = t_cast.builtin_deref(true).expect("cast to non-pointer").ty;
654 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
655 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
657 if type_is_fat_ptr(cx.tcx(), t_cast) {
658 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
659 return C_struct(cx, &[addr, info], false)
665 CastTy::from_ty(t_expr).expect("bad input type for cast"),
666 CastTy::from_ty(t_cast).expect("bad output type for cast"),
668 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
669 let repr = adt::represent_type(cx, t_expr);
670 let discr = adt::const_get_discrim(cx, &*repr, v);
671 let iv = C_integral(cx.int_type(), discr, false);
672 let s = adt::is_discr_signed(&*repr) as Bool;
673 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
675 (CastTy::Int(_), CastTy::Int(_)) => {
676 let s = t_expr.is_signed() as Bool;
677 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
679 (CastTy::Int(_), CastTy::Float) => {
680 if t_expr.is_signed() {
681 llvm::LLVMConstSIToFP(v, llty.to_ref())
683 llvm::LLVMConstUIToFP(v, llty.to_ref())
686 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
687 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
688 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
689 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
690 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
693 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
694 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
695 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
696 llvm::LLVMConstPtrToInt(v, llty.to_ref())
699 cx.sess().impossible_case(e.span,
700 "bad combination of types for cast")
702 } } // unsafe { match ( ... ) {
704 ast::ExprAddrOf(ast::MutImmutable, ref sub) => {
705 // If this is the address of some static, then we need to return
706 // the actual address of the static itself (short circuit the rest
711 ast::ExprParen(ref sub) => cur = sub,
712 ast::ExprBlock(ref blk) => {
713 if let Some(ref sub) = blk.expr {
722 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
723 if let Some(def::DefStatic(def_id, _)) = opt_def {
724 get_static_val(cx, def_id, ety)
726 // If this isn't the address of a static, then keep going through
727 // normal constant evaluation.
728 let (v, _) = const_expr(cx, &**sub, param_substs, fn_args);
729 addr_of(cx, v, "ref")
732 ast::ExprAddrOf(ast::MutMutable, ref sub) => {
733 let (v, _) = const_expr(cx, &**sub, param_substs, fn_args);
734 addr_of_mut(cx, v, "ref_mut_slice")
736 ast::ExprTup(ref es) => {
737 let repr = adt::represent_type(cx, ety);
738 let vals = map_list(&es[..]);
739 adt::trans_const(cx, &*repr, 0, &vals[..])
741 ast::ExprStruct(_, ref fs, ref base_opt) => {
742 let repr = adt::represent_type(cx, ety);
744 let base_val = match *base_opt {
745 Some(ref base) => Some(const_expr(cx, &**base, param_substs, fn_args)),
749 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
750 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
751 match (fs.iter().find(|f| f_name == f.ident.node.name), base_val) {
752 (Some(ref f), _) => const_expr(cx, &*f.expr, param_substs, fn_args).0,
753 (_, Some((bv, _))) => adt::const_get_field(cx, &*repr, bv, discr, ix),
754 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
756 }).collect::<Vec<_>>();
760 adt::trans_const(cx, &*repr, discr, &cs[..])
763 ast::ExprVec(ref es) => {
764 let unit_ty = ety.sequence_element_type(cx.tcx());
765 let llunitty = type_of::type_of(cx, unit_ty);
767 .map(|e| const_expr(cx, &**e, param_substs, fn_args).0)
768 .collect::<Vec<_>>();
769 // If the vector contains enums, an LLVM array won't work.
770 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
771 C_struct(cx, &vs[..], false)
773 C_array(llunitty, &vs[..])
776 ast::ExprRepeat(ref elem, ref count) => {
777 let unit_ty = ety.sequence_element_type(cx.tcx());
778 let llunitty = type_of::type_of(cx, unit_ty);
779 let n = cx.tcx().eval_repeat_count(count);
780 let unit_val = const_expr(cx, &**elem, param_substs, fn_args).0;
781 let vs = vec![unit_val; n];
782 if val_ty(unit_val) != llunitty {
783 C_struct(cx, &vs[..], false)
785 C_array(llunitty, &vs[..])
788 ast::ExprPath(..) => {
789 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
791 def::DefLocal(id) => {
792 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
795 cx.sess().span_bug(e.span, "const fn argument not found")
798 def::DefFn(..) | def::DefMethod(..) => {
799 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
801 def::DefConst(def_id) | def::DefAssociatedConst(def_id) => {
802 const_deref_ptr(cx, get_const_val(cx, def_id, e))
804 def::DefVariant(enum_did, variant_did, _) => {
805 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
807 ty::VariantKind::Unit => {
808 let repr = adt::represent_type(cx, ety);
809 adt::trans_const(cx, &*repr, vinfo.disr_val, &[])
811 ty::VariantKind::Tuple => {
812 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
814 ty::VariantKind::Dict => {
815 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
819 def::DefStruct(_) => {
820 if let ty::TyBareFn(..) = ety.sty {
822 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
825 C_null(type_of::type_of(cx, ety))
829 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
834 ast::ExprCall(ref callee, ref args) => {
835 let mut callee = &**callee;
837 callee = match callee.node {
838 ast::ExprParen(ref inner) => &**inner,
839 ast::ExprBlock(ref block) => match block.expr {
840 Some(ref tail) => &**tail,
846 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
847 let arg_vals = map_list(args);
849 def::DefFn(did, _) | def::DefMethod(did) => {
850 const_fn_call(cx, ExprId(callee.id), did, &arg_vals, param_substs)
852 def::DefStruct(_) => {
854 C_vector(&arg_vals[..])
856 let repr = adt::represent_type(cx, ety);
857 adt::trans_const(cx, &*repr, 0, &arg_vals[..])
860 def::DefVariant(enum_did, variant_did, _) => {
861 let repr = adt::represent_type(cx, ety);
862 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
868 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
871 ast::ExprMethodCall(_, _, ref args) => {
872 let arg_vals = map_list(args);
873 let method_call = ty::MethodCall::expr(e.id);
874 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
875 const_fn_call(cx, MethodCallKey(method_call),
876 method_did, &arg_vals, param_substs)
878 ast::ExprParen(ref e) => const_expr(cx, &**e, param_substs, fn_args).0,
879 ast::ExprBlock(ref block) => {
881 Some(ref expr) => const_expr(cx, &**expr, param_substs, fn_args).0,
885 ast::ExprClosure(_, ref decl, ref body) => {
887 ty::TyClosure(_, ref substs) => {
888 closure::trans_closure_expr(closure::Dest::Ignore(cx), decl,
894 &format!("bad type for closure expr: {:?}", ety))
896 C_null(type_of::type_of(cx, ety))
898 _ => cx.sess().span_bug(e.span,
899 "bad constant expression type in consts::const_expr"),
902 pub fn trans_static(ccx: &CrateContext,
906 attrs: &Vec<ast::Attribute>)
909 let _icx = push_ctxt("trans_static");
910 let g = base::get_item_val(ccx, id);
912 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
913 let (v, _) = const_expr(ccx, expr, empty_substs, None);
915 // boolean SSA values are i1, but they have to be stored in i8 slots,
916 // otherwise some LLVM optimization passes don't work as expected
917 let mut val_llty = llvm::LLVMTypeOf(v);
918 let v = if val_llty == Type::i1(ccx).to_ref() {
919 val_llty = Type::i8(ccx).to_ref();
920 llvm::LLVMConstZExt(v, val_llty)
925 let ty = ccx.tcx().node_id_to_type(id);
926 let llty = type_of::type_of(ccx, ty);
927 let g = if val_llty == llty.to_ref() {
930 // If we created the global with the wrong type,
932 let empty_string = CString::new("").unwrap();
933 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
934 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
935 llvm::LLVMSetValueName(g, empty_string.as_ptr());
936 let new_g = llvm::LLVMGetOrInsertGlobal(
937 ccx.llmod(), name_string.as_ptr(), val_llty);
938 // To avoid breaking any invariants, we leave around the old
939 // global for the moment; we'll replace all references to it
940 // with the new global later. (See base::trans_crate.)
941 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
944 llvm::LLVMSetInitializer(g, v);
946 // As an optimization, all shared statics which do not have interior
947 // mutability are placed into read-only memory.
948 if m != ast::MutMutable {
949 let tcontents = ty.type_contents(ccx.tcx());
950 if !tcontents.interior_unsafe() {
951 llvm::LLVMSetGlobalConstant(g, llvm::True);
955 debuginfo::create_global_var_metadata(ccx, id, g);
957 if attr::contains_name(attrs,
959 llvm::set_thread_local(g, true);
966 fn get_static_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, did: ast::DefId,
967 ty: Ty<'tcx>) -> ValueRef {
968 if ast_util::is_local(did) { return base::get_item_val(ccx, did.node) }
969 base::trans_external_path(ccx, did, ty)