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 trans::{adt, closure, debuginfo, expr, inline, machine};
27 use trans::base::{self, push_ctxt};
30 use trans::monomorphize;
31 use trans::type_::Type;
33 use middle::cast::{CastTy,IntTy};
34 use middle::subst::Substs;
35 use middle::ty::{self, Ty};
36 use util::nodemap::NodeMap;
38 use std::iter::repeat;
40 use syntax::{ast, ast_util};
41 use syntax::parse::token;
44 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
46 pub fn const_lit(cx: &CrateContext, e: &ast::Expr, lit: &ast::Lit)
48 let _icx = push_ctxt("trans_lit");
49 debug!("const_lit: {:?}", lit);
51 ast::LitByte(b) => C_integral(Type::uint_from_ty(cx, ast::TyU8), b as u64, false),
52 ast::LitChar(i) => C_integral(Type::char(cx), i as u64, false),
53 ast::LitInt(i, ast::SignedIntLit(t, _)) => {
54 C_integral(Type::int_from_ty(cx, t), i, true)
56 ast::LitInt(u, ast::UnsignedIntLit(t)) => {
57 C_integral(Type::uint_from_ty(cx, t), u, false)
59 ast::LitInt(i, ast::UnsuffixedIntLit(_)) => {
60 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
61 match lit_int_ty.sty {
63 C_integral(Type::int_from_ty(cx, t), i as u64, true)
66 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
68 _ => cx.sess().span_bug(lit.span,
69 &format!("integer literal has type {:?} (expected int \
74 ast::LitFloat(ref fs, t) => {
75 C_floating(&fs, Type::float_from_ty(cx, t))
77 ast::LitFloatUnsuffixed(ref fs) => {
78 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
79 match lit_float_ty.sty {
81 C_floating(&fs, Type::float_from_ty(cx, t))
84 cx.sess().span_bug(lit.span,
85 "floating point literal doesn't have the right type");
89 ast::LitBool(b) => C_bool(cx, b),
90 ast::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()),
91 ast::LitBinary(ref data) => {
92 addr_of(cx, C_bytes(cx, &data[..]), "binary")
97 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
99 llvm::LLVMConstPointerCast(val, ty.to_ref())
103 fn addr_of_mut(ccx: &CrateContext,
108 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
109 // counter? Also most other uses of gensym in trans.
110 let gsym = token::gensym("_");
111 let name = format!("{}{}", kind, gsym.usize());
112 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
113 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
115 llvm::LLVMSetInitializer(gv, cv);
116 SetLinkage(gv, InternalLinkage);
117 SetUnnamedAddr(gv, true);
122 pub fn addr_of(ccx: &CrateContext,
126 match ccx.const_globals().borrow().get(&cv) {
127 Some(&gv) => return gv,
130 let gv = addr_of_mut(ccx, cv, kind);
132 llvm::LLVMSetGlobalConstant(gv, True);
134 ccx.const_globals().borrow_mut().insert(cv, gv);
138 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
139 let v = match cx.const_unsized().borrow().get(&v) {
144 llvm::LLVMGetInitializer(v)
148 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
151 -> (ValueRef, Ty<'tcx>) {
152 match ty.builtin_deref(true) {
154 if type_is_sized(cx.tcx(), mt.ty) {
155 (const_deref_ptr(cx, v), mt.ty)
157 // Derefing a fat pointer does not change the representation,
158 // just the type to the unsized contents.
163 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
169 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
170 node: ExprOrMethodCall,
172 arg_vals: &[ValueRef],
173 param_substs: &'tcx Substs<'tcx>) -> ValueRef {
174 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
175 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
177 let args = &fn_like.decl().inputs;
178 assert_eq!(args.len(), arg_vals.len());
180 let arg_ids = args.iter().map(|arg| arg.pat.id);
181 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
183 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
184 match fn_like.body().expr {
186 const_expr(ccx, &**expr, substs, Some(&fn_args)).0
192 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
194 ref_expr: &ast::Expr)
196 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
198 if def_id.krate != ast::LOCAL_CRATE {
199 ccx.sess().span_bug(ref_expr.span,
200 "cross crate constant could not be inlined");
203 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id)) {
204 Some(ref expr) => expr,
206 ccx.sess().span_bug(ref_expr.span, "constant item not found")
211 fn get_const_val(ccx: &CrateContext,
213 ref_expr: &ast::Expr) -> ValueRef {
214 let expr = get_const_expr(ccx, def_id, ref_expr);
215 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
216 get_const_expr_as_global(ccx, expr, check_const::ConstQualif::empty(), empty_substs)
219 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
221 qualif: check_const::ConstQualif,
222 param_substs: &'tcx Substs<'tcx>)
224 debug!("get_const_expr_as_global: {:?}", expr.id);
225 // Special-case constants to cache a common global for all uses.
227 ast::ExprPath(..) => {
228 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
230 def::DefConst(def_id) | def::DefAssociatedConst(def_id, _) => {
231 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
232 debug!("get_const_expr_as_global ({:?}): found const {:?}",
234 return get_const_val(ccx, def_id, expr);
243 let key = (expr.id, param_substs);
244 match ccx.const_values().borrow().get(&key) {
245 Some(&val) => return val,
248 let val = if qualif.intersects(check_const::ConstQualif::NON_STATIC_BORROWS) {
249 // Avoid autorefs as they would create global instead of stack
250 // references, even when only the latter are correct.
251 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
252 &ccx.tcx().expr_ty(expr));
253 const_expr_unadjusted(ccx, expr, ty, param_substs, None)
255 const_expr(ccx, expr, param_substs, None).0
258 // boolean SSA values are i1, but they have to be stored in i8 slots,
259 // otherwise some LLVM optimization passes don't work as expected
261 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
262 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
268 let lvalue = addr_of(ccx, val, "const");
269 ccx.const_values().borrow_mut().insert(key, lvalue);
273 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
275 param_substs: &'tcx Substs<'tcx>,
277 -> (ValueRef, Ty<'tcx>) {
278 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
279 &cx.tcx().expr_ty(e));
280 let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args);
281 let mut llconst = llconst;
282 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
283 &cx.tcx().expr_ty_adjusted(e));
284 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
286 Some(ty::AdjustReifyFnPointer) => {
287 // FIXME(#19925) once fn item types are
288 // zero-sized, we'll need to do something here
290 Some(ty::AdjustUnsafeFnPointer) => {
291 // purely a type-level thing
293 Some(ty::AdjustDerefRef(adj)) => {
295 // Save the last autoderef in case we can avoid it.
296 if adj.autoderefs > 0 {
297 for _ in 0..adj.autoderefs-1 {
298 let (dv, dt) = const_deref(cx, llconst, ty);
304 if adj.autoref.is_some() {
305 if adj.autoderefs == 0 {
306 // Don't copy data to do a deref+ref
307 // (i.e., skip the last auto-deref).
308 llconst = addr_of(cx, llconst, "autoref");
309 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
312 let (dv, dt) = const_deref(cx, llconst, ty);
315 // If we derefed a fat pointer then we will have an
316 // open type here. So we need to update the type with
317 // the one returned from const_deref.
321 if let Some(target) = adj.unsize {
322 let target = monomorphize::apply_param_substs(cx.tcx(),
326 let pointee_ty = ty.builtin_deref(true)
327 .expect("consts: unsizing got non-pointer type").ty;
328 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
329 // Normally, the source is a thin pointer and we are
330 // adding extra info to make a fat pointer. The exception
331 // is when we are upcasting an existing object fat pointer
332 // to use a different vtable. In that case, we want to
333 // load out the original data pointer so we can repackage
335 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
336 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
341 let unsized_ty = target.builtin_deref(true)
342 .expect("consts: unsizing got non-pointer target type").ty;
343 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
344 let base = ptrcast(base, ptr_ty);
345 let info = expr::unsized_info(cx, pointee_ty, unsized_ty,
346 old_info, param_substs);
348 if old_info.is_none() {
349 let prev_const = cx.const_unsized().borrow_mut()
350 .insert(base, llconst);
351 assert!(prev_const.is_none() || prev_const == Some(llconst));
353 assert_eq!(abi::FAT_PTR_ADDR, 0);
354 assert_eq!(abi::FAT_PTR_EXTRA, 1);
355 llconst = C_struct(cx, &[base, info], false);
361 let llty = type_of::sizing_type_of(cx, ety_adjusted);
362 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
363 let tsize = machine::llsize_of_alloc(cx, llty);
365 cx.sess().abort_if_errors();
367 // FIXME these values could use some context
368 llvm::LLVMDumpValue(llconst);
369 llvm::LLVMDumpValue(C_undef(llty));
371 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
375 (llconst, ety_adjusted)
378 fn check_unary_expr_validity(cx: &CrateContext, e: &ast::Expr, t: Ty,
380 // The only kind of unary expression that we check for validity
381 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
382 if let ast::ExprUnary(ast::UnNeg, ref inner_e) = e.node {
384 // An unfortunate special case: we parse e.g. -128 as a
385 // negation of the literal 128, which means if we're expecting
386 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
387 // 128 will have already overflowed to -128, and so then the
388 // constant evaluator thinks we're trying to negate -128.
390 // Catch this up front by looking for ExprLit directly,
391 // and just accepting it.
392 if let ast::ExprLit(_) = inner_e.node { return; }
394 let result = match t.sty {
395 ty::TyInt(int_type) => {
396 let input = match const_to_opt_int(te) {
400 const_int_checked_neg(
401 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
403 ty::TyUint(uint_type) => {
404 let input = match const_to_opt_uint(te) {
408 const_uint_checked_neg(
409 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
414 // We do not actually care about a successful result.
415 if let Err(err) = result {
416 cx.tcx().sess.span_err(e.span, &err.description());
421 fn check_binary_expr_validity(cx: &CrateContext, e: &ast::Expr, t: Ty,
422 te1: ValueRef, te2: ValueRef) {
423 let b = if let ast::ExprBinary(b, _, _) = e.node { b } else { return };
425 let result = match t.sty {
426 ty::TyInt(int_type) => {
427 let (lhs, rhs) = match (const_to_opt_int(te1),
428 const_to_opt_int(te2)) {
429 (Some(v1), Some(v2)) => (v1, v2),
433 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
435 ast::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
436 ast::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
437 ast::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
438 ast::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
439 ast::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
440 ast::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
441 ast::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
445 ty::TyUint(uint_type) => {
446 let (lhs, rhs) = match (const_to_opt_uint(te1),
447 const_to_opt_uint(te2)) {
448 (Some(v1), Some(v2)) => (v1, v2),
452 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
454 ast::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
455 ast::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
456 ast::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
457 ast::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
458 ast::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
459 ast::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
460 ast::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
466 // We do not actually care about a successful result.
467 if let Err(err) = result {
468 cx.tcx().sess.span_err(e.span, &err.description());
472 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
475 param_substs: &'tcx Substs<'tcx>,
479 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
484 let map_list = |exprs: &[P<ast::Expr>]| -> Vec<ValueRef> {
486 .map(|e| const_expr(cx, &**e, param_substs, fn_args).0)
489 let _icx = push_ctxt("const_expr");
491 ast::ExprLit(ref lit) => {
492 const_lit(cx, e, &**lit)
494 ast::ExprBinary(b, ref e1, ref e2) => {
495 /* Neither type is bottom, and we expect them to be unified
496 * already, so the following is safe. */
497 let (te1, ty) = const_expr(cx, &**e1, param_substs, fn_args);
498 debug!("const_expr_unadjusted: te1={}, ty={:?}",
499 cx.tn().val_to_string(te1),
501 let is_simd = ty.is_simd(cx.tcx());
502 let intype = if is_simd {
503 ty.simd_type(cx.tcx())
507 let is_float = intype.is_fp();
508 let signed = intype.is_signed();
510 let (te2, _) = const_expr(cx, &**e2, param_substs, fn_args);
512 check_binary_expr_validity(cx, e, ty, te1, te2);
514 unsafe { match b.node {
515 ast::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
516 ast::BiAdd => llvm::LLVMConstAdd(te1, te2),
518 ast::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
519 ast::BiSub => llvm::LLVMConstSub(te1, te2),
521 ast::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
522 ast::BiMul => llvm::LLVMConstMul(te1, te2),
524 ast::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
525 ast::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
526 ast::BiDiv => llvm::LLVMConstUDiv(te1, te2),
528 ast::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
529 ast::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
530 ast::BiRem => llvm::LLVMConstURem(te1, te2),
532 ast::BiAnd => llvm::LLVMConstAnd(te1, te2),
533 ast::BiOr => llvm::LLVMConstOr(te1, te2),
534 ast::BiBitXor => llvm::LLVMConstXor(te1, te2),
535 ast::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
536 ast::BiBitOr => llvm::LLVMConstOr(te1, te2),
538 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
539 llvm::LLVMConstShl(te1, te2)
542 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
543 if signed { llvm::LLVMConstAShr(te1, te2) }
544 else { llvm::LLVMConstLShr(te1, te2) }
546 ast::BiEq | ast::BiNe | ast::BiLt | ast::BiLe | ast::BiGt | ast::BiGe => {
548 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
549 ConstFCmp(cmp, te1, te2)
551 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
552 let bool_val = ConstICmp(cmp, te1, te2);
554 // LLVM outputs an `< size x i1 >`, so we need to perform
555 // a sign extension to get the correctly sized type.
556 llvm::LLVMConstIntCast(bool_val, val_ty(te1).to_ref(), True)
562 } } // unsafe { match b.node {
564 ast::ExprUnary(u, ref inner_e) => {
565 let (te, ty) = const_expr(cx, &**inner_e, param_substs, fn_args);
567 check_unary_expr_validity(cx, e, ty, te);
569 let is_float = ty.is_fp();
571 ast::UnUniq | ast::UnDeref => const_deref(cx, te, ty).0,
572 ast::UnNot => llvm::LLVMConstNot(te),
573 ast::UnNeg if is_float => llvm::LLVMConstFNeg(te),
574 ast::UnNeg => llvm::LLVMConstNeg(te),
577 ast::ExprField(ref base, field) => {
578 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
579 let brepr = adt::represent_type(cx, bt);
580 expr::with_field_tys(cx.tcx(), bt, None, |discr, field_tys| {
581 let ix = cx.tcx().field_idx_strict(field.node.name, field_tys);
582 adt::const_get_field(cx, &*brepr, bv, discr, ix)
585 ast::ExprTupField(ref base, idx) => {
586 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
587 let brepr = adt::represent_type(cx, bt);
588 expr::with_field_tys(cx.tcx(), bt, None, |discr, _| {
589 adt::const_get_field(cx, &*brepr, bv, 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 const_eval::eval_const_expr_partial(cx.tcx(), &**index, None) {
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::mt{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(cx.tcx(), t_expr).expect("bad input type for cast"),
666 CastTy::from_ty(cx.tcx(), 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 expr::with_field_tys(cx.tcx(), ety, Some(e.id), |discr, field_tys| {
750 let cs = field_tys.iter().enumerate()
751 .map(|(ix, &field_ty)| {
752 match (fs.iter().find(|f| field_ty.name == f.ident.node.name), base_val) {
753 (Some(ref f), _) => const_expr(cx, &*f.expr, param_substs, fn_args).0,
754 (_, Some((bv, _))) => adt::const_get_field(cx, &*repr, bv, discr, ix),
755 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
757 }).collect::<Vec<_>>();
758 if ety.is_simd(cx.tcx()) {
761 adt::trans_const(cx, &*repr, discr, &cs[..])
765 ast::ExprVec(ref es) => {
766 let unit_ty = ety.sequence_element_type(cx.tcx());
767 let llunitty = type_of::type_of(cx, unit_ty);
769 .map(|e| const_expr(cx, &**e, param_substs, fn_args).0)
770 .collect::<Vec<_>>();
771 // If the vector contains enums, an LLVM array won't work.
772 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
773 C_struct(cx, &vs[..], false)
775 C_array(llunitty, &vs[..])
778 ast::ExprRepeat(ref elem, ref count) => {
779 let unit_ty = ety.sequence_element_type(cx.tcx());
780 let llunitty = type_of::type_of(cx, unit_ty);
781 let n = cx.tcx().eval_repeat_count(count);
782 let unit_val = const_expr(cx, &**elem, param_substs, fn_args).0;
783 let vs: Vec<_> = repeat(unit_val).take(n).collect();
784 if val_ty(unit_val) != llunitty {
785 C_struct(cx, &vs[..], false)
787 C_array(llunitty, &vs[..])
790 ast::ExprPath(..) => {
791 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
793 def::DefLocal(id) => {
794 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
797 cx.sess().span_bug(e.span, "const fn argument not found")
800 def::DefFn(..) | def::DefMethod(..) => {
801 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
803 def::DefConst(def_id) | def::DefAssociatedConst(def_id, _) => {
804 const_deref_ptr(cx, get_const_val(cx, def_id, e))
806 def::DefVariant(enum_did, variant_did, _) => {
807 let vinfo = cx.tcx().enum_variant_with_id(enum_did, variant_did);
808 if !vinfo.args.is_empty() {
810 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
813 let repr = adt::represent_type(cx, ety);
814 adt::trans_const(cx, &*repr, vinfo.disr_val, &[])
817 def::DefStruct(_) => {
818 if let ty::TyBareFn(..) = ety.sty {
820 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
823 C_null(type_of::type_of(cx, ety))
827 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
832 ast::ExprCall(ref callee, ref args) => {
833 let mut callee = &**callee;
835 callee = match callee.node {
836 ast::ExprParen(ref inner) => &**inner,
837 ast::ExprBlock(ref block) => match block.expr {
838 Some(ref tail) => &**tail,
844 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
845 let arg_vals = map_list(args);
847 def::DefFn(did, _) | def::DefMethod(did, _) => {
848 const_fn_call(cx, ExprId(callee.id), did, &arg_vals, param_substs)
850 def::DefStruct(_) => {
851 if ety.is_simd(cx.tcx()) {
852 C_vector(&arg_vals[..])
854 let repr = adt::represent_type(cx, ety);
855 adt::trans_const(cx, &*repr, 0, &arg_vals[..])
858 def::DefVariant(enum_did, variant_did, _) => {
859 let repr = adt::represent_type(cx, ety);
860 let vinfo = cx.tcx().enum_variant_with_id(enum_did, variant_did);
866 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
869 ast::ExprMethodCall(_, _, ref args) => {
870 let arg_vals = map_list(args);
871 let method_call = ty::MethodCall::expr(e.id);
872 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
873 const_fn_call(cx, MethodCallKey(method_call),
874 method_did, &arg_vals, param_substs)
876 ast::ExprParen(ref e) => const_expr(cx, &**e, param_substs, fn_args).0,
877 ast::ExprBlock(ref block) => {
879 Some(ref expr) => const_expr(cx, &**expr, param_substs, fn_args).0,
883 ast::ExprClosure(_, ref decl, ref body) => {
884 closure::trans_closure_expr(closure::Dest::Ignore(cx),
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"),
896 pub fn trans_static(ccx: &CrateContext, m: ast::Mutability, id: ast::NodeId) -> ValueRef {
898 let _icx = push_ctxt("trans_static");
899 let g = base::get_item_val(ccx, id);
900 // At this point, get_item_val has already translated the
901 // constant's initializer to determine its LLVM type.
902 let v = ccx.static_values().borrow().get(&id).unwrap().clone();
903 // boolean SSA values are i1, but they have to be stored in i8 slots,
904 // otherwise some LLVM optimization passes don't work as expected
905 let v = if llvm::LLVMTypeOf(v) == Type::i1(ccx).to_ref() {
906 llvm::LLVMConstZExt(v, Type::i8(ccx).to_ref())
910 llvm::LLVMSetInitializer(g, v);
912 // As an optimization, all shared statics which do not have interior
913 // mutability are placed into read-only memory.
914 if m != ast::MutMutable {
915 let node_ty = ccx.tcx().node_id_to_type(id);
916 let tcontents = node_ty.type_contents(ccx.tcx());
917 if !tcontents.interior_unsafe() {
918 llvm::LLVMSetGlobalConstant(g, True);
921 debuginfo::create_global_var_metadata(ccx, id, g);
926 fn get_static_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, did: ast::DefId,
927 ty: Ty<'tcx>) -> ValueRef {
928 if ast_util::is_local(did) { return base::get_item_val(ccx, did.node) }
929 base::trans_external_path(ccx, did, ty)