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 middle::def_id::{DefId, LOCAL_CRATE};
29 use trans::{adt, closure, debuginfo, expr, inline, machine};
30 use trans::base::{self, push_ctxt};
33 use trans::monomorphize;
34 use trans::type_::Type;
36 use middle::subst::Substs;
37 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
38 use middle::ty::adjustment::AdjustUnsafeFnPointer;
39 use middle::ty::{self, Ty};
40 use middle::ty::cast::{CastTy,IntTy};
41 use util::nodemap::NodeMap;
44 use rustc_front::attr;
46 use std::ffi::{CStr, CString};
49 use syntax::parse::token;
52 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
54 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &hir::Lit)
56 let _icx = push_ctxt("trans_lit");
57 debug!("const_lit: {:?}", lit);
59 hir::LitByte(b) => C_integral(Type::uint_from_ty(cx, hir::TyU8), b as u64, false),
60 hir::LitChar(i) => C_integral(Type::char(cx), i as u64, false),
61 hir::LitInt(i, hir::SignedIntLit(t, _)) => {
62 C_integral(Type::int_from_ty(cx, t), i, true)
64 hir::LitInt(u, hir::UnsignedIntLit(t)) => {
65 C_integral(Type::uint_from_ty(cx, t), u, false)
67 hir::LitInt(i, hir::UnsuffixedIntLit(_)) => {
68 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
69 match lit_int_ty.sty {
71 C_integral(Type::int_from_ty(cx, t), i as u64, true)
74 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
76 _ => cx.sess().span_bug(lit.span,
77 &format!("integer literal has type {:?} (expected int \
82 hir::LitFloat(ref fs, t) => {
83 C_floating(&fs, Type::float_from_ty(cx, t))
85 hir::LitFloatUnsuffixed(ref fs) => {
86 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
87 match lit_float_ty.sty {
89 C_floating(&fs, Type::float_from_ty(cx, t))
92 cx.sess().span_bug(lit.span,
93 "floating point literal doesn't have the right type");
97 hir::LitBool(b) => C_bool(cx, b),
98 hir::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()),
99 hir::LitByteStr(ref data) => {
100 addr_of(cx, C_bytes(cx, &data[..]), "byte_str")
105 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
107 llvm::LLVMConstPointerCast(val, ty.to_ref())
111 fn addr_of_mut(ccx: &CrateContext,
116 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
117 // counter? Also most other uses of gensym in trans.
118 let gsym = token::gensym("_");
119 let name = format!("{}{}", kind, gsym.usize());
120 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
121 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
123 llvm::LLVMSetInitializer(gv, cv);
124 SetLinkage(gv, InternalLinkage);
125 SetUnnamedAddr(gv, true);
130 pub fn addr_of(ccx: &CrateContext,
134 match ccx.const_globals().borrow().get(&cv) {
135 Some(&gv) => return gv,
138 let gv = addr_of_mut(ccx, cv, kind);
140 llvm::LLVMSetGlobalConstant(gv, True);
142 ccx.const_globals().borrow_mut().insert(cv, gv);
146 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
147 let v = match cx.const_unsized().borrow().get(&v) {
152 llvm::LLVMGetInitializer(v)
156 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
159 -> (ValueRef, Ty<'tcx>) {
160 match ty.builtin_deref(true, ty::NoPreference) {
162 if type_is_sized(cx.tcx(), mt.ty) {
163 (const_deref_ptr(cx, v), mt.ty)
165 // Derefing a fat pointer does not change the representation,
166 // just the type to the unsized contents.
171 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
177 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
178 node: ExprOrMethodCall,
180 arg_vals: &[ValueRef],
181 param_substs: &'tcx Substs<'tcx>) -> ValueRef {
182 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
183 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
185 let args = &fn_like.decl().inputs;
186 assert_eq!(args.len(), arg_vals.len());
188 let arg_ids = args.iter().map(|arg| arg.pat.id);
189 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
191 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
192 match fn_like.body().expr {
194 const_expr(ccx, &**expr, substs, Some(&fn_args)).0
200 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
202 ref_expr: &hir::Expr)
204 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
206 if def_id.krate != LOCAL_CRATE {
207 ccx.sess().span_bug(ref_expr.span,
208 "cross crate constant could not be inlined");
211 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id)) {
212 Some(ref expr) => expr,
214 ccx.sess().span_bug(ref_expr.span, "constant item not found")
219 fn get_const_val(ccx: &CrateContext,
221 ref_expr: &hir::Expr) -> ValueRef {
222 let expr = get_const_expr(ccx, def_id, ref_expr);
223 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
224 get_const_expr_as_global(ccx, expr, check_const::ConstQualif::empty(), empty_substs)
227 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
229 qualif: check_const::ConstQualif,
230 param_substs: &'tcx Substs<'tcx>)
232 debug!("get_const_expr_as_global: {:?}", expr.id);
233 // Special-case constants to cache a common global for all uses.
235 hir::ExprPath(..) => {
236 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
238 def::DefConst(def_id) | def::DefAssociatedConst(def_id) => {
239 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
240 debug!("get_const_expr_as_global ({:?}): found const {:?}",
242 return get_const_val(ccx, def_id, expr);
251 let key = (expr.id, param_substs);
252 match ccx.const_values().borrow().get(&key) {
253 Some(&val) => return val,
256 let val = if qualif.intersects(check_const::ConstQualif::NON_STATIC_BORROWS) {
257 // Avoid autorefs as they would create global instead of stack
258 // references, even when only the latter are correct.
259 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
260 &ccx.tcx().expr_ty(expr));
261 const_expr_unadjusted(ccx, expr, ty, param_substs, None)
263 const_expr(ccx, expr, param_substs, None).0
266 // boolean SSA values are i1, but they have to be stored in i8 slots,
267 // otherwise some LLVM optimization passes don't work as expected
269 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
270 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
276 let lvalue = addr_of(ccx, val, "const");
277 ccx.const_values().borrow_mut().insert(key, lvalue);
281 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
283 param_substs: &'tcx Substs<'tcx>,
285 -> (ValueRef, Ty<'tcx>) {
286 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
287 &cx.tcx().expr_ty(e));
288 let llconst = const_expr_unadjusted(cx, e, ety, param_substs, fn_args);
289 let mut llconst = llconst;
290 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
291 &cx.tcx().expr_ty_adjusted(e));
292 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
294 Some(AdjustReifyFnPointer) => {
295 // FIXME(#19925) once fn item types are
296 // zero-sized, we'll need to do something here
298 Some(AdjustUnsafeFnPointer) => {
299 // purely a type-level thing
301 Some(AdjustDerefRef(adj)) => {
303 // Save the last autoderef in case we can avoid it.
304 if adj.autoderefs > 0 {
305 for _ in 0..adj.autoderefs-1 {
306 let (dv, dt) = const_deref(cx, llconst, ty);
312 if adj.autoref.is_some() {
313 if adj.autoderefs == 0 {
314 // Don't copy data to do a deref+ref
315 // (i.e., skip the last auto-deref).
316 llconst = addr_of(cx, llconst, "autoref");
317 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
320 let (dv, dt) = const_deref(cx, llconst, ty);
323 // If we derefed a fat pointer then we will have an
324 // open type here. So we need to update the type with
325 // the one returned from const_deref.
329 if let Some(target) = adj.unsize {
330 let target = monomorphize::apply_param_substs(cx.tcx(),
334 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
335 .expect("consts: unsizing got non-pointer type").ty;
336 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
337 // Normally, the source is a thin pointer and we are
338 // adding extra info to make a fat pointer. The exception
339 // is when we are upcasting an existing object fat pointer
340 // to use a different vtable. In that case, we want to
341 // load out the original data pointer so we can repackage
343 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
344 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
349 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
350 .expect("consts: unsizing got non-pointer target type").ty;
351 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
352 let base = ptrcast(base, ptr_ty);
353 let info = expr::unsized_info(cx, pointee_ty, unsized_ty,
354 old_info, param_substs);
356 if old_info.is_none() {
357 let prev_const = cx.const_unsized().borrow_mut()
358 .insert(base, llconst);
359 assert!(prev_const.is_none() || prev_const == Some(llconst));
361 assert_eq!(abi::FAT_PTR_ADDR, 0);
362 assert_eq!(abi::FAT_PTR_EXTRA, 1);
363 llconst = C_struct(cx, &[base, info], false);
369 let llty = type_of::sizing_type_of(cx, ety_adjusted);
370 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
371 let tsize = machine::llsize_of_alloc(cx, llty);
373 cx.sess().abort_if_errors();
375 // FIXME these values could use some context
376 llvm::LLVMDumpValue(llconst);
377 llvm::LLVMDumpValue(C_undef(llty));
379 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
383 (llconst, ety_adjusted)
386 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
388 // The only kind of unary expression that we check for validity
389 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
390 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
392 // An unfortunate special case: we parse e.g. -128 as a
393 // negation of the literal 128, which means if we're expecting
394 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
395 // 128 will have already overflowed to -128, and so then the
396 // constant evaluator thinks we're trying to negate -128.
398 // Catch this up front by looking for ExprLit directly,
399 // and just accepting it.
400 if let hir::ExprLit(_) = inner_e.node { return; }
402 let result = match t.sty {
403 ty::TyInt(int_type) => {
404 let input = match const_to_opt_int(te) {
408 const_int_checked_neg(
409 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
411 ty::TyUint(uint_type) => {
412 let input = match const_to_opt_uint(te) {
416 const_uint_checked_neg(
417 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
422 // We do not actually care about a successful result.
423 if let Err(err) = result {
424 cx.tcx().sess.span_err(e.span, &err.description());
429 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
430 te1: ValueRef, te2: ValueRef) {
431 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { return };
433 let result = match t.sty {
434 ty::TyInt(int_type) => {
435 let (lhs, rhs) = match (const_to_opt_int(te1),
436 const_to_opt_int(te2)) {
437 (Some(v1), Some(v2)) => (v1, v2),
441 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
443 hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
444 hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
445 hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
446 hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
447 hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
448 hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
449 hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
453 ty::TyUint(uint_type) => {
454 let (lhs, rhs) = match (const_to_opt_uint(te1),
455 const_to_opt_uint(te2)) {
456 (Some(v1), Some(v2)) => (v1, v2),
460 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
462 hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
463 hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
464 hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
465 hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
466 hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
467 hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
468 hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
474 // We do not actually care about a successful result.
475 if let Err(err) = result {
476 cx.tcx().sess.span_err(e.span, &err.description());
480 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
483 param_substs: &'tcx Substs<'tcx>,
487 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
492 let map_list = |exprs: &[P<hir::Expr>]| -> Vec<ValueRef> {
494 .map(|e| const_expr(cx, &**e, param_substs, fn_args).0)
497 let _icx = push_ctxt("const_expr");
499 hir::ExprLit(ref lit) => {
500 const_lit(cx, e, &**lit)
502 hir::ExprBinary(b, ref e1, ref e2) => {
503 /* Neither type is bottom, and we expect them to be unified
504 * already, so the following is safe. */
505 let (te1, ty) = const_expr(cx, &**e1, param_substs, fn_args);
506 debug!("const_expr_unadjusted: te1={}, ty={:?}",
507 cx.tn().val_to_string(te1),
509 assert!(!ty.is_simd());
510 let is_float = ty.is_fp();
511 let signed = ty.is_signed();
513 let (te2, _) = const_expr(cx, &**e2, param_substs, fn_args);
515 check_binary_expr_validity(cx, e, ty, te1, te2);
517 unsafe { match b.node {
518 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
519 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
521 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
522 hir::BiSub => llvm::LLVMConstSub(te1, te2),
524 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
525 hir::BiMul => llvm::LLVMConstMul(te1, te2),
527 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
528 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
529 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
531 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
532 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
533 hir::BiRem => llvm::LLVMConstURem(te1, te2),
535 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
536 hir::BiOr => llvm::LLVMConstOr(te1, te2),
537 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
538 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
539 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
541 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
542 llvm::LLVMConstShl(te1, te2)
545 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
546 if signed { llvm::LLVMConstAShr(te1, te2) }
547 else { llvm::LLVMConstLShr(te1, te2) }
549 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
551 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
552 ConstFCmp(cmp, te1, te2)
554 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
555 ConstICmp(cmp, te1, te2)
558 } } // unsafe { match b.node {
560 hir::ExprUnary(u, ref inner_e) => {
561 let (te, ty) = const_expr(cx, &**inner_e, param_substs, fn_args);
563 check_unary_expr_validity(cx, e, ty, te);
565 let is_float = ty.is_fp();
567 hir::UnUniq | hir::UnDeref => const_deref(cx, te, ty).0,
568 hir::UnNot => llvm::LLVMConstNot(te),
569 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
570 hir::UnNeg => llvm::LLVMConstNeg(te),
573 hir::ExprField(ref base, field) => {
574 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
575 let brepr = adt::represent_type(cx, bt);
576 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
577 let ix = vinfo.field_index(field.node.name);
578 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, ix)
580 hir::ExprTupField(ref base, idx) => {
581 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
582 let brepr = adt::represent_type(cx, bt);
583 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
584 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, idx.node)
587 hir::ExprIndex(ref base, ref index) => {
588 let (bv, bt) = const_expr(cx, &**base, param_substs, fn_args);
589 let iv = match eval_const_expr_partial(cx.tcx(), &index, ExprTypeChecked) {
590 Ok(ConstVal::Int(i)) => i as u64,
591 Ok(ConstVal::Uint(u)) => u,
592 _ => cx.sess().span_bug(index.span,
593 "index is not an integer-constant expression")
595 let (arr, len) = match bt.sty {
596 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
597 ty::TySlice(_) | ty::TyStr => {
598 let e1 = const_get_elt(cx, bv, &[0]);
599 (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1]))
601 ty::TyRef(_, mt) => match mt.ty.sty {
602 ty::TyArray(_, u) => {
603 (const_deref_ptr(cx, bv), C_uint(cx, u))
605 _ => cx.sess().span_bug(base.span,
606 &format!("index-expr base must be a vector \
607 or string type, found {:?}",
610 _ => cx.sess().span_bug(base.span,
611 &format!("index-expr base must be a vector \
612 or string type, found {:?}",
616 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
617 let len = match bt.sty {
618 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
628 // FIXME #3170: report this earlier on in the const-eval
629 // pass. Reporting here is a bit late.
630 cx.sess().span_err(e.span,
631 "const index-expr is out of bounds");
632 C_undef(type_of::type_of(cx, bt).element_type())
634 const_get_elt(cx, arr, &[iv as c_uint])
637 hir::ExprCast(ref base, _) => {
639 let llty = type_of::type_of(cx, t_cast);
640 let (v, t_expr) = const_expr(cx, &**base, param_substs, fn_args);
641 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
642 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
645 if type_is_fat_ptr(cx.tcx(), t_expr) {
646 // Fat pointer casts.
648 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
649 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
650 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
652 if type_is_fat_ptr(cx.tcx(), t_cast) {
653 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
654 return C_struct(cx, &[addr, info], false)
660 CastTy::from_ty(t_expr).expect("bad input type for cast"),
661 CastTy::from_ty(t_cast).expect("bad output type for cast"),
663 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
664 let repr = adt::represent_type(cx, t_expr);
665 let discr = adt::const_get_discrim(cx, &*repr, v);
666 let iv = C_integral(cx.int_type(), discr, false);
667 let s = adt::is_discr_signed(&*repr) as Bool;
668 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
670 (CastTy::Int(_), CastTy::Int(_)) => {
671 let s = t_expr.is_signed() as Bool;
672 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
674 (CastTy::Int(_), CastTy::Float) => {
675 if t_expr.is_signed() {
676 llvm::LLVMConstSIToFP(v, llty.to_ref())
678 llvm::LLVMConstUIToFP(v, llty.to_ref())
681 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
682 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
683 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
684 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
685 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
688 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
689 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
690 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
691 llvm::LLVMConstPtrToInt(v, llty.to_ref())
694 cx.sess().impossible_case(e.span,
695 "bad combination of types for cast")
697 } } // unsafe { match ( ... ) {
699 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
700 // If this is the address of some static, then we need to return
701 // the actual address of the static itself (short circuit the rest
706 hir::ExprParen(ref sub) => cur = sub,
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.ident.node.name), 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::ExprParen(ref inner) => &**inner,
834 hir::ExprBlock(ref block) => match block.expr {
835 Some(ref tail) => &**tail,
841 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
842 let arg_vals = map_list(args);
844 def::DefFn(did, _) | def::DefMethod(did) => {
845 const_fn_call(cx, ExprId(callee.id), did, &arg_vals, param_substs)
847 def::DefStruct(_) => {
849 C_vector(&arg_vals[..])
851 let repr = adt::represent_type(cx, ety);
852 adt::trans_const(cx, &*repr, 0, &arg_vals[..])
855 def::DefVariant(enum_did, variant_did, _) => {
856 let repr = adt::represent_type(cx, ety);
857 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
863 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
866 hir::ExprMethodCall(_, _, ref args) => {
867 let arg_vals = map_list(args);
868 let method_call = ty::MethodCall::expr(e.id);
869 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
870 const_fn_call(cx, MethodCallKey(method_call),
871 method_did, &arg_vals, param_substs)
873 hir::ExprParen(ref e) => const_expr(cx, &**e, param_substs, fn_args).0,
874 hir::ExprBlock(ref block) => {
876 Some(ref expr) => const_expr(cx, &**expr, param_substs, fn_args).0,
880 hir::ExprClosure(_, ref decl, ref body) => {
882 ty::TyClosure(_, ref substs) => {
883 closure::trans_closure_expr(closure::Dest::Ignore(cx), decl,
889 &format!("bad type for closure expr: {:?}", ety))
891 C_null(type_of::type_of(cx, ety))
893 _ => cx.sess().span_bug(e.span,
894 "bad constant expression type in consts::const_expr"),
897 pub fn trans_static(ccx: &CrateContext,
901 attrs: &Vec<hir::Attribute>)
904 let _icx = push_ctxt("trans_static");
905 let g = base::get_item_val(ccx, id);
907 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
908 let (v, _) = const_expr(ccx, expr, empty_substs, None);
910 // boolean SSA values are i1, but they have to be stored in i8 slots,
911 // otherwise some LLVM optimization passes don't work as expected
912 let mut val_llty = llvm::LLVMTypeOf(v);
913 let v = if val_llty == Type::i1(ccx).to_ref() {
914 val_llty = Type::i8(ccx).to_ref();
915 llvm::LLVMConstZExt(v, val_llty)
920 let ty = ccx.tcx().node_id_to_type(id);
921 let llty = type_of::type_of(ccx, ty);
922 let g = if val_llty == llty.to_ref() {
925 // If we created the global with the wrong type,
927 let empty_string = CString::new("").unwrap();
928 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
929 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
930 llvm::LLVMSetValueName(g, empty_string.as_ptr());
931 let new_g = llvm::LLVMGetOrInsertGlobal(
932 ccx.llmod(), name_string.as_ptr(), val_llty);
933 // To avoid breaking any invariants, we leave around the old
934 // global for the moment; we'll replace all references to it
935 // with the new global later. (See base::trans_crate.)
936 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
939 llvm::LLVMSetInitializer(g, v);
941 // As an optimization, all shared statics which do not have interior
942 // mutability are placed into read-only memory.
943 if m != hir::MutMutable {
944 let tcontents = ty.type_contents(ccx.tcx());
945 if !tcontents.interior_unsafe() {
946 llvm::LLVMSetGlobalConstant(g, llvm::True);
950 debuginfo::create_global_var_metadata(ccx, id, g);
952 if attr::contains_name(attrs,
954 llvm::set_thread_local(g, true);
961 fn get_static_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
965 if did.is_local() { return base::get_item_val(ccx, did.node) }
966 base::trans_external_path(ccx, did, ty)