1 // Copyright 2012 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
14 use llvm::{ConstFCmp, ConstICmp, SetLinkage, SetUnnamedAddr};
15 use llvm::{InternalLinkage, ValueRef, Bool, True};
16 use middle::const_qualif::ConstQualif;
17 use middle::cstore::LOCAL_CRATE;
18 use middle::const_eval::{self, ConstVal, ConstEvalErr};
19 use middle::const_eval::{const_int_checked_neg, const_uint_checked_neg};
20 use middle::const_eval::{const_int_checked_add, const_uint_checked_add};
21 use middle::const_eval::{const_int_checked_sub, const_uint_checked_sub};
22 use middle::const_eval::{const_int_checked_mul, const_uint_checked_mul};
23 use middle::const_eval::{const_int_checked_div, const_uint_checked_div};
24 use middle::const_eval::{const_int_checked_rem, const_uint_checked_rem};
25 use middle::const_eval::{const_int_checked_shl, const_uint_checked_shl};
26 use middle::const_eval::{const_int_checked_shr, const_uint_checked_shr};
27 use middle::const_eval::EvalHint::ExprTypeChecked;
28 use middle::const_eval::eval_const_expr_partial;
30 use middle::def_id::DefId;
31 use trans::{adt, closure, debuginfo, expr, inline, machine};
32 use trans::base::{self, push_ctxt};
33 use trans::common::{self, type_is_sized, ExprOrMethodCall, node_id_substs, C_nil, const_get_elt};
34 use trans::common::{CrateContext, C_integral, C_floating, C_bool, C_str_slice, C_bytes, val_ty};
35 use trans::common::{C_struct, C_undef, const_to_opt_int, const_to_opt_uint, VariantInfo, C_uint};
36 use trans::common::{type_is_fat_ptr, Field, C_vector, C_array, C_null, ExprId, MethodCallKey};
38 use trans::monomorphize;
39 use trans::type_::Type;
42 use middle::subst::Substs;
43 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
44 use middle::ty::adjustment::AdjustUnsafeFnPointer;
45 use middle::ty::{self, Ty};
46 use middle::ty::cast::{CastTy,IntTy};
47 use util::nodemap::NodeMap;
51 use std::ffi::{CStr, CString};
56 use syntax::parse::token;
59 pub type FnArgMap<'a> = Option<&'a NodeMap<ValueRef>>;
61 pub fn const_lit(cx: &CrateContext, e: &hir::Expr, lit: &ast::Lit)
63 let _icx = push_ctxt("trans_lit");
64 debug!("const_lit: {:?}", lit);
66 ast::LitByte(b) => C_integral(Type::uint_from_ty(cx, ast::TyU8), b as u64, false),
67 ast::LitChar(i) => C_integral(Type::char(cx), i as u64, false),
68 ast::LitInt(i, ast::SignedIntLit(t, _)) => {
69 C_integral(Type::int_from_ty(cx, t), i, true)
71 ast::LitInt(u, ast::UnsignedIntLit(t)) => {
72 C_integral(Type::uint_from_ty(cx, t), u, false)
74 ast::LitInt(i, ast::UnsuffixedIntLit(_)) => {
75 let lit_int_ty = cx.tcx().node_id_to_type(e.id);
76 match lit_int_ty.sty {
78 C_integral(Type::int_from_ty(cx, t), i as u64, true)
81 C_integral(Type::uint_from_ty(cx, t), i as u64, false)
83 _ => cx.sess().span_bug(lit.span,
84 &format!("integer literal has type {:?} (expected int \
89 ast::LitFloat(ref fs, t) => {
90 C_floating(&fs, Type::float_from_ty(cx, t))
92 ast::LitFloatUnsuffixed(ref fs) => {
93 let lit_float_ty = cx.tcx().node_id_to_type(e.id);
94 match lit_float_ty.sty {
96 C_floating(&fs, Type::float_from_ty(cx, t))
99 cx.sess().span_bug(lit.span,
100 "floating point literal doesn't have the right type");
104 ast::LitBool(b) => C_bool(cx, b),
105 ast::LitStr(ref s, _) => C_str_slice(cx, (*s).clone()),
106 ast::LitByteStr(ref data) => {
107 addr_of(cx, C_bytes(cx, &data[..]), 1, "byte_str")
112 pub fn ptrcast(val: ValueRef, ty: Type) -> ValueRef {
114 llvm::LLVMConstPointerCast(val, ty.to_ref())
118 fn addr_of_mut(ccx: &CrateContext,
120 align: machine::llalign,
124 // FIXME: this totally needs a better name generation scheme, perhaps a simple global
125 // counter? Also most other uses of gensym in trans.
126 let gsym = token::gensym("_");
127 let name = format!("{}{}", kind, gsym.0);
128 let gv = declare::define_global(ccx, &name[..], val_ty(cv)).unwrap_or_else(||{
129 ccx.sess().bug(&format!("symbol `{}` is already defined", name));
131 llvm::LLVMSetInitializer(gv, cv);
132 llvm::LLVMSetAlignment(gv, align);
133 SetLinkage(gv, InternalLinkage);
134 SetUnnamedAddr(gv, true);
139 pub fn addr_of(ccx: &CrateContext,
141 align: machine::llalign,
144 match ccx.const_globals().borrow().get(&cv) {
147 // Upgrade the alignment in cases where the same constant is used with different
148 // alignment requirements
149 if align > llvm::LLVMGetAlignment(gv) {
150 llvm::LLVMSetAlignment(gv, align);
157 let gv = addr_of_mut(ccx, cv, align, kind);
159 llvm::LLVMSetGlobalConstant(gv, True);
161 ccx.const_globals().borrow_mut().insert(cv, gv);
165 fn const_deref_ptr(cx: &CrateContext, v: ValueRef) -> ValueRef {
166 let v = match cx.const_unsized().borrow().get(&v) {
171 llvm::LLVMGetInitializer(v)
175 fn const_deref<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
178 -> (ValueRef, Ty<'tcx>) {
179 match ty.builtin_deref(true, ty::NoPreference) {
181 if type_is_sized(cx.tcx(), mt.ty) {
182 (const_deref_ptr(cx, v), mt.ty)
184 // Derefing a fat pointer does not change the representation,
185 // just the type to the unsized contents.
190 cx.sess().bug(&format!("unexpected dereferenceable type {:?}",
196 fn const_fn_call<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
197 node: ExprOrMethodCall,
199 arg_vals: &[ValueRef],
200 param_substs: &'tcx Substs<'tcx>,
201 trueconst: TrueConst) -> Result<ValueRef, ConstEvalFailure> {
202 let fn_like = const_eval::lookup_const_fn_by_id(ccx.tcx(), def_id);
203 let fn_like = fn_like.expect("lookup_const_fn_by_id failed in const_fn_call");
205 let args = &fn_like.decl().inputs;
206 assert_eq!(args.len(), arg_vals.len());
208 let arg_ids = args.iter().map(|arg| arg.pat.id);
209 let fn_args = arg_ids.zip(arg_vals.iter().cloned()).collect();
211 let substs = ccx.tcx().mk_substs(node_id_substs(ccx, node, param_substs));
212 match fn_like.body().expr {
214 const_expr(ccx, &**expr, substs, Some(&fn_args), trueconst).map(|(res, _)| res)
216 None => Ok(C_nil(ccx)),
220 pub fn get_const_expr<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
222 ref_expr: &hir::Expr,
223 param_substs: &'tcx Substs<'tcx>)
225 let def_id = inline::maybe_instantiate_inline(ccx, def_id);
227 if def_id.krate != LOCAL_CRATE {
228 ccx.sess().span_bug(ref_expr.span,
229 "cross crate constant could not be inlined");
232 match const_eval::lookup_const_by_id(ccx.tcx(), def_id, Some(ref_expr.id), Some(param_substs)) {
233 Some(ref expr) => expr,
235 ccx.sess().span_bug(ref_expr.span, "constant item not found")
240 pub enum ConstEvalFailure {
241 /// in case the const evaluator failed on something that panic at runtime
242 /// as defined in RFC 1229
243 Runtime(ConstEvalErr),
244 // in case we found a true constant
245 Compiletime(ConstEvalErr),
248 impl ConstEvalFailure {
249 fn into_inner(self) -> ConstEvalErr {
255 pub fn description(&self) -> Cow<str> {
257 &Runtime(ref e) => e.description(),
258 &Compiletime(ref e) => e.description(),
263 #[derive(Copy, Clone)]
268 use self::ConstEvalFailure::*;
270 fn get_const_val<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
272 ref_expr: &hir::Expr,
273 param_substs: &'tcx Substs<'tcx>)
274 -> Result<ValueRef, ConstEvalFailure> {
275 let expr = get_const_expr(ccx, def_id, ref_expr, param_substs);
276 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
277 match get_const_expr_as_global(ccx, expr, ConstQualif::empty(), empty_substs, TrueConst::Yes) {
278 Err(Runtime(err)) => {
279 ccx.tcx().sess.span_err(expr.span, &err.description());
280 Err(Compiletime(err))
286 pub fn get_const_expr_as_global<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
289 param_substs: &'tcx Substs<'tcx>,
290 trueconst: TrueConst)
291 -> Result<ValueRef, ConstEvalFailure> {
292 debug!("get_const_expr_as_global: {:?}", expr.id);
293 // Special-case constants to cache a common global for all uses.
294 if let hir::ExprPath(..) = expr.node {
295 // `def` must be its own statement and cannot be in the `match`
296 // otherwise the `def_map` will be borrowed for the entire match instead
297 // of just to get the `def` value
298 let def = ccx.tcx().def_map.borrow().get(&expr.id).unwrap().full_def();
300 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
301 if !ccx.tcx().tables.borrow().adjustments.contains_key(&expr.id) {
302 debug!("get_const_expr_as_global ({:?}): found const {:?}",
304 return get_const_val(ccx, def_id, expr, param_substs);
311 let key = (expr.id, param_substs);
312 if let Some(&val) = ccx.const_values().borrow().get(&key) {
315 let ty = monomorphize::apply_param_substs(ccx.tcx(), param_substs,
316 &ccx.tcx().expr_ty(expr));
317 let val = if qualif.intersects(ConstQualif::NON_STATIC_BORROWS) {
318 // Avoid autorefs as they would create global instead of stack
319 // references, even when only the latter are correct.
320 try!(const_expr_unadjusted(ccx, expr, ty, param_substs, None, trueconst))
322 try!(const_expr(ccx, expr, param_substs, None, trueconst)).0
325 // boolean SSA values are i1, but they have to be stored in i8 slots,
326 // otherwise some LLVM optimization passes don't work as expected
328 if llvm::LLVMTypeOf(val) == Type::i1(ccx).to_ref() {
329 llvm::LLVMConstZExt(val, Type::i8(ccx).to_ref())
335 let lvalue = addr_of(ccx, val, type_of::align_of(ccx, ty), "const");
336 ccx.const_values().borrow_mut().insert(key, lvalue);
340 pub fn const_expr<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
342 param_substs: &'tcx Substs<'tcx>,
344 trueconst: TrueConst)
345 -> Result<(ValueRef, Ty<'tcx>), ConstEvalFailure> {
346 let ety = monomorphize::apply_param_substs(cx.tcx(), param_substs,
347 &cx.tcx().expr_ty(e));
348 let llconst = try!(const_expr_unadjusted(cx, e, ety, param_substs, fn_args, trueconst));
349 let mut llconst = llconst;
350 let mut ety_adjusted = monomorphize::apply_param_substs(cx.tcx(), param_substs,
351 &cx.tcx().expr_ty_adjusted(e));
352 let opt_adj = cx.tcx().tables.borrow().adjustments.get(&e.id).cloned();
354 Some(AdjustReifyFnPointer) => {
355 // FIXME(#19925) once fn item types are
356 // zero-sized, we'll need to do something here
358 Some(AdjustUnsafeFnPointer) => {
359 // purely a type-level thing
361 Some(AdjustDerefRef(adj)) => {
363 // Save the last autoderef in case we can avoid it.
364 if adj.autoderefs > 0 {
365 for _ in 0..adj.autoderefs-1 {
366 let (dv, dt) = const_deref(cx, llconst, ty);
372 if adj.autoref.is_some() {
373 if adj.autoderefs == 0 {
374 // Don't copy data to do a deref+ref
375 // (i.e., skip the last auto-deref).
376 llconst = addr_of(cx, llconst, type_of::align_of(cx, ty), "autoref");
377 ty = cx.tcx().mk_imm_ref(cx.tcx().mk_region(ty::ReStatic), ty);
380 let (dv, dt) = const_deref(cx, llconst, ty);
383 // If we derefed a fat pointer then we will have an
384 // open type here. So we need to update the type with
385 // the one returned from const_deref.
389 if let Some(target) = adj.unsize {
390 let target = monomorphize::apply_param_substs(cx.tcx(),
394 let pointee_ty = ty.builtin_deref(true, ty::NoPreference)
395 .expect("consts: unsizing got non-pointer type").ty;
396 let (base, old_info) = if !type_is_sized(cx.tcx(), pointee_ty) {
397 // Normally, the source is a thin pointer and we are
398 // adding extra info to make a fat pointer. The exception
399 // is when we are upcasting an existing object fat pointer
400 // to use a different vtable. In that case, we want to
401 // load out the original data pointer so we can repackage
403 (const_get_elt(cx, llconst, &[abi::FAT_PTR_ADDR as u32]),
404 Some(const_get_elt(cx, llconst, &[abi::FAT_PTR_EXTRA as u32])))
409 let unsized_ty = target.builtin_deref(true, ty::NoPreference)
410 .expect("consts: unsizing got non-pointer target type").ty;
411 let ptr_ty = type_of::in_memory_type_of(cx, unsized_ty).ptr_to();
412 let base = ptrcast(base, ptr_ty);
413 let info = base::unsized_info(cx, pointee_ty, unsized_ty,
414 old_info, param_substs);
416 if old_info.is_none() {
417 let prev_const = cx.const_unsized().borrow_mut()
418 .insert(base, llconst);
419 assert!(prev_const.is_none() || prev_const == Some(llconst));
421 assert_eq!(abi::FAT_PTR_ADDR, 0);
422 assert_eq!(abi::FAT_PTR_EXTRA, 1);
423 llconst = C_struct(cx, &[base, info], false);
429 let llty = type_of::sizing_type_of(cx, ety_adjusted);
430 let csize = machine::llsize_of_alloc(cx, val_ty(llconst));
431 let tsize = machine::llsize_of_alloc(cx, llty);
433 cx.sess().abort_if_errors();
435 // FIXME these values could use some context
436 llvm::LLVMDumpValue(llconst);
437 llvm::LLVMDumpValue(C_undef(llty));
439 cx.sess().bug(&format!("const {:?} of type {:?} has size {} instead of {}",
443 Ok((llconst, ety_adjusted))
446 fn check_unary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
447 te: ValueRef, trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
448 // The only kind of unary expression that we check for validity
449 // here is `-expr`, to check if it "overflows" (e.g. `-i32::MIN`).
450 if let hir::ExprUnary(hir::UnNeg, ref inner_e) = e.node {
452 // An unfortunate special case: we parse e.g. -128 as a
453 // negation of the literal 128, which means if we're expecting
454 // a i8 (or if it was already suffixed, e.g. `-128_i8`), then
455 // 128 will have already overflowed to -128, and so then the
456 // constant evaluator thinks we're trying to negate -128.
458 // Catch this up front by looking for ExprLit directly,
459 // and just accepting it.
460 if let hir::ExprLit(_) = inner_e.node { return Ok(()); }
462 let result = match t.sty {
463 ty::TyInt(int_type) => {
464 let input = match const_to_opt_int(te) {
466 None => return Ok(()),
468 const_int_checked_neg(
469 input, e, Some(const_eval::IntTy::from(cx.tcx(), int_type)))
471 ty::TyUint(uint_type) => {
472 let input = match const_to_opt_uint(te) {
474 None => return Ok(()),
476 const_uint_checked_neg(
477 input, e, Some(const_eval::UintTy::from(cx.tcx(), uint_type)))
481 const_err(cx, e, result, trueconst)
487 fn const_err(cx: &CrateContext,
489 result: Result<ConstVal, ConstEvalErr>,
490 trueconst: TrueConst)
491 -> Result<(), ConstEvalFailure> {
492 match (result, trueconst) {
494 // We do not actually care about a successful result.
497 (Err(err), TrueConst::Yes) => {
498 cx.tcx().sess.span_err(e.span, &err.description());
499 Err(Compiletime(err))
501 (Err(err), TrueConst::No) => {
502 cx.tcx().sess.span_warn(e.span, &err.description());
508 fn check_binary_expr_validity(cx: &CrateContext, e: &hir::Expr, t: Ty,
509 te1: ValueRef, te2: ValueRef,
510 trueconst: TrueConst) -> Result<(), ConstEvalFailure> {
511 let b = if let hir::ExprBinary(b, _, _) = e.node { b } else { unreachable!() };
513 let result = match t.sty {
514 ty::TyInt(int_type) => {
515 let (lhs, rhs) = match (const_to_opt_int(te1),
516 const_to_opt_int(te2)) {
517 (Some(v1), Some(v2)) => (v1, v2),
521 let opt_ety = Some(const_eval::IntTy::from(cx.tcx(), int_type));
523 hir::BiAdd => const_int_checked_add(lhs, rhs, e, opt_ety),
524 hir::BiSub => const_int_checked_sub(lhs, rhs, e, opt_ety),
525 hir::BiMul => const_int_checked_mul(lhs, rhs, e, opt_ety),
526 hir::BiDiv => const_int_checked_div(lhs, rhs, e, opt_ety),
527 hir::BiRem => const_int_checked_rem(lhs, rhs, e, opt_ety),
528 hir::BiShl => const_int_checked_shl(lhs, rhs, e, opt_ety),
529 hir::BiShr => const_int_checked_shr(lhs, rhs, e, opt_ety),
533 ty::TyUint(uint_type) => {
534 let (lhs, rhs) = match (const_to_opt_uint(te1),
535 const_to_opt_uint(te2)) {
536 (Some(v1), Some(v2)) => (v1, v2),
540 let opt_ety = Some(const_eval::UintTy::from(cx.tcx(), uint_type));
542 hir::BiAdd => const_uint_checked_add(lhs, rhs, e, opt_ety),
543 hir::BiSub => const_uint_checked_sub(lhs, rhs, e, opt_ety),
544 hir::BiMul => const_uint_checked_mul(lhs, rhs, e, opt_ety),
545 hir::BiDiv => const_uint_checked_div(lhs, rhs, e, opt_ety),
546 hir::BiRem => const_uint_checked_rem(lhs, rhs, e, opt_ety),
547 hir::BiShl => const_uint_checked_shl(lhs, rhs, e, opt_ety),
548 hir::BiShr => const_uint_checked_shr(lhs, rhs, e, opt_ety),
554 const_err(cx, e, result, trueconst)
557 fn const_expr_unadjusted<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
560 param_substs: &'tcx Substs<'tcx>,
562 trueconst: TrueConst)
563 -> Result<ValueRef, ConstEvalFailure>
565 debug!("const_expr_unadjusted(e={:?}, ety={:?}, param_substs={:?})",
570 let map_list = |exprs: &[P<hir::Expr>]| -> Result<Vec<ValueRef>, ConstEvalFailure> {
572 .map(|e| const_expr(cx, &**e, param_substs, fn_args, trueconst).map(|(l, _)| l))
573 .collect::<Vec<Result<ValueRef, ConstEvalFailure>>>()
576 // this dance is necessary to eagerly run const_expr so all errors are reported
578 let _icx = push_ctxt("const_expr");
580 hir::ExprLit(ref lit) => const_lit(cx, e, &**lit),
581 hir::ExprBinary(b, ref e1, ref e2) => {
582 /* Neither type is bottom, and we expect them to be unified
583 * already, so the following is safe. */
584 let (te1, ty) = try!(const_expr(cx, &**e1, param_substs, fn_args, trueconst));
585 debug!("const_expr_unadjusted: te1={}, ty={:?}",
586 cx.tn().val_to_string(te1),
588 assert!(!ty.is_simd());
589 let is_float = ty.is_fp();
590 let signed = ty.is_signed();
592 let (te2, _) = try!(const_expr(cx, &**e2, param_substs, fn_args, trueconst));
594 try!(check_binary_expr_validity(cx, e, ty, te1, te2, trueconst));
596 unsafe { match b.node {
597 hir::BiAdd if is_float => llvm::LLVMConstFAdd(te1, te2),
598 hir::BiAdd => llvm::LLVMConstAdd(te1, te2),
600 hir::BiSub if is_float => llvm::LLVMConstFSub(te1, te2),
601 hir::BiSub => llvm::LLVMConstSub(te1, te2),
603 hir::BiMul if is_float => llvm::LLVMConstFMul(te1, te2),
604 hir::BiMul => llvm::LLVMConstMul(te1, te2),
606 hir::BiDiv if is_float => llvm::LLVMConstFDiv(te1, te2),
607 hir::BiDiv if signed => llvm::LLVMConstSDiv(te1, te2),
608 hir::BiDiv => llvm::LLVMConstUDiv(te1, te2),
610 hir::BiRem if is_float => llvm::LLVMConstFRem(te1, te2),
611 hir::BiRem if signed => llvm::LLVMConstSRem(te1, te2),
612 hir::BiRem => llvm::LLVMConstURem(te1, te2),
614 hir::BiAnd => llvm::LLVMConstAnd(te1, te2),
615 hir::BiOr => llvm::LLVMConstOr(te1, te2),
616 hir::BiBitXor => llvm::LLVMConstXor(te1, te2),
617 hir::BiBitAnd => llvm::LLVMConstAnd(te1, te2),
618 hir::BiBitOr => llvm::LLVMConstOr(te1, te2),
620 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
621 llvm::LLVMConstShl(te1, te2)
624 let te2 = base::cast_shift_const_rhs(b.node, te1, te2);
625 if signed { llvm::LLVMConstAShr(te1, te2) }
626 else { llvm::LLVMConstLShr(te1, te2) }
628 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiLe | hir::BiGt | hir::BiGe => {
630 let cmp = base::bin_op_to_fcmp_predicate(cx, b.node);
631 ConstFCmp(cmp, te1, te2)
633 let cmp = base::bin_op_to_icmp_predicate(cx, b.node, signed);
634 ConstICmp(cmp, te1, te2)
637 } } // unsafe { match b.node {
639 hir::ExprUnary(u, ref inner_e) => {
640 let (te, ty) = try!(const_expr(cx, &**inner_e, param_substs, fn_args, trueconst));
642 try!(check_unary_expr_validity(cx, e, ty, te, trueconst));
644 let is_float = ty.is_fp();
646 hir::UnDeref => const_deref(cx, te, ty).0,
647 hir::UnNot => llvm::LLVMConstNot(te),
648 hir::UnNeg if is_float => llvm::LLVMConstFNeg(te),
649 hir::UnNeg => llvm::LLVMConstNeg(te),
652 hir::ExprField(ref base, field) => {
653 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
654 let brepr = adt::represent_type(cx, bt);
655 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
656 let ix = vinfo.field_index(field.node);
657 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, ix)
659 hir::ExprTupField(ref base, idx) => {
660 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
661 let brepr = adt::represent_type(cx, bt);
662 let vinfo = VariantInfo::from_ty(cx.tcx(), bt, None);
663 adt::const_get_field(cx, &*brepr, bv, vinfo.discr, idx.node)
665 hir::ExprIndex(ref base, ref index) => {
666 let (bv, bt) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
667 let iv = match eval_const_expr_partial(cx.tcx(), &index, ExprTypeChecked, None) {
668 Ok(ConstVal::Int(i)) => i as u64,
669 Ok(ConstVal::Uint(u)) => u,
670 _ => cx.sess().span_bug(index.span,
671 "index is not an integer-constant expression")
673 let (arr, len) = match bt.sty {
674 ty::TyArray(_, u) => (bv, C_uint(cx, u)),
675 ty::TySlice(_) | ty::TyStr => {
676 let e1 = const_get_elt(cx, bv, &[0]);
677 (const_deref_ptr(cx, e1), const_get_elt(cx, bv, &[1]))
679 ty::TyRef(_, mt) => match mt.ty.sty {
680 ty::TyArray(_, u) => {
681 (const_deref_ptr(cx, bv), C_uint(cx, u))
683 _ => cx.sess().span_bug(base.span,
684 &format!("index-expr base must be a vector \
685 or string type, found {:?}",
688 _ => cx.sess().span_bug(base.span,
689 &format!("index-expr base must be a vector \
690 or string type, found {:?}",
694 let len = unsafe { llvm::LLVMConstIntGetZExtValue(len) as u64 };
695 let len = match bt.sty {
696 ty::TyBox(ty) | ty::TyRef(_, ty::TypeAndMut{ty, ..}) => match ty.sty {
706 // FIXME #3170: report this earlier on in the const-eval
707 // pass. Reporting here is a bit late.
708 span_err!(cx.sess(), e.span, E0515,
709 "const index-expr is out of bounds");
710 C_undef(val_ty(arr).element_type())
712 const_get_elt(cx, arr, &[iv as c_uint])
715 hir::ExprCast(ref base, _) => {
717 let llty = type_of::type_of(cx, t_cast);
718 let (v, t_expr) = try!(const_expr(cx, &**base, param_substs, fn_args, trueconst));
719 debug!("trans_const_cast({:?} as {:?})", t_expr, t_cast);
720 if expr::cast_is_noop(cx.tcx(), base, t_expr, t_cast) {
723 if type_is_fat_ptr(cx.tcx(), t_expr) {
724 // Fat pointer casts.
726 t_cast.builtin_deref(true, ty::NoPreference).expect("cast to non-pointer").ty;
727 let ptr_ty = type_of::in_memory_type_of(cx, t_cast_inner).ptr_to();
728 let addr = ptrcast(const_get_elt(cx, v, &[abi::FAT_PTR_ADDR as u32]),
730 if type_is_fat_ptr(cx.tcx(), t_cast) {
731 let info = const_get_elt(cx, v, &[abi::FAT_PTR_EXTRA as u32]);
732 return Ok(C_struct(cx, &[addr, info], false))
738 CastTy::from_ty(t_expr).expect("bad input type for cast"),
739 CastTy::from_ty(t_cast).expect("bad output type for cast"),
741 (CastTy::Int(IntTy::CEnum), CastTy::Int(_)) => {
742 let repr = adt::represent_type(cx, t_expr);
743 let discr = adt::const_get_discrim(cx, &*repr, v);
744 let iv = C_integral(cx.int_type(), discr.0, false);
745 let s = adt::is_discr_signed(&*repr) as Bool;
746 llvm::LLVMConstIntCast(iv, llty.to_ref(), s)
748 (CastTy::Int(_), CastTy::Int(_)) => {
749 let s = t_expr.is_signed() as Bool;
750 llvm::LLVMConstIntCast(v, llty.to_ref(), s)
752 (CastTy::Int(_), CastTy::Float) => {
753 if t_expr.is_signed() {
754 llvm::LLVMConstSIToFP(v, llty.to_ref())
756 llvm::LLVMConstUIToFP(v, llty.to_ref())
759 (CastTy::Float, CastTy::Float) => llvm::LLVMConstFPCast(v, llty.to_ref()),
760 (CastTy::Float, CastTy::Int(IntTy::I)) => llvm::LLVMConstFPToSI(v, llty.to_ref()),
761 (CastTy::Float, CastTy::Int(_)) => llvm::LLVMConstFPToUI(v, llty.to_ref()),
762 (CastTy::Ptr(_), CastTy::Ptr(_)) | (CastTy::FnPtr, CastTy::Ptr(_))
763 | (CastTy::RPtr(_), CastTy::Ptr(_)) => {
766 (CastTy::FnPtr, CastTy::FnPtr) => ptrcast(v, llty), // isn't this a coercion?
767 (CastTy::Int(_), CastTy::Ptr(_)) => llvm::LLVMConstIntToPtr(v, llty.to_ref()),
768 (CastTy::Ptr(_), CastTy::Int(_)) | (CastTy::FnPtr, CastTy::Int(_)) => {
769 llvm::LLVMConstPtrToInt(v, llty.to_ref())
772 cx.sess().impossible_case(e.span,
773 "bad combination of types for cast")
775 } } // unsafe { match ( ... ) {
777 hir::ExprAddrOf(hir::MutImmutable, ref sub) => {
778 // If this is the address of some static, then we need to return
779 // the actual address of the static itself (short circuit the rest
784 hir::ExprBlock(ref blk) => {
785 if let Some(ref sub) = blk.expr {
794 let opt_def = cx.tcx().def_map.borrow().get(&cur.id).map(|d| d.full_def());
795 if let Some(Def::Static(def_id, _)) = opt_def {
796 common::get_static_val(cx, def_id, ety)
798 // If this isn't the address of a static, then keep going through
799 // normal constant evaluation.
800 let (v, ty) = try!(const_expr(cx, &**sub, param_substs, fn_args, trueconst));
801 addr_of(cx, v, type_of::align_of(cx, ty), "ref")
804 hir::ExprAddrOf(hir::MutMutable, ref sub) => {
805 let (v, ty) = try!(const_expr(cx, &**sub, param_substs, fn_args, trueconst));
806 addr_of_mut(cx, v, type_of::align_of(cx, ty), "ref_mut_slice")
808 hir::ExprTup(ref es) => {
809 let repr = adt::represent_type(cx, ety);
810 let vals = try!(map_list(&es[..]));
811 adt::trans_const(cx, &*repr, Disr(0), &vals[..])
813 hir::ExprStruct(_, ref fs, ref base_opt) => {
814 let repr = adt::represent_type(cx, ety);
816 let base_val = match *base_opt {
817 Some(ref base) => Some(try!(const_expr(
827 let VariantInfo { discr, fields } = VariantInfo::of_node(cx.tcx(), ety, e.id);
828 let cs = fields.iter().enumerate().map(|(ix, &Field(f_name, _))| {
829 match (fs.iter().find(|f| f_name == f.name.node), base_val) {
830 (Some(ref f), _) => {
831 const_expr(cx, &*f.expr, param_substs, fn_args, trueconst).map(|(l, _)| l)
833 (_, Some((bv, _))) => Ok(adt::const_get_field(cx, &*repr, bv, discr, ix)),
834 (_, None) => cx.sess().span_bug(e.span, "missing struct field"),
837 .collect::<Vec<Result<_, ConstEvalFailure>>>()
839 .collect::<Result<Vec<_>,ConstEvalFailure>>();
844 adt::trans_const(cx, &*repr, discr, &cs[..])
847 hir::ExprVec(ref es) => {
848 let unit_ty = ety.sequence_element_type(cx.tcx());
849 let llunitty = type_of::type_of(cx, unit_ty);
858 .collect::<Vec<Result<_, ConstEvalFailure>>>()
860 .collect::<Result<Vec<_>, ConstEvalFailure>>();
862 // If the vector contains enums, an LLVM array won't work.
863 if vs.iter().any(|vi| val_ty(*vi) != llunitty) {
864 C_struct(cx, &vs[..], false)
866 C_array(llunitty, &vs[..])
869 hir::ExprRepeat(ref elem, ref count) => {
870 let unit_ty = ety.sequence_element_type(cx.tcx());
871 let llunitty = type_of::type_of(cx, unit_ty);
872 let n = cx.tcx().eval_repeat_count(count);
873 let unit_val = try!(const_expr(cx, &**elem, param_substs, fn_args, trueconst)).0;
874 let vs = vec![unit_val; n];
875 if val_ty(unit_val) != llunitty {
876 C_struct(cx, &vs[..], false)
878 C_array(llunitty, &vs[..])
881 hir::ExprPath(..) => {
882 let def = cx.tcx().def_map.borrow().get(&e.id).unwrap().full_def();
884 Def::Local(_, id) => {
885 if let Some(val) = fn_args.and_then(|args| args.get(&id).cloned()) {
888 cx.sess().span_bug(e.span, "const fn argument not found")
891 Def::Fn(..) | Def::Method(..) => {
892 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
894 Def::Const(def_id) | Def::AssociatedConst(def_id) => {
895 const_deref_ptr(cx, try!(get_const_val(cx, def_id, e, param_substs)))
897 Def::Variant(enum_did, variant_did) => {
898 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
900 ty::VariantKind::Unit => {
901 let repr = adt::represent_type(cx, ety);
902 adt::trans_const(cx, &*repr, Disr::from(vinfo.disr_val), &[])
904 ty::VariantKind::Tuple => {
905 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
907 ty::VariantKind::Struct => {
908 cx.sess().span_bug(e.span, "path-expr refers to a dict variant!")
913 if let ty::TyBareFn(..) = ety.sty {
915 expr::trans_def_fn_unadjusted(cx, e, def, param_substs).val
918 C_null(type_of::type_of(cx, ety))
922 cx.sess().span_bug(e.span, "expected a const, fn, struct, \
927 hir::ExprCall(ref callee, ref args) => {
928 let mut callee = &**callee;
930 callee = match callee.node {
931 hir::ExprBlock(ref block) => match block.expr {
932 Some(ref tail) => &**tail,
938 let def = cx.tcx().def_map.borrow()[&callee.id].full_def();
939 let arg_vals = try!(map_list(args));
941 Def::Fn(did) | Def::Method(did) => {
953 C_vector(&arg_vals[..])
955 let repr = adt::represent_type(cx, ety);
956 adt::trans_const(cx, &*repr, Disr(0), &arg_vals[..])
959 Def::Variant(enum_did, variant_did) => {
960 let repr = adt::represent_type(cx, ety);
961 let vinfo = cx.tcx().lookup_adt_def(enum_did).variant_with_id(variant_did);
964 Disr::from(vinfo.disr_val),
967 _ => cx.sess().span_bug(e.span, "expected a struct, variant, or const fn def"),
970 hir::ExprMethodCall(_, _, ref args) => {
971 let arg_vals = try!(map_list(args));
972 let method_call = ty::MethodCall::expr(e.id);
973 let method_did = cx.tcx().tables.borrow().method_map[&method_call].def_id;
974 try!(const_fn_call(cx, MethodCallKey(method_call),
975 method_did, &arg_vals, param_substs, trueconst))
977 hir::ExprType(ref e, _) => try!(const_expr(cx, &**e, param_substs, fn_args, trueconst)).0,
978 hir::ExprBlock(ref block) => {
980 Some(ref expr) => try!(const_expr(
990 hir::ExprClosure(_, ref decl, ref body) => {
992 ty::TyClosure(def_id, ref substs) => {
993 closure::trans_closure_expr(closure::Dest::Ignore(cx),
1004 &format!("bad type for closure expr: {:?}", ety))
1006 C_null(type_of::type_of(cx, ety))
1008 _ => cx.sess().span_bug(e.span,
1009 "bad constant expression type in consts::const_expr"),
1013 pub fn trans_static(ccx: &CrateContext,
1017 attrs: &[ast::Attribute])
1018 -> Result<ValueRef, ConstEvalErr> {
1020 let _icx = push_ctxt("trans_static");
1021 let g = base::get_item_val(ccx, id);
1023 let empty_substs = ccx.tcx().mk_substs(Substs::trans_empty());
1024 let (v, _) = try!(const_expr(
1030 ).map_err(|e| e.into_inner()));
1032 // boolean SSA values are i1, but they have to be stored in i8 slots,
1033 // otherwise some LLVM optimization passes don't work as expected
1034 let mut val_llty = llvm::LLVMTypeOf(v);
1035 let v = if val_llty == Type::i1(ccx).to_ref() {
1036 val_llty = Type::i8(ccx).to_ref();
1037 llvm::LLVMConstZExt(v, val_llty)
1042 let ty = ccx.tcx().node_id_to_type(id);
1043 let llty = type_of::type_of(ccx, ty);
1044 let g = if val_llty == llty.to_ref() {
1047 // If we created the global with the wrong type,
1048 // correct the type.
1049 let empty_string = CString::new("").unwrap();
1050 let name_str_ref = CStr::from_ptr(llvm::LLVMGetValueName(g));
1051 let name_string = CString::new(name_str_ref.to_bytes()).unwrap();
1052 llvm::LLVMSetValueName(g, empty_string.as_ptr());
1053 let new_g = llvm::LLVMGetOrInsertGlobal(
1054 ccx.llmod(), name_string.as_ptr(), val_llty);
1055 // To avoid breaking any invariants, we leave around the old
1056 // global for the moment; we'll replace all references to it
1057 // with the new global later. (See base::trans_crate.)
1058 ccx.statics_to_rauw().borrow_mut().push((g, new_g));
1061 llvm::LLVMSetAlignment(g, type_of::align_of(ccx, ty));
1062 llvm::LLVMSetInitializer(g, v);
1064 // As an optimization, all shared statics which do not have interior
1065 // mutability are placed into read-only memory.
1066 if m != hir::MutMutable {
1067 let tcontents = ty.type_contents(ccx.tcx());
1068 if !tcontents.interior_unsafe() {
1069 llvm::LLVMSetGlobalConstant(g, llvm::True);
1073 debuginfo::create_global_var_metadata(ccx, id, g);
1075 if attr::contains_name(attrs,
1077 llvm::set_thread_local(g, true);