1 // Copyright 2012-2014 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.
11 //! # Translation of Expressions
13 //! The expr module handles translation of expressions. The most general
14 //! translation routine is `trans()`, which will translate an expression
15 //! into a datum. `trans_into()` is also available, which will translate
16 //! an expression and write the result directly into memory, sometimes
17 //! avoiding the need for a temporary stack slot. Finally,
18 //! `trans_to_lvalue()` is available if you'd like to ensure that the
19 //! result has cleanup scheduled.
21 //! Internally, each of these functions dispatches to various other
22 //! expression functions depending on the kind of expression. We divide
23 //! up expressions into:
25 //! - **Datum expressions:** Those that most naturally yield values.
26 //! Examples would be `22`, `box x`, or `a + b` (when not overloaded).
27 //! - **DPS expressions:** Those that most naturally write into a location
28 //! in memory. Examples would be `foo()` or `Point { x: 3, y: 4 }`.
29 //! - **Statement expressions:** That that do not generate a meaningful
30 //! result. Examples would be `while { ... }` or `return 44`.
32 //! Public entry points:
34 //! - `trans_into(bcx, expr, dest) -> bcx`: evaluates an expression,
35 //! storing the result into `dest`. This is the preferred form, if you
38 //! - `trans(bcx, expr) -> DatumBlock`: evaluates an expression, yielding
39 //! `Datum` with the result. You can then store the datum, inspect
40 //! the value, etc. This may introduce temporaries if the datum is a
43 //! - `trans_to_lvalue(bcx, expr, "...") -> DatumBlock`: evaluates an
44 //! expression and ensures that the result has a cleanup associated with it,
45 //! creating a temporary stack slot if necessary.
47 //! - `trans_local_var -> Datum`: looks up a local variable or upvar.
49 #![allow(non_camel_case_types)]
51 pub use self::Dest::*;
52 use self::lazy_binop_ty::*;
55 use llvm::{self, ValueRef, TypeKind};
56 use middle::const_qualif::ConstQualif;
58 use middle::subst::Substs;
59 use trans::{_match, adt, asm, base, closure, consts, controlflow};
62 use trans::callee::{Callee, ArgExprs, ArgOverloadedCall, ArgOverloadedOp};
63 use trans::cleanup::{self, CleanupMethods, DropHintMethods};
66 use trans::debuginfo::{self, DebugLoc, ToDebugLoc};
73 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
74 use middle::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer};
75 use middle::ty::adjustment::CustomCoerceUnsized;
76 use middle::ty::{self, Ty, TyCtxt};
77 use middle::ty::MethodCall;
78 use middle::ty::cast::{CastKind, CastTy};
79 use util::common::indenter;
80 use trans::machine::{llsize_of, llsize_of_alloc};
81 use trans::type_::Type;
86 use syntax::{ast, codemap};
87 use syntax::parse::token::InternedString;
92 // These are passed around by the code generating functions to track the
93 // destination of a computation's value.
95 #[derive(Copy, Clone, PartialEq)]
102 pub fn to_string(&self, ccx: &CrateContext) -> String {
104 SaveIn(v) => format!("SaveIn({})", ccx.tn().val_to_string(v)),
105 Ignore => "Ignore".to_string()
110 /// This function is equivalent to `trans(bcx, expr).store_to_dest(dest)` but it may generate
111 /// better optimized LLVM code.
112 pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
115 -> Block<'blk, 'tcx> {
118 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
120 if adjustment_required(bcx, expr) {
121 // use trans, which may be less efficient but
122 // which will perform the adjustments:
123 let datum = unpack_datum!(bcx, trans(bcx, expr));
124 return datum.store_to_dest(bcx, dest, expr.id);
127 let qualif = *bcx.tcx().const_qualif_map.borrow().get(&expr.id).unwrap();
128 if !qualif.intersects(ConstQualif::NOT_CONST | ConstQualif::NEEDS_DROP) {
129 if !qualif.intersects(ConstQualif::PREFER_IN_PLACE) {
130 if let SaveIn(lldest) = dest {
131 match consts::get_const_expr_as_global(bcx.ccx(), expr, qualif,
132 bcx.fcx.param_substs,
133 consts::TrueConst::No) {
135 // Cast pointer to destination, because constants
136 // have different types.
137 let lldest = PointerCast(bcx, lldest, val_ty(global));
138 memcpy_ty(bcx, lldest, global, expr_ty_adjusted(bcx, expr));
141 Err(consts::ConstEvalFailure::Runtime(_)) => {
142 // in case const evaluation errors, translate normally
143 // debug assertions catch the same errors
146 Err(consts::ConstEvalFailure::Compiletime(_)) => {
152 // If we see a const here, that's because it evaluates to a type with zero size. We
153 // should be able to just discard it, since const expressions are guaranteed not to
154 // have side effects. This seems to be reached through tuple struct constructors being
155 // passed zero-size constants.
156 if let hir::ExprPath(..) = expr.node {
157 match bcx.def(expr.id) {
158 Def::Const(_) | Def::AssociatedConst(_) => {
159 assert!(type_is_zero_size(bcx.ccx(), bcx.tcx().node_id_to_type(expr.id)));
166 // Even if we don't have a value to emit, and the expression
167 // doesn't have any side-effects, we still have to translate the
168 // body of any closures.
169 // FIXME: Find a better way of handling this case.
171 // The only way we're going to see a `const` at this point is if
172 // it prefers in-place instantiation, likely because it contains
173 // `[x; N]` somewhere within.
175 hir::ExprPath(..) => {
176 match bcx.def(expr.id) {
177 Def::Const(did) | Def::AssociatedConst(did) => {
178 let empty_substs = bcx.tcx().mk_substs(Substs::trans_empty());
179 let const_expr = consts::get_const_expr(bcx.ccx(), did, expr,
181 // Temporarily get cleanup scopes out of the way,
182 // as they require sub-expressions to be contained
183 // inside the current AST scope.
184 // These should record no cleanups anyways, `const`
185 // can't have destructors.
186 let scopes = mem::replace(&mut *bcx.fcx.scopes.borrow_mut(),
188 // Lock emitted debug locations to the location of
189 // the constant reference expression.
190 debuginfo::with_source_location_override(bcx.fcx,
193 bcx = trans_into(bcx, const_expr, dest)
195 let scopes = mem::replace(&mut *bcx.fcx.scopes.borrow_mut(),
197 assert!(scopes.is_empty());
208 debug!("trans_into() expr={:?}", expr);
210 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
214 bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
216 let kind = expr_kind(bcx.tcx(), expr);
218 ExprKind::Lvalue | ExprKind::RvalueDatum => {
219 trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
221 ExprKind::RvalueDps => {
222 trans_rvalue_dps_unadjusted(bcx, expr, dest)
224 ExprKind::RvalueStmt => {
225 trans_rvalue_stmt_unadjusted(bcx, expr)
229 bcx.fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id)
232 /// Translates an expression, returning a datum (and new block) encapsulating the result. When
233 /// possible, it is preferred to use `trans_into`, as that may avoid creating a temporary on the
235 pub fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
237 -> DatumBlock<'blk, 'tcx, Expr> {
238 debug!("trans(expr={:?})", expr);
242 let qualif = *bcx.tcx().const_qualif_map.borrow().get(&expr.id).unwrap();
243 let adjusted_global = !qualif.intersects(ConstQualif::NON_STATIC_BORROWS);
244 let global = if !qualif.intersects(ConstQualif::NOT_CONST | ConstQualif::NEEDS_DROP) {
245 match consts::get_const_expr_as_global(bcx.ccx(), expr, qualif,
246 bcx.fcx.param_substs,
247 consts::TrueConst::No) {
249 if qualif.intersects(ConstQualif::HAS_STATIC_BORROWS) {
250 // Is borrowed as 'static, must return lvalue.
252 // Cast pointer to global, because constants have different types.
253 let const_ty = expr_ty_adjusted(bcx, expr);
254 let llty = type_of::type_of(bcx.ccx(), const_ty);
255 let global = PointerCast(bcx, global, llty.ptr_to());
256 let datum = Datum::new(global, const_ty, Lvalue::new("expr::trans"));
257 return DatumBlock::new(bcx, datum.to_expr_datum());
260 // Otherwise, keep around and perform adjustments, if needed.
261 let const_ty = if adjusted_global {
262 expr_ty_adjusted(bcx, expr)
267 // This could use a better heuristic.
268 Some(if type_is_immediate(bcx.ccx(), const_ty) {
269 // Cast pointer to global, because constants have different types.
270 let llty = type_of::type_of(bcx.ccx(), const_ty);
271 let global = PointerCast(bcx, global, llty.ptr_to());
272 // Maybe just get the value directly, instead of loading it?
273 immediate_rvalue(load_ty(bcx, global, const_ty), const_ty)
275 let scratch = alloc_ty(bcx, const_ty, "const");
276 call_lifetime_start(bcx, scratch);
277 let lldest = if !const_ty.is_structural() {
278 // Cast pointer to slot, because constants have different types.
279 PointerCast(bcx, scratch, val_ty(global))
281 // In this case, memcpy_ty calls llvm.memcpy after casting both
282 // source and destination to i8*, so we don't need any casts.
285 memcpy_ty(bcx, lldest, global, const_ty);
286 Datum::new(scratch, const_ty, Rvalue::new(ByRef))
289 Err(consts::ConstEvalFailure::Runtime(_)) => {
290 // in case const evaluation errors, translate normally
291 // debug assertions catch the same errors
295 Err(consts::ConstEvalFailure::Compiletime(_)) => {
296 // generate a dummy llvm value
297 let const_ty = expr_ty(bcx, expr);
298 let llty = type_of::type_of(bcx.ccx(), const_ty);
299 let dummy = C_undef(llty.ptr_to());
300 Some(Datum::new(dummy, const_ty, Rvalue::new(ByRef)))
307 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
311 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
312 let datum = match global {
313 Some(rvalue) => rvalue.to_expr_datum(),
314 None => unpack_datum!(bcx, trans_unadjusted(bcx, expr))
316 let datum = if adjusted_global {
317 datum // trans::consts already performed adjustments.
319 unpack_datum!(bcx, apply_adjustments(bcx, expr, datum))
321 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id);
322 return DatumBlock::new(bcx, datum);
325 pub fn get_meta(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
326 StructGEP(bcx, fat_ptr, abi::FAT_PTR_EXTRA)
329 pub fn get_dataptr(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
330 StructGEP(bcx, fat_ptr, abi::FAT_PTR_ADDR)
333 pub fn copy_fat_ptr(bcx: Block, src_ptr: ValueRef, dst_ptr: ValueRef) {
334 Store(bcx, Load(bcx, get_dataptr(bcx, src_ptr)), get_dataptr(bcx, dst_ptr));
335 Store(bcx, Load(bcx, get_meta(bcx, src_ptr)), get_meta(bcx, dst_ptr));
338 fn adjustment_required<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
339 expr: &hir::Expr) -> bool {
340 let adjustment = match bcx.tcx().tables.borrow().adjustments.get(&expr.id).cloned() {
341 None => { return false; }
345 // Don't skip a conversion from Box<T> to &T, etc.
346 if bcx.tcx().is_overloaded_autoderef(expr.id, 0) {
351 AdjustReifyFnPointer => true,
352 AdjustUnsafeFnPointer | AdjustMutToConstPointer => {
353 // purely a type-level thing
356 AdjustDerefRef(ref adj) => {
357 // We are a bit paranoid about adjustments and thus might have a re-
358 // borrow here which merely derefs and then refs again (it might have
359 // a different region or mutability, but we don't care here).
360 !(adj.autoderefs == 1 && adj.autoref.is_some() && adj.unsize.is_none())
365 /// Helper for trans that apply adjustments from `expr` to `datum`, which should be the unadjusted
366 /// translation of `expr`.
367 fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
369 datum: Datum<'tcx, Expr>)
370 -> DatumBlock<'blk, 'tcx, Expr>
373 let mut datum = datum;
374 let adjustment = match bcx.tcx().tables.borrow().adjustments.get(&expr.id).cloned() {
376 return DatumBlock::new(bcx, datum);
380 debug!("unadjusted datum for expr {:?}: {} adjustment={:?}",
382 datum.to_string(bcx.ccx()),
385 AdjustReifyFnPointer => {
387 ty::TyFnDef(def_id, substs, _) => {
388 datum = Callee::def(bcx.ccx(), def_id, substs, datum.ty)
389 .reify(bcx.ccx()).to_expr_datum();
392 unreachable!("{} cannot be reified to a fn ptr", datum.ty)
396 AdjustUnsafeFnPointer | AdjustMutToConstPointer => {
397 // purely a type-level thing
399 AdjustDerefRef(ref adj) => {
400 let skip_reborrows = if adj.autoderefs == 1 && adj.autoref.is_some() {
401 // We are a bit paranoid about adjustments and thus might have a re-
402 // borrow here which merely derefs and then refs again (it might have
403 // a different region or mutability, but we don't care here).
405 // Don't skip a conversion from Box<T> to &T, etc.
407 if bcx.tcx().is_overloaded_autoderef(expr.id, 0) {
408 // Don't skip an overloaded deref.
420 if adj.autoderefs > skip_reborrows {
422 let lval = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "auto_deref", expr.id));
423 datum = unpack_datum!(bcx, deref_multiple(bcx, expr,
424 lval.to_expr_datum(),
425 adj.autoderefs - skip_reborrows));
428 // (You might think there is a more elegant way to do this than a
429 // skip_reborrows bool, but then you remember that the borrow checker exists).
430 if skip_reborrows == 0 && adj.autoref.is_some() {
431 datum = unpack_datum!(bcx, auto_ref(bcx, datum, expr));
434 if let Some(target) = adj.unsize {
435 // We do not arrange cleanup ourselves; if we already are an
436 // L-value, then cleanup will have already been scheduled (and
437 // the `datum.to_rvalue_datum` call below will emit code to zero
438 // the drop flag when moving out of the L-value). If we are an
439 // R-value, then we do not need to schedule cleanup.
440 let source_datum = unpack_datum!(bcx,
441 datum.to_rvalue_datum(bcx, "__coerce_source"));
443 let target = bcx.monomorphize(&target);
445 let scratch = alloc_ty(bcx, target, "__coerce_target");
446 call_lifetime_start(bcx, scratch);
447 let target_datum = Datum::new(scratch, target,
449 bcx = coerce_unsized(bcx, expr.span, source_datum, target_datum);
450 datum = Datum::new(scratch, target,
451 RvalueExpr(Rvalue::new(ByRef)));
455 debug!("after adjustments, datum={}", datum.to_string(bcx.ccx()));
456 DatumBlock::new(bcx, datum)
459 fn coerce_unsized<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
461 source: Datum<'tcx, Rvalue>,
462 target: Datum<'tcx, Rvalue>)
463 -> Block<'blk, 'tcx> {
465 debug!("coerce_unsized({} -> {})",
466 source.to_string(bcx.ccx()),
467 target.to_string(bcx.ccx()));
469 match (&source.ty.sty, &target.ty.sty) {
470 (&ty::TyBox(a), &ty::TyBox(b)) |
471 (&ty::TyRef(_, ty::TypeAndMut { ty: a, .. }),
472 &ty::TyRef(_, ty::TypeAndMut { ty: b, .. })) |
473 (&ty::TyRef(_, ty::TypeAndMut { ty: a, .. }),
474 &ty::TyRawPtr(ty::TypeAndMut { ty: b, .. })) |
475 (&ty::TyRawPtr(ty::TypeAndMut { ty: a, .. }),
476 &ty::TyRawPtr(ty::TypeAndMut { ty: b, .. })) => {
477 let (inner_source, inner_target) = (a, b);
479 let (base, old_info) = if !type_is_sized(bcx.tcx(), inner_source) {
480 // Normally, the source is a thin pointer and we are
481 // adding extra info to make a fat pointer. The exception
482 // is when we are upcasting an existing object fat pointer
483 // to use a different vtable. In that case, we want to
484 // load out the original data pointer so we can repackage
486 (Load(bcx, get_dataptr(bcx, source.val)),
487 Some(Load(bcx, get_meta(bcx, source.val))))
489 let val = if source.kind.is_by_ref() {
490 load_ty(bcx, source.val, source.ty)
497 let info = unsized_info(bcx.ccx(), inner_source, inner_target, old_info);
499 // Compute the base pointer. This doesn't change the pointer value,
500 // but merely its type.
501 let ptr_ty = type_of::in_memory_type_of(bcx.ccx(), inner_target).ptr_to();
502 let base = PointerCast(bcx, base, ptr_ty);
504 Store(bcx, base, get_dataptr(bcx, target.val));
505 Store(bcx, info, get_meta(bcx, target.val));
508 // This can be extended to enums and tuples in the future.
509 // (&ty::TyEnum(def_id_a, _), &ty::TyEnum(def_id_b, _)) |
510 (&ty::TyStruct(def_id_a, _), &ty::TyStruct(def_id_b, _)) => {
511 assert_eq!(def_id_a, def_id_b);
513 // The target is already by-ref because it's to be written to.
514 let source = unpack_datum!(bcx, source.to_ref_datum(bcx));
515 assert!(target.kind.is_by_ref());
517 let kind = custom_coerce_unsize_info(bcx.ccx(), source.ty, target.ty);
519 let repr_source = adt::represent_type(bcx.ccx(), source.ty);
520 let src_fields = match &*repr_source {
521 &adt::Repr::Univariant(ref s, _) => &s.fields,
522 _ => bcx.sess().span_bug(span,
523 &format!("Non univariant struct? (repr_source: {:?})",
526 let repr_target = adt::represent_type(bcx.ccx(), target.ty);
527 let target_fields = match &*repr_target {
528 &adt::Repr::Univariant(ref s, _) => &s.fields,
529 _ => bcx.sess().span_bug(span,
530 &format!("Non univariant struct? (repr_target: {:?})",
534 let coerce_index = match kind {
535 CustomCoerceUnsized::Struct(i) => i
537 assert!(coerce_index < src_fields.len() && src_fields.len() == target_fields.len());
539 let source_val = adt::MaybeSizedValue::sized(source.val);
540 let target_val = adt::MaybeSizedValue::sized(target.val);
542 let iter = src_fields.iter().zip(target_fields).enumerate();
543 for (i, (src_ty, target_ty)) in iter {
544 let ll_source = adt::trans_field_ptr(bcx, &repr_source, source_val, Disr(0), i);
545 let ll_target = adt::trans_field_ptr(bcx, &repr_target, target_val, Disr(0), i);
547 // If this is the field we need to coerce, recurse on it.
548 if i == coerce_index {
549 coerce_unsized(bcx, span,
550 Datum::new(ll_source, src_ty,
552 Datum::new(ll_target, target_ty,
553 Rvalue::new(ByRef)));
555 // Otherwise, simply copy the data from the source.
556 assert!(src_ty.is_phantom_data() || src_ty == target_ty);
557 memcpy_ty(bcx, ll_target, ll_source, src_ty);
561 _ => bcx.sess().bug(&format!("coerce_unsized: invalid coercion {:?} -> {:?}",
568 /// Translates an expression in "lvalue" mode -- meaning that it returns a reference to the memory
569 /// that the expr represents.
571 /// If this expression is an rvalue, this implies introducing a temporary. In other words,
572 /// something like `x().f` is translated into roughly the equivalent of
574 /// { tmp = x(); tmp.f }
575 pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
578 -> DatumBlock<'blk, 'tcx, Lvalue> {
580 let datum = unpack_datum!(bcx, trans(bcx, expr));
581 return datum.to_lvalue_datum(bcx, name, expr.id);
584 /// A version of `trans` that ignores adjustments. You almost certainly do not want to call this
586 fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
588 -> DatumBlock<'blk, 'tcx, Expr> {
591 debug!("trans_unadjusted(expr={:?})", expr);
592 let _indenter = indenter();
594 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
596 return match expr_kind(bcx.tcx(), expr) {
597 ExprKind::Lvalue | ExprKind::RvalueDatum => {
598 let datum = unpack_datum!(bcx, {
599 trans_datum_unadjusted(bcx, expr)
602 DatumBlock {bcx: bcx, datum: datum}
605 ExprKind::RvalueStmt => {
606 bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
607 nil(bcx, expr_ty(bcx, expr))
610 ExprKind::RvalueDps => {
611 let ty = expr_ty(bcx, expr);
612 if type_is_zero_size(bcx.ccx(), ty) {
613 bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
616 let scratch = rvalue_scratch_datum(bcx, ty, "");
617 bcx = trans_rvalue_dps_unadjusted(
618 bcx, expr, SaveIn(scratch.val));
620 // Note: this is not obviously a good idea. It causes
621 // immediate values to be loaded immediately after a
622 // return from a call or other similar expression,
623 // which in turn leads to alloca's having shorter
624 // lifetimes and hence larger stack frames. However,
625 // in turn it can lead to more register pressure.
626 // Still, in practice it seems to increase
627 // performance, since we have fewer problems with
629 let scratch = unpack_datum!(
630 bcx, scratch.to_appropriate_datum(bcx));
632 DatumBlock::new(bcx, scratch.to_expr_datum())
637 fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: Ty<'tcx>)
638 -> DatumBlock<'blk, 'tcx, Expr> {
639 let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
640 let datum = immediate_rvalue(llval, ty);
641 DatumBlock::new(bcx, datum.to_expr_datum())
645 fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
647 -> DatumBlock<'blk, 'tcx, Expr> {
650 let _icx = push_ctxt("trans_datum_unadjusted");
653 hir::ExprType(ref e, _) => {
656 hir::ExprPath(..) => {
657 trans_def(bcx, expr, bcx.def(expr.id))
659 hir::ExprField(ref base, name) => {
660 trans_rec_field(bcx, &base, name.node)
662 hir::ExprTupField(ref base, idx) => {
663 trans_rec_tup_field(bcx, &base, idx.node)
665 hir::ExprIndex(ref base, ref idx) => {
666 trans_index(bcx, expr, &base, &idx, MethodCall::expr(expr.id))
668 hir::ExprBox(ref contents) => {
669 // Special case for `Box<T>`
670 let box_ty = expr_ty(bcx, expr);
671 let contents_ty = expr_ty(bcx, &contents);
674 trans_uniq_expr(bcx, expr, box_ty, &contents, contents_ty)
676 _ => bcx.sess().span_bug(expr.span,
677 "expected unique box")
681 hir::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &lit),
682 hir::ExprBinary(op, ref lhs, ref rhs) => {
683 trans_binary(bcx, expr, op, &lhs, &rhs)
685 hir::ExprUnary(op, ref x) => {
686 trans_unary(bcx, expr, op, &x)
688 hir::ExprAddrOf(_, ref x) => {
690 hir::ExprRepeat(..) | hir::ExprVec(..) => {
691 // Special case for slices.
692 let cleanup_debug_loc =
693 debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
697 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
698 let datum = unpack_datum!(
699 bcx, tvec::trans_slice_vec(bcx, expr, &x));
700 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
701 DatumBlock::new(bcx, datum)
704 trans_addr_of(bcx, expr, &x)
708 hir::ExprCast(ref val, _) => {
709 // Datum output mode means this is a scalar cast:
710 trans_imm_cast(bcx, &val, expr.id)
713 bcx.tcx().sess.span_bug(
715 &format!("trans_rvalue_datum_unadjusted reached \
716 fall-through case: {:?}",
722 fn trans_field<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
725 -> DatumBlock<'blk, 'tcx, Expr> where
726 F: FnOnce(&'blk TyCtxt<'tcx>, &VariantInfo<'tcx>) -> usize,
729 let _icx = push_ctxt("trans_rec_field");
731 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
732 let bare_ty = base_datum.ty;
733 let repr = adt::represent_type(bcx.ccx(), bare_ty);
734 let vinfo = VariantInfo::from_ty(bcx.tcx(), bare_ty, None);
736 let ix = get_idx(bcx.tcx(), &vinfo);
737 let d = base_datum.get_element(
741 adt::trans_field_ptr(bcx, &repr, srcval, vinfo.discr, ix)
744 if type_is_sized(bcx.tcx(), d.ty) {
745 DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
747 let scratch = rvalue_scratch_datum(bcx, d.ty, "");
748 Store(bcx, d.val, get_dataptr(bcx, scratch.val));
749 let info = Load(bcx, get_meta(bcx, base_datum.val));
750 Store(bcx, info, get_meta(bcx, scratch.val));
752 // Always generate an lvalue datum, because this pointer doesn't own
753 // the data and cleanup is scheduled elsewhere.
754 DatumBlock::new(bcx, Datum::new(scratch.val, scratch.ty, LvalueExpr(d.kind)))
758 /// Translates `base.field`.
759 fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
762 -> DatumBlock<'blk, 'tcx, Expr> {
763 trans_field(bcx, base, |_, vinfo| vinfo.field_index(field))
766 /// Translates `base.<idx>`.
767 fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
770 -> DatumBlock<'blk, 'tcx, Expr> {
771 trans_field(bcx, base, |_, _| idx)
774 fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
775 index_expr: &hir::Expr,
778 method_call: MethodCall)
779 -> DatumBlock<'blk, 'tcx, Expr> {
780 //! Translates `base[idx]`.
782 let _icx = push_ctxt("trans_index");
786 let index_expr_debug_loc = index_expr.debug_loc();
788 // Check for overloaded index.
789 let method = ccx.tcx().tables.borrow().method_map.get(&method_call).cloned();
790 let elt_datum = match method {
792 let method_ty = monomorphize_type(bcx, method.ty);
794 let base_datum = unpack_datum!(bcx, trans(bcx, base));
796 // Translate index expression.
797 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
799 let ref_ty = // invoked methods have LB regions instantiated:
800 bcx.tcx().no_late_bound_regions(&method_ty.fn_ret()).unwrap().unwrap();
801 let elt_ty = match ref_ty.builtin_deref(true, ty::NoPreference) {
803 bcx.tcx().sess.span_bug(index_expr.span,
804 "index method didn't return a \
805 dereferenceable type?!")
807 Some(elt_tm) => elt_tm.ty,
810 // Overloaded. Invoke the index() method, which basically
811 // yields a `&T` pointer. We can then proceed down the
812 // normal path (below) to dereference that `&T`.
813 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_index_elt");
815 bcx = Callee::method(bcx, method)
816 .call(bcx, index_expr_debug_loc,
817 ArgOverloadedOp(base_datum, Some(ix_datum)),
818 Some(SaveIn(scratch.val))).bcx;
820 let datum = scratch.to_expr_datum();
821 let lval = Lvalue::new("expr::trans_index overload");
822 if type_is_sized(bcx.tcx(), elt_ty) {
823 Datum::new(datum.to_llscalarish(bcx), elt_ty, LvalueExpr(lval))
825 Datum::new(datum.val, elt_ty, LvalueExpr(lval))
829 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
833 // Translate index expression and cast to a suitable LLVM integer.
834 // Rust is less strict than LLVM in this regard.
835 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
836 let ix_val = ix_datum.to_llscalarish(bcx);
837 let ix_size = machine::llbitsize_of_real(bcx.ccx(),
839 let int_size = machine::llbitsize_of_real(bcx.ccx(),
842 if ix_size < int_size {
843 if expr_ty(bcx, idx).is_signed() {
844 SExt(bcx, ix_val, ccx.int_type())
845 } else { ZExt(bcx, ix_val, ccx.int_type()) }
846 } else if ix_size > int_size {
847 Trunc(bcx, ix_val, ccx.int_type())
853 let unit_ty = base_datum.ty.sequence_element_type(bcx.tcx());
855 let (base, len) = base_datum.get_vec_base_and_len(bcx);
857 debug!("trans_index: base {}", bcx.val_to_string(base));
858 debug!("trans_index: len {}", bcx.val_to_string(len));
860 let bounds_check = ICmp(bcx,
864 index_expr_debug_loc);
865 let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
866 let expected = Call(bcx,
868 &[bounds_check, C_bool(ccx, false)],
870 index_expr_debug_loc);
871 bcx = with_cond(bcx, expected, |bcx| {
872 controlflow::trans_fail_bounds_check(bcx,
873 expr_info(index_expr),
877 let elt = InBoundsGEP(bcx, base, &[ix_val]);
878 let elt = PointerCast(bcx, elt, type_of::type_of(ccx, unit_ty).ptr_to());
879 let lval = Lvalue::new("expr::trans_index fallback");
880 Datum::new(elt, unit_ty, LvalueExpr(lval))
884 DatumBlock::new(bcx, elt_datum)
887 fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
888 ref_expr: &hir::Expr,
890 -> DatumBlock<'blk, 'tcx, Expr> {
891 //! Translates a reference to a path.
893 let _icx = push_ctxt("trans_def_lvalue");
895 Def::Static(did, _) => {
896 let const_ty = expr_ty(bcx, ref_expr);
897 let val = get_static_val(bcx.ccx(), did, const_ty);
898 let lval = Lvalue::new("expr::trans_def");
899 DatumBlock::new(bcx, Datum::new(val, const_ty, LvalueExpr(lval)))
901 Def::Local(..) | Def::Upvar(..) => {
902 DatumBlock::new(bcx, trans_local_var(bcx, def).to_expr_datum())
905 bcx.sess().span_bug(ref_expr.span,
906 &format!("{:?} should not reach expr::trans_def", def))
911 fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
913 -> Block<'blk, 'tcx> {
915 let _icx = push_ctxt("trans_rvalue_stmt");
917 if bcx.unreachable.get() {
921 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
924 hir::ExprBreak(label_opt) => {
925 controlflow::trans_break(bcx, expr, label_opt.map(|l| l.node.name))
927 hir::ExprType(ref e, _) => {
928 trans_into(bcx, &e, Ignore)
930 hir::ExprAgain(label_opt) => {
931 controlflow::trans_cont(bcx, expr, label_opt.map(|l| l.node.name))
933 hir::ExprRet(ref ex) => {
934 // Check to see if the return expression itself is reachable.
935 // This can occur when the inner expression contains a return
936 let reachable = if let Some(ref cfg) = bcx.fcx.cfg {
937 cfg.node_is_reachable(expr.id)
943 controlflow::trans_ret(bcx, expr, ex.as_ref().map(|e| &**e))
945 // If it's not reachable, just translate the inner expression
946 // directly. This avoids having to manage a return slot when
947 // it won't actually be used anyway.
948 if let &Some(ref x) = ex {
949 bcx = trans_into(bcx, &x, Ignore);
951 // Mark the end of the block as unreachable. Once we get to
952 // a return expression, there's no more we should be doing
958 hir::ExprWhile(ref cond, ref body, _) => {
959 controlflow::trans_while(bcx, expr, &cond, &body)
961 hir::ExprLoop(ref body, _) => {
962 controlflow::trans_loop(bcx, expr, &body)
964 hir::ExprAssign(ref dst, ref src) => {
965 let src_datum = unpack_datum!(bcx, trans(bcx, &src));
966 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &dst, "assign"));
968 if bcx.fcx.type_needs_drop(dst_datum.ty) {
969 // If there are destructors involved, make sure we
970 // are copying from an rvalue, since that cannot possible
971 // alias an lvalue. We are concerned about code like:
979 // where e.g. a : Option<Foo> and a.b :
980 // Option<Foo>. In that case, freeing `a` before the
981 // assignment may also free `a.b`!
983 // We could avoid this intermediary with some analysis
984 // to determine whether `dst` may possibly own `src`.
985 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
986 let src_datum = unpack_datum!(
987 bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
988 let opt_hint_datum = dst_datum.kind.drop_flag_info.hint_datum(bcx);
989 let opt_hint_val = opt_hint_datum.map(|d|d.to_value());
991 // 1. Drop the data at the destination, passing the
992 // drop-hint in case the lvalue has already been
994 bcx = glue::drop_ty_core(bcx,
1001 // 2. We are overwriting the destination; ensure that
1002 // its drop-hint (if any) says "initialized."
1003 if let Some(hint_val) = opt_hint_val {
1004 let hint_llval = hint_val.value();
1005 let drop_needed = C_u8(bcx.fcx.ccx, adt::DTOR_NEEDED_HINT);
1006 Store(bcx, drop_needed, hint_llval);
1008 src_datum.store_to(bcx, dst_datum.val)
1010 src_datum.store_to(bcx, dst_datum.val)
1013 hir::ExprAssignOp(op, ref dst, ref src) => {
1014 let method = bcx.tcx().tables
1017 .get(&MethodCall::expr(expr.id)).cloned();
1019 if let Some(method) = method {
1020 let dst = unpack_datum!(bcx, trans(bcx, &dst));
1021 let src_datum = unpack_datum!(bcx, trans(bcx, &src));
1023 Callee::method(bcx, method)
1024 .call(bcx, expr.debug_loc(),
1025 ArgOverloadedOp(dst, Some(src_datum)), None).bcx
1027 trans_assign_op(bcx, expr, op, &dst, &src)
1030 hir::ExprInlineAsm(ref a) => {
1031 asm::trans_inline_asm(bcx, a)
1034 bcx.tcx().sess.span_bug(
1036 &format!("trans_rvalue_stmt_unadjusted reached \
1037 fall-through case: {:?}",
1043 fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1046 -> Block<'blk, 'tcx> {
1047 let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
1050 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
1052 // Entry into the method table if this is an overloaded call/op.
1053 let method_call = MethodCall::expr(expr.id);
1056 hir::ExprType(ref e, _) => {
1057 trans_into(bcx, &e, dest)
1059 hir::ExprPath(..) => {
1060 trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
1062 hir::ExprIf(ref cond, ref thn, ref els) => {
1063 controlflow::trans_if(bcx, expr.id, &cond, &thn, els.as_ref().map(|e| &**e), dest)
1065 hir::ExprMatch(ref discr, ref arms, _) => {
1066 _match::trans_match(bcx, expr, &discr, &arms[..], dest)
1068 hir::ExprBlock(ref blk) => {
1069 controlflow::trans_block(bcx, &blk, dest)
1071 hir::ExprStruct(_, ref fields, ref base) => {
1074 base.as_ref().map(|e| &**e),
1077 node_id_type(bcx, expr.id),
1080 hir::ExprTup(ref args) => {
1081 let numbered_fields: Vec<(usize, &hir::Expr)> =
1082 args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
1086 &numbered_fields[..],
1091 hir::ExprLit(ref lit) => {
1093 ast::LitKind::Str(ref s, _) => {
1094 tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
1099 .span_bug(expr.span,
1100 "trans_rvalue_dps_unadjusted shouldn't be \
1101 translating this type of literal")
1105 hir::ExprVec(..) | hir::ExprRepeat(..) => {
1106 tvec::trans_fixed_vstore(bcx, expr, dest)
1108 hir::ExprClosure(_, ref decl, ref body) => {
1109 let dest = match dest {
1110 SaveIn(lldest) => closure::Dest::SaveIn(bcx, lldest),
1111 Ignore => closure::Dest::Ignore(bcx.ccx())
1114 // NB. To get the id of the closure, we don't use
1115 // `local_def_id(id)`, but rather we extract the closure
1116 // def-id from the expr's type. This is because this may
1117 // be an inlined expression from another crate, and we
1118 // want to get the ORIGINAL closure def-id, since that is
1119 // the key we need to find the closure-kind and
1120 // closure-type etc.
1121 let (def_id, substs) = match expr_ty(bcx, expr).sty {
1122 ty::TyClosure(def_id, ref substs) => (def_id, substs),
1124 bcx.tcx().sess.span_bug(
1126 &format!("closure expr without closure type: {:?}", t)),
1129 closure::trans_closure_expr(dest,
1135 &expr.attrs).unwrap_or(bcx)
1137 hir::ExprCall(ref f, ref args) => {
1138 let method = bcx.tcx().tables.borrow().method_map.get(&method_call).cloned();
1139 let (callee, args) = if let Some(method) = method {
1140 let mut all_args = vec![&**f];
1141 all_args.extend(args.iter().map(|e| &**e));
1143 (Callee::method(bcx, method), ArgOverloadedCall(all_args))
1145 let f = unpack_datum!(bcx, trans(bcx, f));
1147 ty::TyFnDef(def_id, substs, _) => {
1148 Callee::def(bcx.ccx(), def_id, substs, f.ty)
1151 let f = unpack_datum!(bcx,
1152 f.to_rvalue_datum(bcx, "callee"));
1156 bcx.tcx().sess.span_bug(expr.span,
1157 &format!("type of callee is not a fn: {}", f.ty));
1161 callee.call(bcx, expr.debug_loc(), args, Some(dest)).bcx
1163 hir::ExprMethodCall(_, _, ref args) => {
1164 Callee::method_call(bcx, method_call)
1165 .call(bcx, expr.debug_loc(), ArgExprs(&args), Some(dest)).bcx
1167 hir::ExprBinary(op, ref lhs, ref rhs_expr) => {
1168 // if not overloaded, would be RvalueDatumExpr
1169 let lhs = unpack_datum!(bcx, trans(bcx, &lhs));
1170 let mut rhs = unpack_datum!(bcx, trans(bcx, &rhs_expr));
1171 if !rustc_front::util::is_by_value_binop(op.node) {
1172 rhs = unpack_datum!(bcx, auto_ref(bcx, rhs, rhs_expr));
1175 Callee::method_call(bcx, method_call)
1176 .call(bcx, expr.debug_loc(),
1177 ArgOverloadedOp(lhs, Some(rhs)), Some(dest)).bcx
1179 hir::ExprUnary(_, ref subexpr) => {
1180 // if not overloaded, would be RvalueDatumExpr
1181 let arg = unpack_datum!(bcx, trans(bcx, &subexpr));
1183 Callee::method_call(bcx, method_call)
1184 .call(bcx, expr.debug_loc(),
1185 ArgOverloadedOp(arg, None), Some(dest)).bcx
1187 hir::ExprCast(..) => {
1188 // Trait casts used to come this way, now they should be coercions.
1189 bcx.tcx().sess.span_bug(expr.span, "DPS expr_cast (residual trait cast?)")
1191 hir::ExprAssignOp(op, _, _) => {
1192 bcx.tcx().sess.span_bug(
1194 &format!("augmented assignment `{}=` should always be a rvalue_stmt",
1195 rustc_front::util::binop_to_string(op.node)))
1198 bcx.tcx().sess.span_bug(
1200 &format!("trans_rvalue_dps_unadjusted reached fall-through \
1207 fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1208 ref_expr: &hir::Expr,
1211 -> Block<'blk, 'tcx> {
1212 let _icx = push_ctxt("trans_def_dps_unadjusted");
1214 let lldest = match dest {
1215 SaveIn(lldest) => lldest,
1216 Ignore => { return bcx; }
1219 let ty = expr_ty(bcx, ref_expr);
1220 if let ty::TyFnDef(..) = ty.sty {
1221 // Zero-sized function or ctor.
1226 Def::Variant(tid, vid) => {
1227 let variant = bcx.tcx().lookup_adt_def(tid).variant_with_id(vid);
1229 let ty = expr_ty(bcx, ref_expr);
1230 let repr = adt::represent_type(bcx.ccx(), ty);
1231 adt::trans_set_discr(bcx, &repr, lldest, Disr::from(variant.disr_val));
1234 Def::Struct(..) => {
1236 ty::TyStruct(def, _) if def.has_dtor() => {
1237 let repr = adt::represent_type(bcx.ccx(), ty);
1238 adt::trans_set_discr(bcx, &repr, lldest, Disr(0));
1245 bcx.tcx().sess.span_bug(ref_expr.span, &format!(
1246 "Non-DPS def {:?} referened by {}",
1247 def, bcx.node_id_to_string(ref_expr.id)));
1252 /// Translates a reference to a local variable or argument. This always results in an lvalue datum.
1253 pub fn trans_local_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1255 -> Datum<'tcx, Lvalue> {
1256 let _icx = push_ctxt("trans_local_var");
1259 Def::Upvar(_, nid, _, _) => {
1260 // Can't move upvars, so this is never a ZeroMemLastUse.
1261 let local_ty = node_id_type(bcx, nid);
1262 let lval = Lvalue::new_with_hint("expr::trans_local_var (upvar)",
1263 bcx, nid, HintKind::ZeroAndMaintain);
1264 match bcx.fcx.llupvars.borrow().get(&nid) {
1265 Some(&val) => Datum::new(val, local_ty, lval),
1267 bcx.sess().bug(&format!(
1268 "trans_local_var: no llval for upvar {} found",
1273 Def::Local(_, nid) => {
1274 let datum = match bcx.fcx.lllocals.borrow().get(&nid) {
1277 bcx.sess().bug(&format!(
1278 "trans_local_var: no datum for local/arg {} found",
1282 debug!("take_local(nid={}, v={}, ty={})",
1283 nid, bcx.val_to_string(datum.val), datum.ty);
1287 bcx.sess().unimpl(&format!(
1288 "unsupported def type in trans_local_var: {:?}",
1294 fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1295 fields: &[hir::Field],
1296 base: Option<&hir::Expr>,
1297 expr_span: codemap::Span,
1298 expr_id: ast::NodeId,
1300 dest: Dest) -> Block<'blk, 'tcx> {
1301 let _icx = push_ctxt("trans_rec");
1303 let tcx = bcx.tcx();
1304 let vinfo = VariantInfo::of_node(tcx, ty, expr_id);
1306 let mut need_base = vec![true; vinfo.fields.len()];
1308 let numbered_fields = fields.iter().map(|field| {
1309 let pos = vinfo.field_index(field.name.node);
1310 need_base[pos] = false;
1312 }).collect::<Vec<_>>();
1314 let optbase = match base {
1315 Some(base_expr) => {
1316 let mut leftovers = Vec::new();
1317 for (i, b) in need_base.iter().enumerate() {
1319 leftovers.push((i, vinfo.fields[i].1));
1322 Some(StructBaseInfo {expr: base_expr,
1323 fields: leftovers })
1326 if need_base.iter().any(|b| *b) {
1327 tcx.sess.span_bug(expr_span, "missing fields and no base expr")
1339 DebugLoc::At(expr_id, expr_span))
1342 /// Information that `trans_adt` needs in order to fill in the fields
1343 /// of a struct copied from a base struct (e.g., from an expression
1344 /// like `Foo { a: b, ..base }`.
1346 /// Note that `fields` may be empty; the base expression must always be
1347 /// evaluated for side-effects.
1348 pub struct StructBaseInfo<'a, 'tcx> {
1349 /// The base expression; will be evaluated after all explicit fields.
1350 expr: &'a hir::Expr,
1351 /// The indices of fields to copy paired with their types.
1352 fields: Vec<(usize, Ty<'tcx>)>
1355 /// Constructs an ADT instance:
1357 /// - `fields` should be a list of field indices paired with the
1358 /// expression to store into that field. The initializers will be
1359 /// evaluated in the order specified by `fields`.
1361 /// - `optbase` contains information on the base struct (if any) from
1362 /// which remaining fields are copied; see comments on `StructBaseInfo`.
1363 pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1366 fields: &[(usize, &hir::Expr)],
1367 optbase: Option<StructBaseInfo<'a, 'tcx>>,
1369 debug_location: DebugLoc)
1370 -> Block<'blk, 'tcx> {
1371 let _icx = push_ctxt("trans_adt");
1373 let repr = adt::represent_type(bcx.ccx(), ty);
1375 debug_location.apply(bcx.fcx);
1377 // If we don't care about the result, just make a
1378 // temporary stack slot
1379 let addr = match dest {
1382 let llresult = alloc_ty(bcx, ty, "temp");
1383 call_lifetime_start(bcx, llresult);
1388 debug!("trans_adt");
1390 // This scope holds intermediates that must be cleaned should
1391 // panic occur before the ADT as a whole is ready.
1392 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1395 // Issue 23112: The original logic appeared vulnerable to same
1396 // order-of-eval bug. But, SIMD values are tuple-structs;
1397 // i.e. functional record update (FRU) syntax is unavailable.
1399 // To be safe, double-check that we did not get here via FRU.
1400 assert!(optbase.is_none());
1402 // This is the constructor of a SIMD type, such types are
1403 // always primitive machine types and so do not have a
1404 // destructor or require any clean-up.
1405 let llty = type_of::type_of(bcx.ccx(), ty);
1407 // keep a vector as a register, and running through the field
1408 // `insertelement`ing them directly into that register
1409 // (i.e. avoid GEPi and `store`s to an alloca) .
1410 let mut vec_val = C_undef(llty);
1412 for &(i, ref e) in fields {
1413 let block_datum = trans(bcx, &e);
1414 bcx = block_datum.bcx;
1415 let position = C_uint(bcx.ccx(), i);
1416 let value = block_datum.datum.to_llscalarish(bcx);
1417 vec_val = InsertElement(bcx, vec_val, value, position);
1419 Store(bcx, vec_val, addr);
1420 } else if let Some(base) = optbase {
1421 // Issue 23112: If there is a base, then order-of-eval
1422 // requires field expressions eval'ed before base expression.
1424 // First, trans field expressions to temporary scratch values.
1425 let scratch_vals: Vec<_> = fields.iter().map(|&(i, ref e)| {
1426 let datum = unpack_datum!(bcx, trans(bcx, &e));
1430 debug_location.apply(bcx.fcx);
1432 // Second, trans the base to the dest.
1433 assert_eq!(discr, Disr(0));
1435 let addr = adt::MaybeSizedValue::sized(addr);
1436 match expr_kind(bcx.tcx(), &base.expr) {
1437 ExprKind::RvalueDps | ExprKind::RvalueDatum if !bcx.fcx.type_needs_drop(ty) => {
1438 bcx = trans_into(bcx, &base.expr, SaveIn(addr.value));
1440 ExprKind::RvalueStmt => {
1441 bcx.tcx().sess.bug("unexpected expr kind for struct base expr")
1444 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &base.expr, "base"));
1445 for &(i, t) in &base.fields {
1446 let datum = base_datum.get_element(
1447 bcx, t, |srcval| adt::trans_field_ptr(bcx, &repr, srcval, discr, i));
1448 assert!(type_is_sized(bcx.tcx(), datum.ty));
1449 let dest = adt::trans_field_ptr(bcx, &repr, addr, discr, i);
1450 bcx = datum.store_to(bcx, dest);
1455 // Finally, move scratch field values into actual field locations
1456 for (i, datum) in scratch_vals {
1457 let dest = adt::trans_field_ptr(bcx, &repr, addr, discr, i);
1458 bcx = datum.store_to(bcx, dest);
1461 // No base means we can write all fields directly in place.
1462 let addr = adt::MaybeSizedValue::sized(addr);
1463 for &(i, ref e) in fields {
1464 let dest = adt::trans_field_ptr(bcx, &repr, addr, discr, i);
1465 let e_ty = expr_ty_adjusted(bcx, &e);
1466 bcx = trans_into(bcx, &e, SaveIn(dest));
1467 let scope = cleanup::CustomScope(custom_cleanup_scope);
1468 fcx.schedule_lifetime_end(scope, dest);
1469 // FIXME: nonzeroing move should generalize to fields
1470 fcx.schedule_drop_mem(scope, dest, e_ty, None);
1474 adt::trans_set_discr(bcx, &repr, addr, discr);
1476 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1478 // If we don't care about the result drop the temporary we made
1482 bcx = glue::drop_ty(bcx, addr, ty, debug_location);
1483 base::call_lifetime_end(bcx, addr);
1490 fn trans_immediate_lit<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1493 -> DatumBlock<'blk, 'tcx, Expr> {
1494 // must not be a string constant, that is a RvalueDpsExpr
1495 let _icx = push_ctxt("trans_immediate_lit");
1496 let ty = expr_ty(bcx, expr);
1497 let v = consts::const_lit(bcx.ccx(), expr, lit);
1498 immediate_rvalue_bcx(bcx, v, ty).to_expr_datumblock()
1501 fn trans_unary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1504 sub_expr: &hir::Expr)
1505 -> DatumBlock<'blk, 'tcx, Expr> {
1506 let ccx = bcx.ccx();
1508 let _icx = push_ctxt("trans_unary_datum");
1510 let method_call = MethodCall::expr(expr.id);
1512 // The only overloaded operator that is translated to a datum
1513 // is an overloaded deref, since it is always yields a `&T`.
1514 // Otherwise, we should be in the RvalueDpsExpr path.
1515 assert!(op == hir::UnDeref || !ccx.tcx().is_method_call(expr.id));
1517 let un_ty = expr_ty(bcx, expr);
1519 let debug_loc = expr.debug_loc();
1523 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1524 let llresult = Not(bcx, datum.to_llscalarish(bcx), debug_loc);
1525 immediate_rvalue_bcx(bcx, llresult, un_ty).to_expr_datumblock()
1528 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1529 let val = datum.to_llscalarish(bcx);
1530 let (bcx, llneg) = {
1532 let result = FNeg(bcx, val, debug_loc);
1535 let is_signed = un_ty.is_signed();
1536 let result = Neg(bcx, val, debug_loc);
1537 let bcx = if bcx.ccx().check_overflow() && is_signed {
1538 let (llty, min) = base::llty_and_min_for_signed_ty(bcx, un_ty);
1539 let is_min = ICmp(bcx, llvm::IntEQ, val,
1540 C_integral(llty, min, true), debug_loc);
1541 with_cond(bcx, is_min, |bcx| {
1542 let msg = InternedString::new(
1543 "attempted to negate with overflow");
1544 controlflow::trans_fail(bcx, expr_info(expr), msg)
1552 immediate_rvalue_bcx(bcx, llneg, un_ty).to_expr_datumblock()
1555 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1556 deref_once(bcx, expr, datum, method_call)
1561 fn trans_uniq_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1562 box_expr: &hir::Expr,
1564 contents: &hir::Expr,
1565 contents_ty: Ty<'tcx>)
1566 -> DatumBlock<'blk, 'tcx, Expr> {
1567 let _icx = push_ctxt("trans_uniq_expr");
1569 assert!(type_is_sized(bcx.tcx(), contents_ty));
1570 let llty = type_of::type_of(bcx.ccx(), contents_ty);
1571 let size = llsize_of(bcx.ccx(), llty);
1572 let align = C_uint(bcx.ccx(), type_of::align_of(bcx.ccx(), contents_ty));
1573 let llty_ptr = llty.ptr_to();
1574 let Result { bcx, val } = malloc_raw_dyn(bcx,
1579 box_expr.debug_loc());
1580 // Unique boxes do not allocate for zero-size types. The standard library
1581 // may assume that `free` is never called on the pointer returned for
1582 // `Box<ZeroSizeType>`.
1583 let bcx = if llsize_of_alloc(bcx.ccx(), llty) == 0 {
1584 trans_into(bcx, contents, SaveIn(val))
1586 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1587 fcx.schedule_free_value(cleanup::CustomScope(custom_cleanup_scope),
1588 val, cleanup::HeapExchange, contents_ty);
1589 let bcx = trans_into(bcx, contents, SaveIn(val));
1590 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1593 immediate_rvalue_bcx(bcx, val, box_ty).to_expr_datumblock()
1596 fn trans_addr_of<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1598 subexpr: &hir::Expr)
1599 -> DatumBlock<'blk, 'tcx, Expr> {
1600 let _icx = push_ctxt("trans_addr_of");
1602 let sub_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, subexpr, "addr_of"));
1603 let ty = expr_ty(bcx, expr);
1604 if !type_is_sized(bcx.tcx(), sub_datum.ty) {
1605 // Always generate an lvalue datum, because this pointer doesn't own
1606 // the data and cleanup is scheduled elsewhere.
1607 DatumBlock::new(bcx, Datum::new(sub_datum.val, ty, LvalueExpr(sub_datum.kind)))
1609 // Sized value, ref to a thin pointer
1610 immediate_rvalue_bcx(bcx, sub_datum.val, ty).to_expr_datumblock()
1614 fn trans_scalar_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1615 binop_expr: &hir::Expr,
1618 lhs: Datum<'tcx, Rvalue>,
1619 rhs: Datum<'tcx, Rvalue>)
1620 -> DatumBlock<'blk, 'tcx, Expr>
1622 let _icx = push_ctxt("trans_scalar_binop");
1624 let tcx = bcx.tcx();
1626 assert!(!lhs_t.is_simd());
1627 let is_float = lhs_t.is_fp();
1628 let is_signed = lhs_t.is_signed();
1629 let info = expr_info(binop_expr);
1631 let binop_debug_loc = binop_expr.debug_loc();
1634 let lhs = lhs.to_llscalarish(bcx);
1635 let rhs = rhs.to_llscalarish(bcx);
1636 let val = match op.node {
1639 FAdd(bcx, lhs, rhs, binop_debug_loc)
1641 let (newbcx, res) = with_overflow_check(
1642 bcx, OverflowOp::Add, info, lhs_t, lhs, rhs, binop_debug_loc);
1649 FSub(bcx, lhs, rhs, binop_debug_loc)
1651 let (newbcx, res) = with_overflow_check(
1652 bcx, OverflowOp::Sub, info, lhs_t, lhs, rhs, binop_debug_loc);
1659 FMul(bcx, lhs, rhs, binop_debug_loc)
1661 let (newbcx, res) = with_overflow_check(
1662 bcx, OverflowOp::Mul, info, lhs_t, lhs, rhs, binop_debug_loc);
1669 FDiv(bcx, lhs, rhs, binop_debug_loc)
1671 // Only zero-check integers; fp /0 is NaN
1672 bcx = base::fail_if_zero_or_overflows(bcx,
1673 expr_info(binop_expr),
1679 SDiv(bcx, lhs, rhs, binop_debug_loc)
1681 UDiv(bcx, lhs, rhs, binop_debug_loc)
1687 // LLVM currently always lowers the `frem` instructions appropriate
1688 // library calls typically found in libm. Notably f64 gets wired up
1689 // to `fmod` and f32 gets wired up to `fmodf`. Inconveniently for
1690 // us, 32-bit MSVC does not actually have a `fmodf` symbol, it's
1691 // instead just an inline function in a header that goes up to a
1692 // f64, uses `fmod`, and then comes back down to a f32.
1694 // Although LLVM knows that `fmodf` doesn't exist on MSVC, it will
1695 // still unconditionally lower frem instructions over 32-bit floats
1696 // to a call to `fmodf`. To work around this we special case MSVC
1697 // 32-bit float rem instructions and instead do the call out to
1698 // `fmod` ourselves.
1700 // Note that this is currently duplicated with src/libcore/ops.rs
1701 // which does the same thing, and it would be nice to perhaps unify
1702 // these two implementations on day! Also note that we call `fmod`
1703 // for both 32 and 64-bit floats because if we emit any FRem
1704 // instruction at all then LLVM is capable of optimizing it into a
1705 // 32-bit FRem (which we're trying to avoid).
1706 let use_fmod = tcx.sess.target.target.options.is_like_msvc &&
1707 tcx.sess.target.target.arch == "x86";
1709 let f64t = Type::f64(bcx.ccx());
1710 let fty = Type::func(&[f64t, f64t], &f64t);
1711 let llfn = declare::declare_cfn(bcx.ccx(), "fmod", fty,
1713 if lhs_t == tcx.types.f32 {
1714 let lhs = FPExt(bcx, lhs, f64t);
1715 let rhs = FPExt(bcx, rhs, f64t);
1716 let res = Call(bcx, llfn, &[lhs, rhs], None, binop_debug_loc);
1717 FPTrunc(bcx, res, Type::f32(bcx.ccx()))
1719 Call(bcx, llfn, &[lhs, rhs], None, binop_debug_loc)
1722 FRem(bcx, lhs, rhs, binop_debug_loc)
1725 // Only zero-check integers; fp %0 is NaN
1726 bcx = base::fail_if_zero_or_overflows(bcx,
1727 expr_info(binop_expr),
1728 op, lhs, rhs, lhs_t);
1730 SRem(bcx, lhs, rhs, binop_debug_loc)
1732 URem(bcx, lhs, rhs, binop_debug_loc)
1736 hir::BiBitOr => Or(bcx, lhs, rhs, binop_debug_loc),
1737 hir::BiBitAnd => And(bcx, lhs, rhs, binop_debug_loc),
1738 hir::BiBitXor => Xor(bcx, lhs, rhs, binop_debug_loc),
1740 let (newbcx, res) = with_overflow_check(
1741 bcx, OverflowOp::Shl, info, lhs_t, lhs, rhs, binop_debug_loc);
1746 let (newbcx, res) = with_overflow_check(
1747 bcx, OverflowOp::Shr, info, lhs_t, lhs, rhs, binop_debug_loc);
1751 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiGe | hir::BiLe | hir::BiGt => {
1752 base::compare_scalar_types(bcx, lhs, rhs, lhs_t, op.node, binop_debug_loc)
1755 bcx.tcx().sess.span_bug(binop_expr.span, "unexpected binop");
1759 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1762 // refinement types would obviate the need for this
1763 enum lazy_binop_ty {
1768 fn trans_lazy_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1769 binop_expr: &hir::Expr,
1773 -> DatumBlock<'blk, 'tcx, Expr> {
1774 let _icx = push_ctxt("trans_lazy_binop");
1775 let binop_ty = expr_ty(bcx, binop_expr);
1778 let DatumBlock {bcx: past_lhs, datum: lhs} = trans(bcx, a);
1779 let lhs = lhs.to_llscalarish(past_lhs);
1781 if past_lhs.unreachable.get() {
1782 return immediate_rvalue_bcx(past_lhs, lhs, binop_ty).to_expr_datumblock();
1785 let join = fcx.new_id_block("join", binop_expr.id);
1786 let before_rhs = fcx.new_id_block("before_rhs", b.id);
1789 lazy_and => CondBr(past_lhs, lhs, before_rhs.llbb, join.llbb, DebugLoc::None),
1790 lazy_or => CondBr(past_lhs, lhs, join.llbb, before_rhs.llbb, DebugLoc::None)
1793 let DatumBlock {bcx: past_rhs, datum: rhs} = trans(before_rhs, b);
1794 let rhs = rhs.to_llscalarish(past_rhs);
1796 if past_rhs.unreachable.get() {
1797 return immediate_rvalue_bcx(join, lhs, binop_ty).to_expr_datumblock();
1800 Br(past_rhs, join.llbb, DebugLoc::None);
1801 let phi = Phi(join, Type::i1(bcx.ccx()), &[lhs, rhs],
1802 &[past_lhs.llbb, past_rhs.llbb]);
1804 return immediate_rvalue_bcx(join, phi, binop_ty).to_expr_datumblock();
1807 fn trans_binary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1812 -> DatumBlock<'blk, 'tcx, Expr> {
1813 let _icx = push_ctxt("trans_binary");
1814 let ccx = bcx.ccx();
1816 // if overloaded, would be RvalueDpsExpr
1817 assert!(!ccx.tcx().is_method_call(expr.id));
1821 trans_lazy_binop(bcx, expr, lazy_and, lhs, rhs)
1824 trans_lazy_binop(bcx, expr, lazy_or, lhs, rhs)
1828 let binop_ty = expr_ty(bcx, expr);
1830 let lhs = unpack_datum!(bcx, trans(bcx, lhs));
1831 let lhs = unpack_datum!(bcx, lhs.to_rvalue_datum(bcx, "binop_lhs"));
1832 debug!("trans_binary (expr {}): lhs={}",
1833 expr.id, lhs.to_string(ccx));
1834 let rhs = unpack_datum!(bcx, trans(bcx, rhs));
1835 let rhs = unpack_datum!(bcx, rhs.to_rvalue_datum(bcx, "binop_rhs"));
1836 debug!("trans_binary (expr {}): rhs={}",
1837 expr.id, rhs.to_string(ccx));
1839 if type_is_fat_ptr(ccx.tcx(), lhs.ty) {
1840 assert!(type_is_fat_ptr(ccx.tcx(), rhs.ty),
1841 "built-in binary operators on fat pointers are homogeneous");
1842 assert_eq!(binop_ty, bcx.tcx().types.bool);
1843 let val = base::compare_scalar_types(
1850 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1852 assert!(!type_is_fat_ptr(ccx.tcx(), rhs.ty),
1853 "built-in binary operators on fat pointers are homogeneous");
1854 trans_scalar_binop(bcx, expr, binop_ty, op, lhs, rhs)
1860 pub fn cast_is_noop<'tcx>(tcx: &TyCtxt<'tcx>,
1865 if let Some(&CastKind::CoercionCast) = tcx.cast_kinds.borrow().get(&expr.id) {
1869 match (t_in.builtin_deref(true, ty::NoPreference),
1870 t_out.builtin_deref(true, ty::NoPreference)) {
1871 (Some(ty::TypeAndMut{ ty: t_in, .. }), Some(ty::TypeAndMut{ ty: t_out, .. })) => {
1875 // This condition isn't redundant with the check for CoercionCast:
1876 // different types can be substituted into the same type, and
1877 // == equality can be overconservative if there are regions.
1883 fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1886 -> DatumBlock<'blk, 'tcx, Expr>
1888 use middle::ty::cast::CastTy::*;
1889 use middle::ty::cast::IntTy::*;
1891 fn int_cast(bcx: Block,
1898 let _icx = push_ctxt("int_cast");
1899 let srcsz = llsrctype.int_width();
1900 let dstsz = lldsttype.int_width();
1901 return if dstsz == srcsz {
1902 BitCast(bcx, llsrc, lldsttype)
1903 } else if srcsz > dstsz {
1904 TruncOrBitCast(bcx, llsrc, lldsttype)
1906 SExtOrBitCast(bcx, llsrc, lldsttype)
1908 ZExtOrBitCast(bcx, llsrc, lldsttype)
1912 fn float_cast(bcx: Block,
1918 let _icx = push_ctxt("float_cast");
1919 let srcsz = llsrctype.float_width();
1920 let dstsz = lldsttype.float_width();
1921 return if dstsz > srcsz {
1922 FPExt(bcx, llsrc, lldsttype)
1923 } else if srcsz > dstsz {
1924 FPTrunc(bcx, llsrc, lldsttype)
1928 let _icx = push_ctxt("trans_cast");
1930 let ccx = bcx.ccx();
1932 let t_in = expr_ty_adjusted(bcx, expr);
1933 let t_out = node_id_type(bcx, id);
1935 debug!("trans_cast({:?} as {:?})", t_in, t_out);
1936 let mut ll_t_in = type_of::arg_type_of(ccx, t_in);
1937 let ll_t_out = type_of::arg_type_of(ccx, t_out);
1938 // Convert the value to be cast into a ValueRef, either by-ref or
1939 // by-value as appropriate given its type:
1940 let mut datum = unpack_datum!(bcx, trans(bcx, expr));
1942 let datum_ty = monomorphize_type(bcx, datum.ty);
1944 if cast_is_noop(bcx.tcx(), expr, datum_ty, t_out) {
1946 return DatumBlock::new(bcx, datum);
1949 if type_is_fat_ptr(bcx.tcx(), t_in) {
1950 assert!(datum.kind.is_by_ref());
1951 if type_is_fat_ptr(bcx.tcx(), t_out) {
1952 return DatumBlock::new(bcx, Datum::new(
1953 PointerCast(bcx, datum.val, ll_t_out.ptr_to()),
1956 )).to_expr_datumblock();
1958 // Return the address
1959 return immediate_rvalue_bcx(bcx,
1961 Load(bcx, get_dataptr(bcx, datum.val)),
1963 t_out).to_expr_datumblock();
1967 let r_t_in = CastTy::from_ty(t_in).expect("bad input type for cast");
1968 let r_t_out = CastTy::from_ty(t_out).expect("bad output type for cast");
1970 let (llexpr, signed) = if let Int(CEnum) = r_t_in {
1971 let repr = adt::represent_type(ccx, t_in);
1972 let datum = unpack_datum!(
1973 bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
1974 let llexpr_ptr = datum.to_llref();
1975 let discr = adt::trans_get_discr(bcx, &repr, llexpr_ptr,
1976 Some(Type::i64(ccx)), true);
1977 ll_t_in = val_ty(discr);
1978 (discr, adt::is_discr_signed(&repr))
1980 (datum.to_llscalarish(bcx), t_in.is_signed())
1983 let newval = match (r_t_in, r_t_out) {
1984 (Ptr(_), Ptr(_)) | (FnPtr, Ptr(_)) | (RPtr(_), Ptr(_)) => {
1985 PointerCast(bcx, llexpr, ll_t_out)
1987 (Ptr(_), Int(_)) | (FnPtr, Int(_)) => PtrToInt(bcx, llexpr, ll_t_out),
1988 (Int(_), Ptr(_)) => IntToPtr(bcx, llexpr, ll_t_out),
1990 (Int(_), Int(_)) => int_cast(bcx, ll_t_out, ll_t_in, llexpr, signed),
1991 (Float, Float) => float_cast(bcx, ll_t_out, ll_t_in, llexpr),
1992 (Int(_), Float) if signed => SIToFP(bcx, llexpr, ll_t_out),
1993 (Int(_), Float) => UIToFP(bcx, llexpr, ll_t_out),
1994 (Float, Int(I)) => FPToSI(bcx, llexpr, ll_t_out),
1995 (Float, Int(_)) => FPToUI(bcx, llexpr, ll_t_out),
1997 _ => ccx.sess().span_bug(expr.span,
1998 &format!("translating unsupported cast: \
2004 return immediate_rvalue_bcx(bcx, newval, t_out).to_expr_datumblock();
2007 fn trans_assign_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2012 -> Block<'blk, 'tcx> {
2013 let _icx = push_ctxt("trans_assign_op");
2016 debug!("trans_assign_op(expr={:?})", expr);
2018 // User-defined operator methods cannot be used with `+=` etc right now
2019 assert!(!bcx.tcx().is_method_call(expr.id));
2021 // Evaluate LHS (destination), which should be an lvalue
2022 let dst = unpack_datum!(bcx, trans_to_lvalue(bcx, dst, "assign_op"));
2023 assert!(!bcx.fcx.type_needs_drop(dst.ty));
2024 let lhs = load_ty(bcx, dst.val, dst.ty);
2025 let lhs = immediate_rvalue(lhs, dst.ty);
2027 // Evaluate RHS - FIXME(#28160) this sucks
2028 let rhs = unpack_datum!(bcx, trans(bcx, &src));
2029 let rhs = unpack_datum!(bcx, rhs.to_rvalue_datum(bcx, "assign_op_rhs"));
2031 // Perform computation and store the result
2032 let result_datum = unpack_datum!(
2033 bcx, trans_scalar_binop(bcx, expr, dst.ty, op, lhs, rhs));
2034 return result_datum.store_to(bcx, dst.val);
2037 fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2038 datum: Datum<'tcx, Expr>,
2040 -> DatumBlock<'blk, 'tcx, Expr> {
2043 // Ensure cleanup of `datum` if not already scheduled and obtain
2044 // a "by ref" pointer.
2045 let lv_datum = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "autoref", expr.id));
2047 // Compute final type. Note that we are loose with the region and
2048 // mutability, since those things don't matter in trans.
2049 let referent_ty = lv_datum.ty;
2050 let ptr_ty = bcx.tcx().mk_imm_ref(bcx.tcx().mk_region(ty::ReStatic), referent_ty);
2052 // Construct the resulting datum. The right datum to return here would be an Lvalue datum,
2053 // because there is cleanup scheduled and the datum doesn't own the data, but for thin pointers
2054 // we microoptimize it to be an Rvalue datum to avoid the extra alloca and level of
2055 // indirection and for thin pointers, this has no ill effects.
2056 let kind = if type_is_sized(bcx.tcx(), referent_ty) {
2057 RvalueExpr(Rvalue::new(ByValue))
2059 LvalueExpr(lv_datum.kind)
2063 let llref = lv_datum.to_llref();
2064 DatumBlock::new(bcx, Datum::new(llref, ptr_ty, kind))
2067 fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2069 datum: Datum<'tcx, Expr>,
2071 -> DatumBlock<'blk, 'tcx, Expr> {
2073 let mut datum = datum;
2075 let method_call = MethodCall::autoderef(expr.id, i as u32);
2076 datum = unpack_datum!(bcx, deref_once(bcx, expr, datum, method_call));
2078 DatumBlock { bcx: bcx, datum: datum }
2081 fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2083 datum: Datum<'tcx, Expr>,
2084 method_call: MethodCall)
2085 -> DatumBlock<'blk, 'tcx, Expr> {
2086 let ccx = bcx.ccx();
2088 debug!("deref_once(expr={:?}, datum={}, method_call={:?})",
2090 datum.to_string(ccx),
2095 // Check for overloaded deref.
2096 let method = ccx.tcx().tables.borrow().method_map.get(&method_call).cloned();
2097 let datum = match method {
2099 let method_ty = monomorphize_type(bcx, method.ty);
2101 // Overloaded. Invoke the deref() method, which basically
2102 // converts from the `Smaht<T>` pointer that we have into
2103 // a `&T` pointer. We can then proceed down the normal
2104 // path (below) to dereference that `&T`.
2105 let datum = if method_call.autoderef == 0 {
2108 // Always perform an AutoPtr when applying an overloaded auto-deref
2109 unpack_datum!(bcx, auto_ref(bcx, datum, expr))
2112 let ref_ty = // invoked methods have their LB regions instantiated
2113 ccx.tcx().no_late_bound_regions(&method_ty.fn_ret()).unwrap().unwrap();
2114 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_deref");
2116 bcx = Callee::method(bcx, method)
2117 .call(bcx, expr.debug_loc(),
2118 ArgOverloadedOp(datum, None),
2119 Some(SaveIn(scratch.val))).bcx;
2120 scratch.to_expr_datum()
2123 // Not overloaded. We already have a pointer we know how to deref.
2128 let r = match datum.ty.sty {
2129 ty::TyBox(content_ty) => {
2130 // Make sure we have an lvalue datum here to get the
2131 // proper cleanups scheduled
2132 let datum = unpack_datum!(
2133 bcx, datum.to_lvalue_datum(bcx, "deref", expr.id));
2135 if type_is_sized(bcx.tcx(), content_ty) {
2136 let ptr = load_ty(bcx, datum.val, datum.ty);
2137 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr(datum.kind)))
2139 // A fat pointer and a DST lvalue have the same representation
2140 // just different types. Since there is no temporary for `*e`
2141 // here (because it is unsized), we cannot emulate the sized
2142 // object code path for running drop glue and free. Instead,
2143 // we schedule cleanup for `e`, turning it into an lvalue.
2145 let lval = Lvalue::new("expr::deref_once ty_uniq");
2146 let datum = Datum::new(datum.val, content_ty, LvalueExpr(lval));
2147 DatumBlock::new(bcx, datum)
2151 ty::TyRawPtr(ty::TypeAndMut { ty: content_ty, .. }) |
2152 ty::TyRef(_, ty::TypeAndMut { ty: content_ty, .. }) => {
2153 let lval = Lvalue::new("expr::deref_once ptr");
2154 if type_is_sized(bcx.tcx(), content_ty) {
2155 let ptr = datum.to_llscalarish(bcx);
2157 // Always generate an lvalue datum, even if datum.mode is
2158 // an rvalue. This is because datum.mode is only an
2159 // rvalue for non-owning pointers like &T or *T, in which
2160 // case cleanup *is* scheduled elsewhere, by the true
2161 // owner (or, in the case of *T, by the user).
2162 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr(lval)))
2164 // A fat pointer and a DST lvalue have the same representation
2165 // just different types.
2166 DatumBlock::new(bcx, Datum::new(datum.val, content_ty, LvalueExpr(lval)))
2171 bcx.tcx().sess.span_bug(
2173 &format!("deref invoked on expr of invalid type {:?}",
2178 debug!("deref_once(expr={}, method_call={:?}, result={})",
2179 expr.id, method_call, r.datum.to_string(ccx));
2194 fn codegen_strategy(&self) -> OverflowCodegen {
2195 use self::OverflowCodegen::{ViaIntrinsic, ViaInputCheck};
2197 OverflowOp::Add => ViaIntrinsic(OverflowOpViaIntrinsic::Add),
2198 OverflowOp::Sub => ViaIntrinsic(OverflowOpViaIntrinsic::Sub),
2199 OverflowOp::Mul => ViaIntrinsic(OverflowOpViaIntrinsic::Mul),
2201 OverflowOp::Shl => ViaInputCheck(OverflowOpViaInputCheck::Shl),
2202 OverflowOp::Shr => ViaInputCheck(OverflowOpViaInputCheck::Shr),
2207 enum OverflowCodegen {
2208 ViaIntrinsic(OverflowOpViaIntrinsic),
2209 ViaInputCheck(OverflowOpViaInputCheck),
2212 enum OverflowOpViaInputCheck { Shl, Shr, }
2215 enum OverflowOpViaIntrinsic { Add, Sub, Mul, }
2217 impl OverflowOpViaIntrinsic {
2218 fn to_intrinsic<'blk, 'tcx>(&self, bcx: Block<'blk, 'tcx>, lhs_ty: Ty) -> ValueRef {
2219 let name = self.to_intrinsic_name(bcx.tcx(), lhs_ty);
2220 bcx.ccx().get_intrinsic(&name)
2222 fn to_intrinsic_name(&self, tcx: &TyCtxt, ty: Ty) -> &'static str {
2223 use syntax::ast::IntTy::*;
2224 use syntax::ast::UintTy::*;
2225 use middle::ty::{TyInt, TyUint};
2227 let new_sty = match ty.sty {
2228 TyInt(Is) => match &tcx.sess.target.target.target_pointer_width[..] {
2231 _ => panic!("unsupported target word size")
2233 TyUint(Us) => match &tcx.sess.target.target.target_pointer_width[..] {
2234 "32" => TyUint(U32),
2235 "64" => TyUint(U64),
2236 _ => panic!("unsupported target word size")
2238 ref t @ TyUint(_) | ref t @ TyInt(_) => t.clone(),
2239 _ => panic!("tried to get overflow intrinsic for {:?} applied to non-int type",
2244 OverflowOpViaIntrinsic::Add => match new_sty {
2245 TyInt(I8) => "llvm.sadd.with.overflow.i8",
2246 TyInt(I16) => "llvm.sadd.with.overflow.i16",
2247 TyInt(I32) => "llvm.sadd.with.overflow.i32",
2248 TyInt(I64) => "llvm.sadd.with.overflow.i64",
2250 TyUint(U8) => "llvm.uadd.with.overflow.i8",
2251 TyUint(U16) => "llvm.uadd.with.overflow.i16",
2252 TyUint(U32) => "llvm.uadd.with.overflow.i32",
2253 TyUint(U64) => "llvm.uadd.with.overflow.i64",
2255 _ => unreachable!(),
2257 OverflowOpViaIntrinsic::Sub => match new_sty {
2258 TyInt(I8) => "llvm.ssub.with.overflow.i8",
2259 TyInt(I16) => "llvm.ssub.with.overflow.i16",
2260 TyInt(I32) => "llvm.ssub.with.overflow.i32",
2261 TyInt(I64) => "llvm.ssub.with.overflow.i64",
2263 TyUint(U8) => "llvm.usub.with.overflow.i8",
2264 TyUint(U16) => "llvm.usub.with.overflow.i16",
2265 TyUint(U32) => "llvm.usub.with.overflow.i32",
2266 TyUint(U64) => "llvm.usub.with.overflow.i64",
2268 _ => unreachable!(),
2270 OverflowOpViaIntrinsic::Mul => match new_sty {
2271 TyInt(I8) => "llvm.smul.with.overflow.i8",
2272 TyInt(I16) => "llvm.smul.with.overflow.i16",
2273 TyInt(I32) => "llvm.smul.with.overflow.i32",
2274 TyInt(I64) => "llvm.smul.with.overflow.i64",
2276 TyUint(U8) => "llvm.umul.with.overflow.i8",
2277 TyUint(U16) => "llvm.umul.with.overflow.i16",
2278 TyUint(U32) => "llvm.umul.with.overflow.i32",
2279 TyUint(U64) => "llvm.umul.with.overflow.i64",
2281 _ => unreachable!(),
2286 fn build_intrinsic_call<'blk, 'tcx>(&self, bcx: Block<'blk, 'tcx>,
2287 info: NodeIdAndSpan,
2288 lhs_t: Ty<'tcx>, lhs: ValueRef,
2290 binop_debug_loc: DebugLoc)
2291 -> (Block<'blk, 'tcx>, ValueRef) {
2292 let llfn = self.to_intrinsic(bcx, lhs_t);
2294 let val = Call(bcx, llfn, &[lhs, rhs], None, binop_debug_loc);
2295 let result = ExtractValue(bcx, val, 0); // iN operation result
2296 let overflow = ExtractValue(bcx, val, 1); // i1 "did it overflow?"
2298 let cond = ICmp(bcx, llvm::IntEQ, overflow, C_integral(Type::i1(bcx.ccx()), 1, false),
2301 let expect = bcx.ccx().get_intrinsic(&"llvm.expect.i1");
2302 Call(bcx, expect, &[cond, C_integral(Type::i1(bcx.ccx()), 0, false)],
2303 None, binop_debug_loc);
2306 base::with_cond(bcx, cond, |bcx|
2307 controlflow::trans_fail(bcx, info,
2308 InternedString::new("arithmetic operation overflowed")));
2314 impl OverflowOpViaInputCheck {
2315 fn build_with_input_check<'blk, 'tcx>(&self,
2316 bcx: Block<'blk, 'tcx>,
2317 info: NodeIdAndSpan,
2321 binop_debug_loc: DebugLoc)
2322 -> (Block<'blk, 'tcx>, ValueRef)
2324 let lhs_llty = val_ty(lhs);
2325 let rhs_llty = val_ty(rhs);
2327 // Panic if any bits are set outside of bits that we always
2330 // Note that the mask's value is derived from the LHS type
2331 // (since that is where the 32/64 distinction is relevant) but
2332 // the mask's type must match the RHS type (since they will
2333 // both be fed into an and-binop)
2334 let invert_mask = shift_mask_val(bcx, lhs_llty, rhs_llty, true);
2336 let outer_bits = And(bcx, rhs, invert_mask, binop_debug_loc);
2337 let cond = build_nonzero_check(bcx, outer_bits, binop_debug_loc);
2338 let result = match *self {
2339 OverflowOpViaInputCheck::Shl =>
2340 build_unchecked_lshift(bcx, lhs, rhs, binop_debug_loc),
2341 OverflowOpViaInputCheck::Shr =>
2342 build_unchecked_rshift(bcx, lhs_t, lhs, rhs, binop_debug_loc),
2345 base::with_cond(bcx, cond, |bcx|
2346 controlflow::trans_fail(bcx, info,
2347 InternedString::new("shift operation overflowed")));
2353 // Check if an integer or vector contains a nonzero element.
2354 fn build_nonzero_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2356 binop_debug_loc: DebugLoc) -> ValueRef {
2357 let llty = val_ty(value);
2358 let kind = llty.kind();
2360 TypeKind::Integer => ICmp(bcx, llvm::IntNE, value, C_null(llty), binop_debug_loc),
2361 TypeKind::Vector => {
2362 // Check if any elements of the vector are nonzero by treating
2363 // it as a wide integer and checking if the integer is nonzero.
2364 let width = llty.vector_length() as u64 * llty.element_type().int_width();
2365 let int_value = BitCast(bcx, value, Type::ix(bcx.ccx(), width));
2366 build_nonzero_check(bcx, int_value, binop_debug_loc)
2368 _ => panic!("build_nonzero_check: expected Integer or Vector, found {:?}", kind),
2372 fn with_overflow_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, oop: OverflowOp, info: NodeIdAndSpan,
2373 lhs_t: Ty<'tcx>, lhs: ValueRef,
2375 binop_debug_loc: DebugLoc)
2376 -> (Block<'blk, 'tcx>, ValueRef) {
2377 if bcx.unreachable.get() { return (bcx, _Undef(lhs)); }
2378 if bcx.ccx().check_overflow() {
2380 match oop.codegen_strategy() {
2381 OverflowCodegen::ViaIntrinsic(oop) =>
2382 oop.build_intrinsic_call(bcx, info, lhs_t, lhs, rhs, binop_debug_loc),
2383 OverflowCodegen::ViaInputCheck(oop) =>
2384 oop.build_with_input_check(bcx, info, lhs_t, lhs, rhs, binop_debug_loc),
2387 let res = match oop {
2388 OverflowOp::Add => Add(bcx, lhs, rhs, binop_debug_loc),
2389 OverflowOp::Sub => Sub(bcx, lhs, rhs, binop_debug_loc),
2390 OverflowOp::Mul => Mul(bcx, lhs, rhs, binop_debug_loc),
2393 build_unchecked_lshift(bcx, lhs, rhs, binop_debug_loc),
2395 build_unchecked_rshift(bcx, lhs_t, lhs, rhs, binop_debug_loc),
2401 /// We categorize expressions into three kinds. The distinction between
2402 /// lvalue/rvalue is fundamental to the language. The distinction between the
2403 /// two kinds of rvalues is an artifact of trans which reflects how we will
2404 /// generate code for that kind of expression. See trans/expr.rs for more
2406 #[derive(Copy, Clone)]
2414 fn expr_kind(tcx: &TyCtxt, expr: &hir::Expr) -> ExprKind {
2415 if tcx.is_method_call(expr.id) {
2416 // Overloaded operations are generally calls, and hence they are
2417 // generated via DPS, but there are a few exceptions:
2418 return match expr.node {
2419 // `a += b` has a unit result.
2420 hir::ExprAssignOp(..) => ExprKind::RvalueStmt,
2422 // the deref method invoked for `*a` always yields an `&T`
2423 hir::ExprUnary(hir::UnDeref, _) => ExprKind::Lvalue,
2425 // the index method invoked for `a[i]` always yields an `&T`
2426 hir::ExprIndex(..) => ExprKind::Lvalue,
2428 // in the general case, result could be any type, use DPS
2429 _ => ExprKind::RvalueDps
2434 hir::ExprPath(..) => {
2435 match tcx.resolve_expr(expr) {
2436 // Put functions and ctors with the ADTs, as they
2437 // are zero-sized, so DPS is the cheapest option.
2438 Def::Struct(..) | Def::Variant(..) |
2439 Def::Fn(..) | Def::Method(..) => {
2443 // Note: there is actually a good case to be made that
2444 // DefArg's, particularly those of immediate type, ought to
2445 // considered rvalues.
2448 Def::Local(..) => ExprKind::Lvalue,
2451 Def::AssociatedConst(..) => ExprKind::RvalueDatum,
2456 &format!("uncategorized def for expr {}: {:?}",
2463 hir::ExprType(ref expr, _) => {
2464 expr_kind(tcx, expr)
2467 hir::ExprUnary(hir::UnDeref, _) |
2468 hir::ExprField(..) |
2469 hir::ExprTupField(..) |
2470 hir::ExprIndex(..) => {
2475 hir::ExprMethodCall(..) |
2476 hir::ExprStruct(..) |
2479 hir::ExprMatch(..) |
2480 hir::ExprClosure(..) |
2481 hir::ExprBlock(..) |
2482 hir::ExprRepeat(..) |
2483 hir::ExprVec(..) => {
2487 hir::ExprLit(ref lit) if lit.node.is_str() => {
2491 hir::ExprBreak(..) |
2492 hir::ExprAgain(..) |
2494 hir::ExprWhile(..) |
2496 hir::ExprAssign(..) |
2497 hir::ExprInlineAsm(..) |
2498 hir::ExprAssignOp(..) => {
2499 ExprKind::RvalueStmt
2502 hir::ExprLit(_) | // Note: LitStr is carved out above
2503 hir::ExprUnary(..) |
2505 hir::ExprAddrOf(..) |
2506 hir::ExprBinary(..) |
2507 hir::ExprCast(..) => {
2508 ExprKind::RvalueDatum