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_var -> Datum`: looks up a local variable, upvar or static.
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};
72 use trans::value::Value;
74 use middle::ty::adjustment::{AdjustDerefRef, AdjustReifyFnPointer};
75 use middle::ty::adjustment::{AdjustUnsafeFnPointer, AdjustMutToConstPointer};
76 use middle::ty::adjustment::CustomCoerceUnsized;
77 use middle::ty::{self, Ty, TyCtxt};
78 use middle::ty::MethodCall;
79 use middle::ty::cast::{CastKind, CastTy};
80 use util::common::indenter;
81 use trans::machine::{llsize_of, llsize_of_alloc};
82 use trans::type_::Type;
87 use syntax::{ast, codemap};
88 use syntax::parse::token::InternedString;
94 // These are passed around by the code generating functions to track the
95 // destination of a computation's value.
97 #[derive(Copy, Clone, PartialEq)]
103 impl fmt::Debug for Dest {
104 fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
106 SaveIn(v) => write!(f, "SaveIn({:?})", Value(v)),
107 Ignore => f.write_str("Ignore")
112 /// This function is equivalent to `trans(bcx, expr).store_to_dest(dest)` but it may generate
113 /// better optimized LLVM code.
114 pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
117 -> Block<'blk, 'tcx> {
120 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
122 if adjustment_required(bcx, expr) {
123 // use trans, which may be less efficient but
124 // which will perform the adjustments:
125 let datum = unpack_datum!(bcx, trans(bcx, expr));
126 return datum.store_to_dest(bcx, dest, expr.id);
129 let qualif = *bcx.tcx().const_qualif_map.borrow().get(&expr.id).unwrap();
130 if !qualif.intersects(ConstQualif::NOT_CONST | ConstQualif::NEEDS_DROP) {
131 if !qualif.intersects(ConstQualif::PREFER_IN_PLACE) {
132 if let SaveIn(lldest) = dest {
133 match consts::get_const_expr_as_global(bcx.ccx(), expr, qualif,
134 bcx.fcx.param_substs,
135 consts::TrueConst::No) {
137 // Cast pointer to destination, because constants
138 // have different types.
139 let lldest = PointerCast(bcx, lldest, val_ty(global));
140 memcpy_ty(bcx, lldest, global, expr_ty_adjusted(bcx, expr));
143 Err(consts::ConstEvalFailure::Runtime(_)) => {
144 // in case const evaluation errors, translate normally
145 // debug assertions catch the same errors
148 Err(consts::ConstEvalFailure::Compiletime(_)) => {
154 // If we see a const here, that's because it evaluates to a type with zero size. We
155 // should be able to just discard it, since const expressions are guaranteed not to
156 // have side effects. This seems to be reached through tuple struct constructors being
157 // passed zero-size constants.
158 if let hir::ExprPath(..) = expr.node {
159 match bcx.def(expr.id) {
160 Def::Const(_) | Def::AssociatedConst(_) => {
161 assert!(type_is_zero_size(bcx.ccx(), bcx.tcx().node_id_to_type(expr.id)));
168 // Even if we don't have a value to emit, and the expression
169 // doesn't have any side-effects, we still have to translate the
170 // body of any closures.
171 // FIXME: Find a better way of handling this case.
173 // The only way we're going to see a `const` at this point is if
174 // it prefers in-place instantiation, likely because it contains
175 // `[x; N]` somewhere within.
177 hir::ExprPath(..) => {
178 match bcx.def(expr.id) {
179 Def::Const(did) | Def::AssociatedConst(did) => {
180 let empty_substs = bcx.tcx().mk_substs(Substs::trans_empty());
181 let const_expr = consts::get_const_expr(bcx.ccx(), did, expr,
183 // Temporarily get cleanup scopes out of the way,
184 // as they require sub-expressions to be contained
185 // inside the current AST scope.
186 // These should record no cleanups anyways, `const`
187 // can't have destructors.
188 let scopes = mem::replace(&mut *bcx.fcx.scopes.borrow_mut(),
190 // Lock emitted debug locations to the location of
191 // the constant reference expression.
192 debuginfo::with_source_location_override(bcx.fcx,
195 bcx = trans_into(bcx, const_expr, dest)
197 let scopes = mem::replace(&mut *bcx.fcx.scopes.borrow_mut(),
199 assert!(scopes.is_empty());
210 debug!("trans_into() expr={:?}", expr);
212 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
216 bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
218 let kind = expr_kind(bcx.tcx(), expr);
220 ExprKind::Lvalue | ExprKind::RvalueDatum => {
221 trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
223 ExprKind::RvalueDps => {
224 trans_rvalue_dps_unadjusted(bcx, expr, dest)
226 ExprKind::RvalueStmt => {
227 trans_rvalue_stmt_unadjusted(bcx, expr)
231 bcx.fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id)
234 /// Translates an expression, returning a datum (and new block) encapsulating the result. When
235 /// possible, it is preferred to use `trans_into`, as that may avoid creating a temporary on the
237 pub fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
239 -> DatumBlock<'blk, 'tcx, Expr> {
240 debug!("trans(expr={:?})", expr);
244 let qualif = *bcx.tcx().const_qualif_map.borrow().get(&expr.id).unwrap();
245 let adjusted_global = !qualif.intersects(ConstQualif::NON_STATIC_BORROWS);
246 let global = if !qualif.intersects(ConstQualif::NOT_CONST | ConstQualif::NEEDS_DROP) {
247 match consts::get_const_expr_as_global(bcx.ccx(), expr, qualif,
248 bcx.fcx.param_substs,
249 consts::TrueConst::No) {
251 if qualif.intersects(ConstQualif::HAS_STATIC_BORROWS) {
252 // Is borrowed as 'static, must return lvalue.
254 // Cast pointer to global, because constants have different types.
255 let const_ty = expr_ty_adjusted(bcx, expr);
256 let llty = type_of::type_of(bcx.ccx(), const_ty);
257 let global = PointerCast(bcx, global, llty.ptr_to());
258 let datum = Datum::new(global, const_ty, Lvalue::new("expr::trans"));
259 return DatumBlock::new(bcx, datum.to_expr_datum());
262 // Otherwise, keep around and perform adjustments, if needed.
263 let const_ty = if adjusted_global {
264 expr_ty_adjusted(bcx, expr)
269 // This could use a better heuristic.
270 Some(if type_is_immediate(bcx.ccx(), const_ty) {
271 // Cast pointer to global, because constants have different types.
272 let llty = type_of::type_of(bcx.ccx(), const_ty);
273 let global = PointerCast(bcx, global, llty.ptr_to());
274 // Maybe just get the value directly, instead of loading it?
275 immediate_rvalue(load_ty(bcx, global, const_ty), const_ty)
277 let scratch = alloc_ty(bcx, const_ty, "const");
278 call_lifetime_start(bcx, scratch);
279 let lldest = if !const_ty.is_structural() {
280 // Cast pointer to slot, because constants have different types.
281 PointerCast(bcx, scratch, val_ty(global))
283 // In this case, memcpy_ty calls llvm.memcpy after casting both
284 // source and destination to i8*, so we don't need any casts.
287 memcpy_ty(bcx, lldest, global, const_ty);
288 Datum::new(scratch, const_ty, Rvalue::new(ByRef))
291 Err(consts::ConstEvalFailure::Runtime(_)) => {
292 // in case const evaluation errors, translate normally
293 // debug assertions catch the same errors
297 Err(consts::ConstEvalFailure::Compiletime(_)) => {
298 // generate a dummy llvm value
299 let const_ty = expr_ty(bcx, expr);
300 let llty = type_of::type_of(bcx.ccx(), const_ty);
301 let dummy = C_undef(llty.ptr_to());
302 Some(Datum::new(dummy, const_ty, Rvalue::new(ByRef)))
309 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
313 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
314 let datum = match global {
315 Some(rvalue) => rvalue.to_expr_datum(),
316 None => unpack_datum!(bcx, trans_unadjusted(bcx, expr))
318 let datum = if adjusted_global {
319 datum // trans::consts already performed adjustments.
321 unpack_datum!(bcx, apply_adjustments(bcx, expr, datum))
323 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id);
324 return DatumBlock::new(bcx, datum);
327 pub fn get_meta(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
328 StructGEP(bcx, fat_ptr, abi::FAT_PTR_EXTRA)
331 pub fn get_dataptr(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
332 StructGEP(bcx, fat_ptr, abi::FAT_PTR_ADDR)
335 pub fn copy_fat_ptr(bcx: Block, src_ptr: ValueRef, dst_ptr: ValueRef) {
336 Store(bcx, Load(bcx, get_dataptr(bcx, src_ptr)), get_dataptr(bcx, dst_ptr));
337 Store(bcx, Load(bcx, get_meta(bcx, src_ptr)), get_meta(bcx, dst_ptr));
340 fn adjustment_required<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
341 expr: &hir::Expr) -> bool {
342 let adjustment = match bcx.tcx().tables.borrow().adjustments.get(&expr.id).cloned() {
343 None => { return false; }
347 // Don't skip a conversion from Box<T> to &T, etc.
348 if bcx.tcx().is_overloaded_autoderef(expr.id, 0) {
353 AdjustReifyFnPointer => true,
354 AdjustUnsafeFnPointer | AdjustMutToConstPointer => {
355 // purely a type-level thing
358 AdjustDerefRef(ref adj) => {
359 // We are a bit paranoid about adjustments and thus might have a re-
360 // borrow here which merely derefs and then refs again (it might have
361 // a different region or mutability, but we don't care here).
362 !(adj.autoderefs == 1 && adj.autoref.is_some() && adj.unsize.is_none())
367 /// Helper for trans that apply adjustments from `expr` to `datum`, which should be the unadjusted
368 /// translation of `expr`.
369 fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
371 datum: Datum<'tcx, Expr>)
372 -> DatumBlock<'blk, 'tcx, Expr>
375 let mut datum = datum;
376 let adjustment = match bcx.tcx().tables.borrow().adjustments.get(&expr.id).cloned() {
378 return DatumBlock::new(bcx, datum);
382 debug!("unadjusted datum for expr {:?}: {:?} adjustment={:?}",
383 expr, datum, adjustment);
385 AdjustReifyFnPointer => {
387 ty::TyFnDef(def_id, substs, _) => {
388 datum = Callee::def(bcx.ccx(), def_id, substs)
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);
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({:?} -> {:?})", source, target);
467 match (&source.ty.sty, &target.ty.sty) {
468 (&ty::TyBox(a), &ty::TyBox(b)) |
469 (&ty::TyRef(_, ty::TypeAndMut { ty: a, .. }),
470 &ty::TyRef(_, ty::TypeAndMut { ty: b, .. })) |
471 (&ty::TyRef(_, ty::TypeAndMut { ty: a, .. }),
472 &ty::TyRawPtr(ty::TypeAndMut { ty: b, .. })) |
473 (&ty::TyRawPtr(ty::TypeAndMut { ty: a, .. }),
474 &ty::TyRawPtr(ty::TypeAndMut { ty: b, .. })) => {
475 let (inner_source, inner_target) = (a, b);
477 let (base, old_info) = if !type_is_sized(bcx.tcx(), inner_source) {
478 // Normally, the source is a thin pointer and we are
479 // adding extra info to make a fat pointer. The exception
480 // is when we are upcasting an existing object fat pointer
481 // to use a different vtable. In that case, we want to
482 // load out the original data pointer so we can repackage
484 (Load(bcx, get_dataptr(bcx, source.val)),
485 Some(Load(bcx, get_meta(bcx, source.val))))
487 let val = if source.kind.is_by_ref() {
488 load_ty(bcx, source.val, source.ty)
495 let info = unsized_info(bcx.ccx(), inner_source, inner_target, old_info);
497 // Compute the base pointer. This doesn't change the pointer value,
498 // but merely its type.
499 let ptr_ty = type_of::in_memory_type_of(bcx.ccx(), inner_target).ptr_to();
500 let base = PointerCast(bcx, base, ptr_ty);
502 Store(bcx, base, get_dataptr(bcx, target.val));
503 Store(bcx, info, get_meta(bcx, target.val));
506 // This can be extended to enums and tuples in the future.
507 // (&ty::TyEnum(def_id_a, _), &ty::TyEnum(def_id_b, _)) |
508 (&ty::TyStruct(def_id_a, _), &ty::TyStruct(def_id_b, _)) => {
509 assert_eq!(def_id_a, def_id_b);
511 // The target is already by-ref because it's to be written to.
512 let source = unpack_datum!(bcx, source.to_ref_datum(bcx));
513 assert!(target.kind.is_by_ref());
515 let kind = custom_coerce_unsize_info(bcx.ccx(), source.ty, target.ty);
517 let repr_source = adt::represent_type(bcx.ccx(), source.ty);
518 let src_fields = match &*repr_source {
519 &adt::Repr::Univariant(ref s, _) => &s.fields,
520 _ => bcx.sess().span_bug(span,
521 &format!("Non univariant struct? (repr_source: {:?})",
524 let repr_target = adt::represent_type(bcx.ccx(), target.ty);
525 let target_fields = match &*repr_target {
526 &adt::Repr::Univariant(ref s, _) => &s.fields,
527 _ => bcx.sess().span_bug(span,
528 &format!("Non univariant struct? (repr_target: {:?})",
532 let coerce_index = match kind {
533 CustomCoerceUnsized::Struct(i) => i
535 assert!(coerce_index < src_fields.len() && src_fields.len() == target_fields.len());
537 let source_val = adt::MaybeSizedValue::sized(source.val);
538 let target_val = adt::MaybeSizedValue::sized(target.val);
540 let iter = src_fields.iter().zip(target_fields).enumerate();
541 for (i, (src_ty, target_ty)) in iter {
542 let ll_source = adt::trans_field_ptr(bcx, &repr_source, source_val, Disr(0), i);
543 let ll_target = adt::trans_field_ptr(bcx, &repr_target, target_val, Disr(0), i);
545 // If this is the field we need to coerce, recurse on it.
546 if i == coerce_index {
547 coerce_unsized(bcx, span,
548 Datum::new(ll_source, src_ty,
550 Datum::new(ll_target, target_ty,
551 Rvalue::new(ByRef)));
553 // Otherwise, simply copy the data from the source.
554 assert!(src_ty.is_phantom_data() || src_ty == target_ty);
555 memcpy_ty(bcx, ll_target, ll_source, src_ty);
559 _ => bcx.sess().bug(&format!("coerce_unsized: invalid coercion {:?} -> {:?}",
566 /// Translates an expression in "lvalue" mode -- meaning that it returns a reference to the memory
567 /// that the expr represents.
569 /// If this expression is an rvalue, this implies introducing a temporary. In other words,
570 /// something like `x().f` is translated into roughly the equivalent of
572 /// { tmp = x(); tmp.f }
573 pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
576 -> DatumBlock<'blk, 'tcx, Lvalue> {
578 let datum = unpack_datum!(bcx, trans(bcx, expr));
579 return datum.to_lvalue_datum(bcx, name, expr.id);
582 /// A version of `trans` that ignores adjustments. You almost certainly do not want to call this
584 fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
586 -> DatumBlock<'blk, 'tcx, Expr> {
589 debug!("trans_unadjusted(expr={:?})", expr);
590 let _indenter = indenter();
592 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
594 return match expr_kind(bcx.tcx(), expr) {
595 ExprKind::Lvalue | ExprKind::RvalueDatum => {
596 let datum = unpack_datum!(bcx, {
597 trans_datum_unadjusted(bcx, expr)
600 DatumBlock {bcx: bcx, datum: datum}
603 ExprKind::RvalueStmt => {
604 bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
605 nil(bcx, expr_ty(bcx, expr))
608 ExprKind::RvalueDps => {
609 let ty = expr_ty(bcx, expr);
610 if type_is_zero_size(bcx.ccx(), ty) {
611 bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
614 let scratch = rvalue_scratch_datum(bcx, ty, "");
615 bcx = trans_rvalue_dps_unadjusted(
616 bcx, expr, SaveIn(scratch.val));
618 // Note: this is not obviously a good idea. It causes
619 // immediate values to be loaded immediately after a
620 // return from a call or other similar expression,
621 // which in turn leads to alloca's having shorter
622 // lifetimes and hence larger stack frames. However,
623 // in turn it can lead to more register pressure.
624 // Still, in practice it seems to increase
625 // performance, since we have fewer problems with
627 let scratch = unpack_datum!(
628 bcx, scratch.to_appropriate_datum(bcx));
630 DatumBlock::new(bcx, scratch.to_expr_datum())
635 fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: Ty<'tcx>)
636 -> DatumBlock<'blk, 'tcx, Expr> {
637 let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
638 let datum = immediate_rvalue(llval, ty);
639 DatumBlock::new(bcx, datum.to_expr_datum())
643 fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
645 -> DatumBlock<'blk, 'tcx, Expr> {
648 let _icx = push_ctxt("trans_datum_unadjusted");
651 hir::ExprType(ref e, _) => {
654 hir::ExprPath(..) => {
655 let var = trans_var(bcx, bcx.def(expr.id));
656 DatumBlock::new(bcx, var.to_expr_datum())
658 hir::ExprField(ref base, name) => {
659 trans_rec_field(bcx, &base, name.node)
661 hir::ExprTupField(ref base, idx) => {
662 trans_rec_tup_field(bcx, &base, idx.node)
664 hir::ExprIndex(ref base, ref idx) => {
665 trans_index(bcx, expr, &base, &idx, MethodCall::expr(expr.id))
667 hir::ExprBox(ref contents) => {
668 // Special case for `Box<T>`
669 let box_ty = expr_ty(bcx, expr);
670 let contents_ty = expr_ty(bcx, &contents);
673 trans_uniq_expr(bcx, expr, box_ty, &contents, contents_ty)
675 _ => bcx.sess().span_bug(expr.span,
676 "expected unique box")
680 hir::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &lit),
681 hir::ExprBinary(op, ref lhs, ref rhs) => {
682 trans_binary(bcx, expr, op, &lhs, &rhs)
684 hir::ExprUnary(op, ref x) => {
685 trans_unary(bcx, expr, op, &x)
687 hir::ExprAddrOf(_, ref x) => {
689 hir::ExprRepeat(..) | hir::ExprVec(..) => {
690 // Special case for slices.
691 let cleanup_debug_loc =
692 debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
696 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
697 let datum = unpack_datum!(
698 bcx, tvec::trans_slice_vec(bcx, expr, &x));
699 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
700 DatumBlock::new(bcx, datum)
703 trans_addr_of(bcx, expr, &x)
707 hir::ExprCast(ref val, _) => {
708 // Datum output mode means this is a scalar cast:
709 trans_imm_cast(bcx, &val, expr.id)
712 bcx.tcx().sess.span_bug(
714 &format!("trans_rvalue_datum_unadjusted reached \
715 fall-through case: {:?}",
721 fn trans_field<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
724 -> DatumBlock<'blk, 'tcx, Expr> where
725 F: FnOnce(&'blk TyCtxt<'tcx>, &VariantInfo<'tcx>) -> usize,
728 let _icx = push_ctxt("trans_rec_field");
730 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
731 let bare_ty = base_datum.ty;
732 let repr = adt::represent_type(bcx.ccx(), bare_ty);
733 let vinfo = VariantInfo::from_ty(bcx.tcx(), bare_ty, None);
735 let ix = get_idx(bcx.tcx(), &vinfo);
736 let d = base_datum.get_element(
740 adt::trans_field_ptr(bcx, &repr, srcval, vinfo.discr, ix)
743 if type_is_sized(bcx.tcx(), d.ty) {
744 DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
746 let scratch = rvalue_scratch_datum(bcx, d.ty, "");
747 Store(bcx, d.val, get_dataptr(bcx, scratch.val));
748 let info = Load(bcx, get_meta(bcx, base_datum.val));
749 Store(bcx, info, get_meta(bcx, scratch.val));
751 // Always generate an lvalue datum, because this pointer doesn't own
752 // the data and cleanup is scheduled elsewhere.
753 DatumBlock::new(bcx, Datum::new(scratch.val, scratch.ty, LvalueExpr(d.kind)))
757 /// Translates `base.field`.
758 fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
761 -> DatumBlock<'blk, 'tcx, Expr> {
762 trans_field(bcx, base, |_, vinfo| vinfo.field_index(field))
765 /// Translates `base.<idx>`.
766 fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
769 -> DatumBlock<'blk, 'tcx, Expr> {
770 trans_field(bcx, base, |_, _| idx)
773 fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
774 index_expr: &hir::Expr,
777 method_call: MethodCall)
778 -> DatumBlock<'blk, 'tcx, Expr> {
779 //! Translates `base[idx]`.
781 let _icx = push_ctxt("trans_index");
785 let index_expr_debug_loc = index_expr.debug_loc();
787 // Check for overloaded index.
788 let method = ccx.tcx().tables.borrow().method_map.get(&method_call).cloned();
789 let elt_datum = match method {
791 let method_ty = monomorphize_type(bcx, method.ty);
793 let base_datum = unpack_datum!(bcx, trans(bcx, base));
795 // Translate index expression.
796 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
798 let ref_ty = // invoked methods have LB regions instantiated:
799 bcx.tcx().no_late_bound_regions(&method_ty.fn_ret()).unwrap().unwrap();
800 let elt_ty = match ref_ty.builtin_deref(true, ty::NoPreference) {
802 bcx.tcx().sess.span_bug(index_expr.span,
803 "index method didn't return a \
804 dereferenceable type?!")
806 Some(elt_tm) => elt_tm.ty,
809 // Overloaded. Invoke the index() method, which basically
810 // yields a `&T` pointer. We can then proceed down the
811 // normal path (below) to dereference that `&T`.
812 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_index_elt");
814 bcx = Callee::method(bcx, method)
815 .call(bcx, index_expr_debug_loc,
816 ArgOverloadedOp(base_datum, Some(ix_datum)),
817 Some(SaveIn(scratch.val))).bcx;
819 let datum = scratch.to_expr_datum();
820 let lval = Lvalue::new("expr::trans_index overload");
821 if type_is_sized(bcx.tcx(), elt_ty) {
822 Datum::new(datum.to_llscalarish(bcx), elt_ty, LvalueExpr(lval))
824 Datum::new(datum.val, elt_ty, LvalueExpr(lval))
828 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
832 // Translate index expression and cast to a suitable LLVM integer.
833 // Rust is less strict than LLVM in this regard.
834 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
835 let ix_val = ix_datum.to_llscalarish(bcx);
836 let ix_size = machine::llbitsize_of_real(bcx.ccx(),
838 let int_size = machine::llbitsize_of_real(bcx.ccx(),
841 if ix_size < int_size {
842 if expr_ty(bcx, idx).is_signed() {
843 SExt(bcx, ix_val, ccx.int_type())
844 } else { ZExt(bcx, ix_val, ccx.int_type()) }
845 } else if ix_size > int_size {
846 Trunc(bcx, ix_val, ccx.int_type())
852 let unit_ty = base_datum.ty.sequence_element_type(bcx.tcx());
854 let (base, len) = base_datum.get_vec_base_and_len(bcx);
856 debug!("trans_index: base {:?}", Value(base));
857 debug!("trans_index: len {:?}", Value(len));
859 let bounds_check = ICmp(bcx,
863 index_expr_debug_loc);
864 let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
865 let expected = Call(bcx,
867 &[bounds_check, C_bool(ccx, false)],
869 index_expr_debug_loc);
870 bcx = with_cond(bcx, expected, |bcx| {
871 controlflow::trans_fail_bounds_check(bcx,
872 expr_info(index_expr),
876 let elt = InBoundsGEP(bcx, base, &[ix_val]);
877 let elt = PointerCast(bcx, elt, type_of::type_of(ccx, unit_ty).ptr_to());
878 let lval = Lvalue::new("expr::trans_index fallback");
879 Datum::new(elt, unit_ty, LvalueExpr(lval))
883 DatumBlock::new(bcx, elt_datum)
886 /// Translates a reference to a variable.
887 pub fn trans_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, def: Def)
888 -> Datum<'tcx, Lvalue> {
891 Def::Static(did, _) => consts::get_static(bcx.ccx(), did),
892 Def::Upvar(_, nid, _, _) => {
893 // Can't move upvars, so this is never a ZeroMemLastUse.
894 let local_ty = node_id_type(bcx, nid);
895 let lval = Lvalue::new_with_hint("expr::trans_var (upvar)",
896 bcx, nid, HintKind::ZeroAndMaintain);
897 match bcx.fcx.llupvars.borrow().get(&nid) {
898 Some(&val) => Datum::new(val, local_ty, lval),
900 bcx.sess().bug(&format!(
901 "trans_var: no llval for upvar {} found",
906 Def::Local(_, nid) => {
907 let datum = match bcx.fcx.lllocals.borrow().get(&nid) {
910 bcx.sess().bug(&format!(
911 "trans_var: no datum for local/arg {} found",
915 debug!("take_local(nid={}, v={:?}, ty={})",
916 nid, Value(datum.val), datum.ty);
919 _ => unreachable!("{:?} should not reach expr::trans_var", def)
923 fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
925 -> Block<'blk, 'tcx> {
927 let _icx = push_ctxt("trans_rvalue_stmt");
929 if bcx.unreachable.get() {
933 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
936 hir::ExprBreak(label_opt) => {
937 controlflow::trans_break(bcx, expr, label_opt.map(|l| l.node.name))
939 hir::ExprType(ref e, _) => {
940 trans_into(bcx, &e, Ignore)
942 hir::ExprAgain(label_opt) => {
943 controlflow::trans_cont(bcx, expr, label_opt.map(|l| l.node.name))
945 hir::ExprRet(ref ex) => {
946 // Check to see if the return expression itself is reachable.
947 // This can occur when the inner expression contains a return
948 let reachable = if let Some(ref cfg) = bcx.fcx.cfg {
949 cfg.node_is_reachable(expr.id)
955 controlflow::trans_ret(bcx, expr, ex.as_ref().map(|e| &**e))
957 // If it's not reachable, just translate the inner expression
958 // directly. This avoids having to manage a return slot when
959 // it won't actually be used anyway.
960 if let &Some(ref x) = ex {
961 bcx = trans_into(bcx, &x, Ignore);
963 // Mark the end of the block as unreachable. Once we get to
964 // a return expression, there's no more we should be doing
970 hir::ExprWhile(ref cond, ref body, _) => {
971 controlflow::trans_while(bcx, expr, &cond, &body)
973 hir::ExprLoop(ref body, _) => {
974 controlflow::trans_loop(bcx, expr, &body)
976 hir::ExprAssign(ref dst, ref src) => {
977 let src_datum = unpack_datum!(bcx, trans(bcx, &src));
978 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &dst, "assign"));
980 if bcx.fcx.type_needs_drop(dst_datum.ty) {
981 // If there are destructors involved, make sure we
982 // are copying from an rvalue, since that cannot possible
983 // alias an lvalue. We are concerned about code like:
991 // where e.g. a : Option<Foo> and a.b :
992 // Option<Foo>. In that case, freeing `a` before the
993 // assignment may also free `a.b`!
995 // We could avoid this intermediary with some analysis
996 // to determine whether `dst` may possibly own `src`.
997 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
998 let src_datum = unpack_datum!(
999 bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
1000 let opt_hint_datum = dst_datum.kind.drop_flag_info.hint_datum(bcx);
1001 let opt_hint_val = opt_hint_datum.map(|d|d.to_value());
1003 // 1. Drop the data at the destination, passing the
1004 // drop-hint in case the lvalue has already been
1005 // dropped or moved.
1006 bcx = glue::drop_ty_core(bcx,
1013 // 2. We are overwriting the destination; ensure that
1014 // its drop-hint (if any) says "initialized."
1015 if let Some(hint_val) = opt_hint_val {
1016 let hint_llval = hint_val.value();
1017 let drop_needed = C_u8(bcx.fcx.ccx, adt::DTOR_NEEDED_HINT);
1018 Store(bcx, drop_needed, hint_llval);
1020 src_datum.store_to(bcx, dst_datum.val)
1022 src_datum.store_to(bcx, dst_datum.val)
1025 hir::ExprAssignOp(op, ref dst, ref src) => {
1026 let method = bcx.tcx().tables
1029 .get(&MethodCall::expr(expr.id)).cloned();
1031 if let Some(method) = method {
1032 let dst = unpack_datum!(bcx, trans(bcx, &dst));
1033 let src_datum = unpack_datum!(bcx, trans(bcx, &src));
1035 Callee::method(bcx, method)
1036 .call(bcx, expr.debug_loc(),
1037 ArgOverloadedOp(dst, Some(src_datum)), None).bcx
1039 trans_assign_op(bcx, expr, op, &dst, &src)
1042 hir::ExprInlineAsm(ref a) => {
1043 asm::trans_inline_asm(bcx, a)
1046 bcx.tcx().sess.span_bug(
1048 &format!("trans_rvalue_stmt_unadjusted reached \
1049 fall-through case: {:?}",
1055 fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1058 -> Block<'blk, 'tcx> {
1059 let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
1062 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
1064 // Entry into the method table if this is an overloaded call/op.
1065 let method_call = MethodCall::expr(expr.id);
1068 hir::ExprType(ref e, _) => {
1069 trans_into(bcx, &e, dest)
1071 hir::ExprPath(..) => {
1072 trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
1074 hir::ExprIf(ref cond, ref thn, ref els) => {
1075 controlflow::trans_if(bcx, expr.id, &cond, &thn, els.as_ref().map(|e| &**e), dest)
1077 hir::ExprMatch(ref discr, ref arms, _) => {
1078 _match::trans_match(bcx, expr, &discr, &arms[..], dest)
1080 hir::ExprBlock(ref blk) => {
1081 controlflow::trans_block(bcx, &blk, dest)
1083 hir::ExprStruct(_, ref fields, ref base) => {
1086 base.as_ref().map(|e| &**e),
1089 node_id_type(bcx, expr.id),
1092 hir::ExprTup(ref args) => {
1093 let numbered_fields: Vec<(usize, &hir::Expr)> =
1094 args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
1098 &numbered_fields[..],
1103 hir::ExprLit(ref lit) => {
1105 ast::LitKind::Str(ref s, _) => {
1106 tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
1111 .span_bug(expr.span,
1112 "trans_rvalue_dps_unadjusted shouldn't be \
1113 translating this type of literal")
1117 hir::ExprVec(..) | hir::ExprRepeat(..) => {
1118 tvec::trans_fixed_vstore(bcx, expr, dest)
1120 hir::ExprClosure(_, ref decl, ref body) => {
1121 let dest = match dest {
1122 SaveIn(lldest) => closure::Dest::SaveIn(bcx, lldest),
1123 Ignore => closure::Dest::Ignore(bcx.ccx())
1126 // NB. To get the id of the closure, we don't use
1127 // `local_def_id(id)`, but rather we extract the closure
1128 // def-id from the expr's type. This is because this may
1129 // be an inlined expression from another crate, and we
1130 // want to get the ORIGINAL closure def-id, since that is
1131 // the key we need to find the closure-kind and
1132 // closure-type etc.
1133 let (def_id, substs) = match expr_ty(bcx, expr).sty {
1134 ty::TyClosure(def_id, ref substs) => (def_id, substs),
1136 bcx.tcx().sess.span_bug(
1138 &format!("closure expr without closure type: {:?}", t)),
1141 closure::trans_closure_expr(dest,
1147 &expr.attrs).unwrap_or(bcx)
1149 hir::ExprCall(ref f, ref args) => {
1150 let method = bcx.tcx().tables.borrow().method_map.get(&method_call).cloned();
1151 let (callee, args) = if let Some(method) = method {
1152 let mut all_args = vec![&**f];
1153 all_args.extend(args.iter().map(|e| &**e));
1155 (Callee::method(bcx, method), ArgOverloadedCall(all_args))
1157 let f = unpack_datum!(bcx, trans(bcx, f));
1159 ty::TyFnDef(def_id, substs, _) => {
1160 Callee::def(bcx.ccx(), def_id, substs)
1163 let f = unpack_datum!(bcx,
1164 f.to_rvalue_datum(bcx, "callee"));
1168 bcx.tcx().sess.span_bug(expr.span,
1169 &format!("type of callee is not a fn: {}", f.ty));
1173 callee.call(bcx, expr.debug_loc(), args, Some(dest)).bcx
1175 hir::ExprMethodCall(_, _, ref args) => {
1176 Callee::method_call(bcx, method_call)
1177 .call(bcx, expr.debug_loc(), ArgExprs(&args), Some(dest)).bcx
1179 hir::ExprBinary(op, ref lhs, ref rhs_expr) => {
1180 // if not overloaded, would be RvalueDatumExpr
1181 let lhs = unpack_datum!(bcx, trans(bcx, &lhs));
1182 let mut rhs = unpack_datum!(bcx, trans(bcx, &rhs_expr));
1183 if !rustc_front::util::is_by_value_binop(op.node) {
1184 rhs = unpack_datum!(bcx, auto_ref(bcx, rhs, rhs_expr));
1187 Callee::method_call(bcx, method_call)
1188 .call(bcx, expr.debug_loc(),
1189 ArgOverloadedOp(lhs, Some(rhs)), Some(dest)).bcx
1191 hir::ExprUnary(_, ref subexpr) => {
1192 // if not overloaded, would be RvalueDatumExpr
1193 let arg = unpack_datum!(bcx, trans(bcx, &subexpr));
1195 Callee::method_call(bcx, method_call)
1196 .call(bcx, expr.debug_loc(),
1197 ArgOverloadedOp(arg, None), Some(dest)).bcx
1199 hir::ExprCast(..) => {
1200 // Trait casts used to come this way, now they should be coercions.
1201 bcx.tcx().sess.span_bug(expr.span, "DPS expr_cast (residual trait cast?)")
1203 hir::ExprAssignOp(op, _, _) => {
1204 bcx.tcx().sess.span_bug(
1206 &format!("augmented assignment `{}=` should always be a rvalue_stmt",
1207 rustc_front::util::binop_to_string(op.node)))
1210 bcx.tcx().sess.span_bug(
1212 &format!("trans_rvalue_dps_unadjusted reached fall-through \
1219 fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1220 ref_expr: &hir::Expr,
1223 -> Block<'blk, 'tcx> {
1224 let _icx = push_ctxt("trans_def_dps_unadjusted");
1226 let lldest = match dest {
1227 SaveIn(lldest) => lldest,
1228 Ignore => { return bcx; }
1231 let ty = expr_ty(bcx, ref_expr);
1232 if let ty::TyFnDef(..) = ty.sty {
1233 // Zero-sized function or ctor.
1238 Def::Variant(tid, vid) => {
1239 let variant = bcx.tcx().lookup_adt_def(tid).variant_with_id(vid);
1241 let ty = expr_ty(bcx, ref_expr);
1242 let repr = adt::represent_type(bcx.ccx(), ty);
1243 adt::trans_set_discr(bcx, &repr, lldest, Disr::from(variant.disr_val));
1246 Def::Struct(..) => {
1248 ty::TyStruct(def, _) if def.has_dtor() => {
1249 let repr = adt::represent_type(bcx.ccx(), ty);
1250 adt::trans_set_discr(bcx, &repr, lldest, Disr(0));
1257 bcx.tcx().sess.span_bug(ref_expr.span, &format!(
1258 "Non-DPS def {:?} referened by {}",
1259 def, bcx.node_id_to_string(ref_expr.id)));
1264 fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1265 fields: &[hir::Field],
1266 base: Option<&hir::Expr>,
1267 expr_span: codemap::Span,
1268 expr_id: ast::NodeId,
1270 dest: Dest) -> Block<'blk, 'tcx> {
1271 let _icx = push_ctxt("trans_rec");
1273 let tcx = bcx.tcx();
1274 let vinfo = VariantInfo::of_node(tcx, ty, expr_id);
1276 let mut need_base = vec![true; vinfo.fields.len()];
1278 let numbered_fields = fields.iter().map(|field| {
1279 let pos = vinfo.field_index(field.name.node);
1280 need_base[pos] = false;
1282 }).collect::<Vec<_>>();
1284 let optbase = match base {
1285 Some(base_expr) => {
1286 let mut leftovers = Vec::new();
1287 for (i, b) in need_base.iter().enumerate() {
1289 leftovers.push((i, vinfo.fields[i].1));
1292 Some(StructBaseInfo {expr: base_expr,
1293 fields: leftovers })
1296 if need_base.iter().any(|b| *b) {
1297 tcx.sess.span_bug(expr_span, "missing fields and no base expr")
1309 DebugLoc::At(expr_id, expr_span))
1312 /// Information that `trans_adt` needs in order to fill in the fields
1313 /// of a struct copied from a base struct (e.g., from an expression
1314 /// like `Foo { a: b, ..base }`.
1316 /// Note that `fields` may be empty; the base expression must always be
1317 /// evaluated for side-effects.
1318 pub struct StructBaseInfo<'a, 'tcx> {
1319 /// The base expression; will be evaluated after all explicit fields.
1320 expr: &'a hir::Expr,
1321 /// The indices of fields to copy paired with their types.
1322 fields: Vec<(usize, Ty<'tcx>)>
1325 /// Constructs an ADT instance:
1327 /// - `fields` should be a list of field indices paired with the
1328 /// expression to store into that field. The initializers will be
1329 /// evaluated in the order specified by `fields`.
1331 /// - `optbase` contains information on the base struct (if any) from
1332 /// which remaining fields are copied; see comments on `StructBaseInfo`.
1333 pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1336 fields: &[(usize, &hir::Expr)],
1337 optbase: Option<StructBaseInfo<'a, 'tcx>>,
1339 debug_location: DebugLoc)
1340 -> Block<'blk, 'tcx> {
1341 let _icx = push_ctxt("trans_adt");
1343 let repr = adt::represent_type(bcx.ccx(), ty);
1345 debug_location.apply(bcx.fcx);
1347 // If we don't care about the result, just make a
1348 // temporary stack slot
1349 let addr = match dest {
1352 let llresult = alloc_ty(bcx, ty, "temp");
1353 call_lifetime_start(bcx, llresult);
1358 debug!("trans_adt");
1360 // This scope holds intermediates that must be cleaned should
1361 // panic occur before the ADT as a whole is ready.
1362 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1365 // Issue 23112: The original logic appeared vulnerable to same
1366 // order-of-eval bug. But, SIMD values are tuple-structs;
1367 // i.e. functional record update (FRU) syntax is unavailable.
1369 // To be safe, double-check that we did not get here via FRU.
1370 assert!(optbase.is_none());
1372 // This is the constructor of a SIMD type, such types are
1373 // always primitive machine types and so do not have a
1374 // destructor or require any clean-up.
1375 let llty = type_of::type_of(bcx.ccx(), ty);
1377 // keep a vector as a register, and running through the field
1378 // `insertelement`ing them directly into that register
1379 // (i.e. avoid GEPi and `store`s to an alloca) .
1380 let mut vec_val = C_undef(llty);
1382 for &(i, ref e) in fields {
1383 let block_datum = trans(bcx, &e);
1384 bcx = block_datum.bcx;
1385 let position = C_uint(bcx.ccx(), i);
1386 let value = block_datum.datum.to_llscalarish(bcx);
1387 vec_val = InsertElement(bcx, vec_val, value, position);
1389 Store(bcx, vec_val, addr);
1390 } else if let Some(base) = optbase {
1391 // Issue 23112: If there is a base, then order-of-eval
1392 // requires field expressions eval'ed before base expression.
1394 // First, trans field expressions to temporary scratch values.
1395 let scratch_vals: Vec<_> = fields.iter().map(|&(i, ref e)| {
1396 let datum = unpack_datum!(bcx, trans(bcx, &e));
1400 debug_location.apply(bcx.fcx);
1402 // Second, trans the base to the dest.
1403 assert_eq!(discr, Disr(0));
1405 let addr = adt::MaybeSizedValue::sized(addr);
1406 match expr_kind(bcx.tcx(), &base.expr) {
1407 ExprKind::RvalueDps | ExprKind::RvalueDatum if !bcx.fcx.type_needs_drop(ty) => {
1408 bcx = trans_into(bcx, &base.expr, SaveIn(addr.value));
1410 ExprKind::RvalueStmt => {
1411 bcx.tcx().sess.bug("unexpected expr kind for struct base expr")
1414 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &base.expr, "base"));
1415 for &(i, t) in &base.fields {
1416 let datum = base_datum.get_element(
1417 bcx, t, |srcval| adt::trans_field_ptr(bcx, &repr, srcval, discr, i));
1418 assert!(type_is_sized(bcx.tcx(), datum.ty));
1419 let dest = adt::trans_field_ptr(bcx, &repr, addr, discr, i);
1420 bcx = datum.store_to(bcx, dest);
1425 // Finally, move scratch field values into actual field locations
1426 for (i, datum) in scratch_vals {
1427 let dest = adt::trans_field_ptr(bcx, &repr, addr, discr, i);
1428 bcx = datum.store_to(bcx, dest);
1431 // No base means we can write all fields directly in place.
1432 let addr = adt::MaybeSizedValue::sized(addr);
1433 for &(i, ref e) in fields {
1434 let dest = adt::trans_field_ptr(bcx, &repr, addr, discr, i);
1435 let e_ty = expr_ty_adjusted(bcx, &e);
1436 bcx = trans_into(bcx, &e, SaveIn(dest));
1437 let scope = cleanup::CustomScope(custom_cleanup_scope);
1438 fcx.schedule_lifetime_end(scope, dest);
1439 // FIXME: nonzeroing move should generalize to fields
1440 fcx.schedule_drop_mem(scope, dest, e_ty, None);
1444 adt::trans_set_discr(bcx, &repr, addr, discr);
1446 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1448 // If we don't care about the result drop the temporary we made
1452 bcx = glue::drop_ty(bcx, addr, ty, debug_location);
1453 base::call_lifetime_end(bcx, addr);
1460 fn trans_immediate_lit<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1463 -> DatumBlock<'blk, 'tcx, Expr> {
1464 // must not be a string constant, that is a RvalueDpsExpr
1465 let _icx = push_ctxt("trans_immediate_lit");
1466 let ty = expr_ty(bcx, expr);
1467 let v = consts::const_lit(bcx.ccx(), expr, lit);
1468 immediate_rvalue_bcx(bcx, v, ty).to_expr_datumblock()
1471 fn trans_unary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1474 sub_expr: &hir::Expr)
1475 -> DatumBlock<'blk, 'tcx, Expr> {
1476 let ccx = bcx.ccx();
1478 let _icx = push_ctxt("trans_unary_datum");
1480 let method_call = MethodCall::expr(expr.id);
1482 // The only overloaded operator that is translated to a datum
1483 // is an overloaded deref, since it is always yields a `&T`.
1484 // Otherwise, we should be in the RvalueDpsExpr path.
1485 assert!(op == hir::UnDeref || !ccx.tcx().is_method_call(expr.id));
1487 let un_ty = expr_ty(bcx, expr);
1489 let debug_loc = expr.debug_loc();
1493 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1494 let llresult = Not(bcx, datum.to_llscalarish(bcx), debug_loc);
1495 immediate_rvalue_bcx(bcx, llresult, un_ty).to_expr_datumblock()
1498 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1499 let val = datum.to_llscalarish(bcx);
1500 let (bcx, llneg) = {
1502 let result = FNeg(bcx, val, debug_loc);
1505 let is_signed = un_ty.is_signed();
1506 let result = Neg(bcx, val, debug_loc);
1507 let bcx = if bcx.ccx().check_overflow() && is_signed {
1508 let (llty, min) = base::llty_and_min_for_signed_ty(bcx, un_ty);
1509 let is_min = ICmp(bcx, llvm::IntEQ, val,
1510 C_integral(llty, min, true), debug_loc);
1511 with_cond(bcx, is_min, |bcx| {
1512 let msg = InternedString::new(
1513 "attempted to negate with overflow");
1514 controlflow::trans_fail(bcx, expr_info(expr), msg)
1522 immediate_rvalue_bcx(bcx, llneg, un_ty).to_expr_datumblock()
1525 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1526 deref_once(bcx, expr, datum, method_call)
1531 fn trans_uniq_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1532 box_expr: &hir::Expr,
1534 contents: &hir::Expr,
1535 contents_ty: Ty<'tcx>)
1536 -> DatumBlock<'blk, 'tcx, Expr> {
1537 let _icx = push_ctxt("trans_uniq_expr");
1539 assert!(type_is_sized(bcx.tcx(), contents_ty));
1540 let llty = type_of::type_of(bcx.ccx(), contents_ty);
1541 let size = llsize_of(bcx.ccx(), llty);
1542 let align = C_uint(bcx.ccx(), type_of::align_of(bcx.ccx(), contents_ty));
1543 let llty_ptr = llty.ptr_to();
1544 let Result { bcx, val } = malloc_raw_dyn(bcx,
1549 box_expr.debug_loc());
1550 // Unique boxes do not allocate for zero-size types. The standard library
1551 // may assume that `free` is never called on the pointer returned for
1552 // `Box<ZeroSizeType>`.
1553 let bcx = if llsize_of_alloc(bcx.ccx(), llty) == 0 {
1554 trans_into(bcx, contents, SaveIn(val))
1556 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1557 fcx.schedule_free_value(cleanup::CustomScope(custom_cleanup_scope),
1558 val, cleanup::HeapExchange, contents_ty);
1559 let bcx = trans_into(bcx, contents, SaveIn(val));
1560 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1563 immediate_rvalue_bcx(bcx, val, box_ty).to_expr_datumblock()
1566 fn trans_addr_of<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1568 subexpr: &hir::Expr)
1569 -> DatumBlock<'blk, 'tcx, Expr> {
1570 let _icx = push_ctxt("trans_addr_of");
1572 let sub_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, subexpr, "addr_of"));
1573 let ty = expr_ty(bcx, expr);
1574 if !type_is_sized(bcx.tcx(), sub_datum.ty) {
1575 // Always generate an lvalue datum, because this pointer doesn't own
1576 // the data and cleanup is scheduled elsewhere.
1577 DatumBlock::new(bcx, Datum::new(sub_datum.val, ty, LvalueExpr(sub_datum.kind)))
1579 // Sized value, ref to a thin pointer
1580 immediate_rvalue_bcx(bcx, sub_datum.val, ty).to_expr_datumblock()
1584 fn trans_scalar_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1585 binop_expr: &hir::Expr,
1588 lhs: Datum<'tcx, Rvalue>,
1589 rhs: Datum<'tcx, Rvalue>)
1590 -> DatumBlock<'blk, 'tcx, Expr>
1592 let _icx = push_ctxt("trans_scalar_binop");
1594 let tcx = bcx.tcx();
1596 assert!(!lhs_t.is_simd());
1597 let is_float = lhs_t.is_fp();
1598 let is_signed = lhs_t.is_signed();
1599 let info = expr_info(binop_expr);
1601 let binop_debug_loc = binop_expr.debug_loc();
1604 let lhs = lhs.to_llscalarish(bcx);
1605 let rhs = rhs.to_llscalarish(bcx);
1606 let val = match op.node {
1609 FAdd(bcx, lhs, rhs, binop_debug_loc)
1611 let (newbcx, res) = with_overflow_check(
1612 bcx, OverflowOp::Add, info, lhs_t, lhs, rhs, binop_debug_loc);
1619 FSub(bcx, lhs, rhs, binop_debug_loc)
1621 let (newbcx, res) = with_overflow_check(
1622 bcx, OverflowOp::Sub, info, lhs_t, lhs, rhs, binop_debug_loc);
1629 FMul(bcx, lhs, rhs, binop_debug_loc)
1631 let (newbcx, res) = with_overflow_check(
1632 bcx, OverflowOp::Mul, info, lhs_t, lhs, rhs, binop_debug_loc);
1639 FDiv(bcx, lhs, rhs, binop_debug_loc)
1641 // Only zero-check integers; fp /0 is NaN
1642 bcx = base::fail_if_zero_or_overflows(bcx,
1643 expr_info(binop_expr),
1649 SDiv(bcx, lhs, rhs, binop_debug_loc)
1651 UDiv(bcx, lhs, rhs, binop_debug_loc)
1657 // LLVM currently always lowers the `frem` instructions appropriate
1658 // library calls typically found in libm. Notably f64 gets wired up
1659 // to `fmod` and f32 gets wired up to `fmodf`. Inconveniently for
1660 // us, 32-bit MSVC does not actually have a `fmodf` symbol, it's
1661 // instead just an inline function in a header that goes up to a
1662 // f64, uses `fmod`, and then comes back down to a f32.
1664 // Although LLVM knows that `fmodf` doesn't exist on MSVC, it will
1665 // still unconditionally lower frem instructions over 32-bit floats
1666 // to a call to `fmodf`. To work around this we special case MSVC
1667 // 32-bit float rem instructions and instead do the call out to
1668 // `fmod` ourselves.
1670 // Note that this is currently duplicated with src/libcore/ops.rs
1671 // which does the same thing, and it would be nice to perhaps unify
1672 // these two implementations on day! Also note that we call `fmod`
1673 // for both 32 and 64-bit floats because if we emit any FRem
1674 // instruction at all then LLVM is capable of optimizing it into a
1675 // 32-bit FRem (which we're trying to avoid).
1676 let use_fmod = tcx.sess.target.target.options.is_like_msvc &&
1677 tcx.sess.target.target.arch == "x86";
1679 let f64t = Type::f64(bcx.ccx());
1680 let fty = Type::func(&[f64t, f64t], &f64t);
1681 let llfn = declare::declare_cfn(bcx.ccx(), "fmod", fty,
1683 if lhs_t == tcx.types.f32 {
1684 let lhs = FPExt(bcx, lhs, f64t);
1685 let rhs = FPExt(bcx, rhs, f64t);
1686 let res = Call(bcx, llfn, &[lhs, rhs], None, binop_debug_loc);
1687 FPTrunc(bcx, res, Type::f32(bcx.ccx()))
1689 Call(bcx, llfn, &[lhs, rhs], None, binop_debug_loc)
1692 FRem(bcx, lhs, rhs, binop_debug_loc)
1695 // Only zero-check integers; fp %0 is NaN
1696 bcx = base::fail_if_zero_or_overflows(bcx,
1697 expr_info(binop_expr),
1698 op, lhs, rhs, lhs_t);
1700 SRem(bcx, lhs, rhs, binop_debug_loc)
1702 URem(bcx, lhs, rhs, binop_debug_loc)
1706 hir::BiBitOr => Or(bcx, lhs, rhs, binop_debug_loc),
1707 hir::BiBitAnd => And(bcx, lhs, rhs, binop_debug_loc),
1708 hir::BiBitXor => Xor(bcx, lhs, rhs, binop_debug_loc),
1710 let (newbcx, res) = with_overflow_check(
1711 bcx, OverflowOp::Shl, info, lhs_t, lhs, rhs, binop_debug_loc);
1716 let (newbcx, res) = with_overflow_check(
1717 bcx, OverflowOp::Shr, info, lhs_t, lhs, rhs, binop_debug_loc);
1721 hir::BiEq | hir::BiNe | hir::BiLt | hir::BiGe | hir::BiLe | hir::BiGt => {
1722 base::compare_scalar_types(bcx, lhs, rhs, lhs_t, op.node, binop_debug_loc)
1725 bcx.tcx().sess.span_bug(binop_expr.span, "unexpected binop");
1729 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1732 // refinement types would obviate the need for this
1733 enum lazy_binop_ty {
1738 fn trans_lazy_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1739 binop_expr: &hir::Expr,
1743 -> DatumBlock<'blk, 'tcx, Expr> {
1744 let _icx = push_ctxt("trans_lazy_binop");
1745 let binop_ty = expr_ty(bcx, binop_expr);
1748 let DatumBlock {bcx: past_lhs, datum: lhs} = trans(bcx, a);
1749 let lhs = lhs.to_llscalarish(past_lhs);
1751 if past_lhs.unreachable.get() {
1752 return immediate_rvalue_bcx(past_lhs, lhs, binop_ty).to_expr_datumblock();
1755 let join = fcx.new_id_block("join", binop_expr.id);
1756 let before_rhs = fcx.new_id_block("before_rhs", b.id);
1759 lazy_and => CondBr(past_lhs, lhs, before_rhs.llbb, join.llbb, DebugLoc::None),
1760 lazy_or => CondBr(past_lhs, lhs, join.llbb, before_rhs.llbb, DebugLoc::None)
1763 let DatumBlock {bcx: past_rhs, datum: rhs} = trans(before_rhs, b);
1764 let rhs = rhs.to_llscalarish(past_rhs);
1766 if past_rhs.unreachable.get() {
1767 return immediate_rvalue_bcx(join, lhs, binop_ty).to_expr_datumblock();
1770 Br(past_rhs, join.llbb, DebugLoc::None);
1771 let phi = Phi(join, Type::i1(bcx.ccx()), &[lhs, rhs],
1772 &[past_lhs.llbb, past_rhs.llbb]);
1774 return immediate_rvalue_bcx(join, phi, binop_ty).to_expr_datumblock();
1777 fn trans_binary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1782 -> DatumBlock<'blk, 'tcx, Expr> {
1783 let _icx = push_ctxt("trans_binary");
1784 let ccx = bcx.ccx();
1786 // if overloaded, would be RvalueDpsExpr
1787 assert!(!ccx.tcx().is_method_call(expr.id));
1791 trans_lazy_binop(bcx, expr, lazy_and, lhs, rhs)
1794 trans_lazy_binop(bcx, expr, lazy_or, lhs, rhs)
1798 let binop_ty = expr_ty(bcx, expr);
1800 let lhs = unpack_datum!(bcx, trans(bcx, lhs));
1801 let lhs = unpack_datum!(bcx, lhs.to_rvalue_datum(bcx, "binop_lhs"));
1802 debug!("trans_binary (expr {}): lhs={:?}", expr.id, lhs);
1803 let rhs = unpack_datum!(bcx, trans(bcx, rhs));
1804 let rhs = unpack_datum!(bcx, rhs.to_rvalue_datum(bcx, "binop_rhs"));
1805 debug!("trans_binary (expr {}): rhs={:?}", expr.id, rhs);
1807 if type_is_fat_ptr(ccx.tcx(), lhs.ty) {
1808 assert!(type_is_fat_ptr(ccx.tcx(), rhs.ty),
1809 "built-in binary operators on fat pointers are homogeneous");
1810 assert_eq!(binop_ty, bcx.tcx().types.bool);
1811 let val = base::compare_scalar_types(
1818 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1820 assert!(!type_is_fat_ptr(ccx.tcx(), rhs.ty),
1821 "built-in binary operators on fat pointers are homogeneous");
1822 trans_scalar_binop(bcx, expr, binop_ty, op, lhs, rhs)
1828 pub fn cast_is_noop<'tcx>(tcx: &TyCtxt<'tcx>,
1833 if let Some(&CastKind::CoercionCast) = tcx.cast_kinds.borrow().get(&expr.id) {
1837 match (t_in.builtin_deref(true, ty::NoPreference),
1838 t_out.builtin_deref(true, ty::NoPreference)) {
1839 (Some(ty::TypeAndMut{ ty: t_in, .. }), Some(ty::TypeAndMut{ ty: t_out, .. })) => {
1843 // This condition isn't redundant with the check for CoercionCast:
1844 // different types can be substituted into the same type, and
1845 // == equality can be overconservative if there are regions.
1851 fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1854 -> DatumBlock<'blk, 'tcx, Expr>
1856 use middle::ty::cast::CastTy::*;
1857 use middle::ty::cast::IntTy::*;
1859 fn int_cast(bcx: Block,
1866 let _icx = push_ctxt("int_cast");
1867 let srcsz = llsrctype.int_width();
1868 let dstsz = lldsttype.int_width();
1869 return if dstsz == srcsz {
1870 BitCast(bcx, llsrc, lldsttype)
1871 } else if srcsz > dstsz {
1872 TruncOrBitCast(bcx, llsrc, lldsttype)
1874 SExtOrBitCast(bcx, llsrc, lldsttype)
1876 ZExtOrBitCast(bcx, llsrc, lldsttype)
1880 fn float_cast(bcx: Block,
1886 let _icx = push_ctxt("float_cast");
1887 let srcsz = llsrctype.float_width();
1888 let dstsz = lldsttype.float_width();
1889 return if dstsz > srcsz {
1890 FPExt(bcx, llsrc, lldsttype)
1891 } else if srcsz > dstsz {
1892 FPTrunc(bcx, llsrc, lldsttype)
1896 let _icx = push_ctxt("trans_cast");
1898 let ccx = bcx.ccx();
1900 let t_in = expr_ty_adjusted(bcx, expr);
1901 let t_out = node_id_type(bcx, id);
1903 debug!("trans_cast({:?} as {:?})", t_in, t_out);
1904 let mut ll_t_in = type_of::arg_type_of(ccx, t_in);
1905 let ll_t_out = type_of::arg_type_of(ccx, t_out);
1906 // Convert the value to be cast into a ValueRef, either by-ref or
1907 // by-value as appropriate given its type:
1908 let mut datum = unpack_datum!(bcx, trans(bcx, expr));
1910 let datum_ty = monomorphize_type(bcx, datum.ty);
1912 if cast_is_noop(bcx.tcx(), expr, datum_ty, t_out) {
1914 return DatumBlock::new(bcx, datum);
1917 if type_is_fat_ptr(bcx.tcx(), t_in) {
1918 assert!(datum.kind.is_by_ref());
1919 if type_is_fat_ptr(bcx.tcx(), t_out) {
1920 return DatumBlock::new(bcx, Datum::new(
1921 PointerCast(bcx, datum.val, ll_t_out.ptr_to()),
1924 )).to_expr_datumblock();
1926 // Return the address
1927 return immediate_rvalue_bcx(bcx,
1929 Load(bcx, get_dataptr(bcx, datum.val)),
1931 t_out).to_expr_datumblock();
1935 let r_t_in = CastTy::from_ty(t_in).expect("bad input type for cast");
1936 let r_t_out = CastTy::from_ty(t_out).expect("bad output type for cast");
1938 let (llexpr, signed) = if let Int(CEnum) = r_t_in {
1939 let repr = adt::represent_type(ccx, t_in);
1940 let datum = unpack_datum!(
1941 bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
1942 let llexpr_ptr = datum.to_llref();
1943 let discr = adt::trans_get_discr(bcx, &repr, llexpr_ptr,
1944 Some(Type::i64(ccx)), true);
1945 ll_t_in = val_ty(discr);
1946 (discr, adt::is_discr_signed(&repr))
1948 (datum.to_llscalarish(bcx), t_in.is_signed())
1951 let newval = match (r_t_in, r_t_out) {
1952 (Ptr(_), Ptr(_)) | (FnPtr, Ptr(_)) | (RPtr(_), Ptr(_)) => {
1953 PointerCast(bcx, llexpr, ll_t_out)
1955 (Ptr(_), Int(_)) | (FnPtr, Int(_)) => PtrToInt(bcx, llexpr, ll_t_out),
1956 (Int(_), Ptr(_)) => IntToPtr(bcx, llexpr, ll_t_out),
1958 (Int(_), Int(_)) => int_cast(bcx, ll_t_out, ll_t_in, llexpr, signed),
1959 (Float, Float) => float_cast(bcx, ll_t_out, ll_t_in, llexpr),
1960 (Int(_), Float) if signed => SIToFP(bcx, llexpr, ll_t_out),
1961 (Int(_), Float) => UIToFP(bcx, llexpr, ll_t_out),
1962 (Float, Int(I)) => FPToSI(bcx, llexpr, ll_t_out),
1963 (Float, Int(_)) => FPToUI(bcx, llexpr, ll_t_out),
1965 _ => ccx.sess().span_bug(expr.span,
1966 &format!("translating unsupported cast: \
1972 return immediate_rvalue_bcx(bcx, newval, t_out).to_expr_datumblock();
1975 fn trans_assign_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1980 -> Block<'blk, 'tcx> {
1981 let _icx = push_ctxt("trans_assign_op");
1984 debug!("trans_assign_op(expr={:?})", expr);
1986 // User-defined operator methods cannot be used with `+=` etc right now
1987 assert!(!bcx.tcx().is_method_call(expr.id));
1989 // Evaluate LHS (destination), which should be an lvalue
1990 let dst = unpack_datum!(bcx, trans_to_lvalue(bcx, dst, "assign_op"));
1991 assert!(!bcx.fcx.type_needs_drop(dst.ty));
1992 let lhs = load_ty(bcx, dst.val, dst.ty);
1993 let lhs = immediate_rvalue(lhs, dst.ty);
1995 // Evaluate RHS - FIXME(#28160) this sucks
1996 let rhs = unpack_datum!(bcx, trans(bcx, &src));
1997 let rhs = unpack_datum!(bcx, rhs.to_rvalue_datum(bcx, "assign_op_rhs"));
1999 // Perform computation and store the result
2000 let result_datum = unpack_datum!(
2001 bcx, trans_scalar_binop(bcx, expr, dst.ty, op, lhs, rhs));
2002 return result_datum.store_to(bcx, dst.val);
2005 fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2006 datum: Datum<'tcx, Expr>,
2008 -> DatumBlock<'blk, 'tcx, Expr> {
2011 // Ensure cleanup of `datum` if not already scheduled and obtain
2012 // a "by ref" pointer.
2013 let lv_datum = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "autoref", expr.id));
2015 // Compute final type. Note that we are loose with the region and
2016 // mutability, since those things don't matter in trans.
2017 let referent_ty = lv_datum.ty;
2018 let ptr_ty = bcx.tcx().mk_imm_ref(bcx.tcx().mk_region(ty::ReStatic), referent_ty);
2020 // Construct the resulting datum. The right datum to return here would be an Lvalue datum,
2021 // because there is cleanup scheduled and the datum doesn't own the data, but for thin pointers
2022 // we microoptimize it to be an Rvalue datum to avoid the extra alloca and level of
2023 // indirection and for thin pointers, this has no ill effects.
2024 let kind = if type_is_sized(bcx.tcx(), referent_ty) {
2025 RvalueExpr(Rvalue::new(ByValue))
2027 LvalueExpr(lv_datum.kind)
2031 let llref = lv_datum.to_llref();
2032 DatumBlock::new(bcx, Datum::new(llref, ptr_ty, kind))
2035 fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2037 datum: Datum<'tcx, Expr>,
2039 -> DatumBlock<'blk, 'tcx, Expr> {
2041 let mut datum = datum;
2043 let method_call = MethodCall::autoderef(expr.id, i as u32);
2044 datum = unpack_datum!(bcx, deref_once(bcx, expr, datum, method_call));
2046 DatumBlock { bcx: bcx, datum: datum }
2049 fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2051 datum: Datum<'tcx, Expr>,
2052 method_call: MethodCall)
2053 -> DatumBlock<'blk, 'tcx, Expr> {
2054 let ccx = bcx.ccx();
2056 debug!("deref_once(expr={:?}, datum={:?}, method_call={:?})",
2057 expr, datum, method_call);
2061 // Check for overloaded deref.
2062 let method = ccx.tcx().tables.borrow().method_map.get(&method_call).cloned();
2063 let datum = match method {
2065 let method_ty = monomorphize_type(bcx, method.ty);
2067 // Overloaded. Invoke the deref() method, which basically
2068 // converts from the `Smaht<T>` pointer that we have into
2069 // a `&T` pointer. We can then proceed down the normal
2070 // path (below) to dereference that `&T`.
2071 let datum = if method_call.autoderef == 0 {
2074 // Always perform an AutoPtr when applying an overloaded auto-deref
2075 unpack_datum!(bcx, auto_ref(bcx, datum, expr))
2078 let ref_ty = // invoked methods have their LB regions instantiated
2079 ccx.tcx().no_late_bound_regions(&method_ty.fn_ret()).unwrap().unwrap();
2080 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_deref");
2082 bcx = Callee::method(bcx, method)
2083 .call(bcx, expr.debug_loc(),
2084 ArgOverloadedOp(datum, None),
2085 Some(SaveIn(scratch.val))).bcx;
2086 scratch.to_expr_datum()
2089 // Not overloaded. We already have a pointer we know how to deref.
2094 let r = match datum.ty.sty {
2095 ty::TyBox(content_ty) => {
2096 // Make sure we have an lvalue datum here to get the
2097 // proper cleanups scheduled
2098 let datum = unpack_datum!(
2099 bcx, datum.to_lvalue_datum(bcx, "deref", expr.id));
2101 if type_is_sized(bcx.tcx(), content_ty) {
2102 let ptr = load_ty(bcx, datum.val, datum.ty);
2103 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr(datum.kind)))
2105 // A fat pointer and a DST lvalue have the same representation
2106 // just different types. Since there is no temporary for `*e`
2107 // here (because it is unsized), we cannot emulate the sized
2108 // object code path for running drop glue and free. Instead,
2109 // we schedule cleanup for `e`, turning it into an lvalue.
2111 let lval = Lvalue::new("expr::deref_once ty_uniq");
2112 let datum = Datum::new(datum.val, content_ty, LvalueExpr(lval));
2113 DatumBlock::new(bcx, datum)
2117 ty::TyRawPtr(ty::TypeAndMut { ty: content_ty, .. }) |
2118 ty::TyRef(_, ty::TypeAndMut { ty: content_ty, .. }) => {
2119 let lval = Lvalue::new("expr::deref_once ptr");
2120 if type_is_sized(bcx.tcx(), content_ty) {
2121 let ptr = datum.to_llscalarish(bcx);
2123 // Always generate an lvalue datum, even if datum.mode is
2124 // an rvalue. This is because datum.mode is only an
2125 // rvalue for non-owning pointers like &T or *T, in which
2126 // case cleanup *is* scheduled elsewhere, by the true
2127 // owner (or, in the case of *T, by the user).
2128 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr(lval)))
2130 // A fat pointer and a DST lvalue have the same representation
2131 // just different types.
2132 DatumBlock::new(bcx, Datum::new(datum.val, content_ty, LvalueExpr(lval)))
2137 bcx.tcx().sess.span_bug(
2139 &format!("deref invoked on expr of invalid type {:?}",
2144 debug!("deref_once(expr={}, method_call={:?}, result={:?})",
2145 expr.id, method_call, r.datum);
2160 fn codegen_strategy(&self) -> OverflowCodegen {
2161 use self::OverflowCodegen::{ViaIntrinsic, ViaInputCheck};
2163 OverflowOp::Add => ViaIntrinsic(OverflowOpViaIntrinsic::Add),
2164 OverflowOp::Sub => ViaIntrinsic(OverflowOpViaIntrinsic::Sub),
2165 OverflowOp::Mul => ViaIntrinsic(OverflowOpViaIntrinsic::Mul),
2167 OverflowOp::Shl => ViaInputCheck(OverflowOpViaInputCheck::Shl),
2168 OverflowOp::Shr => ViaInputCheck(OverflowOpViaInputCheck::Shr),
2173 enum OverflowCodegen {
2174 ViaIntrinsic(OverflowOpViaIntrinsic),
2175 ViaInputCheck(OverflowOpViaInputCheck),
2178 enum OverflowOpViaInputCheck { Shl, Shr, }
2181 enum OverflowOpViaIntrinsic { Add, Sub, Mul, }
2183 impl OverflowOpViaIntrinsic {
2184 fn to_intrinsic<'blk, 'tcx>(&self, bcx: Block<'blk, 'tcx>, lhs_ty: Ty) -> ValueRef {
2185 let name = self.to_intrinsic_name(bcx.tcx(), lhs_ty);
2186 bcx.ccx().get_intrinsic(&name)
2188 fn to_intrinsic_name(&self, tcx: &TyCtxt, ty: Ty) -> &'static str {
2189 use syntax::ast::IntTy::*;
2190 use syntax::ast::UintTy::*;
2191 use middle::ty::{TyInt, TyUint};
2193 let new_sty = match ty.sty {
2194 TyInt(Is) => match &tcx.sess.target.target.target_pointer_width[..] {
2197 _ => panic!("unsupported target word size")
2199 TyUint(Us) => match &tcx.sess.target.target.target_pointer_width[..] {
2200 "32" => TyUint(U32),
2201 "64" => TyUint(U64),
2202 _ => panic!("unsupported target word size")
2204 ref t @ TyUint(_) | ref t @ TyInt(_) => t.clone(),
2205 _ => panic!("tried to get overflow intrinsic for {:?} applied to non-int type",
2210 OverflowOpViaIntrinsic::Add => match new_sty {
2211 TyInt(I8) => "llvm.sadd.with.overflow.i8",
2212 TyInt(I16) => "llvm.sadd.with.overflow.i16",
2213 TyInt(I32) => "llvm.sadd.with.overflow.i32",
2214 TyInt(I64) => "llvm.sadd.with.overflow.i64",
2216 TyUint(U8) => "llvm.uadd.with.overflow.i8",
2217 TyUint(U16) => "llvm.uadd.with.overflow.i16",
2218 TyUint(U32) => "llvm.uadd.with.overflow.i32",
2219 TyUint(U64) => "llvm.uadd.with.overflow.i64",
2221 _ => unreachable!(),
2223 OverflowOpViaIntrinsic::Sub => match new_sty {
2224 TyInt(I8) => "llvm.ssub.with.overflow.i8",
2225 TyInt(I16) => "llvm.ssub.with.overflow.i16",
2226 TyInt(I32) => "llvm.ssub.with.overflow.i32",
2227 TyInt(I64) => "llvm.ssub.with.overflow.i64",
2229 TyUint(U8) => "llvm.usub.with.overflow.i8",
2230 TyUint(U16) => "llvm.usub.with.overflow.i16",
2231 TyUint(U32) => "llvm.usub.with.overflow.i32",
2232 TyUint(U64) => "llvm.usub.with.overflow.i64",
2234 _ => unreachable!(),
2236 OverflowOpViaIntrinsic::Mul => match new_sty {
2237 TyInt(I8) => "llvm.smul.with.overflow.i8",
2238 TyInt(I16) => "llvm.smul.with.overflow.i16",
2239 TyInt(I32) => "llvm.smul.with.overflow.i32",
2240 TyInt(I64) => "llvm.smul.with.overflow.i64",
2242 TyUint(U8) => "llvm.umul.with.overflow.i8",
2243 TyUint(U16) => "llvm.umul.with.overflow.i16",
2244 TyUint(U32) => "llvm.umul.with.overflow.i32",
2245 TyUint(U64) => "llvm.umul.with.overflow.i64",
2247 _ => unreachable!(),
2252 fn build_intrinsic_call<'blk, 'tcx>(&self, bcx: Block<'blk, 'tcx>,
2253 info: NodeIdAndSpan,
2254 lhs_t: Ty<'tcx>, lhs: ValueRef,
2256 binop_debug_loc: DebugLoc)
2257 -> (Block<'blk, 'tcx>, ValueRef) {
2258 let llfn = self.to_intrinsic(bcx, lhs_t);
2260 let val = Call(bcx, llfn, &[lhs, rhs], None, binop_debug_loc);
2261 let result = ExtractValue(bcx, val, 0); // iN operation result
2262 let overflow = ExtractValue(bcx, val, 1); // i1 "did it overflow?"
2264 let cond = ICmp(bcx, llvm::IntEQ, overflow, C_integral(Type::i1(bcx.ccx()), 1, false),
2267 let expect = bcx.ccx().get_intrinsic(&"llvm.expect.i1");
2268 Call(bcx, expect, &[cond, C_integral(Type::i1(bcx.ccx()), 0, false)],
2269 None, binop_debug_loc);
2272 base::with_cond(bcx, cond, |bcx|
2273 controlflow::trans_fail(bcx, info,
2274 InternedString::new("arithmetic operation overflowed")));
2280 impl OverflowOpViaInputCheck {
2281 fn build_with_input_check<'blk, 'tcx>(&self,
2282 bcx: Block<'blk, 'tcx>,
2283 info: NodeIdAndSpan,
2287 binop_debug_loc: DebugLoc)
2288 -> (Block<'blk, 'tcx>, ValueRef)
2290 let lhs_llty = val_ty(lhs);
2291 let rhs_llty = val_ty(rhs);
2293 // Panic if any bits are set outside of bits that we always
2296 // Note that the mask's value is derived from the LHS type
2297 // (since that is where the 32/64 distinction is relevant) but
2298 // the mask's type must match the RHS type (since they will
2299 // both be fed into an and-binop)
2300 let invert_mask = shift_mask_val(bcx, lhs_llty, rhs_llty, true);
2302 let outer_bits = And(bcx, rhs, invert_mask, binop_debug_loc);
2303 let cond = build_nonzero_check(bcx, outer_bits, binop_debug_loc);
2304 let result = match *self {
2305 OverflowOpViaInputCheck::Shl =>
2306 build_unchecked_lshift(bcx, lhs, rhs, binop_debug_loc),
2307 OverflowOpViaInputCheck::Shr =>
2308 build_unchecked_rshift(bcx, lhs_t, lhs, rhs, binop_debug_loc),
2311 base::with_cond(bcx, cond, |bcx|
2312 controlflow::trans_fail(bcx, info,
2313 InternedString::new("shift operation overflowed")));
2319 // Check if an integer or vector contains a nonzero element.
2320 fn build_nonzero_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2322 binop_debug_loc: DebugLoc) -> ValueRef {
2323 let llty = val_ty(value);
2324 let kind = llty.kind();
2326 TypeKind::Integer => ICmp(bcx, llvm::IntNE, value, C_null(llty), binop_debug_loc),
2327 TypeKind::Vector => {
2328 // Check if any elements of the vector are nonzero by treating
2329 // it as a wide integer and checking if the integer is nonzero.
2330 let width = llty.vector_length() as u64 * llty.element_type().int_width();
2331 let int_value = BitCast(bcx, value, Type::ix(bcx.ccx(), width));
2332 build_nonzero_check(bcx, int_value, binop_debug_loc)
2334 _ => panic!("build_nonzero_check: expected Integer or Vector, found {:?}", kind),
2338 fn with_overflow_check<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, oop: OverflowOp, info: NodeIdAndSpan,
2339 lhs_t: Ty<'tcx>, lhs: ValueRef,
2341 binop_debug_loc: DebugLoc)
2342 -> (Block<'blk, 'tcx>, ValueRef) {
2343 if bcx.unreachable.get() { return (bcx, _Undef(lhs)); }
2344 if bcx.ccx().check_overflow() {
2346 match oop.codegen_strategy() {
2347 OverflowCodegen::ViaIntrinsic(oop) =>
2348 oop.build_intrinsic_call(bcx, info, lhs_t, lhs, rhs, binop_debug_loc),
2349 OverflowCodegen::ViaInputCheck(oop) =>
2350 oop.build_with_input_check(bcx, info, lhs_t, lhs, rhs, binop_debug_loc),
2353 let res = match oop {
2354 OverflowOp::Add => Add(bcx, lhs, rhs, binop_debug_loc),
2355 OverflowOp::Sub => Sub(bcx, lhs, rhs, binop_debug_loc),
2356 OverflowOp::Mul => Mul(bcx, lhs, rhs, binop_debug_loc),
2359 build_unchecked_lshift(bcx, lhs, rhs, binop_debug_loc),
2361 build_unchecked_rshift(bcx, lhs_t, lhs, rhs, binop_debug_loc),
2367 /// We categorize expressions into three kinds. The distinction between
2368 /// lvalue/rvalue is fundamental to the language. The distinction between the
2369 /// two kinds of rvalues is an artifact of trans which reflects how we will
2370 /// generate code for that kind of expression. See trans/expr.rs for more
2372 #[derive(Copy, Clone)]
2380 fn expr_kind(tcx: &TyCtxt, expr: &hir::Expr) -> ExprKind {
2381 if tcx.is_method_call(expr.id) {
2382 // Overloaded operations are generally calls, and hence they are
2383 // generated via DPS, but there are a few exceptions:
2384 return match expr.node {
2385 // `a += b` has a unit result.
2386 hir::ExprAssignOp(..) => ExprKind::RvalueStmt,
2388 // the deref method invoked for `*a` always yields an `&T`
2389 hir::ExprUnary(hir::UnDeref, _) => ExprKind::Lvalue,
2391 // the index method invoked for `a[i]` always yields an `&T`
2392 hir::ExprIndex(..) => ExprKind::Lvalue,
2394 // in the general case, result could be any type, use DPS
2395 _ => ExprKind::RvalueDps
2400 hir::ExprPath(..) => {
2401 match tcx.resolve_expr(expr) {
2402 // Put functions and ctors with the ADTs, as they
2403 // are zero-sized, so DPS is the cheapest option.
2404 Def::Struct(..) | Def::Variant(..) |
2405 Def::Fn(..) | Def::Method(..) => {
2409 // Note: there is actually a good case to be made that
2410 // DefArg's, particularly those of immediate type, ought to
2411 // considered rvalues.
2414 Def::Local(..) => ExprKind::Lvalue,
2417 Def::AssociatedConst(..) => ExprKind::RvalueDatum,
2422 &format!("uncategorized def for expr {}: {:?}",
2429 hir::ExprType(ref expr, _) => {
2430 expr_kind(tcx, expr)
2433 hir::ExprUnary(hir::UnDeref, _) |
2434 hir::ExprField(..) |
2435 hir::ExprTupField(..) |
2436 hir::ExprIndex(..) => {
2441 hir::ExprMethodCall(..) |
2442 hir::ExprStruct(..) |
2445 hir::ExprMatch(..) |
2446 hir::ExprClosure(..) |
2447 hir::ExprBlock(..) |
2448 hir::ExprRepeat(..) |
2449 hir::ExprVec(..) => {
2453 hir::ExprLit(ref lit) if lit.node.is_str() => {
2457 hir::ExprBreak(..) |
2458 hir::ExprAgain(..) |
2460 hir::ExprWhile(..) |
2462 hir::ExprAssign(..) |
2463 hir::ExprInlineAsm(..) |
2464 hir::ExprAssignOp(..) => {
2465 ExprKind::RvalueStmt
2468 hir::ExprLit(_) | // Note: LitStr is carved out above
2469 hir::ExprUnary(..) |
2471 hir::ExprAddrOf(..) |
2472 hir::ExprBinary(..) |
2473 hir::ExprCast(..) => {
2474 ExprKind::RvalueDatum