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.
12 * # Translation of Expressions
14 * Public entry points:
16 * - `trans_into(bcx, expr, dest) -> bcx`: evaluates an expression,
17 * storing the result into `dest`. This is the preferred form, if you
20 * - `trans(bcx, expr) -> DatumBlock`: evaluates an expression, yielding
21 * `Datum` with the result. You can then store the datum, inspect
22 * the value, etc. This may introduce temporaries if the datum is a
25 * - `trans_to_lvalue(bcx, expr, "...") -> DatumBlock`: evaluates an
26 * expression and ensures that the result has a cleanup associated with it,
27 * creating a temporary stack slot if necessary.
29 * - `trans_local_var -> Datum`: looks up a local variable or upvar.
31 * See doc.rs for more comments.
34 #![allow(non_camel_case_types)]
40 use middle::mem_categorization::Typer;
42 use middle::subst::Subst;
43 use middle::trans::_match;
44 use middle::trans::adt;
45 use middle::trans::asm;
46 use middle::trans::base::*;
47 use middle::trans::base;
48 use middle::trans::build::*;
49 use middle::trans::callee;
50 use middle::trans::cleanup;
51 use middle::trans::cleanup::CleanupMethods;
52 use middle::trans::closure;
53 use middle::trans::common::*;
54 use middle::trans::consts;
55 use middle::trans::controlflow;
56 use middle::trans::datum::*;
57 use middle::trans::debuginfo;
58 use middle::trans::glue;
59 use middle::trans::machine;
60 use middle::trans::meth;
61 use middle::trans::inline;
62 use middle::trans::tvec;
63 use middle::trans::type_of;
64 use middle::ty::{struct_fields, tup_fields};
65 use middle::ty::{AdjustDerefRef, AdjustAddEnv, AutoUnsafe};
66 use middle::ty::{AutoPtr};
69 use middle::typeck::MethodCall;
70 use util::common::indenter;
71 use util::ppaux::Repr;
72 use middle::trans::machine::{llsize_of, llsize_of_alloc};
73 use middle::trans::type_::Type;
77 use syntax::print::pprust::{expr_to_string};
83 // These are passed around by the code generating functions to track the
84 // destination of a computation's value.
86 #[deriving(PartialEq)]
93 pub fn to_string(&self, ccx: &CrateContext) -> String {
95 SaveIn(v) => format!("SaveIn({})", ccx.tn().val_to_string(v)),
96 Ignore => "Ignore".to_string()
101 pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
104 -> Block<'blk, 'tcx> {
106 * This function is equivalent to `trans(bcx, expr).store_to_dest(dest)`
107 * but it may generate better optimized LLVM code.
112 if bcx.tcx().adjustments.borrow().contains_key(&expr.id) {
113 // use trans, which may be less efficient but
114 // which will perform the adjustments:
115 let datum = unpack_datum!(bcx, trans(bcx, expr));
116 return datum.store_to_dest(bcx, dest, expr.id)
119 debug!("trans_into() expr={}", expr.repr(bcx.tcx()));
121 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(expr.id,
124 bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
126 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
127 let kind = ty::expr_kind(bcx.tcx(), expr);
129 ty::LvalueExpr | ty::RvalueDatumExpr => {
130 trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
132 ty::RvalueDpsExpr => {
133 trans_rvalue_dps_unadjusted(bcx, expr, dest)
135 ty::RvalueStmtExpr => {
136 trans_rvalue_stmt_unadjusted(bcx, expr)
140 bcx.fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id)
143 pub fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
145 -> DatumBlock<'blk, 'tcx, Expr> {
147 * Translates an expression, returning a datum (and new block)
148 * encapsulating the result. When possible, it is preferred to
149 * use `trans_into`, as that may avoid creating a temporary on
153 debug!("trans(expr={})", bcx.expr_to_string(expr));
158 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(expr.id,
161 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
162 let datum = unpack_datum!(bcx, trans_unadjusted(bcx, expr));
163 let datum = unpack_datum!(bcx, apply_adjustments(bcx, expr, datum));
164 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id);
165 return DatumBlock::new(bcx, datum);
168 pub fn get_len(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
169 GEPi(bcx, fat_ptr, [0u, abi::slice_elt_len])
172 pub fn get_dataptr(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
173 GEPi(bcx, fat_ptr, [0u, abi::slice_elt_base])
176 fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
179 -> DatumBlock<'blk, 'tcx, Expr> {
181 * Helper for trans that apply adjustments from `expr` to `datum`,
182 * which should be the unadjusted translation of `expr`.
186 let mut datum = datum;
187 let adjustment = match bcx.tcx().adjustments.borrow().find_copy(&expr.id) {
189 return DatumBlock::new(bcx, datum);
193 debug!("unadjusted datum for expr {}: {}",
194 expr.id, datum.to_string(bcx.ccx()));
196 AdjustAddEnv(..) => {
197 datum = unpack_datum!(bcx, add_env(bcx, expr, datum));
199 AdjustDerefRef(ref adj) => {
200 let (autoderefs, use_autoref) = match adj.autoref {
201 // Extracting a value from a box counts as a deref, but if we are
202 // just converting Box<[T, ..n]> to Box<[T]> we aren't really doing
203 // a deref (and wouldn't if we could treat Box like a normal struct).
204 Some(ty::AutoUnsizeUniq(..)) => (adj.autoderefs - 1, true),
205 // We are a bit paranoid about adjustments and thus might have a re-
206 // borrow here which merely derefs and then refs again (it might have
207 // a different region or mutability, but we don't care here. It might
208 // also be just in case we need to unsize. But if there are no nested
209 // adjustments then it should be a no-op).
210 Some(ty::AutoPtr(_, _, None)) if adj.autoderefs == 1 => {
211 match ty::get(datum.ty).sty {
212 // Don't skip a conversion from Box<T> to &T, etc.
214 let method_call = MethodCall::autoderef(expr.id, adj.autoderefs-1);
215 let method = bcx.tcx().method_map.borrow().find(&method_call).is_some();
217 // Don't skip an overloaded deref.
218 (adj.autoderefs, true)
220 (adj.autoderefs - 1, false)
223 _ => (adj.autoderefs, true),
226 _ => (adj.autoderefs, true)
231 let lval = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "auto_deref", expr.id));
232 datum = unpack_datum!(
233 bcx, deref_multiple(bcx, expr, lval.to_expr_datum(), autoderefs));
236 // (You might think there is a more elegant way to do this than a
237 // use_autoref bool, but then you remember that the borrow checker exists).
238 match (use_autoref, &adj.autoref) {
239 (true, &Some(ref a)) => {
240 datum = unpack_datum!(bcx, apply_autoref(a,
249 debug!("after adjustments, datum={}", datum.to_string(bcx.ccx()));
250 return DatumBlock::new(bcx, datum);
252 fn apply_autoref<'blk, 'tcx>(autoref: &ty::AutoRef,
253 bcx: Block<'blk, 'tcx>,
256 -> DatumBlock<'blk, 'tcx, Expr> {
258 let mut datum = datum;
260 let datum = match autoref {
261 &AutoPtr(_, _, ref a) | &AutoUnsafe(_, ref a) => {
264 &Some(box ref a) => datum = unpack_datum!(bcx,
265 apply_autoref(a, bcx, expr, datum)),
268 unpack_datum!(bcx, ref_ptr(bcx, expr, datum))
270 &ty::AutoUnsize(ref k) => {
271 debug!(" AutoUnsize");
272 unpack_datum!(bcx, unsize_expr(bcx, expr, datum, k))
275 &ty::AutoUnsizeUniq(ty::UnsizeLength(len)) => {
276 debug!(" AutoUnsizeUniq(UnsizeLength)");
277 unpack_datum!(bcx, unsize_unique_vec(bcx, expr, datum, len))
279 &ty::AutoUnsizeUniq(ref k) => {
280 debug!(" AutoUnsizeUniq");
281 unpack_datum!(bcx, unsize_unique_expr(bcx, expr, datum, k))
285 DatumBlock::new(bcx, datum)
288 fn ref_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
291 -> DatumBlock<'blk, 'tcx, Expr> {
292 if !ty::type_is_sized(bcx.tcx(), datum.ty) {
293 debug!("Taking address of unsized type {}",
294 bcx.ty_to_string(datum.ty));
295 ref_fat_ptr(bcx, expr, datum)
297 debug!("Taking address of sized type {}",
298 bcx.ty_to_string(datum.ty));
299 auto_ref(bcx, datum, expr)
303 // Retrieve the information we are losing (making dynamic) in an unsizing
305 // When making a dtor, we need to do different things depending on the
306 // ownership of the object.. mk_ty is a function for turning unsized_type
307 // into a type to be destructed. If we want to end up with a Box pointer,
308 // then mk_ty should make a Box pointer (T -> Box<T>), if we want a
309 // borrowed reference then it should be T -> &T.
310 fn unsized_info<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
311 kind: &ty::UnsizeKind,
314 mk_ty: |ty::t| -> ty::t) -> ValueRef {
316 &ty::UnsizeLength(len) => C_uint(bcx.ccx(), len),
317 &ty::UnsizeStruct(box ref k, tp_index) => match ty::get(unsized_ty).sty {
318 ty::ty_struct(_, ref substs) => {
319 let ty_substs = substs.types.get_slice(subst::TypeSpace);
320 // The dtor for a field treats it like a value, so mk_ty
321 // should just be the identity function.
322 unsized_info(bcx, k, id, ty_substs[tp_index], |t| t)
324 _ => bcx.sess().bug(format!("UnsizeStruct with bad sty: {}",
325 bcx.ty_to_string(unsized_ty)).as_slice())
327 &ty::UnsizeVtable(ty::TyTrait { def_id, ref substs, .. }, _) => {
328 let substs = substs.with_self_ty(unsized_ty);
330 Rc::new(ty::TraitRef { def_id: def_id,
333 trait_ref.subst(bcx.tcx(), &bcx.fcx.param_substs.substs);
334 let box_ty = mk_ty(unsized_ty);
336 meth::get_vtable(bcx, box_ty, trait_ref),
337 Type::vtable_ptr(bcx.ccx()))
342 fn unsize_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
346 -> DatumBlock<'blk, 'tcx, Expr> {
348 let datum_ty = datum.ty;
349 let unsized_ty = ty::unsize_ty(tcx, datum_ty, k, expr.span);
350 let dest_ty = ty::mk_open(tcx, unsized_ty);
351 // Closures for extracting and manipulating the data and payload parts of
354 &ty::UnsizeStruct(..) =>
355 |bcx, val| PointerCast(bcx,
357 type_of::type_of(bcx.ccx(), unsized_ty).ptr_to()),
358 &ty::UnsizeLength(..) =>
359 |bcx, val| GEPi(bcx, val, [0u, 0u]),
360 &ty::UnsizeVtable(..) =>
361 |_bcx, val| PointerCast(bcx, val, Type::i8p(bcx.ccx()))
363 let info = |bcx, _val| unsized_info(bcx,
366 ty::deref_or_dont(datum_ty),
371 mutbl: ast::MutImmutable
373 into_fat_ptr(bcx, expr, datum, dest_ty, base, info)
376 fn ref_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
379 -> DatumBlock<'blk, 'tcx, Expr> {
381 let dest_ty = ty::close_type(tcx, datum.ty);
382 let base = |bcx, val| Load(bcx, get_dataptr(bcx, val));
383 let len = |bcx, val| Load(bcx, get_len(bcx, val));
384 into_fat_ptr(bcx, expr, datum, dest_ty, base, len)
387 fn into_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
391 base: |Block<'blk, 'tcx>, ValueRef| -> ValueRef,
392 info: |Block<'blk, 'tcx>, ValueRef| -> ValueRef)
393 -> DatumBlock<'blk, 'tcx, Expr> {
397 let lval = unpack_datum!(bcx,
398 datum.to_lvalue_datum(bcx, "into_fat_ptr", expr.id));
399 let base = base(bcx, lval.val);
400 let info = info(bcx, lval.val);
402 let scratch = rvalue_scratch_datum(bcx, dest_ty, "__fat_ptr");
403 Store(bcx, base, get_dataptr(bcx, scratch.val));
404 Store(bcx, info, get_len(bcx, scratch.val));
406 DatumBlock::new(bcx, scratch.to_expr_datum())
409 fn unsize_unique_vec<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
413 -> DatumBlock<'blk, 'tcx, Expr> {
417 let datum_ty = datum.ty;
419 let lval = unpack_datum!(bcx,
420 datum.to_lvalue_datum(bcx, "unsize_unique_vec", expr.id));
422 let ll_len = C_uint(bcx.ccx(), len);
423 let unit_ty = ty::sequence_element_type(tcx, ty::type_content(datum_ty));
424 let vec_ty = ty::mk_uniq(tcx, ty::mk_vec(tcx, unit_ty, None));
425 let scratch = rvalue_scratch_datum(bcx, vec_ty, "__unsize_unique");
427 let base = get_dataptr(bcx, scratch.val);
428 let base = PointerCast(bcx,
430 type_of::type_of(bcx.ccx(), datum_ty).ptr_to());
431 bcx = lval.store_to(bcx, base);
433 Store(bcx, ll_len, get_len(bcx, scratch.val));
434 DatumBlock::new(bcx, scratch.to_expr_datum())
437 fn unsize_unique_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
441 -> DatumBlock<'blk, 'tcx, Expr> {
445 let datum_ty = datum.ty;
446 let unboxed_ty = match ty::get(datum_ty).sty {
448 _ => bcx.sess().bug(format!("Expected ty_uniq, found {}",
449 bcx.ty_to_string(datum_ty)).as_slice())
451 let result_ty = ty::mk_uniq(tcx, ty::unsize_ty(tcx, unboxed_ty, k, expr.span));
453 let lval = unpack_datum!(bcx,
454 datum.to_lvalue_datum(bcx, "unsize_unique_expr", expr.id));
456 let scratch = rvalue_scratch_datum(bcx, result_ty, "__uniq_fat_ptr");
457 let llbox_ty = type_of::type_of(bcx.ccx(), datum_ty);
458 let base = PointerCast(bcx, get_dataptr(bcx, scratch.val), llbox_ty.ptr_to());
459 bcx = lval.store_to(bcx, base);
461 let info = unsized_info(bcx, k, expr.id, unboxed_ty, |t| ty::mk_uniq(tcx, t));
462 Store(bcx, info, get_len(bcx, scratch.val));
464 let scratch = unpack_datum!(bcx,
465 scratch.to_expr_datum().to_lvalue_datum(bcx,
466 "fresh_uniq_fat_ptr",
469 DatumBlock::new(bcx, scratch.to_expr_datum())
472 fn add_env<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
475 -> DatumBlock<'blk, 'tcx, Expr> {
476 // This is not the most efficient thing possible; since closures
477 // are two words it'd be better if this were compiled in
478 // 'dest' mode, but I can't find a nice way to structure the
479 // code and keep it DRY that accommodates that use case at the
482 let closure_ty = expr_ty_adjusted(bcx, expr);
483 let fn_ptr = datum.to_llscalarish(bcx);
484 let def = ty::resolve_expr(bcx.tcx(), expr);
485 closure::make_closure_from_bare_fn(bcx, closure_ty, def, fn_ptr)
489 pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
492 -> DatumBlock<'blk, 'tcx, Lvalue> {
494 * Translates an expression in "lvalue" mode -- meaning that it
495 * returns a reference to the memory that the expr represents.
497 * If this expression is an rvalue, this implies introducing a
498 * temporary. In other words, something like `x().f` is
499 * translated into roughly the equivalent of
501 * { tmp = x(); tmp.f }
505 let datum = unpack_datum!(bcx, trans(bcx, expr));
506 return datum.to_lvalue_datum(bcx, name, expr.id);
509 fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
511 -> DatumBlock<'blk, 'tcx, Expr> {
513 * A version of `trans` that ignores adjustments. You almost
514 * certainly do not want to call this directly.
519 debug!("trans_unadjusted(expr={})", bcx.expr_to_string(expr));
520 let _indenter = indenter();
522 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
524 return match ty::expr_kind(bcx.tcx(), expr) {
525 ty::LvalueExpr | ty::RvalueDatumExpr => {
526 let datum = unpack_datum!(bcx, {
527 trans_datum_unadjusted(bcx, expr)
530 DatumBlock {bcx: bcx, datum: datum}
533 ty::RvalueStmtExpr => {
534 bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
535 nil(bcx, expr_ty(bcx, expr))
538 ty::RvalueDpsExpr => {
539 let ty = expr_ty(bcx, expr);
540 if type_is_zero_size(bcx.ccx(), ty) {
541 bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
544 let scratch = rvalue_scratch_datum(bcx, ty, "");
545 bcx = trans_rvalue_dps_unadjusted(
546 bcx, expr, SaveIn(scratch.val));
548 // Note: this is not obviously a good idea. It causes
549 // immediate values to be loaded immediately after a
550 // return from a call or other similar expression,
551 // which in turn leads to alloca's having shorter
552 // lifetimes and hence larger stack frames. However,
553 // in turn it can lead to more register pressure.
554 // Still, in practice it seems to increase
555 // performance, since we have fewer problems with
557 let scratch = unpack_datum!(
558 bcx, scratch.to_appropriate_datum(bcx));
560 DatumBlock::new(bcx, scratch.to_expr_datum())
565 fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: ty::t)
566 -> DatumBlock<'blk, 'tcx, Expr> {
567 let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
568 let datum = immediate_rvalue(llval, ty);
569 DatumBlock::new(bcx, datum.to_expr_datum())
573 fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
575 -> DatumBlock<'blk, 'tcx, Expr> {
578 let _icx = push_ctxt("trans_datum_unadjusted");
581 ast::ExprParen(ref e) => {
584 ast::ExprPath(_) => {
585 trans_def(bcx, expr, bcx.def(expr.id))
587 ast::ExprField(ref base, ident, _) => {
588 trans_rec_field(bcx, &**base, ident.node)
590 ast::ExprTupField(ref base, idx, _) => {
591 trans_rec_tup_field(bcx, &**base, idx.node)
593 ast::ExprIndex(ref base, ref idx) => {
594 trans_index(bcx, expr, &**base, &**idx, MethodCall::expr(expr.id))
596 ast::ExprSlice(ref base, ref start, ref end, _) => {
597 let _icx = push_ctxt("trans_slice");
600 let method_call = MethodCall::expr(expr.id);
601 let method_ty = ccx.tcx()
605 .map(|method| method.ty);
606 let base_datum = unpack_datum!(bcx, trans(bcx, &**base));
608 let mut args = vec![];
609 start.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
610 end.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
612 let result_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty.unwrap())).unwrap();
613 let scratch = rvalue_scratch_datum(bcx, result_ty, "trans_slice");
616 trans_overloaded_op(bcx,
621 Some(SaveIn(scratch.val))));
622 DatumBlock::new(bcx, scratch.to_expr_datum())
624 ast::ExprBox(_, ref contents) => {
625 // Special case for `Box<T>`
626 let box_ty = expr_ty(bcx, expr);
627 let contents_ty = expr_ty(bcx, &**contents);
628 match ty::get(box_ty).sty {
630 trans_uniq_expr(bcx, box_ty, &**contents, contents_ty)
632 _ => bcx.sess().span_bug(expr.span,
633 "expected unique box")
637 ast::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &**lit),
638 ast::ExprBinary(op, ref lhs, ref rhs) => {
639 trans_binary(bcx, expr, op, &**lhs, &**rhs)
641 ast::ExprUnary(op, ref x) => {
642 trans_unary(bcx, expr, op, &**x)
644 ast::ExprAddrOf(_, ref x) => {
646 ast::ExprRepeat(..) | ast::ExprVec(..) => {
647 // Special case for slices.
648 let cleanup_debug_loc =
649 debuginfo::get_cleanup_debug_loc_for_ast_node(x.id, x.span, false);
650 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
651 let datum = unpack_datum!(
652 bcx, tvec::trans_slice_vec(bcx, expr, &**x));
653 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
654 DatumBlock::new(bcx, datum)
657 trans_addr_of(bcx, expr, &**x)
661 ast::ExprCast(ref val, _) => {
662 // Datum output mode means this is a scalar cast:
663 trans_imm_cast(bcx, &**val, expr.id)
666 bcx.tcx().sess.span_bug(
668 format!("trans_rvalue_datum_unadjusted reached \
669 fall-through case: {}",
670 expr.node).as_slice());
675 fn trans_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
677 get_idx: |&'blk ty::ctxt<'tcx>, &[ty::field]| -> uint)
678 -> DatumBlock<'blk, 'tcx, Expr> {
680 let _icx = push_ctxt("trans_rec_field");
682 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
683 let bare_ty = ty::unopen_type(base_datum.ty);
684 let repr = adt::represent_type(bcx.ccx(), bare_ty);
685 with_field_tys(bcx.tcx(), bare_ty, None, |discr, field_tys| {
686 let ix = get_idx(bcx.tcx(), field_tys);
687 let d = base_datum.get_element(
690 |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, ix));
692 if ty::type_is_sized(bcx.tcx(), d.ty) {
693 DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
695 let scratch = rvalue_scratch_datum(bcx, ty::mk_open(bcx.tcx(), d.ty), "");
696 Store(bcx, d.val, get_dataptr(bcx, scratch.val));
697 let info = Load(bcx, get_len(bcx, base_datum.val));
698 Store(bcx, info, get_len(bcx, scratch.val));
700 DatumBlock::new(bcx, scratch.to_expr_datum())
707 /// Translates `base.field`.
708 fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
711 -> DatumBlock<'blk, 'tcx, Expr> {
712 trans_field(bcx, base, |tcx, field_tys| ty::field_idx_strict(tcx, field.name, field_tys))
715 /// Translates `base.<idx>`.
716 fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
719 -> DatumBlock<'blk, 'tcx, Expr> {
720 trans_field(bcx, base, |_, _| idx)
723 fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
724 index_expr: &ast::Expr,
727 method_call: MethodCall)
728 -> DatumBlock<'blk, 'tcx, Expr> {
729 //! Translates `base[idx]`.
731 let _icx = push_ctxt("trans_index");
735 // Check for overloaded index.
736 let method_ty = ccx.tcx()
740 .map(|method| method.ty);
741 let elt_datum = match method_ty {
743 let base_datum = unpack_datum!(bcx, trans(bcx, base));
745 // Translate index expression.
746 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
748 // Overloaded. Evaluate `trans_overloaded_op`, which will
749 // invoke the user's index() method, which basically yields
750 // a `&T` pointer. We can then proceed down the normal
751 // path (below) to dereference that `&T`.
754 trans_overloaded_op(bcx,
758 vec![(ix_datum, idx.id)],
760 let ref_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty)).unwrap();
761 let elt_ty = match ty::deref(ref_ty, true) {
763 bcx.tcx().sess.span_bug(index_expr.span,
764 "index method didn't return a \
765 dereferenceable type?!")
767 Some(elt_tm) => elt_tm.ty,
769 Datum::new(val, elt_ty, LvalueExpr)
772 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
776 // Translate index expression and cast to a suitable LLVM integer.
777 // Rust is less strict than LLVM in this regard.
778 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
779 let ix_val = ix_datum.to_llscalarish(bcx);
780 let ix_size = machine::llbitsize_of_real(bcx.ccx(),
782 let int_size = machine::llbitsize_of_real(bcx.ccx(),
785 if ix_size < int_size {
786 if ty::type_is_signed(expr_ty(bcx, idx)) {
787 SExt(bcx, ix_val, ccx.int_type())
788 } else { ZExt(bcx, ix_val, ccx.int_type()) }
789 } else if ix_size > int_size {
790 Trunc(bcx, ix_val, ccx.int_type())
798 ty::sequence_element_type(bcx.tcx(),
800 base::maybe_name_value(bcx.ccx(), vt.llunit_size, "unit_sz");
802 let (base, len) = base_datum.get_vec_base_and_len(bcx);
804 debug!("trans_index: base {}", bcx.val_to_string(base));
805 debug!("trans_index: len {}", bcx.val_to_string(len));
807 let bounds_check = ICmp(bcx, llvm::IntUGE, ix_val, len);
808 let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
809 let expected = Call(bcx,
811 [bounds_check, C_bool(ccx, false)],
813 bcx = with_cond(bcx, expected, |bcx| {
814 controlflow::trans_fail_bounds_check(bcx,
819 let elt = InBoundsGEP(bcx, base, [ix_val]);
820 let elt = PointerCast(bcx, elt, vt.llunit_ty.ptr_to());
821 Datum::new(elt, vt.unit_ty, LvalueExpr)
825 DatumBlock::new(bcx, elt_datum)
828 fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
829 ref_expr: &ast::Expr,
831 -> DatumBlock<'blk, 'tcx, Expr> {
832 //! Translates a reference to a path.
834 let _icx = push_ctxt("trans_def_lvalue");
836 def::DefFn(..) | def::DefStaticMethod(..) | def::DefMethod(..) |
837 def::DefStruct(_) | def::DefVariant(..) => {
838 trans_def_fn_unadjusted(bcx, ref_expr, def)
840 def::DefStatic(did, _) => {
841 // There are two things that may happen here:
842 // 1) If the static item is defined in this crate, it will be
843 // translated using `get_item_val`, and we return a pointer to
845 // 2) If the static item is defined in another crate then we add
846 // (or reuse) a declaration of an external global, and return a
848 let const_ty = expr_ty(bcx, ref_expr);
850 fn get_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, did: ast::DefId,
851 const_ty: ty::t) -> ValueRef {
852 // For external constants, we don't inline.
853 if did.krate == ast::LOCAL_CRATE {
856 // The LLVM global has the type of its initializer,
857 // which may not be equal to the enum's type for
859 let val = base::get_item_val(bcx.ccx(), did.node);
860 let pty = type_of::type_of(bcx.ccx(), const_ty).ptr_to();
861 PointerCast(bcx, val, pty)
864 base::get_extern_const(bcx.ccx(), did, const_ty)
867 let val = get_val(bcx, did, const_ty);
868 DatumBlock::new(bcx, Datum::new(val, const_ty, LvalueExpr))
870 def::DefConst(did) => {
871 // First, inline any external constants into the local crate so we
872 // can be sure to get the LLVM value corresponding to it.
873 let did = inline::maybe_instantiate_inline(bcx.ccx(), did);
874 if did.krate != ast::LOCAL_CRATE {
875 bcx.tcx().sess.span_bug(ref_expr.span,
876 "cross crate constant could not \
879 let val = base::get_item_val(bcx.ccx(), did.node);
881 // Next, we need to crate a ByRef rvalue datum to return. We can't
882 // use the normal .to_ref_datum() function because the type of
883 // `val` is not actually the same as `const_ty`.
885 // To get around this, we make a custom alloca slot with the
886 // appropriate type (const_ty), and then we cast it to a pointer of
887 // typeof(val), store the value, and then hand this slot over to
888 // the datum infrastructure.
889 let const_ty = expr_ty(bcx, ref_expr);
890 let llty = type_of::type_of(bcx.ccx(), const_ty);
891 let slot = alloca(bcx, llty, "const");
892 let pty = Type::from_ref(unsafe { llvm::LLVMTypeOf(val) }).ptr_to();
893 Store(bcx, val, PointerCast(bcx, slot, pty));
895 let datum = Datum::new(slot, const_ty, Rvalue::new(ByRef));
896 DatumBlock::new(bcx, datum.to_expr_datum())
899 DatumBlock::new(bcx, trans_local_var(bcx, def).to_expr_datum())
904 fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
906 -> Block<'blk, 'tcx> {
908 let _icx = push_ctxt("trans_rvalue_stmt");
910 if bcx.unreachable.get() {
914 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
917 ast::ExprParen(ref e) => {
918 trans_into(bcx, &**e, Ignore)
920 ast::ExprBreak(label_opt) => {
921 controlflow::trans_break(bcx, expr.id, label_opt)
923 ast::ExprAgain(label_opt) => {
924 controlflow::trans_cont(bcx, expr.id, label_opt)
926 ast::ExprRet(ref ex) => {
927 controlflow::trans_ret(bcx, ex.as_ref().map(|e| &**e))
929 ast::ExprWhile(ref cond, ref body, _) => {
930 controlflow::trans_while(bcx, expr.id, &**cond, &**body)
932 ast::ExprForLoop(ref pat, ref head, ref body, _) => {
933 controlflow::trans_for(bcx,
939 ast::ExprLoop(ref body, _) => {
940 controlflow::trans_loop(bcx, expr.id, &**body)
942 ast::ExprAssign(ref dst, ref src) => {
943 let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
944 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &**dst, "assign"));
946 if ty::type_needs_drop(bcx.tcx(), dst_datum.ty) {
947 // If there are destructors involved, make sure we
948 // are copying from an rvalue, since that cannot possible
949 // alias an lvalue. We are concerned about code like:
957 // where e.g. a : Option<Foo> and a.b :
958 // Option<Foo>. In that case, freeing `a` before the
959 // assignment may also free `a.b`!
961 // We could avoid this intermediary with some analysis
962 // to determine whether `dst` may possibly own `src`.
963 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
964 let src_datum = unpack_datum!(
965 bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
966 bcx = glue::drop_ty(bcx,
969 Some(NodeInfo { id: expr.id, span: expr.span }));
970 src_datum.store_to(bcx, dst_datum.val)
972 src_datum.store_to(bcx, dst_datum.val)
975 ast::ExprAssignOp(op, ref dst, ref src) => {
976 trans_assign_op(bcx, expr, op, &**dst, &**src)
978 ast::ExprInlineAsm(ref a) => {
979 asm::trans_inline_asm(bcx, a)
982 bcx.tcx().sess.span_bug(
984 format!("trans_rvalue_stmt_unadjusted reached \
985 fall-through case: {}",
986 expr.node).as_slice());
991 fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
994 -> Block<'blk, 'tcx> {
995 let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
999 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
1002 ast::ExprParen(ref e) => {
1003 trans_into(bcx, &**e, dest)
1005 ast::ExprPath(_) => {
1006 trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
1008 ast::ExprIf(ref cond, ref thn, ref els) => {
1009 controlflow::trans_if(bcx, expr.id, &**cond, &**thn, els.as_ref().map(|e| &**e), dest)
1011 ast::ExprMatch(ref discr, ref arms, _) => {
1012 _match::trans_match(bcx, expr, &**discr, arms.as_slice(), dest)
1014 ast::ExprBlock(ref blk) => {
1015 controlflow::trans_block(bcx, &**blk, dest)
1017 ast::ExprStruct(_, ref fields, ref base) => {
1020 base.as_ref().map(|e| &**e),
1025 ast::ExprTup(ref args) => {
1026 let numbered_fields: Vec<(uint, &ast::Expr)> =
1027 args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
1031 numbered_fields.as_slice(),
1034 Some(NodeInfo { id: expr.id, span: expr.span }))
1036 ast::ExprLit(ref lit) => {
1038 ast::LitStr(ref s, _) => {
1039 tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
1044 .span_bug(expr.span,
1045 "trans_rvalue_dps_unadjusted shouldn't be \
1046 translating this type of literal")
1050 ast::ExprVec(..) | ast::ExprRepeat(..) => {
1051 tvec::trans_fixed_vstore(bcx, expr, dest)
1053 ast::ExprFnBlock(_, ref decl, ref body) |
1054 ast::ExprProc(ref decl, ref body) => {
1055 let expr_ty = expr_ty(bcx, expr);
1056 let store = ty::ty_closure_store(expr_ty);
1057 debug!("translating block function {} with type {}",
1058 expr_to_string(expr), expr_ty.repr(tcx));
1059 closure::trans_expr_fn(bcx, store, &**decl, &**body, expr.id, dest)
1061 ast::ExprUnboxedFn(_, _, ref decl, ref body) => {
1062 closure::trans_unboxed_closure(bcx, &**decl, &**body, expr.id, dest)
1064 ast::ExprCall(ref f, ref args) => {
1065 if bcx.tcx().is_method_call(expr.id) {
1066 trans_overloaded_call(bcx,
1072 callee::trans_call(bcx,
1075 callee::ArgExprs(args.as_slice()),
1079 ast::ExprMethodCall(_, _, ref args) => {
1080 callee::trans_method_call(bcx,
1083 callee::ArgExprs(args.as_slice()),
1086 ast::ExprBinary(_, ref lhs, ref rhs) => {
1087 // if not overloaded, would be RvalueDatumExpr
1088 let lhs = unpack_datum!(bcx, trans(bcx, &**lhs));
1089 let rhs_datum = unpack_datum!(bcx, trans(bcx, &**rhs));
1090 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), lhs,
1091 vec![(rhs_datum, rhs.id)], Some(dest)).bcx
1093 ast::ExprUnary(_, ref subexpr) => {
1094 // if not overloaded, would be RvalueDatumExpr
1095 let arg = unpack_datum!(bcx, trans(bcx, &**subexpr));
1096 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id),
1097 arg, Vec::new(), Some(dest)).bcx
1099 ast::ExprIndex(ref base, ref idx) => {
1100 // if not overloaded, would be RvalueDatumExpr
1101 let base = unpack_datum!(bcx, trans(bcx, &**base));
1102 let idx_datum = unpack_datum!(bcx, trans(bcx, &**idx));
1103 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), base,
1104 vec![(idx_datum, idx.id)], Some(dest)).bcx
1106 ast::ExprCast(ref val, _) => {
1107 // DPS output mode means this is a trait cast:
1108 if ty::type_is_trait(node_id_type(bcx, expr.id)) {
1110 bcx.tcx().object_cast_map.borrow()
1112 .map(|t| (*t).clone())
1115 trait_ref.subst(bcx.tcx(), &bcx.fcx.param_substs.substs);
1116 let datum = unpack_datum!(bcx, trans(bcx, &**val));
1117 meth::trans_trait_cast(bcx, datum, expr.id,
1120 bcx.tcx().sess.span_bug(expr.span,
1121 "expr_cast of non-trait");
1124 ast::ExprAssignOp(op, ref dst, ref src) => {
1125 trans_assign_op(bcx, expr, op, &**dst, &**src)
1128 bcx.tcx().sess.span_bug(
1130 format!("trans_rvalue_dps_unadjusted reached fall-through \
1132 expr.node).as_slice());
1137 fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1138 ref_expr: &ast::Expr,
1141 -> Block<'blk, 'tcx> {
1142 let _icx = push_ctxt("trans_def_dps_unadjusted");
1144 let lldest = match dest {
1145 SaveIn(lldest) => lldest,
1146 Ignore => { return bcx; }
1150 def::DefVariant(tid, vid, _) => {
1151 let variant_info = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
1152 if variant_info.args.len() > 0u {
1154 let llfn = callee::trans_fn_ref(bcx, vid, ExprId(ref_expr.id));
1155 Store(bcx, llfn, lldest);
1159 let ty = expr_ty(bcx, ref_expr);
1160 let repr = adt::represent_type(bcx.ccx(), ty);
1161 adt::trans_set_discr(bcx, &*repr, lldest,
1162 variant_info.disr_val);
1166 def::DefStruct(_) => {
1167 let ty = expr_ty(bcx, ref_expr);
1168 match ty::get(ty).sty {
1169 ty::ty_struct(did, _) if ty::has_dtor(bcx.tcx(), did) => {
1170 let repr = adt::represent_type(bcx.ccx(), ty);
1171 adt::trans_set_discr(bcx, &*repr, lldest, 0);
1178 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1179 "Non-DPS def {} referened by {}",
1180 def, bcx.node_id_to_string(ref_expr.id)).as_slice());
1185 fn trans_def_fn_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1186 ref_expr: &ast::Expr,
1188 -> DatumBlock<'blk, 'tcx, Expr> {
1189 let _icx = push_ctxt("trans_def_datum_unadjusted");
1191 let llfn = match def {
1192 def::DefFn(did, _, _) |
1193 def::DefStruct(did) | def::DefVariant(_, did, _) |
1194 def::DefStaticMethod(did, def::FromImpl(_), _) |
1195 def::DefMethod(did, _, def::FromImpl(_)) => {
1196 callee::trans_fn_ref(bcx, did, ExprId(ref_expr.id))
1198 def::DefStaticMethod(impl_did, def::FromTrait(trait_did), _) |
1199 def::DefMethod(impl_did, _, def::FromTrait(trait_did)) => {
1200 meth::trans_static_method_callee(bcx, impl_did,
1201 trait_did, ref_expr.id)
1204 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1205 "trans_def_fn_unadjusted invoked on: {} for {}",
1207 ref_expr.repr(bcx.tcx())).as_slice());
1211 let fn_ty = expr_ty(bcx, ref_expr);
1212 DatumBlock::new(bcx, Datum::new(llfn, fn_ty, RvalueExpr(Rvalue::new(ByValue))))
1215 pub fn trans_local_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1219 * Translates a reference to a local variable or argument.
1220 * This always results in an lvalue datum.
1223 let _icx = push_ctxt("trans_local_var");
1226 def::DefUpvar(nid, _, _) => {
1227 // Can't move upvars, so this is never a ZeroMemLastUse.
1228 let local_ty = node_id_type(bcx, nid);
1229 match bcx.fcx.llupvars.borrow().find(&nid) {
1230 Some(&val) => Datum::new(val, local_ty, Lvalue),
1232 bcx.sess().bug(format!(
1233 "trans_local_var: no llval for upvar {} found",
1238 def::DefLocal(nid) => {
1239 let datum = match bcx.fcx.lllocals.borrow().find(&nid) {
1242 bcx.sess().bug(format!(
1243 "trans_local_var: no datum for local/arg {} found",
1247 debug!("take_local(nid={}, v={}, ty={})",
1248 nid, bcx.val_to_string(datum.val), bcx.ty_to_string(datum.ty));
1252 bcx.sess().unimpl(format!(
1253 "unsupported def type in trans_local_var: {}",
1259 pub fn with_field_tys<R>(tcx: &ty::ctxt,
1261 node_id_opt: Option<ast::NodeId>,
1262 op: |ty::Disr, (&[ty::field])| -> R)
1265 * Helper for enumerating the field types of structs, enums, or records.
1266 * The optional node ID here is the node ID of the path identifying the enum
1267 * variant in use. If none, this cannot possibly an enum variant (so, if it
1268 * is and `node_id_opt` is none, this function panics).
1271 match ty::get(ty).sty {
1272 ty::ty_struct(did, ref substs) => {
1273 op(0, struct_fields(tcx, did, substs).as_slice())
1276 ty::ty_tup(ref v) => {
1277 op(0, tup_fields(v.as_slice()).as_slice())
1280 ty::ty_enum(_, ref substs) => {
1281 // We want the *variant* ID here, not the enum ID.
1284 tcx.sess.bug(format!(
1285 "cannot get field types from the enum type {} \
1287 ty.repr(tcx)).as_slice());
1290 let def = tcx.def_map.borrow().get_copy(&node_id);
1292 def::DefVariant(enum_id, variant_id, _) => {
1293 let variant_info = ty::enum_variant_with_id(
1294 tcx, enum_id, variant_id);
1295 op(variant_info.disr_val,
1301 tcx.sess.bug("resolve didn't map this expr to a \
1310 tcx.sess.bug(format!(
1311 "cannot get field types from the type {}",
1312 ty.repr(tcx)).as_slice());
1317 fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1318 fields: &[ast::Field],
1319 base: Option<&ast::Expr>,
1320 expr_span: codemap::Span,
1321 expr_id: ast::NodeId,
1322 dest: Dest) -> Block<'blk, 'tcx> {
1323 let _icx = push_ctxt("trans_rec");
1325 let ty = node_id_type(bcx, expr_id);
1326 let tcx = bcx.tcx();
1327 with_field_tys(tcx, ty, Some(expr_id), |discr, field_tys| {
1328 let mut need_base = Vec::from_elem(field_tys.len(), true);
1330 let numbered_fields = fields.iter().map(|field| {
1332 field_tys.iter().position(|field_ty|
1333 field_ty.name == field.ident.node.name);
1336 *need_base.get_mut(i) = false;
1340 tcx.sess.span_bug(field.span,
1341 "Couldn't find field in struct type")
1344 }).collect::<Vec<_>>();
1345 let optbase = match base {
1346 Some(base_expr) => {
1347 let mut leftovers = Vec::new();
1348 for (i, b) in need_base.iter().enumerate() {
1350 leftovers.push((i, field_tys[i].mt.ty))
1353 Some(StructBaseInfo {expr: base_expr,
1354 fields: leftovers })
1357 if need_base.iter().any(|b| *b) {
1358 tcx.sess.span_bug(expr_span, "missing fields and no base expr")
1367 numbered_fields.as_slice(),
1370 Some(NodeInfo { id: expr_id, span: expr_span }))
1375 * Information that `trans_adt` needs in order to fill in the fields
1376 * of a struct copied from a base struct (e.g., from an expression
1377 * like `Foo { a: b, ..base }`.
1379 * Note that `fields` may be empty; the base expression must always be
1380 * evaluated for side-effects.
1382 pub struct StructBaseInfo<'a> {
1383 /// The base expression; will be evaluated after all explicit fields.
1384 expr: &'a ast::Expr,
1385 /// The indices of fields to copy paired with their types.
1386 fields: Vec<(uint, ty::t)>
1390 * Constructs an ADT instance:
1392 * - `fields` should be a list of field indices paired with the
1393 * expression to store into that field. The initializers will be
1394 * evaluated in the order specified by `fields`.
1396 * - `optbase` contains information on the base struct (if any) from
1397 * which remaining fields are copied; see comments on `StructBaseInfo`.
1399 pub fn trans_adt<'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1402 fields: &[(uint, &ast::Expr)],
1403 optbase: Option<StructBaseInfo>,
1405 source_location: Option<NodeInfo>)
1406 -> Block<'blk, 'tcx> {
1407 let _icx = push_ctxt("trans_adt");
1409 let repr = adt::represent_type(bcx.ccx(), ty);
1411 match source_location {
1412 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1418 // If we don't care about the result, just make a
1419 // temporary stack slot
1420 let addr = match dest {
1422 Ignore => alloc_ty(bcx, ty, "temp"),
1425 // This scope holds intermediates that must be cleaned should
1426 // panic occur before the ADT as a whole is ready.
1427 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1429 // First we trans the base, if we have one, to the dest
1430 for base in optbase.iter() {
1431 assert_eq!(discr, 0);
1433 match ty::expr_kind(bcx.tcx(), &*base.expr) {
1434 ty::RvalueDpsExpr | ty::RvalueDatumExpr if !ty::type_needs_drop(bcx.tcx(), ty) => {
1435 bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
1437 ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr"),
1439 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
1440 for &(i, t) in base.fields.iter() {
1441 let datum = base_datum.get_element(
1442 bcx, t, |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, i));
1443 assert!(ty::type_is_sized(bcx.tcx(), datum.ty));
1444 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1445 bcx = datum.store_to(bcx, dest);
1451 match source_location {
1452 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1458 // Now, we just overwrite the fields we've explicitly specified
1459 for &(i, ref e) in fields.iter() {
1460 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1461 let e_ty = expr_ty_adjusted(bcx, &**e);
1462 bcx = trans_into(bcx, &**e, SaveIn(dest));
1463 let scope = cleanup::CustomScope(custom_cleanup_scope);
1464 fcx.schedule_lifetime_end(scope, dest);
1465 fcx.schedule_drop_mem(scope, dest, e_ty);
1468 adt::trans_set_discr(bcx, &*repr, addr, discr);
1470 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1472 // If we don't care about the result drop the temporary we made
1476 bcx = glue::drop_ty(bcx, addr, ty, source_location);
1477 base::call_lifetime_end(bcx, addr);
1484 fn trans_immediate_lit<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1487 -> DatumBlock<'blk, 'tcx, Expr> {
1488 // must not be a string constant, that is a RvalueDpsExpr
1489 let _icx = push_ctxt("trans_immediate_lit");
1490 let ty = expr_ty(bcx, expr);
1491 let v = consts::const_lit(bcx.ccx(), expr, lit);
1492 immediate_rvalue_bcx(bcx, v, ty).to_expr_datumblock()
1495 fn trans_unary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1498 sub_expr: &ast::Expr)
1499 -> DatumBlock<'blk, 'tcx, Expr> {
1500 let ccx = bcx.ccx();
1502 let _icx = push_ctxt("trans_unary_datum");
1504 let method_call = MethodCall::expr(expr.id);
1506 // The only overloaded operator that is translated to a datum
1507 // is an overloaded deref, since it is always yields a `&T`.
1508 // Otherwise, we should be in the RvalueDpsExpr path.
1510 op == ast::UnDeref ||
1511 !ccx.tcx().method_map.borrow().contains_key(&method_call));
1513 let un_ty = expr_ty(bcx, expr);
1517 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1518 let llresult = Not(bcx, datum.to_llscalarish(bcx));
1519 immediate_rvalue_bcx(bcx, llresult, un_ty).to_expr_datumblock()
1522 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1523 let val = datum.to_llscalarish(bcx);
1525 if ty::type_is_fp(un_ty) {
1531 immediate_rvalue_bcx(bcx, llneg, un_ty).to_expr_datumblock()
1534 trans_uniq_expr(bcx, un_ty, sub_expr, expr_ty(bcx, sub_expr))
1537 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1538 deref_once(bcx, expr, datum, method_call)
1543 fn trans_uniq_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1545 contents: &ast::Expr,
1547 -> DatumBlock<'blk, 'tcx, Expr> {
1548 let _icx = push_ctxt("trans_uniq_expr");
1550 assert!(ty::type_is_sized(bcx.tcx(), contents_ty));
1551 let llty = type_of::type_of(bcx.ccx(), contents_ty);
1552 let size = llsize_of(bcx.ccx(), llty);
1553 let align = C_uint(bcx.ccx(), type_of::align_of(bcx.ccx(), contents_ty));
1554 let llty_ptr = llty.ptr_to();
1555 let Result { bcx, val } = malloc_raw_dyn(bcx, llty_ptr, box_ty, size, align);
1556 // Unique boxes do not allocate for zero-size types. The standard library
1557 // may assume that `free` is never called on the pointer returned for
1558 // `Box<ZeroSizeType>`.
1559 let bcx = if llsize_of_alloc(bcx.ccx(), llty) == 0 {
1560 trans_into(bcx, contents, SaveIn(val))
1562 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1563 fcx.schedule_free_value(cleanup::CustomScope(custom_cleanup_scope),
1564 val, cleanup::HeapExchange, contents_ty);
1565 let bcx = trans_into(bcx, contents, SaveIn(val));
1566 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1569 immediate_rvalue_bcx(bcx, val, box_ty).to_expr_datumblock()
1572 fn trans_addr_of<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1574 subexpr: &ast::Expr)
1575 -> DatumBlock<'blk, 'tcx, Expr> {
1576 let _icx = push_ctxt("trans_addr_of");
1578 let sub_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, subexpr, "addr_of"));
1579 match ty::get(sub_datum.ty).sty {
1581 // Opened DST value, close to a fat pointer
1582 debug!("Closing fat pointer {}", bcx.ty_to_string(sub_datum.ty));
1584 let scratch = rvalue_scratch_datum(bcx,
1585 ty::close_type(bcx.tcx(), sub_datum.ty),
1587 let base = Load(bcx, get_dataptr(bcx, sub_datum.val));
1588 Store(bcx, base, get_dataptr(bcx, scratch.val));
1590 let len = Load(bcx, get_len(bcx, sub_datum.val));
1591 Store(bcx, len, get_len(bcx, scratch.val));
1593 DatumBlock::new(bcx, scratch.to_expr_datum())
1596 // Sized value, ref to a thin pointer
1597 let ty = expr_ty(bcx, expr);
1598 immediate_rvalue_bcx(bcx, sub_datum.val, ty).to_expr_datumblock()
1603 // Important to get types for both lhs and rhs, because one might be _|_
1604 // and the other not.
1605 fn trans_eager_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1606 binop_expr: &ast::Expr,
1613 -> DatumBlock<'blk, 'tcx, Expr> {
1614 let _icx = push_ctxt("trans_eager_binop");
1616 let tcx = bcx.tcx();
1617 let is_simd = ty::type_is_simd(tcx, lhs_t);
1619 if is_simd { ty::simd_type(tcx, lhs_t) }
1622 let is_float = ty::type_is_fp(intype);
1623 let is_signed = ty::type_is_signed(intype);
1625 let rhs = base::cast_shift_expr_rhs(bcx, op, lhs, rhs);
1628 let val = match op {
1630 if is_float { FAdd(bcx, lhs, rhs) }
1631 else { Add(bcx, lhs, rhs) }
1634 if is_float { FSub(bcx, lhs, rhs) }
1635 else { Sub(bcx, lhs, rhs) }
1638 if is_float { FMul(bcx, lhs, rhs) }
1639 else { Mul(bcx, lhs, rhs) }
1645 // Only zero-check integers; fp /0 is NaN
1646 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1647 op, lhs, rhs, rhs_t);
1659 // Only zero-check integers; fp %0 is NaN
1660 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1661 op, lhs, rhs, rhs_t);
1669 ast::BiBitOr => Or(bcx, lhs, rhs),
1670 ast::BiBitAnd => And(bcx, lhs, rhs),
1671 ast::BiBitXor => Xor(bcx, lhs, rhs),
1672 ast::BiShl => Shl(bcx, lhs, rhs),
1676 } else { LShr(bcx, lhs, rhs) }
1678 ast::BiEq | ast::BiNe | ast::BiLt | ast::BiGe | ast::BiLe | ast::BiGt => {
1679 if ty::type_is_scalar(rhs_t) {
1680 unpack_result!(bcx, base::compare_scalar_types(bcx, lhs, rhs, rhs_t, op))
1682 base::compare_simd_types(bcx, lhs, rhs, intype, ty::simd_size(tcx, lhs_t), op)
1684 bcx.tcx().sess.span_bug(binop_expr.span, "comparison operator unsupported for type")
1688 bcx.tcx().sess.span_bug(binop_expr.span, "unexpected binop");
1692 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1695 // refinement types would obviate the need for this
1696 enum lazy_binop_ty {
1701 fn trans_lazy_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1702 binop_expr: &ast::Expr,
1706 -> DatumBlock<'blk, 'tcx, Expr> {
1707 let _icx = push_ctxt("trans_lazy_binop");
1708 let binop_ty = expr_ty(bcx, binop_expr);
1711 let DatumBlock {bcx: past_lhs, datum: lhs} = trans(bcx, a);
1712 let lhs = lhs.to_llscalarish(past_lhs);
1714 if past_lhs.unreachable.get() {
1715 return immediate_rvalue_bcx(past_lhs, lhs, binop_ty).to_expr_datumblock();
1718 let join = fcx.new_id_block("join", binop_expr.id);
1719 let before_rhs = fcx.new_id_block("before_rhs", b.id);
1722 lazy_and => CondBr(past_lhs, lhs, before_rhs.llbb, join.llbb),
1723 lazy_or => CondBr(past_lhs, lhs, join.llbb, before_rhs.llbb)
1726 let DatumBlock {bcx: past_rhs, datum: rhs} = trans(before_rhs, b);
1727 let rhs = rhs.to_llscalarish(past_rhs);
1729 if past_rhs.unreachable.get() {
1730 return immediate_rvalue_bcx(join, lhs, binop_ty).to_expr_datumblock();
1733 Br(past_rhs, join.llbb);
1734 let phi = Phi(join, Type::i1(bcx.ccx()), [lhs, rhs],
1735 [past_lhs.llbb, past_rhs.llbb]);
1737 return immediate_rvalue_bcx(join, phi, binop_ty).to_expr_datumblock();
1740 fn trans_binary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1745 -> DatumBlock<'blk, 'tcx, Expr> {
1746 let _icx = push_ctxt("trans_binary");
1747 let ccx = bcx.ccx();
1749 // if overloaded, would be RvalueDpsExpr
1750 assert!(!ccx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
1754 trans_lazy_binop(bcx, expr, lazy_and, lhs, rhs)
1757 trans_lazy_binop(bcx, expr, lazy_or, lhs, rhs)
1761 let lhs_datum = unpack_datum!(bcx, trans(bcx, lhs));
1762 let rhs_datum = unpack_datum!(bcx, trans(bcx, rhs));
1763 let binop_ty = expr_ty(bcx, expr);
1765 debug!("trans_binary (expr {}): lhs_datum={}",
1767 lhs_datum.to_string(ccx));
1768 let lhs_ty = lhs_datum.ty;
1769 let lhs = lhs_datum.to_llscalarish(bcx);
1771 debug!("trans_binary (expr {}): rhs_datum={}",
1773 rhs_datum.to_string(ccx));
1774 let rhs_ty = rhs_datum.ty;
1775 let rhs = rhs_datum.to_llscalarish(bcx);
1776 trans_eager_binop(bcx, expr, binop_ty, op,
1777 lhs_ty, lhs, rhs_ty, rhs)
1782 fn trans_overloaded_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1784 method_call: MethodCall,
1786 rhs: Vec<(Datum<Expr>, ast::NodeId)>,
1788 -> Result<'blk, 'tcx> {
1789 let method_ty = (*bcx.tcx().method_map.borrow())[method_call].ty;
1790 callee::trans_call_inner(bcx,
1791 Some(expr_info(expr)),
1792 monomorphize_type(bcx, method_ty),
1793 |bcx, arg_cleanup_scope| {
1794 meth::trans_method_callee(bcx,
1799 callee::ArgOverloadedOp(lhs, rhs),
1803 fn trans_overloaded_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1805 callee: &'a ast::Expr,
1806 args: &'a [P<ast::Expr>],
1808 -> Block<'blk, 'tcx> {
1809 let method_call = MethodCall::expr(expr.id);
1810 let method_type = (*bcx.tcx()
1812 .borrow())[method_call]
1814 let mut all_args = vec!(callee);
1815 all_args.extend(args.iter().map(|e| &**e));
1817 callee::trans_call_inner(bcx,
1818 Some(expr_info(expr)),
1819 monomorphize_type(bcx,
1821 |bcx, arg_cleanup_scope| {
1822 meth::trans_method_callee(
1828 callee::ArgOverloadedCall(all_args),
1833 fn int_cast(bcx: Block,
1839 let _icx = push_ctxt("int_cast");
1841 let srcsz = llvm::LLVMGetIntTypeWidth(llsrctype.to_ref());
1842 let dstsz = llvm::LLVMGetIntTypeWidth(lldsttype.to_ref());
1843 return if dstsz == srcsz {
1844 BitCast(bcx, llsrc, lldsttype)
1845 } else if srcsz > dstsz {
1846 TruncOrBitCast(bcx, llsrc, lldsttype)
1848 SExtOrBitCast(bcx, llsrc, lldsttype)
1850 ZExtOrBitCast(bcx, llsrc, lldsttype)
1855 fn float_cast(bcx: Block,
1860 let _icx = push_ctxt("float_cast");
1861 let srcsz = llsrctype.float_width();
1862 let dstsz = lldsttype.float_width();
1863 return if dstsz > srcsz {
1864 FPExt(bcx, llsrc, lldsttype)
1865 } else if srcsz > dstsz {
1866 FPTrunc(bcx, llsrc, lldsttype)
1870 #[deriving(PartialEq, Show)]
1871 pub enum cast_kind {
1879 pub fn cast_type_kind(tcx: &ty::ctxt, t: ty::t) -> cast_kind {
1880 match ty::get(t).sty {
1881 ty::ty_char => cast_integral,
1882 ty::ty_float(..) => cast_float,
1883 ty::ty_rptr(_, mt) | ty::ty_ptr(mt) => {
1884 if ty::type_is_sized(tcx, mt.ty) {
1890 ty::ty_bare_fn(..) => cast_pointer,
1891 ty::ty_int(..) => cast_integral,
1892 ty::ty_uint(..) => cast_integral,
1893 ty::ty_bool => cast_integral,
1894 ty::ty_enum(..) => cast_enum,
1899 fn cast_is_noop(t_in: ty::t, t_out: ty::t) -> bool {
1900 match (ty::deref(t_in, true), ty::deref(t_out, true)) {
1901 (Some(ty::mt{ ty: t_in, .. }), Some(ty::mt{ ty: t_out, .. })) => {
1908 fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1911 -> DatumBlock<'blk, 'tcx, Expr> {
1912 let _icx = push_ctxt("trans_cast");
1914 let ccx = bcx.ccx();
1916 let t_in = expr_ty(bcx, expr);
1917 let t_out = node_id_type(bcx, id);
1918 let k_in = cast_type_kind(bcx.tcx(), t_in);
1919 let k_out = cast_type_kind(bcx.tcx(), t_out);
1920 let s_in = k_in == cast_integral && ty::type_is_signed(t_in);
1921 let ll_t_in = type_of::arg_type_of(ccx, t_in);
1922 let ll_t_out = type_of::arg_type_of(ccx, t_out);
1924 // Convert the value to be cast into a ValueRef, either by-ref or
1925 // by-value as appropriate given its type:
1926 let mut datum = unpack_datum!(bcx, trans(bcx, expr));
1928 if cast_is_noop(datum.ty, t_out) {
1930 return DatumBlock::new(bcx, datum);
1933 let newval = match (k_in, k_out) {
1934 (cast_integral, cast_integral) => {
1935 let llexpr = datum.to_llscalarish(bcx);
1936 int_cast(bcx, ll_t_out, ll_t_in, llexpr, s_in)
1938 (cast_float, cast_float) => {
1939 let llexpr = datum.to_llscalarish(bcx);
1940 float_cast(bcx, ll_t_out, ll_t_in, llexpr)
1942 (cast_integral, cast_float) => {
1943 let llexpr = datum.to_llscalarish(bcx);
1945 SIToFP(bcx, llexpr, ll_t_out)
1946 } else { UIToFP(bcx, llexpr, ll_t_out) }
1948 (cast_float, cast_integral) => {
1949 let llexpr = datum.to_llscalarish(bcx);
1950 if ty::type_is_signed(t_out) {
1951 FPToSI(bcx, llexpr, ll_t_out)
1952 } else { FPToUI(bcx, llexpr, ll_t_out) }
1954 (cast_integral, cast_pointer) => {
1955 let llexpr = datum.to_llscalarish(bcx);
1956 IntToPtr(bcx, llexpr, ll_t_out)
1958 (cast_pointer, cast_integral) => {
1959 let llexpr = datum.to_llscalarish(bcx);
1960 PtrToInt(bcx, llexpr, ll_t_out)
1962 (cast_pointer, cast_pointer) => {
1963 let llexpr = datum.to_llscalarish(bcx);
1964 PointerCast(bcx, llexpr, ll_t_out)
1966 (cast_enum, cast_integral) |
1967 (cast_enum, cast_float) => {
1969 let repr = adt::represent_type(ccx, t_in);
1970 let datum = unpack_datum!(
1971 bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
1972 let llexpr_ptr = datum.to_llref();
1974 adt::trans_get_discr(bcx, &*repr, llexpr_ptr, Some(Type::i64(ccx)));
1976 cast_integral => int_cast(bcx, ll_t_out,
1977 val_ty(lldiscrim_a),
1979 cast_float => SIToFP(bcx, lldiscrim_a, ll_t_out),
1981 ccx.sess().bug(format!("translating unsupported cast: \
1982 {} ({}) -> {} ({})",
1983 t_in.repr(bcx.tcx()),
1985 t_out.repr(bcx.tcx()),
1990 _ => ccx.sess().bug(format!("translating unsupported cast: \
1991 {} ({}) -> {} ({})",
1992 t_in.repr(bcx.tcx()),
1994 t_out.repr(bcx.tcx()),
1997 return immediate_rvalue_bcx(bcx, newval, t_out).to_expr_datumblock();
2000 fn trans_assign_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2005 -> Block<'blk, 'tcx> {
2006 let _icx = push_ctxt("trans_assign_op");
2009 debug!("trans_assign_op(expr={})", bcx.expr_to_string(expr));
2011 // User-defined operator methods cannot be used with `+=` etc right now
2012 assert!(!bcx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
2014 // Evaluate LHS (destination), which should be an lvalue
2015 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, dst, "assign_op"));
2016 assert!(!ty::type_needs_drop(bcx.tcx(), dst_datum.ty));
2017 let dst_ty = dst_datum.ty;
2018 let dst = load_ty(bcx, dst_datum.val, dst_datum.ty);
2021 let rhs_datum = unpack_datum!(bcx, trans(bcx, &*src));
2022 let rhs_ty = rhs_datum.ty;
2023 let rhs = rhs_datum.to_llscalarish(bcx);
2025 // Perform computation and store the result
2026 let result_datum = unpack_datum!(
2027 bcx, trans_eager_binop(bcx, expr, dst_datum.ty, op,
2028 dst_ty, dst, rhs_ty, rhs));
2029 return result_datum.store_to(bcx, dst_datum.val);
2032 fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2035 -> DatumBlock<'blk, 'tcx, Expr> {
2038 // Ensure cleanup of `datum` if not already scheduled and obtain
2039 // a "by ref" pointer.
2040 let lv_datum = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "autoref", expr.id));
2042 // Compute final type. Note that we are loose with the region and
2043 // mutability, since those things don't matter in trans.
2044 let referent_ty = lv_datum.ty;
2045 let ptr_ty = ty::mk_imm_rptr(bcx.tcx(), ty::ReStatic, referent_ty);
2048 let llref = lv_datum.to_llref();
2050 // Construct the resulting datum, using what was the "by ref"
2051 // ValueRef of type `referent_ty` to be the "by value" ValueRef
2052 // of type `&referent_ty`.
2053 DatumBlock::new(bcx, Datum::new(llref, ptr_ty, RvalueExpr(Rvalue::new(ByValue))))
2056 fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2060 -> DatumBlock<'blk, 'tcx, Expr> {
2062 let mut datum = datum;
2063 for i in range(0, times) {
2064 let method_call = MethodCall::autoderef(expr.id, i);
2065 datum = unpack_datum!(bcx, deref_once(bcx, expr, datum, method_call));
2067 DatumBlock { bcx: bcx, datum: datum }
2070 fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2073 method_call: MethodCall)
2074 -> DatumBlock<'blk, 'tcx, Expr> {
2075 let ccx = bcx.ccx();
2077 debug!("deref_once(expr={}, datum={}, method_call={})",
2078 expr.repr(bcx.tcx()),
2079 datum.to_string(ccx),
2084 // Check for overloaded deref.
2085 let method_ty = ccx.tcx().method_map.borrow()
2086 .find(&method_call).map(|method| method.ty);
2087 let datum = match method_ty {
2088 Some(method_ty) => {
2089 // Overloaded. Evaluate `trans_overloaded_op`, which will
2090 // invoke the user's deref() method, which basically
2091 // converts from the `Smaht<T>` pointer that we have into
2092 // a `&T` pointer. We can then proceed down the normal
2093 // path (below) to dereference that `&T`.
2094 let datum = match method_call.adjustment {
2095 // Always perform an AutoPtr when applying an overloaded auto-deref
2096 typeck::AutoDeref(_) => unpack_datum!(bcx, auto_ref(bcx, datum, expr)),
2100 let ref_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty)).unwrap();
2101 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_deref");
2103 unpack_result!(bcx, trans_overloaded_op(bcx, expr, method_call,
2104 datum, Vec::new(), Some(SaveIn(scratch.val))));
2105 scratch.to_expr_datum()
2108 // Not overloaded. We already have a pointer we know how to deref.
2113 let r = match ty::get(datum.ty).sty {
2114 ty::ty_uniq(content_ty) => {
2115 if ty::type_is_sized(bcx.tcx(), content_ty) {
2116 deref_owned_pointer(bcx, expr, datum, content_ty)
2118 // A fat pointer and an opened DST value have the same
2119 // representation just different types. Since there is no
2120 // temporary for `*e` here (because it is unsized), we cannot
2121 // emulate the sized object code path for running drop glue and
2122 // free. Instead, we schedule cleanup for `e`, turning it into
2124 let datum = unpack_datum!(
2125 bcx, datum.to_lvalue_datum(bcx, "deref", expr.id));
2127 let datum = Datum::new(datum.val, ty::mk_open(bcx.tcx(), content_ty), LvalueExpr);
2128 DatumBlock::new(bcx, datum)
2132 ty::ty_ptr(ty::mt { ty: content_ty, .. }) |
2133 ty::ty_rptr(_, ty::mt { ty: content_ty, .. }) => {
2134 if ty::type_is_sized(bcx.tcx(), content_ty) {
2135 let ptr = datum.to_llscalarish(bcx);
2137 // Always generate an lvalue datum, even if datum.mode is
2138 // an rvalue. This is because datum.mode is only an
2139 // rvalue for non-owning pointers like &T or *T, in which
2140 // case cleanup *is* scheduled elsewhere, by the true
2141 // owner (or, in the case of *T, by the user).
2142 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr))
2144 // A fat pointer and an opened DST value have the same representation
2145 // just different types.
2146 DatumBlock::new(bcx, Datum::new(datum.val,
2147 ty::mk_open(bcx.tcx(), content_ty),
2153 bcx.tcx().sess.span_bug(
2155 format!("deref invoked on expr of illegal type {}",
2156 datum.ty.repr(bcx.tcx())).as_slice());
2160 debug!("deref_once(expr={}, method_call={}, result={})",
2161 expr.id, method_call, r.datum.to_string(ccx));
2165 fn deref_owned_pointer<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2169 -> DatumBlock<'blk, 'tcx, Expr> {
2171 * We microoptimize derefs of owned pointers a bit here.
2172 * Basically, the idea is to make the deref of an rvalue
2173 * result in an rvalue. This helps to avoid intermediate stack
2174 * slots in the resulting LLVM. The idea here is that, if the
2175 * `Box<T>` pointer is an rvalue, then we can schedule a *shallow*
2176 * free of the `Box<T>` pointer, and then return a ByRef rvalue
2177 * into the pointer. Because the free is shallow, it is legit
2178 * to return an rvalue, because we know that the contents are
2179 * not yet scheduled to be freed. The language rules ensure that the
2180 * contents will be used (or moved) before the free occurs.
2184 RvalueExpr(Rvalue { mode: ByRef }) => {
2185 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2186 let ptr = Load(bcx, datum.val);
2187 if !type_is_zero_size(bcx.ccx(), content_ty) {
2188 bcx.fcx.schedule_free_value(scope, ptr, cleanup::HeapExchange, content_ty);
2191 RvalueExpr(Rvalue { mode: ByValue }) => {
2192 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2193 if !type_is_zero_size(bcx.ccx(), content_ty) {
2194 bcx.fcx.schedule_free_value(scope, datum.val, cleanup::HeapExchange,
2201 // If we had an rvalue in, we produce an rvalue out.
2202 let (llptr, kind) = match datum.kind {
2204 (Load(bcx, datum.val), LvalueExpr)
2206 RvalueExpr(Rvalue { mode: ByRef }) => {
2207 (Load(bcx, datum.val), RvalueExpr(Rvalue::new(ByRef)))
2209 RvalueExpr(Rvalue { mode: ByValue }) => {
2210 (datum.val, RvalueExpr(Rvalue::new(ByRef)))
2214 let datum = Datum { ty: content_ty, val: llptr, kind: kind };
2215 DatumBlock { bcx: bcx, datum: datum }