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 //! Public entry points:
15 //! - `trans_into(bcx, expr, dest) -> bcx`: evaluates an expression,
16 //! storing the result into `dest`. This is the preferred form, if you
19 //! - `trans(bcx, expr) -> DatumBlock`: evaluates an expression, yielding
20 //! `Datum` with the result. You can then store the datum, inspect
21 //! the value, etc. This may introduce temporaries if the datum is a
24 //! - `trans_to_lvalue(bcx, expr, "...") -> DatumBlock`: evaluates an
25 //! expression and ensures that the result has a cleanup associated with it,
26 //! creating a temporary stack slot if necessary.
28 //! - `trans_local_var -> Datum`: looks up a local variable or upvar.
30 //! See doc.rs for more comments.
32 #![allow(non_camel_case_types)]
34 pub use self::cast_kind::*;
35 pub use self::Dest::*;
36 use self::lazy_binop_ty::*;
39 use llvm::{mod, ValueRef};
41 use middle::mem_categorization::Typer;
42 use middle::subst::{mod, Subst};
43 use trans::{_match, adt, asm, base, callee, closure, consts, controlflow};
44 use trans::{debuginfo, glue, machine, meth, inline, tvec, type_of};
47 use trans::cleanup::{mod, CleanupMethods};
50 use middle::ty::{mod, struct_fields, tup_fields};
51 use middle::ty::{AdjustDerefRef, AdjustAddEnv, AutoUnsafe, AutoPtr, Ty};
52 use middle::typeck::{mod, MethodCall};
53 use util::common::indenter;
54 use util::ppaux::Repr;
55 use trans::machine::{llsize_of, llsize_of_alloc};
56 use trans::type_::Type;
58 use syntax::{ast, ast_util, codemap};
59 use syntax::print::pprust::{expr_to_string};
65 // These are passed around by the code generating functions to track the
66 // destination of a computation's value.
68 #[deriving(PartialEq)]
75 pub fn to_string(&self, ccx: &CrateContext) -> String {
77 SaveIn(v) => format!("SaveIn({})", ccx.tn().val_to_string(v)),
78 Ignore => "Ignore".to_string()
83 /// This function is equivalent to `trans(bcx, expr).store_to_dest(dest)` but it may generate
84 /// better optimized LLVM code.
85 pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
88 -> Block<'blk, 'tcx> {
91 if bcx.tcx().adjustments.borrow().contains_key(&expr.id) {
92 // use trans, which may be less efficient but
93 // which will perform the adjustments:
94 let datum = unpack_datum!(bcx, trans(bcx, expr));
95 return datum.store_to_dest(bcx, dest, expr.id)
98 debug!("trans_into() expr={}", expr.repr(bcx.tcx()));
100 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(expr.id,
103 bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
105 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
106 let kind = ty::expr_kind(bcx.tcx(), expr);
108 ty::LvalueExpr | ty::RvalueDatumExpr => {
109 trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
111 ty::RvalueDpsExpr => {
112 trans_rvalue_dps_unadjusted(bcx, expr, dest)
114 ty::RvalueStmtExpr => {
115 trans_rvalue_stmt_unadjusted(bcx, expr)
119 bcx.fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id)
122 /// Translates an expression, returning a datum (and new block) encapsulating the result. When
123 /// possible, it is preferred to use `trans_into`, as that may avoid creating a temporary on the
125 pub fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
127 -> DatumBlock<'blk, 'tcx, Expr> {
128 debug!("trans(expr={})", bcx.expr_to_string(expr));
133 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(expr.id,
136 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
137 let datum = unpack_datum!(bcx, trans_unadjusted(bcx, expr));
138 let datum = unpack_datum!(bcx, apply_adjustments(bcx, expr, datum));
139 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id);
140 return DatumBlock::new(bcx, datum);
143 pub fn get_len(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
144 GEPi(bcx, fat_ptr, &[0u, abi::FAT_PTR_EXTRA])
147 pub fn get_dataptr(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
148 GEPi(bcx, fat_ptr, &[0u, abi::FAT_PTR_ADDR])
151 /// Helper for trans that apply adjustments from `expr` to `datum`, which should be the unadjusted
152 /// translation of `expr`.
153 fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
155 datum: Datum<'tcx, Expr>)
156 -> DatumBlock<'blk, 'tcx, Expr> {
158 let mut datum = datum;
159 let adjustment = match bcx.tcx().adjustments.borrow().get(&expr.id).cloned() {
161 return DatumBlock::new(bcx, datum);
165 debug!("unadjusted datum for expr {}: {}, adjustment={}",
166 expr.repr(bcx.tcx()),
167 datum.to_string(bcx.ccx()),
168 adjustment.repr(bcx.tcx()));
170 AdjustAddEnv(..) => {
171 datum = unpack_datum!(bcx, add_env(bcx, expr, datum));
173 AdjustDerefRef(ref adj) => {
174 let (autoderefs, use_autoref) = match adj.autoref {
175 // Extracting a value from a box counts as a deref, but if we are
176 // just converting Box<[T, ..n]> to Box<[T]> we aren't really doing
177 // a deref (and wouldn't if we could treat Box like a normal struct).
178 Some(ty::AutoUnsizeUniq(..)) => (adj.autoderefs - 1, true),
179 // We are a bit paranoid about adjustments and thus might have a re-
180 // borrow here which merely derefs and then refs again (it might have
181 // a different region or mutability, but we don't care here. It might
182 // also be just in case we need to unsize. But if there are no nested
183 // adjustments then it should be a no-op).
184 Some(ty::AutoPtr(_, _, None)) if adj.autoderefs == 1 => {
186 // Don't skip a conversion from Box<T> to &T, etc.
188 let method_call = MethodCall::autoderef(expr.id, adj.autoderefs-1);
189 let method = bcx.tcx().method_map.borrow().get(&method_call).is_some();
191 // Don't skip an overloaded deref.
192 (adj.autoderefs, true)
194 (adj.autoderefs - 1, false)
197 _ => (adj.autoderefs, true),
200 _ => (adj.autoderefs, true)
205 let lval = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "auto_deref", expr.id));
206 datum = unpack_datum!(
207 bcx, deref_multiple(bcx, expr, lval.to_expr_datum(), autoderefs));
210 // (You might think there is a more elegant way to do this than a
211 // use_autoref bool, but then you remember that the borrow checker exists).
212 match (use_autoref, &adj.autoref) {
213 (true, &Some(ref a)) => {
214 datum = unpack_datum!(bcx, apply_autoref(a,
223 debug!("after adjustments, datum={}", datum.to_string(bcx.ccx()));
224 return DatumBlock::new(bcx, datum);
226 fn apply_autoref<'blk, 'tcx>(autoref: &ty::AutoRef<'tcx>,
227 bcx: Block<'blk, 'tcx>,
229 datum: Datum<'tcx, Expr>)
230 -> DatumBlock<'blk, 'tcx, Expr> {
232 let mut datum = datum;
234 let datum = match autoref {
235 &AutoPtr(_, _, ref a) | &AutoUnsafe(_, ref a) => {
238 &Some(box ref a) => {
239 datum = unpack_datum!(bcx, apply_autoref(a, bcx, expr, datum));
243 unpack_datum!(bcx, ref_ptr(bcx, expr, datum))
245 &ty::AutoUnsize(ref k) => {
246 debug!(" AutoUnsize");
247 unpack_datum!(bcx, unsize_expr(bcx, expr, datum, k))
250 &ty::AutoUnsizeUniq(ty::UnsizeLength(len)) => {
251 debug!(" AutoUnsizeUniq(UnsizeLength)");
252 unpack_datum!(bcx, unsize_unique_vec(bcx, expr, datum, len))
254 &ty::AutoUnsizeUniq(ref k) => {
255 debug!(" AutoUnsizeUniq");
256 unpack_datum!(bcx, unsize_unique_expr(bcx, expr, datum, k))
260 DatumBlock::new(bcx, datum)
263 fn ref_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
265 datum: Datum<'tcx, Expr>)
266 -> DatumBlock<'blk, 'tcx, Expr> {
267 debug!("ref_ptr(expr={}, datum={})",
268 expr.repr(bcx.tcx()),
269 datum.to_string(bcx.ccx()));
271 if !ty::type_is_sized(bcx.tcx(), datum.ty) {
272 debug!("Taking address of unsized type {}",
273 bcx.ty_to_string(datum.ty));
274 ref_fat_ptr(bcx, expr, datum)
276 debug!("Taking address of sized type {}",
277 bcx.ty_to_string(datum.ty));
278 auto_ref(bcx, datum, expr)
282 // Retrieve the information we are losing (making dynamic) in an unsizing
284 // When making a dtor, we need to do different things depending on the
285 // ownership of the object.. mk_ty is a function for turning `unadjusted_ty`
286 // into a type to be destructed. If we want to end up with a Box pointer,
287 // then mk_ty should make a Box pointer (T -> Box<T>), if we want a
288 // borrowed reference then it should be T -> &T.
289 fn unsized_info<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
290 kind: &ty::UnsizeKind<'tcx>,
292 unadjusted_ty: Ty<'tcx>,
293 mk_ty: |Ty<'tcx>| -> Ty<'tcx>) -> ValueRef {
294 debug!("unsized_info(kind={}, id={}, unadjusted_ty={})",
295 kind, id, unadjusted_ty.repr(bcx.tcx()));
297 &ty::UnsizeLength(len) => C_uint(bcx.ccx(), len),
298 &ty::UnsizeStruct(box ref k, tp_index) => match unadjusted_ty.sty {
299 ty::ty_struct(_, ref substs) => {
300 let ty_substs = substs.types.get_slice(subst::TypeSpace);
301 // The dtor for a field treats it like a value, so mk_ty
302 // should just be the identity function.
303 unsized_info(bcx, k, id, ty_substs[tp_index], |t| t)
305 _ => bcx.sess().bug(format!("UnsizeStruct with bad sty: {}",
306 bcx.ty_to_string(unadjusted_ty)).as_slice())
308 &ty::UnsizeVtable(ty::TyTrait { ref principal, .. }, _) => {
309 let substs = principal.substs.with_self_ty(unadjusted_ty).erase_regions();
311 Rc::new(ty::TraitRef { def_id: principal.def_id,
313 let trait_ref = trait_ref.subst(bcx.tcx(), bcx.fcx.param_substs);
314 let box_ty = mk_ty(unadjusted_ty);
316 meth::get_vtable(bcx, box_ty, trait_ref),
317 Type::vtable_ptr(bcx.ccx()))
322 fn unsize_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
324 datum: Datum<'tcx, Expr>,
325 k: &ty::UnsizeKind<'tcx>)
326 -> DatumBlock<'blk, 'tcx, Expr> {
328 let datum_ty = datum.ty;
329 let unsized_ty = ty::unsize_ty(tcx, datum_ty, k, expr.span);
330 debug!("unsized_ty={}", unsized_ty.repr(bcx.tcx()));
331 let dest_ty = ty::mk_open(tcx, unsized_ty);
332 debug!("dest_ty={}", unsized_ty.repr(bcx.tcx()));
333 // Closures for extracting and manipulating the data and payload parts of
336 &ty::UnsizeStruct(..) =>
337 |bcx, val| PointerCast(bcx,
339 type_of::type_of(bcx.ccx(), unsized_ty).ptr_to()),
340 &ty::UnsizeLength(..) =>
341 |bcx, val| GEPi(bcx, val, &[0u, 0u]),
342 &ty::UnsizeVtable(..) =>
343 |_bcx, val| PointerCast(bcx, val, Type::i8p(bcx.ccx()))
345 let info = |bcx, _val| unsized_info(bcx,
353 mutbl: ast::MutImmutable
355 into_fat_ptr(bcx, expr, datum, dest_ty, base, info)
358 fn ref_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
360 datum: Datum<'tcx, Expr>)
361 -> DatumBlock<'blk, 'tcx, Expr> {
363 let dest_ty = ty::close_type(tcx, datum.ty);
364 let base = |bcx, val| Load(bcx, get_dataptr(bcx, val));
365 let len = |bcx, val| Load(bcx, get_len(bcx, val));
366 into_fat_ptr(bcx, expr, datum, dest_ty, base, len)
369 fn into_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
371 datum: Datum<'tcx, Expr>,
373 base: |Block<'blk, 'tcx>, ValueRef| -> ValueRef,
374 info: |Block<'blk, 'tcx>, ValueRef| -> ValueRef)
375 -> DatumBlock<'blk, 'tcx, Expr> {
379 let lval = unpack_datum!(bcx,
380 datum.to_lvalue_datum(bcx, "into_fat_ptr", expr.id));
381 let base = base(bcx, lval.val);
382 let info = info(bcx, lval.val);
384 let scratch = rvalue_scratch_datum(bcx, dest_ty, "__fat_ptr");
385 Store(bcx, base, get_dataptr(bcx, scratch.val));
386 Store(bcx, info, get_len(bcx, scratch.val));
388 DatumBlock::new(bcx, scratch.to_expr_datum())
391 fn unsize_unique_vec<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
393 datum: Datum<'tcx, Expr>,
395 -> DatumBlock<'blk, 'tcx, Expr> {
399 let datum_ty = datum.ty;
401 let lval = unpack_datum!(bcx,
402 datum.to_lvalue_datum(bcx, "unsize_unique_vec", expr.id));
404 let ll_len = C_uint(bcx.ccx(), len);
405 let unit_ty = ty::sequence_element_type(tcx, ty::type_content(datum_ty));
406 let vec_ty = ty::mk_uniq(tcx, ty::mk_vec(tcx, unit_ty, None));
407 let scratch = rvalue_scratch_datum(bcx, vec_ty, "__unsize_unique");
409 let base = get_dataptr(bcx, scratch.val);
410 let base = PointerCast(bcx,
412 type_of::type_of(bcx.ccx(), datum_ty).ptr_to());
413 bcx = lval.store_to(bcx, base);
415 Store(bcx, ll_len, get_len(bcx, scratch.val));
416 DatumBlock::new(bcx, scratch.to_expr_datum())
419 fn unsize_unique_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
421 datum: Datum<'tcx, Expr>,
422 k: &ty::UnsizeKind<'tcx>)
423 -> DatumBlock<'blk, 'tcx, Expr> {
427 let datum_ty = datum.ty;
428 let unboxed_ty = match datum_ty.sty {
430 _ => bcx.sess().bug(format!("Expected ty_uniq, found {}",
431 bcx.ty_to_string(datum_ty)).as_slice())
433 let result_ty = ty::mk_uniq(tcx, ty::unsize_ty(tcx, unboxed_ty, k, expr.span));
435 let lval = unpack_datum!(bcx,
436 datum.to_lvalue_datum(bcx, "unsize_unique_expr", expr.id));
438 let scratch = rvalue_scratch_datum(bcx, result_ty, "__uniq_fat_ptr");
439 let llbox_ty = type_of::type_of(bcx.ccx(), datum_ty);
440 let base = PointerCast(bcx, get_dataptr(bcx, scratch.val), llbox_ty.ptr_to());
441 bcx = lval.store_to(bcx, base);
443 let info = unsized_info(bcx, k, expr.id, unboxed_ty, |t| ty::mk_uniq(tcx, t));
444 Store(bcx, info, get_len(bcx, scratch.val));
446 let scratch = unpack_datum!(bcx,
447 scratch.to_expr_datum().to_lvalue_datum(bcx,
448 "fresh_uniq_fat_ptr",
451 DatumBlock::new(bcx, scratch.to_expr_datum())
454 fn add_env<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
456 datum: Datum<'tcx, Expr>)
457 -> DatumBlock<'blk, 'tcx, Expr> {
458 // This is not the most efficient thing possible; since closures
459 // are two words it'd be better if this were compiled in
460 // 'dest' mode, but I can't find a nice way to structure the
461 // code and keep it DRY that accommodates that use case at the
464 let closure_ty = expr_ty_adjusted(bcx, expr);
465 let fn_ptr = datum.to_llscalarish(bcx);
466 let def = ty::resolve_expr(bcx.tcx(), expr);
467 closure::make_closure_from_bare_fn(bcx, closure_ty, def, fn_ptr)
471 /// Translates an expression in "lvalue" mode -- meaning that it returns a reference to the memory
472 /// that the expr represents.
474 /// If this expression is an rvalue, this implies introducing a temporary. In other words,
475 /// something like `x().f` is translated into roughly the equivalent of
477 /// { tmp = x(); tmp.f }
478 pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
481 -> DatumBlock<'blk, 'tcx, Lvalue> {
483 let datum = unpack_datum!(bcx, trans(bcx, expr));
484 return datum.to_lvalue_datum(bcx, name, expr.id);
487 /// A version of `trans` that ignores adjustments. You almost certainly do not want to call this
489 fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
491 -> DatumBlock<'blk, 'tcx, Expr> {
494 debug!("trans_unadjusted(expr={})", bcx.expr_to_string(expr));
495 let _indenter = indenter();
497 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
499 return match ty::expr_kind(bcx.tcx(), expr) {
500 ty::LvalueExpr | ty::RvalueDatumExpr => {
501 let datum = unpack_datum!(bcx, {
502 trans_datum_unadjusted(bcx, expr)
505 DatumBlock {bcx: bcx, datum: datum}
508 ty::RvalueStmtExpr => {
509 bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
510 nil(bcx, expr_ty(bcx, expr))
513 ty::RvalueDpsExpr => {
514 let ty = expr_ty(bcx, expr);
515 if type_is_zero_size(bcx.ccx(), ty) {
516 bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
519 let scratch = rvalue_scratch_datum(bcx, ty, "");
520 bcx = trans_rvalue_dps_unadjusted(
521 bcx, expr, SaveIn(scratch.val));
523 // Note: this is not obviously a good idea. It causes
524 // immediate values to be loaded immediately after a
525 // return from a call or other similar expression,
526 // which in turn leads to alloca's having shorter
527 // lifetimes and hence larger stack frames. However,
528 // in turn it can lead to more register pressure.
529 // Still, in practice it seems to increase
530 // performance, since we have fewer problems with
532 let scratch = unpack_datum!(
533 bcx, scratch.to_appropriate_datum(bcx));
535 DatumBlock::new(bcx, scratch.to_expr_datum())
540 fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: Ty<'tcx>)
541 -> DatumBlock<'blk, 'tcx, Expr> {
542 let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
543 let datum = immediate_rvalue(llval, ty);
544 DatumBlock::new(bcx, datum.to_expr_datum())
548 fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
550 -> DatumBlock<'blk, 'tcx, Expr> {
553 let _icx = push_ctxt("trans_datum_unadjusted");
556 ast::ExprParen(ref e) => {
559 ast::ExprPath(_) => {
560 trans_def(bcx, expr, bcx.def(expr.id))
562 ast::ExprField(ref base, ident) => {
563 trans_rec_field(bcx, &**base, ident.node)
565 ast::ExprTupField(ref base, idx) => {
566 trans_rec_tup_field(bcx, &**base, idx.node)
568 ast::ExprIndex(ref base, ref idx) => {
569 trans_index(bcx, expr, &**base, &**idx, MethodCall::expr(expr.id))
571 ast::ExprSlice(ref base, ref start, ref end, _) => {
572 let _icx = push_ctxt("trans_slice");
575 let method_call = MethodCall::expr(expr.id);
576 let method_ty = ccx.tcx()
580 .map(|method| method.ty);
581 let base_datum = unpack_datum!(bcx, trans(bcx, &**base));
583 let mut args = vec![];
584 start.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
585 end.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
587 let result_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty.unwrap())).unwrap();
588 let scratch = rvalue_scratch_datum(bcx, result_ty, "trans_slice");
591 trans_overloaded_op(bcx,
596 Some(SaveIn(scratch.val))));
597 DatumBlock::new(bcx, scratch.to_expr_datum())
599 ast::ExprBox(_, ref contents) => {
600 // Special case for `Box<T>`
601 let box_ty = expr_ty(bcx, expr);
602 let contents_ty = expr_ty(bcx, &**contents);
605 trans_uniq_expr(bcx, box_ty, &**contents, contents_ty)
607 _ => bcx.sess().span_bug(expr.span,
608 "expected unique box")
612 ast::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &**lit),
613 ast::ExprBinary(op, ref lhs, ref rhs) => {
614 trans_binary(bcx, expr, op, &**lhs, &**rhs)
616 ast::ExprUnary(op, ref x) => {
617 trans_unary(bcx, expr, op, &**x)
619 ast::ExprAddrOf(_, ref x) => {
621 ast::ExprRepeat(..) | ast::ExprVec(..) => {
622 // Special case for slices.
623 let cleanup_debug_loc =
624 debuginfo::get_cleanup_debug_loc_for_ast_node(x.id, x.span, false);
625 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
626 let datum = unpack_datum!(
627 bcx, tvec::trans_slice_vec(bcx, expr, &**x));
628 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
629 DatumBlock::new(bcx, datum)
632 trans_addr_of(bcx, expr, &**x)
636 ast::ExprCast(ref val, _) => {
637 // Datum output mode means this is a scalar cast:
638 trans_imm_cast(bcx, &**val, expr.id)
641 bcx.tcx().sess.span_bug(
643 format!("trans_rvalue_datum_unadjusted reached \
644 fall-through case: {}",
645 expr.node).as_slice());
650 fn trans_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
652 get_idx: |&'blk ty::ctxt<'tcx>, &[ty::field<'tcx>]| -> uint)
653 -> DatumBlock<'blk, 'tcx, Expr> {
655 let _icx = push_ctxt("trans_rec_field");
657 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
658 let bare_ty = ty::unopen_type(base_datum.ty);
659 let repr = adt::represent_type(bcx.ccx(), bare_ty);
660 with_field_tys(bcx.tcx(), bare_ty, None, |discr, field_tys| {
661 let ix = get_idx(bcx.tcx(), field_tys);
662 let d = base_datum.get_element(
665 |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, ix));
667 if ty::type_is_sized(bcx.tcx(), d.ty) {
668 DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
670 let scratch = rvalue_scratch_datum(bcx, ty::mk_open(bcx.tcx(), d.ty), "");
671 Store(bcx, d.val, get_dataptr(bcx, scratch.val));
672 let info = Load(bcx, get_len(bcx, base_datum.val));
673 Store(bcx, info, get_len(bcx, scratch.val));
675 DatumBlock::new(bcx, scratch.to_expr_datum())
682 /// Translates `base.field`.
683 fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
686 -> DatumBlock<'blk, 'tcx, Expr> {
687 trans_field(bcx, base, |tcx, field_tys| ty::field_idx_strict(tcx, field.name, field_tys))
690 /// Translates `base.<idx>`.
691 fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
694 -> DatumBlock<'blk, 'tcx, Expr> {
695 trans_field(bcx, base, |_, _| idx)
698 fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
699 index_expr: &ast::Expr,
702 method_call: MethodCall)
703 -> DatumBlock<'blk, 'tcx, Expr> {
704 //! Translates `base[idx]`.
706 let _icx = push_ctxt("trans_index");
710 // Check for overloaded index.
711 let method_ty = ccx.tcx()
715 .map(|method| method.ty);
716 let elt_datum = match method_ty {
718 let base_datum = unpack_datum!(bcx, trans(bcx, base));
720 // Translate index expression.
721 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
723 let ref_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty)).unwrap();
724 let elt_ty = match ty::deref(ref_ty, true) {
726 bcx.tcx().sess.span_bug(index_expr.span,
727 "index method didn't return a \
728 dereferenceable type?!")
730 Some(elt_tm) => elt_tm.ty,
733 // Overloaded. Evaluate `trans_overloaded_op`, which will
734 // invoke the user's index() method, which basically yields
735 // a `&T` pointer. We can then proceed down the normal
736 // path (below) to dereference that `&T`.
737 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_index_elt");
739 trans_overloaded_op(bcx,
743 vec![(ix_datum, idx.id)],
744 Some(SaveIn(scratch.val))));
745 let datum = scratch.to_expr_datum();
746 if ty::type_is_sized(bcx.tcx(), elt_ty) {
747 Datum::new(datum.to_llscalarish(bcx), elt_ty, LvalueExpr)
749 Datum::new(datum.val, ty::mk_open(bcx.tcx(), elt_ty), LvalueExpr)
753 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
757 // Translate index expression and cast to a suitable LLVM integer.
758 // Rust is less strict than LLVM in this regard.
759 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
760 let ix_val = ix_datum.to_llscalarish(bcx);
761 let ix_size = machine::llbitsize_of_real(bcx.ccx(),
763 let int_size = machine::llbitsize_of_real(bcx.ccx(),
766 if ix_size < int_size {
767 if ty::type_is_signed(expr_ty(bcx, idx)) {
768 SExt(bcx, ix_val, ccx.int_type())
769 } else { ZExt(bcx, ix_val, ccx.int_type()) }
770 } else if ix_size > int_size {
771 Trunc(bcx, ix_val, ccx.int_type())
779 ty::sequence_element_type(bcx.tcx(),
781 base::maybe_name_value(bcx.ccx(), vt.llunit_size, "unit_sz");
783 let (base, len) = base_datum.get_vec_base_and_len(bcx);
785 debug!("trans_index: base {}", bcx.val_to_string(base));
786 debug!("trans_index: len {}", bcx.val_to_string(len));
788 let bounds_check = ICmp(bcx, llvm::IntUGE, ix_val, len);
789 let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
790 let expected = Call(bcx,
792 &[bounds_check, C_bool(ccx, false)],
794 bcx = with_cond(bcx, expected, |bcx| {
795 controlflow::trans_fail_bounds_check(bcx,
800 let elt = InBoundsGEP(bcx, base, &[ix_val]);
801 let elt = PointerCast(bcx, elt, vt.llunit_ty.ptr_to());
802 Datum::new(elt, vt.unit_ty, LvalueExpr)
806 DatumBlock::new(bcx, elt_datum)
809 fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
810 ref_expr: &ast::Expr,
812 -> DatumBlock<'blk, 'tcx, Expr> {
813 //! Translates a reference to a path.
815 let _icx = push_ctxt("trans_def_lvalue");
817 def::DefFn(..) | def::DefStaticMethod(..) | def::DefMethod(..) |
818 def::DefStruct(_) | def::DefVariant(..) => {
819 trans_def_fn_unadjusted(bcx, ref_expr, def)
821 def::DefStatic(did, _) => {
822 // There are two things that may happen here:
823 // 1) If the static item is defined in this crate, it will be
824 // translated using `get_item_val`, and we return a pointer to
826 // 2) If the static item is defined in another crate then we add
827 // (or reuse) a declaration of an external global, and return a
829 let const_ty = expr_ty(bcx, ref_expr);
831 fn get_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, did: ast::DefId,
832 const_ty: Ty<'tcx>) -> ValueRef {
833 // For external constants, we don't inline.
834 if did.krate == ast::LOCAL_CRATE {
837 // The LLVM global has the type of its initializer,
838 // which may not be equal to the enum's type for
840 let val = base::get_item_val(bcx.ccx(), did.node);
841 let pty = type_of::type_of(bcx.ccx(), const_ty).ptr_to();
842 PointerCast(bcx, val, pty)
845 base::get_extern_const(bcx.ccx(), did, const_ty)
848 let val = get_val(bcx, did, const_ty);
849 DatumBlock::new(bcx, Datum::new(val, const_ty, LvalueExpr))
851 def::DefConst(did) => {
852 // First, inline any external constants into the local crate so we
853 // can be sure to get the LLVM value corresponding to it.
854 let did = inline::maybe_instantiate_inline(bcx.ccx(), did);
855 if did.krate != ast::LOCAL_CRATE {
856 bcx.tcx().sess.span_bug(ref_expr.span,
857 "cross crate constant could not \
860 let val = base::get_item_val(bcx.ccx(), did.node);
862 // Next, we need to crate a ByRef rvalue datum to return. We can't
863 // use the normal .to_ref_datum() function because the type of
864 // `val` is not actually the same as `const_ty`.
866 // To get around this, we make a custom alloca slot with the
867 // appropriate type (const_ty), and then we cast it to a pointer of
868 // typeof(val), store the value, and then hand this slot over to
869 // the datum infrastructure.
870 let const_ty = expr_ty(bcx, ref_expr);
871 let llty = type_of::type_of(bcx.ccx(), const_ty);
872 let slot = alloca(bcx, llty, "const");
873 let pty = Type::from_ref(unsafe { llvm::LLVMTypeOf(val) }).ptr_to();
874 Store(bcx, val, PointerCast(bcx, slot, pty));
876 let datum = Datum::new(slot, const_ty, Rvalue::new(ByRef));
877 DatumBlock::new(bcx, datum.to_expr_datum())
880 DatumBlock::new(bcx, trans_local_var(bcx, def).to_expr_datum())
885 fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
887 -> Block<'blk, 'tcx> {
889 let _icx = push_ctxt("trans_rvalue_stmt");
891 if bcx.unreachable.get() {
895 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
898 ast::ExprParen(ref e) => {
899 trans_into(bcx, &**e, Ignore)
901 ast::ExprBreak(label_opt) => {
902 controlflow::trans_break(bcx, expr.id, label_opt)
904 ast::ExprAgain(label_opt) => {
905 controlflow::trans_cont(bcx, expr.id, label_opt)
907 ast::ExprRet(ref ex) => {
908 controlflow::trans_ret(bcx, ex.as_ref().map(|e| &**e))
910 ast::ExprWhile(ref cond, ref body, _) => {
911 controlflow::trans_while(bcx, expr.id, &**cond, &**body)
913 ast::ExprForLoop(ref pat, ref head, ref body, _) => {
914 controlflow::trans_for(bcx,
920 ast::ExprLoop(ref body, _) => {
921 controlflow::trans_loop(bcx, expr.id, &**body)
923 ast::ExprAssign(ref dst, ref src) => {
924 let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
925 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &**dst, "assign"));
927 if ty::type_needs_drop(bcx.tcx(), dst_datum.ty) {
928 // If there are destructors involved, make sure we
929 // are copying from an rvalue, since that cannot possible
930 // alias an lvalue. We are concerned about code like:
938 // where e.g. a : Option<Foo> and a.b :
939 // Option<Foo>. In that case, freeing `a` before the
940 // assignment may also free `a.b`!
942 // We could avoid this intermediary with some analysis
943 // to determine whether `dst` may possibly own `src`.
944 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
945 let src_datum = unpack_datum!(
946 bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
947 bcx = glue::drop_ty(bcx,
950 Some(NodeInfo { id: expr.id, span: expr.span }));
951 src_datum.store_to(bcx, dst_datum.val)
953 src_datum.store_to(bcx, dst_datum.val)
956 ast::ExprAssignOp(op, ref dst, ref src) => {
957 trans_assign_op(bcx, expr, op, &**dst, &**src)
959 ast::ExprInlineAsm(ref a) => {
960 asm::trans_inline_asm(bcx, a)
963 bcx.tcx().sess.span_bug(
965 format!("trans_rvalue_stmt_unadjusted reached \
966 fall-through case: {}",
967 expr.node).as_slice());
972 fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
975 -> Block<'blk, 'tcx> {
976 let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
980 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
983 ast::ExprParen(ref e) => {
984 trans_into(bcx, &**e, dest)
986 ast::ExprPath(_) => {
987 trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
989 ast::ExprIf(ref cond, ref thn, ref els) => {
990 controlflow::trans_if(bcx, expr.id, &**cond, &**thn, els.as_ref().map(|e| &**e), dest)
992 ast::ExprMatch(ref discr, ref arms, _) => {
993 _match::trans_match(bcx, expr, &**discr, arms.as_slice(), dest)
995 ast::ExprBlock(ref blk) => {
996 controlflow::trans_block(bcx, &**blk, dest)
998 ast::ExprStruct(_, ref fields, ref base) => {
1001 base.as_ref().map(|e| &**e),
1006 ast::ExprTup(ref args) => {
1007 let numbered_fields: Vec<(uint, &ast::Expr)> =
1008 args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
1012 numbered_fields.as_slice(),
1015 Some(NodeInfo { id: expr.id, span: expr.span }))
1017 ast::ExprLit(ref lit) => {
1019 ast::LitStr(ref s, _) => {
1020 tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
1025 .span_bug(expr.span,
1026 "trans_rvalue_dps_unadjusted shouldn't be \
1027 translating this type of literal")
1031 ast::ExprVec(..) | ast::ExprRepeat(..) => {
1032 tvec::trans_fixed_vstore(bcx, expr, dest)
1034 ast::ExprClosure(_, _, ref decl, ref body) |
1035 ast::ExprProc(ref decl, ref body) => {
1036 // Check the side-table to see whether this is an unboxed
1037 // closure or an older, legacy style closure. Store this
1038 // into a variable to ensure the the RefCell-lock is
1039 // released before we recurse.
1040 let is_unboxed_closure =
1041 bcx.tcx().unboxed_closures.borrow().contains_key(&ast_util::local_def(expr.id));
1042 if is_unboxed_closure {
1043 closure::trans_unboxed_closure(bcx, &**decl, &**body, expr.id, dest)
1045 let expr_ty = expr_ty(bcx, expr);
1046 let store = ty::ty_closure_store(expr_ty);
1047 debug!("translating block function {} with type {}",
1048 expr_to_string(expr), expr_ty.repr(tcx));
1049 closure::trans_expr_fn(bcx, store, &**decl, &**body, expr.id, dest)
1052 ast::ExprCall(ref f, ref args) => {
1053 if bcx.tcx().is_method_call(expr.id) {
1054 trans_overloaded_call(bcx,
1060 callee::trans_call(bcx,
1063 callee::ArgExprs(args.as_slice()),
1067 ast::ExprMethodCall(_, _, ref args) => {
1068 callee::trans_method_call(bcx,
1071 callee::ArgExprs(args.as_slice()),
1074 ast::ExprBinary(_, ref lhs, ref rhs) => {
1075 // if not overloaded, would be RvalueDatumExpr
1076 let lhs = unpack_datum!(bcx, trans(bcx, &**lhs));
1077 let rhs_datum = unpack_datum!(bcx, trans(bcx, &**rhs));
1078 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), lhs,
1079 vec![(rhs_datum, rhs.id)], Some(dest)).bcx
1081 ast::ExprUnary(_, ref subexpr) => {
1082 // if not overloaded, would be RvalueDatumExpr
1083 let arg = unpack_datum!(bcx, trans(bcx, &**subexpr));
1084 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id),
1085 arg, Vec::new(), Some(dest)).bcx
1087 ast::ExprIndex(ref base, ref idx) => {
1088 // if not overloaded, would be RvalueDatumExpr
1089 let base = unpack_datum!(bcx, trans(bcx, &**base));
1090 let idx_datum = unpack_datum!(bcx, trans(bcx, &**idx));
1091 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), base,
1092 vec![(idx_datum, idx.id)], Some(dest)).bcx
1094 ast::ExprCast(ref val, _) => {
1095 // DPS output mode means this is a trait cast:
1096 if ty::type_is_trait(node_id_type(bcx, expr.id)) {
1098 bcx.tcx().object_cast_map.borrow()
1100 .map(|t| (*t).clone())
1102 let trait_ref = trait_ref.subst(bcx.tcx(), bcx.fcx.param_substs);
1103 let datum = unpack_datum!(bcx, trans(bcx, &**val));
1104 meth::trans_trait_cast(bcx, datum, expr.id,
1107 bcx.tcx().sess.span_bug(expr.span,
1108 "expr_cast of non-trait");
1111 ast::ExprAssignOp(op, ref dst, ref src) => {
1112 trans_assign_op(bcx, expr, op, &**dst, &**src)
1115 bcx.tcx().sess.span_bug(
1117 format!("trans_rvalue_dps_unadjusted reached fall-through \
1119 expr.node).as_slice());
1124 fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1125 ref_expr: &ast::Expr,
1128 -> Block<'blk, 'tcx> {
1129 let _icx = push_ctxt("trans_def_dps_unadjusted");
1131 let lldest = match dest {
1132 SaveIn(lldest) => lldest,
1133 Ignore => { return bcx; }
1137 def::DefVariant(tid, vid, _) => {
1138 let variant_info = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
1139 if variant_info.args.len() > 0u {
1141 let llfn = callee::trans_fn_ref(bcx, vid, ExprId(ref_expr.id));
1142 Store(bcx, llfn, lldest);
1146 let ty = expr_ty(bcx, ref_expr);
1147 let repr = adt::represent_type(bcx.ccx(), ty);
1148 adt::trans_set_discr(bcx, &*repr, lldest,
1149 variant_info.disr_val);
1153 def::DefStruct(_) => {
1154 let ty = expr_ty(bcx, ref_expr);
1156 ty::ty_struct(did, _) if ty::has_dtor(bcx.tcx(), did) => {
1157 let repr = adt::represent_type(bcx.ccx(), ty);
1158 adt::trans_set_discr(bcx, &*repr, lldest, 0);
1165 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1166 "Non-DPS def {} referened by {}",
1167 def, bcx.node_id_to_string(ref_expr.id)).as_slice());
1172 fn trans_def_fn_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1173 ref_expr: &ast::Expr,
1175 -> DatumBlock<'blk, 'tcx, Expr> {
1176 let _icx = push_ctxt("trans_def_datum_unadjusted");
1178 let llfn = match def {
1179 def::DefFn(did, _) |
1180 def::DefStruct(did) | def::DefVariant(_, did, _) |
1181 def::DefStaticMethod(did, def::FromImpl(_)) |
1182 def::DefMethod(did, _, def::FromImpl(_)) => {
1183 callee::trans_fn_ref(bcx, did, ExprId(ref_expr.id))
1185 def::DefStaticMethod(impl_did, def::FromTrait(trait_did)) |
1186 def::DefMethod(impl_did, _, def::FromTrait(trait_did)) => {
1187 meth::trans_static_method_callee(bcx, impl_did,
1188 trait_did, ref_expr.id)
1191 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1192 "trans_def_fn_unadjusted invoked on: {} for {}",
1194 ref_expr.repr(bcx.tcx())).as_slice());
1198 let fn_ty = expr_ty(bcx, ref_expr);
1199 DatumBlock::new(bcx, Datum::new(llfn, fn_ty, RvalueExpr(Rvalue::new(ByValue))))
1202 /// Translates a reference to a local variable or argument. This always results in an lvalue datum.
1203 pub fn trans_local_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1205 -> Datum<'tcx, Lvalue> {
1206 let _icx = push_ctxt("trans_local_var");
1209 def::DefUpvar(nid, _, _) => {
1210 // Can't move upvars, so this is never a ZeroMemLastUse.
1211 let local_ty = node_id_type(bcx, nid);
1212 match bcx.fcx.llupvars.borrow().get(&nid) {
1213 Some(&val) => Datum::new(val, local_ty, Lvalue),
1215 bcx.sess().bug(format!(
1216 "trans_local_var: no llval for upvar {} found",
1221 def::DefLocal(nid) => {
1222 let datum = match bcx.fcx.lllocals.borrow().get(&nid) {
1225 bcx.sess().bug(format!(
1226 "trans_local_var: no datum for local/arg {} found",
1230 debug!("take_local(nid={}, v={}, ty={})",
1231 nid, bcx.val_to_string(datum.val), bcx.ty_to_string(datum.ty));
1235 bcx.sess().unimpl(format!(
1236 "unsupported def type in trans_local_var: {}",
1242 /// Helper for enumerating the field types of structs, enums, or records. The optional node ID here
1243 /// is the node ID of the path identifying the enum variant in use. If none, this cannot possibly
1244 /// an enum variant (so, if it is and `node_id_opt` is none, this function panics).
1245 pub fn with_field_tys<'tcx, R>(tcx: &ty::ctxt<'tcx>,
1247 node_id_opt: Option<ast::NodeId>,
1248 op: |ty::Disr, (&[ty::field<'tcx>])| -> R)
1251 ty::ty_struct(did, ref substs) => {
1252 op(0, struct_fields(tcx, did, substs).as_slice())
1255 ty::ty_tup(ref v) => {
1256 op(0, tup_fields(v.as_slice()).as_slice())
1259 ty::ty_enum(_, ref substs) => {
1260 // We want the *variant* ID here, not the enum ID.
1263 tcx.sess.bug(format!(
1264 "cannot get field types from the enum type {} \
1266 ty.repr(tcx)).as_slice());
1269 let def = tcx.def_map.borrow()[node_id].clone();
1271 def::DefVariant(enum_id, variant_id, _) => {
1272 let variant_info = ty::enum_variant_with_id(
1273 tcx, enum_id, variant_id);
1274 op(variant_info.disr_val,
1280 tcx.sess.bug("resolve didn't map this expr to a \
1289 tcx.sess.bug(format!(
1290 "cannot get field types from the type {}",
1291 ty.repr(tcx)).as_slice());
1296 fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1297 fields: &[ast::Field],
1298 base: Option<&ast::Expr>,
1299 expr_span: codemap::Span,
1300 expr_id: ast::NodeId,
1301 dest: Dest) -> Block<'blk, 'tcx> {
1302 let _icx = push_ctxt("trans_rec");
1304 let ty = node_id_type(bcx, expr_id);
1305 let tcx = bcx.tcx();
1306 with_field_tys(tcx, ty, Some(expr_id), |discr, field_tys| {
1307 let mut need_base = Vec::from_elem(field_tys.len(), true);
1309 let numbered_fields = fields.iter().map(|field| {
1311 field_tys.iter().position(|field_ty|
1312 field_ty.name == field.ident.node.name);
1315 need_base[i] = false;
1319 tcx.sess.span_bug(field.span,
1320 "Couldn't find field in struct type")
1323 }).collect::<Vec<_>>();
1324 let optbase = match base {
1325 Some(base_expr) => {
1326 let mut leftovers = Vec::new();
1327 for (i, b) in need_base.iter().enumerate() {
1329 leftovers.push((i, field_tys[i].mt.ty))
1332 Some(StructBaseInfo {expr: base_expr,
1333 fields: leftovers })
1336 if need_base.iter().any(|b| *b) {
1337 tcx.sess.span_bug(expr_span, "missing fields and no base expr")
1346 numbered_fields.as_slice(),
1349 Some(NodeInfo { id: expr_id, span: expr_span }))
1354 * Information that `trans_adt` needs in order to fill in the fields
1355 * of a struct copied from a base struct (e.g., from an expression
1356 * like `Foo { a: b, ..base }`.
1358 * Note that `fields` may be empty; the base expression must always be
1359 * evaluated for side-effects.
1361 pub struct StructBaseInfo<'a, 'tcx> {
1362 /// The base expression; will be evaluated after all explicit fields.
1363 expr: &'a ast::Expr,
1364 /// The indices of fields to copy paired with their types.
1365 fields: Vec<(uint, Ty<'tcx>)>
1369 * Constructs an ADT instance:
1371 * - `fields` should be a list of field indices paired with the
1372 * expression to store into that field. The initializers will be
1373 * evaluated in the order specified by `fields`.
1375 * - `optbase` contains information on the base struct (if any) from
1376 * which remaining fields are copied; see comments on `StructBaseInfo`.
1378 pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1381 fields: &[(uint, &ast::Expr)],
1382 optbase: Option<StructBaseInfo<'a, 'tcx>>,
1384 source_location: Option<NodeInfo>)
1385 -> Block<'blk, 'tcx> {
1386 let _icx = push_ctxt("trans_adt");
1388 let repr = adt::represent_type(bcx.ccx(), ty);
1390 match source_location {
1391 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1397 // If we don't care about the result, just make a
1398 // temporary stack slot
1399 let addr = match dest {
1401 Ignore => alloc_ty(bcx, ty, "temp"),
1404 // This scope holds intermediates that must be cleaned should
1405 // panic occur before the ADT as a whole is ready.
1406 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1408 // First we trans the base, if we have one, to the dest
1409 for base in optbase.iter() {
1410 assert_eq!(discr, 0);
1412 match ty::expr_kind(bcx.tcx(), &*base.expr) {
1413 ty::RvalueDpsExpr | ty::RvalueDatumExpr if !ty::type_needs_drop(bcx.tcx(), ty) => {
1414 bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
1416 ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr"),
1418 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
1419 for &(i, t) in base.fields.iter() {
1420 let datum = base_datum.get_element(
1421 bcx, t, |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, i));
1422 assert!(ty::type_is_sized(bcx.tcx(), datum.ty));
1423 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1424 bcx = datum.store_to(bcx, dest);
1430 match source_location {
1431 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1437 if ty::type_is_simd(bcx.tcx(), ty) {
1438 // This is the constructor of a SIMD type, such types are
1439 // always primitive machine types and so do not have a
1440 // destructor or require any clean-up.
1441 let llty = type_of::type_of(bcx.ccx(), ty);
1443 // keep a vector as a register, and running through the field
1444 // `insertelement`ing them directly into that register
1445 // (i.e. avoid GEPi and `store`s to an alloca) .
1446 let mut vec_val = C_undef(llty);
1448 for &(i, ref e) in fields.iter() {
1449 let block_datum = trans(bcx, &**e);
1450 bcx = block_datum.bcx;
1451 let position = C_uint(bcx.ccx(), i);
1452 let value = block_datum.datum.to_llscalarish(bcx);
1453 vec_val = InsertElement(bcx, vec_val, value, position);
1455 Store(bcx, vec_val, addr);
1457 // Now, we just overwrite the fields we've explicitly specified
1458 for &(i, ref e) in fields.iter() {
1459 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1460 let e_ty = expr_ty_adjusted(bcx, &**e);
1461 bcx = trans_into(bcx, &**e, SaveIn(dest));
1462 let scope = cleanup::CustomScope(custom_cleanup_scope);
1463 fcx.schedule_lifetime_end(scope, dest);
1464 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,
1546 contents_ty: Ty<'tcx>)
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 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,
1785 lhs: Datum<'tcx, Expr>,
1786 rhs: Vec<(Datum<'tcx, 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>(tcx: &ty::ctxt<'tcx>, t: Ty<'tcx>) -> cast_kind {
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<'tcx>(t_in: Ty<'tcx>, t_out: Ty<'tcx>) -> 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>,
2033 datum: Datum<'tcx, Expr>,
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>,
2058 datum: Datum<'tcx, Expr>,
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>,
2072 datum: Datum<'tcx, Expr>,
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 .get(&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 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 /// We microoptimize derefs of owned pointers a bit here. Basically, the idea is to make the
2166 /// deref of an rvalue result in an rvalue. This helps to avoid intermediate stack slots in the
2167 /// resulting LLVM. The idea here is that, if the `Box<T>` pointer is an rvalue, then we can
2168 /// schedule a *shallow* free of the `Box<T>` pointer, and then return a ByRef rvalue into the
2169 /// pointer. Because the free is shallow, it is legit to return an rvalue, because we know that
2170 /// the contents are not yet scheduled to be freed. The language rules ensure that the contents
2171 /// will be used (or moved) before the free occurs.
2172 fn deref_owned_pointer<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2174 datum: Datum<'tcx, Expr>,
2175 content_ty: Ty<'tcx>)
2176 -> DatumBlock<'blk, 'tcx, Expr> {
2178 RvalueExpr(Rvalue { mode: ByRef }) => {
2179 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2180 let ptr = Load(bcx, datum.val);
2181 if !type_is_zero_size(bcx.ccx(), content_ty) {
2182 bcx.fcx.schedule_free_value(scope, ptr, cleanup::HeapExchange, content_ty);
2185 RvalueExpr(Rvalue { mode: ByValue }) => {
2186 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2187 if !type_is_zero_size(bcx.ccx(), content_ty) {
2188 bcx.fcx.schedule_free_value(scope, datum.val, cleanup::HeapExchange,
2195 // If we had an rvalue in, we produce an rvalue out.
2196 let (llptr, kind) = match datum.kind {
2198 (Load(bcx, datum.val), LvalueExpr)
2200 RvalueExpr(Rvalue { mode: ByRef }) => {
2201 (Load(bcx, datum.val), RvalueExpr(Rvalue::new(ByRef)))
2203 RvalueExpr(Rvalue { mode: ByValue }) => {
2204 (datum.val, RvalueExpr(Rvalue::new(ByRef)))
2208 let datum = Datum { ty: content_ty, val: llptr, kind: kind };
2209 DatumBlock { bcx: bcx, datum: datum }