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};
46 use trans::cleanup::{mod, CleanupMethods};
56 use middle::ty::{struct_fields, tup_fields};
57 use middle::ty::{AdjustDerefRef, AdjustAddEnv, AutoUnsafe};
58 use middle::ty::{AutoPtr};
59 use middle::ty::{mod, Ty};
60 use middle::ty::MethodCall;
61 use util::common::indenter;
62 use util::ppaux::Repr;
63 use trans::machine::{llsize_of, llsize_of_alloc};
64 use trans::type_::Type;
66 use syntax::{ast, ast_util, codemap};
67 use syntax::print::pprust::{expr_to_string};
73 // These are passed around by the code generating functions to track the
74 // destination of a computation's value.
76 #[deriving(PartialEq)]
85 pub fn to_string(&self, ccx: &CrateContext) -> String {
87 SaveIn(v) => format!("SaveIn({})", ccx.tn().val_to_string(v)),
88 Ignore => "Ignore".to_string()
93 /// This function is equivalent to `trans(bcx, expr).store_to_dest(dest)` but it may generate
94 /// better optimized LLVM code.
95 pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
98 -> Block<'blk, 'tcx> {
101 if bcx.tcx().adjustments.borrow().contains_key(&expr.id) {
102 // use trans, which may be less efficient but
103 // which will perform the adjustments:
104 let datum = unpack_datum!(bcx, trans(bcx, expr));
105 return datum.store_to_dest(bcx, dest, expr.id)
108 debug!("trans_into() expr={}", expr.repr(bcx.tcx()));
110 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
114 bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
116 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
117 let kind = ty::expr_kind(bcx.tcx(), expr);
119 ty::LvalueExpr | ty::RvalueDatumExpr => {
120 trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
122 ty::RvalueDpsExpr => {
123 trans_rvalue_dps_unadjusted(bcx, expr, dest)
125 ty::RvalueStmtExpr => {
126 trans_rvalue_stmt_unadjusted(bcx, expr)
130 bcx.fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id)
133 /// Translates an expression, returning a datum (and new block) encapsulating the result. When
134 /// possible, it is preferred to use `trans_into`, as that may avoid creating a temporary on the
136 pub fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
138 -> DatumBlock<'blk, 'tcx, Expr> {
139 debug!("trans(expr={})", bcx.expr_to_string(expr));
144 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
148 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
149 let datum = unpack_datum!(bcx, trans_unadjusted(bcx, expr));
150 let datum = unpack_datum!(bcx, apply_adjustments(bcx, expr, datum));
151 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id);
152 return DatumBlock::new(bcx, datum);
155 pub fn get_len(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
156 GEPi(bcx, fat_ptr, &[0u, abi::FAT_PTR_EXTRA])
159 pub fn get_dataptr(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
160 GEPi(bcx, fat_ptr, &[0u, abi::FAT_PTR_ADDR])
163 /// Helper for trans that apply adjustments from `expr` to `datum`, which should be the unadjusted
164 /// translation of `expr`.
165 fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
167 datum: Datum<'tcx, Expr>)
168 -> DatumBlock<'blk, 'tcx, Expr> {
170 let mut datum = datum;
171 let adjustment = match bcx.tcx().adjustments.borrow().get(&expr.id).cloned() {
173 return DatumBlock::new(bcx, datum);
177 debug!("unadjusted datum for expr {}: {}, adjustment={}",
178 expr.repr(bcx.tcx()),
179 datum.to_string(bcx.ccx()),
180 adjustment.repr(bcx.tcx()));
182 AdjustAddEnv(..) => {
183 datum = unpack_datum!(bcx, add_env(bcx, expr, datum));
185 AdjustDerefRef(ref adj) => {
186 let (autoderefs, use_autoref) = match adj.autoref {
187 // Extracting a value from a box counts as a deref, but if we are
188 // just converting Box<[T, ..n]> to Box<[T]> we aren't really doing
189 // a deref (and wouldn't if we could treat Box like a normal struct).
190 Some(ty::AutoUnsizeUniq(..)) => (adj.autoderefs - 1, true),
191 // We are a bit paranoid about adjustments and thus might have a re-
192 // borrow here which merely derefs and then refs again (it might have
193 // a different region or mutability, but we don't care here. It might
194 // also be just in case we need to unsize. But if there are no nested
195 // adjustments then it should be a no-op).
196 Some(ty::AutoPtr(_, _, None)) if adj.autoderefs == 1 => {
198 // Don't skip a conversion from Box<T> to &T, etc.
200 let method_call = MethodCall::autoderef(expr.id, adj.autoderefs-1);
201 let method = bcx.tcx().method_map.borrow().get(&method_call).is_some();
203 // Don't skip an overloaded deref.
204 (adj.autoderefs, true)
206 (adj.autoderefs - 1, false)
209 _ => (adj.autoderefs, true),
212 _ => (adj.autoderefs, true)
217 let lval = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "auto_deref", expr.id));
218 datum = unpack_datum!(
219 bcx, deref_multiple(bcx, expr, lval.to_expr_datum(), autoderefs));
222 // (You might think there is a more elegant way to do this than a
223 // use_autoref bool, but then you remember that the borrow checker exists).
224 if let (true, &Some(ref a)) = (use_autoref, &adj.autoref) {
225 datum = unpack_datum!(bcx, apply_autoref(a,
232 debug!("after adjustments, datum={}", datum.to_string(bcx.ccx()));
233 return DatumBlock::new(bcx, datum);
235 fn apply_autoref<'blk, 'tcx>(autoref: &ty::AutoRef<'tcx>,
236 bcx: Block<'blk, 'tcx>,
238 datum: Datum<'tcx, Expr>)
239 -> DatumBlock<'blk, 'tcx, Expr> {
241 let mut datum = datum;
243 let datum = match autoref {
244 &AutoPtr(_, _, ref a) | &AutoUnsafe(_, ref a) => {
247 &Some(box ref a) => {
248 datum = unpack_datum!(bcx, apply_autoref(a, bcx, expr, datum));
252 unpack_datum!(bcx, ref_ptr(bcx, expr, datum))
254 &ty::AutoUnsize(ref k) => {
255 debug!(" AutoUnsize");
256 unpack_datum!(bcx, unsize_expr(bcx, expr, datum, k))
259 &ty::AutoUnsizeUniq(ty::UnsizeLength(len)) => {
260 debug!(" AutoUnsizeUniq(UnsizeLength)");
261 unpack_datum!(bcx, unsize_unique_vec(bcx, expr, datum, len))
263 &ty::AutoUnsizeUniq(ref k) => {
264 debug!(" AutoUnsizeUniq");
265 unpack_datum!(bcx, unsize_unique_expr(bcx, expr, datum, k))
269 DatumBlock::new(bcx, datum)
272 fn ref_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
274 datum: Datum<'tcx, Expr>)
275 -> DatumBlock<'blk, 'tcx, Expr> {
276 debug!("ref_ptr(expr={}, datum={})",
277 expr.repr(bcx.tcx()),
278 datum.to_string(bcx.ccx()));
280 if !ty::type_is_sized(bcx.tcx(), datum.ty) {
281 debug!("Taking address of unsized type {}",
282 bcx.ty_to_string(datum.ty));
283 ref_fat_ptr(bcx, expr, datum)
285 debug!("Taking address of sized type {}",
286 bcx.ty_to_string(datum.ty));
287 auto_ref(bcx, datum, expr)
291 // Retrieve the information we are losing (making dynamic) in an unsizing
293 // When making a dtor, we need to do different things depending on the
294 // ownership of the object.. mk_ty is a function for turning `unadjusted_ty`
295 // into a type to be destructed. If we want to end up with a Box pointer,
296 // then mk_ty should make a Box pointer (T -> Box<T>), if we want a
297 // borrowed reference then it should be T -> &T.
298 fn unsized_info<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
299 kind: &ty::UnsizeKind<'tcx>,
301 unadjusted_ty: Ty<'tcx>,
302 mk_ty: |Ty<'tcx>| -> Ty<'tcx>) -> ValueRef {
303 debug!("unsized_info(kind={}, id={}, unadjusted_ty={})",
304 kind, id, unadjusted_ty.repr(bcx.tcx()));
306 &ty::UnsizeLength(len) => C_uint(bcx.ccx(), len),
307 &ty::UnsizeStruct(box ref k, tp_index) => match unadjusted_ty.sty {
308 ty::ty_struct(_, ref substs) => {
309 let ty_substs = substs.types.get_slice(subst::TypeSpace);
310 // The dtor for a field treats it like a value, so mk_ty
311 // should just be the identity function.
312 unsized_info(bcx, k, id, ty_substs[tp_index], |t| t)
314 _ => bcx.sess().bug(format!("UnsizeStruct with bad sty: {}",
315 bcx.ty_to_string(unadjusted_ty)).as_slice())
317 &ty::UnsizeVtable(ty::TyTrait { ref principal, .. }, _) => {
318 let substs = principal.substs.with_self_ty(unadjusted_ty).erase_regions();
320 Rc::new(ty::TraitRef { def_id: principal.def_id,
322 let trait_ref = trait_ref.subst(bcx.tcx(), bcx.fcx.param_substs);
323 let box_ty = mk_ty(unadjusted_ty);
325 meth::get_vtable(bcx, box_ty, trait_ref),
326 Type::vtable_ptr(bcx.ccx()))
331 fn unsize_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
333 datum: Datum<'tcx, Expr>,
334 k: &ty::UnsizeKind<'tcx>)
335 -> DatumBlock<'blk, 'tcx, Expr> {
337 let datum_ty = datum.ty;
338 let unsized_ty = ty::unsize_ty(tcx, datum_ty, k, expr.span);
339 debug!("unsized_ty={}", unsized_ty.repr(bcx.tcx()));
340 let dest_ty = ty::mk_open(tcx, unsized_ty);
341 debug!("dest_ty={}", unsized_ty.repr(bcx.tcx()));
342 // Closures for extracting and manipulating the data and payload parts of
345 &ty::UnsizeStruct(..) =>
346 |bcx, val| PointerCast(bcx,
348 type_of::type_of(bcx.ccx(), unsized_ty).ptr_to()),
349 &ty::UnsizeLength(..) =>
350 |bcx, val| GEPi(bcx, val, &[0u, 0u]),
351 &ty::UnsizeVtable(..) =>
352 |_bcx, val| PointerCast(bcx, val, Type::i8p(bcx.ccx()))
354 let info = |bcx, _val| unsized_info(bcx,
362 mutbl: ast::MutImmutable
364 into_fat_ptr(bcx, expr, datum, dest_ty, base, info)
367 fn ref_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
369 datum: Datum<'tcx, Expr>)
370 -> DatumBlock<'blk, 'tcx, Expr> {
372 let dest_ty = ty::close_type(tcx, datum.ty);
373 let base = |bcx, val| Load(bcx, get_dataptr(bcx, val));
374 let len = |bcx, val| Load(bcx, get_len(bcx, val));
375 into_fat_ptr(bcx, expr, datum, dest_ty, base, len)
378 fn into_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
380 datum: Datum<'tcx, Expr>,
382 base: |Block<'blk, 'tcx>, ValueRef| -> ValueRef,
383 info: |Block<'blk, 'tcx>, ValueRef| -> ValueRef)
384 -> DatumBlock<'blk, 'tcx, Expr> {
388 let lval = unpack_datum!(bcx,
389 datum.to_lvalue_datum(bcx, "into_fat_ptr", expr.id));
390 let base = base(bcx, lval.val);
391 let info = info(bcx, lval.val);
393 let scratch = rvalue_scratch_datum(bcx, dest_ty, "__fat_ptr");
394 Store(bcx, base, get_dataptr(bcx, scratch.val));
395 Store(bcx, info, get_len(bcx, scratch.val));
397 DatumBlock::new(bcx, scratch.to_expr_datum())
400 fn unsize_unique_vec<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
402 datum: Datum<'tcx, Expr>,
404 -> DatumBlock<'blk, 'tcx, Expr> {
408 let datum_ty = datum.ty;
410 let lval = unpack_datum!(bcx,
411 datum.to_lvalue_datum(bcx, "unsize_unique_vec", expr.id));
413 let ll_len = C_uint(bcx.ccx(), len);
414 let unit_ty = ty::sequence_element_type(tcx, ty::type_content(datum_ty));
415 let vec_ty = ty::mk_uniq(tcx, ty::mk_vec(tcx, unit_ty, None));
416 let scratch = rvalue_scratch_datum(bcx, vec_ty, "__unsize_unique");
418 let base = get_dataptr(bcx, scratch.val);
419 let base = PointerCast(bcx,
421 type_of::type_of(bcx.ccx(), datum_ty).ptr_to());
422 bcx = lval.store_to(bcx, base);
424 Store(bcx, ll_len, get_len(bcx, scratch.val));
425 DatumBlock::new(bcx, scratch.to_expr_datum())
428 fn unsize_unique_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
430 datum: Datum<'tcx, Expr>,
431 k: &ty::UnsizeKind<'tcx>)
432 -> DatumBlock<'blk, 'tcx, Expr> {
436 let datum_ty = datum.ty;
437 let unboxed_ty = match datum_ty.sty {
439 _ => bcx.sess().bug(format!("Expected ty_uniq, found {}",
440 bcx.ty_to_string(datum_ty)).as_slice())
442 let result_ty = ty::mk_uniq(tcx, ty::unsize_ty(tcx, unboxed_ty, k, expr.span));
444 let lval = unpack_datum!(bcx,
445 datum.to_lvalue_datum(bcx, "unsize_unique_expr", expr.id));
447 let scratch = rvalue_scratch_datum(bcx, result_ty, "__uniq_fat_ptr");
448 let llbox_ty = type_of::type_of(bcx.ccx(), datum_ty);
449 let base = PointerCast(bcx, get_dataptr(bcx, scratch.val), llbox_ty.ptr_to());
450 bcx = lval.store_to(bcx, base);
452 let info = unsized_info(bcx, k, expr.id, unboxed_ty, |t| ty::mk_uniq(tcx, t));
453 Store(bcx, info, get_len(bcx, scratch.val));
455 let scratch = unpack_datum!(bcx,
456 scratch.to_expr_datum().to_lvalue_datum(bcx,
457 "fresh_uniq_fat_ptr",
460 DatumBlock::new(bcx, scratch.to_expr_datum())
463 fn add_env<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
465 datum: Datum<'tcx, Expr>)
466 -> DatumBlock<'blk, 'tcx, Expr> {
467 // This is not the most efficient thing possible; since closures
468 // are two words it'd be better if this were compiled in
469 // 'dest' mode, but I can't find a nice way to structure the
470 // code and keep it DRY that accommodates that use case at the
473 let closure_ty = expr_ty_adjusted(bcx, expr);
474 let fn_ptr = datum.to_llscalarish(bcx);
475 let def = ty::resolve_expr(bcx.tcx(), expr);
476 closure::make_closure_from_bare_fn(bcx, closure_ty, def, fn_ptr)
480 /// Translates an expression in "lvalue" mode -- meaning that it returns a reference to the memory
481 /// that the expr represents.
483 /// If this expression is an rvalue, this implies introducing a temporary. In other words,
484 /// something like `x().f` is translated into roughly the equivalent of
486 /// { tmp = x(); tmp.f }
487 pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
490 -> DatumBlock<'blk, 'tcx, Lvalue> {
492 let datum = unpack_datum!(bcx, trans(bcx, expr));
493 return datum.to_lvalue_datum(bcx, name, expr.id);
496 /// A version of `trans` that ignores adjustments. You almost certainly do not want to call this
498 fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
500 -> DatumBlock<'blk, 'tcx, Expr> {
503 debug!("trans_unadjusted(expr={})", bcx.expr_to_string(expr));
504 let _indenter = indenter();
506 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
508 return match ty::expr_kind(bcx.tcx(), expr) {
509 ty::LvalueExpr | ty::RvalueDatumExpr => {
510 let datum = unpack_datum!(bcx, {
511 trans_datum_unadjusted(bcx, expr)
514 DatumBlock {bcx: bcx, datum: datum}
517 ty::RvalueStmtExpr => {
518 bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
519 nil(bcx, expr_ty(bcx, expr))
522 ty::RvalueDpsExpr => {
523 let ty = expr_ty(bcx, expr);
524 if type_is_zero_size(bcx.ccx(), ty) {
525 bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
528 let scratch = rvalue_scratch_datum(bcx, ty, "");
529 bcx = trans_rvalue_dps_unadjusted(
530 bcx, expr, SaveIn(scratch.val));
532 // Note: this is not obviously a good idea. It causes
533 // immediate values to be loaded immediately after a
534 // return from a call or other similar expression,
535 // which in turn leads to alloca's having shorter
536 // lifetimes and hence larger stack frames. However,
537 // in turn it can lead to more register pressure.
538 // Still, in practice it seems to increase
539 // performance, since we have fewer problems with
541 let scratch = unpack_datum!(
542 bcx, scratch.to_appropriate_datum(bcx));
544 DatumBlock::new(bcx, scratch.to_expr_datum())
549 fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: Ty<'tcx>)
550 -> DatumBlock<'blk, 'tcx, Expr> {
551 let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
552 let datum = immediate_rvalue(llval, ty);
553 DatumBlock::new(bcx, datum.to_expr_datum())
557 fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
559 -> DatumBlock<'blk, 'tcx, Expr> {
562 let _icx = push_ctxt("trans_datum_unadjusted");
565 ast::ExprParen(ref e) => {
568 ast::ExprPath(_) => {
569 trans_def(bcx, expr, bcx.def(expr.id))
571 ast::ExprField(ref base, ident) => {
572 trans_rec_field(bcx, &**base, ident.node)
574 ast::ExprTupField(ref base, idx) => {
575 trans_rec_tup_field(bcx, &**base, idx.node)
577 ast::ExprIndex(ref base, ref idx) => {
578 trans_index(bcx, expr, &**base, &**idx, MethodCall::expr(expr.id))
580 ast::ExprSlice(ref base, ref start, ref end, _) => {
581 let _icx = push_ctxt("trans_slice");
584 let method_call = MethodCall::expr(expr.id);
585 let method_ty = ccx.tcx()
589 .map(|method| method.ty);
590 let base_datum = unpack_datum!(bcx, trans(bcx, &**base));
592 let mut args = vec![];
593 start.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
594 end.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
596 let result_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty.unwrap())).unwrap();
597 let scratch = rvalue_scratch_datum(bcx, result_ty, "trans_slice");
600 trans_overloaded_op(bcx,
605 Some(SaveIn(scratch.val))));
606 DatumBlock::new(bcx, scratch.to_expr_datum())
608 ast::ExprBox(_, ref contents) => {
609 // Special case for `Box<T>`
610 let box_ty = expr_ty(bcx, expr);
611 let contents_ty = expr_ty(bcx, &**contents);
614 trans_uniq_expr(bcx, box_ty, &**contents, contents_ty)
616 _ => bcx.sess().span_bug(expr.span,
617 "expected unique box")
621 ast::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &**lit),
622 ast::ExprBinary(op, ref lhs, ref rhs) => {
623 trans_binary(bcx, expr, op, &**lhs, &**rhs)
625 ast::ExprUnary(op, ref x) => {
626 trans_unary(bcx, expr, op, &**x)
628 ast::ExprAddrOf(_, ref x) => {
630 ast::ExprRepeat(..) | ast::ExprVec(..) => {
631 // Special case for slices.
632 let cleanup_debug_loc =
633 debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
637 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
638 let datum = unpack_datum!(
639 bcx, tvec::trans_slice_vec(bcx, expr, &**x));
640 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
641 DatumBlock::new(bcx, datum)
644 trans_addr_of(bcx, expr, &**x)
648 ast::ExprCast(ref val, _) => {
649 // Datum output mode means this is a scalar cast:
650 trans_imm_cast(bcx, &**val, expr.id)
653 bcx.tcx().sess.span_bug(
655 format!("trans_rvalue_datum_unadjusted reached \
656 fall-through case: {}",
657 expr.node).as_slice());
662 fn trans_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
664 get_idx: |&'blk ty::ctxt<'tcx>, &[ty::field<'tcx>]| -> uint)
665 -> DatumBlock<'blk, 'tcx, Expr> {
667 let _icx = push_ctxt("trans_rec_field");
669 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
670 let bare_ty = ty::unopen_type(base_datum.ty);
671 let repr = adt::represent_type(bcx.ccx(), bare_ty);
672 with_field_tys(bcx.tcx(), bare_ty, None, |discr, field_tys| {
673 let ix = get_idx(bcx.tcx(), field_tys);
674 let d = base_datum.get_element(
677 |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, ix));
679 if ty::type_is_sized(bcx.tcx(), d.ty) {
680 DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
682 let scratch = rvalue_scratch_datum(bcx, ty::mk_open(bcx.tcx(), d.ty), "");
683 Store(bcx, d.val, get_dataptr(bcx, scratch.val));
684 let info = Load(bcx, get_len(bcx, base_datum.val));
685 Store(bcx, info, get_len(bcx, scratch.val));
687 DatumBlock::new(bcx, scratch.to_expr_datum())
694 /// Translates `base.field`.
695 fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
698 -> DatumBlock<'blk, 'tcx, Expr> {
699 trans_field(bcx, base, |tcx, field_tys| ty::field_idx_strict(tcx, field.name, field_tys))
702 /// Translates `base.<idx>`.
703 fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
706 -> DatumBlock<'blk, 'tcx, Expr> {
707 trans_field(bcx, base, |_, _| idx)
710 fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
711 index_expr: &ast::Expr,
714 method_call: MethodCall)
715 -> DatumBlock<'blk, 'tcx, Expr> {
716 //! Translates `base[idx]`.
718 let _icx = push_ctxt("trans_index");
722 // Check for overloaded index.
723 let method_ty = ccx.tcx()
727 .map(|method| method.ty);
728 let elt_datum = match method_ty {
730 let base_datum = unpack_datum!(bcx, trans(bcx, base));
732 // Translate index expression.
733 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
735 let ref_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty)).unwrap();
736 let elt_ty = match ty::deref(ref_ty, true) {
738 bcx.tcx().sess.span_bug(index_expr.span,
739 "index method didn't return a \
740 dereferenceable type?!")
742 Some(elt_tm) => elt_tm.ty,
745 // Overloaded. Evaluate `trans_overloaded_op`, which will
746 // invoke the user's index() method, which basically yields
747 // a `&T` pointer. We can then proceed down the normal
748 // path (below) to dereference that `&T`.
749 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_index_elt");
751 trans_overloaded_op(bcx,
755 vec![(ix_datum, idx.id)],
756 Some(SaveIn(scratch.val))));
757 let datum = scratch.to_expr_datum();
758 if ty::type_is_sized(bcx.tcx(), elt_ty) {
759 Datum::new(datum.to_llscalarish(bcx), elt_ty, LvalueExpr)
761 Datum::new(datum.val, ty::mk_open(bcx.tcx(), elt_ty), LvalueExpr)
765 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
769 // Translate index expression and cast to a suitable LLVM integer.
770 // Rust is less strict than LLVM in this regard.
771 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
772 let ix_val = ix_datum.to_llscalarish(bcx);
773 let ix_size = machine::llbitsize_of_real(bcx.ccx(),
775 let int_size = machine::llbitsize_of_real(bcx.ccx(),
778 if ix_size < int_size {
779 if ty::type_is_signed(expr_ty(bcx, idx)) {
780 SExt(bcx, ix_val, ccx.int_type())
781 } else { ZExt(bcx, ix_val, ccx.int_type()) }
782 } else if ix_size > int_size {
783 Trunc(bcx, ix_val, ccx.int_type())
791 ty::sequence_element_type(bcx.tcx(),
793 base::maybe_name_value(bcx.ccx(), vt.llunit_size, "unit_sz");
795 let (base, len) = base_datum.get_vec_base_and_len(bcx);
797 debug!("trans_index: base {}", bcx.val_to_string(base));
798 debug!("trans_index: len {}", bcx.val_to_string(len));
800 let bounds_check = ICmp(bcx, llvm::IntUGE, ix_val, len);
801 let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
802 let expected = Call(bcx,
804 &[bounds_check, C_bool(ccx, false)],
806 bcx = with_cond(bcx, expected, |bcx| {
807 controlflow::trans_fail_bounds_check(bcx,
812 let elt = InBoundsGEP(bcx, base, &[ix_val]);
813 let elt = PointerCast(bcx, elt, vt.llunit_ty.ptr_to());
814 Datum::new(elt, vt.unit_ty, LvalueExpr)
818 DatumBlock::new(bcx, elt_datum)
821 fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
822 ref_expr: &ast::Expr,
824 -> DatumBlock<'blk, 'tcx, Expr> {
825 //! Translates a reference to a path.
827 let _icx = push_ctxt("trans_def_lvalue");
829 def::DefFn(..) | def::DefStaticMethod(..) | def::DefMethod(..) |
830 def::DefStruct(_) | def::DefVariant(..) => {
831 trans_def_fn_unadjusted(bcx, ref_expr, def)
833 def::DefStatic(did, _) => {
834 // There are two things that may happen here:
835 // 1) If the static item is defined in this crate, it will be
836 // translated using `get_item_val`, and we return a pointer to
838 // 2) If the static item is defined in another crate then we add
839 // (or reuse) a declaration of an external global, and return a
841 let const_ty = expr_ty(bcx, ref_expr);
843 fn get_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, did: ast::DefId,
844 const_ty: Ty<'tcx>) -> ValueRef {
845 // For external constants, we don't inline.
846 if did.krate == ast::LOCAL_CRATE {
849 // The LLVM global has the type of its initializer,
850 // which may not be equal to the enum's type for
852 let val = base::get_item_val(bcx.ccx(), did.node);
853 let pty = type_of::type_of(bcx.ccx(), const_ty).ptr_to();
854 PointerCast(bcx, val, pty)
857 base::get_extern_const(bcx.ccx(), did, const_ty)
860 let val = get_val(bcx, did, const_ty);
861 DatumBlock::new(bcx, Datum::new(val, const_ty, LvalueExpr))
863 def::DefConst(did) => {
864 // First, inline any external constants into the local crate so we
865 // can be sure to get the LLVM value corresponding to it.
866 let did = inline::maybe_instantiate_inline(bcx.ccx(), did);
867 if did.krate != ast::LOCAL_CRATE {
868 bcx.tcx().sess.span_bug(ref_expr.span,
869 "cross crate constant could not \
872 let val = base::get_item_val(bcx.ccx(), did.node);
874 // Next, we need to crate a ByRef rvalue datum to return. We can't
875 // use the normal .to_ref_datum() function because the type of
876 // `val` is not actually the same as `const_ty`.
878 // To get around this, we make a custom alloca slot with the
879 // appropriate type (const_ty), and then we cast it to a pointer of
880 // typeof(val), store the value, and then hand this slot over to
881 // the datum infrastructure.
882 let const_ty = expr_ty(bcx, ref_expr);
883 let llty = type_of::type_of(bcx.ccx(), const_ty);
884 let slot = alloca(bcx, llty, "const");
885 let pty = Type::from_ref(unsafe { llvm::LLVMTypeOf(val) }).ptr_to();
886 Store(bcx, val, PointerCast(bcx, slot, pty));
888 let datum = Datum::new(slot, const_ty, Rvalue::new(ByRef));
889 DatumBlock::new(bcx, datum.to_expr_datum())
892 DatumBlock::new(bcx, trans_local_var(bcx, def).to_expr_datum())
897 fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
899 -> Block<'blk, 'tcx> {
901 let _icx = push_ctxt("trans_rvalue_stmt");
903 if bcx.unreachable.get() {
907 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
910 ast::ExprParen(ref e) => {
911 trans_into(bcx, &**e, Ignore)
913 ast::ExprBreak(label_opt) => {
914 controlflow::trans_break(bcx, expr.id, label_opt)
916 ast::ExprAgain(label_opt) => {
917 controlflow::trans_cont(bcx, expr.id, label_opt)
919 ast::ExprRet(ref ex) => {
920 controlflow::trans_ret(bcx, ex.as_ref().map(|e| &**e))
922 ast::ExprWhile(ref cond, ref body, _) => {
923 controlflow::trans_while(bcx, expr.id, &**cond, &**body)
925 ast::ExprForLoop(ref pat, ref head, ref body, _) => {
926 controlflow::trans_for(bcx,
932 ast::ExprLoop(ref body, _) => {
933 controlflow::trans_loop(bcx, expr.id, &**body)
935 ast::ExprAssign(ref dst, ref src) => {
936 let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
937 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &**dst, "assign"));
939 if ty::type_needs_drop(bcx.tcx(), dst_datum.ty) {
940 // If there are destructors involved, make sure we
941 // are copying from an rvalue, since that cannot possible
942 // alias an lvalue. We are concerned about code like:
950 // where e.g. a : Option<Foo> and a.b :
951 // Option<Foo>. In that case, freeing `a` before the
952 // assignment may also free `a.b`!
954 // We could avoid this intermediary with some analysis
955 // to determine whether `dst` may possibly own `src`.
956 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
957 let src_datum = unpack_datum!(
958 bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
959 bcx = glue::drop_ty(bcx,
962 Some(NodeInfo { id: expr.id, span: expr.span }));
963 src_datum.store_to(bcx, dst_datum.val)
965 src_datum.store_to(bcx, dst_datum.val)
968 ast::ExprAssignOp(op, ref dst, ref src) => {
969 trans_assign_op(bcx, expr, op, &**dst, &**src)
971 ast::ExprInlineAsm(ref a) => {
972 asm::trans_inline_asm(bcx, a)
975 bcx.tcx().sess.span_bug(
977 format!("trans_rvalue_stmt_unadjusted reached \
978 fall-through case: {}",
979 expr.node).as_slice());
984 fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
987 -> Block<'blk, 'tcx> {
988 let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
992 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
995 ast::ExprParen(ref e) => {
996 trans_into(bcx, &**e, dest)
998 ast::ExprPath(_) => {
999 trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
1001 ast::ExprIf(ref cond, ref thn, ref els) => {
1002 controlflow::trans_if(bcx, expr.id, &**cond, &**thn, els.as_ref().map(|e| &**e), dest)
1004 ast::ExprMatch(ref discr, ref arms, _) => {
1005 _match::trans_match(bcx, expr, &**discr, arms.as_slice(), dest)
1007 ast::ExprBlock(ref blk) => {
1008 controlflow::trans_block(bcx, &**blk, dest)
1010 ast::ExprStruct(_, ref fields, ref base) => {
1013 base.as_ref().map(|e| &**e),
1018 ast::ExprTup(ref args) => {
1019 let numbered_fields: Vec<(uint, &ast::Expr)> =
1020 args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
1024 numbered_fields.as_slice(),
1027 Some(NodeInfo { id: expr.id, span: expr.span }))
1029 ast::ExprLit(ref lit) => {
1031 ast::LitStr(ref s, _) => {
1032 tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
1037 .span_bug(expr.span,
1038 "trans_rvalue_dps_unadjusted shouldn't be \
1039 translating this type of literal")
1043 ast::ExprVec(..) | ast::ExprRepeat(..) => {
1044 tvec::trans_fixed_vstore(bcx, expr, dest)
1046 ast::ExprClosure(_, _, ref decl, ref body) |
1047 ast::ExprProc(ref decl, ref body) => {
1048 // Check the side-table to see whether this is an unboxed
1049 // closure or an older, legacy style closure. Store this
1050 // into a variable to ensure the the RefCell-lock is
1051 // released before we recurse.
1052 let is_unboxed_closure =
1053 bcx.tcx().unboxed_closures.borrow().contains_key(&ast_util::local_def(expr.id));
1054 if is_unboxed_closure {
1055 closure::trans_unboxed_closure(bcx, &**decl, &**body, expr.id, dest)
1057 let expr_ty = expr_ty(bcx, expr);
1058 let store = ty::ty_closure_store(expr_ty);
1059 debug!("translating block function {} with type {}",
1060 expr_to_string(expr), expr_ty.repr(tcx));
1061 closure::trans_expr_fn(bcx, store, &**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())
1114 let trait_ref = trait_ref.subst(bcx.tcx(), bcx.fcx.param_substs);
1115 let datum = unpack_datum!(bcx, trans(bcx, &**val));
1116 meth::trans_trait_cast(bcx, datum, expr.id,
1119 bcx.tcx().sess.span_bug(expr.span,
1120 "expr_cast of non-trait");
1123 ast::ExprAssignOp(op, ref dst, ref src) => {
1124 trans_assign_op(bcx, expr, op, &**dst, &**src)
1127 bcx.tcx().sess.span_bug(
1129 format!("trans_rvalue_dps_unadjusted reached fall-through \
1131 expr.node).as_slice());
1136 fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1137 ref_expr: &ast::Expr,
1140 -> Block<'blk, 'tcx> {
1141 let _icx = push_ctxt("trans_def_dps_unadjusted");
1143 let lldest = match dest {
1144 SaveIn(lldest) => lldest,
1145 Ignore => { return bcx; }
1149 def::DefVariant(tid, vid, _) => {
1150 let variant_info = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
1151 if variant_info.args.len() > 0u {
1153 let llfn = callee::trans_fn_ref(bcx, vid, ExprId(ref_expr.id));
1154 Store(bcx, llfn, lldest);
1158 let ty = expr_ty(bcx, ref_expr);
1159 let repr = adt::represent_type(bcx.ccx(), ty);
1160 adt::trans_set_discr(bcx, &*repr, lldest,
1161 variant_info.disr_val);
1165 def::DefStruct(_) => {
1166 let ty = expr_ty(bcx, ref_expr);
1168 ty::ty_struct(did, _) if ty::has_dtor(bcx.tcx(), did) => {
1169 let repr = adt::represent_type(bcx.ccx(), ty);
1170 adt::trans_set_discr(bcx, &*repr, lldest, 0);
1177 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1178 "Non-DPS def {} referened by {}",
1179 def, bcx.node_id_to_string(ref_expr.id)).as_slice());
1184 fn trans_def_fn_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1185 ref_expr: &ast::Expr,
1187 -> DatumBlock<'blk, 'tcx, Expr> {
1188 let _icx = push_ctxt("trans_def_datum_unadjusted");
1190 let llfn = match def {
1191 def::DefFn(did, _) |
1192 def::DefStruct(did) | def::DefVariant(_, did, _) |
1193 def::DefStaticMethod(did, def::FromImpl(_)) |
1194 def::DefMethod(did, _, def::FromImpl(_)) => {
1195 callee::trans_fn_ref(bcx, did, ExprId(ref_expr.id))
1197 def::DefStaticMethod(impl_did, def::FromTrait(trait_did)) |
1198 def::DefMethod(impl_did, _, def::FromTrait(trait_did)) => {
1199 meth::trans_static_method_callee(bcx, impl_did,
1200 trait_did, ref_expr.id)
1203 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1204 "trans_def_fn_unadjusted invoked on: {} for {}",
1206 ref_expr.repr(bcx.tcx())).as_slice());
1210 let fn_ty = expr_ty(bcx, ref_expr);
1211 DatumBlock::new(bcx, Datum::new(llfn, fn_ty, RvalueExpr(Rvalue::new(ByValue))))
1214 /// Translates a reference to a local variable or argument. This always results in an lvalue datum.
1215 pub fn trans_local_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1217 -> Datum<'tcx, Lvalue> {
1218 let _icx = push_ctxt("trans_local_var");
1221 def::DefUpvar(nid, _, _) => {
1222 // Can't move upvars, so this is never a ZeroMemLastUse.
1223 let local_ty = node_id_type(bcx, nid);
1224 match bcx.fcx.llupvars.borrow().get(&nid) {
1225 Some(&val) => Datum::new(val, local_ty, Lvalue),
1227 bcx.sess().bug(format!(
1228 "trans_local_var: no llval for upvar {} found",
1233 def::DefLocal(nid) => {
1234 let datum = match bcx.fcx.lllocals.borrow().get(&nid) {
1237 bcx.sess().bug(format!(
1238 "trans_local_var: no datum for local/arg {} found",
1242 debug!("take_local(nid={}, v={}, ty={})",
1243 nid, bcx.val_to_string(datum.val), bcx.ty_to_string(datum.ty));
1247 bcx.sess().unimpl(format!(
1248 "unsupported def type in trans_local_var: {}",
1254 /// Helper for enumerating the field types of structs, enums, or records. The optional node ID here
1255 /// is the node ID of the path identifying the enum variant in use. If none, this cannot possibly
1256 /// an enum variant (so, if it is and `node_id_opt` is none, this function panics).
1257 pub fn with_field_tys<'tcx, R>(tcx: &ty::ctxt<'tcx>,
1259 node_id_opt: Option<ast::NodeId>,
1260 op: |ty::Disr, (&[ty::field<'tcx>])| -> R)
1263 ty::ty_struct(did, ref substs) => {
1264 op(0, struct_fields(tcx, did, substs).as_slice())
1267 ty::ty_tup(ref v) => {
1268 op(0, tup_fields(v.as_slice()).as_slice())
1271 ty::ty_enum(_, ref substs) => {
1272 // We want the *variant* ID here, not the enum ID.
1275 tcx.sess.bug(format!(
1276 "cannot get field types from the enum type {} \
1278 ty.repr(tcx)).as_slice());
1281 let def = tcx.def_map.borrow()[node_id].clone();
1283 def::DefVariant(enum_id, variant_id, _) => {
1284 let variant_info = ty::enum_variant_with_id(
1285 tcx, enum_id, variant_id);
1286 op(variant_info.disr_val,
1292 tcx.sess.bug("resolve didn't map this expr to a \
1301 tcx.sess.bug(format!(
1302 "cannot get field types from the type {}",
1303 ty.repr(tcx)).as_slice());
1308 fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1309 fields: &[ast::Field],
1310 base: Option<&ast::Expr>,
1311 expr_span: codemap::Span,
1312 expr_id: ast::NodeId,
1313 dest: Dest) -> Block<'blk, 'tcx> {
1314 let _icx = push_ctxt("trans_rec");
1316 let ty = node_id_type(bcx, expr_id);
1317 let tcx = bcx.tcx();
1318 with_field_tys(tcx, ty, Some(expr_id), |discr, field_tys| {
1319 let mut need_base = Vec::from_elem(field_tys.len(), true);
1321 let numbered_fields = fields.iter().map(|field| {
1323 field_tys.iter().position(|field_ty|
1324 field_ty.name == field.ident.node.name);
1327 need_base[i] = false;
1331 tcx.sess.span_bug(field.span,
1332 "Couldn't find field in struct type")
1335 }).collect::<Vec<_>>();
1336 let optbase = match base {
1337 Some(base_expr) => {
1338 let mut leftovers = Vec::new();
1339 for (i, b) in need_base.iter().enumerate() {
1341 leftovers.push((i, field_tys[i].mt.ty))
1344 Some(StructBaseInfo {expr: base_expr,
1345 fields: leftovers })
1348 if need_base.iter().any(|b| *b) {
1349 tcx.sess.span_bug(expr_span, "missing fields and no base expr")
1358 numbered_fields.as_slice(),
1361 Some(NodeInfo { id: expr_id, span: expr_span }))
1365 /// Information that `trans_adt` needs in order to fill in the fields
1366 /// of a struct copied from a base struct (e.g., from an expression
1367 /// like `Foo { a: b, ..base }`.
1369 /// Note that `fields` may be empty; the base expression must always be
1370 /// evaluated for side-effects.
1371 pub struct StructBaseInfo<'a, 'tcx> {
1372 /// The base expression; will be evaluated after all explicit fields.
1373 expr: &'a ast::Expr,
1374 /// The indices of fields to copy paired with their types.
1375 fields: Vec<(uint, Ty<'tcx>)>
1378 /// Constructs an ADT instance:
1380 /// - `fields` should be a list of field indices paired with the
1381 /// expression to store into that field. The initializers will be
1382 /// evaluated in the order specified by `fields`.
1384 /// - `optbase` contains information on the base struct (if any) from
1385 /// which remaining fields are copied; see comments on `StructBaseInfo`.
1386 pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1389 fields: &[(uint, &ast::Expr)],
1390 optbase: Option<StructBaseInfo<'a, 'tcx>>,
1392 source_location: Option<NodeInfo>)
1393 -> Block<'blk, 'tcx> {
1394 let _icx = push_ctxt("trans_adt");
1396 let repr = adt::represent_type(bcx.ccx(), ty);
1398 match source_location {
1399 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1405 // If we don't care about the result, just make a
1406 // temporary stack slot
1407 let addr = match dest {
1409 Ignore => alloc_ty(bcx, ty, "temp"),
1412 // This scope holds intermediates that must be cleaned should
1413 // panic occur before the ADT as a whole is ready.
1414 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1416 // First we trans the base, if we have one, to the dest
1417 for base in optbase.iter() {
1418 assert_eq!(discr, 0);
1420 match ty::expr_kind(bcx.tcx(), &*base.expr) {
1421 ty::RvalueDpsExpr | ty::RvalueDatumExpr if !ty::type_needs_drop(bcx.tcx(), ty) => {
1422 bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
1424 ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr"),
1426 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
1427 for &(i, t) in base.fields.iter() {
1428 let datum = base_datum.get_element(
1429 bcx, t, |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, i));
1430 assert!(ty::type_is_sized(bcx.tcx(), datum.ty));
1431 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1432 bcx = datum.store_to(bcx, dest);
1438 match source_location {
1439 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1445 if ty::type_is_simd(bcx.tcx(), ty) {
1446 // This is the constructor of a SIMD type, such types are
1447 // always primitive machine types and so do not have a
1448 // destructor or require any clean-up.
1449 let llty = type_of::type_of(bcx.ccx(), ty);
1451 // keep a vector as a register, and running through the field
1452 // `insertelement`ing them directly into that register
1453 // (i.e. avoid GEPi and `store`s to an alloca) .
1454 let mut vec_val = C_undef(llty);
1456 for &(i, ref e) in fields.iter() {
1457 let block_datum = trans(bcx, &**e);
1458 bcx = block_datum.bcx;
1459 let position = C_uint(bcx.ccx(), i);
1460 let value = block_datum.datum.to_llscalarish(bcx);
1461 vec_val = InsertElement(bcx, vec_val, value, position);
1463 Store(bcx, vec_val, addr);
1465 // Now, we just overwrite the fields we've explicitly specified
1466 for &(i, ref e) in fields.iter() {
1467 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1468 let e_ty = expr_ty_adjusted(bcx, &**e);
1469 bcx = trans_into(bcx, &**e, SaveIn(dest));
1470 let scope = cleanup::CustomScope(custom_cleanup_scope);
1471 fcx.schedule_lifetime_end(scope, dest);
1472 fcx.schedule_drop_mem(scope, dest, e_ty);
1476 adt::trans_set_discr(bcx, &*repr, addr, discr);
1478 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1480 // If we don't care about the result drop the temporary we made
1484 bcx = glue::drop_ty(bcx, addr, ty, source_location);
1485 base::call_lifetime_end(bcx, addr);
1492 fn trans_immediate_lit<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1495 -> DatumBlock<'blk, 'tcx, Expr> {
1496 // must not be a string constant, that is a RvalueDpsExpr
1497 let _icx = push_ctxt("trans_immediate_lit");
1498 let ty = expr_ty(bcx, expr);
1499 let v = consts::const_lit(bcx.ccx(), expr, lit);
1500 immediate_rvalue_bcx(bcx, v, ty).to_expr_datumblock()
1503 fn trans_unary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1506 sub_expr: &ast::Expr)
1507 -> DatumBlock<'blk, 'tcx, Expr> {
1508 let ccx = bcx.ccx();
1510 let _icx = push_ctxt("trans_unary_datum");
1512 let method_call = MethodCall::expr(expr.id);
1514 // The only overloaded operator that is translated to a datum
1515 // is an overloaded deref, since it is always yields a `&T`.
1516 // Otherwise, we should be in the RvalueDpsExpr path.
1518 op == ast::UnDeref ||
1519 !ccx.tcx().method_map.borrow().contains_key(&method_call));
1521 let un_ty = expr_ty(bcx, expr);
1525 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1526 let llresult = Not(bcx, datum.to_llscalarish(bcx));
1527 immediate_rvalue_bcx(bcx, llresult, un_ty).to_expr_datumblock()
1530 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1531 let val = datum.to_llscalarish(bcx);
1533 if ty::type_is_fp(un_ty) {
1539 immediate_rvalue_bcx(bcx, llneg, un_ty).to_expr_datumblock()
1542 trans_uniq_expr(bcx, un_ty, sub_expr, expr_ty(bcx, sub_expr))
1545 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1546 deref_once(bcx, expr, datum, method_call)
1551 fn trans_uniq_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1553 contents: &ast::Expr,
1554 contents_ty: Ty<'tcx>)
1555 -> DatumBlock<'blk, 'tcx, Expr> {
1556 let _icx = push_ctxt("trans_uniq_expr");
1558 assert!(ty::type_is_sized(bcx.tcx(), contents_ty));
1559 let llty = type_of::type_of(bcx.ccx(), contents_ty);
1560 let size = llsize_of(bcx.ccx(), llty);
1561 let align = C_uint(bcx.ccx(), type_of::align_of(bcx.ccx(), contents_ty));
1562 let llty_ptr = llty.ptr_to();
1563 let Result { bcx, val } = malloc_raw_dyn(bcx, llty_ptr, box_ty, size, align);
1564 // Unique boxes do not allocate for zero-size types. The standard library
1565 // may assume that `free` is never called on the pointer returned for
1566 // `Box<ZeroSizeType>`.
1567 let bcx = if llsize_of_alloc(bcx.ccx(), llty) == 0 {
1568 trans_into(bcx, contents, SaveIn(val))
1570 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1571 fcx.schedule_free_value(cleanup::CustomScope(custom_cleanup_scope),
1572 val, cleanup::HeapExchange, contents_ty);
1573 let bcx = trans_into(bcx, contents, SaveIn(val));
1574 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1577 immediate_rvalue_bcx(bcx, val, box_ty).to_expr_datumblock()
1580 fn trans_addr_of<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1582 subexpr: &ast::Expr)
1583 -> DatumBlock<'blk, 'tcx, Expr> {
1584 let _icx = push_ctxt("trans_addr_of");
1586 let sub_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, subexpr, "addr_of"));
1587 match sub_datum.ty.sty {
1589 // Opened DST value, close to a fat pointer
1590 debug!("Closing fat pointer {}", bcx.ty_to_string(sub_datum.ty));
1592 let scratch = rvalue_scratch_datum(bcx,
1593 ty::close_type(bcx.tcx(), sub_datum.ty),
1595 let base = Load(bcx, get_dataptr(bcx, sub_datum.val));
1596 Store(bcx, base, get_dataptr(bcx, scratch.val));
1598 let len = Load(bcx, get_len(bcx, sub_datum.val));
1599 Store(bcx, len, get_len(bcx, scratch.val));
1601 DatumBlock::new(bcx, scratch.to_expr_datum())
1604 // Sized value, ref to a thin pointer
1605 let ty = expr_ty(bcx, expr);
1606 immediate_rvalue_bcx(bcx, sub_datum.val, ty).to_expr_datumblock()
1611 // Important to get types for both lhs and rhs, because one might be _|_
1612 // and the other not.
1613 fn trans_eager_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1614 binop_expr: &ast::Expr,
1621 -> DatumBlock<'blk, 'tcx, Expr> {
1622 let _icx = push_ctxt("trans_eager_binop");
1624 let tcx = bcx.tcx();
1625 let is_simd = ty::type_is_simd(tcx, lhs_t);
1627 if is_simd { ty::simd_type(tcx, lhs_t) }
1630 let is_float = ty::type_is_fp(intype);
1631 let is_signed = ty::type_is_signed(intype);
1633 let rhs = base::cast_shift_expr_rhs(bcx, op, lhs, rhs);
1636 let val = match op {
1638 if is_float { FAdd(bcx, lhs, rhs) }
1639 else { Add(bcx, lhs, rhs) }
1642 if is_float { FSub(bcx, lhs, rhs) }
1643 else { Sub(bcx, lhs, rhs) }
1646 if is_float { FMul(bcx, lhs, rhs) }
1647 else { Mul(bcx, lhs, rhs) }
1653 // Only zero-check integers; fp /0 is NaN
1654 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1655 op, lhs, rhs, rhs_t);
1667 // Only zero-check integers; fp %0 is NaN
1668 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1669 op, lhs, rhs, rhs_t);
1677 ast::BiBitOr => Or(bcx, lhs, rhs),
1678 ast::BiBitAnd => And(bcx, lhs, rhs),
1679 ast::BiBitXor => Xor(bcx, lhs, rhs),
1680 ast::BiShl => Shl(bcx, lhs, rhs),
1684 } else { LShr(bcx, lhs, rhs) }
1686 ast::BiEq | ast::BiNe | ast::BiLt | ast::BiGe | ast::BiLe | ast::BiGt => {
1687 if ty::type_is_scalar(rhs_t) {
1688 unpack_result!(bcx, base::compare_scalar_types(bcx, lhs, rhs, rhs_t, op))
1690 base::compare_simd_types(bcx, lhs, rhs, intype, ty::simd_size(tcx, lhs_t), op)
1692 bcx.tcx().sess.span_bug(binop_expr.span, "comparison operator unsupported for type")
1696 bcx.tcx().sess.span_bug(binop_expr.span, "unexpected binop");
1700 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1703 // refinement types would obviate the need for this
1704 enum lazy_binop_ty {
1709 fn trans_lazy_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1710 binop_expr: &ast::Expr,
1714 -> DatumBlock<'blk, 'tcx, Expr> {
1715 let _icx = push_ctxt("trans_lazy_binop");
1716 let binop_ty = expr_ty(bcx, binop_expr);
1719 let DatumBlock {bcx: past_lhs, datum: lhs} = trans(bcx, a);
1720 let lhs = lhs.to_llscalarish(past_lhs);
1722 if past_lhs.unreachable.get() {
1723 return immediate_rvalue_bcx(past_lhs, lhs, binop_ty).to_expr_datumblock();
1726 let join = fcx.new_id_block("join", binop_expr.id);
1727 let before_rhs = fcx.new_id_block("before_rhs", b.id);
1730 lazy_and => CondBr(past_lhs, lhs, before_rhs.llbb, join.llbb),
1731 lazy_or => CondBr(past_lhs, lhs, join.llbb, before_rhs.llbb)
1734 let DatumBlock {bcx: past_rhs, datum: rhs} = trans(before_rhs, b);
1735 let rhs = rhs.to_llscalarish(past_rhs);
1737 if past_rhs.unreachable.get() {
1738 return immediate_rvalue_bcx(join, lhs, binop_ty).to_expr_datumblock();
1741 Br(past_rhs, join.llbb);
1742 let phi = Phi(join, Type::i1(bcx.ccx()), &[lhs, rhs],
1743 &[past_lhs.llbb, past_rhs.llbb]);
1745 return immediate_rvalue_bcx(join, phi, binop_ty).to_expr_datumblock();
1748 fn trans_binary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1753 -> DatumBlock<'blk, 'tcx, Expr> {
1754 let _icx = push_ctxt("trans_binary");
1755 let ccx = bcx.ccx();
1757 // if overloaded, would be RvalueDpsExpr
1758 assert!(!ccx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
1762 trans_lazy_binop(bcx, expr, lazy_and, lhs, rhs)
1765 trans_lazy_binop(bcx, expr, lazy_or, lhs, rhs)
1769 let lhs_datum = unpack_datum!(bcx, trans(bcx, lhs));
1770 let rhs_datum = unpack_datum!(bcx, trans(bcx, rhs));
1771 let binop_ty = expr_ty(bcx, expr);
1773 debug!("trans_binary (expr {}): lhs_datum={}",
1775 lhs_datum.to_string(ccx));
1776 let lhs_ty = lhs_datum.ty;
1777 let lhs = lhs_datum.to_llscalarish(bcx);
1779 debug!("trans_binary (expr {}): rhs_datum={}",
1781 rhs_datum.to_string(ccx));
1782 let rhs_ty = rhs_datum.ty;
1783 let rhs = rhs_datum.to_llscalarish(bcx);
1784 trans_eager_binop(bcx, expr, binop_ty, op,
1785 lhs_ty, lhs, rhs_ty, rhs)
1790 fn trans_overloaded_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1792 method_call: MethodCall,
1793 lhs: Datum<'tcx, Expr>,
1794 rhs: Vec<(Datum<'tcx, Expr>, ast::NodeId)>,
1796 -> Result<'blk, 'tcx> {
1797 let method_ty = (*bcx.tcx().method_map.borrow())[method_call].ty;
1798 callee::trans_call_inner(bcx,
1799 Some(expr_info(expr)),
1800 monomorphize_type(bcx, method_ty),
1801 |bcx, arg_cleanup_scope| {
1802 meth::trans_method_callee(bcx,
1807 callee::ArgOverloadedOp(lhs, rhs),
1811 fn trans_overloaded_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1813 callee: &'a ast::Expr,
1814 args: &'a [P<ast::Expr>],
1816 -> Block<'blk, 'tcx> {
1817 let method_call = MethodCall::expr(expr.id);
1818 let method_type = (*bcx.tcx()
1820 .borrow())[method_call]
1822 let mut all_args = vec!(callee);
1823 all_args.extend(args.iter().map(|e| &**e));
1825 callee::trans_call_inner(bcx,
1826 Some(expr_info(expr)),
1827 monomorphize_type(bcx,
1829 |bcx, arg_cleanup_scope| {
1830 meth::trans_method_callee(
1836 callee::ArgOverloadedCall(all_args),
1841 fn int_cast(bcx: Block,
1847 let _icx = push_ctxt("int_cast");
1849 let srcsz = llvm::LLVMGetIntTypeWidth(llsrctype.to_ref());
1850 let dstsz = llvm::LLVMGetIntTypeWidth(lldsttype.to_ref());
1851 return if dstsz == srcsz {
1852 BitCast(bcx, llsrc, lldsttype)
1853 } else if srcsz > dstsz {
1854 TruncOrBitCast(bcx, llsrc, lldsttype)
1856 SExtOrBitCast(bcx, llsrc, lldsttype)
1858 ZExtOrBitCast(bcx, llsrc, lldsttype)
1863 fn float_cast(bcx: Block,
1868 let _icx = push_ctxt("float_cast");
1869 let srcsz = llsrctype.float_width();
1870 let dstsz = lldsttype.float_width();
1871 return if dstsz > srcsz {
1872 FPExt(bcx, llsrc, lldsttype)
1873 } else if srcsz > dstsz {
1874 FPTrunc(bcx, llsrc, lldsttype)
1878 #[deriving(PartialEq, Show)]
1879 pub enum cast_kind {
1887 impl Copy for cast_kind {}
1889 pub fn cast_type_kind<'tcx>(tcx: &ty::ctxt<'tcx>, t: Ty<'tcx>) -> cast_kind {
1891 ty::ty_char => cast_integral,
1892 ty::ty_float(..) => cast_float,
1893 ty::ty_rptr(_, mt) | ty::ty_ptr(mt) => {
1894 if ty::type_is_sized(tcx, mt.ty) {
1900 ty::ty_bare_fn(..) => cast_pointer,
1901 ty::ty_int(..) => cast_integral,
1902 ty::ty_uint(..) => cast_integral,
1903 ty::ty_bool => cast_integral,
1904 ty::ty_enum(..) => cast_enum,
1909 fn cast_is_noop<'tcx>(t_in: Ty<'tcx>, t_out: Ty<'tcx>) -> bool {
1910 match (ty::deref(t_in, true), ty::deref(t_out, true)) {
1911 (Some(ty::mt{ ty: t_in, .. }), Some(ty::mt{ ty: t_out, .. })) => {
1918 fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1921 -> DatumBlock<'blk, 'tcx, Expr> {
1922 let _icx = push_ctxt("trans_cast");
1924 let ccx = bcx.ccx();
1926 let t_in = expr_ty(bcx, expr);
1927 let t_out = node_id_type(bcx, id);
1928 let k_in = cast_type_kind(bcx.tcx(), t_in);
1929 let k_out = cast_type_kind(bcx.tcx(), t_out);
1930 let s_in = k_in == cast_integral && ty::type_is_signed(t_in);
1931 let ll_t_in = type_of::arg_type_of(ccx, t_in);
1932 let ll_t_out = type_of::arg_type_of(ccx, t_out);
1934 // Convert the value to be cast into a ValueRef, either by-ref or
1935 // by-value as appropriate given its type:
1936 let mut datum = unpack_datum!(bcx, trans(bcx, expr));
1938 if cast_is_noop(datum.ty, t_out) {
1940 return DatumBlock::new(bcx, datum);
1943 let newval = match (k_in, k_out) {
1944 (cast_integral, cast_integral) => {
1945 let llexpr = datum.to_llscalarish(bcx);
1946 int_cast(bcx, ll_t_out, ll_t_in, llexpr, s_in)
1948 (cast_float, cast_float) => {
1949 let llexpr = datum.to_llscalarish(bcx);
1950 float_cast(bcx, ll_t_out, ll_t_in, llexpr)
1952 (cast_integral, cast_float) => {
1953 let llexpr = datum.to_llscalarish(bcx);
1955 SIToFP(bcx, llexpr, ll_t_out)
1956 } else { UIToFP(bcx, llexpr, ll_t_out) }
1958 (cast_float, cast_integral) => {
1959 let llexpr = datum.to_llscalarish(bcx);
1960 if ty::type_is_signed(t_out) {
1961 FPToSI(bcx, llexpr, ll_t_out)
1962 } else { FPToUI(bcx, llexpr, ll_t_out) }
1964 (cast_integral, cast_pointer) => {
1965 let llexpr = datum.to_llscalarish(bcx);
1966 IntToPtr(bcx, llexpr, ll_t_out)
1968 (cast_pointer, cast_integral) => {
1969 let llexpr = datum.to_llscalarish(bcx);
1970 PtrToInt(bcx, llexpr, ll_t_out)
1972 (cast_pointer, cast_pointer) => {
1973 let llexpr = datum.to_llscalarish(bcx);
1974 PointerCast(bcx, llexpr, ll_t_out)
1976 (cast_enum, cast_integral) |
1977 (cast_enum, cast_float) => {
1979 let repr = adt::represent_type(ccx, t_in);
1980 let datum = unpack_datum!(
1981 bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
1982 let llexpr_ptr = datum.to_llref();
1984 adt::trans_get_discr(bcx, &*repr, llexpr_ptr, Some(Type::i64(ccx)));
1986 cast_integral => int_cast(bcx, ll_t_out,
1987 val_ty(lldiscrim_a),
1989 cast_float => SIToFP(bcx, lldiscrim_a, ll_t_out),
1991 ccx.sess().bug(format!("translating unsupported cast: \
1992 {} ({}) -> {} ({})",
1993 t_in.repr(bcx.tcx()),
1995 t_out.repr(bcx.tcx()),
2000 _ => ccx.sess().bug(format!("translating unsupported cast: \
2001 {} ({}) -> {} ({})",
2002 t_in.repr(bcx.tcx()),
2004 t_out.repr(bcx.tcx()),
2007 return immediate_rvalue_bcx(bcx, newval, t_out).to_expr_datumblock();
2010 fn trans_assign_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2015 -> Block<'blk, 'tcx> {
2016 let _icx = push_ctxt("trans_assign_op");
2019 debug!("trans_assign_op(expr={})", bcx.expr_to_string(expr));
2021 // User-defined operator methods cannot be used with `+=` etc right now
2022 assert!(!bcx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
2024 // Evaluate LHS (destination), which should be an lvalue
2025 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, dst, "assign_op"));
2026 assert!(!ty::type_needs_drop(bcx.tcx(), dst_datum.ty));
2027 let dst_ty = dst_datum.ty;
2028 let dst = load_ty(bcx, dst_datum.val, dst_datum.ty);
2031 let rhs_datum = unpack_datum!(bcx, trans(bcx, &*src));
2032 let rhs_ty = rhs_datum.ty;
2033 let rhs = rhs_datum.to_llscalarish(bcx);
2035 // Perform computation and store the result
2036 let result_datum = unpack_datum!(
2037 bcx, trans_eager_binop(bcx, expr, dst_datum.ty, op,
2038 dst_ty, dst, rhs_ty, rhs));
2039 return result_datum.store_to(bcx, dst_datum.val);
2042 fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2043 datum: Datum<'tcx, Expr>,
2045 -> DatumBlock<'blk, 'tcx, Expr> {
2048 // Ensure cleanup of `datum` if not already scheduled and obtain
2049 // a "by ref" pointer.
2050 let lv_datum = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "autoref", expr.id));
2052 // Compute final type. Note that we are loose with the region and
2053 // mutability, since those things don't matter in trans.
2054 let referent_ty = lv_datum.ty;
2055 let ptr_ty = ty::mk_imm_rptr(bcx.tcx(), ty::ReStatic, referent_ty);
2058 let llref = lv_datum.to_llref();
2060 // Construct the resulting datum, using what was the "by ref"
2061 // ValueRef of type `referent_ty` to be the "by value" ValueRef
2062 // of type `&referent_ty`.
2063 DatumBlock::new(bcx, Datum::new(llref, ptr_ty, RvalueExpr(Rvalue::new(ByValue))))
2066 fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2068 datum: Datum<'tcx, Expr>,
2070 -> DatumBlock<'blk, 'tcx, Expr> {
2072 let mut datum = datum;
2073 for i in range(0, times) {
2074 let method_call = MethodCall::autoderef(expr.id, i);
2075 datum = unpack_datum!(bcx, deref_once(bcx, expr, datum, method_call));
2077 DatumBlock { bcx: bcx, datum: datum }
2080 fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2082 datum: Datum<'tcx, Expr>,
2083 method_call: MethodCall)
2084 -> DatumBlock<'blk, 'tcx, Expr> {
2085 let ccx = bcx.ccx();
2087 debug!("deref_once(expr={}, datum={}, method_call={})",
2088 expr.repr(bcx.tcx()),
2089 datum.to_string(ccx),
2094 // Check for overloaded deref.
2095 let method_ty = ccx.tcx().method_map.borrow()
2096 .get(&method_call).map(|method| method.ty);
2097 let datum = match method_ty {
2098 Some(method_ty) => {
2099 // Overloaded. Evaluate `trans_overloaded_op`, which will
2100 // invoke the user's deref() method, which basically
2101 // converts from the `Smaht<T>` pointer that we have into
2102 // a `&T` pointer. We can then proceed down the normal
2103 // path (below) to dereference that `&T`.
2104 let datum = match method_call.adjustment {
2105 // Always perform an AutoPtr when applying an overloaded auto-deref
2106 ty::AutoDeref(_) => unpack_datum!(bcx, auto_ref(bcx, datum, expr)),
2110 let ref_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty)).unwrap();
2111 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_deref");
2113 unpack_result!(bcx, trans_overloaded_op(bcx, expr, method_call,
2114 datum, Vec::new(), Some(SaveIn(scratch.val))));
2115 scratch.to_expr_datum()
2118 // Not overloaded. We already have a pointer we know how to deref.
2123 let r = match datum.ty.sty {
2124 ty::ty_uniq(content_ty) => {
2125 if ty::type_is_sized(bcx.tcx(), content_ty) {
2126 deref_owned_pointer(bcx, expr, datum, content_ty)
2128 // A fat pointer and an opened DST value have the same
2129 // representation just different types. Since there is no
2130 // temporary for `*e` here (because it is unsized), we cannot
2131 // emulate the sized object code path for running drop glue and
2132 // free. Instead, we schedule cleanup for `e`, turning it into
2134 let datum = unpack_datum!(
2135 bcx, datum.to_lvalue_datum(bcx, "deref", expr.id));
2137 let datum = Datum::new(datum.val, ty::mk_open(bcx.tcx(), content_ty), LvalueExpr);
2138 DatumBlock::new(bcx, datum)
2142 ty::ty_ptr(ty::mt { ty: content_ty, .. }) |
2143 ty::ty_rptr(_, ty::mt { ty: content_ty, .. }) => {
2144 if ty::type_is_sized(bcx.tcx(), content_ty) {
2145 let ptr = datum.to_llscalarish(bcx);
2147 // Always generate an lvalue datum, even if datum.mode is
2148 // an rvalue. This is because datum.mode is only an
2149 // rvalue for non-owning pointers like &T or *T, in which
2150 // case cleanup *is* scheduled elsewhere, by the true
2151 // owner (or, in the case of *T, by the user).
2152 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr))
2154 // A fat pointer and an opened DST value have the same representation
2155 // just different types.
2156 DatumBlock::new(bcx, Datum::new(datum.val,
2157 ty::mk_open(bcx.tcx(), content_ty),
2163 bcx.tcx().sess.span_bug(
2165 format!("deref invoked on expr of illegal type {}",
2166 datum.ty.repr(bcx.tcx())).as_slice());
2170 debug!("deref_once(expr={}, method_call={}, result={})",
2171 expr.id, method_call, r.datum.to_string(ccx));
2175 /// We microoptimize derefs of owned pointers a bit here. Basically, the idea is to make the
2176 /// deref of an rvalue result in an rvalue. This helps to avoid intermediate stack slots in the
2177 /// resulting LLVM. The idea here is that, if the `Box<T>` pointer is an rvalue, then we can
2178 /// schedule a *shallow* free of the `Box<T>` pointer, and then return a ByRef rvalue into the
2179 /// pointer. Because the free is shallow, it is legit to return an rvalue, because we know that
2180 /// the contents are not yet scheduled to be freed. The language rules ensure that the contents
2181 /// will be used (or moved) before the free occurs.
2182 fn deref_owned_pointer<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2184 datum: Datum<'tcx, Expr>,
2185 content_ty: Ty<'tcx>)
2186 -> DatumBlock<'blk, 'tcx, Expr> {
2188 RvalueExpr(Rvalue { mode: ByRef }) => {
2189 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2190 let ptr = Load(bcx, datum.val);
2191 if !type_is_zero_size(bcx.ccx(), content_ty) {
2192 bcx.fcx.schedule_free_value(scope, ptr, cleanup::HeapExchange, content_ty);
2195 RvalueExpr(Rvalue { mode: ByValue }) => {
2196 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2197 if !type_is_zero_size(bcx.ccx(), content_ty) {
2198 bcx.fcx.schedule_free_value(scope, datum.val, cleanup::HeapExchange,
2205 // If we had an rvalue in, we produce an rvalue out.
2206 let (llptr, kind) = match datum.kind {
2208 (Load(bcx, datum.val), LvalueExpr)
2210 RvalueExpr(Rvalue { mode: ByRef }) => {
2211 (Load(bcx, datum.val), RvalueExpr(Rvalue::new(ByRef)))
2213 RvalueExpr(Rvalue { mode: ByValue }) => {
2214 (datum.val, RvalueExpr(Rvalue::new(ByRef)))
2218 let datum = Datum { ty: content_ty, val: llptr, kind: kind };
2219 DatumBlock { bcx: bcx, datum: datum }