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 // FIXME(#19596) unbox `mk_ty`
299 fn unsized_info<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
300 kind: &ty::UnsizeKind<'tcx>,
302 unadjusted_ty: Ty<'tcx>,
303 mk_ty: |Ty<'tcx>| -> Ty<'tcx>) -> ValueRef {
304 debug!("unsized_info(kind={}, id={}, unadjusted_ty={})",
305 kind, id, unadjusted_ty.repr(bcx.tcx()));
307 &ty::UnsizeLength(len) => C_uint(bcx.ccx(), len),
308 &ty::UnsizeStruct(box ref k, tp_index) => match unadjusted_ty.sty {
309 ty::ty_struct(_, ref substs) => {
310 let ty_substs = substs.types.get_slice(subst::TypeSpace);
311 // The dtor for a field treats it like a value, so mk_ty
312 // should just be the identity function.
313 unsized_info(bcx, k, id, ty_substs[tp_index], |t| t)
315 _ => bcx.sess().bug(format!("UnsizeStruct with bad sty: {}",
316 bcx.ty_to_string(unadjusted_ty)).as_slice())
318 &ty::UnsizeVtable(ty::TyTrait { ref principal, .. }, _) => {
319 let substs = principal.substs.with_self_ty(unadjusted_ty).erase_regions();
321 Rc::new(ty::TraitRef { def_id: principal.def_id,
323 let trait_ref = trait_ref.subst(bcx.tcx(), bcx.fcx.param_substs);
324 let box_ty = mk_ty(unadjusted_ty);
326 meth::get_vtable(bcx, box_ty, trait_ref),
327 Type::vtable_ptr(bcx.ccx()))
332 fn unsize_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
334 datum: Datum<'tcx, Expr>,
335 k: &ty::UnsizeKind<'tcx>)
336 -> DatumBlock<'blk, 'tcx, Expr> {
338 let datum_ty = datum.ty;
339 let unsized_ty = ty::unsize_ty(tcx, datum_ty, k, expr.span);
340 debug!("unsized_ty={}", unsized_ty.repr(bcx.tcx()));
341 let dest_ty = ty::mk_open(tcx, unsized_ty);
342 debug!("dest_ty={}", unsized_ty.repr(bcx.tcx()));
343 // Closures for extracting and manipulating the data and payload parts of
345 let info = |: bcx, _val| unsized_info(bcx,
353 mutbl: ast::MutImmutable
356 ty::UnsizeStruct(..) =>
357 into_fat_ptr(bcx, expr, datum, dest_ty, |bcx, val| {
358 PointerCast(bcx, val, type_of::type_of(bcx.ccx(), unsized_ty).ptr_to())
360 ty::UnsizeLength(..) =>
361 into_fat_ptr(bcx, expr, datum, dest_ty, |bcx, val| {
362 GEPi(bcx, val, &[0u, 0u])
364 ty::UnsizeVtable(..) =>
365 into_fat_ptr(bcx, expr, datum, dest_ty, |_bcx, val| {
366 PointerCast(bcx, val, Type::i8p(bcx.ccx()))
371 fn ref_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
373 datum: Datum<'tcx, Expr>)
374 -> DatumBlock<'blk, 'tcx, Expr> {
376 let dest_ty = ty::close_type(tcx, datum.ty);
377 let base = |: bcx, val| Load(bcx, get_dataptr(bcx, val));
378 let len = |: bcx, val| Load(bcx, get_len(bcx, val));
379 into_fat_ptr(bcx, expr, datum, dest_ty, base, len)
382 fn into_fat_ptr<'blk, 'tcx, F, G>(bcx: Block<'blk, 'tcx>,
384 datum: Datum<'tcx, Expr>,
388 -> DatumBlock<'blk, 'tcx, Expr> where
389 F: FnOnce(Block<'blk, 'tcx>, ValueRef) -> ValueRef,
390 G: FnOnce(Block<'blk, 'tcx>, ValueRef) -> ValueRef,
395 let lval = unpack_datum!(bcx,
396 datum.to_lvalue_datum(bcx, "into_fat_ptr", expr.id));
397 let base = base(bcx, lval.val);
398 let info = info(bcx, lval.val);
400 let scratch = rvalue_scratch_datum(bcx, dest_ty, "__fat_ptr");
401 Store(bcx, base, get_dataptr(bcx, scratch.val));
402 Store(bcx, info, get_len(bcx, scratch.val));
404 DatumBlock::new(bcx, scratch.to_expr_datum())
407 fn unsize_unique_vec<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
409 datum: Datum<'tcx, Expr>,
411 -> DatumBlock<'blk, 'tcx, Expr> {
415 let datum_ty = datum.ty;
417 let lval = unpack_datum!(bcx,
418 datum.to_lvalue_datum(bcx, "unsize_unique_vec", expr.id));
420 let ll_len = C_uint(bcx.ccx(), len);
421 let unit_ty = ty::sequence_element_type(tcx, ty::type_content(datum_ty));
422 let vec_ty = ty::mk_uniq(tcx, ty::mk_vec(tcx, unit_ty, None));
423 let scratch = rvalue_scratch_datum(bcx, vec_ty, "__unsize_unique");
425 let base = get_dataptr(bcx, scratch.val);
426 let base = PointerCast(bcx,
428 type_of::type_of(bcx.ccx(), datum_ty).ptr_to());
429 bcx = lval.store_to(bcx, base);
431 Store(bcx, ll_len, get_len(bcx, scratch.val));
432 DatumBlock::new(bcx, scratch.to_expr_datum())
435 fn unsize_unique_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
437 datum: Datum<'tcx, Expr>,
438 k: &ty::UnsizeKind<'tcx>)
439 -> DatumBlock<'blk, 'tcx, Expr> {
443 let datum_ty = datum.ty;
444 let unboxed_ty = match datum_ty.sty {
446 _ => bcx.sess().bug(format!("Expected ty_uniq, found {}",
447 bcx.ty_to_string(datum_ty)).as_slice())
449 let result_ty = ty::mk_uniq(tcx, ty::unsize_ty(tcx, unboxed_ty, k, expr.span));
451 let lval = unpack_datum!(bcx,
452 datum.to_lvalue_datum(bcx, "unsize_unique_expr", expr.id));
454 let scratch = rvalue_scratch_datum(bcx, result_ty, "__uniq_fat_ptr");
455 let llbox_ty = type_of::type_of(bcx.ccx(), datum_ty);
456 let base = PointerCast(bcx, get_dataptr(bcx, scratch.val), llbox_ty.ptr_to());
457 bcx = lval.store_to(bcx, base);
459 let info = unsized_info(bcx, k, expr.id, unboxed_ty, |t| ty::mk_uniq(tcx, t));
460 Store(bcx, info, get_len(bcx, scratch.val));
462 let scratch = unpack_datum!(bcx,
463 scratch.to_expr_datum().to_lvalue_datum(bcx,
464 "fresh_uniq_fat_ptr",
467 DatumBlock::new(bcx, scratch.to_expr_datum())
470 fn add_env<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
472 datum: Datum<'tcx, Expr>)
473 -> DatumBlock<'blk, 'tcx, Expr> {
474 // This is not the most efficient thing possible; since closures
475 // are two words it'd be better if this were compiled in
476 // 'dest' mode, but I can't find a nice way to structure the
477 // code and keep it DRY that accommodates that use case at the
480 let closure_ty = expr_ty_adjusted(bcx, expr);
481 let fn_ptr = datum.to_llscalarish(bcx);
482 let def = ty::resolve_expr(bcx.tcx(), expr);
483 closure::make_closure_from_bare_fn(bcx, closure_ty, def, fn_ptr)
487 /// Translates an expression in "lvalue" mode -- meaning that it returns a reference to the memory
488 /// that the expr represents.
490 /// If this expression is an rvalue, this implies introducing a temporary. In other words,
491 /// something like `x().f` is translated into roughly the equivalent of
493 /// { tmp = x(); tmp.f }
494 pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
497 -> DatumBlock<'blk, 'tcx, Lvalue> {
499 let datum = unpack_datum!(bcx, trans(bcx, expr));
500 return datum.to_lvalue_datum(bcx, name, expr.id);
503 /// A version of `trans` that ignores adjustments. You almost certainly do not want to call this
505 fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
507 -> DatumBlock<'blk, 'tcx, Expr> {
510 debug!("trans_unadjusted(expr={})", bcx.expr_to_string(expr));
511 let _indenter = indenter();
513 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
515 return match ty::expr_kind(bcx.tcx(), expr) {
516 ty::LvalueExpr | ty::RvalueDatumExpr => {
517 let datum = unpack_datum!(bcx, {
518 trans_datum_unadjusted(bcx, expr)
521 DatumBlock {bcx: bcx, datum: datum}
524 ty::RvalueStmtExpr => {
525 bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
526 nil(bcx, expr_ty(bcx, expr))
529 ty::RvalueDpsExpr => {
530 let ty = expr_ty(bcx, expr);
531 if type_is_zero_size(bcx.ccx(), ty) {
532 bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
535 let scratch = rvalue_scratch_datum(bcx, ty, "");
536 bcx = trans_rvalue_dps_unadjusted(
537 bcx, expr, SaveIn(scratch.val));
539 // Note: this is not obviously a good idea. It causes
540 // immediate values to be loaded immediately after a
541 // return from a call or other similar expression,
542 // which in turn leads to alloca's having shorter
543 // lifetimes and hence larger stack frames. However,
544 // in turn it can lead to more register pressure.
545 // Still, in practice it seems to increase
546 // performance, since we have fewer problems with
548 let scratch = unpack_datum!(
549 bcx, scratch.to_appropriate_datum(bcx));
551 DatumBlock::new(bcx, scratch.to_expr_datum())
556 fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: Ty<'tcx>)
557 -> DatumBlock<'blk, 'tcx, Expr> {
558 let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
559 let datum = immediate_rvalue(llval, ty);
560 DatumBlock::new(bcx, datum.to_expr_datum())
564 fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
566 -> DatumBlock<'blk, 'tcx, Expr> {
569 let _icx = push_ctxt("trans_datum_unadjusted");
572 ast::ExprParen(ref e) => {
575 ast::ExprPath(_) => {
576 trans_def(bcx, expr, bcx.def(expr.id))
578 ast::ExprField(ref base, ident) => {
579 trans_rec_field(bcx, &**base, ident.node)
581 ast::ExprTupField(ref base, idx) => {
582 trans_rec_tup_field(bcx, &**base, idx.node)
584 ast::ExprIndex(ref base, ref idx) => {
585 trans_index(bcx, expr, &**base, &**idx, MethodCall::expr(expr.id))
587 ast::ExprSlice(ref base, ref start, ref end, _) => {
588 let _icx = push_ctxt("trans_slice");
591 let method_call = MethodCall::expr(expr.id);
592 let method_ty = ccx.tcx()
596 .map(|method| method.ty);
597 let base_datum = unpack_datum!(bcx, trans(bcx, &**base));
599 let mut args = vec![];
600 start.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
601 end.as_ref().map(|e| args.push((unpack_datum!(bcx, trans(bcx, &**e)), e.id)));
603 let result_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty.unwrap())).unwrap();
604 let scratch = rvalue_scratch_datum(bcx, result_ty, "trans_slice");
607 trans_overloaded_op(bcx,
612 Some(SaveIn(scratch.val)),
614 DatumBlock::new(bcx, scratch.to_expr_datum())
616 ast::ExprBox(_, ref contents) => {
617 // Special case for `Box<T>`
618 let box_ty = expr_ty(bcx, expr);
619 let contents_ty = expr_ty(bcx, &**contents);
622 trans_uniq_expr(bcx, box_ty, &**contents, contents_ty)
624 _ => bcx.sess().span_bug(expr.span,
625 "expected unique box")
629 ast::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &**lit),
630 ast::ExprBinary(op, ref lhs, ref rhs) => {
631 trans_binary(bcx, expr, op, &**lhs, &**rhs)
633 ast::ExprUnary(op, ref x) => {
634 trans_unary(bcx, expr, op, &**x)
636 ast::ExprAddrOf(_, ref x) => {
638 ast::ExprRepeat(..) | ast::ExprVec(..) => {
639 // Special case for slices.
640 let cleanup_debug_loc =
641 debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
645 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
646 let datum = unpack_datum!(
647 bcx, tvec::trans_slice_vec(bcx, expr, &**x));
648 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
649 DatumBlock::new(bcx, datum)
652 trans_addr_of(bcx, expr, &**x)
656 ast::ExprCast(ref val, _) => {
657 // Datum output mode means this is a scalar cast:
658 trans_imm_cast(bcx, &**val, expr.id)
661 bcx.tcx().sess.span_bug(
663 format!("trans_rvalue_datum_unadjusted reached \
664 fall-through case: {}",
665 expr.node).as_slice());
670 fn trans_field<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
673 -> DatumBlock<'blk, 'tcx, Expr> where
674 F: FnOnce(&'blk ty::ctxt<'tcx>, &[ty::field<'tcx>]) -> uint,
677 let _icx = push_ctxt("trans_rec_field");
679 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
680 let bare_ty = ty::unopen_type(base_datum.ty);
681 let repr = adt::represent_type(bcx.ccx(), bare_ty);
682 with_field_tys(bcx.tcx(), bare_ty, None, move |discr, field_tys| {
683 let ix = get_idx(bcx.tcx(), field_tys);
684 let d = base_datum.get_element(
687 |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, ix));
689 if ty::type_is_sized(bcx.tcx(), d.ty) {
690 DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
692 let scratch = rvalue_scratch_datum(bcx, ty::mk_open(bcx.tcx(), d.ty), "");
693 Store(bcx, d.val, get_dataptr(bcx, scratch.val));
694 let info = Load(bcx, get_len(bcx, base_datum.val));
695 Store(bcx, info, get_len(bcx, scratch.val));
697 DatumBlock::new(bcx, scratch.to_expr_datum())
704 /// Translates `base.field`.
705 fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
708 -> DatumBlock<'blk, 'tcx, Expr> {
709 trans_field(bcx, base, |tcx, field_tys| ty::field_idx_strict(tcx, field.name, field_tys))
712 /// Translates `base.<idx>`.
713 fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
716 -> DatumBlock<'blk, 'tcx, Expr> {
717 trans_field(bcx, base, |_, _| idx)
720 fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
721 index_expr: &ast::Expr,
724 method_call: MethodCall)
725 -> DatumBlock<'blk, 'tcx, Expr> {
726 //! Translates `base[idx]`.
728 let _icx = push_ctxt("trans_index");
732 // Check for overloaded index.
733 let method_ty = ccx.tcx()
737 .map(|method| method.ty);
738 let elt_datum = match method_ty {
740 let base_datum = unpack_datum!(bcx, trans(bcx, base));
742 // Translate index expression.
743 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
745 let ref_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty)).unwrap();
746 let elt_ty = match ty::deref(ref_ty, true) {
748 bcx.tcx().sess.span_bug(index_expr.span,
749 "index method didn't return a \
750 dereferenceable type?!")
752 Some(elt_tm) => elt_tm.ty,
755 // Overloaded. Evaluate `trans_overloaded_op`, which will
756 // invoke the user's index() method, which basically yields
757 // a `&T` pointer. We can then proceed down the normal
758 // path (below) to dereference that `&T`.
759 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_index_elt");
761 trans_overloaded_op(bcx,
765 vec![(ix_datum, idx.id)],
766 Some(SaveIn(scratch.val)),
768 let datum = scratch.to_expr_datum();
769 if ty::type_is_sized(bcx.tcx(), elt_ty) {
770 Datum::new(datum.to_llscalarish(bcx), elt_ty, LvalueExpr)
772 Datum::new(datum.val, ty::mk_open(bcx.tcx(), elt_ty), LvalueExpr)
776 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
780 // Translate index expression and cast to a suitable LLVM integer.
781 // Rust is less strict than LLVM in this regard.
782 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
783 let ix_val = ix_datum.to_llscalarish(bcx);
784 let ix_size = machine::llbitsize_of_real(bcx.ccx(),
786 let int_size = machine::llbitsize_of_real(bcx.ccx(),
789 if ix_size < int_size {
790 if ty::type_is_signed(expr_ty(bcx, idx)) {
791 SExt(bcx, ix_val, ccx.int_type())
792 } else { ZExt(bcx, ix_val, ccx.int_type()) }
793 } else if ix_size > int_size {
794 Trunc(bcx, ix_val, ccx.int_type())
802 ty::sequence_element_type(bcx.tcx(),
804 base::maybe_name_value(bcx.ccx(), vt.llunit_size, "unit_sz");
806 let (base, len) = base_datum.get_vec_base_and_len(bcx);
808 debug!("trans_index: base {}", bcx.val_to_string(base));
809 debug!("trans_index: len {}", bcx.val_to_string(len));
811 let bounds_check = ICmp(bcx, llvm::IntUGE, ix_val, len);
812 let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
813 let expected = Call(bcx,
815 &[bounds_check, C_bool(ccx, false)],
817 bcx = with_cond(bcx, expected, |bcx| {
818 controlflow::trans_fail_bounds_check(bcx,
823 let elt = InBoundsGEP(bcx, base, &[ix_val]);
824 let elt = PointerCast(bcx, elt, vt.llunit_ty.ptr_to());
825 Datum::new(elt, vt.unit_ty, LvalueExpr)
829 DatumBlock::new(bcx, elt_datum)
832 fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
833 ref_expr: &ast::Expr,
835 -> DatumBlock<'blk, 'tcx, Expr> {
836 //! Translates a reference to a path.
838 let _icx = push_ctxt("trans_def_lvalue");
840 def::DefFn(..) | def::DefStaticMethod(..) | def::DefMethod(..) |
841 def::DefStruct(_) | def::DefVariant(..) => {
842 trans_def_fn_unadjusted(bcx, ref_expr, def)
844 def::DefStatic(did, _) => {
845 // There are two things that may happen here:
846 // 1) If the static item is defined in this crate, it will be
847 // translated using `get_item_val`, and we return a pointer to
849 // 2) If the static item is defined in another crate then we add
850 // (or reuse) a declaration of an external global, and return a
852 let const_ty = expr_ty(bcx, ref_expr);
854 fn get_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, did: ast::DefId,
855 const_ty: Ty<'tcx>) -> ValueRef {
856 // For external constants, we don't inline.
857 if did.krate == ast::LOCAL_CRATE {
860 // The LLVM global has the type of its initializer,
861 // which may not be equal to the enum's type for
863 let val = base::get_item_val(bcx.ccx(), did.node);
864 let pty = type_of::type_of(bcx.ccx(), const_ty).ptr_to();
865 PointerCast(bcx, val, pty)
868 base::get_extern_const(bcx.ccx(), did, const_ty)
871 let val = get_val(bcx, did, const_ty);
872 DatumBlock::new(bcx, Datum::new(val, const_ty, LvalueExpr))
874 def::DefConst(did) => {
875 // First, inline any external constants into the local crate so we
876 // can be sure to get the LLVM value corresponding to it.
877 let did = inline::maybe_instantiate_inline(bcx.ccx(), did);
878 if did.krate != ast::LOCAL_CRATE {
879 bcx.tcx().sess.span_bug(ref_expr.span,
880 "cross crate constant could not \
883 let val = base::get_item_val(bcx.ccx(), did.node);
885 // Next, we need to crate a ByRef rvalue datum to return. We can't
886 // use the normal .to_ref_datum() function because the type of
887 // `val` is not actually the same as `const_ty`.
889 // To get around this, we make a custom alloca slot with the
890 // appropriate type (const_ty), and then we cast it to a pointer of
891 // typeof(val), store the value, and then hand this slot over to
892 // the datum infrastructure.
893 let const_ty = expr_ty(bcx, ref_expr);
894 let llty = type_of::type_of(bcx.ccx(), const_ty);
895 let slot = alloca(bcx, llty, "const");
896 let pty = Type::from_ref(unsafe { llvm::LLVMTypeOf(val) }).ptr_to();
897 Store(bcx, val, PointerCast(bcx, slot, pty));
899 let datum = Datum::new(slot, const_ty, Rvalue::new(ByRef));
900 DatumBlock::new(bcx, datum.to_expr_datum())
903 DatumBlock::new(bcx, trans_local_var(bcx, def).to_expr_datum())
908 fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
910 -> Block<'blk, 'tcx> {
912 let _icx = push_ctxt("trans_rvalue_stmt");
914 if bcx.unreachable.get() {
918 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
921 ast::ExprParen(ref e) => {
922 trans_into(bcx, &**e, Ignore)
924 ast::ExprBreak(label_opt) => {
925 controlflow::trans_break(bcx, expr.id, label_opt)
927 ast::ExprAgain(label_opt) => {
928 controlflow::trans_cont(bcx, expr.id, label_opt)
930 ast::ExprRet(ref ex) => {
931 // Check to see if the return expression itself is reachable.
932 // This can occur when the inner expression contains a return
933 let reachable = if let Some(ref cfg) = bcx.fcx.cfg {
934 cfg.node_is_reachable(expr.id)
940 controlflow::trans_ret(bcx, ex.as_ref().map(|e| &**e))
942 // If it's not reachable, just translate the inner expression
943 // directly. This avoids having to manage a return slot when
944 // it won't actually be used anyway.
945 if let &Some(ref x) = ex {
946 bcx = trans_into(bcx, &**x, Ignore);
948 // Mark the end of the block as unreachable. Once we get to
949 // a return expression, there's no more we should be doing
955 ast::ExprWhile(ref cond, ref body, _) => {
956 controlflow::trans_while(bcx, expr.id, &**cond, &**body)
958 ast::ExprForLoop(ref pat, ref head, ref body, _) => {
959 controlflow::trans_for(bcx,
965 ast::ExprLoop(ref body, _) => {
966 controlflow::trans_loop(bcx, expr.id, &**body)
968 ast::ExprAssign(ref dst, ref src) => {
969 let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
970 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &**dst, "assign"));
972 if ty::type_needs_drop(bcx.tcx(), dst_datum.ty) {
973 // If there are destructors involved, make sure we
974 // are copying from an rvalue, since that cannot possible
975 // alias an lvalue. We are concerned about code like:
983 // where e.g. a : Option<Foo> and a.b :
984 // Option<Foo>. In that case, freeing `a` before the
985 // assignment may also free `a.b`!
987 // We could avoid this intermediary with some analysis
988 // to determine whether `dst` may possibly own `src`.
989 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
990 let src_datum = unpack_datum!(
991 bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
992 bcx = glue::drop_ty(bcx,
995 Some(NodeInfo { id: expr.id, span: expr.span }));
996 src_datum.store_to(bcx, dst_datum.val)
998 src_datum.store_to(bcx, dst_datum.val)
1001 ast::ExprAssignOp(op, ref dst, ref src) => {
1002 trans_assign_op(bcx, expr, op, &**dst, &**src)
1004 ast::ExprInlineAsm(ref a) => {
1005 asm::trans_inline_asm(bcx, a)
1008 bcx.tcx().sess.span_bug(
1010 format!("trans_rvalue_stmt_unadjusted reached \
1011 fall-through case: {}",
1012 expr.node).as_slice());
1017 fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1020 -> Block<'blk, 'tcx> {
1021 let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
1023 let tcx = bcx.tcx();
1025 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
1028 ast::ExprParen(ref e) => {
1029 trans_into(bcx, &**e, dest)
1031 ast::ExprPath(_) => {
1032 trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
1034 ast::ExprIf(ref cond, ref thn, ref els) => {
1035 controlflow::trans_if(bcx, expr.id, &**cond, &**thn, els.as_ref().map(|e| &**e), dest)
1037 ast::ExprMatch(ref discr, ref arms, _) => {
1038 _match::trans_match(bcx, expr, &**discr, arms.as_slice(), dest)
1040 ast::ExprBlock(ref blk) => {
1041 controlflow::trans_block(bcx, &**blk, dest)
1043 ast::ExprStruct(_, ref fields, ref base) => {
1046 base.as_ref().map(|e| &**e),
1051 ast::ExprTup(ref args) => {
1052 let numbered_fields: Vec<(uint, &ast::Expr)> =
1053 args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
1057 numbered_fields.as_slice(),
1060 Some(NodeInfo { id: expr.id, span: expr.span }))
1062 ast::ExprLit(ref lit) => {
1064 ast::LitStr(ref s, _) => {
1065 tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
1070 .span_bug(expr.span,
1071 "trans_rvalue_dps_unadjusted shouldn't be \
1072 translating this type of literal")
1076 ast::ExprVec(..) | ast::ExprRepeat(..) => {
1077 tvec::trans_fixed_vstore(bcx, expr, dest)
1079 ast::ExprClosure(_, _, ref decl, ref body) => {
1080 // Check the side-table to see whether this is an unboxed
1081 // closure or an older, legacy style closure. Store this
1082 // into a variable to ensure the the RefCell-lock is
1083 // released before we recurse.
1084 let is_unboxed_closure =
1085 bcx.tcx().unboxed_closures.borrow().contains_key(&ast_util::local_def(expr.id));
1086 if is_unboxed_closure {
1087 closure::trans_unboxed_closure(bcx, &**decl, &**body, expr.id, dest)
1089 let expr_ty = expr_ty(bcx, expr);
1090 let store = ty::ty_closure_store(expr_ty);
1091 debug!("translating block function {} with type {}",
1092 expr_to_string(expr), expr_ty.repr(tcx));
1093 closure::trans_expr_fn(bcx, store, &**decl, &**body, expr.id, dest)
1096 ast::ExprCall(ref f, ref args) => {
1097 if bcx.tcx().is_method_call(expr.id) {
1098 trans_overloaded_call(bcx,
1104 callee::trans_call(bcx,
1107 callee::ArgExprs(args.as_slice()),
1111 ast::ExprMethodCall(_, _, ref args) => {
1112 callee::trans_method_call(bcx,
1115 callee::ArgExprs(args.as_slice()),
1118 ast::ExprBinary(op, ref lhs, ref rhs) => {
1119 // if not overloaded, would be RvalueDatumExpr
1120 let lhs = unpack_datum!(bcx, trans(bcx, &**lhs));
1121 let rhs_datum = unpack_datum!(bcx, trans(bcx, &**rhs));
1122 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), lhs,
1123 vec![(rhs_datum, rhs.id)], Some(dest),
1124 !ast_util::is_by_value_binop(op)).bcx
1126 ast::ExprUnary(_, ref subexpr) => {
1127 // if not overloaded, would be RvalueDatumExpr
1128 let arg = unpack_datum!(bcx, trans(bcx, &**subexpr));
1129 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id),
1130 arg, Vec::new(), Some(dest), true).bcx
1132 ast::ExprIndex(ref base, ref idx) => {
1133 // if not overloaded, would be RvalueDatumExpr
1134 let base = unpack_datum!(bcx, trans(bcx, &**base));
1135 let idx_datum = unpack_datum!(bcx, trans(bcx, &**idx));
1136 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), base,
1137 vec![(idx_datum, idx.id)], Some(dest), true).bcx
1139 ast::ExprCast(ref val, _) => {
1140 // DPS output mode means this is a trait cast:
1141 if ty::type_is_trait(node_id_type(bcx, expr.id)) {
1143 bcx.tcx().object_cast_map.borrow()
1145 .map(|t| (*t).clone())
1147 let trait_ref = trait_ref.subst(bcx.tcx(), bcx.fcx.param_substs);
1148 let datum = unpack_datum!(bcx, trans(bcx, &**val));
1149 meth::trans_trait_cast(bcx, datum, expr.id,
1152 bcx.tcx().sess.span_bug(expr.span,
1153 "expr_cast of non-trait");
1156 ast::ExprAssignOp(op, ref dst, ref src) => {
1157 trans_assign_op(bcx, expr, op, &**dst, &**src)
1160 bcx.tcx().sess.span_bug(
1162 format!("trans_rvalue_dps_unadjusted reached fall-through \
1164 expr.node).as_slice());
1169 fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1170 ref_expr: &ast::Expr,
1173 -> Block<'blk, 'tcx> {
1174 let _icx = push_ctxt("trans_def_dps_unadjusted");
1176 let lldest = match dest {
1177 SaveIn(lldest) => lldest,
1178 Ignore => { return bcx; }
1182 def::DefVariant(tid, vid, _) => {
1183 let variant_info = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
1184 if variant_info.args.len() > 0u {
1186 let llfn = callee::trans_fn_ref(bcx, vid, ExprId(ref_expr.id));
1187 Store(bcx, llfn, lldest);
1191 let ty = expr_ty(bcx, ref_expr);
1192 let repr = adt::represent_type(bcx.ccx(), ty);
1193 adt::trans_set_discr(bcx, &*repr, lldest,
1194 variant_info.disr_val);
1198 def::DefStruct(_) => {
1199 let ty = expr_ty(bcx, ref_expr);
1201 ty::ty_struct(did, _) if ty::has_dtor(bcx.tcx(), did) => {
1202 let repr = adt::represent_type(bcx.ccx(), ty);
1203 adt::trans_set_discr(bcx, &*repr, lldest, 0);
1210 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1211 "Non-DPS def {} referened by {}",
1212 def, bcx.node_id_to_string(ref_expr.id)).as_slice());
1217 fn trans_def_fn_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1218 ref_expr: &ast::Expr,
1220 -> DatumBlock<'blk, 'tcx, Expr> {
1221 let _icx = push_ctxt("trans_def_datum_unadjusted");
1223 let llfn = match def {
1224 def::DefFn(did, _) |
1225 def::DefStruct(did) | def::DefVariant(_, did, _) |
1226 def::DefStaticMethod(did, def::FromImpl(_)) |
1227 def::DefMethod(did, _, def::FromImpl(_)) => {
1228 callee::trans_fn_ref(bcx, did, ExprId(ref_expr.id))
1230 def::DefStaticMethod(impl_did, def::FromTrait(trait_did)) |
1231 def::DefMethod(impl_did, _, def::FromTrait(trait_did)) => {
1232 meth::trans_static_method_callee(bcx, impl_did,
1233 trait_did, ref_expr.id)
1236 bcx.tcx().sess.span_bug(ref_expr.span, format!(
1237 "trans_def_fn_unadjusted invoked on: {} for {}",
1239 ref_expr.repr(bcx.tcx())).as_slice());
1243 let fn_ty = expr_ty(bcx, ref_expr);
1244 DatumBlock::new(bcx, Datum::new(llfn, fn_ty, RvalueExpr(Rvalue::new(ByValue))))
1247 /// Translates a reference to a local variable or argument. This always results in an lvalue datum.
1248 pub fn trans_local_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1250 -> Datum<'tcx, Lvalue> {
1251 let _icx = push_ctxt("trans_local_var");
1254 def::DefUpvar(nid, _, _) => {
1255 // Can't move upvars, so this is never a ZeroMemLastUse.
1256 let local_ty = node_id_type(bcx, nid);
1257 match bcx.fcx.llupvars.borrow().get(&nid) {
1258 Some(&val) => Datum::new(val, local_ty, Lvalue),
1260 bcx.sess().bug(format!(
1261 "trans_local_var: no llval for upvar {} found",
1266 def::DefLocal(nid) => {
1267 let datum = match bcx.fcx.lllocals.borrow().get(&nid) {
1270 bcx.sess().bug(format!(
1271 "trans_local_var: no datum for local/arg {} found",
1275 debug!("take_local(nid={}, v={}, ty={})",
1276 nid, bcx.val_to_string(datum.val), bcx.ty_to_string(datum.ty));
1280 bcx.sess().unimpl(format!(
1281 "unsupported def type in trans_local_var: {}",
1287 /// Helper for enumerating the field types of structs, enums, or records. The optional node ID here
1288 /// is the node ID of the path identifying the enum variant in use. If none, this cannot possibly
1289 /// an enum variant (so, if it is and `node_id_opt` is none, this function panics).
1290 pub fn with_field_tys<'tcx, R, F>(tcx: &ty::ctxt<'tcx>,
1292 node_id_opt: Option<ast::NodeId>,
1295 F: FnOnce(ty::Disr, &[ty::field<'tcx>]) -> R,
1298 ty::ty_struct(did, ref substs) => {
1299 op(0, struct_fields(tcx, did, substs).as_slice())
1302 ty::ty_tup(ref v) => {
1303 op(0, tup_fields(v.as_slice()).as_slice())
1306 ty::ty_enum(_, ref substs) => {
1307 // We want the *variant* ID here, not the enum ID.
1310 tcx.sess.bug(format!(
1311 "cannot get field types from the enum type {} \
1313 ty.repr(tcx)).as_slice());
1316 let def = tcx.def_map.borrow()[node_id].clone();
1318 def::DefVariant(enum_id, variant_id, _) => {
1319 let variant_info = ty::enum_variant_with_id(
1320 tcx, enum_id, variant_id);
1321 op(variant_info.disr_val,
1327 tcx.sess.bug("resolve didn't map this expr to a \
1336 tcx.sess.bug(format!(
1337 "cannot get field types from the type {}",
1338 ty.repr(tcx)).as_slice());
1343 fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1344 fields: &[ast::Field],
1345 base: Option<&ast::Expr>,
1346 expr_span: codemap::Span,
1347 expr_id: ast::NodeId,
1348 dest: Dest) -> Block<'blk, 'tcx> {
1349 let _icx = push_ctxt("trans_rec");
1351 let ty = node_id_type(bcx, expr_id);
1352 let tcx = bcx.tcx();
1353 with_field_tys(tcx, ty, Some(expr_id), |discr, field_tys| {
1354 let mut need_base = Vec::from_elem(field_tys.len(), true);
1356 let numbered_fields = fields.iter().map(|field| {
1358 field_tys.iter().position(|field_ty|
1359 field_ty.name == field.ident.node.name);
1362 need_base[i] = false;
1366 tcx.sess.span_bug(field.span,
1367 "Couldn't find field in struct type")
1370 }).collect::<Vec<_>>();
1371 let optbase = match base {
1372 Some(base_expr) => {
1373 let mut leftovers = Vec::new();
1374 for (i, b) in need_base.iter().enumerate() {
1376 leftovers.push((i, field_tys[i].mt.ty))
1379 Some(StructBaseInfo {expr: base_expr,
1380 fields: leftovers })
1383 if need_base.iter().any(|b| *b) {
1384 tcx.sess.span_bug(expr_span, "missing fields and no base expr")
1393 numbered_fields.as_slice(),
1396 Some(NodeInfo { id: expr_id, span: expr_span }))
1400 /// Information that `trans_adt` needs in order to fill in the fields
1401 /// of a struct copied from a base struct (e.g., from an expression
1402 /// like `Foo { a: b, ..base }`.
1404 /// Note that `fields` may be empty; the base expression must always be
1405 /// evaluated for side-effects.
1406 pub struct StructBaseInfo<'a, 'tcx> {
1407 /// The base expression; will be evaluated after all explicit fields.
1408 expr: &'a ast::Expr,
1409 /// The indices of fields to copy paired with their types.
1410 fields: Vec<(uint, Ty<'tcx>)>
1413 /// Constructs an ADT instance:
1415 /// - `fields` should be a list of field indices paired with the
1416 /// expression to store into that field. The initializers will be
1417 /// evaluated in the order specified by `fields`.
1419 /// - `optbase` contains information on the base struct (if any) from
1420 /// which remaining fields are copied; see comments on `StructBaseInfo`.
1421 pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1424 fields: &[(uint, &ast::Expr)],
1425 optbase: Option<StructBaseInfo<'a, 'tcx>>,
1427 source_location: Option<NodeInfo>)
1428 -> Block<'blk, 'tcx> {
1429 let _icx = push_ctxt("trans_adt");
1431 let repr = adt::represent_type(bcx.ccx(), ty);
1433 match source_location {
1434 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1440 // If we don't care about the result, just make a
1441 // temporary stack slot
1442 let addr = match dest {
1444 Ignore => alloc_ty(bcx, ty, "temp"),
1447 // This scope holds intermediates that must be cleaned should
1448 // panic occur before the ADT as a whole is ready.
1449 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1451 // First we trans the base, if we have one, to the dest
1452 for base in optbase.iter() {
1453 assert_eq!(discr, 0);
1455 match ty::expr_kind(bcx.tcx(), &*base.expr) {
1456 ty::RvalueDpsExpr | ty::RvalueDatumExpr if !ty::type_needs_drop(bcx.tcx(), ty) => {
1457 bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
1459 ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr"),
1461 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
1462 for &(i, t) in base.fields.iter() {
1463 let datum = base_datum.get_element(
1464 bcx, t, |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, i));
1465 assert!(ty::type_is_sized(bcx.tcx(), datum.ty));
1466 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1467 bcx = datum.store_to(bcx, dest);
1473 match source_location {
1474 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1480 if ty::type_is_simd(bcx.tcx(), ty) {
1481 // This is the constructor of a SIMD type, such types are
1482 // always primitive machine types and so do not have a
1483 // destructor or require any clean-up.
1484 let llty = type_of::type_of(bcx.ccx(), ty);
1486 // keep a vector as a register, and running through the field
1487 // `insertelement`ing them directly into that register
1488 // (i.e. avoid GEPi and `store`s to an alloca) .
1489 let mut vec_val = C_undef(llty);
1491 for &(i, ref e) in fields.iter() {
1492 let block_datum = trans(bcx, &**e);
1493 bcx = block_datum.bcx;
1494 let position = C_uint(bcx.ccx(), i);
1495 let value = block_datum.datum.to_llscalarish(bcx);
1496 vec_val = InsertElement(bcx, vec_val, value, position);
1498 Store(bcx, vec_val, addr);
1500 // Now, we just overwrite the fields we've explicitly specified
1501 for &(i, ref e) in fields.iter() {
1502 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1503 let e_ty = expr_ty_adjusted(bcx, &**e);
1504 bcx = trans_into(bcx, &**e, SaveIn(dest));
1505 let scope = cleanup::CustomScope(custom_cleanup_scope);
1506 fcx.schedule_lifetime_end(scope, dest);
1507 fcx.schedule_drop_mem(scope, dest, e_ty);
1511 adt::trans_set_discr(bcx, &*repr, addr, discr);
1513 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1515 // If we don't care about the result drop the temporary we made
1519 bcx = glue::drop_ty(bcx, addr, ty, source_location);
1520 base::call_lifetime_end(bcx, addr);
1527 fn trans_immediate_lit<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1530 -> DatumBlock<'blk, 'tcx, Expr> {
1531 // must not be a string constant, that is a RvalueDpsExpr
1532 let _icx = push_ctxt("trans_immediate_lit");
1533 let ty = expr_ty(bcx, expr);
1534 let v = consts::const_lit(bcx.ccx(), expr, lit);
1535 immediate_rvalue_bcx(bcx, v, ty).to_expr_datumblock()
1538 fn trans_unary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1541 sub_expr: &ast::Expr)
1542 -> DatumBlock<'blk, 'tcx, Expr> {
1543 let ccx = bcx.ccx();
1545 let _icx = push_ctxt("trans_unary_datum");
1547 let method_call = MethodCall::expr(expr.id);
1549 // The only overloaded operator that is translated to a datum
1550 // is an overloaded deref, since it is always yields a `&T`.
1551 // Otherwise, we should be in the RvalueDpsExpr path.
1553 op == ast::UnDeref ||
1554 !ccx.tcx().method_map.borrow().contains_key(&method_call));
1556 let un_ty = expr_ty(bcx, expr);
1560 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1561 let llresult = Not(bcx, datum.to_llscalarish(bcx));
1562 immediate_rvalue_bcx(bcx, llresult, un_ty).to_expr_datumblock()
1565 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1566 let val = datum.to_llscalarish(bcx);
1568 if ty::type_is_fp(un_ty) {
1574 immediate_rvalue_bcx(bcx, llneg, un_ty).to_expr_datumblock()
1577 trans_uniq_expr(bcx, un_ty, sub_expr, expr_ty(bcx, sub_expr))
1580 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1581 deref_once(bcx, expr, datum, method_call)
1586 fn trans_uniq_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1588 contents: &ast::Expr,
1589 contents_ty: Ty<'tcx>)
1590 -> DatumBlock<'blk, 'tcx, Expr> {
1591 let _icx = push_ctxt("trans_uniq_expr");
1593 assert!(ty::type_is_sized(bcx.tcx(), contents_ty));
1594 let llty = type_of::type_of(bcx.ccx(), contents_ty);
1595 let size = llsize_of(bcx.ccx(), llty);
1596 let align = C_uint(bcx.ccx(), type_of::align_of(bcx.ccx(), contents_ty));
1597 let llty_ptr = llty.ptr_to();
1598 let Result { bcx, val } = malloc_raw_dyn(bcx, llty_ptr, box_ty, size, align);
1599 // Unique boxes do not allocate for zero-size types. The standard library
1600 // may assume that `free` is never called on the pointer returned for
1601 // `Box<ZeroSizeType>`.
1602 let bcx = if llsize_of_alloc(bcx.ccx(), llty) == 0 {
1603 trans_into(bcx, contents, SaveIn(val))
1605 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1606 fcx.schedule_free_value(cleanup::CustomScope(custom_cleanup_scope),
1607 val, cleanup::HeapExchange, contents_ty);
1608 let bcx = trans_into(bcx, contents, SaveIn(val));
1609 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1612 immediate_rvalue_bcx(bcx, val, box_ty).to_expr_datumblock()
1615 fn trans_addr_of<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1617 subexpr: &ast::Expr)
1618 -> DatumBlock<'blk, 'tcx, Expr> {
1619 let _icx = push_ctxt("trans_addr_of");
1621 let sub_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, subexpr, "addr_of"));
1622 match sub_datum.ty.sty {
1624 // Opened DST value, close to a fat pointer
1625 debug!("Closing fat pointer {}", bcx.ty_to_string(sub_datum.ty));
1627 let scratch = rvalue_scratch_datum(bcx,
1628 ty::close_type(bcx.tcx(), sub_datum.ty),
1630 let base = Load(bcx, get_dataptr(bcx, sub_datum.val));
1631 Store(bcx, base, get_dataptr(bcx, scratch.val));
1633 let len = Load(bcx, get_len(bcx, sub_datum.val));
1634 Store(bcx, len, get_len(bcx, scratch.val));
1636 DatumBlock::new(bcx, scratch.to_expr_datum())
1639 // Sized value, ref to a thin pointer
1640 let ty = expr_ty(bcx, expr);
1641 immediate_rvalue_bcx(bcx, sub_datum.val, ty).to_expr_datumblock()
1646 // Important to get types for both lhs and rhs, because one might be _|_
1647 // and the other not.
1648 fn trans_eager_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1649 binop_expr: &ast::Expr,
1656 -> DatumBlock<'blk, 'tcx, Expr> {
1657 let _icx = push_ctxt("trans_eager_binop");
1659 let tcx = bcx.tcx();
1660 let is_simd = ty::type_is_simd(tcx, lhs_t);
1662 if is_simd { ty::simd_type(tcx, lhs_t) }
1665 let is_float = ty::type_is_fp(intype);
1666 let is_signed = ty::type_is_signed(intype);
1668 let rhs = base::cast_shift_expr_rhs(bcx, op, lhs, rhs);
1671 let val = match op {
1673 if is_float { FAdd(bcx, lhs, rhs) }
1674 else { Add(bcx, lhs, rhs) }
1677 if is_float { FSub(bcx, lhs, rhs) }
1678 else { Sub(bcx, lhs, rhs) }
1681 if is_float { FMul(bcx, lhs, rhs) }
1682 else { Mul(bcx, lhs, rhs) }
1688 // Only zero-check integers; fp /0 is NaN
1689 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1690 op, lhs, rhs, rhs_t);
1702 // Only zero-check integers; fp %0 is NaN
1703 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1704 op, lhs, rhs, rhs_t);
1712 ast::BiBitOr => Or(bcx, lhs, rhs),
1713 ast::BiBitAnd => And(bcx, lhs, rhs),
1714 ast::BiBitXor => Xor(bcx, lhs, rhs),
1715 ast::BiShl => Shl(bcx, lhs, rhs),
1719 } else { LShr(bcx, lhs, rhs) }
1721 ast::BiEq | ast::BiNe | ast::BiLt | ast::BiGe | ast::BiLe | ast::BiGt => {
1722 if ty::type_is_scalar(rhs_t) {
1723 unpack_result!(bcx, base::compare_scalar_types(bcx, lhs, rhs, rhs_t, op))
1725 base::compare_simd_types(bcx, lhs, rhs, intype, ty::simd_size(tcx, lhs_t), op)
1727 bcx.tcx().sess.span_bug(binop_expr.span, "comparison operator unsupported for type")
1731 bcx.tcx().sess.span_bug(binop_expr.span, "unexpected binop");
1735 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1738 // refinement types would obviate the need for this
1739 enum lazy_binop_ty {
1744 fn trans_lazy_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1745 binop_expr: &ast::Expr,
1749 -> DatumBlock<'blk, 'tcx, Expr> {
1750 let _icx = push_ctxt("trans_lazy_binop");
1751 let binop_ty = expr_ty(bcx, binop_expr);
1754 let DatumBlock {bcx: past_lhs, datum: lhs} = trans(bcx, a);
1755 let lhs = lhs.to_llscalarish(past_lhs);
1757 if past_lhs.unreachable.get() {
1758 return immediate_rvalue_bcx(past_lhs, lhs, binop_ty).to_expr_datumblock();
1761 let join = fcx.new_id_block("join", binop_expr.id);
1762 let before_rhs = fcx.new_id_block("before_rhs", b.id);
1765 lazy_and => CondBr(past_lhs, lhs, before_rhs.llbb, join.llbb),
1766 lazy_or => CondBr(past_lhs, lhs, join.llbb, before_rhs.llbb)
1769 let DatumBlock {bcx: past_rhs, datum: rhs} = trans(before_rhs, b);
1770 let rhs = rhs.to_llscalarish(past_rhs);
1772 if past_rhs.unreachable.get() {
1773 return immediate_rvalue_bcx(join, lhs, binop_ty).to_expr_datumblock();
1776 Br(past_rhs, join.llbb);
1777 let phi = Phi(join, Type::i1(bcx.ccx()), &[lhs, rhs],
1778 &[past_lhs.llbb, past_rhs.llbb]);
1780 return immediate_rvalue_bcx(join, phi, binop_ty).to_expr_datumblock();
1783 fn trans_binary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1788 -> DatumBlock<'blk, 'tcx, Expr> {
1789 let _icx = push_ctxt("trans_binary");
1790 let ccx = bcx.ccx();
1792 // if overloaded, would be RvalueDpsExpr
1793 assert!(!ccx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
1797 trans_lazy_binop(bcx, expr, lazy_and, lhs, rhs)
1800 trans_lazy_binop(bcx, expr, lazy_or, lhs, rhs)
1804 let lhs_datum = unpack_datum!(bcx, trans(bcx, lhs));
1805 let rhs_datum = unpack_datum!(bcx, trans(bcx, rhs));
1806 let binop_ty = expr_ty(bcx, expr);
1808 debug!("trans_binary (expr {}): lhs_datum={}",
1810 lhs_datum.to_string(ccx));
1811 let lhs_ty = lhs_datum.ty;
1812 let lhs = lhs_datum.to_llscalarish(bcx);
1814 debug!("trans_binary (expr {}): rhs_datum={}",
1816 rhs_datum.to_string(ccx));
1817 let rhs_ty = rhs_datum.ty;
1818 let rhs = rhs_datum.to_llscalarish(bcx);
1819 trans_eager_binop(bcx, expr, binop_ty, op,
1820 lhs_ty, lhs, rhs_ty, rhs)
1825 fn trans_overloaded_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1827 method_call: MethodCall,
1828 lhs: Datum<'tcx, Expr>,
1829 rhs: Vec<(Datum<'tcx, Expr>, ast::NodeId)>,
1832 -> Result<'blk, 'tcx> {
1833 let method_ty = (*bcx.tcx().method_map.borrow())[method_call].ty;
1834 callee::trans_call_inner(bcx,
1835 Some(expr_info(expr)),
1836 monomorphize_type(bcx, method_ty),
1837 |bcx, arg_cleanup_scope| {
1838 meth::trans_method_callee(bcx,
1843 callee::ArgOverloadedOp(lhs, rhs, autoref),
1847 fn trans_overloaded_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1849 callee: &'a ast::Expr,
1850 args: &'a [P<ast::Expr>],
1852 -> Block<'blk, 'tcx> {
1853 let method_call = MethodCall::expr(expr.id);
1854 let method_type = (*bcx.tcx()
1856 .borrow())[method_call]
1858 let mut all_args = vec!(callee);
1859 all_args.extend(args.iter().map(|e| &**e));
1861 callee::trans_call_inner(bcx,
1862 Some(expr_info(expr)),
1863 monomorphize_type(bcx,
1865 |bcx, arg_cleanup_scope| {
1866 meth::trans_method_callee(
1872 callee::ArgOverloadedCall(all_args),
1877 fn int_cast(bcx: Block,
1883 let _icx = push_ctxt("int_cast");
1885 let srcsz = llvm::LLVMGetIntTypeWidth(llsrctype.to_ref());
1886 let dstsz = llvm::LLVMGetIntTypeWidth(lldsttype.to_ref());
1887 return if dstsz == srcsz {
1888 BitCast(bcx, llsrc, lldsttype)
1889 } else if srcsz > dstsz {
1890 TruncOrBitCast(bcx, llsrc, lldsttype)
1892 SExtOrBitCast(bcx, llsrc, lldsttype)
1894 ZExtOrBitCast(bcx, llsrc, lldsttype)
1899 fn float_cast(bcx: Block,
1904 let _icx = push_ctxt("float_cast");
1905 let srcsz = llsrctype.float_width();
1906 let dstsz = lldsttype.float_width();
1907 return if dstsz > srcsz {
1908 FPExt(bcx, llsrc, lldsttype)
1909 } else if srcsz > dstsz {
1910 FPTrunc(bcx, llsrc, lldsttype)
1914 #[deriving(PartialEq, Show)]
1915 pub enum cast_kind {
1923 impl Copy for cast_kind {}
1925 pub fn cast_type_kind<'tcx>(tcx: &ty::ctxt<'tcx>, t: Ty<'tcx>) -> cast_kind {
1927 ty::ty_char => cast_integral,
1928 ty::ty_float(..) => cast_float,
1929 ty::ty_rptr(_, mt) | ty::ty_ptr(mt) => {
1930 if ty::type_is_sized(tcx, mt.ty) {
1936 ty::ty_bare_fn(..) => cast_pointer,
1937 ty::ty_int(..) => cast_integral,
1938 ty::ty_uint(..) => cast_integral,
1939 ty::ty_bool => cast_integral,
1940 ty::ty_enum(..) => cast_enum,
1945 fn cast_is_noop<'tcx>(t_in: Ty<'tcx>, t_out: Ty<'tcx>) -> bool {
1946 match (ty::deref(t_in, true), ty::deref(t_out, true)) {
1947 (Some(ty::mt{ ty: t_in, .. }), Some(ty::mt{ ty: t_out, .. })) => {
1954 fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1957 -> DatumBlock<'blk, 'tcx, Expr> {
1958 let _icx = push_ctxt("trans_cast");
1960 let ccx = bcx.ccx();
1962 let t_in = expr_ty(bcx, expr);
1963 let t_out = node_id_type(bcx, id);
1964 let k_in = cast_type_kind(bcx.tcx(), t_in);
1965 let k_out = cast_type_kind(bcx.tcx(), t_out);
1966 let s_in = k_in == cast_integral && ty::type_is_signed(t_in);
1967 let ll_t_in = type_of::arg_type_of(ccx, t_in);
1968 let ll_t_out = type_of::arg_type_of(ccx, t_out);
1970 // Convert the value to be cast into a ValueRef, either by-ref or
1971 // by-value as appropriate given its type:
1972 let mut datum = unpack_datum!(bcx, trans(bcx, expr));
1974 if cast_is_noop(datum.ty, t_out) {
1976 return DatumBlock::new(bcx, datum);
1979 let newval = match (k_in, k_out) {
1980 (cast_integral, cast_integral) => {
1981 let llexpr = datum.to_llscalarish(bcx);
1982 int_cast(bcx, ll_t_out, ll_t_in, llexpr, s_in)
1984 (cast_float, cast_float) => {
1985 let llexpr = datum.to_llscalarish(bcx);
1986 float_cast(bcx, ll_t_out, ll_t_in, llexpr)
1988 (cast_integral, cast_float) => {
1989 let llexpr = datum.to_llscalarish(bcx);
1991 SIToFP(bcx, llexpr, ll_t_out)
1992 } else { UIToFP(bcx, llexpr, ll_t_out) }
1994 (cast_float, cast_integral) => {
1995 let llexpr = datum.to_llscalarish(bcx);
1996 if ty::type_is_signed(t_out) {
1997 FPToSI(bcx, llexpr, ll_t_out)
1998 } else { FPToUI(bcx, llexpr, ll_t_out) }
2000 (cast_integral, cast_pointer) => {
2001 let llexpr = datum.to_llscalarish(bcx);
2002 IntToPtr(bcx, llexpr, ll_t_out)
2004 (cast_pointer, cast_integral) => {
2005 let llexpr = datum.to_llscalarish(bcx);
2006 PtrToInt(bcx, llexpr, ll_t_out)
2008 (cast_pointer, cast_pointer) => {
2009 let llexpr = datum.to_llscalarish(bcx);
2010 PointerCast(bcx, llexpr, ll_t_out)
2012 (cast_enum, cast_integral) |
2013 (cast_enum, cast_float) => {
2015 let repr = adt::represent_type(ccx, t_in);
2016 let datum = unpack_datum!(
2017 bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
2018 let llexpr_ptr = datum.to_llref();
2020 adt::trans_get_discr(bcx, &*repr, llexpr_ptr, Some(Type::i64(ccx)));
2022 cast_integral => int_cast(bcx, ll_t_out,
2023 val_ty(lldiscrim_a),
2025 cast_float => SIToFP(bcx, lldiscrim_a, ll_t_out),
2027 ccx.sess().bug(format!("translating unsupported cast: \
2028 {} ({}) -> {} ({})",
2029 t_in.repr(bcx.tcx()),
2031 t_out.repr(bcx.tcx()),
2036 _ => ccx.sess().bug(format!("translating unsupported cast: \
2037 {} ({}) -> {} ({})",
2038 t_in.repr(bcx.tcx()),
2040 t_out.repr(bcx.tcx()),
2043 return immediate_rvalue_bcx(bcx, newval, t_out).to_expr_datumblock();
2046 fn trans_assign_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2051 -> Block<'blk, 'tcx> {
2052 let _icx = push_ctxt("trans_assign_op");
2055 debug!("trans_assign_op(expr={})", bcx.expr_to_string(expr));
2057 // User-defined operator methods cannot be used with `+=` etc right now
2058 assert!(!bcx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
2060 // Evaluate LHS (destination), which should be an lvalue
2061 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, dst, "assign_op"));
2062 assert!(!ty::type_needs_drop(bcx.tcx(), dst_datum.ty));
2063 let dst_ty = dst_datum.ty;
2064 let dst = load_ty(bcx, dst_datum.val, dst_datum.ty);
2067 let rhs_datum = unpack_datum!(bcx, trans(bcx, &*src));
2068 let rhs_ty = rhs_datum.ty;
2069 let rhs = rhs_datum.to_llscalarish(bcx);
2071 // Perform computation and store the result
2072 let result_datum = unpack_datum!(
2073 bcx, trans_eager_binop(bcx, expr, dst_datum.ty, op,
2074 dst_ty, dst, rhs_ty, rhs));
2075 return result_datum.store_to(bcx, dst_datum.val);
2078 fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2079 datum: Datum<'tcx, Expr>,
2081 -> DatumBlock<'blk, 'tcx, Expr> {
2084 // Ensure cleanup of `datum` if not already scheduled and obtain
2085 // a "by ref" pointer.
2086 let lv_datum = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "autoref", expr.id));
2088 // Compute final type. Note that we are loose with the region and
2089 // mutability, since those things don't matter in trans.
2090 let referent_ty = lv_datum.ty;
2091 let ptr_ty = ty::mk_imm_rptr(bcx.tcx(), ty::ReStatic, referent_ty);
2094 let llref = lv_datum.to_llref();
2096 // Construct the resulting datum, using what was the "by ref"
2097 // ValueRef of type `referent_ty` to be the "by value" ValueRef
2098 // of type `&referent_ty`.
2099 DatumBlock::new(bcx, Datum::new(llref, ptr_ty, RvalueExpr(Rvalue::new(ByValue))))
2102 fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2104 datum: Datum<'tcx, Expr>,
2106 -> DatumBlock<'blk, 'tcx, Expr> {
2108 let mut datum = datum;
2109 for i in range(0, times) {
2110 let method_call = MethodCall::autoderef(expr.id, i);
2111 datum = unpack_datum!(bcx, deref_once(bcx, expr, datum, method_call));
2113 DatumBlock { bcx: bcx, datum: datum }
2116 fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2118 datum: Datum<'tcx, Expr>,
2119 method_call: MethodCall)
2120 -> DatumBlock<'blk, 'tcx, Expr> {
2121 let ccx = bcx.ccx();
2123 debug!("deref_once(expr={}, datum={}, method_call={})",
2124 expr.repr(bcx.tcx()),
2125 datum.to_string(ccx),
2130 // Check for overloaded deref.
2131 let method_ty = ccx.tcx().method_map.borrow()
2132 .get(&method_call).map(|method| method.ty);
2133 let datum = match method_ty {
2134 Some(method_ty) => {
2135 // Overloaded. Evaluate `trans_overloaded_op`, which will
2136 // invoke the user's deref() method, which basically
2137 // converts from the `Smaht<T>` pointer that we have into
2138 // a `&T` pointer. We can then proceed down the normal
2139 // path (below) to dereference that `&T`.
2140 let datum = match method_call.adjustment {
2141 // Always perform an AutoPtr when applying an overloaded auto-deref
2142 ty::AutoDeref(_) => unpack_datum!(bcx, auto_ref(bcx, datum, expr)),
2146 let ref_ty = ty::ty_fn_ret(monomorphize_type(bcx, method_ty)).unwrap();
2147 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_deref");
2149 unpack_result!(bcx, trans_overloaded_op(bcx, expr, method_call,
2150 datum, Vec::new(), Some(SaveIn(scratch.val)),
2152 scratch.to_expr_datum()
2155 // Not overloaded. We already have a pointer we know how to deref.
2160 let r = match datum.ty.sty {
2161 ty::ty_uniq(content_ty) => {
2162 if ty::type_is_sized(bcx.tcx(), content_ty) {
2163 deref_owned_pointer(bcx, expr, datum, content_ty)
2165 // A fat pointer and an opened DST value have the same
2166 // representation just different types. Since there is no
2167 // temporary for `*e` here (because it is unsized), we cannot
2168 // emulate the sized object code path for running drop glue and
2169 // free. Instead, we schedule cleanup for `e`, turning it into
2171 let datum = unpack_datum!(
2172 bcx, datum.to_lvalue_datum(bcx, "deref", expr.id));
2174 let datum = Datum::new(datum.val, ty::mk_open(bcx.tcx(), content_ty), LvalueExpr);
2175 DatumBlock::new(bcx, datum)
2179 ty::ty_ptr(ty::mt { ty: content_ty, .. }) |
2180 ty::ty_rptr(_, ty::mt { ty: content_ty, .. }) => {
2181 if ty::type_is_sized(bcx.tcx(), content_ty) {
2182 let ptr = datum.to_llscalarish(bcx);
2184 // Always generate an lvalue datum, even if datum.mode is
2185 // an rvalue. This is because datum.mode is only an
2186 // rvalue for non-owning pointers like &T or *T, in which
2187 // case cleanup *is* scheduled elsewhere, by the true
2188 // owner (or, in the case of *T, by the user).
2189 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr))
2191 // A fat pointer and an opened DST value have the same representation
2192 // just different types.
2193 DatumBlock::new(bcx, Datum::new(datum.val,
2194 ty::mk_open(bcx.tcx(), content_ty),
2200 bcx.tcx().sess.span_bug(
2202 format!("deref invoked on expr of illegal type {}",
2203 datum.ty.repr(bcx.tcx())).as_slice());
2207 debug!("deref_once(expr={}, method_call={}, result={})",
2208 expr.id, method_call, r.datum.to_string(ccx));
2212 /// We microoptimize derefs of owned pointers a bit here. Basically, the idea is to make the
2213 /// deref of an rvalue result in an rvalue. This helps to avoid intermediate stack slots in the
2214 /// resulting LLVM. The idea here is that, if the `Box<T>` pointer is an rvalue, then we can
2215 /// schedule a *shallow* free of the `Box<T>` pointer, and then return a ByRef rvalue into the
2216 /// pointer. Because the free is shallow, it is legit to return an rvalue, because we know that
2217 /// the contents are not yet scheduled to be freed. The language rules ensure that the contents
2218 /// will be used (or moved) before the free occurs.
2219 fn deref_owned_pointer<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2221 datum: Datum<'tcx, Expr>,
2222 content_ty: Ty<'tcx>)
2223 -> DatumBlock<'blk, 'tcx, Expr> {
2225 RvalueExpr(Rvalue { mode: ByRef }) => {
2226 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2227 let ptr = Load(bcx, datum.val);
2228 if !type_is_zero_size(bcx.ccx(), content_ty) {
2229 bcx.fcx.schedule_free_value(scope, ptr, cleanup::HeapExchange, content_ty);
2232 RvalueExpr(Rvalue { mode: ByValue }) => {
2233 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2234 if !type_is_zero_size(bcx.ccx(), content_ty) {
2235 bcx.fcx.schedule_free_value(scope, datum.val, cleanup::HeapExchange,
2242 // If we had an rvalue in, we produce an rvalue out.
2243 let (llptr, kind) = match datum.kind {
2245 (Load(bcx, datum.val), LvalueExpr)
2247 RvalueExpr(Rvalue { mode: ByRef }) => {
2248 (Load(bcx, datum.val), RvalueExpr(Rvalue::new(ByRef)))
2250 RvalueExpr(Rvalue { mode: ByValue }) => {
2251 (datum.val, RvalueExpr(Rvalue::new(ByRef)))
2255 let datum = Datum { ty: content_ty, val: llptr, kind: kind };
2256 DatumBlock { bcx: bcx, datum: datum }