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::{self, ValueRef};
41 use middle::mem_categorization::Typer;
42 use middle::subst::{self, Substs};
43 use trans::{_match, adt, asm, base, callee, closure, consts, controlflow};
46 use trans::cleanup::{self, CleanupMethods};
53 use trans::monomorphize;
57 use middle::ty::{struct_fields, tup_fields};
58 use middle::ty::{AdjustDerefRef, AdjustReifyFnPointer, AutoUnsafe};
59 use middle::ty::{AutoPtr};
60 use middle::ty::{self, Ty};
61 use middle::ty::MethodCall;
62 use util::common::indenter;
63 use util::ppaux::Repr;
64 use trans::machine::{llsize_of, llsize_of_alloc};
65 use trans::type_::Type;
67 use syntax::{ast, ast_util, codemap};
68 use syntax::print::pprust::{expr_to_string};
70 use syntax::parse::token;
72 use std::iter::repeat;
76 // These are passed around by the code generating functions to track the
77 // destination of a computation's value.
79 #[derive(Copy, PartialEq)]
86 pub fn to_string(&self, ccx: &CrateContext) -> String {
88 SaveIn(v) => format!("SaveIn({})", ccx.tn().val_to_string(v)),
89 Ignore => "Ignore".to_string()
94 /// This function is equivalent to `trans(bcx, expr).store_to_dest(dest)` but it may generate
95 /// better optimized LLVM code.
96 pub fn trans_into<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
99 -> Block<'blk, 'tcx> {
102 if bcx.tcx().adjustments.borrow().contains_key(&expr.id) {
103 // use trans, which may be less efficient but
104 // which will perform the adjustments:
105 let datum = unpack_datum!(bcx, trans(bcx, expr));
106 return datum.store_to_dest(bcx, dest, expr.id)
109 debug!("trans_into() expr={}", expr.repr(bcx.tcx()));
111 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
115 bcx.fcx.push_ast_cleanup_scope(cleanup_debug_loc);
117 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
118 let kind = ty::expr_kind(bcx.tcx(), expr);
120 ty::LvalueExpr | ty::RvalueDatumExpr => {
121 trans_unadjusted(bcx, expr).store_to_dest(dest, expr.id)
123 ty::RvalueDpsExpr => {
124 trans_rvalue_dps_unadjusted(bcx, expr, dest)
126 ty::RvalueStmtExpr => {
127 trans_rvalue_stmt_unadjusted(bcx, expr)
131 bcx.fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id)
134 /// Translates an expression, returning a datum (and new block) encapsulating the result. When
135 /// possible, it is preferred to use `trans_into`, as that may avoid creating a temporary on the
137 pub fn trans<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
139 -> DatumBlock<'blk, 'tcx, Expr> {
140 debug!("trans(expr={})", bcx.expr_to_string(expr));
145 let cleanup_debug_loc = debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
149 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
150 let datum = unpack_datum!(bcx, trans_unadjusted(bcx, expr));
151 let datum = unpack_datum!(bcx, apply_adjustments(bcx, expr, datum));
152 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, expr.id);
153 return DatumBlock::new(bcx, datum);
156 pub fn get_len(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
157 GEPi(bcx, fat_ptr, &[0u, abi::FAT_PTR_EXTRA])
160 pub fn get_dataptr(bcx: Block, fat_ptr: ValueRef) -> ValueRef {
161 GEPi(bcx, fat_ptr, &[0u, abi::FAT_PTR_ADDR])
164 /// Helper for trans that apply adjustments from `expr` to `datum`, which should be the unadjusted
165 /// translation of `expr`.
166 fn apply_adjustments<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
168 datum: Datum<'tcx, Expr>)
169 -> DatumBlock<'blk, 'tcx, Expr> {
171 let mut datum = datum;
172 let adjustment = match bcx.tcx().adjustments.borrow().get(&expr.id).cloned() {
174 return DatumBlock::new(bcx, datum);
178 debug!("unadjusted datum for expr {}: {}, adjustment={}",
179 expr.repr(bcx.tcx()),
180 datum.to_string(bcx.ccx()),
181 adjustment.repr(bcx.tcx()));
183 AdjustReifyFnPointer(_def_id) => {
184 // FIXME(#19925) once fn item types are
185 // zero-sized, we'll need to do something here
187 AdjustDerefRef(ref adj) => {
188 let (autoderefs, use_autoref) = match adj.autoref {
189 // Extracting a value from a box counts as a deref, but if we are
190 // just converting Box<[T, ..n]> to Box<[T]> we aren't really doing
191 // a deref (and wouldn't if we could treat Box like a normal struct).
192 Some(ty::AutoUnsizeUniq(..)) => (adj.autoderefs - 1, true),
193 // We are a bit paranoid about adjustments and thus might have a re-
194 // borrow here which merely derefs and then refs again (it might have
195 // a different region or mutability, but we don't care here. It might
196 // also be just in case we need to unsize. But if there are no nested
197 // adjustments then it should be a no-op).
198 Some(ty::AutoPtr(_, _, None)) if adj.autoderefs == 1 => {
200 // Don't skip a conversion from Box<T> to &T, etc.
202 let method_call = MethodCall::autoderef(expr.id, adj.autoderefs-1);
203 let method = bcx.tcx().method_map.borrow().get(&method_call).is_some();
205 // Don't skip an overloaded deref.
206 (adj.autoderefs, true)
208 (adj.autoderefs - 1, false)
211 _ => (adj.autoderefs, true),
214 _ => (adj.autoderefs, true)
219 let lval = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "auto_deref", expr.id));
220 datum = unpack_datum!(
221 bcx, deref_multiple(bcx, expr, lval.to_expr_datum(), autoderefs));
224 // (You might think there is a more elegant way to do this than a
225 // use_autoref bool, but then you remember that the borrow checker exists).
226 if let (true, &Some(ref a)) = (use_autoref, &adj.autoref) {
227 datum = unpack_datum!(bcx, apply_autoref(a,
234 debug!("after adjustments, datum={}", datum.to_string(bcx.ccx()));
235 return DatumBlock::new(bcx, datum);
237 fn apply_autoref<'blk, 'tcx>(autoref: &ty::AutoRef<'tcx>,
238 bcx: Block<'blk, 'tcx>,
240 datum: Datum<'tcx, Expr>)
241 -> DatumBlock<'blk, 'tcx, Expr> {
243 let mut datum = datum;
245 let datum = match autoref {
246 &AutoPtr(_, _, ref a) | &AutoUnsafe(_, ref a) => {
249 &Some(box ref a) => {
250 datum = unpack_datum!(bcx, apply_autoref(a, bcx, expr, datum));
254 unpack_datum!(bcx, ref_ptr(bcx, expr, datum))
256 &ty::AutoUnsize(ref k) => {
257 debug!(" AutoUnsize");
258 unpack_datum!(bcx, unsize_expr(bcx, expr, datum, k))
261 &ty::AutoUnsizeUniq(ty::UnsizeLength(len)) => {
262 debug!(" AutoUnsizeUniq(UnsizeLength)");
263 unpack_datum!(bcx, unsize_unique_vec(bcx, expr, datum, len))
265 &ty::AutoUnsizeUniq(ref k) => {
266 debug!(" AutoUnsizeUniq");
267 unpack_datum!(bcx, unsize_unique_expr(bcx, expr, datum, k))
271 DatumBlock::new(bcx, datum)
274 fn ref_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
276 datum: Datum<'tcx, Expr>)
277 -> DatumBlock<'blk, 'tcx, Expr> {
278 debug!("ref_ptr(expr={}, datum={})",
279 expr.repr(bcx.tcx()),
280 datum.to_string(bcx.ccx()));
282 if !type_is_sized(bcx.tcx(), datum.ty) {
283 debug!("Taking address of unsized type {}",
284 bcx.ty_to_string(datum.ty));
285 ref_fat_ptr(bcx, expr, datum)
287 debug!("Taking address of sized type {}",
288 bcx.ty_to_string(datum.ty));
289 auto_ref(bcx, datum, expr)
293 // Retrieve the information we are losing (making dynamic) in an unsizing
295 // When making a dtor, we need to do different things depending on the
296 // ownership of the object.. mk_ty is a function for turning `unadjusted_ty`
297 // into a type to be destructed. If we want to end up with a Box pointer,
298 // then mk_ty should make a Box pointer (T -> Box<T>), if we want a
299 // borrowed reference then it should be T -> &T.
300 fn unsized_info<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
301 kind: &ty::UnsizeKind<'tcx>,
303 unadjusted_ty: Ty<'tcx>,
304 mk_ty: F) -> ValueRef where
305 F: FnOnce(Ty<'tcx>) -> Ty<'tcx>,
307 // FIXME(#19596) workaround: `|t| t` causes monomorphization recursion
308 fn identity<T>(t: T) -> T { t }
310 debug!("unsized_info(kind={:?}, id={}, unadjusted_ty={})",
311 kind, id, unadjusted_ty.repr(bcx.tcx()));
313 &ty::UnsizeLength(len) => C_uint(bcx.ccx(), len),
314 &ty::UnsizeStruct(box ref k, tp_index) => match unadjusted_ty.sty {
315 ty::ty_struct(_, ref substs) => {
316 let ty_substs = substs.types.get_slice(subst::TypeSpace);
317 // The dtor for a field treats it like a value, so mk_ty
318 // should just be the identity function.
319 unsized_info(bcx, k, id, ty_substs[tp_index], identity)
321 _ => bcx.sess().bug(&format!("UnsizeStruct with bad sty: {}",
322 bcx.ty_to_string(unadjusted_ty))[])
324 &ty::UnsizeVtable(ty::TyTrait { ref principal, .. }, _) => {
325 // Note that we preserve binding levels here:
326 let substs = principal.0.substs.with_self_ty(unadjusted_ty).erase_regions();
327 let substs = bcx.tcx().mk_substs(substs);
329 ty::Binder(Rc::new(ty::TraitRef { def_id: principal.def_id(),
331 let trait_ref = bcx.monomorphize(&trait_ref);
332 let box_ty = mk_ty(unadjusted_ty);
334 meth::get_vtable(bcx, box_ty, trait_ref),
335 Type::vtable_ptr(bcx.ccx()))
340 fn unsize_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
342 datum: Datum<'tcx, Expr>,
343 k: &ty::UnsizeKind<'tcx>)
344 -> DatumBlock<'blk, 'tcx, Expr> {
346 let datum_ty = datum.ty;
347 let unsized_ty = ty::unsize_ty(tcx, datum_ty, k, expr.span);
348 debug!("unsized_ty={}", unsized_ty.repr(bcx.tcx()));
349 let dest_ty = ty::mk_open(tcx, unsized_ty);
350 debug!("dest_ty={}", unsized_ty.repr(bcx.tcx()));
351 // Closures for extracting and manipulating the data and payload parts of
353 let info = |: bcx, _val| unsized_info(bcx,
358 tcx.mk_region(ty::ReStatic),
361 mutbl: ast::MutImmutable
364 ty::UnsizeStruct(..) =>
365 into_fat_ptr(bcx, expr, datum, dest_ty, |bcx, val| {
366 PointerCast(bcx, val, type_of::type_of(bcx.ccx(), unsized_ty).ptr_to())
368 ty::UnsizeLength(..) =>
369 into_fat_ptr(bcx, expr, datum, dest_ty, |bcx, val| {
370 GEPi(bcx, val, &[0u, 0u])
372 ty::UnsizeVtable(..) =>
373 into_fat_ptr(bcx, expr, datum, dest_ty, |_bcx, val| {
374 PointerCast(bcx, val, Type::i8p(bcx.ccx()))
379 fn ref_fat_ptr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
381 datum: Datum<'tcx, Expr>)
382 -> DatumBlock<'blk, 'tcx, Expr> {
384 let dest_ty = ty::close_type(tcx, datum.ty);
385 let base = |: bcx, val| Load(bcx, get_dataptr(bcx, val));
386 let len = |: bcx, val| Load(bcx, get_len(bcx, val));
387 into_fat_ptr(bcx, expr, datum, dest_ty, base, len)
390 fn into_fat_ptr<'blk, 'tcx, F, G>(bcx: Block<'blk, 'tcx>,
392 datum: Datum<'tcx, Expr>,
396 -> DatumBlock<'blk, 'tcx, Expr> where
397 F: FnOnce(Block<'blk, 'tcx>, ValueRef) -> ValueRef,
398 G: FnOnce(Block<'blk, 'tcx>, ValueRef) -> ValueRef,
403 let lval = unpack_datum!(bcx,
404 datum.to_lvalue_datum(bcx, "into_fat_ptr", expr.id));
405 let base = base(bcx, lval.val);
406 let info = info(bcx, lval.val);
408 let scratch = rvalue_scratch_datum(bcx, dest_ty, "__fat_ptr");
409 Store(bcx, base, get_dataptr(bcx, scratch.val));
410 Store(bcx, info, get_len(bcx, scratch.val));
412 DatumBlock::new(bcx, scratch.to_expr_datum())
415 fn unsize_unique_vec<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
417 datum: Datum<'tcx, Expr>,
419 -> DatumBlock<'blk, 'tcx, Expr> {
423 let datum_ty = datum.ty;
425 let lval = unpack_datum!(bcx,
426 datum.to_lvalue_datum(bcx, "unsize_unique_vec", expr.id));
428 let ll_len = C_uint(bcx.ccx(), len);
429 let unit_ty = ty::sequence_element_type(tcx, ty::type_content(datum_ty));
430 let vec_ty = ty::mk_uniq(tcx, ty::mk_vec(tcx, unit_ty, None));
431 let scratch = rvalue_scratch_datum(bcx, vec_ty, "__unsize_unique");
433 let base = get_dataptr(bcx, scratch.val);
434 let base = PointerCast(bcx,
436 type_of::type_of(bcx.ccx(), datum_ty).ptr_to());
437 bcx = lval.store_to(bcx, base);
439 Store(bcx, ll_len, get_len(bcx, scratch.val));
440 DatumBlock::new(bcx, scratch.to_expr_datum())
443 fn unsize_unique_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
445 datum: Datum<'tcx, Expr>,
446 k: &ty::UnsizeKind<'tcx>)
447 -> DatumBlock<'blk, 'tcx, Expr> {
451 let datum_ty = datum.ty;
452 let unboxed_ty = match datum_ty.sty {
454 _ => bcx.sess().bug(&format!("Expected ty_uniq, found {}",
455 bcx.ty_to_string(datum_ty))[])
457 let result_ty = ty::mk_uniq(tcx, ty::unsize_ty(tcx, unboxed_ty, k, expr.span));
459 let lval = unpack_datum!(bcx,
460 datum.to_lvalue_datum(bcx, "unsize_unique_expr", expr.id));
462 let scratch = rvalue_scratch_datum(bcx, result_ty, "__uniq_fat_ptr");
463 let llbox_ty = type_of::type_of(bcx.ccx(), datum_ty);
464 let base = PointerCast(bcx, get_dataptr(bcx, scratch.val), llbox_ty.ptr_to());
465 bcx = lval.store_to(bcx, base);
467 let info = unsized_info(bcx, k, expr.id, unboxed_ty, |t| ty::mk_uniq(tcx, t));
468 Store(bcx, info, get_len(bcx, scratch.val));
470 let scratch = unpack_datum!(bcx,
471 scratch.to_expr_datum().to_lvalue_datum(bcx,
472 "fresh_uniq_fat_ptr",
475 DatumBlock::new(bcx, scratch.to_expr_datum())
479 /// Translates an expression in "lvalue" mode -- meaning that it returns a reference to the memory
480 /// that the expr represents.
482 /// If this expression is an rvalue, this implies introducing a temporary. In other words,
483 /// something like `x().f` is translated into roughly the equivalent of
485 /// { tmp = x(); tmp.f }
486 pub fn trans_to_lvalue<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
489 -> DatumBlock<'blk, 'tcx, Lvalue> {
491 let datum = unpack_datum!(bcx, trans(bcx, expr));
492 return datum.to_lvalue_datum(bcx, name, expr.id);
495 /// A version of `trans` that ignores adjustments. You almost certainly do not want to call this
497 fn trans_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
499 -> DatumBlock<'blk, 'tcx, Expr> {
502 debug!("trans_unadjusted(expr={})", bcx.expr_to_string(expr));
503 let _indenter = indenter();
505 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
507 return match ty::expr_kind(bcx.tcx(), expr) {
508 ty::LvalueExpr | ty::RvalueDatumExpr => {
509 let datum = unpack_datum!(bcx, {
510 trans_datum_unadjusted(bcx, expr)
513 DatumBlock {bcx: bcx, datum: datum}
516 ty::RvalueStmtExpr => {
517 bcx = trans_rvalue_stmt_unadjusted(bcx, expr);
518 nil(bcx, expr_ty(bcx, expr))
521 ty::RvalueDpsExpr => {
522 let ty = expr_ty(bcx, expr);
523 if type_is_zero_size(bcx.ccx(), ty) {
524 bcx = trans_rvalue_dps_unadjusted(bcx, expr, Ignore);
527 let scratch = rvalue_scratch_datum(bcx, ty, "");
528 bcx = trans_rvalue_dps_unadjusted(
529 bcx, expr, SaveIn(scratch.val));
531 // Note: this is not obviously a good idea. It causes
532 // immediate values to be loaded immediately after a
533 // return from a call or other similar expression,
534 // which in turn leads to alloca's having shorter
535 // lifetimes and hence larger stack frames. However,
536 // in turn it can lead to more register pressure.
537 // Still, in practice it seems to increase
538 // performance, since we have fewer problems with
540 let scratch = unpack_datum!(
541 bcx, scratch.to_appropriate_datum(bcx));
543 DatumBlock::new(bcx, scratch.to_expr_datum())
548 fn nil<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, ty: Ty<'tcx>)
549 -> DatumBlock<'blk, 'tcx, Expr> {
550 let llval = C_undef(type_of::type_of(bcx.ccx(), ty));
551 let datum = immediate_rvalue(llval, ty);
552 DatumBlock::new(bcx, datum.to_expr_datum())
556 fn trans_datum_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
558 -> DatumBlock<'blk, 'tcx, Expr> {
561 let _icx = push_ctxt("trans_datum_unadjusted");
564 ast::ExprParen(ref e) => {
567 ast::ExprPath(_) | ast::ExprQPath(_) => {
568 trans_def(bcx, expr, bcx.def(expr.id))
570 ast::ExprField(ref base, ident) => {
571 trans_rec_field(bcx, &**base, ident.node)
573 ast::ExprTupField(ref base, idx) => {
574 trans_rec_tup_field(bcx, &**base, idx.node)
576 ast::ExprIndex(ref base, ref idx) => {
577 trans_index(bcx, expr, &**base, &**idx, MethodCall::expr(expr.id))
579 ast::ExprBox(_, ref contents) => {
580 // Special case for `Box<T>`
581 let box_ty = expr_ty(bcx, expr);
582 let contents_ty = expr_ty(bcx, &**contents);
585 trans_uniq_expr(bcx, box_ty, &**contents, contents_ty)
587 _ => bcx.sess().span_bug(expr.span,
588 "expected unique box")
592 ast::ExprLit(ref lit) => trans_immediate_lit(bcx, expr, &**lit),
593 ast::ExprBinary(op, ref lhs, ref rhs) => {
594 trans_binary(bcx, expr, op, &**lhs, &**rhs)
596 ast::ExprUnary(op, ref x) => {
597 trans_unary(bcx, expr, op, &**x)
599 ast::ExprAddrOf(_, ref x) => {
601 ast::ExprRepeat(..) | ast::ExprVec(..) => {
602 // Special case for slices.
603 let cleanup_debug_loc =
604 debuginfo::get_cleanup_debug_loc_for_ast_node(bcx.ccx(),
608 fcx.push_ast_cleanup_scope(cleanup_debug_loc);
609 let datum = unpack_datum!(
610 bcx, tvec::trans_slice_vec(bcx, expr, &**x));
611 bcx = fcx.pop_and_trans_ast_cleanup_scope(bcx, x.id);
612 DatumBlock::new(bcx, datum)
615 trans_addr_of(bcx, expr, &**x)
619 ast::ExprCast(ref val, _) => {
620 // Datum output mode means this is a scalar cast:
621 trans_imm_cast(bcx, &**val, expr.id)
624 bcx.tcx().sess.span_bug(
626 &format!("trans_rvalue_datum_unadjusted reached \
627 fall-through case: {:?}",
633 fn trans_field<'blk, 'tcx, F>(bcx: Block<'blk, 'tcx>,
636 -> DatumBlock<'blk, 'tcx, Expr> where
637 F: FnOnce(&'blk ty::ctxt<'tcx>, &[ty::field<'tcx>]) -> uint,
640 let _icx = push_ctxt("trans_rec_field");
642 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, base, "field"));
643 let bare_ty = ty::unopen_type(base_datum.ty);
644 let repr = adt::represent_type(bcx.ccx(), bare_ty);
645 with_field_tys(bcx.tcx(), bare_ty, None, move |discr, field_tys| {
646 let ix = get_idx(bcx.tcx(), field_tys);
647 let d = base_datum.get_element(
650 |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, ix));
652 if type_is_sized(bcx.tcx(), d.ty) {
653 DatumBlock { datum: d.to_expr_datum(), bcx: bcx }
655 let scratch = rvalue_scratch_datum(bcx, ty::mk_open(bcx.tcx(), d.ty), "");
656 Store(bcx, d.val, get_dataptr(bcx, scratch.val));
657 let info = Load(bcx, get_len(bcx, base_datum.val));
658 Store(bcx, info, get_len(bcx, scratch.val));
660 DatumBlock::new(bcx, scratch.to_expr_datum())
667 /// Translates `base.field`.
668 fn trans_rec_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
671 -> DatumBlock<'blk, 'tcx, Expr> {
672 trans_field(bcx, base, |tcx, field_tys| ty::field_idx_strict(tcx, field.name, field_tys))
675 /// Translates `base.<idx>`.
676 fn trans_rec_tup_field<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
679 -> DatumBlock<'blk, 'tcx, Expr> {
680 trans_field(bcx, base, |_, _| idx)
683 fn trans_index<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
684 index_expr: &ast::Expr,
687 method_call: MethodCall)
688 -> DatumBlock<'blk, 'tcx, Expr> {
689 //! Translates `base[idx]`.
691 let _icx = push_ctxt("trans_index");
695 // Check for overloaded index.
696 let method_ty = ccx.tcx()
700 .map(|method| method.ty);
701 let elt_datum = match method_ty {
703 let method_ty = monomorphize_type(bcx, method_ty);
705 let base_datum = unpack_datum!(bcx, trans(bcx, base));
707 // Translate index expression.
708 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
710 let ref_ty = // invoked methods have LB regions instantiated:
711 ty::assert_no_late_bound_regions(
712 bcx.tcx(), &ty::ty_fn_ret(method_ty)).unwrap();
713 let elt_ty = match ty::deref(ref_ty, true) {
715 bcx.tcx().sess.span_bug(index_expr.span,
716 "index method didn't return a \
717 dereferenceable type?!")
719 Some(elt_tm) => elt_tm.ty,
722 // Overloaded. Evaluate `trans_overloaded_op`, which will
723 // invoke the user's index() method, which basically yields
724 // a `&T` pointer. We can then proceed down the normal
725 // path (below) to dereference that `&T`.
726 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_index_elt");
728 trans_overloaded_op(bcx,
732 vec![(ix_datum, idx.id)],
733 Some(SaveIn(scratch.val)),
735 let datum = scratch.to_expr_datum();
736 if type_is_sized(bcx.tcx(), elt_ty) {
737 Datum::new(datum.to_llscalarish(bcx), elt_ty, LvalueExpr)
739 Datum::new(datum.val, ty::mk_open(bcx.tcx(), elt_ty), LvalueExpr)
743 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx,
747 // Translate index expression and cast to a suitable LLVM integer.
748 // Rust is less strict than LLVM in this regard.
749 let ix_datum = unpack_datum!(bcx, trans(bcx, idx));
750 let ix_val = ix_datum.to_llscalarish(bcx);
751 let ix_size = machine::llbitsize_of_real(bcx.ccx(),
753 let int_size = machine::llbitsize_of_real(bcx.ccx(),
756 if ix_size < int_size {
757 if ty::type_is_signed(expr_ty(bcx, idx)) {
758 SExt(bcx, ix_val, ccx.int_type())
759 } else { ZExt(bcx, ix_val, ccx.int_type()) }
760 } else if ix_size > int_size {
761 Trunc(bcx, ix_val, ccx.int_type())
769 ty::sequence_element_type(bcx.tcx(),
771 base::maybe_name_value(bcx.ccx(), vt.llunit_size, "unit_sz");
773 let (base, len) = base_datum.get_vec_base_and_len(bcx);
775 debug!("trans_index: base {}", bcx.val_to_string(base));
776 debug!("trans_index: len {}", bcx.val_to_string(len));
778 let bounds_check = ICmp(bcx, llvm::IntUGE, ix_val, len);
779 let expect = ccx.get_intrinsic(&("llvm.expect.i1"));
780 let expected = Call(bcx,
782 &[bounds_check, C_bool(ccx, false)],
784 bcx = with_cond(bcx, expected, |bcx| {
785 controlflow::trans_fail_bounds_check(bcx,
790 let elt = InBoundsGEP(bcx, base, &[ix_val]);
791 let elt = PointerCast(bcx, elt, vt.llunit_ty.ptr_to());
792 Datum::new(elt, vt.unit_ty, LvalueExpr)
796 DatumBlock::new(bcx, elt_datum)
799 fn trans_def<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
800 ref_expr: &ast::Expr,
802 -> DatumBlock<'blk, 'tcx, Expr> {
803 //! Translates a reference to a path.
805 let _icx = push_ctxt("trans_def_lvalue");
807 def::DefFn(..) | def::DefStaticMethod(..) | def::DefMethod(..) |
808 def::DefStruct(_) | def::DefVariant(..) => {
809 let datum = trans_def_fn_unadjusted(bcx.ccx(), ref_expr, def,
810 bcx.fcx.param_substs);
811 DatumBlock::new(bcx, datum.to_expr_datum())
813 def::DefStatic(did, _) => {
814 // There are two things that may happen here:
815 // 1) If the static item is defined in this crate, it will be
816 // translated using `get_item_val`, and we return a pointer to
818 // 2) If the static item is defined in another crate then we add
819 // (or reuse) a declaration of an external global, and return a
821 let const_ty = expr_ty(bcx, ref_expr);
823 fn get_val<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, did: ast::DefId,
824 const_ty: Ty<'tcx>) -> ValueRef {
825 // For external constants, we don't inline.
826 if did.krate == ast::LOCAL_CRATE {
829 // The LLVM global has the type of its initializer,
830 // which may not be equal to the enum's type for
832 let val = base::get_item_val(bcx.ccx(), did.node);
833 let pty = type_of::type_of(bcx.ccx(), const_ty).ptr_to();
834 PointerCast(bcx, val, pty)
837 base::get_extern_const(bcx.ccx(), did, const_ty)
840 let val = get_val(bcx, did, const_ty);
841 DatumBlock::new(bcx, Datum::new(val, const_ty, LvalueExpr))
843 def::DefConst(did) => {
844 // First, inline any external constants into the local crate so we
845 // can be sure to get the LLVM value corresponding to it.
846 let did = inline::maybe_instantiate_inline(bcx.ccx(), did);
847 if did.krate != ast::LOCAL_CRATE {
848 bcx.tcx().sess.span_bug(ref_expr.span,
849 "cross crate constant could not \
852 let val = base::get_item_val(bcx.ccx(), did.node);
854 // Next, we need to crate a ByRef rvalue datum to return. We can't
855 // use the normal .to_ref_datum() function because the type of
856 // `val` is not actually the same as `const_ty`.
858 // To get around this, we make a custom alloca slot with the
859 // appropriate type (const_ty), and then we cast it to a pointer of
860 // typeof(val), store the value, and then hand this slot over to
861 // the datum infrastructure.
862 let const_ty = expr_ty(bcx, ref_expr);
863 let llty = type_of::type_of(bcx.ccx(), const_ty);
864 let slot = alloca(bcx, llty, "const");
865 let pty = Type::from_ref(unsafe { llvm::LLVMTypeOf(val) }).ptr_to();
866 Store(bcx, val, PointerCast(bcx, slot, pty));
868 let datum = Datum::new(slot, const_ty, Rvalue::new(ByRef));
869 DatumBlock::new(bcx, datum.to_expr_datum())
872 DatumBlock::new(bcx, trans_local_var(bcx, def).to_expr_datum())
877 fn trans_rvalue_stmt_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
879 -> Block<'blk, 'tcx> {
881 let _icx = push_ctxt("trans_rvalue_stmt");
883 if bcx.unreachable.get() {
887 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
890 ast::ExprParen(ref e) => {
891 trans_into(bcx, &**e, Ignore)
893 ast::ExprBreak(label_opt) => {
894 controlflow::trans_break(bcx, expr.id, label_opt)
896 ast::ExprAgain(label_opt) => {
897 controlflow::trans_cont(bcx, expr.id, label_opt)
899 ast::ExprRet(ref ex) => {
900 // Check to see if the return expression itself is reachable.
901 // This can occur when the inner expression contains a return
902 let reachable = if let Some(ref cfg) = bcx.fcx.cfg {
903 cfg.node_is_reachable(expr.id)
909 controlflow::trans_ret(bcx, ex.as_ref().map(|e| &**e))
911 // If it's not reachable, just translate the inner expression
912 // directly. This avoids having to manage a return slot when
913 // it won't actually be used anyway.
914 if let &Some(ref x) = ex {
915 bcx = trans_into(bcx, &**x, Ignore);
917 // Mark the end of the block as unreachable. Once we get to
918 // a return expression, there's no more we should be doing
924 ast::ExprWhile(ref cond, ref body, _) => {
925 controlflow::trans_while(bcx, expr.id, &**cond, &**body)
927 ast::ExprForLoop(ref pat, ref head, ref body, _) => {
928 controlflow::trans_for(bcx,
934 ast::ExprLoop(ref body, _) => {
935 controlflow::trans_loop(bcx, expr.id, &**body)
937 ast::ExprAssign(ref dst, ref src) => {
938 let src_datum = unpack_datum!(bcx, trans(bcx, &**src));
939 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &**dst, "assign"));
941 if type_needs_drop(bcx.tcx(), dst_datum.ty) {
942 // If there are destructors involved, make sure we
943 // are copying from an rvalue, since that cannot possible
944 // alias an lvalue. We are concerned about code like:
952 // where e.g. a : Option<Foo> and a.b :
953 // Option<Foo>. In that case, freeing `a` before the
954 // assignment may also free `a.b`!
956 // We could avoid this intermediary with some analysis
957 // to determine whether `dst` may possibly own `src`.
958 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
959 let src_datum = unpack_datum!(
960 bcx, src_datum.to_rvalue_datum(bcx, "ExprAssign"));
961 bcx = glue::drop_ty(bcx,
964 Some(NodeInfo { id: expr.id, span: expr.span }));
965 src_datum.store_to(bcx, dst_datum.val)
967 src_datum.store_to(bcx, dst_datum.val)
970 ast::ExprAssignOp(op, ref dst, ref src) => {
971 trans_assign_op(bcx, expr, op, &**dst, &**src)
973 ast::ExprInlineAsm(ref a) => {
974 asm::trans_inline_asm(bcx, a)
977 bcx.tcx().sess.span_bug(
979 &format!("trans_rvalue_stmt_unadjusted reached \
980 fall-through case: {:?}",
986 fn trans_rvalue_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
989 -> Block<'blk, 'tcx> {
990 let _icx = push_ctxt("trans_rvalue_dps_unadjusted");
994 debuginfo::set_source_location(bcx.fcx, expr.id, expr.span);
997 ast::ExprParen(ref e) => {
998 trans_into(bcx, &**e, dest)
1000 ast::ExprPath(_) | ast::ExprQPath(_) => {
1001 trans_def_dps_unadjusted(bcx, expr, bcx.def(expr.id), dest)
1003 ast::ExprIf(ref cond, ref thn, ref els) => {
1004 controlflow::trans_if(bcx, expr.id, &**cond, &**thn, els.as_ref().map(|e| &**e), dest)
1006 ast::ExprMatch(ref discr, ref arms, _) => {
1007 _match::trans_match(bcx, expr, &**discr, &arms[], dest)
1009 ast::ExprBlock(ref blk) => {
1010 controlflow::trans_block(bcx, &**blk, dest)
1012 ast::ExprStruct(_, ref fields, ref base) => {
1015 base.as_ref().map(|e| &**e),
1018 node_id_type(bcx, expr.id),
1021 ast::ExprRange(ref start, ref end) => {
1022 // FIXME it is just not right that we are synthesising ast nodes in
1024 fn make_field(field_name: &str, expr: P<ast::Expr>) -> ast::Field {
1026 ident: codemap::dummy_spanned(token::str_to_ident(field_name)),
1028 span: codemap::DUMMY_SP,
1032 // A range just desugars into a struct.
1033 // Note that the type of the start and end may not be the same, but
1034 // they should only differ in their lifetime, which should not matter
1036 let (did, fields, ty_params) = match (start, end) {
1037 (&Some(ref start), &Some(ref end)) => {
1039 let fields = vec![make_field("start", start.clone()),
1040 make_field("end", end.clone())];
1041 (tcx.lang_items.range_struct(), fields, vec![node_id_type(bcx, start.id)])
1043 (&Some(ref start), &None) => {
1044 // Desugar to RangeFrom
1045 let fields = vec![make_field("start", start.clone())];
1046 (tcx.lang_items.range_from_struct(), fields, vec![node_id_type(bcx, start.id)])
1048 (&None, &Some(ref end)) => {
1049 // Desugar to RangeTo
1050 let fields = vec![make_field("end", end.clone())];
1051 (tcx.lang_items.range_to_struct(), fields, vec![node_id_type(bcx, end.id)])
1054 // Desugar to FullRange
1055 (tcx.lang_items.full_range_struct(), vec![], vec![])
1059 if let Some(did) = did {
1060 let substs = Substs::new_type(ty_params, vec![]);
1066 ty::mk_struct(tcx, did, tcx.mk_substs(substs)),
1069 tcx.sess.span_bug(expr.span,
1070 "No lang item for ranges (how did we get this far?)")
1073 ast::ExprTup(ref args) => {
1074 let numbered_fields: Vec<(uint, &ast::Expr)> =
1075 args.iter().enumerate().map(|(i, arg)| (i, &**arg)).collect();
1082 Some(NodeInfo { id: expr.id, span: expr.span }))
1084 ast::ExprLit(ref lit) => {
1086 ast::LitStr(ref s, _) => {
1087 tvec::trans_lit_str(bcx, expr, (*s).clone(), dest)
1092 .span_bug(expr.span,
1093 "trans_rvalue_dps_unadjusted shouldn't be \
1094 translating this type of literal")
1098 ast::ExprVec(..) | ast::ExprRepeat(..) => {
1099 tvec::trans_fixed_vstore(bcx, expr, dest)
1101 ast::ExprClosure(_, _, ref decl, ref body) => {
1102 // Check the side-table to see whether this is an unboxed
1103 // closure or an older, legacy style closure. Store this
1104 // into a variable to ensure the the RefCell-lock is
1105 // released before we recurse.
1106 let is_unboxed_closure =
1107 bcx.tcx().unboxed_closures.borrow().contains_key(&ast_util::local_def(expr.id));
1108 if is_unboxed_closure {
1109 closure::trans_unboxed_closure(bcx, &**decl, &**body, expr.id, dest)
1111 let expr_ty = expr_ty(bcx, expr);
1112 let store = ty::ty_closure_store(expr_ty);
1113 debug!("translating block function {} with type {}",
1114 expr_to_string(expr), expr_ty.repr(tcx));
1115 closure::trans_expr_fn(bcx, store, &**decl, &**body, expr.id, dest)
1118 ast::ExprCall(ref f, ref args) => {
1119 if bcx.tcx().is_method_call(expr.id) {
1120 trans_overloaded_call(bcx,
1126 callee::trans_call(bcx,
1129 callee::ArgExprs(&args[]),
1133 ast::ExprMethodCall(_, _, ref args) => {
1134 callee::trans_method_call(bcx,
1137 callee::ArgExprs(&args[]),
1140 ast::ExprBinary(op, ref lhs, ref rhs) => {
1141 // if not overloaded, would be RvalueDatumExpr
1142 let lhs = unpack_datum!(bcx, trans(bcx, &**lhs));
1143 let rhs_datum = unpack_datum!(bcx, trans(bcx, &**rhs));
1144 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), lhs,
1145 vec![(rhs_datum, rhs.id)], Some(dest),
1146 !ast_util::is_by_value_binop(op)).bcx
1148 ast::ExprUnary(op, ref subexpr) => {
1149 // if not overloaded, would be RvalueDatumExpr
1150 let arg = unpack_datum!(bcx, trans(bcx, &**subexpr));
1151 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id),
1152 arg, Vec::new(), Some(dest), !ast_util::is_by_value_unop(op)).bcx
1154 ast::ExprIndex(ref base, ref idx) => {
1155 // if not overloaded, would be RvalueDatumExpr
1156 let base = unpack_datum!(bcx, trans(bcx, &**base));
1157 let idx_datum = unpack_datum!(bcx, trans(bcx, &**idx));
1158 trans_overloaded_op(bcx, expr, MethodCall::expr(expr.id), base,
1159 vec![(idx_datum, idx.id)], Some(dest), true).bcx
1161 ast::ExprCast(ref val, _) => {
1162 // DPS output mode means this is a trait cast:
1163 if ty::type_is_trait(node_id_type(bcx, expr.id)) {
1165 bcx.tcx().object_cast_map.borrow()
1167 .map(|t| (*t).clone())
1169 let trait_ref = bcx.monomorphize(&trait_ref);
1170 let datum = unpack_datum!(bcx, trans(bcx, &**val));
1171 meth::trans_trait_cast(bcx, datum, expr.id,
1174 bcx.tcx().sess.span_bug(expr.span,
1175 "expr_cast of non-trait");
1178 ast::ExprAssignOp(op, ref dst, ref src) => {
1179 trans_assign_op(bcx, expr, op, &**dst, &**src)
1182 bcx.tcx().sess.span_bug(
1184 &format!("trans_rvalue_dps_unadjusted reached fall-through \
1191 fn trans_def_dps_unadjusted<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1192 ref_expr: &ast::Expr,
1195 -> Block<'blk, 'tcx> {
1196 let _icx = push_ctxt("trans_def_dps_unadjusted");
1198 let lldest = match dest {
1199 SaveIn(lldest) => lldest,
1200 Ignore => { return bcx; }
1204 def::DefVariant(tid, vid, _) => {
1205 let variant_info = ty::enum_variant_with_id(bcx.tcx(), tid, vid);
1206 if variant_info.args.len() > 0u {
1208 let llfn = callee::trans_fn_ref(bcx.ccx(), vid,
1209 ExprId(ref_expr.id),
1210 bcx.fcx.param_substs).val;
1211 Store(bcx, llfn, lldest);
1215 let ty = expr_ty(bcx, ref_expr);
1216 let repr = adt::represent_type(bcx.ccx(), ty);
1217 adt::trans_set_discr(bcx, &*repr, lldest,
1218 variant_info.disr_val);
1222 def::DefStruct(_) => {
1223 let ty = expr_ty(bcx, ref_expr);
1225 ty::ty_struct(did, _) if ty::has_dtor(bcx.tcx(), did) => {
1226 let repr = adt::represent_type(bcx.ccx(), ty);
1227 adt::trans_set_discr(bcx, &*repr, lldest, 0);
1234 bcx.tcx().sess.span_bug(ref_expr.span, &format!(
1235 "Non-DPS def {:?} referened by {}",
1236 def, bcx.node_id_to_string(ref_expr.id))[]);
1241 pub fn trans_def_fn_unadjusted<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>,
1242 ref_expr: &ast::Expr,
1244 param_substs: &subst::Substs<'tcx>)
1245 -> Datum<'tcx, Rvalue> {
1246 let _icx = push_ctxt("trans_def_datum_unadjusted");
1249 def::DefFn(did, _) |
1250 def::DefStruct(did) | def::DefVariant(_, did, _) |
1251 def::DefStaticMethod(did, def::FromImpl(_)) |
1252 def::DefMethod(did, _, def::FromImpl(_)) => {
1253 callee::trans_fn_ref(ccx, did, ExprId(ref_expr.id), param_substs)
1255 def::DefStaticMethod(impl_did, def::FromTrait(trait_did)) |
1256 def::DefMethod(impl_did, _, def::FromTrait(trait_did)) => {
1257 meth::trans_static_method_callee(ccx, impl_did,
1258 trait_did, ref_expr.id,
1262 ccx.tcx().sess.span_bug(ref_expr.span, &format!(
1263 "trans_def_fn_unadjusted invoked on: {:?} for {}",
1265 ref_expr.repr(ccx.tcx()))[]);
1270 /// Translates a reference to a local variable or argument. This always results in an lvalue datum.
1271 pub fn trans_local_var<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1273 -> Datum<'tcx, Lvalue> {
1274 let _icx = push_ctxt("trans_local_var");
1277 def::DefUpvar(nid, _, _) => {
1278 // Can't move upvars, so this is never a ZeroMemLastUse.
1279 let local_ty = node_id_type(bcx, nid);
1280 match bcx.fcx.llupvars.borrow().get(&nid) {
1281 Some(&val) => Datum::new(val, local_ty, Lvalue),
1283 bcx.sess().bug(&format!(
1284 "trans_local_var: no llval for upvar {} found",
1289 def::DefLocal(nid) => {
1290 let datum = match bcx.fcx.lllocals.borrow().get(&nid) {
1293 bcx.sess().bug(&format!(
1294 "trans_local_var: no datum for local/arg {} found",
1298 debug!("take_local(nid={}, v={}, ty={})",
1299 nid, bcx.val_to_string(datum.val), bcx.ty_to_string(datum.ty));
1303 bcx.sess().unimpl(&format!(
1304 "unsupported def type in trans_local_var: {:?}",
1310 /// Helper for enumerating the field types of structs, enums, or records. The optional node ID here
1311 /// is the node ID of the path identifying the enum variant in use. If none, this cannot possibly
1312 /// an enum variant (so, if it is and `node_id_opt` is none, this function panics).
1313 pub fn with_field_tys<'tcx, R, F>(tcx: &ty::ctxt<'tcx>,
1315 node_id_opt: Option<ast::NodeId>,
1318 F: FnOnce(ty::Disr, &[ty::field<'tcx>]) -> R,
1321 ty::ty_struct(did, substs) => {
1322 let fields = struct_fields(tcx, did, substs);
1323 let fields = monomorphize::normalize_associated_type(tcx, &fields);
1327 ty::ty_tup(ref v) => {
1328 op(0, &tup_fields(&v[])[])
1331 ty::ty_enum(_, substs) => {
1332 // We want the *variant* ID here, not the enum ID.
1335 tcx.sess.bug(&format!(
1336 "cannot get field types from the enum type {} \
1341 let def = tcx.def_map.borrow()[node_id].clone();
1343 def::DefVariant(enum_id, variant_id, _) => {
1344 let variant_info = ty::enum_variant_with_id(
1345 tcx, enum_id, variant_id);
1346 let fields = struct_fields(tcx, variant_id, substs);
1347 let fields = monomorphize::normalize_associated_type(tcx, &fields);
1348 op(variant_info.disr_val, &fields[])
1351 tcx.sess.bug("resolve didn't map this expr to a \
1360 tcx.sess.bug(&format!(
1361 "cannot get field types from the type {}",
1367 fn trans_struct<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1368 fields: &[ast::Field],
1369 base: Option<&ast::Expr>,
1370 expr_span: codemap::Span,
1371 expr_id: ast::NodeId,
1373 dest: Dest) -> Block<'blk, 'tcx> {
1374 let _icx = push_ctxt("trans_rec");
1376 let tcx = bcx.tcx();
1377 with_field_tys(tcx, ty, Some(expr_id), |discr, field_tys| {
1378 let mut need_base: Vec<bool> = repeat(true).take(field_tys.len()).collect();
1380 let numbered_fields = fields.iter().map(|field| {
1382 field_tys.iter().position(|field_ty|
1383 field_ty.name == field.ident.node.name);
1384 let result = match opt_pos {
1386 need_base[i] = false;
1390 tcx.sess.span_bug(field.span,
1391 "Couldn't find field in struct type")
1395 }).collect::<Vec<_>>();
1396 let optbase = match base {
1397 Some(base_expr) => {
1398 let mut leftovers = Vec::new();
1399 for (i, b) in need_base.iter().enumerate() {
1401 leftovers.push((i, field_tys[i].mt.ty));
1404 Some(StructBaseInfo {expr: base_expr,
1405 fields: leftovers })
1408 if need_base.iter().any(|b| *b) {
1409 tcx.sess.span_bug(expr_span, "missing fields and no base expr")
1418 numbered_fields.as_slice(),
1421 Some(NodeInfo { id: expr_id, span: expr_span }))
1425 /// Information that `trans_adt` needs in order to fill in the fields
1426 /// of a struct copied from a base struct (e.g., from an expression
1427 /// like `Foo { a: b, ..base }`.
1429 /// Note that `fields` may be empty; the base expression must always be
1430 /// evaluated for side-effects.
1431 pub struct StructBaseInfo<'a, 'tcx> {
1432 /// The base expression; will be evaluated after all explicit fields.
1433 expr: &'a ast::Expr,
1434 /// The indices of fields to copy paired with their types.
1435 fields: Vec<(uint, Ty<'tcx>)>
1438 /// Constructs an ADT instance:
1440 /// - `fields` should be a list of field indices paired with the
1441 /// expression to store into that field. The initializers will be
1442 /// evaluated in the order specified by `fields`.
1444 /// - `optbase` contains information on the base struct (if any) from
1445 /// which remaining fields are copied; see comments on `StructBaseInfo`.
1446 pub fn trans_adt<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1449 fields: &[(uint, &ast::Expr)],
1450 optbase: Option<StructBaseInfo<'a, 'tcx>>,
1452 source_location: Option<NodeInfo>)
1453 -> Block<'blk, 'tcx> {
1454 let _icx = push_ctxt("trans_adt");
1456 let repr = adt::represent_type(bcx.ccx(), ty);
1458 match source_location {
1459 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1465 // If we don't care about the result, just make a
1466 // temporary stack slot
1467 let addr = match dest {
1469 Ignore => alloc_ty(bcx, ty, "temp"),
1472 // This scope holds intermediates that must be cleaned should
1473 // panic occur before the ADT as a whole is ready.
1474 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1476 // First we trans the base, if we have one, to the dest
1477 for base in optbase.iter() {
1478 assert_eq!(discr, 0);
1480 match ty::expr_kind(bcx.tcx(), &*base.expr) {
1481 ty::RvalueDpsExpr | ty::RvalueDatumExpr if !type_needs_drop(bcx.tcx(), ty) => {
1482 bcx = trans_into(bcx, &*base.expr, SaveIn(addr));
1484 ty::RvalueStmtExpr => bcx.tcx().sess.bug("unexpected expr kind for struct base expr"),
1486 let base_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, &*base.expr, "base"));
1487 for &(i, t) in base.fields.iter() {
1488 let datum = base_datum.get_element(
1489 bcx, t, |srcval| adt::trans_field_ptr(bcx, &*repr, srcval, discr, i));
1490 assert!(type_is_sized(bcx.tcx(), datum.ty));
1491 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1492 bcx = datum.store_to(bcx, dest);
1498 match source_location {
1499 Some(src_loc) => debuginfo::set_source_location(bcx.fcx,
1505 if ty::type_is_simd(bcx.tcx(), ty) {
1506 // This is the constructor of a SIMD type, such types are
1507 // always primitive machine types and so do not have a
1508 // destructor or require any clean-up.
1509 let llty = type_of::type_of(bcx.ccx(), ty);
1511 // keep a vector as a register, and running through the field
1512 // `insertelement`ing them directly into that register
1513 // (i.e. avoid GEPi and `store`s to an alloca) .
1514 let mut vec_val = C_undef(llty);
1516 for &(i, ref e) in fields.iter() {
1517 let block_datum = trans(bcx, &**e);
1518 bcx = block_datum.bcx;
1519 let position = C_uint(bcx.ccx(), i);
1520 let value = block_datum.datum.to_llscalarish(bcx);
1521 vec_val = InsertElement(bcx, vec_val, value, position);
1523 Store(bcx, vec_val, addr);
1525 // Now, we just overwrite the fields we've explicitly specified
1526 for &(i, ref e) in fields.iter() {
1527 let dest = adt::trans_field_ptr(bcx, &*repr, addr, discr, i);
1528 let e_ty = expr_ty_adjusted(bcx, &**e);
1529 bcx = trans_into(bcx, &**e, SaveIn(dest));
1530 let scope = cleanup::CustomScope(custom_cleanup_scope);
1531 fcx.schedule_lifetime_end(scope, dest);
1532 fcx.schedule_drop_mem(scope, dest, e_ty);
1536 adt::trans_set_discr(bcx, &*repr, addr, discr);
1538 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1540 // If we don't care about the result drop the temporary we made
1544 bcx = glue::drop_ty(bcx, addr, ty, source_location);
1545 base::call_lifetime_end(bcx, addr);
1552 fn trans_immediate_lit<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1555 -> DatumBlock<'blk, 'tcx, Expr> {
1556 // must not be a string constant, that is a RvalueDpsExpr
1557 let _icx = push_ctxt("trans_immediate_lit");
1558 let ty = expr_ty(bcx, expr);
1559 let v = consts::const_lit(bcx.ccx(), expr, lit);
1560 immediate_rvalue_bcx(bcx, v, ty).to_expr_datumblock()
1563 fn trans_unary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1566 sub_expr: &ast::Expr)
1567 -> DatumBlock<'blk, 'tcx, Expr> {
1568 let ccx = bcx.ccx();
1570 let _icx = push_ctxt("trans_unary_datum");
1572 let method_call = MethodCall::expr(expr.id);
1574 // The only overloaded operator that is translated to a datum
1575 // is an overloaded deref, since it is always yields a `&T`.
1576 // Otherwise, we should be in the RvalueDpsExpr path.
1578 op == ast::UnDeref ||
1579 !ccx.tcx().method_map.borrow().contains_key(&method_call));
1581 let un_ty = expr_ty(bcx, expr);
1585 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1586 let llresult = Not(bcx, datum.to_llscalarish(bcx));
1587 immediate_rvalue_bcx(bcx, llresult, un_ty).to_expr_datumblock()
1590 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1591 let val = datum.to_llscalarish(bcx);
1593 if ty::type_is_fp(un_ty) {
1599 immediate_rvalue_bcx(bcx, llneg, un_ty).to_expr_datumblock()
1602 trans_uniq_expr(bcx, un_ty, sub_expr, expr_ty(bcx, sub_expr))
1605 let datum = unpack_datum!(bcx, trans(bcx, sub_expr));
1606 deref_once(bcx, expr, datum, method_call)
1611 fn trans_uniq_expr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1613 contents: &ast::Expr,
1614 contents_ty: Ty<'tcx>)
1615 -> DatumBlock<'blk, 'tcx, Expr> {
1616 let _icx = push_ctxt("trans_uniq_expr");
1618 assert!(type_is_sized(bcx.tcx(), contents_ty));
1619 let llty = type_of::type_of(bcx.ccx(), contents_ty);
1620 let size = llsize_of(bcx.ccx(), llty);
1621 let align = C_uint(bcx.ccx(), type_of::align_of(bcx.ccx(), contents_ty));
1622 let llty_ptr = llty.ptr_to();
1623 let Result { bcx, val } = malloc_raw_dyn(bcx, llty_ptr, box_ty, size, align);
1624 // Unique boxes do not allocate for zero-size types. The standard library
1625 // may assume that `free` is never called on the pointer returned for
1626 // `Box<ZeroSizeType>`.
1627 let bcx = if llsize_of_alloc(bcx.ccx(), llty) == 0 {
1628 trans_into(bcx, contents, SaveIn(val))
1630 let custom_cleanup_scope = fcx.push_custom_cleanup_scope();
1631 fcx.schedule_free_value(cleanup::CustomScope(custom_cleanup_scope),
1632 val, cleanup::HeapExchange, contents_ty);
1633 let bcx = trans_into(bcx, contents, SaveIn(val));
1634 fcx.pop_custom_cleanup_scope(custom_cleanup_scope);
1637 immediate_rvalue_bcx(bcx, val, box_ty).to_expr_datumblock()
1640 fn trans_addr_of<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1642 subexpr: &ast::Expr)
1643 -> DatumBlock<'blk, 'tcx, Expr> {
1644 let _icx = push_ctxt("trans_addr_of");
1646 let sub_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, subexpr, "addr_of"));
1647 match sub_datum.ty.sty {
1649 // Opened DST value, close to a fat pointer
1650 debug!("Closing fat pointer {}", bcx.ty_to_string(sub_datum.ty));
1652 let scratch = rvalue_scratch_datum(bcx,
1653 ty::close_type(bcx.tcx(), sub_datum.ty),
1655 let base = Load(bcx, get_dataptr(bcx, sub_datum.val));
1656 Store(bcx, base, get_dataptr(bcx, scratch.val));
1658 let len = Load(bcx, get_len(bcx, sub_datum.val));
1659 Store(bcx, len, get_len(bcx, scratch.val));
1661 DatumBlock::new(bcx, scratch.to_expr_datum())
1664 // Sized value, ref to a thin pointer
1665 let ty = expr_ty(bcx, expr);
1666 immediate_rvalue_bcx(bcx, sub_datum.val, ty).to_expr_datumblock()
1671 // Important to get types for both lhs and rhs, because one might be _|_
1672 // and the other not.
1673 fn trans_eager_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1674 binop_expr: &ast::Expr,
1681 -> DatumBlock<'blk, 'tcx, Expr> {
1682 let _icx = push_ctxt("trans_eager_binop");
1684 let tcx = bcx.tcx();
1685 let is_simd = ty::type_is_simd(tcx, lhs_t);
1687 if is_simd { ty::simd_type(tcx, lhs_t) }
1690 let is_float = ty::type_is_fp(intype);
1691 let is_signed = ty::type_is_signed(intype);
1693 let rhs = base::cast_shift_expr_rhs(bcx, op, lhs, rhs);
1696 let val = match op {
1698 if is_float { FAdd(bcx, lhs, rhs) }
1699 else { Add(bcx, lhs, rhs) }
1702 if is_float { FSub(bcx, lhs, rhs) }
1703 else { Sub(bcx, lhs, rhs) }
1706 if is_float { FMul(bcx, lhs, rhs) }
1707 else { Mul(bcx, lhs, rhs) }
1713 // Only zero-check integers; fp /0 is NaN
1714 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1715 op, lhs, rhs, rhs_t);
1727 // Only zero-check integers; fp %0 is NaN
1728 bcx = base::fail_if_zero_or_overflows(bcx, binop_expr.span,
1729 op, lhs, rhs, rhs_t);
1737 ast::BiBitOr => Or(bcx, lhs, rhs),
1738 ast::BiBitAnd => And(bcx, lhs, rhs),
1739 ast::BiBitXor => Xor(bcx, lhs, rhs),
1740 ast::BiShl => Shl(bcx, lhs, rhs),
1744 } else { LShr(bcx, lhs, rhs) }
1746 ast::BiEq | ast::BiNe | ast::BiLt | ast::BiGe | ast::BiLe | ast::BiGt => {
1747 if ty::type_is_scalar(rhs_t) {
1748 unpack_result!(bcx, base::compare_scalar_types(bcx, lhs, rhs, rhs_t, op))
1750 base::compare_simd_types(bcx, lhs, rhs, intype, ty::simd_size(tcx, lhs_t), op)
1752 bcx.tcx().sess.span_bug(binop_expr.span, "comparison operator unsupported for type")
1756 bcx.tcx().sess.span_bug(binop_expr.span, "unexpected binop");
1760 immediate_rvalue_bcx(bcx, val, binop_ty).to_expr_datumblock()
1763 // refinement types would obviate the need for this
1764 enum lazy_binop_ty {
1769 fn trans_lazy_binop<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1770 binop_expr: &ast::Expr,
1774 -> DatumBlock<'blk, 'tcx, Expr> {
1775 let _icx = push_ctxt("trans_lazy_binop");
1776 let binop_ty = expr_ty(bcx, binop_expr);
1779 let DatumBlock {bcx: past_lhs, datum: lhs} = trans(bcx, a);
1780 let lhs = lhs.to_llscalarish(past_lhs);
1782 if past_lhs.unreachable.get() {
1783 return immediate_rvalue_bcx(past_lhs, lhs, binop_ty).to_expr_datumblock();
1786 let join = fcx.new_id_block("join", binop_expr.id);
1787 let before_rhs = fcx.new_id_block("before_rhs", b.id);
1790 lazy_and => CondBr(past_lhs, lhs, before_rhs.llbb, join.llbb),
1791 lazy_or => CondBr(past_lhs, lhs, join.llbb, before_rhs.llbb)
1794 let DatumBlock {bcx: past_rhs, datum: rhs} = trans(before_rhs, b);
1795 let rhs = rhs.to_llscalarish(past_rhs);
1797 if past_rhs.unreachable.get() {
1798 return immediate_rvalue_bcx(join, lhs, binop_ty).to_expr_datumblock();
1801 Br(past_rhs, join.llbb);
1802 let phi = Phi(join, Type::i1(bcx.ccx()), &[lhs, rhs],
1803 &[past_lhs.llbb, past_rhs.llbb]);
1805 return immediate_rvalue_bcx(join, phi, binop_ty).to_expr_datumblock();
1808 fn trans_binary<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1813 -> DatumBlock<'blk, 'tcx, Expr> {
1814 let _icx = push_ctxt("trans_binary");
1815 let ccx = bcx.ccx();
1817 // if overloaded, would be RvalueDpsExpr
1818 assert!(!ccx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
1822 trans_lazy_binop(bcx, expr, lazy_and, lhs, rhs)
1825 trans_lazy_binop(bcx, expr, lazy_or, lhs, rhs)
1829 let lhs_datum = unpack_datum!(bcx, trans(bcx, lhs));
1830 let rhs_datum = unpack_datum!(bcx, trans(bcx, rhs));
1831 let binop_ty = expr_ty(bcx, expr);
1833 debug!("trans_binary (expr {}): lhs_datum={}",
1835 lhs_datum.to_string(ccx));
1836 let lhs_ty = lhs_datum.ty;
1837 let lhs = lhs_datum.to_llscalarish(bcx);
1839 debug!("trans_binary (expr {}): rhs_datum={}",
1841 rhs_datum.to_string(ccx));
1842 let rhs_ty = rhs_datum.ty;
1843 let rhs = rhs_datum.to_llscalarish(bcx);
1844 trans_eager_binop(bcx, expr, binop_ty, op,
1845 lhs_ty, lhs, rhs_ty, rhs)
1850 fn trans_overloaded_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1852 method_call: MethodCall,
1853 lhs: Datum<'tcx, Expr>,
1854 rhs: Vec<(Datum<'tcx, Expr>, ast::NodeId)>,
1857 -> Result<'blk, 'tcx> {
1858 let method_ty = (*bcx.tcx().method_map.borrow())[method_call].ty;
1859 callee::trans_call_inner(bcx,
1860 Some(expr_info(expr)),
1861 monomorphize_type(bcx, method_ty),
1862 |bcx, arg_cleanup_scope| {
1863 meth::trans_method_callee(bcx,
1868 callee::ArgOverloadedOp(lhs, rhs, autoref),
1872 fn trans_overloaded_call<'a, 'blk, 'tcx>(mut bcx: Block<'blk, 'tcx>,
1874 callee: &'a ast::Expr,
1875 args: &'a [P<ast::Expr>],
1877 -> Block<'blk, 'tcx> {
1878 let method_call = MethodCall::expr(expr.id);
1879 let method_type = (*bcx.tcx()
1881 .borrow())[method_call]
1883 let mut all_args = vec!(callee);
1884 all_args.extend(args.iter().map(|e| &**e));
1886 callee::trans_call_inner(bcx,
1887 Some(expr_info(expr)),
1888 monomorphize_type(bcx,
1890 |bcx, arg_cleanup_scope| {
1891 meth::trans_method_callee(
1897 callee::ArgOverloadedCall(all_args),
1902 fn int_cast(bcx: Block,
1908 let _icx = push_ctxt("int_cast");
1910 let srcsz = llvm::LLVMGetIntTypeWidth(llsrctype.to_ref());
1911 let dstsz = llvm::LLVMGetIntTypeWidth(lldsttype.to_ref());
1912 return if dstsz == srcsz {
1913 BitCast(bcx, llsrc, lldsttype)
1914 } else if srcsz > dstsz {
1915 TruncOrBitCast(bcx, llsrc, lldsttype)
1917 SExtOrBitCast(bcx, llsrc, lldsttype)
1919 ZExtOrBitCast(bcx, llsrc, lldsttype)
1924 fn float_cast(bcx: Block,
1929 let _icx = push_ctxt("float_cast");
1930 let srcsz = llsrctype.float_width();
1931 let dstsz = lldsttype.float_width();
1932 return if dstsz > srcsz {
1933 FPExt(bcx, llsrc, lldsttype)
1934 } else if srcsz > dstsz {
1935 FPTrunc(bcx, llsrc, lldsttype)
1939 #[derive(Copy, PartialEq, Show)]
1940 pub enum cast_kind {
1948 pub fn cast_type_kind<'tcx>(tcx: &ty::ctxt<'tcx>, t: Ty<'tcx>) -> cast_kind {
1950 ty::ty_char => cast_integral,
1951 ty::ty_float(..) => cast_float,
1952 ty::ty_rptr(_, mt) | ty::ty_ptr(mt) => {
1953 if type_is_sized(tcx, mt.ty) {
1959 ty::ty_bare_fn(..) => cast_pointer,
1960 ty::ty_int(..) => cast_integral,
1961 ty::ty_uint(..) => cast_integral,
1962 ty::ty_bool => cast_integral,
1963 ty::ty_enum(..) => cast_enum,
1968 fn cast_is_noop<'tcx>(t_in: Ty<'tcx>, t_out: Ty<'tcx>) -> bool {
1969 match (ty::deref(t_in, true), ty::deref(t_out, true)) {
1970 (Some(ty::mt{ ty: t_in, .. }), Some(ty::mt{ ty: t_out, .. })) => {
1977 fn trans_imm_cast<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
1980 -> DatumBlock<'blk, 'tcx, Expr> {
1981 let _icx = push_ctxt("trans_cast");
1983 let ccx = bcx.ccx();
1985 let t_in = expr_ty(bcx, expr);
1986 let t_out = node_id_type(bcx, id);
1987 let k_in = cast_type_kind(bcx.tcx(), t_in);
1988 let k_out = cast_type_kind(bcx.tcx(), t_out);
1989 let s_in = k_in == cast_integral && ty::type_is_signed(t_in);
1990 let ll_t_in = type_of::arg_type_of(ccx, t_in);
1991 let ll_t_out = type_of::arg_type_of(ccx, t_out);
1993 // Convert the value to be cast into a ValueRef, either by-ref or
1994 // by-value as appropriate given its type:
1995 let mut datum = unpack_datum!(bcx, trans(bcx, expr));
1997 if cast_is_noop(datum.ty, t_out) {
1999 return DatumBlock::new(bcx, datum);
2002 let newval = match (k_in, k_out) {
2003 (cast_integral, cast_integral) => {
2004 let llexpr = datum.to_llscalarish(bcx);
2005 int_cast(bcx, ll_t_out, ll_t_in, llexpr, s_in)
2007 (cast_float, cast_float) => {
2008 let llexpr = datum.to_llscalarish(bcx);
2009 float_cast(bcx, ll_t_out, ll_t_in, llexpr)
2011 (cast_integral, cast_float) => {
2012 let llexpr = datum.to_llscalarish(bcx);
2014 SIToFP(bcx, llexpr, ll_t_out)
2015 } else { UIToFP(bcx, llexpr, ll_t_out) }
2017 (cast_float, cast_integral) => {
2018 let llexpr = datum.to_llscalarish(bcx);
2019 if ty::type_is_signed(t_out) {
2020 FPToSI(bcx, llexpr, ll_t_out)
2021 } else { FPToUI(bcx, llexpr, ll_t_out) }
2023 (cast_integral, cast_pointer) => {
2024 let llexpr = datum.to_llscalarish(bcx);
2025 IntToPtr(bcx, llexpr, ll_t_out)
2027 (cast_pointer, cast_integral) => {
2028 let llexpr = datum.to_llscalarish(bcx);
2029 PtrToInt(bcx, llexpr, ll_t_out)
2031 (cast_pointer, cast_pointer) => {
2032 let llexpr = datum.to_llscalarish(bcx);
2033 PointerCast(bcx, llexpr, ll_t_out)
2035 (cast_enum, cast_integral) |
2036 (cast_enum, cast_float) => {
2038 let repr = adt::represent_type(ccx, t_in);
2039 let datum = unpack_datum!(
2040 bcx, datum.to_lvalue_datum(bcx, "trans_imm_cast", expr.id));
2041 let llexpr_ptr = datum.to_llref();
2043 adt::trans_get_discr(bcx, &*repr, llexpr_ptr, Some(Type::i64(ccx)));
2045 cast_integral => int_cast(bcx, ll_t_out,
2046 val_ty(lldiscrim_a),
2048 cast_float => SIToFP(bcx, lldiscrim_a, ll_t_out),
2050 ccx.sess().bug(&format!("translating unsupported cast: \
2051 {} ({:?}) -> {} ({:?})",
2052 t_in.repr(bcx.tcx()),
2054 t_out.repr(bcx.tcx()),
2059 _ => ccx.sess().bug(&format!("translating unsupported cast: \
2060 {} ({:?}) -> {} ({:?})",
2061 t_in.repr(bcx.tcx()),
2063 t_out.repr(bcx.tcx()),
2066 return immediate_rvalue_bcx(bcx, newval, t_out).to_expr_datumblock();
2069 fn trans_assign_op<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2074 -> Block<'blk, 'tcx> {
2075 let _icx = push_ctxt("trans_assign_op");
2078 debug!("trans_assign_op(expr={})", bcx.expr_to_string(expr));
2080 // User-defined operator methods cannot be used with `+=` etc right now
2081 assert!(!bcx.tcx().method_map.borrow().contains_key(&MethodCall::expr(expr.id)));
2083 // Evaluate LHS (destination), which should be an lvalue
2084 let dst_datum = unpack_datum!(bcx, trans_to_lvalue(bcx, dst, "assign_op"));
2085 assert!(!type_needs_drop(bcx.tcx(), dst_datum.ty));
2086 let dst_ty = dst_datum.ty;
2087 let dst = load_ty(bcx, dst_datum.val, dst_datum.ty);
2090 let rhs_datum = unpack_datum!(bcx, trans(bcx, &*src));
2091 let rhs_ty = rhs_datum.ty;
2092 let rhs = rhs_datum.to_llscalarish(bcx);
2094 // Perform computation and store the result
2095 let result_datum = unpack_datum!(
2096 bcx, trans_eager_binop(bcx, expr, dst_datum.ty, op,
2097 dst_ty, dst, rhs_ty, rhs));
2098 return result_datum.store_to(bcx, dst_datum.val);
2101 fn auto_ref<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2102 datum: Datum<'tcx, Expr>,
2104 -> DatumBlock<'blk, 'tcx, Expr> {
2107 // Ensure cleanup of `datum` if not already scheduled and obtain
2108 // a "by ref" pointer.
2109 let lv_datum = unpack_datum!(bcx, datum.to_lvalue_datum(bcx, "autoref", expr.id));
2111 // Compute final type. Note that we are loose with the region and
2112 // mutability, since those things don't matter in trans.
2113 let referent_ty = lv_datum.ty;
2114 let ptr_ty = ty::mk_imm_rptr(bcx.tcx(), bcx.tcx().mk_region(ty::ReStatic), referent_ty);
2117 let llref = lv_datum.to_llref();
2119 // Construct the resulting datum, using what was the "by ref"
2120 // ValueRef of type `referent_ty` to be the "by value" ValueRef
2121 // of type `&referent_ty`.
2122 DatumBlock::new(bcx, Datum::new(llref, ptr_ty, RvalueExpr(Rvalue::new(ByValue))))
2125 fn deref_multiple<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2127 datum: Datum<'tcx, Expr>,
2129 -> DatumBlock<'blk, 'tcx, Expr> {
2131 let mut datum = datum;
2132 for i in range(0, times) {
2133 let method_call = MethodCall::autoderef(expr.id, i);
2134 datum = unpack_datum!(bcx, deref_once(bcx, expr, datum, method_call));
2136 DatumBlock { bcx: bcx, datum: datum }
2139 fn deref_once<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2141 datum: Datum<'tcx, Expr>,
2142 method_call: MethodCall)
2143 -> DatumBlock<'blk, 'tcx, Expr> {
2144 let ccx = bcx.ccx();
2146 debug!("deref_once(expr={}, datum={}, method_call={:?})",
2147 expr.repr(bcx.tcx()),
2148 datum.to_string(ccx),
2153 // Check for overloaded deref.
2154 let method_ty = ccx.tcx().method_map.borrow()
2155 .get(&method_call).map(|method| method.ty);
2156 let datum = match method_ty {
2157 Some(method_ty) => {
2158 let method_ty = monomorphize_type(bcx, method_ty);
2160 // Overloaded. Evaluate `trans_overloaded_op`, which will
2161 // invoke the user's deref() method, which basically
2162 // converts from the `Smaht<T>` pointer that we have into
2163 // a `&T` pointer. We can then proceed down the normal
2164 // path (below) to dereference that `&T`.
2165 let datum = match method_call.adjustment {
2166 // Always perform an AutoPtr when applying an overloaded auto-deref
2167 ty::AutoDeref(_) => unpack_datum!(bcx, auto_ref(bcx, datum, expr)),
2171 let ref_ty = // invoked methods have their LB regions instantiated
2172 ty::assert_no_late_bound_regions(
2173 ccx.tcx(), &ty::ty_fn_ret(method_ty)).unwrap();
2174 let scratch = rvalue_scratch_datum(bcx, ref_ty, "overloaded_deref");
2176 unpack_result!(bcx, trans_overloaded_op(bcx, expr, method_call,
2177 datum, Vec::new(), Some(SaveIn(scratch.val)),
2179 scratch.to_expr_datum()
2182 // Not overloaded. We already have a pointer we know how to deref.
2187 let r = match datum.ty.sty {
2188 ty::ty_uniq(content_ty) => {
2189 if type_is_sized(bcx.tcx(), content_ty) {
2190 deref_owned_pointer(bcx, expr, datum, content_ty)
2192 // A fat pointer and an opened DST value have the same
2193 // representation just different types. Since there is no
2194 // temporary for `*e` here (because it is unsized), we cannot
2195 // emulate the sized object code path for running drop glue and
2196 // free. Instead, we schedule cleanup for `e`, turning it into
2198 let datum = unpack_datum!(
2199 bcx, datum.to_lvalue_datum(bcx, "deref", expr.id));
2201 let datum = Datum::new(datum.val, ty::mk_open(bcx.tcx(), content_ty), LvalueExpr);
2202 DatumBlock::new(bcx, datum)
2206 ty::ty_ptr(ty::mt { ty: content_ty, .. }) |
2207 ty::ty_rptr(_, ty::mt { ty: content_ty, .. }) => {
2208 if type_is_sized(bcx.tcx(), content_ty) {
2209 let ptr = datum.to_llscalarish(bcx);
2211 // Always generate an lvalue datum, even if datum.mode is
2212 // an rvalue. This is because datum.mode is only an
2213 // rvalue for non-owning pointers like &T or *T, in which
2214 // case cleanup *is* scheduled elsewhere, by the true
2215 // owner (or, in the case of *T, by the user).
2216 DatumBlock::new(bcx, Datum::new(ptr, content_ty, LvalueExpr))
2218 // A fat pointer and an opened DST value have the same representation
2219 // just different types.
2220 DatumBlock::new(bcx, Datum::new(datum.val,
2221 ty::mk_open(bcx.tcx(), content_ty),
2227 bcx.tcx().sess.span_bug(
2229 &format!("deref invoked on expr of illegal type {}",
2230 datum.ty.repr(bcx.tcx()))[]);
2234 debug!("deref_once(expr={}, method_call={:?}, result={})",
2235 expr.id, method_call, r.datum.to_string(ccx));
2239 /// We microoptimize derefs of owned pointers a bit here. Basically, the idea is to make the
2240 /// deref of an rvalue result in an rvalue. This helps to avoid intermediate stack slots in the
2241 /// resulting LLVM. The idea here is that, if the `Box<T>` pointer is an rvalue, then we can
2242 /// schedule a *shallow* free of the `Box<T>` pointer, and then return a ByRef rvalue into the
2243 /// pointer. Because the free is shallow, it is legit to return an rvalue, because we know that
2244 /// the contents are not yet scheduled to be freed. The language rules ensure that the contents
2245 /// will be used (or moved) before the free occurs.
2246 fn deref_owned_pointer<'blk, 'tcx>(bcx: Block<'blk, 'tcx>,
2248 datum: Datum<'tcx, Expr>,
2249 content_ty: Ty<'tcx>)
2250 -> DatumBlock<'blk, 'tcx, Expr> {
2252 RvalueExpr(Rvalue { mode: ByRef }) => {
2253 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2254 let ptr = Load(bcx, datum.val);
2255 if !type_is_zero_size(bcx.ccx(), content_ty) {
2256 bcx.fcx.schedule_free_value(scope, ptr, cleanup::HeapExchange, content_ty);
2259 RvalueExpr(Rvalue { mode: ByValue }) => {
2260 let scope = cleanup::temporary_scope(bcx.tcx(), expr.id);
2261 if !type_is_zero_size(bcx.ccx(), content_ty) {
2262 bcx.fcx.schedule_free_value(scope, datum.val, cleanup::HeapExchange,
2269 // If we had an rvalue in, we produce an rvalue out.
2270 let (llptr, kind) = match datum.kind {
2272 (Load(bcx, datum.val), LvalueExpr)
2274 RvalueExpr(Rvalue { mode: ByRef }) => {
2275 (Load(bcx, datum.val), RvalueExpr(Rvalue::new(ByRef)))
2277 RvalueExpr(Rvalue { mode: ByValue }) => {
2278 (datum.val, RvalueExpr(Rvalue::new(ByRef)))
2282 let datum = Datum { ty: content_ty, val: llptr, kind: kind };
2283 DatumBlock { bcx: bcx, datum: datum }