/
callee.rs
908 lines (807 loc) · 33.6 KB
/
callee.rs
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.
/*!
* Handles translation of callees as well as other call-related
* things. Callees are a superset of normal rust values and sometimes
* have different representations. In particular, top-level fn items
* and methods are represented as just a fn ptr and not a full
* closure.
*/
use back::abi;
use driver::session;
use lib::llvm::{ValueRef, NoAliasAttribute, StructRetAttribute, NoCaptureAttribute};
use lib::llvm::llvm;
use metadata::csearch;
use middle::trans::base;
use middle::trans::base::*;
use middle::trans::build::*;
use middle::trans::callee;
use middle::trans::cleanup;
use middle::trans::cleanup::CleanupMethods;
use middle::trans::common;
use middle::trans::common::*;
use middle::trans::datum::*;
use middle::trans::datum::Datum;
use middle::trans::expr;
use middle::trans::glue;
use middle::trans::inline;
use middle::trans::meth;
use middle::trans::monomorphize;
use middle::trans::type_of;
use middle::trans::foreign;
use middle::ty;
use middle::subst::Subst;
use middle::typeck;
use middle::typeck::coherence::make_substs_for_receiver_types;
use middle::typeck::MethodCall;
use util::ppaux::Repr;
use middle::trans::type_::Type;
use syntax::ast;
use synabi = syntax::abi;
use syntax::ast_map;
pub struct MethodData {
pub llfn: ValueRef,
pub llself: ValueRef,
}
pub enum CalleeData {
Closure(Datum<Lvalue>),
// Represents a (possibly monomorphized) top-level fn item or method
// item. Note that this is just the fn-ptr and is not a Rust closure
// value (which is a pair).
Fn(/* llfn */ ValueRef),
TraitMethod(MethodData)
}
pub struct Callee<'a> {
pub bcx: &'a Block<'a>,
pub data: CalleeData
}
fn trans<'a>(bcx: &'a Block<'a>, expr: &ast::Expr) -> Callee<'a> {
let _icx = push_ctxt("trans_callee");
debug!("callee::trans(expr={})", expr.repr(bcx.tcx()));
// pick out special kinds of expressions that can be called:
match expr.node {
ast::ExprPath(_) => {
return trans_def(bcx, bcx.def(expr.id), expr);
}
_ => {}
}
// any other expressions are closures:
return datum_callee(bcx, expr);
fn datum_callee<'a>(bcx: &'a Block<'a>, expr: &ast::Expr) -> Callee<'a> {
let DatumBlock {bcx: mut bcx, datum} = expr::trans(bcx, expr);
match ty::get(datum.ty).sty {
ty::ty_bare_fn(..) => {
let llval = datum.to_llscalarish(bcx);
return Callee {bcx: bcx, data: Fn(llval)};
}
ty::ty_closure(..) => {
let datum = unpack_datum!(
bcx, datum.to_lvalue_datum(bcx, "callee", expr.id));
return Callee {bcx: bcx, data: Closure(datum)};
}
_ => {
bcx.tcx().sess.span_bug(
expr.span,
format!("type of callee is neither bare-fn nor closure: {}",
bcx.ty_to_str(datum.ty)));
}
}
}
fn fn_callee<'a>(bcx: &'a Block<'a>, llfn: ValueRef) -> Callee<'a> {
return Callee {bcx: bcx, data: Fn(llfn)};
}
fn trans_def<'a>(bcx: &'a Block<'a>, def: ast::Def, ref_expr: &ast::Expr)
-> Callee<'a> {
match def {
ast::DefFn(did, _) |
ast::DefStaticMethod(did, ast::FromImpl(_), _) => {
fn_callee(bcx, trans_fn_ref(bcx, did, ExprId(ref_expr.id)))
}
ast::DefStaticMethod(impl_did,
ast::FromTrait(trait_did),
_) => {
fn_callee(bcx, meth::trans_static_method_callee(bcx, impl_did,
trait_did,
ref_expr.id))
}
ast::DefVariant(tid, vid, _) => {
// nullary variants are not callable
assert!(ty::enum_variant_with_id(bcx.tcx(),
tid,
vid).args.len() > 0u);
fn_callee(bcx, trans_fn_ref(bcx, vid, ExprId(ref_expr.id)))
}
ast::DefStruct(def_id) => {
fn_callee(bcx, trans_fn_ref(bcx, def_id, ExprId(ref_expr.id)))
}
ast::DefStatic(..) |
ast::DefArg(..) |
ast::DefLocal(..) |
ast::DefBinding(..) |
ast::DefUpvar(..) => {
datum_callee(bcx, ref_expr)
}
ast::DefMod(..) | ast::DefForeignMod(..) | ast::DefTrait(..) |
ast::DefTy(..) | ast::DefPrimTy(..) |
ast::DefUse(..) | ast::DefTyParamBinder(..) |
ast::DefRegion(..) | ast::DefLabel(..) | ast::DefTyParam(..) |
ast::DefSelfTy(..) | ast::DefMethod(..) => {
bcx.tcx().sess.span_bug(
ref_expr.span,
format!("cannot translate def {:?} \
to a callable thing!", def));
}
}
}
}
pub fn trans_fn_ref(bcx: &Block, def_id: ast::DefId, node: ExprOrMethodCall) -> ValueRef {
/*!
*
* Translates a reference (with id `ref_id`) to the fn/method
* with id `def_id` into a function pointer. This may require
* monomorphization or inlining. */
let _icx = push_ctxt("trans_fn_ref");
let type_params = node_id_type_params(bcx, node);
let vtable_key = match node {
ExprId(id) => MethodCall::expr(id),
MethodCall(method_call) => method_call
};
let vtables = node_vtables(bcx, vtable_key);
debug!("trans_fn_ref(def_id={}, node={:?}, type_params={}, vtables={})",
def_id.repr(bcx.tcx()), node, type_params.repr(bcx.tcx()),
vtables.repr(bcx.tcx()));
trans_fn_ref_with_vtables(bcx, def_id, node,
type_params,
vtables)
}
fn trans_fn_ref_with_vtables_to_callee<'a>(bcx: &'a Block<'a>,
def_id: ast::DefId,
ref_id: ast::NodeId,
type_params: Vec<ty::t>,
vtables: Option<typeck::vtable_res>)
-> Callee<'a> {
Callee {bcx: bcx,
data: Fn(trans_fn_ref_with_vtables(bcx, def_id, ExprId(ref_id),
type_params, vtables))}
}
fn resolve_default_method_vtables(bcx: &Block,
impl_id: ast::DefId,
method: &ty::Method,
substs: &ty::substs,
impl_vtables: Option<typeck::vtable_res>)
-> (typeck::vtable_res, typeck::vtable_param_res) {
// Get the vtables that the impl implements the trait at
let impl_res = ty::lookup_impl_vtables(bcx.tcx(), impl_id);
// Build up a param_substs that we are going to resolve the
// trait_vtables under.
let param_substs = param_substs {
tys: substs.tps.clone(),
self_ty: substs.self_ty,
vtables: impl_vtables.clone(),
self_vtables: None
};
let mut param_vtables = resolve_vtables_under_param_substs(
bcx.tcx(), Some(¶m_substs), impl_res.trait_vtables.as_slice());
// Now we pull any vtables for parameters on the actual method.
let num_method_vtables = method.generics.type_param_defs().len();
match impl_vtables {
Some(ref vtables) => {
let num_impl_type_parameters =
vtables.len() - num_method_vtables;
param_vtables.push_all(vtables.tailn(num_impl_type_parameters))
},
None => {
param_vtables.extend(range(0, num_method_vtables).map(
|_| -> typeck::vtable_param_res {
Vec::new()
}
))
}
}
let self_vtables = resolve_param_vtables_under_param_substs(
bcx.tcx(), Some(¶m_substs), impl_res.self_vtables.as_slice());
(param_vtables, self_vtables)
}
pub fn trans_fn_ref_with_vtables(
bcx: &Block, //
def_id: ast::DefId, // def id of fn
node: ExprOrMethodCall, // node id of use of fn; may be zero if N/A
type_params: Vec<ty::t>, // values for fn's ty params
vtables: Option<typeck::vtable_res>) // vtables for the call
-> ValueRef {
/*!
* Translates a reference to a fn/method item, monomorphizing and
* inlining as it goes.
*
* # Parameters
*
* - `bcx`: the current block where the reference to the fn occurs
* - `def_id`: def id of the fn or method item being referenced
* - `node`: node id of the reference to the fn/method, if applicable.
* This parameter may be zero; but, if so, the resulting value may not
* have the right type, so it must be cast before being used.
* - `type_params`: values for each of the fn/method's type parameters
* - `vtables`: values for each bound on each of the type parameters
*/
let _icx = push_ctxt("trans_fn_ref_with_vtables");
let ccx = bcx.ccx();
let tcx = bcx.tcx();
debug!("trans_fn_ref_with_vtables(bcx={}, def_id={}, node={:?}, \
type_params={}, vtables={})",
bcx.to_str(),
def_id.repr(tcx),
node,
type_params.repr(tcx),
vtables.repr(tcx));
assert!(type_params.iter().all(|t| !ty::type_needs_infer(*t)));
// Polytype of the function item (may have type params)
let fn_tpt = ty::lookup_item_type(tcx, def_id);
let substs = ty::substs {
regions: ty::ErasedRegions,
self_ty: None,
tps: type_params
};
// Load the info for the appropriate trait if necessary.
match ty::trait_of_method(tcx, def_id) {
None => {}
Some(trait_id) => {
ty::populate_implementations_for_trait_if_necessary(tcx, trait_id)
}
}
// We need to do a bunch of special handling for default methods.
// We need to modify the def_id and our substs in order to monomorphize
// the function.
let (is_default, def_id, substs, self_vtables, vtables) =
match ty::provided_source(tcx, def_id) {
None => (false, def_id, substs, None, vtables),
Some(source_id) => {
// There are two relevant substitutions when compiling
// default methods. First, there is the substitution for
// the type parameters of the impl we are using and the
// method we are calling. This substitution is the substs
// argument we already have.
// In order to compile a default method, though, we need
// to consider another substitution: the substitution for
// the type parameters on trait; the impl we are using
// implements the trait at some particular type
// parameters, and we need to substitute for those first.
// So, what we need to do is find this substitution and
// compose it with the one we already have.
let impl_id = ty::method(tcx, def_id).container_id();
let method = ty::method(tcx, source_id);
let trait_ref = ty::impl_trait_ref(tcx, impl_id)
.expect("could not find trait_ref for impl with \
default methods");
// Compute the first substitution
let first_subst = make_substs_for_receiver_types(
tcx, impl_id, &*trait_ref, &*method);
// And compose them
let new_substs = first_subst.subst(tcx, &substs);
debug!("trans_fn_with_vtables - default method: \
substs = {}, trait_subst = {}, \
first_subst = {}, new_subst = {}, \
vtables = {}",
substs.repr(tcx), trait_ref.substs.repr(tcx),
first_subst.repr(tcx), new_substs.repr(tcx),
vtables.repr(tcx));
let (param_vtables, self_vtables) =
resolve_default_method_vtables(bcx, impl_id,
&*method, &substs, vtables);
debug!("trans_fn_with_vtables - default method: \
self_vtable = {}, param_vtables = {}",
self_vtables.repr(tcx), param_vtables.repr(tcx));
(true, source_id,
new_substs, Some(self_vtables), Some(param_vtables))
}
};
// Check whether this fn has an inlined copy and, if so, redirect
// def_id to the local id of the inlined copy.
let def_id = {
if def_id.krate != ast::LOCAL_CRATE {
inline::maybe_instantiate_inline(ccx, def_id)
} else {
def_id
}
};
// We must monomorphise if the fn has type parameters, is a rust
// intrinsic, or is a default method. In particular, if we see an
// intrinsic that is inlined from a different crate, we want to reemit the
// intrinsic instead of trying to call it in the other crate.
let must_monomorphise = if substs.tps.len() > 0 || is_default {
true
} else if def_id.krate == ast::LOCAL_CRATE {
let map_node = session::expect(
ccx.sess(),
tcx.map.find(def_id.node),
|| format!("local item should be in ast map"));
match map_node {
ast_map::NodeForeignItem(_) => {
tcx.map.get_foreign_abi(def_id.node) == synabi::RustIntrinsic
}
_ => false
}
} else {
false
};
// Create a monomorphic version of generic functions
if must_monomorphise {
// Should be either intra-crate or inlined.
assert_eq!(def_id.krate, ast::LOCAL_CRATE);
let opt_ref_id = match node {
ExprId(id) => if id != 0 { Some(id) } else { None },
MethodCall(_) => None,
};
let (val, must_cast) =
monomorphize::monomorphic_fn(ccx, def_id, &substs,
vtables, self_vtables,
opt_ref_id);
let mut val = val;
if must_cast && node != ExprId(0) {
// Monotype of the REFERENCE to the function (type params
// are subst'd)
let ref_ty = match node {
ExprId(id) => node_id_type(bcx, id),
MethodCall(method_call) => {
let t = bcx.tcx().method_map.borrow().get(&method_call).ty;
monomorphize_type(bcx, t)
}
};
val = PointerCast(
bcx, val, type_of::type_of_fn_from_ty(ccx, ref_ty).ptr_to());
}
return val;
}
// Find the actual function pointer.
let mut val = {
if def_id.krate == ast::LOCAL_CRATE {
// Internal reference.
get_item_val(ccx, def_id.node)
} else {
// External reference.
trans_external_path(ccx, def_id, fn_tpt.ty)
}
};
// This is subtle and surprising, but sometimes we have to bitcast
// the resulting fn pointer. The reason has to do with external
// functions. If you have two crates that both bind the same C
// library, they may not use precisely the same types: for
// example, they will probably each declare their own structs,
// which are distinct types from LLVM's point of view (nominal
// types).
//
// Now, if those two crates are linked into an application, and
// they contain inlined code, you can wind up with a situation
// where both of those functions wind up being loaded into this
// application simultaneously. In that case, the same function
// (from LLVM's point of view) requires two types. But of course
// LLVM won't allow one function to have two types.
//
// What we currently do, therefore, is declare the function with
// one of the two types (whichever happens to come first) and then
// bitcast as needed when the function is referenced to make sure
// it has the type we expect.
//
// This can occur on either a crate-local or crate-external
// reference. It also occurs when testing libcore and in some
// other weird situations. Annoying.
let llty = type_of::type_of_fn_from_ty(ccx, fn_tpt.ty);
let llptrty = llty.ptr_to();
if val_ty(val) != llptrty {
val = BitCast(bcx, val, llptrty);
}
val
}
// ______________________________________________________________________
// Translating calls
pub fn trans_call<'a>(
in_cx: &'a Block<'a>,
call_ex: &ast::Expr,
f: &ast::Expr,
args: CallArgs,
dest: expr::Dest)
-> &'a Block<'a> {
let _icx = push_ctxt("trans_call");
trans_call_inner(in_cx,
Some(common::expr_info(call_ex)),
expr_ty(in_cx, f),
|cx, _| trans(cx, f),
args,
Some(dest)).bcx
}
pub fn trans_method_call<'a>(
bcx: &'a Block<'a>,
call_ex: &ast::Expr,
rcvr: &ast::Expr,
args: CallArgs,
dest: expr::Dest)
-> &'a Block<'a> {
let _icx = push_ctxt("trans_method_call");
debug!("trans_method_call(call_ex={})", call_ex.repr(bcx.tcx()));
let method_call = MethodCall::expr(call_ex.id);
let method_ty = bcx.tcx().method_map.borrow().get(&method_call).ty;
trans_call_inner(
bcx,
Some(common::expr_info(call_ex)),
monomorphize_type(bcx, method_ty),
|cx, arg_cleanup_scope| {
meth::trans_method_callee(cx, method_call, Some(rcvr), arg_cleanup_scope)
},
args,
Some(dest)).bcx
}
pub fn trans_lang_call<'a>(
bcx: &'a Block<'a>,
did: ast::DefId,
args: &[ValueRef],
dest: Option<expr::Dest>)
-> Result<'a> {
let fty = if did.krate == ast::LOCAL_CRATE {
ty::node_id_to_type(bcx.tcx(), did.node)
} else {
csearch::get_type(bcx.tcx(), did).ty
};
callee::trans_call_inner(bcx,
None,
fty,
|bcx, _| {
trans_fn_ref_with_vtables_to_callee(bcx,
did,
0,
vec!(),
None)
},
ArgVals(args),
dest)
}
pub fn trans_call_inner<'a>(
bcx: &'a Block<'a>,
call_info: Option<NodeInfo>,
callee_ty: ty::t,
get_callee: |bcx: &'a Block<'a>,
arg_cleanup_scope: cleanup::ScopeId|
-> Callee<'a>,
args: CallArgs,
dest: Option<expr::Dest>)
-> Result<'a> {
/*!
* This behemoth of a function translates function calls.
* Unfortunately, in order to generate more efficient LLVM
* output at -O0, it has quite a complex signature (refactoring
* this into two functions seems like a good idea).
*
* In particular, for lang items, it is invoked with a dest of
* None, and in that case the return value contains the result of
* the fn. The lang item must not return a structural type or else
* all heck breaks loose.
*
* For non-lang items, `dest` is always Some, and hence the result
* is written into memory somewhere. Nonetheless we return the
* actual return value of the function.
*/
// Introduce a temporary cleanup scope that will contain cleanups
// for the arguments while they are being evaluated. The purpose
// this cleanup is to ensure that, should a failure occur while
// evaluating argument N, the values for arguments 0...N-1 are all
// cleaned up. If no failure occurs, the values are handed off to
// the callee, and hence none of the cleanups in this temporary
// scope will ever execute.
let fcx = bcx.fcx;
let ccx = fcx.ccx;
let arg_cleanup_scope = fcx.push_custom_cleanup_scope();
let callee = get_callee(bcx, cleanup::CustomScope(arg_cleanup_scope));
let mut bcx = callee.bcx;
let (llfn, llenv, llself) = match callee.data {
Fn(llfn) => {
(llfn, None, None)
}
TraitMethod(d) => {
(d.llfn, None, Some(d.llself))
}
Closure(d) => {
// Closures are represented as (llfn, llclosure) pair:
// load the requisite values out.
let pair = d.to_llref();
let llfn = GEPi(bcx, pair, [0u, abi::fn_field_code]);
let llfn = Load(bcx, llfn);
let llenv = GEPi(bcx, pair, [0u, abi::fn_field_box]);
let llenv = Load(bcx, llenv);
(llfn, Some(llenv), None)
}
};
let (abi, ret_ty) = match ty::get(callee_ty).sty {
ty::ty_bare_fn(ref f) => (f.abi, f.sig.output),
ty::ty_closure(ref f) => (synabi::Rust, f.sig.output),
_ => fail!("expected bare rust fn or closure in trans_call_inner")
};
let is_rust_fn = abi == synabi::Rust || abi == synabi::RustIntrinsic;
// Generate a location to store the result. If the user does
// not care about the result, just make a stack slot.
let opt_llretslot = match dest {
None => {
assert!(!type_of::return_uses_outptr(ccx, ret_ty));
None
}
Some(expr::SaveIn(dst)) => Some(dst),
Some(expr::Ignore) => {
if !type_is_zero_size(ccx, ret_ty) {
Some(alloc_ty(bcx, ret_ty, "__llret"))
} else {
let llty = type_of::type_of(ccx, ret_ty);
Some(C_undef(llty.ptr_to()))
}
}
};
let mut llresult = unsafe {
llvm::LLVMGetUndef(Type::nil(ccx).ptr_to().to_ref())
};
// The code below invokes the function, using either the Rust
// conventions (if it is a rust fn) or the native conventions
// (otherwise). The important part is that, when all is sad
// and done, either the return value of the function will have been
// written in opt_llretslot (if it is Some) or `llresult` will be
// set appropriately (otherwise).
if is_rust_fn {
let mut llargs = Vec::new();
// Push the out-pointer if we use an out-pointer for this
// return type, otherwise push "undef".
if type_of::return_uses_outptr(ccx, ret_ty) {
llargs.push(opt_llretslot.unwrap());
}
// start at 1, because index 0 is the return value of the llvm func
let mut first_arg_offset = 1;
// Push the environment (or a trait object's self).
match (llenv, llself) {
(Some(llenv), None) => {
first_arg_offset += 1;
llargs.push(llenv)
},
(None, Some(llself)) => llargs.push(llself),
_ => {}
}
// Push the arguments.
bcx = trans_args(bcx, args, callee_ty, &mut llargs,
cleanup::CustomScope(arg_cleanup_scope),
llself.is_some());
fcx.pop_custom_cleanup_scope(arg_cleanup_scope);
// A function pointer is called without the declaration
// available, so we have to apply any attributes with ABI
// implications directly to the call instruction. Right now,
// the only attribute we need to worry about is `sret`.
let mut attrs = Vec::new();
if type_of::return_uses_outptr(ccx, ret_ty) {
attrs.push((1, StructRetAttribute));
// The outptr can be noalias and nocapture because it's entirely
// invisible to the program.
attrs.push((1, NoAliasAttribute));
attrs.push((1, NoCaptureAttribute));
first_arg_offset += 1;
}
// The `noalias` attribute on the return value is useful to a
// function ptr caller.
match ty::get(ret_ty).sty {
// `~` pointer return values never alias because ownership
// is transferred
ty::ty_uniq(ty) => match ty::get(ty).sty {
ty::ty_str => {}
_ => attrs.push((0, NoAliasAttribute)),
},
_ => {}
}
debug!("trans_callee_inner: first_arg_offset={}", first_arg_offset);
for (idx, &t) in ty::ty_fn_args(callee_ty).iter().enumerate()
.map(|(i, v)| (i+first_arg_offset, v)) {
use middle::ty::{BrAnon, ReLateBound};
if !type_is_immediate(ccx, t) {
// if it's not immediate, we have a program-invisible pointer,
// which it can't possibly capture
attrs.push((idx, NoCaptureAttribute));
debug!("trans_callee_inner: argument {} nocapture because it's non-immediate", idx);
continue;
}
let t_ = ty::get(t);
match t_.sty {
ty::ty_rptr(ReLateBound(_, BrAnon(_)), _) => {
debug!("trans_callee_inner: argument {} nocapture because \
of anonymous lifetime", idx);
attrs.push((idx, NoCaptureAttribute));
},
_ => { }
}
}
// Invoke the actual rust fn and update bcx/llresult.
let (llret, b) = base::invoke(bcx,
llfn,
llargs,
attrs.as_slice(),
call_info);
bcx = b;
llresult = llret;
// If the Rust convention for this type is return via
// the return value, copy it into llretslot.
match opt_llretslot {
Some(llretslot) => {
if !type_of::return_uses_outptr(bcx.ccx(), ret_ty) &&
!type_is_zero_size(bcx.ccx(), ret_ty)
{
Store(bcx, llret, llretslot);
}
}
None => {}
}
} else {
// Lang items are the only case where dest is None, and
// they are always Rust fns.
assert!(dest.is_some());
let mut llargs = Vec::new();
let arg_tys = match args {
ArgExprs(a) => a.iter().map(|x| expr_ty(bcx, *x)).collect(),
_ => fail!("expected arg exprs.")
};
bcx = trans_args(bcx, args, callee_ty, &mut llargs,
cleanup::CustomScope(arg_cleanup_scope), false);
fcx.pop_custom_cleanup_scope(arg_cleanup_scope);
bcx = foreign::trans_native_call(bcx, callee_ty,
llfn, opt_llretslot.unwrap(),
llargs.as_slice(), arg_tys);
}
// If the caller doesn't care about the result of this fn call,
// drop the temporary slot we made.
match dest {
None => {
assert!(!type_of::return_uses_outptr(bcx.ccx(), ret_ty));
}
Some(expr::Ignore) => {
// drop the value if it is not being saved.
bcx = glue::drop_ty(bcx, opt_llretslot.unwrap(), ret_ty);
}
Some(expr::SaveIn(_)) => { }
}
if ty::type_is_bot(ret_ty) {
Unreachable(bcx);
}
Result::new(bcx, llresult)
}
pub enum CallArgs<'a> {
// Supply value of arguments as a list of expressions that must be
// translated. This is used in the common case of `foo(bar, qux)`.
ArgExprs(&'a [@ast::Expr]),
// Supply value of arguments as a list of LLVM value refs; frequently
// used with lang items and so forth, when the argument is an internal
// value.
ArgVals(&'a [ValueRef]),
// For overloaded operators: `(lhs, Option(rhs, rhs_id))`. `lhs`
// is the left-hand-side and `rhs/rhs_id` is the datum/expr-id of
// the right-hand-side (if any).
ArgOverloadedOp(Datum<Expr>, Option<(Datum<Expr>, ast::NodeId)>),
}
fn trans_args<'a>(cx: &'a Block<'a>,
args: CallArgs,
fn_ty: ty::t,
llargs: &mut Vec<ValueRef> ,
arg_cleanup_scope: cleanup::ScopeId,
ignore_self: bool)
-> &'a Block<'a> {
let _icx = push_ctxt("trans_args");
let arg_tys = ty::ty_fn_args(fn_ty);
let variadic = ty::fn_is_variadic(fn_ty);
let mut bcx = cx;
// First we figure out the caller's view of the types of the arguments.
// This will be needed if this is a generic call, because the callee has
// to cast her view of the arguments to the caller's view.
match args {
ArgExprs(arg_exprs) => {
let num_formal_args = arg_tys.len();
for (i, &arg_expr) in arg_exprs.iter().enumerate() {
if i == 0 && ignore_self {
continue;
}
let arg_ty = if i >= num_formal_args {
assert!(variadic);
expr_ty_adjusted(cx, arg_expr)
} else {
*arg_tys.get(i)
};
let arg_datum = unpack_datum!(bcx, expr::trans(bcx, arg_expr));
llargs.push(unpack_result!(bcx, {
trans_arg_datum(bcx, arg_ty, arg_datum,
arg_cleanup_scope,
DontAutorefArg)
}));
}
}
ArgOverloadedOp(lhs, rhs) => {
assert!(!variadic);
llargs.push(unpack_result!(bcx, {
trans_arg_datum(bcx, *arg_tys.get(0), lhs,
arg_cleanup_scope,
DontAutorefArg)
}));
match rhs {
Some((rhs, rhs_id)) => {
assert_eq!(arg_tys.len(), 2);
llargs.push(unpack_result!(bcx, {
trans_arg_datum(bcx, *arg_tys.get(1), rhs,
arg_cleanup_scope,
DoAutorefArg(rhs_id))
}));
}
None => assert_eq!(arg_tys.len(), 1)
}
}
ArgVals(vs) => {
llargs.push_all(vs);
}
}
bcx
}
pub enum AutorefArg {
DontAutorefArg,
DoAutorefArg(ast::NodeId)
}
pub fn trans_arg_datum<'a>(
bcx: &'a Block<'a>,
formal_arg_ty: ty::t,
arg_datum: Datum<Expr>,
arg_cleanup_scope: cleanup::ScopeId,
autoref_arg: AutorefArg)
-> Result<'a> {
let _icx = push_ctxt("trans_arg_datum");
let mut bcx = bcx;
let ccx = bcx.ccx();
debug!("trans_arg_datum({})",
formal_arg_ty.repr(bcx.tcx()));
let arg_datum_ty = arg_datum.ty;
debug!(" arg datum: {}", arg_datum.to_str(bcx.ccx()));
let mut val;
if ty::type_is_bot(arg_datum_ty) {
// For values of type _|_, we generate an
// "undef" value, as such a value should never
// be inspected. It's important for the value
// to have type lldestty (the callee's expected type).
let llformal_arg_ty = type_of::type_of(ccx, formal_arg_ty);
unsafe {
val = llvm::LLVMGetUndef(llformal_arg_ty.to_ref());
}
} else {
// FIXME(#3548) use the adjustments table
match autoref_arg {
DoAutorefArg(arg_id) => {
// We will pass argument by reference
// We want an lvalue, so that we can pass by reference and
let arg_datum = unpack_datum!(
bcx, arg_datum.to_lvalue_datum(bcx, "arg", arg_id));
val = arg_datum.val;
}
DontAutorefArg => {
// Make this an rvalue, since we are going to be
// passing ownership.
let arg_datum = unpack_datum!(
bcx, arg_datum.to_rvalue_datum(bcx, "arg"));
// Now that arg_datum is owned, get it into the appropriate
// mode (ref vs value).
let arg_datum = unpack_datum!(
bcx, arg_datum.to_appropriate_datum(bcx));
// Technically, ownership of val passes to the callee.
// However, we must cleanup should we fail before the
// callee is actually invoked.
val = arg_datum.add_clean(bcx.fcx, arg_cleanup_scope);
}
}
if formal_arg_ty != arg_datum_ty {
// this could happen due to e.g. subtyping
let llformal_arg_ty = type_of::type_of_explicit_arg(ccx, formal_arg_ty);
debug!("casting actual type ({}) to match formal ({})",
bcx.val_to_str(val), bcx.llty_str(llformal_arg_ty));
val = PointerCast(bcx, val, llformal_arg_ty);
}
}
debug!("--- trans_arg_datum passing {}", bcx.val_to_str(val));
Result::new(bcx, val)
}