BodyFarm.cpp
30.3 KB
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
//== BodyFarm.cpp - Factory for conjuring up fake bodies ----------*- C++ -*-//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// BodyFarm is a factory for creating faux implementations for functions/methods
// for analysis purposes.
//
//===----------------------------------------------------------------------===//
#include "clang/Analysis/BodyFarm.h"
#include "clang/AST/ASTContext.h"
#include "clang/AST/CXXInheritance.h"
#include "clang/AST/Decl.h"
#include "clang/AST/Expr.h"
#include "clang/AST/ExprCXX.h"
#include "clang/AST/ExprObjC.h"
#include "clang/AST/NestedNameSpecifier.h"
#include "clang/Analysis/CodeInjector.h"
#include "clang/Basic/OperatorKinds.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/Debug.h"
#define DEBUG_TYPE "body-farm"
using namespace clang;
//===----------------------------------------------------------------------===//
// Helper creation functions for constructing faux ASTs.
//===----------------------------------------------------------------------===//
static bool isDispatchBlock(QualType Ty) {
// Is it a block pointer?
const BlockPointerType *BPT = Ty->getAs<BlockPointerType>();
if (!BPT)
return false;
// Check if the block pointer type takes no arguments and
// returns void.
const FunctionProtoType *FT =
BPT->getPointeeType()->getAs<FunctionProtoType>();
return FT && FT->getReturnType()->isVoidType() && FT->getNumParams() == 0;
}
namespace {
class ASTMaker {
public:
ASTMaker(ASTContext &C) : C(C) {}
/// Create a new BinaryOperator representing a simple assignment.
BinaryOperator *makeAssignment(const Expr *LHS, const Expr *RHS, QualType Ty);
/// Create a new BinaryOperator representing a comparison.
BinaryOperator *makeComparison(const Expr *LHS, const Expr *RHS,
BinaryOperator::Opcode Op);
/// Create a new compound stmt using the provided statements.
CompoundStmt *makeCompound(ArrayRef<Stmt*>);
/// Create a new DeclRefExpr for the referenced variable.
DeclRefExpr *makeDeclRefExpr(const VarDecl *D,
bool RefersToEnclosingVariableOrCapture = false);
/// Create a new UnaryOperator representing a dereference.
UnaryOperator *makeDereference(const Expr *Arg, QualType Ty);
/// Create an implicit cast for an integer conversion.
Expr *makeIntegralCast(const Expr *Arg, QualType Ty);
/// Create an implicit cast to a builtin boolean type.
ImplicitCastExpr *makeIntegralCastToBoolean(const Expr *Arg);
/// Create an implicit cast for lvalue-to-rvaluate conversions.
ImplicitCastExpr *makeLvalueToRvalue(const Expr *Arg, QualType Ty);
/// Make RValue out of variable declaration, creating a temporary
/// DeclRefExpr in the process.
ImplicitCastExpr *
makeLvalueToRvalue(const VarDecl *Decl,
bool RefersToEnclosingVariableOrCapture = false);
/// Create an implicit cast of the given type.
ImplicitCastExpr *makeImplicitCast(const Expr *Arg, QualType Ty,
CastKind CK = CK_LValueToRValue);
/// Create an Objective-C bool literal.
ObjCBoolLiteralExpr *makeObjCBool(bool Val);
/// Create an Objective-C ivar reference.
ObjCIvarRefExpr *makeObjCIvarRef(const Expr *Base, const ObjCIvarDecl *IVar);
/// Create a Return statement.
ReturnStmt *makeReturn(const Expr *RetVal);
/// Create an integer literal expression of the given type.
IntegerLiteral *makeIntegerLiteral(uint64_t Value, QualType Ty);
/// Create a member expression.
MemberExpr *makeMemberExpression(Expr *base, ValueDecl *MemberDecl,
bool IsArrow = false,
ExprValueKind ValueKind = VK_LValue);
/// Returns a *first* member field of a record declaration with a given name.
/// \return an nullptr if no member with such a name exists.
ValueDecl *findMemberField(const RecordDecl *RD, StringRef Name);
private:
ASTContext &C;
};
}
BinaryOperator *ASTMaker::makeAssignment(const Expr *LHS, const Expr *RHS,
QualType Ty) {
return BinaryOperator::Create(
C, const_cast<Expr *>(LHS), const_cast<Expr *>(RHS), BO_Assign, Ty,
VK_RValue, OK_Ordinary, SourceLocation(), FPOptionsOverride());
}
BinaryOperator *ASTMaker::makeComparison(const Expr *LHS, const Expr *RHS,
BinaryOperator::Opcode Op) {
assert(BinaryOperator::isLogicalOp(Op) ||
BinaryOperator::isComparisonOp(Op));
return BinaryOperator::Create(
C, const_cast<Expr *>(LHS), const_cast<Expr *>(RHS), Op,
C.getLogicalOperationType(), VK_RValue, OK_Ordinary, SourceLocation(),
FPOptionsOverride());
}
CompoundStmt *ASTMaker::makeCompound(ArrayRef<Stmt *> Stmts) {
return CompoundStmt::Create(C, Stmts, SourceLocation(), SourceLocation());
}
DeclRefExpr *ASTMaker::makeDeclRefExpr(
const VarDecl *D,
bool RefersToEnclosingVariableOrCapture) {
QualType Type = D->getType().getNonReferenceType();
DeclRefExpr *DR = DeclRefExpr::Create(
C, NestedNameSpecifierLoc(), SourceLocation(), const_cast<VarDecl *>(D),
RefersToEnclosingVariableOrCapture, SourceLocation(), Type, VK_LValue);
return DR;
}
UnaryOperator *ASTMaker::makeDereference(const Expr *Arg, QualType Ty) {
return UnaryOperator::Create(C, const_cast<Expr *>(Arg), UO_Deref, Ty,
VK_LValue, OK_Ordinary, SourceLocation(),
/*CanOverflow*/ false, FPOptionsOverride());
}
ImplicitCastExpr *ASTMaker::makeLvalueToRvalue(const Expr *Arg, QualType Ty) {
return makeImplicitCast(Arg, Ty, CK_LValueToRValue);
}
ImplicitCastExpr *
ASTMaker::makeLvalueToRvalue(const VarDecl *Arg,
bool RefersToEnclosingVariableOrCapture) {
QualType Type = Arg->getType().getNonReferenceType();
return makeLvalueToRvalue(makeDeclRefExpr(Arg,
RefersToEnclosingVariableOrCapture),
Type);
}
ImplicitCastExpr *ASTMaker::makeImplicitCast(const Expr *Arg, QualType Ty,
CastKind CK) {
return ImplicitCastExpr::Create(C, Ty,
/* CastKind=*/CK,
/* Expr=*/const_cast<Expr *>(Arg),
/* CXXCastPath=*/nullptr,
/* ExprValueKind=*/VK_RValue,
/* FPFeatures */ FPOptionsOverride());
}
Expr *ASTMaker::makeIntegralCast(const Expr *Arg, QualType Ty) {
if (Arg->getType() == Ty)
return const_cast<Expr*>(Arg);
return makeImplicitCast(Arg, Ty, CK_IntegralCast);
}
ImplicitCastExpr *ASTMaker::makeIntegralCastToBoolean(const Expr *Arg) {
return makeImplicitCast(Arg, C.BoolTy, CK_IntegralToBoolean);
}
ObjCBoolLiteralExpr *ASTMaker::makeObjCBool(bool Val) {
QualType Ty = C.getBOOLDecl() ? C.getBOOLType() : C.ObjCBuiltinBoolTy;
return new (C) ObjCBoolLiteralExpr(Val, Ty, SourceLocation());
}
ObjCIvarRefExpr *ASTMaker::makeObjCIvarRef(const Expr *Base,
const ObjCIvarDecl *IVar) {
return new (C) ObjCIvarRefExpr(const_cast<ObjCIvarDecl*>(IVar),
IVar->getType(), SourceLocation(),
SourceLocation(), const_cast<Expr*>(Base),
/*arrow=*/true, /*free=*/false);
}
ReturnStmt *ASTMaker::makeReturn(const Expr *RetVal) {
return ReturnStmt::Create(C, SourceLocation(), const_cast<Expr *>(RetVal),
/* NRVOCandidate=*/nullptr);
}
IntegerLiteral *ASTMaker::makeIntegerLiteral(uint64_t Value, QualType Ty) {
llvm::APInt APValue = llvm::APInt(C.getTypeSize(Ty), Value);
return IntegerLiteral::Create(C, APValue, Ty, SourceLocation());
}
MemberExpr *ASTMaker::makeMemberExpression(Expr *base, ValueDecl *MemberDecl,
bool IsArrow,
ExprValueKind ValueKind) {
DeclAccessPair FoundDecl = DeclAccessPair::make(MemberDecl, AS_public);
return MemberExpr::Create(
C, base, IsArrow, SourceLocation(), NestedNameSpecifierLoc(),
SourceLocation(), MemberDecl, FoundDecl,
DeclarationNameInfo(MemberDecl->getDeclName(), SourceLocation()),
/* TemplateArgumentListInfo=*/ nullptr, MemberDecl->getType(), ValueKind,
OK_Ordinary, NOUR_None);
}
ValueDecl *ASTMaker::findMemberField(const RecordDecl *RD, StringRef Name) {
CXXBasePaths Paths(
/* FindAmbiguities=*/false,
/* RecordPaths=*/false,
/* DetectVirtual=*/ false);
const IdentifierInfo &II = C.Idents.get(Name);
DeclarationName DeclName = C.DeclarationNames.getIdentifier(&II);
DeclContextLookupResult Decls = RD->lookup(DeclName);
for (NamedDecl *FoundDecl : Decls)
if (!FoundDecl->getDeclContext()->isFunctionOrMethod())
return cast<ValueDecl>(FoundDecl);
return nullptr;
}
//===----------------------------------------------------------------------===//
// Creation functions for faux ASTs.
//===----------------------------------------------------------------------===//
typedef Stmt *(*FunctionFarmer)(ASTContext &C, const FunctionDecl *D);
static CallExpr *create_call_once_funcptr_call(ASTContext &C, ASTMaker M,
const ParmVarDecl *Callback,
ArrayRef<Expr *> CallArgs) {
QualType Ty = Callback->getType();
DeclRefExpr *Call = M.makeDeclRefExpr(Callback);
Expr *SubExpr;
if (Ty->isRValueReferenceType()) {
SubExpr = M.makeImplicitCast(
Call, Ty.getNonReferenceType(), CK_LValueToRValue);
} else if (Ty->isLValueReferenceType() &&
Call->getType()->isFunctionType()) {
Ty = C.getPointerType(Ty.getNonReferenceType());
SubExpr = M.makeImplicitCast(Call, Ty, CK_FunctionToPointerDecay);
} else if (Ty->isLValueReferenceType()
&& Call->getType()->isPointerType()
&& Call->getType()->getPointeeType()->isFunctionType()){
SubExpr = Call;
} else {
llvm_unreachable("Unexpected state");
}
return CallExpr::Create(C, SubExpr, CallArgs, C.VoidTy, VK_RValue,
SourceLocation(), FPOptionsOverride());
}
static CallExpr *create_call_once_lambda_call(ASTContext &C, ASTMaker M,
const ParmVarDecl *Callback,
CXXRecordDecl *CallbackDecl,
ArrayRef<Expr *> CallArgs) {
assert(CallbackDecl != nullptr);
assert(CallbackDecl->isLambda());
FunctionDecl *callOperatorDecl = CallbackDecl->getLambdaCallOperator();
assert(callOperatorDecl != nullptr);
DeclRefExpr *callOperatorDeclRef =
DeclRefExpr::Create(/* Ctx =*/ C,
/* QualifierLoc =*/ NestedNameSpecifierLoc(),
/* TemplateKWLoc =*/ SourceLocation(),
const_cast<FunctionDecl *>(callOperatorDecl),
/* RefersToEnclosingVariableOrCapture=*/ false,
/* NameLoc =*/ SourceLocation(),
/* T =*/ callOperatorDecl->getType(),
/* VK =*/ VK_LValue);
return CXXOperatorCallExpr::Create(
/*AstContext=*/C, OO_Call, callOperatorDeclRef,
/*Args=*/CallArgs,
/*QualType=*/C.VoidTy,
/*ExprValueType=*/VK_RValue,
/*SourceLocation=*/SourceLocation(),
/*FPFeatures=*/FPOptionsOverride());
}
/// Create a fake body for std::call_once.
/// Emulates the following function body:
///
/// \code
/// typedef struct once_flag_s {
/// unsigned long __state = 0;
/// } once_flag;
/// template<class Callable>
/// void call_once(once_flag& o, Callable func) {
/// if (!o.__state) {
/// func();
/// }
/// o.__state = 1;
/// }
/// \endcode
static Stmt *create_call_once(ASTContext &C, const FunctionDecl *D) {
LLVM_DEBUG(llvm::dbgs() << "Generating body for call_once\n");
// We need at least two parameters.
if (D->param_size() < 2)
return nullptr;
ASTMaker M(C);
const ParmVarDecl *Flag = D->getParamDecl(0);
const ParmVarDecl *Callback = D->getParamDecl(1);
if (!Callback->getType()->isReferenceType()) {
llvm::dbgs() << "libcxx03 std::call_once implementation, skipping.\n";
return nullptr;
}
if (!Flag->getType()->isReferenceType()) {
llvm::dbgs() << "unknown std::call_once implementation, skipping.\n";
return nullptr;
}
QualType CallbackType = Callback->getType().getNonReferenceType();
// Nullable pointer, non-null iff function is a CXXRecordDecl.
CXXRecordDecl *CallbackRecordDecl = CallbackType->getAsCXXRecordDecl();
QualType FlagType = Flag->getType().getNonReferenceType();
auto *FlagRecordDecl = FlagType->getAsRecordDecl();
if (!FlagRecordDecl) {
LLVM_DEBUG(llvm::dbgs() << "Flag field is not a record: "
<< "unknown std::call_once implementation, "
<< "ignoring the call.\n");
return nullptr;
}
// We initially assume libc++ implementation of call_once,
// where the once_flag struct has a field `__state_`.
ValueDecl *FlagFieldDecl = M.findMemberField(FlagRecordDecl, "__state_");
// Otherwise, try libstdc++ implementation, with a field
// `_M_once`
if (!FlagFieldDecl) {
FlagFieldDecl = M.findMemberField(FlagRecordDecl, "_M_once");
}
if (!FlagFieldDecl) {
LLVM_DEBUG(llvm::dbgs() << "No field _M_once or __state_ found on "
<< "std::once_flag struct: unknown std::call_once "
<< "implementation, ignoring the call.");
return nullptr;
}
bool isLambdaCall = CallbackRecordDecl && CallbackRecordDecl->isLambda();
if (CallbackRecordDecl && !isLambdaCall) {
LLVM_DEBUG(llvm::dbgs()
<< "Not supported: synthesizing body for functors when "
<< "body farming std::call_once, ignoring the call.");
return nullptr;
}
SmallVector<Expr *, 5> CallArgs;
const FunctionProtoType *CallbackFunctionType;
if (isLambdaCall) {
// Lambda requires callback itself inserted as a first parameter.
CallArgs.push_back(
M.makeDeclRefExpr(Callback,
/* RefersToEnclosingVariableOrCapture=*/ true));
CallbackFunctionType = CallbackRecordDecl->getLambdaCallOperator()
->getType()
->getAs<FunctionProtoType>();
} else if (!CallbackType->getPointeeType().isNull()) {
CallbackFunctionType =
CallbackType->getPointeeType()->getAs<FunctionProtoType>();
} else {
CallbackFunctionType = CallbackType->getAs<FunctionProtoType>();
}
if (!CallbackFunctionType)
return nullptr;
// First two arguments are used for the flag and for the callback.
if (D->getNumParams() != CallbackFunctionType->getNumParams() + 2) {
LLVM_DEBUG(llvm::dbgs() << "Types of params of the callback do not match "
<< "params passed to std::call_once, "
<< "ignoring the call\n");
return nullptr;
}
// All arguments past first two ones are passed to the callback,
// and we turn lvalues into rvalues if the argument is not passed by
// reference.
for (unsigned int ParamIdx = 2; ParamIdx < D->getNumParams(); ParamIdx++) {
const ParmVarDecl *PDecl = D->getParamDecl(ParamIdx);
assert(PDecl);
if (CallbackFunctionType->getParamType(ParamIdx - 2)
.getNonReferenceType()
.getCanonicalType() !=
PDecl->getType().getNonReferenceType().getCanonicalType()) {
LLVM_DEBUG(llvm::dbgs() << "Types of params of the callback do not match "
<< "params passed to std::call_once, "
<< "ignoring the call\n");
return nullptr;
}
Expr *ParamExpr = M.makeDeclRefExpr(PDecl);
if (!CallbackFunctionType->getParamType(ParamIdx - 2)->isReferenceType()) {
QualType PTy = PDecl->getType().getNonReferenceType();
ParamExpr = M.makeLvalueToRvalue(ParamExpr, PTy);
}
CallArgs.push_back(ParamExpr);
}
CallExpr *CallbackCall;
if (isLambdaCall) {
CallbackCall = create_call_once_lambda_call(C, M, Callback,
CallbackRecordDecl, CallArgs);
} else {
// Function pointer case.
CallbackCall = create_call_once_funcptr_call(C, M, Callback, CallArgs);
}
DeclRefExpr *FlagDecl =
M.makeDeclRefExpr(Flag,
/* RefersToEnclosingVariableOrCapture=*/true);
MemberExpr *Deref = M.makeMemberExpression(FlagDecl, FlagFieldDecl);
assert(Deref->isLValue());
QualType DerefType = Deref->getType();
// Negation predicate.
UnaryOperator *FlagCheck = UnaryOperator::Create(
C,
/* input=*/
M.makeImplicitCast(M.makeLvalueToRvalue(Deref, DerefType), DerefType,
CK_IntegralToBoolean),
/* opc=*/UO_LNot,
/* QualType=*/C.IntTy,
/* ExprValueKind=*/VK_RValue,
/* ExprObjectKind=*/OK_Ordinary, SourceLocation(),
/* CanOverflow*/ false, FPOptionsOverride());
// Create assignment.
BinaryOperator *FlagAssignment = M.makeAssignment(
Deref, M.makeIntegralCast(M.makeIntegerLiteral(1, C.IntTy), DerefType),
DerefType);
auto *Out =
IfStmt::Create(C, SourceLocation(),
/* IsConstexpr=*/false,
/* Init=*/nullptr,
/* Var=*/nullptr,
/* Cond=*/FlagCheck,
/* LPL=*/SourceLocation(),
/* RPL=*/SourceLocation(),
/* Then=*/M.makeCompound({CallbackCall, FlagAssignment}));
return Out;
}
/// Create a fake body for dispatch_once.
static Stmt *create_dispatch_once(ASTContext &C, const FunctionDecl *D) {
// Check if we have at least two parameters.
if (D->param_size() != 2)
return nullptr;
// Check if the first parameter is a pointer to integer type.
const ParmVarDecl *Predicate = D->getParamDecl(0);
QualType PredicateQPtrTy = Predicate->getType();
const PointerType *PredicatePtrTy = PredicateQPtrTy->getAs<PointerType>();
if (!PredicatePtrTy)
return nullptr;
QualType PredicateTy = PredicatePtrTy->getPointeeType();
if (!PredicateTy->isIntegerType())
return nullptr;
// Check if the second parameter is the proper block type.
const ParmVarDecl *Block = D->getParamDecl(1);
QualType Ty = Block->getType();
if (!isDispatchBlock(Ty))
return nullptr;
// Everything checks out. Create a fakse body that checks the predicate,
// sets it, and calls the block. Basically, an AST dump of:
//
// void dispatch_once(dispatch_once_t *predicate, dispatch_block_t block) {
// if (*predicate != ~0l) {
// *predicate = ~0l;
// block();
// }
// }
ASTMaker M(C);
// (1) Create the call.
CallExpr *CE = CallExpr::Create(
/*ASTContext=*/C,
/*StmtClass=*/M.makeLvalueToRvalue(/*Expr=*/Block),
/*Args=*/None,
/*QualType=*/C.VoidTy,
/*ExprValueType=*/VK_RValue,
/*SourceLocation=*/SourceLocation(), FPOptionsOverride());
// (2) Create the assignment to the predicate.
Expr *DoneValue =
UnaryOperator::Create(C, M.makeIntegerLiteral(0, C.LongTy), UO_Not,
C.LongTy, VK_RValue, OK_Ordinary, SourceLocation(),
/*CanOverflow*/ false, FPOptionsOverride());
BinaryOperator *B =
M.makeAssignment(
M.makeDereference(
M.makeLvalueToRvalue(
M.makeDeclRefExpr(Predicate), PredicateQPtrTy),
PredicateTy),
M.makeIntegralCast(DoneValue, PredicateTy),
PredicateTy);
// (3) Create the compound statement.
Stmt *Stmts[] = { B, CE };
CompoundStmt *CS = M.makeCompound(Stmts);
// (4) Create the 'if' condition.
ImplicitCastExpr *LValToRval =
M.makeLvalueToRvalue(
M.makeDereference(
M.makeLvalueToRvalue(
M.makeDeclRefExpr(Predicate),
PredicateQPtrTy),
PredicateTy),
PredicateTy);
Expr *GuardCondition = M.makeComparison(LValToRval, DoneValue, BO_NE);
// (5) Create the 'if' statement.
auto *If = IfStmt::Create(C, SourceLocation(),
/* IsConstexpr=*/false,
/* Init=*/nullptr,
/* Var=*/nullptr,
/* Cond=*/GuardCondition,
/* LPL=*/SourceLocation(),
/* RPL=*/SourceLocation(),
/* Then=*/CS);
return If;
}
/// Create a fake body for dispatch_sync.
static Stmt *create_dispatch_sync(ASTContext &C, const FunctionDecl *D) {
// Check if we have at least two parameters.
if (D->param_size() != 2)
return nullptr;
// Check if the second parameter is a block.
const ParmVarDecl *PV = D->getParamDecl(1);
QualType Ty = PV->getType();
if (!isDispatchBlock(Ty))
return nullptr;
// Everything checks out. Create a fake body that just calls the block.
// This is basically just an AST dump of:
//
// void dispatch_sync(dispatch_queue_t queue, void (^block)(void)) {
// block();
// }
//
ASTMaker M(C);
DeclRefExpr *DR = M.makeDeclRefExpr(PV);
ImplicitCastExpr *ICE = M.makeLvalueToRvalue(DR, Ty);
CallExpr *CE = CallExpr::Create(C, ICE, None, C.VoidTy, VK_RValue,
SourceLocation(), FPOptionsOverride());
return CE;
}
static Stmt *create_OSAtomicCompareAndSwap(ASTContext &C, const FunctionDecl *D)
{
// There are exactly 3 arguments.
if (D->param_size() != 3)
return nullptr;
// Signature:
// _Bool OSAtomicCompareAndSwapPtr(void *__oldValue,
// void *__newValue,
// void * volatile *__theValue)
// Generate body:
// if (oldValue == *theValue) {
// *theValue = newValue;
// return YES;
// }
// else return NO;
QualType ResultTy = D->getReturnType();
bool isBoolean = ResultTy->isBooleanType();
if (!isBoolean && !ResultTy->isIntegralType(C))
return nullptr;
const ParmVarDecl *OldValue = D->getParamDecl(0);
QualType OldValueTy = OldValue->getType();
const ParmVarDecl *NewValue = D->getParamDecl(1);
QualType NewValueTy = NewValue->getType();
assert(OldValueTy == NewValueTy);
const ParmVarDecl *TheValue = D->getParamDecl(2);
QualType TheValueTy = TheValue->getType();
const PointerType *PT = TheValueTy->getAs<PointerType>();
if (!PT)
return nullptr;
QualType PointeeTy = PT->getPointeeType();
ASTMaker M(C);
// Construct the comparison.
Expr *Comparison =
M.makeComparison(
M.makeLvalueToRvalue(M.makeDeclRefExpr(OldValue), OldValueTy),
M.makeLvalueToRvalue(
M.makeDereference(
M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy),
PointeeTy),
PointeeTy),
BO_EQ);
// Construct the body of the IfStmt.
Stmt *Stmts[2];
Stmts[0] =
M.makeAssignment(
M.makeDereference(
M.makeLvalueToRvalue(M.makeDeclRefExpr(TheValue), TheValueTy),
PointeeTy),
M.makeLvalueToRvalue(M.makeDeclRefExpr(NewValue), NewValueTy),
NewValueTy);
Expr *BoolVal = M.makeObjCBool(true);
Expr *RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal)
: M.makeIntegralCast(BoolVal, ResultTy);
Stmts[1] = M.makeReturn(RetVal);
CompoundStmt *Body = M.makeCompound(Stmts);
// Construct the else clause.
BoolVal = M.makeObjCBool(false);
RetVal = isBoolean ? M.makeIntegralCastToBoolean(BoolVal)
: M.makeIntegralCast(BoolVal, ResultTy);
Stmt *Else = M.makeReturn(RetVal);
/// Construct the If.
auto *If =
IfStmt::Create(C, SourceLocation(),
/* IsConstexpr=*/false,
/* Init=*/nullptr,
/* Var=*/nullptr, Comparison,
/* LPL=*/SourceLocation(),
/* RPL=*/SourceLocation(), Body, SourceLocation(), Else);
return If;
}
Stmt *BodyFarm::getBody(const FunctionDecl *D) {
Optional<Stmt *> &Val = Bodies[D];
if (Val.hasValue())
return Val.getValue();
Val = nullptr;
if (D->getIdentifier() == nullptr)
return nullptr;
StringRef Name = D->getName();
if (Name.empty())
return nullptr;
FunctionFarmer FF;
if (Name.startswith("OSAtomicCompareAndSwap") ||
Name.startswith("objc_atomicCompareAndSwap")) {
FF = create_OSAtomicCompareAndSwap;
} else if (Name == "call_once" && D->getDeclContext()->isStdNamespace()) {
FF = create_call_once;
} else {
FF = llvm::StringSwitch<FunctionFarmer>(Name)
.Case("dispatch_sync", create_dispatch_sync)
.Case("dispatch_once", create_dispatch_once)
.Default(nullptr);
}
if (FF) { Val = FF(C, D); }
else if (Injector) { Val = Injector->getBody(D); }
return Val.getValue();
}
static const ObjCIvarDecl *findBackingIvar(const ObjCPropertyDecl *Prop) {
const ObjCIvarDecl *IVar = Prop->getPropertyIvarDecl();
if (IVar)
return IVar;
// When a readonly property is shadowed in a class extensions with a
// a readwrite property, the instance variable belongs to the shadowing
// property rather than the shadowed property. If there is no instance
// variable on a readonly property, check to see whether the property is
// shadowed and if so try to get the instance variable from shadowing
// property.
if (!Prop->isReadOnly())
return nullptr;
auto *Container = cast<ObjCContainerDecl>(Prop->getDeclContext());
const ObjCInterfaceDecl *PrimaryInterface = nullptr;
if (auto *InterfaceDecl = dyn_cast<ObjCInterfaceDecl>(Container)) {
PrimaryInterface = InterfaceDecl;
} else if (auto *CategoryDecl = dyn_cast<ObjCCategoryDecl>(Container)) {
PrimaryInterface = CategoryDecl->getClassInterface();
} else if (auto *ImplDecl = dyn_cast<ObjCImplDecl>(Container)) {
PrimaryInterface = ImplDecl->getClassInterface();
} else {
return nullptr;
}
// FindPropertyVisibleInPrimaryClass() looks first in class extensions, so it
// is guaranteed to find the shadowing property, if it exists, rather than
// the shadowed property.
auto *ShadowingProp = PrimaryInterface->FindPropertyVisibleInPrimaryClass(
Prop->getIdentifier(), Prop->getQueryKind());
if (ShadowingProp && ShadowingProp != Prop) {
IVar = ShadowingProp->getPropertyIvarDecl();
}
return IVar;
}
static Stmt *createObjCPropertyGetter(ASTContext &Ctx,
const ObjCMethodDecl *MD) {
// First, find the backing ivar.
const ObjCIvarDecl *IVar = nullptr;
// Property accessor stubs sometimes do not correspond to any property decl
// in the current interface (but in a superclass). They still have a
// corresponding property impl decl in this case.
if (MD->isSynthesizedAccessorStub()) {
const ObjCInterfaceDecl *IntD = MD->getClassInterface();
const ObjCImplementationDecl *ImpD = IntD->getImplementation();
for (const auto *PI: ImpD->property_impls()) {
if (const ObjCPropertyDecl *P = PI->getPropertyDecl()) {
if (P->getGetterName() == MD->getSelector())
IVar = P->getPropertyIvarDecl();
}
}
}
if (!IVar) {
const ObjCPropertyDecl *Prop = MD->findPropertyDecl();
IVar = findBackingIvar(Prop);
if (!IVar)
return nullptr;
// Ignore weak variables, which have special behavior.
if (Prop->getPropertyAttributes() & ObjCPropertyAttribute::kind_weak)
return nullptr;
// Look to see if Sema has synthesized a body for us. This happens in
// Objective-C++ because the return value may be a C++ class type with a
// non-trivial copy constructor. We can only do this if we can find the
// @synthesize for this property, though (or if we know it's been auto-
// synthesized).
const ObjCImplementationDecl *ImplDecl =
IVar->getContainingInterface()->getImplementation();
if (ImplDecl) {
for (const auto *I : ImplDecl->property_impls()) {
if (I->getPropertyDecl() != Prop)
continue;
if (I->getGetterCXXConstructor()) {
ASTMaker M(Ctx);
return M.makeReturn(I->getGetterCXXConstructor());
}
}
}
// Sanity check that the property is the same type as the ivar, or a
// reference to it, and that it is either an object pointer or trivially
// copyable.
if (!Ctx.hasSameUnqualifiedType(IVar->getType(),
Prop->getType().getNonReferenceType()))
return nullptr;
if (!IVar->getType()->isObjCLifetimeType() &&
!IVar->getType().isTriviallyCopyableType(Ctx))
return nullptr;
}
// Generate our body:
// return self->_ivar;
ASTMaker M(Ctx);
const VarDecl *selfVar = MD->getSelfDecl();
if (!selfVar)
return nullptr;
Expr *loadedIVar =
M.makeObjCIvarRef(
M.makeLvalueToRvalue(
M.makeDeclRefExpr(selfVar),
selfVar->getType()),
IVar);
if (!MD->getReturnType()->isReferenceType())
loadedIVar = M.makeLvalueToRvalue(loadedIVar, IVar->getType());
return M.makeReturn(loadedIVar);
}
Stmt *BodyFarm::getBody(const ObjCMethodDecl *D) {
// We currently only know how to synthesize property accessors.
if (!D->isPropertyAccessor())
return nullptr;
D = D->getCanonicalDecl();
// We should not try to synthesize explicitly redefined accessors.
// We do not know for sure how they behave.
if (!D->isImplicit())
return nullptr;
Optional<Stmt *> &Val = Bodies[D];
if (Val.hasValue())
return Val.getValue();
Val = nullptr;
// For now, we only synthesize getters.
// Synthesizing setters would cause false negatives in the
// RetainCountChecker because the method body would bind the parameter
// to an instance variable, causing it to escape. This would prevent
// warning in the following common scenario:
//
// id foo = [[NSObject alloc] init];
// self.foo = foo; // We should warn that foo leaks here.
//
if (D->param_size() != 0)
return nullptr;
// If the property was defined in an extension, search the extensions for
// overrides.
const ObjCInterfaceDecl *OID = D->getClassInterface();
if (dyn_cast<ObjCInterfaceDecl>(D->getParent()) != OID)
for (auto *Ext : OID->known_extensions()) {
auto *OMD = Ext->getInstanceMethod(D->getSelector());
if (OMD && !OMD->isImplicit())
return nullptr;
}
Val = createObjCPropertyGetter(C, D);
return Val.getValue();
}