aboutsummaryrefslogtreecommitdiffstats
path: root/contrib/libs/llvm14/lib/Transforms/Instrumentation/ThreadSanitizer.cpp
blob: 180012198c42cf06ddcdb33b2ad8e1c441018581 (plain) (blame)
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
//===-- ThreadSanitizer.cpp - race detector -------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file is a part of ThreadSanitizer, a race detector.
//
// The tool is under development, for the details about previous versions see
// http://code.google.com/p/data-race-test
//
// The instrumentation phase is quite simple:
//   - Insert calls to run-time library before every memory access.
//      - Optimizations may apply to avoid instrumenting some of the accesses.
//   - Insert calls at function entry/exit.
// The rest is handled by the run-time library.
//===----------------------------------------------------------------------===//

#include "llvm/Transforms/Instrumentation/ThreadSanitizer.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/Optional.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/CaptureTracking.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/InitializePasses.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/EscapeEnumerator.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"

using namespace llvm;

#define DEBUG_TYPE "tsan"

static cl::opt<bool> ClInstrumentMemoryAccesses(
    "tsan-instrument-memory-accesses", cl::init(true),
    cl::desc("Instrument memory accesses"), cl::Hidden);
static cl::opt<bool>
    ClInstrumentFuncEntryExit("tsan-instrument-func-entry-exit", cl::init(true),
                              cl::desc("Instrument function entry and exit"),
                              cl::Hidden);
static cl::opt<bool> ClHandleCxxExceptions(
    "tsan-handle-cxx-exceptions", cl::init(true),
    cl::desc("Handle C++ exceptions (insert cleanup blocks for unwinding)"),
    cl::Hidden);
static cl::opt<bool> ClInstrumentAtomics("tsan-instrument-atomics",
                                         cl::init(true),
                                         cl::desc("Instrument atomics"),
                                         cl::Hidden);
static cl::opt<bool> ClInstrumentMemIntrinsics(
    "tsan-instrument-memintrinsics", cl::init(true),
    cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden);
static cl::opt<bool> ClDistinguishVolatile(
    "tsan-distinguish-volatile", cl::init(false),
    cl::desc("Emit special instrumentation for accesses to volatiles"),
    cl::Hidden);
static cl::opt<bool> ClInstrumentReadBeforeWrite(
    "tsan-instrument-read-before-write", cl::init(false),
    cl::desc("Do not eliminate read instrumentation for read-before-writes"),
    cl::Hidden);
static cl::opt<bool> ClCompoundReadBeforeWrite(
    "tsan-compound-read-before-write", cl::init(false),
    cl::desc("Emit special compound instrumentation for reads-before-writes"),
    cl::Hidden);

STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
STATISTIC(NumOmittedReadsBeforeWrite,
          "Number of reads ignored due to following writes");
STATISTIC(NumAccessesWithBadSize, "Number of accesses with bad size");
STATISTIC(NumInstrumentedVtableWrites, "Number of vtable ptr writes");
STATISTIC(NumInstrumentedVtableReads, "Number of vtable ptr reads");
STATISTIC(NumOmittedReadsFromConstantGlobals,
          "Number of reads from constant globals");
STATISTIC(NumOmittedReadsFromVtable, "Number of vtable reads");
STATISTIC(NumOmittedNonCaptured, "Number of accesses ignored due to capturing");

const char kTsanModuleCtorName[] = "tsan.module_ctor";
const char kTsanInitName[] = "__tsan_init";

namespace {

/// ThreadSanitizer: instrument the code in module to find races.
///
/// Instantiating ThreadSanitizer inserts the tsan runtime library API function
/// declarations into the module if they don't exist already. Instantiating
/// ensures the __tsan_init function is in the list of global constructors for
/// the module.
struct ThreadSanitizer {
  ThreadSanitizer() {
    // Check options and warn user.
    if (ClInstrumentReadBeforeWrite && ClCompoundReadBeforeWrite) {
      errs()
          << "warning: Option -tsan-compound-read-before-write has no effect "
             "when -tsan-instrument-read-before-write is set.\n";
    }
  }

  bool sanitizeFunction(Function &F, const TargetLibraryInfo &TLI);

private:
  // Internal Instruction wrapper that contains more information about the
  // Instruction from prior analysis.
  struct InstructionInfo {
    // Instrumentation emitted for this instruction is for a compounded set of
    // read and write operations in the same basic block.
    static constexpr unsigned kCompoundRW = (1U << 0);

    explicit InstructionInfo(Instruction *Inst) : Inst(Inst) {}

    Instruction *Inst;
    unsigned Flags = 0;
  };

  void initialize(Module &M);
  bool instrumentLoadOrStore(const InstructionInfo &II, const DataLayout &DL);
  bool instrumentAtomic(Instruction *I, const DataLayout &DL);
  bool instrumentMemIntrinsic(Instruction *I);
  void chooseInstructionsToInstrument(SmallVectorImpl<Instruction *> &Local,
                                      SmallVectorImpl<InstructionInfo> &All,
                                      const DataLayout &DL);
  bool addrPointsToConstantData(Value *Addr);
  int getMemoryAccessFuncIndex(Type *OrigTy, Value *Addr, const DataLayout &DL);
  void InsertRuntimeIgnores(Function &F);

  Type *IntptrTy;
  FunctionCallee TsanFuncEntry;
  FunctionCallee TsanFuncExit;
  FunctionCallee TsanIgnoreBegin;
  FunctionCallee TsanIgnoreEnd;
  // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
  static const size_t kNumberOfAccessSizes = 5;
  FunctionCallee TsanRead[kNumberOfAccessSizes];
  FunctionCallee TsanWrite[kNumberOfAccessSizes];
  FunctionCallee TsanUnalignedRead[kNumberOfAccessSizes];
  FunctionCallee TsanUnalignedWrite[kNumberOfAccessSizes];
  FunctionCallee TsanVolatileRead[kNumberOfAccessSizes];
  FunctionCallee TsanVolatileWrite[kNumberOfAccessSizes];
  FunctionCallee TsanUnalignedVolatileRead[kNumberOfAccessSizes];
  FunctionCallee TsanUnalignedVolatileWrite[kNumberOfAccessSizes];
  FunctionCallee TsanCompoundRW[kNumberOfAccessSizes];
  FunctionCallee TsanUnalignedCompoundRW[kNumberOfAccessSizes];
  FunctionCallee TsanAtomicLoad[kNumberOfAccessSizes];
  FunctionCallee TsanAtomicStore[kNumberOfAccessSizes];
  FunctionCallee TsanAtomicRMW[AtomicRMWInst::LAST_BINOP + 1]
                              [kNumberOfAccessSizes];
  FunctionCallee TsanAtomicCAS[kNumberOfAccessSizes];
  FunctionCallee TsanAtomicThreadFence;
  FunctionCallee TsanAtomicSignalFence;
  FunctionCallee TsanVptrUpdate;
  FunctionCallee TsanVptrLoad;
  FunctionCallee MemmoveFn, MemcpyFn, MemsetFn;
};

struct ThreadSanitizerLegacyPass : FunctionPass {
  ThreadSanitizerLegacyPass() : FunctionPass(ID) {
    initializeThreadSanitizerLegacyPassPass(*PassRegistry::getPassRegistry());
  }
  StringRef getPassName() const override;
  void getAnalysisUsage(AnalysisUsage &AU) const override;
  bool runOnFunction(Function &F) override;
  bool doInitialization(Module &M) override;
  static char ID; // Pass identification, replacement for typeid.
private:
  Optional<ThreadSanitizer> TSan;
};

void insertModuleCtor(Module &M) {
  getOrCreateSanitizerCtorAndInitFunctions(
      M, kTsanModuleCtorName, kTsanInitName, /*InitArgTypes=*/{},
      /*InitArgs=*/{},
      // This callback is invoked when the functions are created the first
      // time. Hook them into the global ctors list in that case:
      [&](Function *Ctor, FunctionCallee) { appendToGlobalCtors(M, Ctor, 0); });
}

}  // namespace

PreservedAnalyses ThreadSanitizerPass::run(Function &F,
                                           FunctionAnalysisManager &FAM) {
  ThreadSanitizer TSan;
  if (TSan.sanitizeFunction(F, FAM.getResult<TargetLibraryAnalysis>(F)))
    return PreservedAnalyses::none();
  return PreservedAnalyses::all();
}

PreservedAnalyses ModuleThreadSanitizerPass::run(Module &M,
                                                 ModuleAnalysisManager &MAM) {
  insertModuleCtor(M);
  return PreservedAnalyses::none();
}

char ThreadSanitizerLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(ThreadSanitizerLegacyPass, "tsan",
                      "ThreadSanitizer: detects data races.", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(ThreadSanitizerLegacyPass, "tsan",
                    "ThreadSanitizer: detects data races.", false, false)

StringRef ThreadSanitizerLegacyPass::getPassName() const {
  return "ThreadSanitizerLegacyPass";
}

void ThreadSanitizerLegacyPass::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.addRequired<TargetLibraryInfoWrapperPass>();
}

bool ThreadSanitizerLegacyPass::doInitialization(Module &M) {
  insertModuleCtor(M);
  TSan.emplace();
  return true;
}

bool ThreadSanitizerLegacyPass::runOnFunction(Function &F) {
  auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
  TSan->sanitizeFunction(F, TLI);
  return true;
}

FunctionPass *llvm::createThreadSanitizerLegacyPassPass() {
  return new ThreadSanitizerLegacyPass();
}

void ThreadSanitizer::initialize(Module &M) {
  const DataLayout &DL = M.getDataLayout();
  IntptrTy = DL.getIntPtrType(M.getContext());

  IRBuilder<> IRB(M.getContext());
  AttributeList Attr;
  Attr = Attr.addFnAttribute(M.getContext(), Attribute::NoUnwind);
  // Initialize the callbacks.
  TsanFuncEntry = M.getOrInsertFunction("__tsan_func_entry", Attr,
                                        IRB.getVoidTy(), IRB.getInt8PtrTy());
  TsanFuncExit =
      M.getOrInsertFunction("__tsan_func_exit", Attr, IRB.getVoidTy());
  TsanIgnoreBegin = M.getOrInsertFunction("__tsan_ignore_thread_begin", Attr,
                                          IRB.getVoidTy());
  TsanIgnoreEnd =
      M.getOrInsertFunction("__tsan_ignore_thread_end", Attr, IRB.getVoidTy());
  IntegerType *OrdTy = IRB.getInt32Ty();
  for (size_t i = 0; i < kNumberOfAccessSizes; ++i) {
    const unsigned ByteSize = 1U << i;
    const unsigned BitSize = ByteSize * 8;
    std::string ByteSizeStr = utostr(ByteSize);
    std::string BitSizeStr = utostr(BitSize);
    SmallString<32> ReadName("__tsan_read" + ByteSizeStr);
    TsanRead[i] = M.getOrInsertFunction(ReadName, Attr, IRB.getVoidTy(),
                                        IRB.getInt8PtrTy());

    SmallString<32> WriteName("__tsan_write" + ByteSizeStr);
    TsanWrite[i] = M.getOrInsertFunction(WriteName, Attr, IRB.getVoidTy(),
                                         IRB.getInt8PtrTy());

    SmallString<64> UnalignedReadName("__tsan_unaligned_read" + ByteSizeStr);
    TsanUnalignedRead[i] = M.getOrInsertFunction(
        UnalignedReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    SmallString<64> UnalignedWriteName("__tsan_unaligned_write" + ByteSizeStr);
    TsanUnalignedWrite[i] = M.getOrInsertFunction(
        UnalignedWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    SmallString<64> VolatileReadName("__tsan_volatile_read" + ByteSizeStr);
    TsanVolatileRead[i] = M.getOrInsertFunction(
        VolatileReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    SmallString<64> VolatileWriteName("__tsan_volatile_write" + ByteSizeStr);
    TsanVolatileWrite[i] = M.getOrInsertFunction(
        VolatileWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    SmallString<64> UnalignedVolatileReadName("__tsan_unaligned_volatile_read" +
                                              ByteSizeStr);
    TsanUnalignedVolatileRead[i] = M.getOrInsertFunction(
        UnalignedVolatileReadName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    SmallString<64> UnalignedVolatileWriteName(
        "__tsan_unaligned_volatile_write" + ByteSizeStr);
    TsanUnalignedVolatileWrite[i] = M.getOrInsertFunction(
        UnalignedVolatileWriteName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    SmallString<64> CompoundRWName("__tsan_read_write" + ByteSizeStr);
    TsanCompoundRW[i] = M.getOrInsertFunction(
        CompoundRWName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    SmallString<64> UnalignedCompoundRWName("__tsan_unaligned_read_write" +
                                            ByteSizeStr);
    TsanUnalignedCompoundRW[i] = M.getOrInsertFunction(
        UnalignedCompoundRWName, Attr, IRB.getVoidTy(), IRB.getInt8PtrTy());

    Type *Ty = Type::getIntNTy(M.getContext(), BitSize);
    Type *PtrTy = Ty->getPointerTo();
    SmallString<32> AtomicLoadName("__tsan_atomic" + BitSizeStr + "_load");
    {
      AttributeList AL = Attr;
      AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
      TsanAtomicLoad[i] =
          M.getOrInsertFunction(AtomicLoadName, AL, Ty, PtrTy, OrdTy);
    }

    SmallString<32> AtomicStoreName("__tsan_atomic" + BitSizeStr + "_store");
    {
      AttributeList AL = Attr;
      AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
      AL = AL.addParamAttribute(M.getContext(), 2, Attribute::ZExt);
      TsanAtomicStore[i] = M.getOrInsertFunction(
          AtomicStoreName, AL, IRB.getVoidTy(), PtrTy, Ty, OrdTy);
    }

    for (unsigned Op = AtomicRMWInst::FIRST_BINOP;
         Op <= AtomicRMWInst::LAST_BINOP; ++Op) {
      TsanAtomicRMW[Op][i] = nullptr;
      const char *NamePart = nullptr;
      if (Op == AtomicRMWInst::Xchg)
        NamePart = "_exchange";
      else if (Op == AtomicRMWInst::Add)
        NamePart = "_fetch_add";
      else if (Op == AtomicRMWInst::Sub)
        NamePart = "_fetch_sub";
      else if (Op == AtomicRMWInst::And)
        NamePart = "_fetch_and";
      else if (Op == AtomicRMWInst::Or)
        NamePart = "_fetch_or";
      else if (Op == AtomicRMWInst::Xor)
        NamePart = "_fetch_xor";
      else if (Op == AtomicRMWInst::Nand)
        NamePart = "_fetch_nand";
      else
        continue;
      SmallString<32> RMWName("__tsan_atomic" + itostr(BitSize) + NamePart);
      {
        AttributeList AL = Attr;
        AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
        AL = AL.addParamAttribute(M.getContext(), 2, Attribute::ZExt);
        TsanAtomicRMW[Op][i] =
            M.getOrInsertFunction(RMWName, AL, Ty, PtrTy, Ty, OrdTy);
      }
    }

    SmallString<32> AtomicCASName("__tsan_atomic" + BitSizeStr +
                                  "_compare_exchange_val");
    {
      AttributeList AL = Attr;
      AL = AL.addParamAttribute(M.getContext(), 1, Attribute::ZExt);
      AL = AL.addParamAttribute(M.getContext(), 2, Attribute::ZExt);
      AL = AL.addParamAttribute(M.getContext(), 3, Attribute::ZExt);
      AL = AL.addParamAttribute(M.getContext(), 4, Attribute::ZExt);
      TsanAtomicCAS[i] = M.getOrInsertFunction(AtomicCASName, AL, Ty, PtrTy, Ty,
                                               Ty, OrdTy, OrdTy);
    }
  }
  TsanVptrUpdate =
      M.getOrInsertFunction("__tsan_vptr_update", Attr, IRB.getVoidTy(),
                            IRB.getInt8PtrTy(), IRB.getInt8PtrTy());
  TsanVptrLoad = M.getOrInsertFunction("__tsan_vptr_read", Attr,
                                       IRB.getVoidTy(), IRB.getInt8PtrTy());
  {
    AttributeList AL = Attr;
    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
    TsanAtomicThreadFence = M.getOrInsertFunction("__tsan_atomic_thread_fence",
                                                  AL, IRB.getVoidTy(), OrdTy);
  }
  {
    AttributeList AL = Attr;
    AL = AL.addParamAttribute(M.getContext(), 0, Attribute::ZExt);
    TsanAtomicSignalFence = M.getOrInsertFunction("__tsan_atomic_signal_fence",
                                                  AL, IRB.getVoidTy(), OrdTy);
  }

  MemmoveFn =
      M.getOrInsertFunction("memmove", Attr, IRB.getInt8PtrTy(),
                            IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy);
  MemcpyFn =
      M.getOrInsertFunction("memcpy", Attr, IRB.getInt8PtrTy(),
                            IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy);
  MemsetFn =
      M.getOrInsertFunction("memset", Attr, IRB.getInt8PtrTy(),
                            IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy);
}

static bool isVtableAccess(Instruction *I) {
  if (MDNode *Tag = I->getMetadata(LLVMContext::MD_tbaa))
    return Tag->isTBAAVtableAccess();
  return false;
}

// Do not instrument known races/"benign races" that come from compiler
// instrumentatin. The user has no way of suppressing them.
static bool shouldInstrumentReadWriteFromAddress(const Module *M, Value *Addr) {
  // Peel off GEPs and BitCasts.
  Addr = Addr->stripInBoundsOffsets();

  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
    if (GV->hasSection()) {
      StringRef SectionName = GV->getSection();
      // Check if the global is in the PGO counters section.
      auto OF = Triple(M->getTargetTriple()).getObjectFormat();
      if (SectionName.endswith(
              getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false)))
        return false;
    }

    // Check if the global is private gcov data.
    if (GV->getName().startswith("__llvm_gcov") ||
        GV->getName().startswith("__llvm_gcda"))
      return false;
  }

  // Do not instrument acesses from different address spaces; we cannot deal
  // with them.
  if (Addr) {
    Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
    if (PtrTy->getPointerAddressSpace() != 0)
      return false;
  }

  return true;
}

bool ThreadSanitizer::addrPointsToConstantData(Value *Addr) {
  // If this is a GEP, just analyze its pointer operand.
  if (GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Addr))
    Addr = GEP->getPointerOperand();

  if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
    if (GV->isConstant()) {
      // Reads from constant globals can not race with any writes.
      NumOmittedReadsFromConstantGlobals++;
      return true;
    }
  } else if (LoadInst *L = dyn_cast<LoadInst>(Addr)) {
    if (isVtableAccess(L)) {
      // Reads from a vtable pointer can not race with any writes.
      NumOmittedReadsFromVtable++;
      return true;
    }
  }
  return false;
}

// Instrumenting some of the accesses may be proven redundant.
// Currently handled:
//  - read-before-write (within same BB, no calls between)
//  - not captured variables
//
// We do not handle some of the patterns that should not survive
// after the classic compiler optimizations.
// E.g. two reads from the same temp should be eliminated by CSE,
// two writes should be eliminated by DSE, etc.
//
// 'Local' is a vector of insns within the same BB (no calls between).
// 'All' is a vector of insns that will be instrumented.
void ThreadSanitizer::chooseInstructionsToInstrument(
    SmallVectorImpl<Instruction *> &Local,
    SmallVectorImpl<InstructionInfo> &All, const DataLayout &DL) {
  DenseMap<Value *, size_t> WriteTargets; // Map of addresses to index in All
  // Iterate from the end.
  for (Instruction *I : reverse(Local)) {
    const bool IsWrite = isa<StoreInst>(*I);
    Value *Addr = IsWrite ? cast<StoreInst>(I)->getPointerOperand()
                          : cast<LoadInst>(I)->getPointerOperand();

    if (!shouldInstrumentReadWriteFromAddress(I->getModule(), Addr))
      continue;

    if (!IsWrite) {
      const auto WriteEntry = WriteTargets.find(Addr);
      if (!ClInstrumentReadBeforeWrite && WriteEntry != WriteTargets.end()) {
        auto &WI = All[WriteEntry->second];
        // If we distinguish volatile accesses and if either the read or write
        // is volatile, do not omit any instrumentation.
        const bool AnyVolatile =
            ClDistinguishVolatile && (cast<LoadInst>(I)->isVolatile() ||
                                      cast<StoreInst>(WI.Inst)->isVolatile());
        if (!AnyVolatile) {
          // We will write to this temp, so no reason to analyze the read.
          // Mark the write instruction as compound.
          WI.Flags |= InstructionInfo::kCompoundRW;
          NumOmittedReadsBeforeWrite++;
          continue;
        }
      }

      if (addrPointsToConstantData(Addr)) {
        // Addr points to some constant data -- it can not race with any writes.
        continue;
      }
    }

    if (isa<AllocaInst>(getUnderlyingObject(Addr)) &&
        !PointerMayBeCaptured(Addr, true, true)) {
      // The variable is addressable but not captured, so it cannot be
      // referenced from a different thread and participate in a data race
      // (see llvm/Analysis/CaptureTracking.h for details).
      NumOmittedNonCaptured++;
      continue;
    }

    // Instrument this instruction.
    All.emplace_back(I);
    if (IsWrite) {
      // For read-before-write and compound instrumentation we only need one
      // write target, and we can override any previous entry if it exists.
      WriteTargets[Addr] = All.size() - 1;
    }
  }
  Local.clear();
}

static bool isAtomic(Instruction *I) {
  // TODO: Ask TTI whether synchronization scope is between threads.
  if (LoadInst *LI = dyn_cast<LoadInst>(I))
    return LI->isAtomic() && LI->getSyncScopeID() != SyncScope::SingleThread;
  if (StoreInst *SI = dyn_cast<StoreInst>(I))
    return SI->isAtomic() && SI->getSyncScopeID() != SyncScope::SingleThread;
  if (isa<AtomicRMWInst>(I))
    return true;
  if (isa<AtomicCmpXchgInst>(I))
    return true;
  if (isa<FenceInst>(I))
    return true;
  return false;
}

void ThreadSanitizer::InsertRuntimeIgnores(Function &F) {
  IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
  IRB.CreateCall(TsanIgnoreBegin);
  EscapeEnumerator EE(F, "tsan_ignore_cleanup", ClHandleCxxExceptions);
  while (IRBuilder<> *AtExit = EE.Next()) {
    AtExit->CreateCall(TsanIgnoreEnd);
  }
}

bool ThreadSanitizer::sanitizeFunction(Function &F,
                                       const TargetLibraryInfo &TLI) {
  // This is required to prevent instrumenting call to __tsan_init from within
  // the module constructor.
  if (F.getName() == kTsanModuleCtorName)
    return false;
  // Naked functions can not have prologue/epilogue
  // (__tsan_func_entry/__tsan_func_exit) generated, so don't instrument them at
  // all.
  if (F.hasFnAttribute(Attribute::Naked))
    return false;

  // __attribute__(disable_sanitizer_instrumentation) prevents all kinds of
  // instrumentation.
  if (F.hasFnAttribute(Attribute::DisableSanitizerInstrumentation))
    return false;

  initialize(*F.getParent());
  SmallVector<InstructionInfo, 8> AllLoadsAndStores;
  SmallVector<Instruction*, 8> LocalLoadsAndStores;
  SmallVector<Instruction*, 8> AtomicAccesses;
  SmallVector<Instruction*, 8> MemIntrinCalls;
  bool Res = false;
  bool HasCalls = false;
  bool SanitizeFunction = F.hasFnAttribute(Attribute::SanitizeThread);
  const DataLayout &DL = F.getParent()->getDataLayout();

  // Traverse all instructions, collect loads/stores/returns, check for calls.
  for (auto &BB : F) {
    for (auto &Inst : BB) {
      if (isAtomic(&Inst))
        AtomicAccesses.push_back(&Inst);
      else if (isa<LoadInst>(Inst) || isa<StoreInst>(Inst))
        LocalLoadsAndStores.push_back(&Inst);
      else if ((isa<CallInst>(Inst) && !isa<DbgInfoIntrinsic>(Inst)) ||
               isa<InvokeInst>(Inst)) {
        if (CallInst *CI = dyn_cast<CallInst>(&Inst))
          maybeMarkSanitizerLibraryCallNoBuiltin(CI, &TLI);
        if (isa<MemIntrinsic>(Inst))
          MemIntrinCalls.push_back(&Inst);
        HasCalls = true;
        chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores,
                                       DL);
      }
    }
    chooseInstructionsToInstrument(LocalLoadsAndStores, AllLoadsAndStores, DL);
  }

  // We have collected all loads and stores.
  // FIXME: many of these accesses do not need to be checked for races
  // (e.g. variables that do not escape, etc).

  // Instrument memory accesses only if we want to report bugs in the function.
  if (ClInstrumentMemoryAccesses && SanitizeFunction)
    for (const auto &II : AllLoadsAndStores) {
      Res |= instrumentLoadOrStore(II, DL);
    }

  // Instrument atomic memory accesses in any case (they can be used to
  // implement synchronization).
  if (ClInstrumentAtomics)
    for (auto Inst : AtomicAccesses) {
      Res |= instrumentAtomic(Inst, DL);
    }

  if (ClInstrumentMemIntrinsics && SanitizeFunction)
    for (auto Inst : MemIntrinCalls) {
      Res |= instrumentMemIntrinsic(Inst);
    }

  if (F.hasFnAttribute("sanitize_thread_no_checking_at_run_time")) {
    assert(!F.hasFnAttribute(Attribute::SanitizeThread));
    if (HasCalls)
      InsertRuntimeIgnores(F);
  }

  // Instrument function entry/exit points if there were instrumented accesses.
  if ((Res || HasCalls) && ClInstrumentFuncEntryExit) {
    IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI());
    Value *ReturnAddress = IRB.CreateCall(
        Intrinsic::getDeclaration(F.getParent(), Intrinsic::returnaddress),
        IRB.getInt32(0));
    IRB.CreateCall(TsanFuncEntry, ReturnAddress);

    EscapeEnumerator EE(F, "tsan_cleanup", ClHandleCxxExceptions);
    while (IRBuilder<> *AtExit = EE.Next()) {
      AtExit->CreateCall(TsanFuncExit, {});
    }
    Res = true;
  }
  return Res;
}

bool ThreadSanitizer::instrumentLoadOrStore(const InstructionInfo &II,
                                            const DataLayout &DL) {
  IRBuilder<> IRB(II.Inst);
  const bool IsWrite = isa<StoreInst>(*II.Inst);
  Value *Addr = IsWrite ? cast<StoreInst>(II.Inst)->getPointerOperand()
                        : cast<LoadInst>(II.Inst)->getPointerOperand();
  Type *OrigTy = getLoadStoreType(II.Inst);

  // swifterror memory addresses are mem2reg promoted by instruction selection.
  // As such they cannot have regular uses like an instrumentation function and
  // it makes no sense to track them as memory.
  if (Addr->isSwiftError())
    return false;

  int Idx = getMemoryAccessFuncIndex(OrigTy, Addr, DL);
  if (Idx < 0)
    return false;
  if (IsWrite && isVtableAccess(II.Inst)) {
    LLVM_DEBUG(dbgs() << "  VPTR : " << *II.Inst << "\n");
    Value *StoredValue = cast<StoreInst>(II.Inst)->getValueOperand();
    // StoredValue may be a vector type if we are storing several vptrs at once.
    // In this case, just take the first element of the vector since this is
    // enough to find vptr races.
    if (isa<VectorType>(StoredValue->getType()))
      StoredValue = IRB.CreateExtractElement(
          StoredValue, ConstantInt::get(IRB.getInt32Ty(), 0));
    if (StoredValue->getType()->isIntegerTy())
      StoredValue = IRB.CreateIntToPtr(StoredValue, IRB.getInt8PtrTy());
    // Call TsanVptrUpdate.
    IRB.CreateCall(TsanVptrUpdate,
                   {IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
                    IRB.CreatePointerCast(StoredValue, IRB.getInt8PtrTy())});
    NumInstrumentedVtableWrites++;
    return true;
  }
  if (!IsWrite && isVtableAccess(II.Inst)) {
    IRB.CreateCall(TsanVptrLoad,
                   IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
    NumInstrumentedVtableReads++;
    return true;
  }

  const unsigned Alignment = IsWrite ? cast<StoreInst>(II.Inst)->getAlignment()
                                     : cast<LoadInst>(II.Inst)->getAlignment();
  const bool IsCompoundRW =
      ClCompoundReadBeforeWrite && (II.Flags & InstructionInfo::kCompoundRW);
  const bool IsVolatile = ClDistinguishVolatile &&
                          (IsWrite ? cast<StoreInst>(II.Inst)->isVolatile()
                                   : cast<LoadInst>(II.Inst)->isVolatile());
  assert((!IsVolatile || !IsCompoundRW) && "Compound volatile invalid!");

  const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
  FunctionCallee OnAccessFunc = nullptr;
  if (Alignment == 0 || Alignment >= 8 || (Alignment % (TypeSize / 8)) == 0) {
    if (IsCompoundRW)
      OnAccessFunc = TsanCompoundRW[Idx];
    else if (IsVolatile)
      OnAccessFunc = IsWrite ? TsanVolatileWrite[Idx] : TsanVolatileRead[Idx];
    else
      OnAccessFunc = IsWrite ? TsanWrite[Idx] : TsanRead[Idx];
  } else {
    if (IsCompoundRW)
      OnAccessFunc = TsanUnalignedCompoundRW[Idx];
    else if (IsVolatile)
      OnAccessFunc = IsWrite ? TsanUnalignedVolatileWrite[Idx]
                             : TsanUnalignedVolatileRead[Idx];
    else
      OnAccessFunc = IsWrite ? TsanUnalignedWrite[Idx] : TsanUnalignedRead[Idx];
  }
  IRB.CreateCall(OnAccessFunc, IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
  if (IsCompoundRW || IsWrite)
    NumInstrumentedWrites++;
  if (IsCompoundRW || !IsWrite)
    NumInstrumentedReads++;
  return true;
}

static ConstantInt *createOrdering(IRBuilder<> *IRB, AtomicOrdering ord) {
  uint32_t v = 0;
  switch (ord) {
    case AtomicOrdering::NotAtomic:
      llvm_unreachable("unexpected atomic ordering!");
    case AtomicOrdering::Unordered:              LLVM_FALLTHROUGH;
    case AtomicOrdering::Monotonic:              v = 0; break;
    // Not specified yet:
    // case AtomicOrdering::Consume:                v = 1; break;
    case AtomicOrdering::Acquire:                v = 2; break;
    case AtomicOrdering::Release:                v = 3; break;
    case AtomicOrdering::AcquireRelease:         v = 4; break;
    case AtomicOrdering::SequentiallyConsistent: v = 5; break;
  }
  return IRB->getInt32(v);
}

// If a memset intrinsic gets inlined by the code gen, we will miss races on it.
// So, we either need to ensure the intrinsic is not inlined, or instrument it.
// We do not instrument memset/memmove/memcpy intrinsics (too complicated),
// instead we simply replace them with regular function calls, which are then
// intercepted by the run-time.
// Since tsan is running after everyone else, the calls should not be
// replaced back with intrinsics. If that becomes wrong at some point,
// we will need to call e.g. __tsan_memset to avoid the intrinsics.
bool ThreadSanitizer::instrumentMemIntrinsic(Instruction *I) {
  IRBuilder<> IRB(I);
  if (MemSetInst *M = dyn_cast<MemSetInst>(I)) {
    IRB.CreateCall(
        MemsetFn,
        {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
         IRB.CreateIntCast(M->getArgOperand(1), IRB.getInt32Ty(), false),
         IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
    I->eraseFromParent();
  } else if (MemTransferInst *M = dyn_cast<MemTransferInst>(I)) {
    IRB.CreateCall(
        isa<MemCpyInst>(M) ? MemcpyFn : MemmoveFn,
        {IRB.CreatePointerCast(M->getArgOperand(0), IRB.getInt8PtrTy()),
         IRB.CreatePointerCast(M->getArgOperand(1), IRB.getInt8PtrTy()),
         IRB.CreateIntCast(M->getArgOperand(2), IntptrTy, false)});
    I->eraseFromParent();
  }
  return false;
}

// Both llvm and ThreadSanitizer atomic operations are based on C++11/C1x
// standards.  For background see C++11 standard.  A slightly older, publicly
// available draft of the standard (not entirely up-to-date, but close enough
// for casual browsing) is available here:
// http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2011/n3242.pdf
// The following page contains more background information:
// http://www.hpl.hp.com/personal/Hans_Boehm/c++mm/

bool ThreadSanitizer::instrumentAtomic(Instruction *I, const DataLayout &DL) {
  IRBuilder<> IRB(I);
  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
    Value *Addr = LI->getPointerOperand();
    Type *OrigTy = LI->getType();
    int Idx = getMemoryAccessFuncIndex(OrigTy, Addr, DL);
    if (Idx < 0)
      return false;
    const unsigned ByteSize = 1U << Idx;
    const unsigned BitSize = ByteSize * 8;
    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
    Type *PtrTy = Ty->getPointerTo();
    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
                     createOrdering(&IRB, LI->getOrdering())};
    Value *C = IRB.CreateCall(TsanAtomicLoad[Idx], Args);
    Value *Cast = IRB.CreateBitOrPointerCast(C, OrigTy);
    I->replaceAllUsesWith(Cast);
  } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
    Value *Addr = SI->getPointerOperand();
    int Idx =
        getMemoryAccessFuncIndex(SI->getValueOperand()->getType(), Addr, DL);
    if (Idx < 0)
      return false;
    const unsigned ByteSize = 1U << Idx;
    const unsigned BitSize = ByteSize * 8;
    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
    Type *PtrTy = Ty->getPointerTo();
    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
                     IRB.CreateBitOrPointerCast(SI->getValueOperand(), Ty),
                     createOrdering(&IRB, SI->getOrdering())};
    CallInst *C = CallInst::Create(TsanAtomicStore[Idx], Args);
    ReplaceInstWithInst(I, C);
  } else if (AtomicRMWInst *RMWI = dyn_cast<AtomicRMWInst>(I)) {
    Value *Addr = RMWI->getPointerOperand();
    int Idx =
        getMemoryAccessFuncIndex(RMWI->getValOperand()->getType(), Addr, DL);
    if (Idx < 0)
      return false;
    FunctionCallee F = TsanAtomicRMW[RMWI->getOperation()][Idx];
    if (!F)
      return false;
    const unsigned ByteSize = 1U << Idx;
    const unsigned BitSize = ByteSize * 8;
    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
    Type *PtrTy = Ty->getPointerTo();
    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
                     IRB.CreateIntCast(RMWI->getValOperand(), Ty, false),
                     createOrdering(&IRB, RMWI->getOrdering())};
    CallInst *C = CallInst::Create(F, Args);
    ReplaceInstWithInst(I, C);
  } else if (AtomicCmpXchgInst *CASI = dyn_cast<AtomicCmpXchgInst>(I)) {
    Value *Addr = CASI->getPointerOperand();
    Type *OrigOldValTy = CASI->getNewValOperand()->getType();
    int Idx = getMemoryAccessFuncIndex(OrigOldValTy, Addr, DL);
    if (Idx < 0)
      return false;
    const unsigned ByteSize = 1U << Idx;
    const unsigned BitSize = ByteSize * 8;
    Type *Ty = Type::getIntNTy(IRB.getContext(), BitSize);
    Type *PtrTy = Ty->getPointerTo();
    Value *CmpOperand =
      IRB.CreateBitOrPointerCast(CASI->getCompareOperand(), Ty);
    Value *NewOperand =
      IRB.CreateBitOrPointerCast(CASI->getNewValOperand(), Ty);
    Value *Args[] = {IRB.CreatePointerCast(Addr, PtrTy),
                     CmpOperand,
                     NewOperand,
                     createOrdering(&IRB, CASI->getSuccessOrdering()),
                     createOrdering(&IRB, CASI->getFailureOrdering())};
    CallInst *C = IRB.CreateCall(TsanAtomicCAS[Idx], Args);
    Value *Success = IRB.CreateICmpEQ(C, CmpOperand);
    Value *OldVal = C;
    if (Ty != OrigOldValTy) {
      // The value is a pointer, so we need to cast the return value.
      OldVal = IRB.CreateIntToPtr(C, OrigOldValTy);
    }

    Value *Res =
      IRB.CreateInsertValue(UndefValue::get(CASI->getType()), OldVal, 0);
    Res = IRB.CreateInsertValue(Res, Success, 1);

    I->replaceAllUsesWith(Res);
    I->eraseFromParent();
  } else if (FenceInst *FI = dyn_cast<FenceInst>(I)) {
    Value *Args[] = {createOrdering(&IRB, FI->getOrdering())};
    FunctionCallee F = FI->getSyncScopeID() == SyncScope::SingleThread
                           ? TsanAtomicSignalFence
                           : TsanAtomicThreadFence;
    CallInst *C = CallInst::Create(F, Args);
    ReplaceInstWithInst(I, C);
  }
  return true;
}

int ThreadSanitizer::getMemoryAccessFuncIndex(Type *OrigTy, Value *Addr,
                                              const DataLayout &DL) {
  assert(OrigTy->isSized());
  assert(
      cast<PointerType>(Addr->getType())->isOpaqueOrPointeeTypeMatches(OrigTy));
  uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
  if (TypeSize != 8  && TypeSize != 16 &&
      TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
    NumAccessesWithBadSize++;
    // Ignore all unusual sizes.
    return -1;
  }
  size_t Idx = countTrailingZeros(TypeSize / 8);
  assert(Idx < kNumberOfAccessSizes);
  return Idx;
}