Bug Summary

File:lib/Transforms/Instrumentation/SanitizerCoverage.cpp
Location:line 254, column 13
Description:Function call argument is an uninitialized value

Annotated Source Code

1//===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
2//
3// The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// Coverage instrumentation that works with AddressSanitizer
11// and potentially with other Sanitizers.
12//
13// We create a Guard variable with the same linkage
14// as the function and inject this code into the entry block (CoverageLevel=1)
15// or all blocks (CoverageLevel>=2):
16// if (Guard < 0) {
17// __sanitizer_cov(&Guard);
18// }
19// The accesses to Guard are atomic. The rest of the logic is
20// in __sanitizer_cov (it's fine to call it more than once).
21//
22// With CoverageLevel>=3 we also split critical edges this effectively
23// instrumenting all edges.
24//
25// CoverageLevel>=4 add indirect call profiling implented as a function call.
26//
27// This coverage implementation provides very limited data:
28// it only tells if a given function (block) was ever executed. No counters.
29// But for many use cases this is what we need and the added slowdown small.
30//
31//===----------------------------------------------------------------------===//
32
33#include "llvm/Transforms/Instrumentation.h"
34#include "llvm/ADT/ArrayRef.h"
35#include "llvm/ADT/SmallVector.h"
36#include "llvm/IR/CallSite.h"
37#include "llvm/IR/DataLayout.h"
38#include "llvm/IR/Function.h"
39#include "llvm/IR/IRBuilder.h"
40#include "llvm/IR/InlineAsm.h"
41#include "llvm/IR/LLVMContext.h"
42#include "llvm/IR/MDBuilder.h"
43#include "llvm/IR/Module.h"
44#include "llvm/IR/Type.h"
45#include "llvm/Support/CommandLine.h"
46#include "llvm/Support/Debug.h"
47#include "llvm/Support/raw_ostream.h"
48#include "llvm/Transforms/Scalar.h"
49#include "llvm/Transforms/Utils/BasicBlockUtils.h"
50#include "llvm/Transforms/Utils/ModuleUtils.h"
51
52using namespace llvm;
53
54#define DEBUG_TYPE"sancov" "sancov"
55
56static const char *const kSanCovModuleInitName = "__sanitizer_cov_module_init";
57static const char *const kSanCovName = "__sanitizer_cov";
58static const char *const kSanCovWithCheckName = "__sanitizer_cov_with_check";
59static const char *const kSanCovIndirCallName = "__sanitizer_cov_indir_call16";
60static const char *const kSanCovTraceEnter = "__sanitizer_cov_trace_func_enter";
61static const char *const kSanCovTraceBB = "__sanitizer_cov_trace_basic_block";
62static const char *const kSanCovTraceCmp = "__sanitizer_cov_trace_cmp";
63static const char *const kSanCovModuleCtorName = "sancov.module_ctor";
64static const uint64_t kSanCtorAndDtorPriority = 2;
65
66static cl::opt<int> ClCoverageLevel("sanitizer-coverage-level",
67 cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
68 "3: all blocks and critical edges, "
69 "4: above plus indirect calls"),
70 cl::Hidden, cl::init(0));
71
72static cl::opt<unsigned> ClCoverageBlockThreshold(
73 "sanitizer-coverage-block-threshold",
74 cl::desc("Use a callback with a guard check inside it if there are"
75 " more than this number of blocks."),
76 cl::Hidden, cl::init(500));
77
78static cl::opt<bool>
79 ClExperimentalTracing("sanitizer-coverage-experimental-tracing",
80 cl::desc("Experimental basic-block tracing: insert "
81 "callbacks at every basic block"),
82 cl::Hidden, cl::init(false));
83
84static cl::opt<bool>
85 ClExperimentalCMPTracing("sanitizer-coverage-experimental-trace-compares",
86 cl::desc("Experimental tracing of CMP and similar "
87 "instructions"),
88 cl::Hidden, cl::init(false));
89
90// Experimental 8-bit counters used as an additional search heuristic during
91// coverage-guided fuzzing.
92// The counters are not thread-friendly:
93// - contention on these counters may cause significant slowdown;
94// - the counter updates are racy and the results may be inaccurate.
95// They are also inaccurate due to 8-bit integer overflow.
96static cl::opt<bool> ClUse8bitCounters("sanitizer-coverage-8bit-counters",
97 cl::desc("Experimental 8-bit counters"),
98 cl::Hidden, cl::init(false));
99
100namespace {
101
102class SanitizerCoverageModule : public ModulePass {
103 public:
104 SanitizerCoverageModule(int CoverageLevel = 0)
105 : ModulePass(ID),
106 CoverageLevel(std::max(CoverageLevel, (int)ClCoverageLevel)) {}
107 bool runOnModule(Module &M) override;
108 bool runOnFunction(Function &F);
109 static char ID; // Pass identification, replacement for typeid
110 const char *getPassName() const override {
111 return "SanitizerCoverageModule";
112 }
113
114 private:
115 void InjectCoverageForIndirectCalls(Function &F,
116 ArrayRef<Instruction *> IndirCalls);
117 void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
118 bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
119 void SetNoSanitizeMetada(Instruction *I);
120 void InjectCoverageAtBlock(Function &F, BasicBlock &BB, bool UseCalls);
121 unsigned NumberOfInstrumentedBlocks() {
122 return SanCovFunction->getNumUses() + SanCovWithCheckFunction->getNumUses();
123 }
124 Function *SanCovFunction;
125 Function *SanCovWithCheckFunction;
126 Function *SanCovIndirCallFunction;
127 Function *SanCovModuleInit;
128 Function *SanCovTraceEnter, *SanCovTraceBB;
129 Function *SanCovTraceCmpFunction;
130 InlineAsm *EmptyAsm;
131 Type *IntptrTy, *Int64Ty;
132 LLVMContext *C;
133 const DataLayout *DL;
134
135 GlobalVariable *GuardArray;
136 GlobalVariable *EightBitCounterArray;
137
138 int CoverageLevel;
139};
140
141} // namespace
142
143static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
144 if (Function *F = dyn_cast<Function>(FuncOrBitcast))
145 return F;
146 std::string Err;
147 raw_string_ostream Stream(Err);
148 Stream << "SanitizerCoverage interface function redefined: "
149 << *FuncOrBitcast;
150 report_fatal_error(Err);
151}
152
153bool SanitizerCoverageModule::runOnModule(Module &M) {
154 if (!CoverageLevel) return false;
1
Taking false branch
→
155 C = &(M.getContext());
156 DL = &M.getDataLayout();
157 IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
158 Type *VoidTy = Type::getVoidTy(*C);
159 IRBuilder<> IRB(*C);
160 Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
161 Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
162 Int64Ty = IRB.getInt64Ty();
163
164 Function *CtorFunc =
165 Function::Create(FunctionType::get(VoidTy, false),
166 GlobalValue::InternalLinkage, kSanCovModuleCtorName, &M);
167 ReturnInst::Create(*C, BasicBlock::Create(*C, "", CtorFunc));
168 appendToGlobalCtors(M, CtorFunc, kSanCtorAndDtorPriority);
169
170 SanCovFunction = checkInterfaceFunction(
171 M.getOrInsertFunction(kSanCovName, VoidTy, Int32PtrTy, nullptr));
172 SanCovWithCheckFunction = checkInterfaceFunction(
173 M.getOrInsertFunction(kSanCovWithCheckName, VoidTy, Int32PtrTy, nullptr));
174 SanCovIndirCallFunction = checkInterfaceFunction(M.getOrInsertFunction(
175 kSanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
176 SanCovTraceCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
177 kSanCovTraceCmp, VoidTy, Int64Ty, Int64Ty, Int64Ty, nullptr));
178
179 SanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
180 kSanCovModuleInitName, Type::getVoidTy(*C), Int32PtrTy, IntptrTy,
181 Int8PtrTy, Int8PtrTy, nullptr));
182 SanCovModuleInit->setLinkage(Function::ExternalLinkage);
183 // We insert an empty inline asm after cov callbacks to avoid callback merge.
184 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
185 StringRef(""), StringRef(""),
186 /*hasSideEffects=*/true);
187
188 if (ClExperimentalTracing) {
2
←
Taking false branch
→
189 SanCovTraceEnter = checkInterfaceFunction(
190 M.getOrInsertFunction(kSanCovTraceEnter, VoidTy, Int32PtrTy, nullptr));
191 SanCovTraceBB = checkInterfaceFunction(
192 M.getOrInsertFunction(kSanCovTraceBB, VoidTy, Int32PtrTy, nullptr));
193 }
194
195 // At this point we create a dummy array of guards because we don't
196 // know how many elements we will need.
197 Type *Int32Ty = IRB.getInt32Ty();
198 Type *Int8Ty = IRB.getInt8Ty();
199
200 GuardArray =
201 new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage,
202 nullptr, "__sancov_gen_cov_tmp");
203 if (ClUse8bitCounters)
3
←
Taking false branch
→
204 EightBitCounterArray =
205 new GlobalVariable(M, Int8Ty, false, GlobalVariable::ExternalLinkage,
206 nullptr, "__sancov_gen_cov_tmp");
207
208 for (auto &F : M)
209 runOnFunction(F);
210
211 auto N = NumberOfInstrumentedBlocks();
212
213 // Now we know how many elements we need. Create an array of guards
214 // with one extra element at the beginning for the size.
215 Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1);
216 GlobalVariable *RealGuardArray = new GlobalVariable(
217 M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage,
218 Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov");
219
220
221 // Replace the dummy array with the real one.
222 GuardArray->replaceAllUsesWith(
223 IRB.CreatePointerCast(RealGuardArray, Int32PtrTy));
224 GuardArray->eraseFromParent();
225
226 GlobalVariable *RealEightBitCounterArray;
4
←
'RealEightBitCounterArray' declared without an initial value
→
227 if (ClUse8bitCounters) {
5
←
Taking false branch
→
228 // Make sure the array is 16-aligned.
229 static const int kCounterAlignment = 16;
230 Type *Int8ArrayNTy =
231 ArrayType::get(Int8Ty, RoundUpToAlignment(N, kCounterAlignment));
232 RealEightBitCounterArray = new GlobalVariable(
233 M, Int8ArrayNTy, false, GlobalValue::PrivateLinkage,
234 Constant::getNullValue(Int8ArrayNTy), "__sancov_gen_cov_counter");
235 RealEightBitCounterArray->setAlignment(kCounterAlignment);
236 EightBitCounterArray->replaceAllUsesWith(
237 IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy));
238 EightBitCounterArray->eraseFromParent();
239 }
240
241 // Create variable for module (compilation unit) name
242 Constant *ModNameStrConst =
243 ConstantDataArray::getString(M.getContext(), M.getName(), true);
244 GlobalVariable *ModuleName =
245 new GlobalVariable(M, ModNameStrConst->getType(), true,
246 GlobalValue::PrivateLinkage, ModNameStrConst);
247
248 // Call __sanitizer_cov_module_init
249 IRB.SetInsertPoint(CtorFunc->getEntryBlock().getTerminator());
250 IRB.CreateCall4(
251 SanCovModuleInit, IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
252 ConstantInt::get(IntptrTy, N),
253 ClUse8bitCounters
6
←
'?' condition is true
→
254 ? IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy)
7
←
Function call argument is an uninitialized value
255 : Constant::getNullValue(Int8PtrTy),
256 IRB.CreatePointerCast(ModuleName, Int8PtrTy));
257 return true;
258}
259
260bool SanitizerCoverageModule::runOnFunction(Function &F) {
261 if (F.empty()) return false;
262 if (F.getName().find(".module_ctor") != std::string::npos)
263 return false; // Should not instrument sanitizer init functions.
264 if (CoverageLevel >= 3)
265 SplitAllCriticalEdges(F);
266 SmallVector<Instruction*, 8> IndirCalls;
267 SmallVector<BasicBlock*, 16> AllBlocks;
268 SmallVector<Instruction*, 8> CmpTraceTargets;
269 for (auto &BB : F) {
270 AllBlocks.push_back(&BB);
271 for (auto &Inst : BB) {
272 if (CoverageLevel >= 4) {
273 CallSite CS(&Inst);
274 if (CS && !CS.getCalledFunction())
275 IndirCalls.push_back(&Inst);
276 }
277 if (ClExperimentalCMPTracing)
278 if (isa<ICmpInst>(&Inst))
279 CmpTraceTargets.push_back(&Inst);
280 }
281 }
282 InjectCoverage(F, AllBlocks);
283 InjectCoverageForIndirectCalls(F, IndirCalls);
284 InjectTraceForCmp(F, CmpTraceTargets);
285 return true;
286}
287
288bool SanitizerCoverageModule::InjectCoverage(Function &F,
289 ArrayRef<BasicBlock *> AllBlocks) {
290 if (!CoverageLevel) return false;
291
292 if (CoverageLevel == 1) {
293 InjectCoverageAtBlock(F, F.getEntryBlock(), false);
294 } else {
295 for (auto BB : AllBlocks)
296 InjectCoverageAtBlock(F, *BB,
297 ClCoverageBlockThreshold < AllBlocks.size());
298 }
299 return true;
300}
301
302// On every indirect call we call a run-time function
303// __sanitizer_cov_indir_call* with two parameters:
304// - callee address,
305// - global cache array that contains kCacheSize pointers (zero-initialized).
306// The cache is used to speed up recording the caller-callee pairs.
307// The address of the caller is passed implicitly via caller PC.
308// kCacheSize is encoded in the name of the run-time function.
309void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
310 Function &F, ArrayRef<Instruction *> IndirCalls) {
311 if (IndirCalls.empty()) return;
312 const int kCacheSize = 16;
313 const int kCacheAlignment = 64; // Align for better performance.
314 Type *Ty = ArrayType::get(IntptrTy, kCacheSize);
315 for (auto I : IndirCalls) {
316 IRBuilder<> IRB(I);
317 CallSite CS(I);
318 Value *Callee = CS.getCalledValue();
319 if (dyn_cast<InlineAsm>(Callee)) continue;
320 GlobalVariable *CalleeCache = new GlobalVariable(
321 *F.getParent(), Ty, false, GlobalValue::PrivateLinkage,
322 Constant::getNullValue(Ty), "__sancov_gen_callee_cache");
323 CalleeCache->setAlignment(kCacheAlignment);
324 IRB.CreateCall2(SanCovIndirCallFunction,
325 IRB.CreatePointerCast(Callee, IntptrTy),
326 IRB.CreatePointerCast(CalleeCache, IntptrTy));
327 }
328}
329
330void SanitizerCoverageModule::InjectTraceForCmp(
331 Function &F, ArrayRef<Instruction *> CmpTraceTargets) {
332 if (!ClExperimentalCMPTracing) return;
333 for (auto I : CmpTraceTargets) {
334 if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
335 IRBuilder<> IRB(ICMP);
336 Value *A0 = ICMP->getOperand(0);
337 Value *A1 = ICMP->getOperand(1);
338 if (!A0->getType()->isIntegerTy()) continue;
339 uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
340 // __sanitizer_cov_indir_call((type_size << 32) | predicate, A0, A1);
341 IRB.CreateCall3(
342 SanCovTraceCmpFunction,
343 ConstantInt::get(Int64Ty, (TypeSize << 32) | ICMP->getPredicate()),
344 IRB.CreateIntCast(A0, Int64Ty, true),
345 IRB.CreateIntCast(A1, Int64Ty, true));
346 }
347 }
348}
349
350void SanitizerCoverageModule::SetNoSanitizeMetada(Instruction *I) {
351 I->setMetadata(
352 I->getParent()->getParent()->getParent()->getMDKindID("nosanitize"),
353 MDNode::get(*C, None));
354}
355
356void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
357 bool UseCalls) {
358 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
359 // Skip static allocas at the top of the entry block so they don't become
360 // dynamic when we split the block. If we used our optimized stack layout,
361 // then there will only be one alloca and it will come first.
362 for (; IP != BE; ++IP) {
363 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
364 if (!AI || !AI->isStaticAlloca())
365 break;
366 }
367
368 bool IsEntryBB = &BB == &F.getEntryBlock();
369 DebugLoc EntryLoc = IsEntryBB && IP->getDebugLoc()
370 ? IP->getDebugLoc().getFnDebugLoc()
371 : IP->getDebugLoc();
372 IRBuilder<> IRB(IP);
373 IRB.SetCurrentDebugLocation(EntryLoc);
374 SmallVector<Value *, 1> Indices;
375 Value *GuardP = IRB.CreateAdd(
376 IRB.CreatePointerCast(GuardArray, IntptrTy),
377 ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
378 Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
379 GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
380 if (UseCalls) {
381 IRB.CreateCall(SanCovWithCheckFunction, GuardP);
382 } else {
383 LoadInst *Load = IRB.CreateLoad(GuardP);
384 Load->setAtomic(Monotonic);
385 Load->setAlignment(4);
386 SetNoSanitizeMetada(Load);
387 Value *Cmp = IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
388 Instruction *Ins = SplitBlockAndInsertIfThen(
389 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
390 IRB.SetInsertPoint(Ins);
391 IRB.SetCurrentDebugLocation(EntryLoc);
392 // __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
393 IRB.CreateCall(SanCovFunction, GuardP);
394 IRB.CreateCall(EmptyAsm); // Avoids callback merge.
395 }
396
397 if(ClUse8bitCounters) {
398 IRB.SetInsertPoint(IP);
399 Value *P = IRB.CreateAdd(
400 IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
401 ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
402 P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
403 LoadInst *LI = IRB.CreateLoad(P);
404 Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
405 StoreInst *SI = IRB.CreateStore(Inc, P);
406 SetNoSanitizeMetada(LI);
407 SetNoSanitizeMetada(SI);
408 }
409
410 if (ClExperimentalTracing) {
411 // Experimental support for tracing.
412 // Insert a callback with the same guard variable as used for coverage.
413 IRB.SetInsertPoint(IP);
414 IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
415 }
416}
417
418char SanitizerCoverageModule::ID = 0;
419INITIALIZE_PASS(SanitizerCoverageModule, "sancov",static void* initializeSanitizerCoverageModulePassOnce(PassRegistry
&Registry) { PassInfo *PI = new PassInfo("SanitizerCoverage: TODO."
"ModulePass", "sancov", & SanitizerCoverageModule ::ID, PassInfo
::NormalCtor_t(callDefaultCtor< SanitizerCoverageModule >
), false, false); Registry.registerPass(*PI, true); return PI
; } void llvm::initializeSanitizerCoverageModulePass(PassRegistry
&Registry) { static volatile sys::cas_flag initialized =
0; sys::cas_flag old_val = sys::CompareAndSwap(&initialized
, 1, 0); if (old_val == 0) { initializeSanitizerCoverageModulePassOnce
(Registry); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421, &initialized); }
420 "SanitizerCoverage: TODO."static void* initializeSanitizerCoverageModulePassOnce(PassRegistry
&Registry) { PassInfo *PI = new PassInfo("SanitizerCoverage: TODO."
"ModulePass", "sancov", & SanitizerCoverageModule ::ID, PassInfo
::NormalCtor_t(callDefaultCtor< SanitizerCoverageModule >
), false, false); Registry.registerPass(*PI, true); return PI
; } void llvm::initializeSanitizerCoverageModulePass(PassRegistry
&Registry) { static volatile sys::cas_flag initialized =
0; sys::cas_flag old_val = sys::CompareAndSwap(&initialized
, 1, 0); if (old_val == 0) { initializeSanitizerCoverageModulePassOnce
(Registry); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421, &initialized); }
421 "ModulePass", false, false)static void* initializeSanitizerCoverageModulePassOnce(PassRegistry
&Registry) { PassInfo *PI = new PassInfo("SanitizerCoverage: TODO."
"ModulePass", "sancov", & SanitizerCoverageModule ::ID, PassInfo
::NormalCtor_t(callDefaultCtor< SanitizerCoverageModule >
), false, false); Registry.registerPass(*PI, true); return PI
; } void llvm::initializeSanitizerCoverageModulePass(PassRegistry
&Registry) { static volatile sys::cas_flag initialized =
0; sys::cas_flag old_val = sys::CompareAndSwap(&initialized
, 1, 0); if (old_val == 0) { initializeSanitizerCoverageModulePassOnce
(Registry); sys::MemoryFence(); AnnotateIgnoreWritesBegin("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421); AnnotateHappensBefore("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421, &initialized); initialized = 2; AnnotateIgnoreWritesEnd
("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421); } else { sys::cas_flag tmp = initialized; sys::MemoryFence
(); while (tmp != 2) { tmp = initialized; sys::MemoryFence();
} } AnnotateHappensAfter("/tmp/buildd/llvm-toolchain-snapshot-3.7~svn233676/lib/Transforms/Instrumentation/SanitizerCoverage.cpp"
, 421, &initialized); }
422ModulePass *llvm::createSanitizerCoverageModulePass(int CoverageLevel) {
423 return new SanitizerCoverageModule(CoverageLevel);
424}