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[NFC][Fuzzer] Extract CreateGateBranch method. #117236

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merged 2 commits into from
Nov 22, 2024
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[NFC][Fuzzer] Extract CreateGateBranch method. #117236

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6b63903
[NFC][Fuzzer] Extract CreateGateBranch method.
thetruestblue Nov 21, 2024
2840c8b
Update SanitizerCoverage.cpp
thetruestblue Nov 21, 2024
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37 changes: 24 additions & 13 deletions llvm/lib/Transforms/Instrumentation/SanitizerCoverage.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -250,6 +250,8 @@ class ModuleSanitizerCoverage {
const char *Section);
GlobalVariable *CreatePCArray(Function &F, ArrayRef<BasicBlock *> AllBlocks);
void CreateFunctionLocalArrays(Function &F, ArrayRef<BasicBlock *> AllBlocks);
Instruction *CreateGateBranch(Function &F, Value *&FunctionGateCmp,
Instruction *I);
Value *CreateFunctionLocalGateCmp(IRBuilder<> &IRB);
void InjectCoverageAtBlock(Function &F, BasicBlock &BB, size_t Idx,
Value *&FunctionGateCmp, bool IsLeafFunc = true);
Expand Down Expand Up @@ -815,6 +817,24 @@ Value *ModuleSanitizerCoverage::CreateFunctionLocalGateCmp(IRBuilder<> &IRB) {
return Cmp;
}

Instruction *ModuleSanitizerCoverage::CreateGateBranch(Function &F,
Value *&FunctionGateCmp,
Instruction *IP) {
if (!FunctionGateCmp) {
// Create this in the entry block
BasicBlock &BB = F.getEntryBlock();
BasicBlock::iterator IP = BB.getFirstInsertionPt();
IP = PrepareToSplitEntryBlock(BB, IP);
IRBuilder<> EntryIRB(&*IP);
FunctionGateCmp = CreateFunctionLocalGateCmp(EntryIRB);
}
// Set the branch weights in order to minimize the price paid when the
// gate is turned off, allowing the default enablement of this
// instrumentation with as little of a performance cost as possible
auto Weights = MDBuilder(*C).createBranchWeights(1, 100000);
return SplitBlockAndInsertIfThen(FunctionGateCmp, IP, false, Weights);
}

bool ModuleSanitizerCoverage::InjectCoverage(Function &F,
ArrayRef<BasicBlock *> AllBlocks,
bool IsLeafFunc) {
Expand Down Expand Up @@ -1012,19 +1032,10 @@ void ModuleSanitizerCoverage::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
ConstantInt::get(IntptrTy, Idx * 4)),
PtrTy);
if (Options.GatedCallbacks) {
if (!FunctionGateCmp) {
// Create this in the entry block
assert(IsEntryBB);
FunctionGateCmp = CreateFunctionLocalGateCmp(IRB);
}
// Set the branch weights in order to minimize the price paid when the
// gate is turned off, allowing the default enablement of this
// instrumentation with as little of a performance cost as possible
auto Weights = MDBuilder(*C).createBranchWeights(1, 100000);
auto ThenTerm =
SplitBlockAndInsertIfThen(FunctionGateCmp, &*IP, false, Weights);
IRBuilder<> ThenIRB(ThenTerm);
ThenIRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
Instruction *I = &*IP;
auto GateBranch = CreateGateBranch(F, FunctionGateCmp, I);
IRBuilder<> GateIRB(GateBranch);
GateIRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
} else {
IRB.CreateCall(SanCovTracePCGuard, GuardPtr)->setCannotMerge();
}
Expand Down
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