forked from OSchip/llvm-project
508 lines
20 KiB
C++
508 lines
20 KiB
C++
//===-- SanitizerCoverage.cpp - coverage instrumentation for sanitizers ---===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Coverage instrumentation that works with AddressSanitizer
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// and potentially with other Sanitizers.
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//
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// We create a Guard variable with the same linkage
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// as the function and inject this code into the entry block (SCK_Function)
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// or all blocks (SCK_BB):
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// if (Guard < 0) {
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// __sanitizer_cov(&Guard);
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// }
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// The accesses to Guard are atomic. The rest of the logic is
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// in __sanitizer_cov (it's fine to call it more than once).
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//
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// With SCK_Edge we also split critical edges this effectively
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// instrumenting all edges.
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//
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// This coverage implementation provides very limited data:
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// it only tells if a given function (block) was ever executed. No counters.
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// But for many use cases this is what we need and the added slowdown small.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Transforms/Instrumentation.h"
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#include "llvm/ADT/ArrayRef.h"
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#include "llvm/ADT/SmallVector.h"
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#include "llvm/Analysis/EHPersonalities.h"
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#include "llvm/IR/CallSite.h"
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#include "llvm/IR/DataLayout.h"
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#include "llvm/IR/DebugInfo.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/IRBuilder.h"
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#include "llvm/IR/InlineAsm.h"
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#include "llvm/IR/LLVMContext.h"
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#include "llvm/IR/MDBuilder.h"
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#include "llvm/IR/Module.h"
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#include "llvm/IR/Type.h"
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#include "llvm/Support/CommandLine.h"
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#include "llvm/Support/Debug.h"
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#include "llvm/Support/raw_ostream.h"
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#include "llvm/Transforms/Scalar.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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using namespace llvm;
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#define DEBUG_TYPE "sancov"
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static const char *const kSanCovModuleInitName = "__sanitizer_cov_module_init";
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static const char *const kSanCovName = "__sanitizer_cov";
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static const char *const kSanCovWithCheckName = "__sanitizer_cov_with_check";
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static const char *const kSanCovIndirCallName = "__sanitizer_cov_indir_call16";
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static const char *const kSanCovTraceEnter = "__sanitizer_cov_trace_func_enter";
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static const char *const kSanCovTraceBB = "__sanitizer_cov_trace_basic_block";
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static const char *const kSanCovTraceCmp = "__sanitizer_cov_trace_cmp";
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static const char *const kSanCovTraceSwitch = "__sanitizer_cov_trace_switch";
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static const char *const kSanCovModuleCtorName = "sancov.module_ctor";
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static const uint64_t kSanCtorAndDtorPriority = 2;
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static cl::opt<int> ClCoverageLevel("sanitizer-coverage-level",
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cl::desc("Sanitizer Coverage. 0: none, 1: entry block, 2: all blocks, "
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"3: all blocks and critical edges, "
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"4: above plus indirect calls"),
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cl::Hidden, cl::init(0));
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static cl::opt<unsigned> ClCoverageBlockThreshold(
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"sanitizer-coverage-block-threshold",
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cl::desc("Use a callback with a guard check inside it if there are"
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" more than this number of blocks."),
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cl::Hidden, cl::init(500));
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static cl::opt<bool>
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ClExperimentalTracing("sanitizer-coverage-experimental-tracing",
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cl::desc("Experimental basic-block tracing: insert "
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"callbacks at every basic block"),
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cl::Hidden, cl::init(false));
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static cl::opt<bool>
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ClExperimentalCMPTracing("sanitizer-coverage-experimental-trace-compares",
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cl::desc("Experimental tracing of CMP and similar "
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"instructions"),
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cl::Hidden, cl::init(false));
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// Experimental 8-bit counters used as an additional search heuristic during
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// coverage-guided fuzzing.
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// The counters are not thread-friendly:
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// - contention on these counters may cause significant slowdown;
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// - the counter updates are racy and the results may be inaccurate.
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// They are also inaccurate due to 8-bit integer overflow.
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static cl::opt<bool> ClUse8bitCounters("sanitizer-coverage-8bit-counters",
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cl::desc("Experimental 8-bit counters"),
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cl::Hidden, cl::init(false));
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namespace {
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SanitizerCoverageOptions getOptions(int LegacyCoverageLevel) {
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SanitizerCoverageOptions Res;
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switch (LegacyCoverageLevel) {
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case 0:
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Res.CoverageType = SanitizerCoverageOptions::SCK_None;
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break;
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case 1:
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Res.CoverageType = SanitizerCoverageOptions::SCK_Function;
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break;
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case 2:
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Res.CoverageType = SanitizerCoverageOptions::SCK_BB;
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break;
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case 3:
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Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
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break;
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case 4:
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Res.CoverageType = SanitizerCoverageOptions::SCK_Edge;
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Res.IndirectCalls = true;
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break;
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}
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return Res;
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}
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SanitizerCoverageOptions OverrideFromCL(SanitizerCoverageOptions Options) {
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// Sets CoverageType and IndirectCalls.
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SanitizerCoverageOptions CLOpts = getOptions(ClCoverageLevel);
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Options.CoverageType = std::max(Options.CoverageType, CLOpts.CoverageType);
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Options.IndirectCalls |= CLOpts.IndirectCalls;
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Options.TraceBB |= ClExperimentalTracing;
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Options.TraceCmp |= ClExperimentalCMPTracing;
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Options.Use8bitCounters |= ClUse8bitCounters;
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return Options;
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}
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class SanitizerCoverageModule : public ModulePass {
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public:
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SanitizerCoverageModule(
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const SanitizerCoverageOptions &Options = SanitizerCoverageOptions())
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: ModulePass(ID), Options(OverrideFromCL(Options)) {}
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bool runOnModule(Module &M) override;
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bool runOnFunction(Function &F);
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static char ID; // Pass identification, replacement for typeid
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const char *getPassName() const override {
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return "SanitizerCoverageModule";
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}
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private:
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void InjectCoverageForIndirectCalls(Function &F,
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ArrayRef<Instruction *> IndirCalls);
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void InjectTraceForCmp(Function &F, ArrayRef<Instruction *> CmpTraceTargets);
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void InjectTraceForSwitch(Function &F,
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ArrayRef<Instruction *> SwitchTraceTargets);
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bool InjectCoverage(Function &F, ArrayRef<BasicBlock *> AllBlocks);
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void SetNoSanitizeMetadata(Instruction *I);
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void InjectCoverageAtBlock(Function &F, BasicBlock &BB, bool UseCalls);
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unsigned NumberOfInstrumentedBlocks() {
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return SanCovFunction->getNumUses() +
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SanCovWithCheckFunction->getNumUses() + SanCovTraceBB->getNumUses() +
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SanCovTraceEnter->getNumUses();
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}
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Function *SanCovFunction;
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Function *SanCovWithCheckFunction;
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Function *SanCovIndirCallFunction;
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Function *SanCovTraceEnter, *SanCovTraceBB;
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Function *SanCovTraceCmpFunction;
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Function *SanCovTraceSwitchFunction;
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InlineAsm *EmptyAsm;
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Type *IntptrTy, *Int64Ty, *Int64PtrTy;
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Module *CurModule;
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LLVMContext *C;
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const DataLayout *DL;
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GlobalVariable *GuardArray;
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GlobalVariable *EightBitCounterArray;
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SanitizerCoverageOptions Options;
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};
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} // namespace
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bool SanitizerCoverageModule::runOnModule(Module &M) {
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if (Options.CoverageType == SanitizerCoverageOptions::SCK_None)
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return false;
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C = &(M.getContext());
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DL = &M.getDataLayout();
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CurModule = &M;
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IntptrTy = Type::getIntNTy(*C, DL->getPointerSizeInBits());
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Type *VoidTy = Type::getVoidTy(*C);
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IRBuilder<> IRB(*C);
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Type *Int8PtrTy = PointerType::getUnqual(IRB.getInt8Ty());
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Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
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Int64PtrTy = PointerType::getUnqual(IRB.getInt64Ty());
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Int64Ty = IRB.getInt64Ty();
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SanCovFunction = checkSanitizerInterfaceFunction(
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M.getOrInsertFunction(kSanCovName, VoidTy, Int32PtrTy, nullptr));
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SanCovWithCheckFunction = checkSanitizerInterfaceFunction(
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M.getOrInsertFunction(kSanCovWithCheckName, VoidTy, Int32PtrTy, nullptr));
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SanCovIndirCallFunction =
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checkSanitizerInterfaceFunction(M.getOrInsertFunction(
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kSanCovIndirCallName, VoidTy, IntptrTy, IntptrTy, nullptr));
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SanCovTraceCmpFunction =
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checkSanitizerInterfaceFunction(M.getOrInsertFunction(
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kSanCovTraceCmp, VoidTy, Int64Ty, Int64Ty, Int64Ty, nullptr));
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SanCovTraceSwitchFunction =
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checkSanitizerInterfaceFunction(M.getOrInsertFunction(
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kSanCovTraceSwitch, VoidTy, Int64Ty, Int64PtrTy, nullptr));
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// We insert an empty inline asm after cov callbacks to avoid callback merge.
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EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
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StringRef(""), StringRef(""),
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/*hasSideEffects=*/true);
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SanCovTraceEnter = checkSanitizerInterfaceFunction(
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M.getOrInsertFunction(kSanCovTraceEnter, VoidTy, Int32PtrTy, nullptr));
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SanCovTraceBB = checkSanitizerInterfaceFunction(
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M.getOrInsertFunction(kSanCovTraceBB, VoidTy, Int32PtrTy, nullptr));
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// At this point we create a dummy array of guards because we don't
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// know how many elements we will need.
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Type *Int32Ty = IRB.getInt32Ty();
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Type *Int8Ty = IRB.getInt8Ty();
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GuardArray =
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new GlobalVariable(M, Int32Ty, false, GlobalValue::ExternalLinkage,
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nullptr, "__sancov_gen_cov_tmp");
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if (Options.Use8bitCounters)
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EightBitCounterArray =
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new GlobalVariable(M, Int8Ty, false, GlobalVariable::ExternalLinkage,
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nullptr, "__sancov_gen_cov_tmp");
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for (auto &F : M)
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runOnFunction(F);
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auto N = NumberOfInstrumentedBlocks();
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// Now we know how many elements we need. Create an array of guards
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// with one extra element at the beginning for the size.
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Type *Int32ArrayNTy = ArrayType::get(Int32Ty, N + 1);
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GlobalVariable *RealGuardArray = new GlobalVariable(
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M, Int32ArrayNTy, false, GlobalValue::PrivateLinkage,
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Constant::getNullValue(Int32ArrayNTy), "__sancov_gen_cov");
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// Replace the dummy array with the real one.
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GuardArray->replaceAllUsesWith(
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IRB.CreatePointerCast(RealGuardArray, Int32PtrTy));
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GuardArray->eraseFromParent();
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GlobalVariable *RealEightBitCounterArray;
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if (Options.Use8bitCounters) {
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// Make sure the array is 16-aligned.
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static const int kCounterAlignment = 16;
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Type *Int8ArrayNTy = ArrayType::get(Int8Ty, alignTo(N, kCounterAlignment));
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RealEightBitCounterArray = new GlobalVariable(
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M, Int8ArrayNTy, false, GlobalValue::PrivateLinkage,
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Constant::getNullValue(Int8ArrayNTy), "__sancov_gen_cov_counter");
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RealEightBitCounterArray->setAlignment(kCounterAlignment);
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EightBitCounterArray->replaceAllUsesWith(
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IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy));
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EightBitCounterArray->eraseFromParent();
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}
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// Create variable for module (compilation unit) name
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Constant *ModNameStrConst =
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ConstantDataArray::getString(M.getContext(), M.getName(), true);
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GlobalVariable *ModuleName =
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new GlobalVariable(M, ModNameStrConst->getType(), true,
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GlobalValue::PrivateLinkage, ModNameStrConst);
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Function *CtorFunc;
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std::tie(CtorFunc, std::ignore) = createSanitizerCtorAndInitFunctions(
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M, kSanCovModuleCtorName, kSanCovModuleInitName,
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{Int32PtrTy, IntptrTy, Int8PtrTy, Int8PtrTy},
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{IRB.CreatePointerCast(RealGuardArray, Int32PtrTy),
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ConstantInt::get(IntptrTy, N),
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Options.Use8bitCounters
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? IRB.CreatePointerCast(RealEightBitCounterArray, Int8PtrTy)
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: Constant::getNullValue(Int8PtrTy),
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IRB.CreatePointerCast(ModuleName, Int8PtrTy)});
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appendToGlobalCtors(M, CtorFunc, kSanCtorAndDtorPriority);
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return true;
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}
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bool SanitizerCoverageModule::runOnFunction(Function &F) {
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if (F.empty()) return false;
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if (F.getName().find(".module_ctor") != std::string::npos)
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return false; // Should not instrument sanitizer init functions.
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// Don't instrument functions using SEH for now. Splitting basic blocks like
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// we do for coverage breaks WinEHPrepare.
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// FIXME: Remove this when SEH no longer uses landingpad pattern matching.
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if (F.hasPersonalityFn() &&
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isAsynchronousEHPersonality(classifyEHPersonality(F.getPersonalityFn())))
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return false;
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if (Options.CoverageType >= SanitizerCoverageOptions::SCK_Edge)
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SplitAllCriticalEdges(F);
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SmallVector<Instruction*, 8> IndirCalls;
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SmallVector<BasicBlock*, 16> AllBlocks;
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SmallVector<Instruction*, 8> CmpTraceTargets;
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SmallVector<Instruction*, 8> SwitchTraceTargets;
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for (auto &BB : F) {
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AllBlocks.push_back(&BB);
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for (auto &Inst : BB) {
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if (Options.IndirectCalls) {
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CallSite CS(&Inst);
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if (CS && !CS.getCalledFunction())
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IndirCalls.push_back(&Inst);
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}
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if (Options.TraceCmp) {
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if (isa<ICmpInst>(&Inst))
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CmpTraceTargets.push_back(&Inst);
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if (isa<SwitchInst>(&Inst))
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SwitchTraceTargets.push_back(&Inst);
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}
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}
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}
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InjectCoverage(F, AllBlocks);
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InjectCoverageForIndirectCalls(F, IndirCalls);
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InjectTraceForCmp(F, CmpTraceTargets);
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InjectTraceForSwitch(F, SwitchTraceTargets);
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return true;
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}
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bool SanitizerCoverageModule::InjectCoverage(Function &F,
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ArrayRef<BasicBlock *> AllBlocks) {
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switch (Options.CoverageType) {
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case SanitizerCoverageOptions::SCK_None:
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return false;
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case SanitizerCoverageOptions::SCK_Function:
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InjectCoverageAtBlock(F, F.getEntryBlock(), false);
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return true;
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default: {
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bool UseCalls = ClCoverageBlockThreshold < AllBlocks.size();
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for (auto BB : AllBlocks)
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InjectCoverageAtBlock(F, *BB, UseCalls);
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return true;
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}
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}
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}
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// On every indirect call we call a run-time function
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// __sanitizer_cov_indir_call* with two parameters:
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// - callee address,
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// - global cache array that contains kCacheSize pointers (zero-initialized).
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// The cache is used to speed up recording the caller-callee pairs.
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// The address of the caller is passed implicitly via caller PC.
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// kCacheSize is encoded in the name of the run-time function.
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void SanitizerCoverageModule::InjectCoverageForIndirectCalls(
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Function &F, ArrayRef<Instruction *> IndirCalls) {
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if (IndirCalls.empty()) return;
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const int kCacheSize = 16;
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const int kCacheAlignment = 64; // Align for better performance.
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Type *Ty = ArrayType::get(IntptrTy, kCacheSize);
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for (auto I : IndirCalls) {
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IRBuilder<> IRB(I);
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CallSite CS(I);
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Value *Callee = CS.getCalledValue();
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if (isa<InlineAsm>(Callee)) continue;
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GlobalVariable *CalleeCache = new GlobalVariable(
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*F.getParent(), Ty, false, GlobalValue::PrivateLinkage,
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Constant::getNullValue(Ty), "__sancov_gen_callee_cache");
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CalleeCache->setAlignment(kCacheAlignment);
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IRB.CreateCall(SanCovIndirCallFunction,
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{IRB.CreatePointerCast(Callee, IntptrTy),
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IRB.CreatePointerCast(CalleeCache, IntptrTy)});
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}
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}
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// For every switch statement we insert a call:
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// __sanitizer_cov_trace_switch(CondValue,
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// {NumCases, ValueSizeInBits, Case0Value, Case1Value, Case2Value, ... })
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void SanitizerCoverageModule::InjectTraceForSwitch(
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Function &F, ArrayRef<Instruction *> SwitchTraceTargets) {
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for (auto I : SwitchTraceTargets) {
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if (SwitchInst *SI = dyn_cast<SwitchInst>(I)) {
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IRBuilder<> IRB(I);
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SmallVector<Constant *, 16> Initializers;
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Value *Cond = SI->getCondition();
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if (Cond->getType()->getScalarSizeInBits() >
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Int64Ty->getScalarSizeInBits())
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continue;
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Initializers.push_back(ConstantInt::get(Int64Ty, SI->getNumCases()));
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Initializers.push_back(
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ConstantInt::get(Int64Ty, Cond->getType()->getScalarSizeInBits()));
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if (Cond->getType()->getScalarSizeInBits() <
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Int64Ty->getScalarSizeInBits())
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Cond = IRB.CreateIntCast(Cond, Int64Ty, false);
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for (auto It: SI->cases()) {
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Constant *C = It.getCaseValue();
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if (C->getType()->getScalarSizeInBits() <
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Int64Ty->getScalarSizeInBits())
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C = ConstantExpr::getCast(CastInst::ZExt, It.getCaseValue(), Int64Ty);
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Initializers.push_back(C);
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}
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ArrayType *ArrayOfInt64Ty = ArrayType::get(Int64Ty, Initializers.size());
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GlobalVariable *GV = new GlobalVariable(
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*CurModule, ArrayOfInt64Ty, false, GlobalVariable::InternalLinkage,
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ConstantArray::get(ArrayOfInt64Ty, Initializers),
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"__sancov_gen_cov_switch_values");
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IRB.CreateCall(SanCovTraceSwitchFunction,
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{Cond, IRB.CreatePointerCast(GV, Int64PtrTy)});
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}
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}
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}
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void SanitizerCoverageModule::InjectTraceForCmp(
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Function &F, ArrayRef<Instruction *> CmpTraceTargets) {
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for (auto I : CmpTraceTargets) {
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if (ICmpInst *ICMP = dyn_cast<ICmpInst>(I)) {
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IRBuilder<> IRB(ICMP);
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Value *A0 = ICMP->getOperand(0);
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Value *A1 = ICMP->getOperand(1);
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if (!A0->getType()->isIntegerTy()) continue;
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uint64_t TypeSize = DL->getTypeStoreSizeInBits(A0->getType());
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// __sanitizer_cov_trace_cmp((type_size << 32) | predicate, A0, A1);
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IRB.CreateCall(
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SanCovTraceCmpFunction,
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{ConstantInt::get(Int64Ty, (TypeSize << 32) | ICMP->getPredicate()),
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IRB.CreateIntCast(A0, Int64Ty, true),
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IRB.CreateIntCast(A1, Int64Ty, true)});
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}
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}
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}
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void SanitizerCoverageModule::SetNoSanitizeMetadata(Instruction *I) {
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I->setMetadata(
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I->getModule()->getMDKindID("nosanitize"), MDNode::get(*C, None));
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}
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void SanitizerCoverageModule::InjectCoverageAtBlock(Function &F, BasicBlock &BB,
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bool UseCalls) {
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// Don't insert coverage for unreachable blocks: we will never call
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// __sanitizer_cov() for them, so counting them in
|
|
// NumberOfInstrumentedBlocks() might complicate calculation of code coverage
|
|
// percentage. Also, unreachable instructions frequently have no debug
|
|
// locations.
|
|
if (isa<UnreachableInst>(BB.getTerminator()))
|
|
return;
|
|
BasicBlock::iterator IP = BB.getFirstInsertionPt();
|
|
|
|
bool IsEntryBB = &BB == &F.getEntryBlock();
|
|
DebugLoc EntryLoc;
|
|
if (IsEntryBB) {
|
|
if (auto SP = getDISubprogram(&F))
|
|
EntryLoc = DebugLoc::get(SP->getScopeLine(), 0, SP);
|
|
// Keep static allocas and llvm.localescape calls in the entry block. Even
|
|
// if we aren't splitting the block, it's nice for allocas to be before
|
|
// calls.
|
|
IP = PrepareToSplitEntryBlock(BB, IP);
|
|
} else {
|
|
EntryLoc = IP->getDebugLoc();
|
|
}
|
|
|
|
IRBuilder<> IRB(&*IP);
|
|
IRB.SetCurrentDebugLocation(EntryLoc);
|
|
Value *GuardP = IRB.CreateAdd(
|
|
IRB.CreatePointerCast(GuardArray, IntptrTy),
|
|
ConstantInt::get(IntptrTy, (1 + NumberOfInstrumentedBlocks()) * 4));
|
|
Type *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
|
|
GuardP = IRB.CreateIntToPtr(GuardP, Int32PtrTy);
|
|
if (Options.TraceBB) {
|
|
IRB.CreateCall(IsEntryBB ? SanCovTraceEnter : SanCovTraceBB, GuardP);
|
|
} else if (UseCalls) {
|
|
IRB.CreateCall(SanCovWithCheckFunction, GuardP);
|
|
} else {
|
|
LoadInst *Load = IRB.CreateLoad(GuardP);
|
|
Load->setAtomic(Monotonic);
|
|
Load->setAlignment(4);
|
|
SetNoSanitizeMetadata(Load);
|
|
Value *Cmp = IRB.CreateICmpSGE(Constant::getNullValue(Load->getType()), Load);
|
|
Instruction *Ins = SplitBlockAndInsertIfThen(
|
|
Cmp, &*IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
|
|
IRB.SetInsertPoint(Ins);
|
|
IRB.SetCurrentDebugLocation(EntryLoc);
|
|
// __sanitizer_cov gets the PC of the instruction using GET_CALLER_PC.
|
|
IRB.CreateCall(SanCovFunction, GuardP);
|
|
IRB.CreateCall(EmptyAsm, {}); // Avoids callback merge.
|
|
}
|
|
|
|
if (Options.Use8bitCounters) {
|
|
IRB.SetInsertPoint(&*IP);
|
|
Value *P = IRB.CreateAdd(
|
|
IRB.CreatePointerCast(EightBitCounterArray, IntptrTy),
|
|
ConstantInt::get(IntptrTy, NumberOfInstrumentedBlocks() - 1));
|
|
P = IRB.CreateIntToPtr(P, IRB.getInt8PtrTy());
|
|
LoadInst *LI = IRB.CreateLoad(P);
|
|
Value *Inc = IRB.CreateAdd(LI, ConstantInt::get(IRB.getInt8Ty(), 1));
|
|
StoreInst *SI = IRB.CreateStore(Inc, P);
|
|
SetNoSanitizeMetadata(LI);
|
|
SetNoSanitizeMetadata(SI);
|
|
}
|
|
}
|
|
|
|
char SanitizerCoverageModule::ID = 0;
|
|
INITIALIZE_PASS(SanitizerCoverageModule, "sancov",
|
|
"SanitizerCoverage: TODO."
|
|
"ModulePass", false, false)
|
|
ModulePass *llvm::createSanitizerCoverageModulePass(
|
|
const SanitizerCoverageOptions &Options) {
|
|
return new SanitizerCoverageModule(Options);
|
|
}
|