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Diffstat (limited to 'contrib/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp')
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diff --git a/contrib/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp b/contrib/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp new file mode 100644 index 000000000000..d547adc86e1b --- /dev/null +++ b/contrib/llvm/lib/Transforms/Instrumentation/MemorySanitizer.cpp @@ -0,0 +1,2350 @@ +//===-- MemorySanitizer.cpp - detector of uninitialized reads -------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +/// \file +/// This file is a part of MemorySanitizer, a detector of uninitialized +/// reads. +/// +/// Status: early prototype. +/// +/// The algorithm of the tool is similar to Memcheck +/// (http://goo.gl/QKbem). We associate a few shadow bits with every +/// byte of the application memory, poison the shadow of the malloc-ed +/// or alloca-ed memory, load the shadow bits on every memory read, +/// propagate the shadow bits through some of the arithmetic +/// instruction (including MOV), store the shadow bits on every memory +/// write, report a bug on some other instructions (e.g. JMP) if the +/// associated shadow is poisoned. +/// +/// But there are differences too. The first and the major one: +/// compiler instrumentation instead of binary instrumentation. This +/// gives us much better register allocation, possible compiler +/// optimizations and a fast start-up. But this brings the major issue +/// as well: msan needs to see all program events, including system +/// calls and reads/writes in system libraries, so we either need to +/// compile *everything* with msan or use a binary translation +/// component (e.g. DynamoRIO) to instrument pre-built libraries. +/// Another difference from Memcheck is that we use 8 shadow bits per +/// byte of application memory and use a direct shadow mapping. This +/// greatly simplifies the instrumentation code and avoids races on +/// shadow updates (Memcheck is single-threaded so races are not a +/// concern there. Memcheck uses 2 shadow bits per byte with a slow +/// path storage that uses 8 bits per byte). +/// +/// The default value of shadow is 0, which means "clean" (not poisoned). +/// +/// Every module initializer should call __msan_init to ensure that the +/// shadow memory is ready. On error, __msan_warning is called. Since +/// parameters and return values may be passed via registers, we have a +/// specialized thread-local shadow for return values +/// (__msan_retval_tls) and parameters (__msan_param_tls). +/// +/// Origin tracking. +/// +/// MemorySanitizer can track origins (allocation points) of all uninitialized +/// values. This behavior is controlled with a flag (msan-track-origins) and is +/// disabled by default. +/// +/// Origins are 4-byte values created and interpreted by the runtime library. +/// They are stored in a second shadow mapping, one 4-byte value for 4 bytes +/// of application memory. Propagation of origins is basically a bunch of +/// "select" instructions that pick the origin of a dirty argument, if an +/// instruction has one. +/// +/// Every 4 aligned, consecutive bytes of application memory have one origin +/// value associated with them. If these bytes contain uninitialized data +/// coming from 2 different allocations, the last store wins. Because of this, +/// MemorySanitizer reports can show unrelated origins, but this is unlikely in +/// practice. +/// +/// Origins are meaningless for fully initialized values, so MemorySanitizer +/// avoids storing origin to memory when a fully initialized value is stored. +/// This way it avoids needless overwritting origin of the 4-byte region on +/// a short (i.e. 1 byte) clean store, and it is also good for performance. +/// +/// Atomic handling. +/// +/// Ideally, every atomic store of application value should update the +/// corresponding shadow location in an atomic way. Unfortunately, atomic store +/// of two disjoint locations can not be done without severe slowdown. +/// +/// Therefore, we implement an approximation that may err on the safe side. +/// In this implementation, every atomically accessed location in the program +/// may only change from (partially) uninitialized to fully initialized, but +/// not the other way around. We load the shadow _after_ the application load, +/// and we store the shadow _before_ the app store. Also, we always store clean +/// shadow (if the application store is atomic). This way, if the store-load +/// pair constitutes a happens-before arc, shadow store and load are correctly +/// ordered such that the load will get either the value that was stored, or +/// some later value (which is always clean). +/// +/// This does not work very well with Compare-And-Swap (CAS) and +/// Read-Modify-Write (RMW) operations. To follow the above logic, CAS and RMW +/// must store the new shadow before the app operation, and load the shadow +/// after the app operation. Computers don't work this way. Current +/// implementation ignores the load aspect of CAS/RMW, always returning a clean +/// value. It implements the store part as a simple atomic store by storing a +/// clean shadow. + +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "msan" + +#include "llvm/Transforms/Instrumentation.h" +#include "llvm/ADT/DepthFirstIterator.h" +#include "llvm/ADT/SmallString.h" +#include "llvm/ADT/SmallVector.h" +#include "llvm/ADT/Triple.h" +#include "llvm/ADT/ValueMap.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/IRBuilder.h" +#include "llvm/IR/InlineAsm.h" +#include "llvm/IR/IntrinsicInst.h" +#include "llvm/IR/LLVMContext.h" +#include "llvm/IR/MDBuilder.h" +#include "llvm/IR/Module.h" +#include "llvm/IR/Type.h" +#include "llvm/InstVisitor.h" +#include "llvm/Support/CommandLine.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Transforms/Utils/Local.h" +#include "llvm/Transforms/Utils/ModuleUtils.h" +#include "llvm/Transforms/Utils/SpecialCaseList.h" + +using namespace llvm; + +static const uint64_t kShadowMask32 = 1ULL << 31; +static const uint64_t kShadowMask64 = 1ULL << 46; +static const uint64_t kOriginOffset32 = 1ULL << 30; +static const uint64_t kOriginOffset64 = 1ULL << 45; +static const unsigned kMinOriginAlignment = 4; +static const unsigned kShadowTLSAlignment = 8; + +/// \brief Track origins of uninitialized values. +/// +/// Adds a section to MemorySanitizer report that points to the allocation +/// (stack or heap) the uninitialized bits came from originally. +static cl::opt<bool> ClTrackOrigins("msan-track-origins", + cl::desc("Track origins (allocation sites) of poisoned memory"), + cl::Hidden, cl::init(false)); +static cl::opt<bool> ClKeepGoing("msan-keep-going", + cl::desc("keep going after reporting a UMR"), + cl::Hidden, cl::init(false)); +static cl::opt<bool> ClPoisonStack("msan-poison-stack", + cl::desc("poison uninitialized stack variables"), + cl::Hidden, cl::init(true)); +static cl::opt<bool> ClPoisonStackWithCall("msan-poison-stack-with-call", + cl::desc("poison uninitialized stack variables with a call"), + cl::Hidden, cl::init(false)); +static cl::opt<int> ClPoisonStackPattern("msan-poison-stack-pattern", + cl::desc("poison uninitialized stack variables with the given patter"), + cl::Hidden, cl::init(0xff)); +static cl::opt<bool> ClPoisonUndef("msan-poison-undef", + cl::desc("poison undef temps"), + cl::Hidden, cl::init(true)); + +static cl::opt<bool> ClHandleICmp("msan-handle-icmp", + cl::desc("propagate shadow through ICmpEQ and ICmpNE"), + cl::Hidden, cl::init(true)); + +static cl::opt<bool> ClHandleICmpExact("msan-handle-icmp-exact", + cl::desc("exact handling of relational integer ICmp"), + cl::Hidden, cl::init(false)); + +static cl::opt<bool> ClStoreCleanOrigin("msan-store-clean-origin", + cl::desc("store origin for clean (fully initialized) values"), + cl::Hidden, cl::init(false)); + +// This flag controls whether we check the shadow of the address +// operand of load or store. Such bugs are very rare, since load from +// a garbage address typically results in SEGV, but still happen +// (e.g. only lower bits of address are garbage, or the access happens +// early at program startup where malloc-ed memory is more likely to +// be zeroed. As of 2012-08-28 this flag adds 20% slowdown. +static cl::opt<bool> ClCheckAccessAddress("msan-check-access-address", + cl::desc("report accesses through a pointer which has poisoned shadow"), + cl::Hidden, cl::init(true)); + +static cl::opt<bool> ClDumpStrictInstructions("msan-dump-strict-instructions", + cl::desc("print out instructions with default strict semantics"), + cl::Hidden, cl::init(false)); + +static cl::opt<std::string> ClBlacklistFile("msan-blacklist", + cl::desc("File containing the list of functions where MemorySanitizer " + "should not report bugs"), cl::Hidden); + +// Experimental. Wraps all indirect calls in the instrumented code with +// a call to the given function. This is needed to assist the dynamic +// helper tool (MSanDR) to regain control on transition between instrumented and +// non-instrumented code. +static cl::opt<std::string> ClWrapIndirectCalls("msan-wrap-indirect-calls", + cl::desc("Wrap indirect calls with a given function"), + cl::Hidden); + +static cl::opt<bool> ClWrapIndirectCallsFast("msan-wrap-indirect-calls-fast", + cl::desc("Do not wrap indirect calls with target in the same module"), + cl::Hidden, cl::init(true)); + +namespace { + +/// \brief An instrumentation pass implementing detection of uninitialized +/// reads. +/// +/// MemorySanitizer: instrument the code in module to find +/// uninitialized reads. +class MemorySanitizer : public FunctionPass { + public: + MemorySanitizer(bool TrackOrigins = false, + StringRef BlacklistFile = StringRef()) + : FunctionPass(ID), + TrackOrigins(TrackOrigins || ClTrackOrigins), + TD(0), + WarningFn(0), + BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile : BlacklistFile), + WrapIndirectCalls(!ClWrapIndirectCalls.empty()) {} + const char *getPassName() const { return "MemorySanitizer"; } + bool runOnFunction(Function &F); + bool doInitialization(Module &M); + static char ID; // Pass identification, replacement for typeid. + + private: + void initializeCallbacks(Module &M); + + /// \brief Track origins (allocation points) of uninitialized values. + bool TrackOrigins; + + DataLayout *TD; + LLVMContext *C; + Type *IntptrTy; + Type *OriginTy; + /// \brief Thread-local shadow storage for function parameters. + GlobalVariable *ParamTLS; + /// \brief Thread-local origin storage for function parameters. + GlobalVariable *ParamOriginTLS; + /// \brief Thread-local shadow storage for function return value. + GlobalVariable *RetvalTLS; + /// \brief Thread-local origin storage for function return value. + GlobalVariable *RetvalOriginTLS; + /// \brief Thread-local shadow storage for in-register va_arg function + /// parameters (x86_64-specific). + GlobalVariable *VAArgTLS; + /// \brief Thread-local shadow storage for va_arg overflow area + /// (x86_64-specific). + GlobalVariable *VAArgOverflowSizeTLS; + /// \brief Thread-local space used to pass origin value to the UMR reporting + /// function. + GlobalVariable *OriginTLS; + + GlobalVariable *MsandrModuleStart; + GlobalVariable *MsandrModuleEnd; + + /// \brief The run-time callback to print a warning. + Value *WarningFn; + /// \brief Run-time helper that copies origin info for a memory range. + Value *MsanCopyOriginFn; + /// \brief Run-time helper that generates a new origin value for a stack + /// allocation. + Value *MsanSetAllocaOrigin4Fn; + /// \brief Run-time helper that poisons stack on function entry. + Value *MsanPoisonStackFn; + /// \brief MSan runtime replacements for memmove, memcpy and memset. + Value *MemmoveFn, *MemcpyFn, *MemsetFn; + + /// \brief Address mask used in application-to-shadow address calculation. + /// ShadowAddr is computed as ApplicationAddr & ~ShadowMask. + uint64_t ShadowMask; + /// \brief Offset of the origin shadow from the "normal" shadow. + /// OriginAddr is computed as (ShadowAddr + OriginOffset) & ~3ULL + uint64_t OriginOffset; + /// \brief Branch weights for error reporting. + MDNode *ColdCallWeights; + /// \brief Branch weights for origin store. + MDNode *OriginStoreWeights; + /// \brief Path to blacklist file. + SmallString<64> BlacklistFile; + /// \brief The blacklist. + OwningPtr<SpecialCaseList> BL; + /// \brief An empty volatile inline asm that prevents callback merge. + InlineAsm *EmptyAsm; + + bool WrapIndirectCalls; + /// \brief Run-time wrapper for indirect calls. + Value *IndirectCallWrapperFn; + // Argument and return type of IndirectCallWrapperFn: void (*f)(void). + Type *AnyFunctionPtrTy; + + friend struct MemorySanitizerVisitor; + friend struct VarArgAMD64Helper; +}; +} // namespace + +char MemorySanitizer::ID = 0; +INITIALIZE_PASS(MemorySanitizer, "msan", + "MemorySanitizer: detects uninitialized reads.", + false, false) + +FunctionPass *llvm::createMemorySanitizerPass(bool TrackOrigins, + StringRef BlacklistFile) { + return new MemorySanitizer(TrackOrigins, BlacklistFile); +} + +/// \brief Create a non-const global initialized with the given string. +/// +/// Creates a writable global for Str so that we can pass it to the +/// run-time lib. Runtime uses first 4 bytes of the string to store the +/// frame ID, so the string needs to be mutable. +static GlobalVariable *createPrivateNonConstGlobalForString(Module &M, + StringRef Str) { + Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str); + return new GlobalVariable(M, StrConst->getType(), /*isConstant=*/false, + GlobalValue::PrivateLinkage, StrConst, ""); +} + + +/// \brief Insert extern declaration of runtime-provided functions and globals. +void MemorySanitizer::initializeCallbacks(Module &M) { + // Only do this once. + if (WarningFn) + return; + + IRBuilder<> IRB(*C); + // Create the callback. + // FIXME: this function should have "Cold" calling conv, + // which is not yet implemented. + StringRef WarningFnName = ClKeepGoing ? "__msan_warning" + : "__msan_warning_noreturn"; + WarningFn = M.getOrInsertFunction(WarningFnName, IRB.getVoidTy(), NULL); + + MsanCopyOriginFn = M.getOrInsertFunction( + "__msan_copy_origin", IRB.getVoidTy(), IRB.getInt8PtrTy(), + IRB.getInt8PtrTy(), IntptrTy, NULL); + MsanSetAllocaOrigin4Fn = M.getOrInsertFunction( + "__msan_set_alloca_origin4", IRB.getVoidTy(), IRB.getInt8PtrTy(), IntptrTy, + IRB.getInt8PtrTy(), IntptrTy, NULL); + MsanPoisonStackFn = M.getOrInsertFunction( + "__msan_poison_stack", IRB.getVoidTy(), IRB.getInt8PtrTy(), IntptrTy, NULL); + MemmoveFn = M.getOrInsertFunction( + "__msan_memmove", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), + IRB.getInt8PtrTy(), IntptrTy, NULL); + MemcpyFn = M.getOrInsertFunction( + "__msan_memcpy", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), + IntptrTy, NULL); + MemsetFn = M.getOrInsertFunction( + "__msan_memset", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IRB.getInt32Ty(), + IntptrTy, NULL); + + // Create globals. + RetvalTLS = new GlobalVariable( + M, ArrayType::get(IRB.getInt64Ty(), 8), false, + GlobalVariable::ExternalLinkage, 0, "__msan_retval_tls", 0, + GlobalVariable::InitialExecTLSModel); + RetvalOriginTLS = new GlobalVariable( + M, OriginTy, false, GlobalVariable::ExternalLinkage, 0, + "__msan_retval_origin_tls", 0, GlobalVariable::InitialExecTLSModel); + + ParamTLS = new GlobalVariable( + M, ArrayType::get(IRB.getInt64Ty(), 1000), false, + GlobalVariable::ExternalLinkage, 0, "__msan_param_tls", 0, + GlobalVariable::InitialExecTLSModel); + ParamOriginTLS = new GlobalVariable( + M, ArrayType::get(OriginTy, 1000), false, GlobalVariable::ExternalLinkage, + 0, "__msan_param_origin_tls", 0, GlobalVariable::InitialExecTLSModel); + + VAArgTLS = new GlobalVariable( + M, ArrayType::get(IRB.getInt64Ty(), 1000), false, + GlobalVariable::ExternalLinkage, 0, "__msan_va_arg_tls", 0, + GlobalVariable::InitialExecTLSModel); + VAArgOverflowSizeTLS = new GlobalVariable( + M, IRB.getInt64Ty(), false, GlobalVariable::ExternalLinkage, 0, + "__msan_va_arg_overflow_size_tls", 0, + GlobalVariable::InitialExecTLSModel); + OriginTLS = new GlobalVariable( + M, IRB.getInt32Ty(), false, GlobalVariable::ExternalLinkage, 0, + "__msan_origin_tls", 0, GlobalVariable::InitialExecTLSModel); + + // We insert an empty inline asm after __msan_report* to avoid callback merge. + EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), + StringRef(""), StringRef(""), + /*hasSideEffects=*/true); + + if (WrapIndirectCalls) { + AnyFunctionPtrTy = + PointerType::getUnqual(FunctionType::get(IRB.getVoidTy(), false)); + IndirectCallWrapperFn = M.getOrInsertFunction( + ClWrapIndirectCalls, AnyFunctionPtrTy, AnyFunctionPtrTy, NULL); + } + + if (ClWrapIndirectCallsFast) { + MsandrModuleStart = new GlobalVariable( + M, IRB.getInt32Ty(), false, GlobalValue::ExternalLinkage, + 0, "__executable_start"); + MsandrModuleStart->setVisibility(GlobalVariable::HiddenVisibility); + MsandrModuleEnd = new GlobalVariable( + M, IRB.getInt32Ty(), false, GlobalValue::ExternalLinkage, + 0, "_end"); + MsandrModuleEnd->setVisibility(GlobalVariable::HiddenVisibility); + } +} + +/// \brief Module-level initialization. +/// +/// inserts a call to __msan_init to the module's constructor list. +bool MemorySanitizer::doInitialization(Module &M) { + TD = getAnalysisIfAvailable<DataLayout>(); + if (!TD) + return false; + BL.reset(SpecialCaseList::createOrDie(BlacklistFile)); + C = &(M.getContext()); + unsigned PtrSize = TD->getPointerSizeInBits(/* AddressSpace */0); + switch (PtrSize) { + case 64: + ShadowMask = kShadowMask64; + OriginOffset = kOriginOffset64; + break; + case 32: + ShadowMask = kShadowMask32; + OriginOffset = kOriginOffset32; + break; + default: + report_fatal_error("unsupported pointer size"); + break; + } + + IRBuilder<> IRB(*C); + IntptrTy = IRB.getIntPtrTy(TD); + OriginTy = IRB.getInt32Ty(); + + ColdCallWeights = MDBuilder(*C).createBranchWeights(1, 1000); + OriginStoreWeights = MDBuilder(*C).createBranchWeights(1, 1000); + + // Insert a call to __msan_init/__msan_track_origins into the module's CTORs. + appendToGlobalCtors(M, cast<Function>(M.getOrInsertFunction( + "__msan_init", IRB.getVoidTy(), NULL)), 0); + + if (TrackOrigins) + new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage, + IRB.getInt32(TrackOrigins), "__msan_track_origins"); + + if (ClKeepGoing) + new GlobalVariable(M, IRB.getInt32Ty(), true, GlobalValue::WeakODRLinkage, + IRB.getInt32(ClKeepGoing), "__msan_keep_going"); + + return true; +} + +namespace { + +/// \brief A helper class that handles instrumentation of VarArg +/// functions on a particular platform. +/// +/// Implementations are expected to insert the instrumentation +/// necessary to propagate argument shadow through VarArg function +/// calls. Visit* methods are called during an InstVisitor pass over +/// the function, and should avoid creating new basic blocks. A new +/// instance of this class is created for each instrumented function. +struct VarArgHelper { + /// \brief Visit a CallSite. + virtual void visitCallSite(CallSite &CS, IRBuilder<> &IRB) = 0; + + /// \brief Visit a va_start call. + virtual void visitVAStartInst(VAStartInst &I) = 0; + + /// \brief Visit a va_copy call. + virtual void visitVACopyInst(VACopyInst &I) = 0; + + /// \brief Finalize function instrumentation. + /// + /// This method is called after visiting all interesting (see above) + /// instructions in a function. + virtual void finalizeInstrumentation() = 0; + + virtual ~VarArgHelper() {} +}; + +struct MemorySanitizerVisitor; + +VarArgHelper* +CreateVarArgHelper(Function &Func, MemorySanitizer &Msan, + MemorySanitizerVisitor &Visitor); + +/// This class does all the work for a given function. Store and Load +/// instructions store and load corresponding shadow and origin +/// values. Most instructions propagate shadow from arguments to their +/// return values. Certain instructions (most importantly, BranchInst) +/// test their argument shadow and print reports (with a runtime call) if it's +/// non-zero. +struct MemorySanitizerVisitor : public InstVisitor<MemorySanitizerVisitor> { + Function &F; + MemorySanitizer &MS; + SmallVector<PHINode *, 16> ShadowPHINodes, OriginPHINodes; + ValueMap<Value*, Value*> ShadowMap, OriginMap; + OwningPtr<VarArgHelper> VAHelper; + + // The following flags disable parts of MSan instrumentation based on + // blacklist contents and command-line options. + bool InsertChecks; + bool LoadShadow; + bool PoisonStack; + bool PoisonUndef; + bool CheckReturnValue; + + struct ShadowOriginAndInsertPoint { + Value *Shadow; + Value *Origin; + Instruction *OrigIns; + ShadowOriginAndInsertPoint(Value *S, Value *O, Instruction *I) + : Shadow(S), Origin(O), OrigIns(I) { } + ShadowOriginAndInsertPoint() : Shadow(0), Origin(0), OrigIns(0) { } + }; + SmallVector<ShadowOriginAndInsertPoint, 16> InstrumentationList; + SmallVector<Instruction*, 16> StoreList; + SmallVector<CallSite, 16> IndirectCallList; + + MemorySanitizerVisitor(Function &F, MemorySanitizer &MS) + : F(F), MS(MS), VAHelper(CreateVarArgHelper(F, MS, *this)) { + bool SanitizeFunction = !MS.BL->isIn(F) && F.getAttributes().hasAttribute( + AttributeSet::FunctionIndex, + Attribute::SanitizeMemory); + InsertChecks = SanitizeFunction; + LoadShadow = SanitizeFunction; + PoisonStack = SanitizeFunction && ClPoisonStack; + PoisonUndef = SanitizeFunction && ClPoisonUndef; + // FIXME: Consider using SpecialCaseList to specify a list of functions that + // must always return fully initialized values. For now, we hardcode "main". + CheckReturnValue = SanitizeFunction && (F.getName() == "main"); + + DEBUG(if (!InsertChecks) + dbgs() << "MemorySanitizer is not inserting checks into '" + << F.getName() << "'\n"); + } + + void materializeStores() { + for (size_t i = 0, n = StoreList.size(); i < n; i++) { + StoreInst& I = *dyn_cast<StoreInst>(StoreList[i]); + + IRBuilder<> IRB(&I); + Value *Val = I.getValueOperand(); + Value *Addr = I.getPointerOperand(); + Value *Shadow = I.isAtomic() ? getCleanShadow(Val) : getShadow(Val); + Value *ShadowPtr = getShadowPtr(Addr, Shadow->getType(), IRB); + + StoreInst *NewSI = + IRB.CreateAlignedStore(Shadow, ShadowPtr, I.getAlignment()); + DEBUG(dbgs() << " STORE: " << *NewSI << "\n"); + (void)NewSI; + + if (ClCheckAccessAddress) + insertShadowCheck(Addr, &I); + + if (I.isAtomic()) + I.setOrdering(addReleaseOrdering(I.getOrdering())); + + if (MS.TrackOrigins) { + unsigned Alignment = std::max(kMinOriginAlignment, I.getAlignment()); + if (ClStoreCleanOrigin || isa<StructType>(Shadow->getType())) { + IRB.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRB), + Alignment); + } else { + Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB); + + // TODO(eugenis): handle non-zero constant shadow by inserting an + // unconditional check (can not simply fail compilation as this could + // be in the dead code). + if (isa<Constant>(ConvertedShadow)) + continue; + + Value *Cmp = IRB.CreateICmpNE(ConvertedShadow, + getCleanShadow(ConvertedShadow), "_mscmp"); + Instruction *CheckTerm = + SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false, + MS.OriginStoreWeights); + IRBuilder<> IRBNew(CheckTerm); + IRBNew.CreateAlignedStore(getOrigin(Val), getOriginPtr(Addr, IRBNew), + Alignment); + } + } + } + } + + void materializeChecks() { + for (size_t i = 0, n = InstrumentationList.size(); i < n; i++) { + Value *Shadow = InstrumentationList[i].Shadow; + Instruction *OrigIns = InstrumentationList[i].OrigIns; + IRBuilder<> IRB(OrigIns); + DEBUG(dbgs() << " SHAD0 : " << *Shadow << "\n"); + Value *ConvertedShadow = convertToShadowTyNoVec(Shadow, IRB); + DEBUG(dbgs() << " SHAD1 : " << *ConvertedShadow << "\n"); + // See the comment in materializeStores(). + if (isa<Constant>(ConvertedShadow)) + continue; + Value *Cmp = IRB.CreateICmpNE(ConvertedShadow, + getCleanShadow(ConvertedShadow), "_mscmp"); + Instruction *CheckTerm = + SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), + /* Unreachable */ !ClKeepGoing, + MS.ColdCallWeights); + + IRB.SetInsertPoint(CheckTerm); + if (MS.TrackOrigins) { + Value *Origin = InstrumentationList[i].Origin; + IRB.CreateStore(Origin ? (Value*)Origin : (Value*)IRB.getInt32(0), + MS.OriginTLS); + } + CallInst *Call = IRB.CreateCall(MS.WarningFn); + Call->setDebugLoc(OrigIns->getDebugLoc()); + IRB.CreateCall(MS.EmptyAsm); + DEBUG(dbgs() << " CHECK: " << *Cmp << "\n"); + } + DEBUG(dbgs() << "DONE:\n" << F); + } + + void materializeIndirectCalls() { + for (size_t i = 0, n = IndirectCallList.size(); i < n; i++) { + CallSite CS = IndirectCallList[i]; + Instruction *I = CS.getInstruction(); + BasicBlock *B = I->getParent(); + IRBuilder<> IRB(I); + Value *Fn0 = CS.getCalledValue(); + Value *Fn = IRB.CreateBitCast(Fn0, MS.AnyFunctionPtrTy); + + if (ClWrapIndirectCallsFast) { + // Check that call target is inside this module limits. + Value *Start = + IRB.CreateBitCast(MS.MsandrModuleStart, MS.AnyFunctionPtrTy); + Value *End = IRB.CreateBitCast(MS.MsandrModuleEnd, MS.AnyFunctionPtrTy); + + Value *NotInThisModule = IRB.CreateOr(IRB.CreateICmpULT(Fn, Start), + IRB.CreateICmpUGE(Fn, End)); + + PHINode *NewFnPhi = + IRB.CreatePHI(Fn0->getType(), 2, "msandr.indirect_target"); + + Instruction *CheckTerm = SplitBlockAndInsertIfThen( + cast<Instruction>(NotInThisModule), + /* Unreachable */ false, MS.ColdCallWeights); + + IRB.SetInsertPoint(CheckTerm); + // Slow path: call wrapper function to possibly transform the call + // target. + Value *NewFn = IRB.CreateBitCast( + IRB.CreateCall(MS.IndirectCallWrapperFn, Fn), Fn0->getType()); + + NewFnPhi->addIncoming(Fn0, B); + NewFnPhi->addIncoming(NewFn, dyn_cast<Instruction>(NewFn)->getParent()); + CS.setCalledFunction(NewFnPhi); + } else { + Value *NewFn = IRB.CreateBitCast( + IRB.CreateCall(MS.IndirectCallWrapperFn, Fn), Fn0->getType()); + CS.setCalledFunction(NewFn); + } + } + } + + /// \brief Add MemorySanitizer instrumentation to a function. + bool runOnFunction() { + MS.initializeCallbacks(*F.getParent()); + if (!MS.TD) return false; + + // In the presence of unreachable blocks, we may see Phi nodes with + // incoming nodes from such blocks. Since InstVisitor skips unreachable + // blocks, such nodes will not have any shadow value associated with them. + // It's easier to remove unreachable blocks than deal with missing shadow. + removeUnreachableBlocks(F); + + // Iterate all BBs in depth-first order and create shadow instructions + // for all instructions (where applicable). + // For PHI nodes we create dummy shadow PHIs which will be finalized later. + for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()), + DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) { + BasicBlock *BB = *DI; + visit(*BB); + } + + // Finalize PHI nodes. + for (size_t i = 0, n = ShadowPHINodes.size(); i < n; i++) { + PHINode *PN = ShadowPHINodes[i]; + PHINode *PNS = cast<PHINode>(getShadow(PN)); + PHINode *PNO = MS.TrackOrigins ? cast<PHINode>(getOrigin(PN)) : 0; + size_t NumValues = PN->getNumIncomingValues(); + for (size_t v = 0; v < NumValues; v++) { + PNS->addIncoming(getShadow(PN, v), PN->getIncomingBlock(v)); + if (PNO) + PNO->addIncoming(getOrigin(PN, v), PN->getIncomingBlock(v)); + } + } + + VAHelper->finalizeInstrumentation(); + + // Delayed instrumentation of StoreInst. + // This may add new checks to be inserted later. + materializeStores(); + + // Insert shadow value checks. + materializeChecks(); + + // Wrap indirect calls. + materializeIndirectCalls(); + + return true; + } + + /// \brief Compute the shadow type that corresponds to a given Value. + Type *getShadowTy(Value *V) { + return getShadowTy(V->getType()); + } + + /// \brief Compute the shadow type that corresponds to a given Type. + Type *getShadowTy(Type *OrigTy) { + if (!OrigTy->isSized()) { + return 0; + } + // For integer type, shadow is the same as the original type. + // This may return weird-sized types like i1. + if (IntegerType *IT = dyn_cast<IntegerType>(OrigTy)) + return IT; + if (VectorType *VT = dyn_cast<VectorType>(OrigTy)) { + uint32_t EltSize = MS.TD->getTypeSizeInBits(VT->getElementType()); + return VectorType::get(IntegerType::get(*MS.C, EltSize), + VT->getNumElements()); + } + if (StructType *ST = dyn_cast<StructType>(OrigTy)) { + SmallVector<Type*, 4> Elements; + for (unsigned i = 0, n = ST->getNumElements(); i < n; i++) + Elements.push_back(getShadowTy(ST->getElementType(i))); + StructType *Res = StructType::get(*MS.C, Elements, ST->isPacked()); + DEBUG(dbgs() << "getShadowTy: " << *ST << " ===> " << *Res << "\n"); + return Res; + } + uint32_t TypeSize = MS.TD->getTypeSizeInBits(OrigTy); + return IntegerType::get(*MS.C, TypeSize); + } + + /// \brief Flatten a vector type. + Type *getShadowTyNoVec(Type *ty) { + if (VectorType *vt = dyn_cast<VectorType>(ty)) + return IntegerType::get(*MS.C, vt->getBitWidth()); + return ty; + } + + /// \brief Convert a shadow value to it's flattened variant. + Value *convertToShadowTyNoVec(Value *V, IRBuilder<> &IRB) { + Type *Ty = V->getType(); + Type *NoVecTy = getShadowTyNoVec(Ty); + if (Ty == NoVecTy) return V; + return IRB.CreateBitCast(V, NoVecTy); + } + + /// \brief Compute the shadow address that corresponds to a given application + /// address. + /// + /// Shadow = Addr & ~ShadowMask. + Value *getShadowPtr(Value *Addr, Type *ShadowTy, + IRBuilder<> &IRB) { + Value *ShadowLong = + IRB.CreateAnd(IRB.CreatePointerCast(Addr, MS.IntptrTy), + ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask)); + return IRB.CreateIntToPtr(ShadowLong, PointerType::get(ShadowTy, 0)); + } + + /// \brief Compute the origin address that corresponds to a given application + /// address. + /// + /// OriginAddr = (ShadowAddr + OriginOffset) & ~3ULL + Value *getOriginPtr(Value *Addr, IRBuilder<> &IRB) { + Value *ShadowLong = + IRB.CreateAnd(IRB.CreatePointerCast(Addr, MS.IntptrTy), + ConstantInt::get(MS.IntptrTy, ~MS.ShadowMask)); + Value *Add = + IRB.CreateAdd(ShadowLong, + ConstantInt::get(MS.IntptrTy, MS.OriginOffset)); + Value *SecondAnd = + IRB.CreateAnd(Add, ConstantInt::get(MS.IntptrTy, ~3ULL)); + return IRB.CreateIntToPtr(SecondAnd, PointerType::get(IRB.getInt32Ty(), 0)); + } + + /// \brief Compute the shadow address for a given function argument. + /// + /// Shadow = ParamTLS+ArgOffset. + Value *getShadowPtrForArgument(Value *A, IRBuilder<> &IRB, + int ArgOffset) { + Value *Base = IRB.CreatePointerCast(MS.ParamTLS, MS.IntptrTy); + Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset)); + return IRB.CreateIntToPtr(Base, PointerType::get(getShadowTy(A), 0), + "_msarg"); + } + + /// \brief Compute the origin address for a given function argument. + Value *getOriginPtrForArgument(Value *A, IRBuilder<> &IRB, + int ArgOffset) { + if (!MS.TrackOrigins) return 0; + Value *Base = IRB.CreatePointerCast(MS.ParamOriginTLS, MS.IntptrTy); + Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset)); + return IRB.CreateIntToPtr(Base, PointerType::get(MS.OriginTy, 0), + "_msarg_o"); + } + + /// \brief Compute the shadow address for a retval. + Value *getShadowPtrForRetval(Value *A, IRBuilder<> &IRB) { + Value *Base = IRB.CreatePointerCast(MS.RetvalTLS, MS.IntptrTy); + return IRB.CreateIntToPtr(Base, PointerType::get(getShadowTy(A), 0), + "_msret"); + } + + /// \brief Compute the origin address for a retval. + Value *getOriginPtrForRetval(IRBuilder<> &IRB) { + // We keep a single origin for the entire retval. Might be too optimistic. + return MS.RetvalOriginTLS; + } + + /// \brief Set SV to be the shadow value for V. + void setShadow(Value *V, Value *SV) { + assert(!ShadowMap.count(V) && "Values may only have one shadow"); + ShadowMap[V] = SV; + } + + /// \brief Set Origin to be the origin value for V. + void setOrigin(Value *V, Value *Origin) { + if (!MS.TrackOrigins) return; + assert(!OriginMap.count(V) && "Values may only have one origin"); + DEBUG(dbgs() << "ORIGIN: " << *V << " ==> " << *Origin << "\n"); + OriginMap[V] = Origin; + } + + /// \brief Create a clean shadow value for a given value. + /// + /// Clean shadow (all zeroes) means all bits of the value are defined + /// (initialized). + Constant *getCleanShadow(Value *V) { + Type *ShadowTy = getShadowTy(V); + if (!ShadowTy) + return 0; + return Constant::getNullValue(ShadowTy); + } + + /// \brief Create a dirty shadow of a given shadow type. + Constant *getPoisonedShadow(Type *ShadowTy) { + assert(ShadowTy); + if (isa<IntegerType>(ShadowTy) || isa<VectorType>(ShadowTy)) + return Constant::getAllOnesValue(ShadowTy); + StructType *ST = cast<StructType>(ShadowTy); + SmallVector<Constant *, 4> Vals; + for (unsigned i = 0, n = ST->getNumElements(); i < n; i++) + Vals.push_back(getPoisonedShadow(ST->getElementType(i))); + return ConstantStruct::get(ST, Vals); + } + + /// \brief Create a dirty shadow for a given value. + Constant *getPoisonedShadow(Value *V) { + Type *ShadowTy = getShadowTy(V); + if (!ShadowTy) + return 0; + return getPoisonedShadow(ShadowTy); + } + + /// \brief Create a clean (zero) origin. + Value *getCleanOrigin() { + return Constant::getNullValue(MS.OriginTy); + } + + /// \brief Get the shadow value for a given Value. + /// + /// This function either returns the value set earlier with setShadow, + /// or extracts if from ParamTLS (for function arguments). + Value *getShadow(Value *V) { + if (Instruction *I = dyn_cast<Instruction>(V)) { + // For instructions the shadow is already stored in the map. + Value *Shadow = ShadowMap[V]; + if (!Shadow) { + DEBUG(dbgs() << "No shadow: " << *V << "\n" << *(I->getParent())); + (void)I; + assert(Shadow && "No shadow for a value"); + } + return Shadow; + } + if (UndefValue *U = dyn_cast<UndefValue>(V)) { + Value *AllOnes = PoisonUndef ? getPoisonedShadow(V) : getCleanShadow(V); + DEBUG(dbgs() << "Undef: " << *U << " ==> " << *AllOnes << "\n"); + (void)U; + return AllOnes; + } + if (Argument *A = dyn_cast<Argument>(V)) { + // For arguments we compute the shadow on demand and store it in the map. + Value **ShadowPtr = &ShadowMap[V]; + if (*ShadowPtr) + return *ShadowPtr; + Function *F = A->getParent(); + IRBuilder<> EntryIRB(F->getEntryBlock().getFirstNonPHI()); + unsigned ArgOffset = 0; + for (Function::arg_iterator AI = F->arg_begin(), AE = F->arg_end(); + AI != AE; ++AI) { + if (!AI->getType()->isSized()) { + DEBUG(dbgs() << "Arg is not sized\n"); + continue; + } + unsigned Size = AI->hasByValAttr() + ? MS.TD->getTypeAllocSize(AI->getType()->getPointerElementType()) + : MS.TD->getTypeAllocSize(AI->getType()); + if (A == AI) { + Value *Base = getShadowPtrForArgument(AI, EntryIRB, ArgOffset); + if (AI->hasByValAttr()) { + // ByVal pointer itself has clean shadow. We copy the actual + // argument shadow to the underlying memory. + // Figure out maximal valid memcpy alignment. + unsigned ArgAlign = AI->getParamAlignment(); + if (ArgAlign == 0) { + Type *EltType = A->getType()->getPointerElementType(); + ArgAlign = MS.TD->getABITypeAlignment(EltType); + } + unsigned CopyAlign = std::min(ArgAlign, kShadowTLSAlignment); + Value *Cpy = EntryIRB.CreateMemCpy( + getShadowPtr(V, EntryIRB.getInt8Ty(), EntryIRB), Base, Size, + CopyAlign); + DEBUG(dbgs() << " ByValCpy: " << *Cpy << "\n"); + (void)Cpy; + *ShadowPtr = getCleanShadow(V); + } else { + *ShadowPtr = EntryIRB.CreateAlignedLoad(Base, kShadowTLSAlignment); + } + DEBUG(dbgs() << " ARG: " << *AI << " ==> " << + **ShadowPtr << "\n"); + if (MS.TrackOrigins) { + Value* OriginPtr = getOriginPtrForArgument(AI, EntryIRB, ArgOffset); + setOrigin(A, EntryIRB.CreateLoad(OriginPtr)); + } + } + ArgOffset += DataLayout::RoundUpAlignment(Size, kShadowTLSAlignment); + } + assert(*ShadowPtr && "Could not find shadow for an argument"); + return *ShadowPtr; + } + // For everything else the shadow is zero. + return getCleanShadow(V); + } + + /// \brief Get the shadow for i-th argument of the instruction I. + Value *getShadow(Instruction *I, int i) { + return getShadow(I->getOperand(i)); + } + + /// \brief Get the origin for a value. + Value *getOrigin(Value *V) { + if (!MS.TrackOrigins) return 0; + if (isa<Instruction>(V) || isa<Argument>(V)) { + Value *Origin = OriginMap[V]; + if (!Origin) { + DEBUG(dbgs() << "NO ORIGIN: " << *V << "\n"); + Origin = getCleanOrigin(); + } + return Origin; + } + return getCleanOrigin(); + } + + /// \brief Get the origin for i-th argument of the instruction I. + Value *getOrigin(Instruction *I, int i) { + return getOrigin(I->getOperand(i)); + } + + /// \brief Remember the place where a shadow check should be inserted. + /// + /// This location will be later instrumented with a check that will print a + /// UMR warning in runtime if the shadow value is not 0. + void insertShadowCheck(Value *Shadow, Value *Origin, Instruction *OrigIns) { + assert(Shadow); + if (!InsertChecks) return; +#ifndef NDEBUG + Type *ShadowTy = Shadow->getType(); + assert((isa<IntegerType>(ShadowTy) || isa<VectorType>(ShadowTy)) && + "Can only insert checks for integer and vector shadow types"); +#endif + InstrumentationList.push_back( + ShadowOriginAndInsertPoint(Shadow, Origin, OrigIns)); + } + + /// \brief Remember the place where a shadow check should be inserted. + /// + /// This location will be later instrumented with a check that will print a + /// UMR warning in runtime if the value is not fully defined. + void insertShadowCheck(Value *Val, Instruction *OrigIns) { + assert(Val); + Instruction *Shadow = dyn_cast_or_null<Instruction>(getShadow(Val)); + if (!Shadow) return; + Instruction *Origin = dyn_cast_or_null<Instruction>(getOrigin(Val)); + insertShadowCheck(Shadow, Origin, OrigIns); + } + + AtomicOrdering addReleaseOrdering(AtomicOrdering a) { + switch (a) { + case NotAtomic: + return NotAtomic; + case Unordered: + case Monotonic: + case Release: + return Release; + case Acquire: + case AcquireRelease: + return AcquireRelease; + case SequentiallyConsistent: + return SequentiallyConsistent; + } + llvm_unreachable("Unknown ordering"); + } + + AtomicOrdering addAcquireOrdering(AtomicOrdering a) { + switch (a) { + case NotAtomic: + return NotAtomic; + case Unordered: + case Monotonic: + case Acquire: + return Acquire; + case Release: + case AcquireRelease: + return AcquireRelease; + case SequentiallyConsistent: + return SequentiallyConsistent; + } + llvm_unreachable("Unknown ordering"); + } + + // ------------------- Visitors. + + /// \brief Instrument LoadInst + /// + /// Loads the corresponding shadow and (optionally) origin. + /// Optionally, checks that the load address is fully defined. + void visitLoadInst(LoadInst &I) { + assert(I.getType()->isSized() && "Load type must have size"); + IRBuilder<> IRB(I.getNextNode()); + Type *ShadowTy = getShadowTy(&I); + Value *Addr = I.getPointerOperand(); + if (LoadShadow) { + Value *ShadowPtr = getShadowPtr(Addr, ShadowTy, IRB); + setShadow(&I, + IRB.CreateAlignedLoad(ShadowPtr, I.getAlignment(), "_msld")); + } else { + setShadow(&I, getCleanShadow(&I)); + } + + if (ClCheckAccessAddress) + insertShadowCheck(I.getPointerOperand(), &I); + + if (I.isAtomic()) + I.setOrdering(addAcquireOrdering(I.getOrdering())); + + if (MS.TrackOrigins) { + if (LoadShadow) { + unsigned Alignment = std::max(kMinOriginAlignment, I.getAlignment()); + setOrigin(&I, + IRB.CreateAlignedLoad(getOriginPtr(Addr, IRB), Alignment)); + } else { + setOrigin(&I, getCleanOrigin()); + } + } + } + + /// \brief Instrument StoreInst + /// + /// Stores the corresponding shadow and (optionally) origin. + /// Optionally, checks that the store address is fully defined. + void visitStoreInst(StoreInst &I) { + StoreList.push_back(&I); + } + + void handleCASOrRMW(Instruction &I) { + assert(isa<AtomicRMWInst>(I) || isa<AtomicCmpXchgInst>(I)); + + IRBuilder<> IRB(&I); + Value *Addr = I.getOperand(0); + Value *ShadowPtr = getShadowPtr(Addr, I.getType(), IRB); + + if (ClCheckAccessAddress) + insertShadowCheck(Addr, &I); + + // Only test the conditional argument of cmpxchg instruction. + // The other argument can potentially be uninitialized, but we can not + // detect this situation reliably without possible false positives. + if (isa<AtomicCmpXchgInst>(I)) + insertShadowCheck(I.getOperand(1), &I); + + IRB.CreateStore(getCleanShadow(&I), ShadowPtr); + + setShadow(&I, getCleanShadow(&I)); + } + + void visitAtomicRMWInst(AtomicRMWInst &I) { + handleCASOrRMW(I); + I.setOrdering(addReleaseOrdering(I.getOrdering())); + } + + void visitAtomicCmpXchgInst(AtomicCmpXchgInst &I) { + handleCASOrRMW(I); + I.setOrdering(addReleaseOrdering(I.getOrdering())); + } + + // Vector manipulation. + void visitExtractElementInst(ExtractElementInst &I) { + insertShadowCheck(I.getOperand(1), &I); + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateExtractElement(getShadow(&I, 0), I.getOperand(1), + "_msprop")); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitInsertElementInst(InsertElementInst &I) { + insertShadowCheck(I.getOperand(2), &I); + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateInsertElement(getShadow(&I, 0), getShadow(&I, 1), + I.getOperand(2), "_msprop")); + setOriginForNaryOp(I); + } + + void visitShuffleVectorInst(ShuffleVectorInst &I) { + insertShadowCheck(I.getOperand(2), &I); + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateShuffleVector(getShadow(&I, 0), getShadow(&I, 1), + I.getOperand(2), "_msprop")); + setOriginForNaryOp(I); + } + + // Casts. + void visitSExtInst(SExtInst &I) { + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateSExt(getShadow(&I, 0), I.getType(), "_msprop")); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitZExtInst(ZExtInst &I) { + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateZExt(getShadow(&I, 0), I.getType(), "_msprop")); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitTruncInst(TruncInst &I) { + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateTrunc(getShadow(&I, 0), I.getType(), "_msprop")); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitBitCastInst(BitCastInst &I) { + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateBitCast(getShadow(&I, 0), getShadowTy(&I))); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitPtrToIntInst(PtrToIntInst &I) { + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateIntCast(getShadow(&I, 0), getShadowTy(&I), false, + "_msprop_ptrtoint")); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitIntToPtrInst(IntToPtrInst &I) { + IRBuilder<> IRB(&I); + setShadow(&I, IRB.CreateIntCast(getShadow(&I, 0), getShadowTy(&I), false, + "_msprop_inttoptr")); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitFPToSIInst(CastInst& I) { handleShadowOr(I); } + void visitFPToUIInst(CastInst& I) { handleShadowOr(I); } + void visitSIToFPInst(CastInst& I) { handleShadowOr(I); } + void visitUIToFPInst(CastInst& I) { handleShadowOr(I); } + void visitFPExtInst(CastInst& I) { handleShadowOr(I); } + void visitFPTruncInst(CastInst& I) { handleShadowOr(I); } + + /// \brief Propagate shadow for bitwise AND. + /// + /// This code is exact, i.e. if, for example, a bit in the left argument + /// is defined and 0, then neither the value not definedness of the + /// corresponding bit in B don't affect the resulting shadow. + void visitAnd(BinaryOperator &I) { + IRBuilder<> IRB(&I); + // "And" of 0 and a poisoned value results in unpoisoned value. + // 1&1 => 1; 0&1 => 0; p&1 => p; + // 1&0 => 0; 0&0 => 0; p&0 => 0; + // 1&p => p; 0&p => 0; p&p => p; + // S = (S1 & S2) | (V1 & S2) | (S1 & V2) + Value *S1 = getShadow(&I, 0); + Value *S2 = getShadow(&I, 1); + Value *V1 = I.getOperand(0); + Value *V2 = I.getOperand(1); + if (V1->getType() != S1->getType()) { + V1 = IRB.CreateIntCast(V1, S1->getType(), false); + V2 = IRB.CreateIntCast(V2, S2->getType(), false); + } + Value *S1S2 = IRB.CreateAnd(S1, S2); + Value *V1S2 = IRB.CreateAnd(V1, S2); + Value *S1V2 = IRB.CreateAnd(S1, V2); + setShadow(&I, IRB.CreateOr(S1S2, IRB.CreateOr(V1S2, S1V2))); + setOriginForNaryOp(I); + } + + void visitOr(BinaryOperator &I) { + IRBuilder<> IRB(&I); + // "Or" of 1 and a poisoned value results in unpoisoned value. + // 1|1 => 1; 0|1 => 1; p|1 => 1; + // 1|0 => 1; 0|0 => 0; p|0 => p; + // 1|p => 1; 0|p => p; p|p => p; + // S = (S1 & S2) | (~V1 & S2) | (S1 & ~V2) + Value *S1 = getShadow(&I, 0); + Value *S2 = getShadow(&I, 1); + Value *V1 = IRB.CreateNot(I.getOperand(0)); + Value *V2 = IRB.CreateNot(I.getOperand(1)); + if (V1->getType() != S1->getType()) { + V1 = IRB.CreateIntCast(V1, S1->getType(), false); + V2 = IRB.CreateIntCast(V2, S2->getType(), false); + } + Value *S1S2 = IRB.CreateAnd(S1, S2); + Value *V1S2 = IRB.CreateAnd(V1, S2); + Value *S1V2 = IRB.CreateAnd(S1, V2); + setShadow(&I, IRB.CreateOr(S1S2, IRB.CreateOr(V1S2, S1V2))); + setOriginForNaryOp(I); + } + + /// \brief Default propagation of shadow and/or origin. + /// + /// This class implements the general case of shadow propagation, used in all + /// cases where we don't know and/or don't care about what the operation + /// actually does. It converts all input shadow values to a common type + /// (extending or truncating as necessary), and bitwise OR's them. + /// + /// This is much cheaper than inserting checks (i.e. requiring inputs to be + /// fully initialized), and less prone to false positives. + /// + /// This class also implements the general case of origin propagation. For a + /// Nary operation, result origin is set to the origin of an argument that is + /// not entirely initialized. If there is more than one such arguments, the + /// rightmost of them is picked. It does not matter which one is picked if all + /// arguments are initialized. + template <bool CombineShadow> + class Combiner { + Value *Shadow; + Value *Origin; + IRBuilder<> &IRB; + MemorySanitizerVisitor *MSV; + + public: + Combiner(MemorySanitizerVisitor *MSV, IRBuilder<> &IRB) : + Shadow(0), Origin(0), IRB(IRB), MSV(MSV) {} + + /// \brief Add a pair of shadow and origin values to the mix. + Combiner &Add(Value *OpShadow, Value *OpOrigin) { + if (CombineShadow) { + assert(OpShadow); + if (!Shadow) + Shadow = OpShadow; + else { + OpShadow = MSV->CreateShadowCast(IRB, OpShadow, Shadow->getType()); + Shadow = IRB.CreateOr(Shadow, OpShadow, "_msprop"); + } + } + + if (MSV->MS.TrackOrigins) { + assert(OpOrigin); + if (!Origin) { + Origin = OpOrigin; + } else { + Value *FlatShadow = MSV->convertToShadowTyNoVec(OpShadow, IRB); + Value *Cond = IRB.CreateICmpNE(FlatShadow, + MSV->getCleanShadow(FlatShadow)); + Origin = IRB.CreateSelect(Cond, OpOrigin, Origin); + } + } + return *this; + } + + /// \brief Add an application value to the mix. + Combiner &Add(Value *V) { + Value *OpShadow = MSV->getShadow(V); + Value *OpOrigin = MSV->MS.TrackOrigins ? MSV->getOrigin(V) : 0; + return Add(OpShadow, OpOrigin); + } + + /// \brief Set the current combined values as the given instruction's shadow + /// and origin. + void Done(Instruction *I) { + if (CombineShadow) { + assert(Shadow); + Shadow = MSV->CreateShadowCast(IRB, Shadow, MSV->getShadowTy(I)); + MSV->setShadow(I, Shadow); + } + if (MSV->MS.TrackOrigins) { + assert(Origin); + MSV->setOrigin(I, Origin); + } + } + }; + + typedef Combiner<true> ShadowAndOriginCombiner; + typedef Combiner<false> OriginCombiner; + + /// \brief Propagate origin for arbitrary operation. + void setOriginForNaryOp(Instruction &I) { + if (!MS.TrackOrigins) return; + IRBuilder<> IRB(&I); + OriginCombiner OC(this, IRB); + for (Instruction::op_iterator OI = I.op_begin(); OI != I.op_end(); ++OI) + OC.Add(OI->get()); + OC.Done(&I); + } + + size_t VectorOrPrimitiveTypeSizeInBits(Type *Ty) { + assert(!(Ty->isVectorTy() && Ty->getScalarType()->isPointerTy()) && + "Vector of pointers is not a valid shadow type"); + return Ty->isVectorTy() ? + Ty->getVectorNumElements() * Ty->getScalarSizeInBits() : + Ty->getPrimitiveSizeInBits(); + } + + /// \brief Cast between two shadow types, extending or truncating as + /// necessary. + Value *CreateShadowCast(IRBuilder<> &IRB, Value *V, Type *dstTy, + bool Signed = false) { + Type *srcTy = V->getType(); + if (dstTy->isIntegerTy() && srcTy->isIntegerTy()) + return IRB.CreateIntCast(V, dstTy, Signed); + if (dstTy->isVectorTy() && srcTy->isVectorTy() && + dstTy->getVectorNumElements() == srcTy->getVectorNumElements()) + return IRB.CreateIntCast(V, dstTy, Signed); + size_t srcSizeInBits = VectorOrPrimitiveTypeSizeInBits(srcTy); + size_t dstSizeInBits = VectorOrPrimitiveTypeSizeInBits(dstTy); + Value *V1 = IRB.CreateBitCast(V, Type::getIntNTy(*MS.C, srcSizeInBits)); + Value *V2 = + IRB.CreateIntCast(V1, Type::getIntNTy(*MS.C, dstSizeInBits), Signed); + return IRB.CreateBitCast(V2, dstTy); + // TODO: handle struct types. + } + + /// \brief Propagate shadow for arbitrary operation. + void handleShadowOr(Instruction &I) { + IRBuilder<> IRB(&I); + ShadowAndOriginCombiner SC(this, IRB); + for (Instruction::op_iterator OI = I.op_begin(); OI != I.op_end(); ++OI) + SC.Add(OI->get()); + SC.Done(&I); + } + + void visitFAdd(BinaryOperator &I) { handleShadowOr(I); } + void visitFSub(BinaryOperator &I) { handleShadowOr(I); } + void visitFMul(BinaryOperator &I) { handleShadowOr(I); } + void visitAdd(BinaryOperator &I) { handleShadowOr(I); } + void visitSub(BinaryOperator &I) { handleShadowOr(I); } + void visitXor(BinaryOperator &I) { handleShadowOr(I); } + void visitMul(BinaryOperator &I) { handleShadowOr(I); } + + void handleDiv(Instruction &I) { + IRBuilder<> IRB(&I); + // Strict on the second argument. + insertShadowCheck(I.getOperand(1), &I); + setShadow(&I, getShadow(&I, 0)); + setOrigin(&I, getOrigin(&I, 0)); + } + + void visitUDiv(BinaryOperator &I) { handleDiv(I); } + void visitSDiv(BinaryOperator &I) { handleDiv(I); } + void visitFDiv(BinaryOperator &I) { handleDiv(I); } + void visitURem(BinaryOperator &I) { handleDiv(I); } + void visitSRem(BinaryOperator &I) { handleDiv(I); } + void visitFRem(BinaryOperator &I) { handleDiv(I); } + + /// \brief Instrument == and != comparisons. + /// + /// Sometimes the comparison result is known even if some of the bits of the + /// arguments are not. + void handleEqualityComparison(ICmpInst &I) { + IRBuilder<> IRB(&I); + Value *A = I.getOperand(0); + Value *B = I.getOperand(1); + Value *Sa = getShadow(A); + Value *Sb = getShadow(B); + + // Get rid of pointers and vectors of pointers. + // For ints (and vectors of ints), types of A and Sa match, + // and this is a no-op. + A = IRB.CreatePointerCast(A, Sa->getType()); + B = IRB.CreatePointerCast(B, Sb->getType()); + + // A == B <==> (C = A^B) == 0 + // A != B <==> (C = A^B) != 0 + // Sc = Sa | Sb + Value *C = IRB.CreateXor(A, B); + Value *Sc = IRB.CreateOr(Sa, Sb); + // Now dealing with i = (C == 0) comparison (or C != 0, does not matter now) + // Result is defined if one of the following is true + // * there is a defined 1 bit in C + // * C is fully defined + // Si = !(C & ~Sc) && Sc + Value *Zero = Constant::getNullValue(Sc->getType()); + Value *MinusOne = Constant::getAllOnesValue(Sc->getType()); + Value *Si = + IRB.CreateAnd(IRB.CreateICmpNE(Sc, Zero), + IRB.CreateICmpEQ( + IRB.CreateAnd(IRB.CreateXor(Sc, MinusOne), C), Zero)); + Si->setName("_msprop_icmp"); + setShadow(&I, Si); + setOriginForNaryOp(I); + } + + /// \brief Build the lowest possible value of V, taking into account V's + /// uninitialized bits. + Value *getLowestPossibleValue(IRBuilder<> &IRB, Value *A, Value *Sa, + bool isSigned) { + if (isSigned) { + // Split shadow into sign bit and other bits. + Value *SaOtherBits = IRB.CreateLShr(IRB.CreateShl(Sa, 1), 1); + Value *SaSignBit = IRB.CreateXor(Sa, SaOtherBits); + // Maximise the undefined shadow bit, minimize other undefined bits. + return + IRB.CreateOr(IRB.CreateAnd(A, IRB.CreateNot(SaOtherBits)), SaSignBit); + } else { + // Minimize undefined bits. + return IRB.CreateAnd(A, IRB.CreateNot(Sa)); + } + } + + /// \brief Build the highest possible value of V, taking into account V's + /// uninitialized bits. + Value *getHighestPossibleValue(IRBuilder<> &IRB, Value *A, Value *Sa, + bool isSigned) { + if (isSigned) { + // Split shadow into sign bit and other bits. + Value *SaOtherBits = IRB.CreateLShr(IRB.CreateShl(Sa, 1), 1); + Value *SaSignBit = IRB.CreateXor(Sa, SaOtherBits); + // Minimise the undefined shadow bit, maximise other undefined bits. + return + IRB.CreateOr(IRB.CreateAnd(A, IRB.CreateNot(SaSignBit)), SaOtherBits); + } else { + // Maximize undefined bits. + return IRB.CreateOr(A, Sa); + } + } + + /// \brief Instrument relational comparisons. + /// + /// This function does exact shadow propagation for all relational + /// comparisons of integers, pointers and vectors of those. + /// FIXME: output seems suboptimal when one of the operands is a constant + void handleRelationalComparisonExact(ICmpInst &I) { + IRBuilder<> IRB(&I); + Value *A = I.getOperand(0); + Value *B = I.getOperand(1); + Value *Sa = getShadow(A); + Value *Sb = getShadow(B); + + // Get rid of pointers and vectors of pointers. + // For ints (and vectors of ints), types of A and Sa match, + // and this is a no-op. + A = IRB.CreatePointerCast(A, Sa->getType()); + B = IRB.CreatePointerCast(B, Sb->getType()); + + // Let [a0, a1] be the interval of possible values of A, taking into account + // its undefined bits. Let [b0, b1] be the interval of possible values of B. + // Then (A cmp B) is defined iff (a0 cmp b1) == (a1 cmp b0). + bool IsSigned = I.isSigned(); + Value *S1 = IRB.CreateICmp(I.getPredicate(), + getLowestPossibleValue(IRB, A, Sa, IsSigned), + getHighestPossibleValue(IRB, B, Sb, IsSigned)); + Value *S2 = IRB.CreateICmp(I.getPredicate(), + getHighestPossibleValue(IRB, A, Sa, IsSigned), + getLowestPossibleValue(IRB, B, Sb, IsSigned)); + Value *Si = IRB.CreateXor(S1, S2); + setShadow(&I, Si); + setOriginForNaryOp(I); + } + + /// \brief Instrument signed relational comparisons. + /// + /// Handle (x<0) and (x>=0) comparisons (essentially, sign bit tests) by + /// propagating the highest bit of the shadow. Everything else is delegated + /// to handleShadowOr(). + void handleSignedRelationalComparison(ICmpInst &I) { + Constant *constOp0 = dyn_cast<Constant>(I.getOperand(0)); + Constant *constOp1 = dyn_cast<Constant>(I.getOperand(1)); + Value* op = NULL; + CmpInst::Predicate pre = I.getPredicate(); + if (constOp0 && constOp0->isNullValue() && + (pre == CmpInst::ICMP_SGT || pre == CmpInst::ICMP_SLE)) { + op = I.getOperand(1); + } else if (constOp1 && constOp1->isNullValue() && + (pre == CmpInst::ICMP_SLT || pre == CmpInst::ICMP_SGE)) { + op = I.getOperand(0); + } + if (op) { + IRBuilder<> IRB(&I); + Value* Shadow = + IRB.CreateICmpSLT(getShadow(op), getCleanShadow(op), "_msprop_icmpslt"); + setShadow(&I, Shadow); + setOrigin(&I, getOrigin(op)); + } else { + handleShadowOr(I); + } + } + + void visitICmpInst(ICmpInst &I) { + if (!ClHandleICmp) { + handleShadowOr(I); + return; + } + if (I.isEquality()) { + handleEqualityComparison(I); + return; + } + + assert(I.isRelational()); + if (ClHandleICmpExact) { + handleRelationalComparisonExact(I); + return; + } + if (I.isSigned()) { + handleSignedRelationalComparison(I); + return; + } + + assert(I.isUnsigned()); + if ((isa<Constant>(I.getOperand(0)) || isa<Constant>(I.getOperand(1)))) { + handleRelationalComparisonExact(I); + return; + } + + handleShadowOr(I); + } + + void visitFCmpInst(FCmpInst &I) { + handleShadowOr(I); + } + + void handleShift(BinaryOperator &I) { + IRBuilder<> IRB(&I); + // If any of the S2 bits are poisoned, the whole thing is poisoned. + // Otherwise perform the same shift on S1. + Value *S1 = getShadow(&I, 0); + Value *S2 = getShadow(&I, 1); + Value *S2Conv = IRB.CreateSExt(IRB.CreateICmpNE(S2, getCleanShadow(S2)), + S2->getType()); + Value *V2 = I.getOperand(1); + Value *Shift = IRB.CreateBinOp(I.getOpcode(), S1, V2); + setShadow(&I, IRB.CreateOr(Shift, S2Conv)); + setOriginForNaryOp(I); + } + + void visitShl(BinaryOperator &I) { handleShift(I); } + void visitAShr(BinaryOperator &I) { handleShift(I); } + void visitLShr(BinaryOperator &I) { handleShift(I); } + + /// \brief Instrument llvm.memmove + /// + /// At this point we don't know if llvm.memmove will be inlined or not. + /// If we don't instrument it and it gets inlined, + /// our interceptor will not kick in and we will lose the memmove. + /// If we instrument the call here, but it does not get inlined, + /// we will memove the shadow twice: which is bad in case + /// of overlapping regions. So, we simply lower the intrinsic to a call. + /// + /// Similar situation exists for memcpy and memset. + void visitMemMoveInst(MemMoveInst &I) { + IRBuilder<> IRB(&I); + IRB.CreateCall3( + MS.MemmoveFn, + IRB.CreatePointerCast(I.getArgOperand(0), IRB.getInt8PtrTy()), + IRB.CreatePointerCast(I.getArgOperand(1), IRB.getInt8PtrTy()), + IRB.CreateIntCast(I.getArgOperand(2), MS.IntptrTy, false)); + I.eraseFromParent(); + } + + // Similar to memmove: avoid copying shadow twice. + // This is somewhat unfortunate as it may slowdown small constant memcpys. + // FIXME: consider doing manual inline for small constant sizes and proper + // alignment. + void visitMemCpyInst(MemCpyInst &I) { + IRBuilder<> IRB(&I); + IRB.CreateCall3( + MS.MemcpyFn, + IRB.CreatePointerCast(I.getArgOperand(0), IRB.getInt8PtrTy()), + IRB.CreatePointerCast(I.getArgOperand(1), IRB.getInt8PtrTy()), + IRB.CreateIntCast(I.getArgOperand(2), MS.IntptrTy, false)); + I.eraseFromParent(); + } + + // Same as memcpy. + void visitMemSetInst(MemSetInst &I) { + IRBuilder<> IRB(&I); + IRB.CreateCall3( + MS.MemsetFn, + IRB.CreatePointerCast(I.getArgOperand(0), IRB.getInt8PtrTy()), + IRB.CreateIntCast(I.getArgOperand(1), IRB.getInt32Ty(), false), + IRB.CreateIntCast(I.getArgOperand(2), MS.IntptrTy, false)); + I.eraseFromParent(); + } + + void visitVAStartInst(VAStartInst &I) { + VAHelper->visitVAStartInst(I); + } + + void visitVACopyInst(VACopyInst &I) { + VAHelper->visitVACopyInst(I); + } + + enum IntrinsicKind { + IK_DoesNotAccessMemory, + IK_OnlyReadsMemory, + IK_WritesMemory + }; + + static IntrinsicKind getIntrinsicKind(Intrinsic::ID iid) { + const int DoesNotAccessMemory = IK_DoesNotAccessMemory; + const int OnlyReadsArgumentPointees = IK_OnlyReadsMemory; + const int OnlyReadsMemory = IK_OnlyReadsMemory; + const int OnlyAccessesArgumentPointees = IK_WritesMemory; + const int UnknownModRefBehavior = IK_WritesMemory; +#define GET_INTRINSIC_MODREF_BEHAVIOR +#define ModRefBehavior IntrinsicKind +#include "llvm/IR/Intrinsics.gen" +#undef ModRefBehavior +#undef GET_INTRINSIC_MODREF_BEHAVIOR + } + + /// \brief Handle vector store-like intrinsics. + /// + /// Instrument intrinsics that look like a simple SIMD store: writes memory, + /// has 1 pointer argument and 1 vector argument, returns void. + bool handleVectorStoreIntrinsic(IntrinsicInst &I) { + IRBuilder<> IRB(&I); + Value* Addr = I.getArgOperand(0); + Value *Shadow = getShadow(&I, 1); + Value *ShadowPtr = getShadowPtr(Addr, Shadow->getType(), IRB); + + // We don't know the pointer alignment (could be unaligned SSE store!). + // Have to assume to worst case. + IRB.CreateAlignedStore(Shadow, ShadowPtr, 1); + + if (ClCheckAccessAddress) + insertShadowCheck(Addr, &I); + + // FIXME: use ClStoreCleanOrigin + // FIXME: factor out common code from materializeStores + if (MS.TrackOrigins) + IRB.CreateStore(getOrigin(&I, 1), getOriginPtr(Addr, IRB)); + return true; + } + + /// \brief Handle vector load-like intrinsics. + /// + /// Instrument intrinsics that look like a simple SIMD load: reads memory, + /// has 1 pointer argument, returns a vector. + bool handleVectorLoadIntrinsic(IntrinsicInst &I) { + IRBuilder<> IRB(&I); + Value *Addr = I.getArgOperand(0); + + Type *ShadowTy = getShadowTy(&I); + if (LoadShadow) { + Value *ShadowPtr = getShadowPtr(Addr, ShadowTy, IRB); + // We don't know the pointer alignment (could be unaligned SSE load!). + // Have to assume to worst case. + setShadow(&I, IRB.CreateAlignedLoad(ShadowPtr, 1, "_msld")); + } else { + setShadow(&I, getCleanShadow(&I)); + } + + if (ClCheckAccessAddress) + insertShadowCheck(Addr, &I); + + if (MS.TrackOrigins) { + if (LoadShadow) + setOrigin(&I, IRB.CreateLoad(getOriginPtr(Addr, IRB))); + else + setOrigin(&I, getCleanOrigin()); + } + return true; + } + + /// \brief Handle (SIMD arithmetic)-like intrinsics. + /// + /// Instrument intrinsics with any number of arguments of the same type, + /// equal to the return type. The type should be simple (no aggregates or + /// pointers; vectors are fine). + /// Caller guarantees that this intrinsic does not access memory. + bool maybeHandleSimpleNomemIntrinsic(IntrinsicInst &I) { + Type *RetTy = I.getType(); + if (!(RetTy->isIntOrIntVectorTy() || + RetTy->isFPOrFPVectorTy() || + RetTy->isX86_MMXTy())) + return false; + + unsigned NumArgOperands = I.getNumArgOperands(); + + for (unsigned i = 0; i < NumArgOperands; ++i) { + Type *Ty = I.getArgOperand(i)->getType(); + if (Ty != RetTy) + return false; + } + + IRBuilder<> IRB(&I); + ShadowAndOriginCombiner SC(this, IRB); + for (unsigned i = 0; i < NumArgOperands; ++i) + SC.Add(I.getArgOperand(i)); + SC.Done(&I); + + return true; + } + + /// \brief Heuristically instrument unknown intrinsics. + /// + /// The main purpose of this code is to do something reasonable with all + /// random intrinsics we might encounter, most importantly - SIMD intrinsics. + /// We recognize several classes of intrinsics by their argument types and + /// ModRefBehaviour and apply special intrumentation when we are reasonably + /// sure that we know what the intrinsic does. + /// + /// We special-case intrinsics where this approach fails. See llvm.bswap + /// handling as an example of that. + bool handleUnknownIntrinsic(IntrinsicInst &I) { + unsigned NumArgOperands = I.getNumArgOperands(); + if (NumArgOperands == 0) + return false; + + Intrinsic::ID iid = I.getIntrinsicID(); + IntrinsicKind IK = getIntrinsicKind(iid); + bool OnlyReadsMemory = IK == IK_OnlyReadsMemory; + bool WritesMemory = IK == IK_WritesMemory; + assert(!(OnlyReadsMemory && WritesMemory)); + + if (NumArgOperands == 2 && + I.getArgOperand(0)->getType()->isPointerTy() && + I.getArgOperand(1)->getType()->isVectorTy() && + I.getType()->isVoidTy() && + WritesMemory) { + // This looks like a vector store. + return handleVectorStoreIntrinsic(I); + } + + if (NumArgOperands == 1 && + I.getArgOperand(0)->getType()->isPointerTy() && + I.getType()->isVectorTy() && + OnlyReadsMemory) { + // This looks like a vector load. + return handleVectorLoadIntrinsic(I); + } + + if (!OnlyReadsMemory && !WritesMemory) + if (maybeHandleSimpleNomemIntrinsic(I)) + return true; + + // FIXME: detect and handle SSE maskstore/maskload + return false; + } + + void handleBswap(IntrinsicInst &I) { + IRBuilder<> IRB(&I); + Value *Op = I.getArgOperand(0); + Type *OpType = Op->getType(); + Function *BswapFunc = Intrinsic::getDeclaration( + F.getParent(), Intrinsic::bswap, ArrayRef<Type*>(&OpType, 1)); + setShadow(&I, IRB.CreateCall(BswapFunc, getShadow(Op))); + setOrigin(&I, getOrigin(Op)); + } + + // \brief Instrument vector convert instrinsic. + // + // This function instruments intrinsics like cvtsi2ss: + // %Out = int_xxx_cvtyyy(%ConvertOp) + // or + // %Out = int_xxx_cvtyyy(%CopyOp, %ConvertOp) + // Intrinsic converts \p NumUsedElements elements of \p ConvertOp to the same + // number \p Out elements, and (if has 2 arguments) copies the rest of the + // elements from \p CopyOp. + // In most cases conversion involves floating-point value which may trigger a + // hardware exception when not fully initialized. For this reason we require + // \p ConvertOp[0:NumUsedElements] to be fully initialized and trap otherwise. + // We copy the shadow of \p CopyOp[NumUsedElements:] to \p + // Out[NumUsedElements:]. This means that intrinsics without \p CopyOp always + // return a fully initialized value. + void handleVectorConvertIntrinsic(IntrinsicInst &I, int NumUsedElements) { + IRBuilder<> IRB(&I); + Value *CopyOp, *ConvertOp; + + switch (I.getNumArgOperands()) { + case 2: + CopyOp = I.getArgOperand(0); + ConvertOp = I.getArgOperand(1); + break; + case 1: + ConvertOp = I.getArgOperand(0); + CopyOp = NULL; + break; + default: + llvm_unreachable("Cvt intrinsic with unsupported number of arguments."); + } + + // The first *NumUsedElements* elements of ConvertOp are converted to the + // same number of output elements. The rest of the output is copied from + // CopyOp, or (if not available) filled with zeroes. + // Combine shadow for elements of ConvertOp that are used in this operation, + // and insert a check. + // FIXME: consider propagating shadow of ConvertOp, at least in the case of + // int->any conversion. + Value *ConvertShadow = getShadow(ConvertOp); + Value *AggShadow = 0; + if (ConvertOp->getType()->isVectorTy()) { + AggShadow = IRB.CreateExtractElement( + ConvertShadow, ConstantInt::get(IRB.getInt32Ty(), 0)); + for (int i = 1; i < NumUsedElements; ++i) { + Value *MoreShadow = IRB.CreateExtractElement( + ConvertShadow, ConstantInt::get(IRB.getInt32Ty(), i)); + AggShadow = IRB.CreateOr(AggShadow, MoreShadow); + } + } else { + AggShadow = ConvertShadow; + } + assert(AggShadow->getType()->isIntegerTy()); + insertShadowCheck(AggShadow, getOrigin(ConvertOp), &I); + + // Build result shadow by zero-filling parts of CopyOp shadow that come from + // ConvertOp. + if (CopyOp) { + assert(CopyOp->getType() == I.getType()); + assert(CopyOp->getType()->isVectorTy()); + Value *ResultShadow = getShadow(CopyOp); + Type *EltTy = ResultShadow->getType()->getVectorElementType(); + for (int i = 0; i < NumUsedElements; ++i) { + ResultShadow = IRB.CreateInsertElement( + ResultShadow, ConstantInt::getNullValue(EltTy), + ConstantInt::get(IRB.getInt32Ty(), i)); + } + setShadow(&I, ResultShadow); + setOrigin(&I, getOrigin(CopyOp)); + } else { + setShadow(&I, getCleanShadow(&I)); + } + } + + void visitIntrinsicInst(IntrinsicInst &I) { + switch (I.getIntrinsicID()) { + case llvm::Intrinsic::bswap: + handleBswap(I); + break; + case llvm::Intrinsic::x86_avx512_cvtsd2usi64: + case llvm::Intrinsic::x86_avx512_cvtsd2usi: + case llvm::Intrinsic::x86_avx512_cvtss2usi64: + case llvm::Intrinsic::x86_avx512_cvtss2usi: + case llvm::Intrinsic::x86_avx512_cvttss2usi64: + case llvm::Intrinsic::x86_avx512_cvttss2usi: + case llvm::Intrinsic::x86_avx512_cvttsd2usi64: + case llvm::Intrinsic::x86_avx512_cvttsd2usi: + case llvm::Intrinsic::x86_avx512_cvtusi2sd: + case llvm::Intrinsic::x86_avx512_cvtusi2ss: + case llvm::Intrinsic::x86_avx512_cvtusi642sd: + case llvm::Intrinsic::x86_avx512_cvtusi642ss: + case llvm::Intrinsic::x86_sse2_cvtsd2si64: + case llvm::Intrinsic::x86_sse2_cvtsd2si: + case llvm::Intrinsic::x86_sse2_cvtsd2ss: + case llvm::Intrinsic::x86_sse2_cvtsi2sd: + case llvm::Intrinsic::x86_sse2_cvtsi642sd: + case llvm::Intrinsic::x86_sse2_cvtss2sd: + case llvm::Intrinsic::x86_sse2_cvttsd2si64: + case llvm::Intrinsic::x86_sse2_cvttsd2si: + case llvm::Intrinsic::x86_sse_cvtsi2ss: + case llvm::Intrinsic::x86_sse_cvtsi642ss: + case llvm::Intrinsic::x86_sse_cvtss2si64: + case llvm::Intrinsic::x86_sse_cvtss2si: + case llvm::Intrinsic::x86_sse_cvttss2si64: + case llvm::Intrinsic::x86_sse_cvttss2si: + handleVectorConvertIntrinsic(I, 1); + break; + case llvm::Intrinsic::x86_sse2_cvtdq2pd: + case llvm::Intrinsic::x86_sse2_cvtps2pd: + case llvm::Intrinsic::x86_sse_cvtps2pi: + case llvm::Intrinsic::x86_sse_cvttps2pi: + handleVectorConvertIntrinsic(I, 2); + break; + default: + if (!handleUnknownIntrinsic(I)) + visitInstruction(I); + break; + } + } + + void visitCallSite(CallSite CS) { + Instruction &I = *CS.getInstruction(); + assert((CS.isCall() || CS.isInvoke()) && "Unknown type of CallSite"); + if (CS.isCall()) { + CallInst *Call = cast<CallInst>(&I); + + // For inline asm, do the usual thing: check argument shadow and mark all + // outputs as clean. Note that any side effects of the inline asm that are + // not immediately visible in its constraints are not handled. + if (Call->isInlineAsm()) { + visitInstruction(I); + return; + } + + // Allow only tail calls with the same types, otherwise + // we may have a false positive: shadow for a non-void RetVal + // will get propagated to a void RetVal. + if (Call->isTailCall() && Call->getType() != Call->getParent()->getType()) + Call->setTailCall(false); + + assert(!isa<IntrinsicInst>(&I) && "intrinsics are handled elsewhere"); + + // We are going to insert code that relies on the fact that the callee + // will become a non-readonly function after it is instrumented by us. To + // prevent this code from being optimized out, mark that function + // non-readonly in advance. + if (Function *Func = Call->getCalledFunction()) { + // Clear out readonly/readnone attributes. + AttrBuilder B; + B.addAttribute(Attribute::ReadOnly) + .addAttribute(Attribute::ReadNone); + Func->removeAttributes(AttributeSet::FunctionIndex, + AttributeSet::get(Func->getContext(), + AttributeSet::FunctionIndex, + B)); + } + } + IRBuilder<> IRB(&I); + + if (MS.WrapIndirectCalls && !CS.getCalledFunction()) + IndirectCallList.push_back(CS); + + unsigned ArgOffset = 0; + DEBUG(dbgs() << " CallSite: " << I << "\n"); + for (CallSite::arg_iterator ArgIt = CS.arg_begin(), End = CS.arg_end(); + ArgIt != End; ++ArgIt) { + Value *A = *ArgIt; + unsigned i = ArgIt - CS.arg_begin(); + if (!A->getType()->isSized()) { + DEBUG(dbgs() << "Arg " << i << " is not sized: " << I << "\n"); + continue; + } + unsigned Size = 0; + Value *Store = 0; + // Compute the Shadow for arg even if it is ByVal, because + // in that case getShadow() will copy the actual arg shadow to + // __msan_param_tls. + Value *ArgShadow = getShadow(A); + Value *ArgShadowBase = getShadowPtrForArgument(A, IRB, ArgOffset); + DEBUG(dbgs() << " Arg#" << i << ": " << *A << + " Shadow: " << *ArgShadow << "\n"); + if (CS.paramHasAttr(i + 1, Attribute::ByVal)) { + assert(A->getType()->isPointerTy() && + "ByVal argument is not a pointer!"); + Size = MS.TD->getTypeAllocSize(A->getType()->getPointerElementType()); + unsigned Alignment = CS.getParamAlignment(i + 1); + Store = IRB.CreateMemCpy(ArgShadowBase, + getShadowPtr(A, Type::getInt8Ty(*MS.C), IRB), + Size, Alignment); + } else { + Size = MS.TD->getTypeAllocSize(A->getType()); + Store = IRB.CreateAlignedStore(ArgShadow, ArgShadowBase, + kShadowTLSAlignment); + } + if (MS.TrackOrigins) + IRB.CreateStore(getOrigin(A), + getOriginPtrForArgument(A, IRB, ArgOffset)); + (void)Store; + assert(Size != 0 && Store != 0); + DEBUG(dbgs() << " Param:" << *Store << "\n"); + ArgOffset += DataLayout::RoundUpAlignment(Size, 8); + } + DEBUG(dbgs() << " done with call args\n"); + + FunctionType *FT = + cast<FunctionType>(CS.getCalledValue()->getType()->getContainedType(0)); + if (FT->isVarArg()) { + VAHelper->visitCallSite(CS, IRB); + } + + // Now, get the shadow for the RetVal. + if (!I.getType()->isSized()) return; + IRBuilder<> IRBBefore(&I); + // Untill we have full dynamic coverage, make sure the retval shadow is 0. + Value *Base = getShadowPtrForRetval(&I, IRBBefore); + IRBBefore.CreateAlignedStore(getCleanShadow(&I), Base, kShadowTLSAlignment); + Instruction *NextInsn = 0; + if (CS.isCall()) { + NextInsn = I.getNextNode(); + } else { + BasicBlock *NormalDest = cast<InvokeInst>(&I)->getNormalDest(); + if (!NormalDest->getSinglePredecessor()) { + // FIXME: this case is tricky, so we are just conservative here. + // Perhaps we need to split the edge between this BB and NormalDest, + // but a naive attempt to use SplitEdge leads to a crash. + setShadow(&I, getCleanShadow(&I)); + setOrigin(&I, getCleanOrigin()); + return; + } + NextInsn = NormalDest->getFirstInsertionPt(); + assert(NextInsn && + "Could not find insertion point for retval shadow load"); + } + IRBuilder<> IRBAfter(NextInsn); + Value *RetvalShadow = + IRBAfter.CreateAlignedLoad(getShadowPtrForRetval(&I, IRBAfter), + kShadowTLSAlignment, "_msret"); + setShadow(&I, RetvalShadow); + if (MS.TrackOrigins) + setOrigin(&I, IRBAfter.CreateLoad(getOriginPtrForRetval(IRBAfter))); + } + + void visitReturnInst(ReturnInst &I) { + IRBuilder<> IRB(&I); + Value *RetVal = I.getReturnValue(); + if (!RetVal) return; + Value *ShadowPtr = getShadowPtrForRetval(RetVal, IRB); + if (CheckReturnValue) { + insertShadowCheck(RetVal, &I); + Value *Shadow = getCleanShadow(RetVal); + IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment); + } else { + Value *Shadow = getShadow(RetVal); + IRB.CreateAlignedStore(Shadow, ShadowPtr, kShadowTLSAlignment); + // FIXME: make it conditional if ClStoreCleanOrigin==0 + if (MS.TrackOrigins) + IRB.CreateStore(getOrigin(RetVal), getOriginPtrForRetval(IRB)); + } + } + + void visitPHINode(PHINode &I) { + IRBuilder<> IRB(&I); + ShadowPHINodes.push_back(&I); + setShadow(&I, IRB.CreatePHI(getShadowTy(&I), I.getNumIncomingValues(), + "_msphi_s")); + if (MS.TrackOrigins) + setOrigin(&I, IRB.CreatePHI(MS.OriginTy, I.getNumIncomingValues(), + "_msphi_o")); + } + + void visitAllocaInst(AllocaInst &I) { + setShadow(&I, getCleanShadow(&I)); + IRBuilder<> IRB(I.getNextNode()); + uint64_t Size = MS.TD->getTypeAllocSize(I.getAllocatedType()); + if (PoisonStack && ClPoisonStackWithCall) { + IRB.CreateCall2(MS.MsanPoisonStackFn, + IRB.CreatePointerCast(&I, IRB.getInt8PtrTy()), + ConstantInt::get(MS.IntptrTy, Size)); + } else { + Value *ShadowBase = getShadowPtr(&I, Type::getInt8PtrTy(*MS.C), IRB); + Value *PoisonValue = IRB.getInt8(PoisonStack ? ClPoisonStackPattern : 0); + IRB.CreateMemSet(ShadowBase, PoisonValue, Size, I.getAlignment()); + } + + if (PoisonStack && MS.TrackOrigins) { + setOrigin(&I, getCleanOrigin()); + SmallString<2048> StackDescriptionStorage; + raw_svector_ostream StackDescription(StackDescriptionStorage); + // We create a string with a description of the stack allocation and + // pass it into __msan_set_alloca_origin. + // It will be printed by the run-time if stack-originated UMR is found. + // The first 4 bytes of the string are set to '----' and will be replaced + // by __msan_va_arg_overflow_size_tls at the first call. + StackDescription << "----" << I.getName() << "@" << F.getName(); + Value *Descr = + createPrivateNonConstGlobalForString(*F.getParent(), + StackDescription.str()); + + IRB.CreateCall4(MS.MsanSetAllocaOrigin4Fn, + IRB.CreatePointerCast(&I, IRB.getInt8PtrTy()), + ConstantInt::get(MS.IntptrTy, Size), + IRB.CreatePointerCast(Descr, IRB.getInt8PtrTy()), + IRB.CreatePointerCast(&F, MS.IntptrTy)); + } + } + + void visitSelectInst(SelectInst& I) { + IRBuilder<> IRB(&I); + // a = select b, c, d + Value *S = IRB.CreateSelect(I.getCondition(), getShadow(I.getTrueValue()), + getShadow(I.getFalseValue())); + if (I.getType()->isAggregateType()) { + // To avoid "sign extending" i1 to an arbitrary aggregate type, we just do + // an extra "select". This results in much more compact IR. + // Sa = select Sb, poisoned, (select b, Sc, Sd) + S = IRB.CreateSelect(getShadow(I.getCondition()), + getPoisonedShadow(getShadowTy(I.getType())), S, + "_msprop_select_agg"); + } else { + // Sa = (sext Sb) | (select b, Sc, Sd) + S = IRB.CreateOr(S, CreateShadowCast(IRB, getShadow(I.getCondition()), + S->getType(), true), + "_msprop_select"); + } + setShadow(&I, S); + if (MS.TrackOrigins) { + // Origins are always i32, so any vector conditions must be flattened. + // FIXME: consider tracking vector origins for app vectors? + Value *Cond = I.getCondition(); + if (Cond->getType()->isVectorTy()) { + Value *ConvertedShadow = convertToShadowTyNoVec(Cond, IRB); + Cond = IRB.CreateICmpNE(ConvertedShadow, + getCleanShadow(ConvertedShadow), "_mso_select"); + } + setOrigin(&I, IRB.CreateSelect(Cond, + getOrigin(I.getTrueValue()), getOrigin(I.getFalseValue()))); + } + } + + void visitLandingPadInst(LandingPadInst &I) { + // Do nothing. + // See http://code.google.com/p/memory-sanitizer/issues/detail?id=1 + setShadow(&I, getCleanShadow(&I)); + setOrigin(&I, getCleanOrigin()); + } + + void visitGetElementPtrInst(GetElementPtrInst &I) { + handleShadowOr(I); + } + + void visitExtractValueInst(ExtractValueInst &I) { + IRBuilder<> IRB(&I); + Value *Agg = I.getAggregateOperand(); + DEBUG(dbgs() << "ExtractValue: " << I << "\n"); + Value *AggShadow = getShadow(Agg); + DEBUG(dbgs() << " AggShadow: " << *AggShadow << "\n"); + Value *ResShadow = IRB.CreateExtractValue(AggShadow, I.getIndices()); + DEBUG(dbgs() << " ResShadow: " << *ResShadow << "\n"); + setShadow(&I, ResShadow); + setOriginForNaryOp(I); + } + + void visitInsertValueInst(InsertValueInst &I) { + IRBuilder<> IRB(&I); + DEBUG(dbgs() << "InsertValue: " << I << "\n"); + Value *AggShadow = getShadow(I.getAggregateOperand()); + Value *InsShadow = getShadow(I.getInsertedValueOperand()); + DEBUG(dbgs() << " AggShadow: " << *AggShadow << "\n"); + DEBUG(dbgs() << " InsShadow: " << *InsShadow << "\n"); + Value *Res = IRB.CreateInsertValue(AggShadow, InsShadow, I.getIndices()); + DEBUG(dbgs() << " Res: " << *Res << "\n"); + setShadow(&I, Res); + setOriginForNaryOp(I); + } + + void dumpInst(Instruction &I) { + if (CallInst *CI = dyn_cast<CallInst>(&I)) { + errs() << "ZZZ call " << CI->getCalledFunction()->getName() << "\n"; + } else { + errs() << "ZZZ " << I.getOpcodeName() << "\n"; + } + errs() << "QQQ " << I << "\n"; + } + + void visitResumeInst(ResumeInst &I) { + DEBUG(dbgs() << "Resume: " << I << "\n"); + // Nothing to do here. + } + + void visitInstruction(Instruction &I) { + // Everything else: stop propagating and check for poisoned shadow. + if (ClDumpStrictInstructions) + dumpInst(I); + DEBUG(dbgs() << "DEFAULT: " << I << "\n"); + for (size_t i = 0, n = I.getNumOperands(); i < n; i++) + insertShadowCheck(I.getOperand(i), &I); + setShadow(&I, getCleanShadow(&I)); + setOrigin(&I, getCleanOrigin()); + } +}; + +/// \brief AMD64-specific implementation of VarArgHelper. +struct VarArgAMD64Helper : public VarArgHelper { + // An unfortunate workaround for asymmetric lowering of va_arg stuff. + // See a comment in visitCallSite for more details. + static const unsigned AMD64GpEndOffset = 48; // AMD64 ABI Draft 0.99.6 p3.5.7 + static const unsigned AMD64FpEndOffset = 176; + + Function &F; + MemorySanitizer &MS; + MemorySanitizerVisitor &MSV; + Value *VAArgTLSCopy; + Value *VAArgOverflowSize; + + SmallVector<CallInst*, 16> VAStartInstrumentationList; + + VarArgAMD64Helper(Function &F, MemorySanitizer &MS, + MemorySanitizerVisitor &MSV) + : F(F), MS(MS), MSV(MSV), VAArgTLSCopy(0), VAArgOverflowSize(0) { } + + enum ArgKind { AK_GeneralPurpose, AK_FloatingPoint, AK_Memory }; + + ArgKind classifyArgument(Value* arg) { + // A very rough approximation of X86_64 argument classification rules. + Type *T = arg->getType(); + if (T->isFPOrFPVectorTy() || T->isX86_MMXTy()) + return AK_FloatingPoint; + if (T->isIntegerTy() && T->getPrimitiveSizeInBits() <= 64) + return AK_GeneralPurpose; + if (T->isPointerTy()) + return AK_GeneralPurpose; + return AK_Memory; + } + + // For VarArg functions, store the argument shadow in an ABI-specific format + // that corresponds to va_list layout. + // We do this because Clang lowers va_arg in the frontend, and this pass + // only sees the low level code that deals with va_list internals. + // A much easier alternative (provided that Clang emits va_arg instructions) + // would have been to associate each live instance of va_list with a copy of + // MSanParamTLS, and extract shadow on va_arg() call in the argument list + // order. + void visitCallSite(CallSite &CS, IRBuilder<> &IRB) { + unsigned GpOffset = 0; + unsigned FpOffset = AMD64GpEndOffset; + unsigned OverflowOffset = AMD64FpEndOffset; + for (CallSite::arg_iterator ArgIt = CS.arg_begin(), End = CS.arg_end(); + ArgIt != End; ++ArgIt) { + Value *A = *ArgIt; + ArgKind AK = classifyArgument(A); + if (AK == AK_GeneralPurpose && GpOffset >= AMD64GpEndOffset) + AK = AK_Memory; + if (AK == AK_FloatingPoint && FpOffset >= AMD64FpEndOffset) + AK = AK_Memory; + Value *Base; + switch (AK) { + case AK_GeneralPurpose: + Base = getShadowPtrForVAArgument(A, IRB, GpOffset); + GpOffset += 8; + break; + case AK_FloatingPoint: + Base = getShadowPtrForVAArgument(A, IRB, FpOffset); + FpOffset += 16; + break; + case AK_Memory: + uint64_t ArgSize = MS.TD->getTypeAllocSize(A->getType()); + Base = getShadowPtrForVAArgument(A, IRB, OverflowOffset); + OverflowOffset += DataLayout::RoundUpAlignment(ArgSize, 8); + } + IRB.CreateAlignedStore(MSV.getShadow(A), Base, kShadowTLSAlignment); + } + Constant *OverflowSize = + ConstantInt::get(IRB.getInt64Ty(), OverflowOffset - AMD64FpEndOffset); + IRB.CreateStore(OverflowSize, MS.VAArgOverflowSizeTLS); + } + + /// \brief Compute the shadow address for a given va_arg. + Value *getShadowPtrForVAArgument(Value *A, IRBuilder<> &IRB, + int ArgOffset) { + Value *Base = IRB.CreatePointerCast(MS.VAArgTLS, MS.IntptrTy); + Base = IRB.CreateAdd(Base, ConstantInt::get(MS.IntptrTy, ArgOffset)); + return IRB.CreateIntToPtr(Base, PointerType::get(MSV.getShadowTy(A), 0), + "_msarg"); + } + + void visitVAStartInst(VAStartInst &I) { + IRBuilder<> IRB(&I); + VAStartInstrumentationList.push_back(&I); + Value *VAListTag = I.getArgOperand(0); + Value *ShadowPtr = MSV.getShadowPtr(VAListTag, IRB.getInt8Ty(), IRB); + + // Unpoison the whole __va_list_tag. + // FIXME: magic ABI constants. + IRB.CreateMemSet(ShadowPtr, Constant::getNullValue(IRB.getInt8Ty()), + /* size */24, /* alignment */8, false); + } + + void visitVACopyInst(VACopyInst &I) { + IRBuilder<> IRB(&I); + Value *VAListTag = I.getArgOperand(0); + Value *ShadowPtr = MSV.getShadowPtr(VAListTag, IRB.getInt8Ty(), IRB); + + // Unpoison the whole __va_list_tag. + // FIXME: magic ABI constants. + IRB.CreateMemSet(ShadowPtr, Constant::getNullValue(IRB.getInt8Ty()), + /* size */24, /* alignment */8, false); + } + + void finalizeInstrumentation() { + assert(!VAArgOverflowSize && !VAArgTLSCopy && + "finalizeInstrumentation called twice"); + if (!VAStartInstrumentationList.empty()) { + // If there is a va_start in this function, make a backup copy of + // va_arg_tls somewhere in the function entry block. + IRBuilder<> IRB(F.getEntryBlock().getFirstNonPHI()); + VAArgOverflowSize = IRB.CreateLoad(MS.VAArgOverflowSizeTLS); + Value *CopySize = + IRB.CreateAdd(ConstantInt::get(MS.IntptrTy, AMD64FpEndOffset), + VAArgOverflowSize); + VAArgTLSCopy = IRB.CreateAlloca(Type::getInt8Ty(*MS.C), CopySize); + IRB.CreateMemCpy(VAArgTLSCopy, MS.VAArgTLS, CopySize, 8); + } + + // Instrument va_start. + // Copy va_list shadow from the backup copy of the TLS contents. + for (size_t i = 0, n = VAStartInstrumentationList.size(); i < n; i++) { + CallInst *OrigInst = VAStartInstrumentationList[i]; + IRBuilder<> IRB(OrigInst->getNextNode()); + Value *VAListTag = OrigInst->getArgOperand(0); + + Value *RegSaveAreaPtrPtr = + IRB.CreateIntToPtr( + IRB.CreateAdd(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy), + ConstantInt::get(MS.IntptrTy, 16)), + Type::getInt64PtrTy(*MS.C)); + Value *RegSaveAreaPtr = IRB.CreateLoad(RegSaveAreaPtrPtr); + Value *RegSaveAreaShadowPtr = + MSV.getShadowPtr(RegSaveAreaPtr, IRB.getInt8Ty(), IRB); + IRB.CreateMemCpy(RegSaveAreaShadowPtr, VAArgTLSCopy, + AMD64FpEndOffset, 16); + + Value *OverflowArgAreaPtrPtr = + IRB.CreateIntToPtr( + IRB.CreateAdd(IRB.CreatePtrToInt(VAListTag, MS.IntptrTy), + ConstantInt::get(MS.IntptrTy, 8)), + Type::getInt64PtrTy(*MS.C)); + Value *OverflowArgAreaPtr = IRB.CreateLoad(OverflowArgAreaPtrPtr); + Value *OverflowArgAreaShadowPtr = + MSV.getShadowPtr(OverflowArgAreaPtr, IRB.getInt8Ty(), IRB); + Value *SrcPtr = IRB.CreateConstGEP1_32(VAArgTLSCopy, AMD64FpEndOffset); + IRB.CreateMemCpy(OverflowArgAreaShadowPtr, SrcPtr, VAArgOverflowSize, 16); + } + } +}; + +/// \brief A no-op implementation of VarArgHelper. +struct VarArgNoOpHelper : public VarArgHelper { + VarArgNoOpHelper(Function &F, MemorySanitizer &MS, + MemorySanitizerVisitor &MSV) {} + + void visitCallSite(CallSite &CS, IRBuilder<> &IRB) {} + + void visitVAStartInst(VAStartInst &I) {} + + void visitVACopyInst(VACopyInst &I) {} + + void finalizeInstrumentation() {} +}; + +VarArgHelper *CreateVarArgHelper(Function &Func, MemorySanitizer &Msan, + MemorySanitizerVisitor &Visitor) { + // VarArg handling is only implemented on AMD64. False positives are possible + // on other platforms. + llvm::Triple TargetTriple(Func.getParent()->getTargetTriple()); + if (TargetTriple.getArch() == llvm::Triple::x86_64) + return new VarArgAMD64Helper(Func, Msan, Visitor); + else + return new VarArgNoOpHelper(Func, Msan, Visitor); +} + +} // namespace + +bool MemorySanitizer::runOnFunction(Function &F) { + MemorySanitizerVisitor Visitor(F, *this); + + // Clear out readonly/readnone attributes. + AttrBuilder B; + B.addAttribute(Attribute::ReadOnly) + .addAttribute(Attribute::ReadNone); + F.removeAttributes(AttributeSet::FunctionIndex, + AttributeSet::get(F.getContext(), + AttributeSet::FunctionIndex, B)); + + return Visitor.runOnFunction(); +} |