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llvm-project/llvm/lib/Transforms/Instrumentation/EfficiencySanitizer.cpp

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//===-- EfficiencySanitizer.cpp - performance tuner -----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is a part of EfficiencySanitizer, a family of performance tuners
// that detects multiple performance issues via separate sub-tools.
//
// The instrumentation phase is straightforward:
// - Take action on every memory access: either inlined instrumentation,
// or Inserted calls to our run-time library.
// - Optimizations may apply to avoid instrumenting some of the accesses.
// - Turn mem{set,cpy,move} instrinsics into library calls.
// The rest is handled by the run-time library.
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Instrumentation.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/Support/CommandLine.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"
using namespace llvm;
#define DEBUG_TYPE "esan"
// The tool type must be just one of these ClTool* options, as the tools
// cannot be combined due to shadow memory constraints.
static cl::opt<bool>
ClToolCacheFrag("esan-cache-frag", cl::init(false),
cl::desc("Detect data cache fragmentation"), cl::Hidden);
static cl::opt<bool>
ClToolWorkingSet("esan-working-set", cl::init(false),
cl::desc("Measure the working set size"), cl::Hidden);
// Each new tool will get its own opt flag here.
// These are converted to EfficiencySanitizerOptions for use
// in the code.
static cl::opt<bool> ClInstrumentLoadsAndStores(
"esan-instrument-loads-and-stores", cl::init(true),
cl::desc("Instrument loads and stores"), cl::Hidden);
static cl::opt<bool> ClInstrumentMemIntrinsics(
"esan-instrument-memintrinsics", cl::init(true),
cl::desc("Instrument memintrinsics (memset/memcpy/memmove)"), cl::Hidden);
static cl::opt<bool> ClInstrumentFastpath(
"esan-instrument-fastpath", cl::init(true),
cl::desc("Instrument fastpath"), cl::Hidden);
// Experiments show that the performance difference can be 2x or more,
// and accuracy loss is typically negligible, so we turn this on by default.
static cl::opt<bool> ClAssumeIntraCacheLine(
"esan-assume-intra-cache-line", cl::init(true),
cl::desc("Assume each memory access touches just one cache line, for "
"better performance but with a potential loss of accuracy."),
cl::Hidden);
STATISTIC(NumInstrumentedLoads, "Number of instrumented loads");
STATISTIC(NumInstrumentedStores, "Number of instrumented stores");
STATISTIC(NumFastpaths, "Number of instrumented fastpaths");
STATISTIC(NumAccessesWithIrregularSize,
"Number of accesses with a size outside our targeted callout sizes");
STATISTIC(NumIgnoredStructs, "Number of ignored structs");
STATISTIC(NumIgnoredGEPs, "Number of ignored GEP instructions");
STATISTIC(NumInstrumentedGEPs, "Number of instrumented GEP instructions");
STATISTIC(NumAssumedIntraCacheLine,
"Number of accesses assumed to be intra-cache-line");
static const uint64_t EsanCtorAndDtorPriority = 0;
static const char *const EsanModuleCtorName = "esan.module_ctor";
static const char *const EsanModuleDtorName = "esan.module_dtor";
static const char *const EsanInitName = "__esan_init";
static const char *const EsanExitName = "__esan_exit";
// We need to specify the tool to the runtime earlier than
// the ctor is called in some cases, so we set a global variable.
static const char *const EsanWhichToolName = "__esan_which_tool";
// We must keep these Shadow* constants consistent with the esan runtime.
// FIXME: Try to place these shadow constants, the names of the __esan_*
// interface functions, and the ToolType enum into a header shared between
// llvm and compiler-rt.
static const uint64_t ShadowMask = 0x00000fffffffffffull;
static const uint64_t ShadowOffs[3] = { // Indexed by scale
0x0000130000000000ull,
0x0000220000000000ull,
0x0000440000000000ull,
};
// This array is indexed by the ToolType enum.
static const int ShadowScale[] = {
0, // ESAN_None.
2, // ESAN_CacheFrag: 4B:1B, so 4 to 1 == >>2.
6, // ESAN_WorkingSet: 64B:1B, so 64 to 1 == >>6.
};
// MaxStructCounterNameSize is a soft size limit to avoid insanely long
// names for those extremely large structs.
static const unsigned MaxStructCounterNameSize = 512;
namespace {
static EfficiencySanitizerOptions
OverrideOptionsFromCL(EfficiencySanitizerOptions Options) {
if (ClToolCacheFrag)
Options.ToolType = EfficiencySanitizerOptions::ESAN_CacheFrag;
else if (ClToolWorkingSet)
Options.ToolType = EfficiencySanitizerOptions::ESAN_WorkingSet;
// Direct opt invocation with no params will have the default ESAN_None.
// We run the default tool in that case.
if (Options.ToolType == EfficiencySanitizerOptions::ESAN_None)
Options.ToolType = EfficiencySanitizerOptions::ESAN_CacheFrag;
return Options;
}
// Create a constant for Str so that we can pass it to the run-time lib.
static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
bool AllowMerging) {
Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
// We use private linkage for module-local strings. If they can be merged
// with another one, we set the unnamed_addr attribute.
GlobalVariable *GV =
new GlobalVariable(M, StrConst->getType(), true,
GlobalValue::PrivateLinkage, StrConst, "");
if (AllowMerging)
GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
return GV;
}
/// EfficiencySanitizer: instrument each module to find performance issues.
class EfficiencySanitizer : public ModulePass {
public:
EfficiencySanitizer(
const EfficiencySanitizerOptions &Opts = EfficiencySanitizerOptions())
: ModulePass(ID), Options(OverrideOptionsFromCL(Opts)) {}
const char *getPassName() const override;
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnModule(Module &M) override;
static char ID;
private:
bool initOnModule(Module &M);
void initializeCallbacks(Module &M);
bool shouldIgnoreStructType(StructType *StructTy);
void createStructCounterName(
StructType *StructTy, SmallString<MaxStructCounterNameSize> &NameStr);
GlobalVariable *createCacheFragInfoGV(Module &M, const DataLayout &DL,
Constant *UnitName);
Constant *createEsanInitToolInfoArg(Module &M, const DataLayout &DL);
void createDestructor(Module &M, Constant *ToolInfoArg);
bool runOnFunction(Function &F, Module &M);
bool instrumentLoadOrStore(Instruction *I, const DataLayout &DL);
bool instrumentMemIntrinsic(MemIntrinsic *MI);
bool instrumentGetElementPtr(Instruction *I, Module &M);
bool shouldIgnoreMemoryAccess(Instruction *I);
int getMemoryAccessFuncIndex(Value *Addr, const DataLayout &DL);
Value *appToShadow(Value *Shadow, IRBuilder<> &IRB);
bool instrumentFastpath(Instruction *I, const DataLayout &DL, bool IsStore,
Value *Addr, unsigned Alignment);
// Each tool has its own fastpath routine:
bool instrumentFastpathCacheFrag(Instruction *I, const DataLayout &DL,
Value *Addr, unsigned Alignment);
bool instrumentFastpathWorkingSet(Instruction *I, const DataLayout &DL,
Value *Addr, unsigned Alignment);
EfficiencySanitizerOptions Options;
LLVMContext *Ctx;
Type *IntptrTy;
// Our slowpath involves callouts to the runtime library.
// Access sizes are powers of two: 1, 2, 4, 8, 16.
static const size_t NumberOfAccessSizes = 5;
Function *EsanAlignedLoad[NumberOfAccessSizes];
Function *EsanAlignedStore[NumberOfAccessSizes];
Function *EsanUnalignedLoad[NumberOfAccessSizes];
Function *EsanUnalignedStore[NumberOfAccessSizes];
// For irregular sizes of any alignment:
Function *EsanUnalignedLoadN, *EsanUnalignedStoreN;
Function *MemmoveFn, *MemcpyFn, *MemsetFn;
Function *EsanCtorFunction;
Function *EsanDtorFunction;
// Remember the counter variable for each struct type to avoid
// recomputing the variable name later during instrumentation.
std::map<Type *, GlobalVariable *> StructTyMap;
};
} // namespace
char EfficiencySanitizer::ID = 0;
INITIALIZE_PASS_BEGIN(
EfficiencySanitizer, "esan",
"EfficiencySanitizer: finds performance issues.", false, false)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_END(
EfficiencySanitizer, "esan",
"EfficiencySanitizer: finds performance issues.", false, false)
const char *EfficiencySanitizer::getPassName() const {
return "EfficiencySanitizer";
}
void EfficiencySanitizer::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addRequired<TargetLibraryInfoWrapperPass>();
}
ModulePass *
llvm::createEfficiencySanitizerPass(const EfficiencySanitizerOptions &Options) {
return new EfficiencySanitizer(Options);
}
void EfficiencySanitizer::initializeCallbacks(Module &M) {
IRBuilder<> IRB(M.getContext());
// Initialize the callbacks.
for (size_t Idx = 0; Idx < NumberOfAccessSizes; ++Idx) {
const unsigned ByteSize = 1U << Idx;
std::string ByteSizeStr = utostr(ByteSize);
// We'll inline the most common (i.e., aligned and frequent sizes)
// load + store instrumentation: these callouts are for the slowpath.
SmallString<32> AlignedLoadName("__esan_aligned_load" + ByteSizeStr);
EsanAlignedLoad[Idx] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
AlignedLoadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
SmallString<32> AlignedStoreName("__esan_aligned_store" + ByteSizeStr);
EsanAlignedStore[Idx] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
AlignedStoreName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
SmallString<32> UnalignedLoadName("__esan_unaligned_load" + ByteSizeStr);
EsanUnalignedLoad[Idx] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
UnalignedLoadName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
SmallString<32> UnalignedStoreName("__esan_unaligned_store" + ByteSizeStr);
EsanUnalignedStore[Idx] =
checkSanitizerInterfaceFunction(M.getOrInsertFunction(
UnalignedStoreName, IRB.getVoidTy(), IRB.getInt8PtrTy(), nullptr));
}
EsanUnalignedLoadN = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("__esan_unaligned_loadN", IRB.getVoidTy(),
IRB.getInt8PtrTy(), IntptrTy, nullptr));
EsanUnalignedStoreN = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("__esan_unaligned_storeN", IRB.getVoidTy(),
IRB.getInt8PtrTy(), IntptrTy, nullptr));
MemmoveFn = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("memmove", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IntptrTy, nullptr));
MemcpyFn = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("memcpy", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IRB.getInt8PtrTy(), IntptrTy, nullptr));
MemsetFn = checkSanitizerInterfaceFunction(
M.getOrInsertFunction("memset", IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
IRB.getInt32Ty(), IntptrTy, nullptr));
}
bool EfficiencySanitizer::shouldIgnoreStructType(StructType *StructTy) {
if (StructTy == nullptr || StructTy->isOpaque() /* no struct body */)
return true;
return false;
}
void EfficiencySanitizer::createStructCounterName(
StructType *StructTy, SmallString<MaxStructCounterNameSize> &NameStr) {
// Append NumFields and field type ids to avoid struct conflicts
// with the same name but different fields.
if (StructTy->hasName())
NameStr += StructTy->getName();
else
NameStr += "struct.anon";
// We allow the actual size of the StructCounterName to be larger than
// MaxStructCounterNameSize and append #NumFields and at least one
// field type id.
// Append #NumFields.
NameStr += "#";
Twine(StructTy->getNumElements()).toVector(NameStr);
// Append struct field type ids in the reverse order.
for (int i = StructTy->getNumElements() - 1; i >= 0; --i) {
NameStr += "#";
Twine(StructTy->getElementType(i)->getTypeID()).toVector(NameStr);
if (NameStr.size() >= MaxStructCounterNameSize)
break;
}
if (StructTy->isLiteral()) {
// End with # for literal struct.
NameStr += "#";
}
}
// Create the global variable for the cache-fragmentation tool.
GlobalVariable *EfficiencySanitizer::createCacheFragInfoGV(
Module &M, const DataLayout &DL, Constant *UnitName) {
assert(Options.ToolType == EfficiencySanitizerOptions::ESAN_CacheFrag);
auto *Int8PtrTy = Type::getInt8PtrTy(*Ctx);
auto *Int8PtrPtrTy = Int8PtrTy->getPointerTo();
auto *Int32Ty = Type::getInt32Ty(*Ctx);
auto *Int32PtrTy = Type::getInt32PtrTy(*Ctx);
auto *Int64Ty = Type::getInt64Ty(*Ctx);
auto *Int64PtrTy = Type::getInt64PtrTy(*Ctx);
// This structure should be kept consistent with the StructInfo struct
// in the runtime library.
// struct StructInfo {
// const char *StructName;
// u32 Size;
// u32 NumFields;
// u32 *FieldOffsets;
// u32 *FieldSize;
// u64 *FieldCounters;
// const char **FieldTypeNames;
// };
auto *StructInfoTy =
StructType::get(Int8PtrTy, Int32Ty, Int32Ty, Int32PtrTy, Int32PtrTy,
Int64PtrTy, Int8PtrPtrTy, nullptr);
auto *StructInfoPtrTy = StructInfoTy->getPointerTo();
// This structure should be kept consistent with the CacheFragInfo struct
// in the runtime library.
// struct CacheFragInfo {
// const char *UnitName;
// u32 NumStructs;
// StructInfo *Structs;
// };
auto *CacheFragInfoTy =
StructType::get(Int8PtrTy, Int32Ty, StructInfoPtrTy, nullptr);
std::vector<StructType *> Vec = M.getIdentifiedStructTypes();
unsigned NumStructs = 0;
SmallVector<Constant *, 16> Initializers;
for (auto &StructTy : Vec) {
if (shouldIgnoreStructType(StructTy)) {
++NumIgnoredStructs;
continue;
}
++NumStructs;
// StructName.
SmallString<MaxStructCounterNameSize> CounterNameStr;
createStructCounterName(StructTy, CounterNameStr);
GlobalVariable *StructCounterName = createPrivateGlobalForString(
M, CounterNameStr, /*AllowMerging*/true);
// FieldCounters.
// We create the counter array with StructCounterName and weak linkage
// so that the structs with the same name and layout from different
// compilation units will be merged into one.
auto *CounterArrayTy = ArrayType::get(Int64Ty, StructTy->getNumElements());
GlobalVariable *Counters =
new GlobalVariable(M, CounterArrayTy, false,
GlobalVariable::WeakAnyLinkage,
ConstantAggregateZero::get(CounterArrayTy),
CounterNameStr);
// Remember the counter variable for each struct type.
StructTyMap.insert(std::pair<Type *, GlobalVariable *>(StructTy, Counters));
// We pass the field type name array and offset array to the runtime for
// better reporting.
// FieldTypeNames.
auto *TypeNameArrayTy = ArrayType::get(Int8PtrTy, StructTy->getNumElements());
GlobalVariable *TypeNames =
new GlobalVariable(M, TypeNameArrayTy, true,
GlobalVariable::InternalLinkage, nullptr);
SmallVector<Constant *, 16> TypeNameVec;
// FieldOffsets.
const StructLayout *SL = DL.getStructLayout(StructTy);
auto *OffsetArrayTy = ArrayType::get(Int32Ty, StructTy->getNumElements());
GlobalVariable *Offsets =
new GlobalVariable(M, OffsetArrayTy, true,
GlobalVariable::InternalLinkage, nullptr);
SmallVector<Constant *, 16> OffsetVec;
// FieldSize
auto *SizeArrayTy = ArrayType::get(Int32Ty, StructTy->getNumElements());
GlobalVariable *Size =
new GlobalVariable(M, SizeArrayTy, true,
GlobalVariable::InternalLinkage, nullptr);
SmallVector<Constant *, 16> SizeVec;
for (unsigned i = 0; i < StructTy->getNumElements(); ++i) {
Type *Ty = StructTy->getElementType(i);
std::string Str;
raw_string_ostream StrOS(Str);
Ty->print(StrOS);
TypeNameVec.push_back(
ConstantExpr::getPointerCast(
createPrivateGlobalForString(M, StrOS.str(), true),
Int8PtrTy));
OffsetVec.push_back(ConstantInt::get(Int32Ty, SL->getElementOffset(i)));
SizeVec.push_back(ConstantInt::get(Int32Ty,
DL.getTypeAllocSize(Ty)));
}
TypeNames->setInitializer(ConstantArray::get(TypeNameArrayTy, TypeNameVec));
Offsets->setInitializer(ConstantArray::get(OffsetArrayTy, OffsetVec));
Size->setInitializer(ConstantArray::get(SizeArrayTy, SizeVec));
Initializers.push_back(
ConstantStruct::get(
StructInfoTy,
ConstantExpr::getPointerCast(StructCounterName, Int8PtrTy),
ConstantInt::get(Int32Ty, SL->getSizeInBytes()),
ConstantInt::get(Int32Ty, StructTy->getNumElements()),
ConstantExpr::getPointerCast(Offsets, Int32PtrTy),
ConstantExpr::getPointerCast(Size, Int32PtrTy),
ConstantExpr::getPointerCast(Counters, Int64PtrTy),
ConstantExpr::getPointerCast(TypeNames, Int8PtrPtrTy),
nullptr));
}
// Structs.
Constant *StructInfo;
if (NumStructs == 0) {
StructInfo = ConstantPointerNull::get(StructInfoPtrTy);
} else {
auto *StructInfoArrayTy = ArrayType::get(StructInfoTy, NumStructs);
StructInfo = ConstantExpr::getPointerCast(
new GlobalVariable(M, StructInfoArrayTy, false,
GlobalVariable::InternalLinkage,
ConstantArray::get(StructInfoArrayTy, Initializers)),
StructInfoPtrTy);
}
auto *CacheFragInfoGV = new GlobalVariable(
M, CacheFragInfoTy, true, GlobalVariable::InternalLinkage,
ConstantStruct::get(CacheFragInfoTy,
UnitName,
ConstantInt::get(Int32Ty, NumStructs),
StructInfo,
nullptr));
return CacheFragInfoGV;
}
// Create the tool-specific argument passed to EsanInit and EsanExit.
Constant *EfficiencySanitizer::createEsanInitToolInfoArg(Module &M,
const DataLayout &DL) {
// This structure contains tool-specific information about each compilation
// unit (module) and is passed to the runtime library.
GlobalVariable *ToolInfoGV = nullptr;
auto *Int8PtrTy = Type::getInt8PtrTy(*Ctx);
// Compilation unit name.
auto *UnitName = ConstantExpr::getPointerCast(
createPrivateGlobalForString(M, M.getModuleIdentifier(), true),
Int8PtrTy);
// Create the tool-specific variable.
if (Options.ToolType == EfficiencySanitizerOptions::ESAN_CacheFrag)
ToolInfoGV = createCacheFragInfoGV(M, DL, UnitName);
if (ToolInfoGV != nullptr)
return ConstantExpr::getPointerCast(ToolInfoGV, Int8PtrTy);
// Create the null pointer if no tool-specific variable created.
return ConstantPointerNull::get(Int8PtrTy);
}
void EfficiencySanitizer::createDestructor(Module &M, Constant *ToolInfoArg) {
PointerType *Int8PtrTy = Type::getInt8PtrTy(*Ctx);
EsanDtorFunction = Function::Create(FunctionType::get(Type::getVoidTy(*Ctx),
false),
GlobalValue::InternalLinkage,
EsanModuleDtorName, &M);
ReturnInst::Create(*Ctx, BasicBlock::Create(*Ctx, "", EsanDtorFunction));
IRBuilder<> IRB_Dtor(EsanDtorFunction->getEntryBlock().getTerminator());
Function *EsanExit = checkSanitizerInterfaceFunction(
M.getOrInsertFunction(EsanExitName, IRB_Dtor.getVoidTy(),
Int8PtrTy, nullptr));
EsanExit->setLinkage(Function::ExternalLinkage);
IRB_Dtor.CreateCall(EsanExit, {ToolInfoArg});
appendToGlobalDtors(M, EsanDtorFunction, EsanCtorAndDtorPriority);
}
bool EfficiencySanitizer::initOnModule(Module &M) {
Ctx = &M.getContext();
const DataLayout &DL = M.getDataLayout();
IRBuilder<> IRB(M.getContext());
IntegerType *OrdTy = IRB.getInt32Ty();
PointerType *Int8PtrTy = Type::getInt8PtrTy(*Ctx);
IntptrTy = DL.getIntPtrType(M.getContext());
// Create the variable passed to EsanInit and EsanExit.
Constant *ToolInfoArg = createEsanInitToolInfoArg(M, DL);
// Constructor
// We specify the tool type both in the EsanWhichToolName global
// and as an arg to the init routine as a sanity check.
std::tie(EsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
M, EsanModuleCtorName, EsanInitName, /*InitArgTypes=*/{OrdTy, Int8PtrTy},
/*InitArgs=*/{
ConstantInt::get(OrdTy, static_cast<int>(Options.ToolType)),
ToolInfoArg});
appendToGlobalCtors(M, EsanCtorFunction, EsanCtorAndDtorPriority);
createDestructor(M, ToolInfoArg);
new GlobalVariable(M, OrdTy, true,
GlobalValue::WeakAnyLinkage,
ConstantInt::get(OrdTy,
static_cast<int>(Options.ToolType)),
EsanWhichToolName);
return true;
}
Value *EfficiencySanitizer::appToShadow(Value *Shadow, IRBuilder<> &IRB) {
// Shadow = ((App & Mask) + Offs) >> Scale
Shadow = IRB.CreateAnd(Shadow, ConstantInt::get(IntptrTy, ShadowMask));
uint64_t Offs;
int Scale = ShadowScale[Options.ToolType];
if (Scale <= 2)
Offs = ShadowOffs[Scale];
else
Offs = ShadowOffs[0] << Scale;
Shadow = IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Offs));
if (Scale > 0)
Shadow = IRB.CreateLShr(Shadow, Scale);
return Shadow;
}
bool EfficiencySanitizer::shouldIgnoreMemoryAccess(Instruction *I) {
if (Options.ToolType == EfficiencySanitizerOptions::ESAN_CacheFrag) {
// We'd like to know about cache fragmentation in vtable accesses and
// constant data references, so we do not currently ignore anything.
return false;
} else if (Options.ToolType == EfficiencySanitizerOptions::ESAN_WorkingSet) {
// TODO: the instrumentation disturbs the data layout on the stack, so we
// may want to add an option to ignore stack references (if we can
// distinguish them) to reduce overhead.
}
// TODO(bruening): future tools will be returning true for some cases.
return false;
}
bool EfficiencySanitizer::runOnModule(Module &M) {
bool Res = initOnModule(M);
initializeCallbacks(M);
for (auto &F : M) {
Res |= runOnFunction(F, M);
}
return Res;
}
bool EfficiencySanitizer::runOnFunction(Function &F, Module &M) {
// This is required to prevent instrumenting the call to __esan_init from
// within the module constructor.
if (&F == EsanCtorFunction)
return false;
SmallVector<Instruction *, 8> LoadsAndStores;
SmallVector<Instruction *, 8> MemIntrinCalls;
SmallVector<Instruction *, 8> GetElementPtrs;
bool Res = false;
const DataLayout &DL = M.getDataLayout();
const TargetLibraryInfo *TLI =
&getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
for (auto &BB : F) {
for (auto &Inst : BB) {
if ((isa<LoadInst>(Inst) || isa<StoreInst>(Inst) ||
isa<AtomicRMWInst>(Inst) || isa<AtomicCmpXchgInst>(Inst)) &&
!shouldIgnoreMemoryAccess(&Inst))
LoadsAndStores.push_back(&Inst);
else if (isa<MemIntrinsic>(Inst))
MemIntrinCalls.push_back(&Inst);
else if (isa<GetElementPtrInst>(Inst))
GetElementPtrs.push_back(&Inst);
else if (CallInst *CI = dyn_cast<CallInst>(&Inst))
maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
}
}
if (ClInstrumentLoadsAndStores) {
for (auto Inst : LoadsAndStores) {
Res |= instrumentLoadOrStore(Inst, DL);
}
}
if (ClInstrumentMemIntrinsics) {
for (auto Inst : MemIntrinCalls) {
Res |= instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
}
}
if (Options.ToolType == EfficiencySanitizerOptions::ESAN_CacheFrag) {
for (auto Inst : GetElementPtrs) {
Res |= instrumentGetElementPtr(Inst, M);
}
}
return Res;
}
bool EfficiencySanitizer::instrumentLoadOrStore(Instruction *I,
const DataLayout &DL) {
IRBuilder<> IRB(I);
bool IsStore;
Value *Addr;
unsigned Alignment;
if (LoadInst *Load = dyn_cast<LoadInst>(I)) {
IsStore = false;
Alignment = Load->getAlignment();
Addr = Load->getPointerOperand();
} else if (StoreInst *Store = dyn_cast<StoreInst>(I)) {
IsStore = true;
Alignment = Store->getAlignment();
Addr = Store->getPointerOperand();
} else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
IsStore = true;
Alignment = 0;
Addr = RMW->getPointerOperand();
} else if (AtomicCmpXchgInst *Xchg = dyn_cast<AtomicCmpXchgInst>(I)) {
IsStore = true;
Alignment = 0;
Addr = Xchg->getPointerOperand();
} else
llvm_unreachable("Unsupported mem access type");
Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
const uint32_t TypeSizeBytes = DL.getTypeStoreSizeInBits(OrigTy) / 8;
Value *OnAccessFunc = nullptr;
// Convert 0 to the default alignment.
if (Alignment == 0)
Alignment = DL.getPrefTypeAlignment(OrigTy);
if (IsStore)
NumInstrumentedStores++;
else
NumInstrumentedLoads++;
int Idx = getMemoryAccessFuncIndex(Addr, DL);
if (Idx < 0) {
OnAccessFunc = IsStore ? EsanUnalignedStoreN : EsanUnalignedLoadN;
IRB.CreateCall(OnAccessFunc,
{IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()),
ConstantInt::get(IntptrTy, TypeSizeBytes)});
} else {
if (ClInstrumentFastpath &&
instrumentFastpath(I, DL, IsStore, Addr, Alignment)) {
NumFastpaths++;
return true;
}
if (Alignment == 0 || Alignment >= 8 || (Alignment % TypeSizeBytes) == 0)
OnAccessFunc = IsStore ? EsanAlignedStore[Idx] : EsanAlignedLoad[Idx];
else
OnAccessFunc = IsStore ? EsanUnalignedStore[Idx] : EsanUnalignedLoad[Idx];
IRB.CreateCall(OnAccessFunc,
IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy()));
}
return true;
}
// It's simplest to replace the memset/memmove/memcpy intrinsics with
// calls that the runtime library intercepts.
// Our pass is late enough that calls should not turn back into intrinsics.
bool EfficiencySanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
IRBuilder<> IRB(MI);
bool Res = false;
if (isa<MemSetInst>(MI)) {
IRB.CreateCall(
MemsetFn,
{IRB.CreatePointerCast(MI->getArgOperand(0), IRB.getInt8PtrTy()),
IRB.CreateIntCast(MI->getArgOperand(1), IRB.getInt32Ty(), false),
IRB.CreateIntCast(MI->getArgOperand(2), IntptrTy, false)});
MI->eraseFromParent();
Res = true;
} else if (isa<MemTransferInst>(MI)) {
IRB.CreateCall(
isa<MemCpyInst>(MI) ? MemcpyFn : MemmoveFn,
{IRB.CreatePointerCast(MI->getArgOperand(0), IRB.getInt8PtrTy()),
IRB.CreatePointerCast(MI->getArgOperand(1), IRB.getInt8PtrTy()),
IRB.CreateIntCast(MI->getArgOperand(2), IntptrTy, false)});
MI->eraseFromParent();
Res = true;
} else
llvm_unreachable("Unsupported mem intrinsic type");
return Res;
}
bool EfficiencySanitizer::instrumentGetElementPtr(Instruction *I, Module &M) {
GetElementPtrInst *GepInst = dyn_cast<GetElementPtrInst>(I);
bool Res = false;
if (GepInst == nullptr || GepInst->getNumIndices() == 1) {
++NumIgnoredGEPs;
return false;
}
Type *SourceTy = GepInst->getSourceElementType();
// Iterate all (except the first and the last) idx within each GEP instruction
// for possible nested struct field address calculation.
for (unsigned i = 1; i < GepInst->getNumIndices(); ++i) {
SmallVector<Value *, 8> IdxVec(GepInst->idx_begin(),
GepInst->idx_begin() + i);
StructType *StructTy = dyn_cast<StructType>(
GetElementPtrInst::getIndexedType(SourceTy, IdxVec));
if (StructTy == nullptr || shouldIgnoreStructType(StructTy) ||
StructTyMap.count(StructTy) == 0)
continue;
// Get the StructTy's subfield index.
ConstantInt *Idx = dyn_cast<ConstantInt>(GepInst->getOperand(i+1));
if (Idx == nullptr || Idx->getZExtValue() > StructTy->getNumElements())
continue;
GlobalVariable *CounterArray = StructTyMap[StructTy];
if (CounterArray == nullptr)
return false;
IRBuilder<> IRB(I);
Constant *Indices[2];
// Xref http://llvm.org/docs/LangRef.html#i-getelementptr and
// http://llvm.org/docs/GetElementPtr.html.
// The first index of the GEP instruction steps through the first operand,
// i.e., the array itself.
Indices[0] = ConstantInt::get(IRB.getInt32Ty(), 0);
// The second index is the index within the array.
Indices[1] = ConstantInt::get(IRB.getInt32Ty(), Idx->getZExtValue());
Constant *Counter =
ConstantExpr::getGetElementPtr(
ArrayType::get(IRB.getInt64Ty(), StructTy->getNumElements()),
CounterArray, Indices);
Value *Load = IRB.CreateLoad(Counter);
IRB.CreateStore(IRB.CreateAdd(Load, ConstantInt::get(IRB.getInt64Ty(), 1)),
Counter);
Res = true;
}
if (Res)
++NumInstrumentedGEPs;
else
++NumIgnoredGEPs;
return Res;
}
int EfficiencySanitizer::getMemoryAccessFuncIndex(Value *Addr,
const DataLayout &DL) {
Type *OrigPtrTy = Addr->getType();
Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
assert(OrigTy->isSized());
// The size is always a multiple of 8.
uint32_t TypeSizeBytes = DL.getTypeStoreSizeInBits(OrigTy) / 8;
if (TypeSizeBytes != 1 && TypeSizeBytes != 2 && TypeSizeBytes != 4 &&
TypeSizeBytes != 8 && TypeSizeBytes != 16) {
// Irregular sizes do not have per-size call targets.
NumAccessesWithIrregularSize++;
return -1;
}
size_t Idx = countTrailingZeros(TypeSizeBytes);
assert(Idx < NumberOfAccessSizes);
return Idx;
}
bool EfficiencySanitizer::instrumentFastpath(Instruction *I,
const DataLayout &DL, bool IsStore,
Value *Addr, unsigned Alignment) {
if (Options.ToolType == EfficiencySanitizerOptions::ESAN_CacheFrag) {
return instrumentFastpathCacheFrag(I, DL, Addr, Alignment);
} else if (Options.ToolType == EfficiencySanitizerOptions::ESAN_WorkingSet) {
return instrumentFastpathWorkingSet(I, DL, Addr, Alignment);
}
return false;
}
bool EfficiencySanitizer::instrumentFastpathCacheFrag(Instruction *I,
const DataLayout &DL,
Value *Addr,
unsigned Alignment) {
// Do nothing.
return true; // Return true to avoid slowpath instrumentation.
}
bool EfficiencySanitizer::instrumentFastpathWorkingSet(
Instruction *I, const DataLayout &DL, Value *Addr, unsigned Alignment) {
assert(ShadowScale[Options.ToolType] == 6); // The code below assumes this
IRBuilder<> IRB(I);
Type *OrigTy = cast<PointerType>(Addr->getType())->getElementType();
const uint32_t TypeSize = DL.getTypeStoreSizeInBits(OrigTy);
// Bail to the slowpath if the access might touch multiple cache lines.
// An access aligned to its size is guaranteed to be intra-cache-line.
// getMemoryAccessFuncIndex has already ruled out a size larger than 16
// and thus larger than a cache line for platforms this tool targets
// (and our shadow memory setup assumes 64-byte cache lines).
assert(TypeSize <= 64);
if (!(TypeSize == 8 ||
(Alignment % (TypeSize / 8)) == 0)) {
if (ClAssumeIntraCacheLine)
++NumAssumedIntraCacheLine;
else
return false;
}
// We inline instrumentation to set the corresponding shadow bits for
// each cache line touched by the application. Here we handle a single
// load or store where we've already ruled out the possibility that it
// might touch more than one cache line and thus we simply update the
// shadow memory for a single cache line.
// Our shadow memory model is fine with races when manipulating shadow values.
// We generate the following code:
//
// const char BitMask = 0x81;
// char *ShadowAddr = appToShadow(AppAddr);
// if ((*ShadowAddr & BitMask) != BitMask)
// *ShadowAddr |= Bitmask;
//
Value *AddrPtr = IRB.CreatePointerCast(Addr, IntptrTy);
Value *ShadowPtr = appToShadow(AddrPtr, IRB);
Type *ShadowTy = IntegerType::get(*Ctx, 8U);
Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
// The bottom bit is used for the current sampling period's working set.
// The top bit is used for the total working set. We set both on each
// memory access, if they are not already set.
Value *ValueMask = ConstantInt::get(ShadowTy, 0x81); // 10000001B
Value *OldValue = IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
// The AND and CMP will be turned into a TEST instruction by the compiler.
Value *Cmp = IRB.CreateICmpNE(IRB.CreateAnd(OldValue, ValueMask), ValueMask);
TerminatorInst *CmpTerm = SplitBlockAndInsertIfThen(Cmp, I, false);
// FIXME: do I need to call SetCurrentDebugLocation?
IRB.SetInsertPoint(CmpTerm);
// We use OR to set the shadow bits to avoid corrupting the middle 6 bits,
// which are used by the runtime library.
Value *NewVal = IRB.CreateOr(OldValue, ValueMask);
IRB.CreateStore(NewVal, IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
IRB.SetInsertPoint(I);
return true;
}
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