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llvm-project/llvm/lib/Transforms/Instrumentation/MemProfiler.cpp
Kazu Hirata 51cdf1f662
[memprof] Skip MemProfUsePass on the empty module (#117210) 
This patch teaches the MemProfUsePass to return immediately on
the empty module.

Aside from saving time to deserialize the MemProf profile, this patch
ensures that we can obtain TLI like so:

TargetLibraryInfo &TLI =
FAM.getResult<TargetLibraryAnalysis>(*M.begin());

when we undrift the MemProf profile in near future.
2024-11-21 11:29:48 -08:00

1178 lines
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//===- MemProfiler.cpp - memory allocation and access profiler ------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file is a part of MemProfiler. Memory accesses are instrumented
// to increment the access count held in a shadow memory location, or
// alternatively to call into the runtime. Memory intrinsic calls (memmove,
// memcpy, memset) are changed to call the memory profiling runtime version
// instead.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Instrumentation/MemProfiler.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/MemoryBuiltins.h"
#include "llvm/Analysis/MemoryProfileInfo.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/IR/Constant.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/GlobalValue.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instruction.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Type.h"
#include "llvm/IR/Value.h"
#include "llvm/ProfileData/InstrProf.h"
#include "llvm/ProfileData/InstrProfReader.h"
#include "llvm/Support/BLAKE3.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/HashBuilder.h"
#include "llvm/Support/VirtualFileSystem.h"
#include "llvm/TargetParser/Triple.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/LongestCommonSequence.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include <map>
#include <set>
using namespace llvm;
using namespace llvm::memprof;
#define DEBUG_TYPE "memprof"
namespace llvm {
extern cl::opt<bool> PGOWarnMissing;
extern cl::opt<bool> NoPGOWarnMismatch;
extern cl::opt<bool> NoPGOWarnMismatchComdatWeak;
} // namespace llvm
constexpr int LLVM_MEM_PROFILER_VERSION = 1;
// Size of memory mapped to a single shadow location.
constexpr uint64_t DefaultMemGranularity = 64;
// Size of memory mapped to a single histogram bucket.
constexpr uint64_t HistogramGranularity = 8;
// Scale from granularity down to shadow size.
constexpr uint64_t DefaultShadowScale = 3;
constexpr char MemProfModuleCtorName[] = "memprof.module_ctor";
constexpr uint64_t MemProfCtorAndDtorPriority = 1;
// On Emscripten, the system needs more than one priorities for constructors.
constexpr uint64_t MemProfEmscriptenCtorAndDtorPriority = 50;
constexpr char MemProfInitName[] = "__memprof_init";
constexpr char MemProfVersionCheckNamePrefix[] =
"__memprof_version_mismatch_check_v";
constexpr char MemProfShadowMemoryDynamicAddress[] =
"__memprof_shadow_memory_dynamic_address";
constexpr char MemProfFilenameVar[] = "__memprof_profile_filename";
constexpr char MemProfHistogramFlagVar[] = "__memprof_histogram";
// Command-line flags.
static cl::opt<bool> ClInsertVersionCheck(
"memprof-guard-against-version-mismatch",
cl::desc("Guard against compiler/runtime version mismatch."), cl::Hidden,
cl::init(true));
// This flag may need to be replaced with -f[no-]memprof-reads.
static cl::opt<bool> ClInstrumentReads("memprof-instrument-reads",
cl::desc("instrument read instructions"),
cl::Hidden, cl::init(true));
static cl::opt<bool>
ClInstrumentWrites("memprof-instrument-writes",
cl::desc("instrument write instructions"), cl::Hidden,
cl::init(true));
static cl::opt<bool> ClInstrumentAtomics(
"memprof-instrument-atomics",
cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
cl::init(true));
static cl::opt<bool> ClUseCalls(
"memprof-use-callbacks",
cl::desc("Use callbacks instead of inline instrumentation sequences."),
cl::Hidden, cl::init(false));
static cl::opt<std::string>
ClMemoryAccessCallbackPrefix("memprof-memory-access-callback-prefix",
cl::desc("Prefix for memory access callbacks"),
cl::Hidden, cl::init("__memprof_"));
// These flags allow to change the shadow mapping.
// The shadow mapping looks like
// Shadow = ((Mem & mask) >> scale) + offset
static cl::opt<int> ClMappingScale("memprof-mapping-scale",
cl::desc("scale of memprof shadow mapping"),
cl::Hidden, cl::init(DefaultShadowScale));
static cl::opt<int>
ClMappingGranularity("memprof-mapping-granularity",
cl::desc("granularity of memprof shadow mapping"),
cl::Hidden, cl::init(DefaultMemGranularity));
static cl::opt<bool> ClStack("memprof-instrument-stack",
cl::desc("Instrument scalar stack variables"),
cl::Hidden, cl::init(false));
// Debug flags.
static cl::opt<int> ClDebug("memprof-debug", cl::desc("debug"), cl::Hidden,
cl::init(0));
static cl::opt<std::string> ClDebugFunc("memprof-debug-func", cl::Hidden,
cl::desc("Debug func"));
static cl::opt<int> ClDebugMin("memprof-debug-min", cl::desc("Debug min inst"),
cl::Hidden, cl::init(-1));
static cl::opt<int> ClDebugMax("memprof-debug-max", cl::desc("Debug max inst"),
cl::Hidden, cl::init(-1));
// By default disable matching of allocation profiles onto operator new that
// already explicitly pass a hot/cold hint, since we don't currently
// override these hints anyway.
static cl::opt<bool> ClMemProfMatchHotColdNew(
"memprof-match-hot-cold-new",
cl::desc(
"Match allocation profiles onto existing hot/cold operator new calls"),
cl::Hidden, cl::init(false));
static cl::opt<bool> ClHistogram("memprof-histogram",
cl::desc("Collect access count histograms"),
cl::Hidden, cl::init(false));
static cl::opt<bool>
ClPrintMemProfMatchInfo("memprof-print-match-info",
cl::desc("Print matching stats for each allocation "
"context in this module's profiles"),
cl::Hidden, cl::init(false));
extern cl::opt<bool> MemProfReportHintedSizes;
// Instrumentation statistics
STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
STATISTIC(NumSkippedStackReads, "Number of non-instrumented stack reads");
STATISTIC(NumSkippedStackWrites, "Number of non-instrumented stack writes");
// Matching statistics
STATISTIC(NumOfMemProfMissing, "Number of functions without memory profile.");
STATISTIC(NumOfMemProfMismatch,
"Number of functions having mismatched memory profile hash.");
STATISTIC(NumOfMemProfFunc, "Number of functions having valid memory profile.");
STATISTIC(NumOfMemProfAllocContextProfiles,
"Number of alloc contexts in memory profile.");
STATISTIC(NumOfMemProfCallSiteProfiles,
"Number of callsites in memory profile.");
STATISTIC(NumOfMemProfMatchedAllocContexts,
"Number of matched memory profile alloc contexts.");
STATISTIC(NumOfMemProfMatchedAllocs,
"Number of matched memory profile allocs.");
STATISTIC(NumOfMemProfMatchedCallSites,
"Number of matched memory profile callsites.");
namespace {
/// This struct defines the shadow mapping using the rule:
/// shadow = ((mem & mask) >> Scale) ADD DynamicShadowOffset.
struct ShadowMapping {
ShadowMapping() {
Scale = ClMappingScale;
Granularity = ClHistogram ? HistogramGranularity : ClMappingGranularity;
Mask = ~(Granularity - 1);
}
int Scale;
int Granularity;
uint64_t Mask; // Computed as ~(Granularity-1)
};
static uint64_t getCtorAndDtorPriority(Triple &TargetTriple) {
return TargetTriple.isOSEmscripten() ? MemProfEmscriptenCtorAndDtorPriority
: MemProfCtorAndDtorPriority;
}
struct InterestingMemoryAccess {
Value *Addr = nullptr;
bool IsWrite;
Type *AccessTy;
Value *MaybeMask = nullptr;
};
/// Instrument the code in module to profile memory accesses.
class MemProfiler {
public:
MemProfiler(Module &M) {
C = &(M.getContext());
LongSize = M.getDataLayout().getPointerSizeInBits();
IntptrTy = Type::getIntNTy(*C, LongSize);
PtrTy = PointerType::getUnqual(*C);
}
/// If it is an interesting memory access, populate information
/// about the access and return a InterestingMemoryAccess struct.
/// Otherwise return std::nullopt.
std::optional<InterestingMemoryAccess>
isInterestingMemoryAccess(Instruction *I) const;
void instrumentMop(Instruction *I, const DataLayout &DL,
InterestingMemoryAccess &Access);
void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
Value *Addr, bool IsWrite);
void instrumentMaskedLoadOrStore(const DataLayout &DL, Value *Mask,
Instruction *I, Value *Addr, Type *AccessTy,
bool IsWrite);
void instrumentMemIntrinsic(MemIntrinsic *MI);
Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
bool instrumentFunction(Function &F);
bool maybeInsertMemProfInitAtFunctionEntry(Function &F);
bool insertDynamicShadowAtFunctionEntry(Function &F);
private:
void initializeCallbacks(Module &M);
LLVMContext *C;
int LongSize;
Type *IntptrTy;
PointerType *PtrTy;
ShadowMapping Mapping;
// These arrays is indexed by AccessIsWrite
FunctionCallee MemProfMemoryAccessCallback[2];
FunctionCallee MemProfMemmove, MemProfMemcpy, MemProfMemset;
Value *DynamicShadowOffset = nullptr;
};
class ModuleMemProfiler {
public:
ModuleMemProfiler(Module &M) { TargetTriple = Triple(M.getTargetTriple()); }
bool instrumentModule(Module &);
private:
Triple TargetTriple;
ShadowMapping Mapping;
Function *MemProfCtorFunction = nullptr;
};
} // end anonymous namespace
MemProfilerPass::MemProfilerPass() = default;
PreservedAnalyses MemProfilerPass::run(Function &F,
AnalysisManager<Function> &AM) {
assert((!ClHistogram || ClMappingGranularity == DefaultMemGranularity) &&
"Memprof with histogram only supports default mapping granularity");
Module &M = *F.getParent();
MemProfiler Profiler(M);
if (Profiler.instrumentFunction(F))
return PreservedAnalyses::none();
return PreservedAnalyses::all();
}
ModuleMemProfilerPass::ModuleMemProfilerPass() = default;
PreservedAnalyses ModuleMemProfilerPass::run(Module &M,
AnalysisManager<Module> &AM) {
ModuleMemProfiler Profiler(M);
if (Profiler.instrumentModule(M))
return PreservedAnalyses::none();
return PreservedAnalyses::all();
}
Value *MemProfiler::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
// (Shadow & mask) >> scale
Shadow = IRB.CreateAnd(Shadow, Mapping.Mask);
Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
// (Shadow >> scale) | offset
assert(DynamicShadowOffset);
return IRB.CreateAdd(Shadow, DynamicShadowOffset);
}
// Instrument memset/memmove/memcpy
void MemProfiler::instrumentMemIntrinsic(MemIntrinsic *MI) {
IRBuilder<> IRB(MI);
if (isa<MemTransferInst>(MI)) {
IRB.CreateCall(isa<MemMoveInst>(MI) ? MemProfMemmove : MemProfMemcpy,
{MI->getOperand(0), MI->getOperand(1),
IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
} else if (isa<MemSetInst>(MI)) {
IRB.CreateCall(
MemProfMemset,
{MI->getOperand(0),
IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
}
MI->eraseFromParent();
}
std::optional<InterestingMemoryAccess>
MemProfiler::isInterestingMemoryAccess(Instruction *I) const {
// Do not instrument the load fetching the dynamic shadow address.
if (DynamicShadowOffset == I)
return std::nullopt;
InterestingMemoryAccess Access;
if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
if (!ClInstrumentReads)
return std::nullopt;
Access.IsWrite = false;
Access.AccessTy = LI->getType();
Access.Addr = LI->getPointerOperand();
} else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
if (!ClInstrumentWrites)
return std::nullopt;
Access.IsWrite = true;
Access.AccessTy = SI->getValueOperand()->getType();
Access.Addr = SI->getPointerOperand();
} else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
if (!ClInstrumentAtomics)
return std::nullopt;
Access.IsWrite = true;
Access.AccessTy = RMW->getValOperand()->getType();
Access.Addr = RMW->getPointerOperand();
} else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
if (!ClInstrumentAtomics)
return std::nullopt;
Access.IsWrite = true;
Access.AccessTy = XCHG->getCompareOperand()->getType();
Access.Addr = XCHG->getPointerOperand();
} else if (auto *CI = dyn_cast<CallInst>(I)) {
auto *F = CI->getCalledFunction();
if (F && (F->getIntrinsicID() == Intrinsic::masked_load ||
F->getIntrinsicID() == Intrinsic::masked_store)) {
unsigned OpOffset = 0;
if (F->getIntrinsicID() == Intrinsic::masked_store) {
if (!ClInstrumentWrites)
return std::nullopt;
// Masked store has an initial operand for the value.
OpOffset = 1;
Access.AccessTy = CI->getArgOperand(0)->getType();
Access.IsWrite = true;
} else {
if (!ClInstrumentReads)
return std::nullopt;
Access.AccessTy = CI->getType();
Access.IsWrite = false;
}
auto *BasePtr = CI->getOperand(0 + OpOffset);
Access.MaybeMask = CI->getOperand(2 + OpOffset);
Access.Addr = BasePtr;
}
}
if (!Access.Addr)
return std::nullopt;
// Do not instrument accesses from different address spaces; we cannot deal
// with them.
Type *PtrTy = cast<PointerType>(Access.Addr->getType()->getScalarType());
if (PtrTy->getPointerAddressSpace() != 0)
return std::nullopt;
// Ignore swifterror addresses.
// swifterror memory addresses are mem2reg promoted by instruction
// selection. As such they cannot have regular uses like an instrumentation
// function and it makes no sense to track them as memory.
if (Access.Addr->isSwiftError())
return std::nullopt;
// Peel off GEPs and BitCasts.
auto *Addr = Access.Addr->stripInBoundsOffsets();
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(Addr)) {
// Do not instrument PGO counter updates.
if (GV->hasSection()) {
StringRef SectionName = GV->getSection();
// Check if the global is in the PGO counters section.
auto OF = Triple(I->getModule()->getTargetTriple()).getObjectFormat();
if (SectionName.ends_with(
getInstrProfSectionName(IPSK_cnts, OF, /*AddSegmentInfo=*/false)))
return std::nullopt;
}
// Do not instrument accesses to LLVM internal variables.
if (GV->getName().starts_with("__llvm"))
return std::nullopt;
}
return Access;
}
void MemProfiler::instrumentMaskedLoadOrStore(const DataLayout &DL, Value *Mask,
Instruction *I, Value *Addr,
Type *AccessTy, bool IsWrite) {
auto *VTy = cast<FixedVectorType>(AccessTy);
unsigned Num = VTy->getNumElements();
auto *Zero = ConstantInt::get(IntptrTy, 0);
for (unsigned Idx = 0; Idx < Num; ++Idx) {
Value *InstrumentedAddress = nullptr;
Instruction *InsertBefore = I;
if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
// dyn_cast as we might get UndefValue
if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
if (Masked->isZero())
// Mask is constant false, so no instrumentation needed.
continue;
// If we have a true or undef value, fall through to instrumentAddress.
// with InsertBefore == I
}
} else {
IRBuilder<> IRB(I);
Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
Instruction *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
InsertBefore = ThenTerm;
}
IRBuilder<> IRB(InsertBefore);
InstrumentedAddress =
IRB.CreateGEP(VTy, Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
instrumentAddress(I, InsertBefore, InstrumentedAddress, IsWrite);
}
}
void MemProfiler::instrumentMop(Instruction *I, const DataLayout &DL,
InterestingMemoryAccess &Access) {
// Skip instrumentation of stack accesses unless requested.
if (!ClStack && isa<AllocaInst>(getUnderlyingObject(Access.Addr))) {
if (Access.IsWrite)
++NumSkippedStackWrites;
else
++NumSkippedStackReads;
return;
}
if (Access.IsWrite)
NumInstrumentedWrites++;
else
NumInstrumentedReads++;
if (Access.MaybeMask) {
instrumentMaskedLoadOrStore(DL, Access.MaybeMask, I, Access.Addr,
Access.AccessTy, Access.IsWrite);
} else {
// Since the access counts will be accumulated across the entire allocation,
// we only update the shadow access count for the first location and thus
// don't need to worry about alignment and type size.
instrumentAddress(I, I, Access.Addr, Access.IsWrite);
}
}
void MemProfiler::instrumentAddress(Instruction *OrigIns,
Instruction *InsertBefore, Value *Addr,
bool IsWrite) {
IRBuilder<> IRB(InsertBefore);
Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
if (ClUseCalls) {
IRB.CreateCall(MemProfMemoryAccessCallback[IsWrite], AddrLong);
return;
}
Type *ShadowTy = ClHistogram ? Type::getInt8Ty(*C) : Type::getInt64Ty(*C);
Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
Value *ShadowPtr = memToShadow(AddrLong, IRB);
Value *ShadowAddr = IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy);
Value *ShadowValue = IRB.CreateLoad(ShadowTy, ShadowAddr);
// If we are profiling with histograms, add overflow protection at 255.
if (ClHistogram) {
Value *MaxCount = ConstantInt::get(Type::getInt8Ty(*C), 255);
Value *Cmp = IRB.CreateICmpULT(ShadowValue, MaxCount);
Instruction *IncBlock =
SplitBlockAndInsertIfThen(Cmp, InsertBefore, /*Unreachable=*/false);
IRB.SetInsertPoint(IncBlock);
}
Value *Inc = ConstantInt::get(ShadowTy, 1);
ShadowValue = IRB.CreateAdd(ShadowValue, Inc);
IRB.CreateStore(ShadowValue, ShadowAddr);
}
// Create the variable for the profile file name.
void createProfileFileNameVar(Module &M) {
const MDString *MemProfFilename =
dyn_cast_or_null<MDString>(M.getModuleFlag("MemProfProfileFilename"));
if (!MemProfFilename)
return;
assert(!MemProfFilename->getString().empty() &&
"Unexpected MemProfProfileFilename metadata with empty string");
Constant *ProfileNameConst = ConstantDataArray::getString(
M.getContext(), MemProfFilename->getString(), true);
GlobalVariable *ProfileNameVar = new GlobalVariable(
M, ProfileNameConst->getType(), /*isConstant=*/true,
GlobalValue::WeakAnyLinkage, ProfileNameConst, MemProfFilenameVar);
Triple TT(M.getTargetTriple());
if (TT.supportsCOMDAT()) {
ProfileNameVar->setLinkage(GlobalValue::ExternalLinkage);
ProfileNameVar->setComdat(M.getOrInsertComdat(MemProfFilenameVar));
}
}
// Set MemprofHistogramFlag as a Global veriable in IR. This makes it accessible
// to the runtime, changing shadow count behavior.
void createMemprofHistogramFlagVar(Module &M) {
const StringRef VarName(MemProfHistogramFlagVar);
Type *IntTy1 = Type::getInt1Ty(M.getContext());
auto MemprofHistogramFlag = new GlobalVariable(
M, IntTy1, true, GlobalValue::WeakAnyLinkage,
Constant::getIntegerValue(IntTy1, APInt(1, ClHistogram)), VarName);
Triple TT(M.getTargetTriple());
if (TT.supportsCOMDAT()) {
MemprofHistogramFlag->setLinkage(GlobalValue::ExternalLinkage);
MemprofHistogramFlag->setComdat(M.getOrInsertComdat(VarName));
}
appendToCompilerUsed(M, MemprofHistogramFlag);
}
bool ModuleMemProfiler::instrumentModule(Module &M) {
// Create a module constructor.
std::string MemProfVersion = std::to_string(LLVM_MEM_PROFILER_VERSION);
std::string VersionCheckName =
ClInsertVersionCheck ? (MemProfVersionCheckNamePrefix + MemProfVersion)
: "";
std::tie(MemProfCtorFunction, std::ignore) =
createSanitizerCtorAndInitFunctions(M, MemProfModuleCtorName,
MemProfInitName, /*InitArgTypes=*/{},
/*InitArgs=*/{}, VersionCheckName);
const uint64_t Priority = getCtorAndDtorPriority(TargetTriple);
appendToGlobalCtors(M, MemProfCtorFunction, Priority);
createProfileFileNameVar(M);
createMemprofHistogramFlagVar(M);
return true;
}
void MemProfiler::initializeCallbacks(Module &M) {
IRBuilder<> IRB(*C);
for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
const std::string TypeStr = AccessIsWrite ? "store" : "load";
const std::string HistPrefix = ClHistogram ? "hist_" : "";
SmallVector<Type *, 2> Args1{1, IntptrTy};
MemProfMemoryAccessCallback[AccessIsWrite] = M.getOrInsertFunction(
ClMemoryAccessCallbackPrefix + HistPrefix + TypeStr,
FunctionType::get(IRB.getVoidTy(), Args1, false));
}
MemProfMemmove = M.getOrInsertFunction(
ClMemoryAccessCallbackPrefix + "memmove", PtrTy, PtrTy, PtrTy, IntptrTy);
MemProfMemcpy = M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "memcpy",
PtrTy, PtrTy, PtrTy, IntptrTy);
MemProfMemset =
M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "memset", PtrTy,
PtrTy, IRB.getInt32Ty(), IntptrTy);
}
bool MemProfiler::maybeInsertMemProfInitAtFunctionEntry(Function &F) {
// For each NSObject descendant having a +load method, this method is invoked
// by the ObjC runtime before any of the static constructors is called.
// Therefore we need to instrument such methods with a call to __memprof_init
// at the beginning in order to initialize our runtime before any access to
// the shadow memory.
// We cannot just ignore these methods, because they may call other
// instrumented functions.
if (F.getName().contains(" load]")) {
FunctionCallee MemProfInitFunction =
declareSanitizerInitFunction(*F.getParent(), MemProfInitName, {});
IRBuilder<> IRB(&F.front(), F.front().begin());
IRB.CreateCall(MemProfInitFunction, {});
return true;
}
return false;
}
bool MemProfiler::insertDynamicShadowAtFunctionEntry(Function &F) {
IRBuilder<> IRB(&F.front().front());
Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
MemProfShadowMemoryDynamicAddress, IntptrTy);
if (F.getParent()->getPICLevel() == PICLevel::NotPIC)
cast<GlobalVariable>(GlobalDynamicAddress)->setDSOLocal(true);
DynamicShadowOffset = IRB.CreateLoad(IntptrTy, GlobalDynamicAddress);
return true;
}
bool MemProfiler::instrumentFunction(Function &F) {
if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage)
return false;
if (ClDebugFunc == F.getName())
return false;
if (F.getName().starts_with("__memprof_"))
return false;
bool FunctionModified = false;
// If needed, insert __memprof_init.
// This function needs to be called even if the function body is not
// instrumented.
if (maybeInsertMemProfInitAtFunctionEntry(F))
FunctionModified = true;
LLVM_DEBUG(dbgs() << "MEMPROF instrumenting:\n" << F << "\n");
initializeCallbacks(*F.getParent());
SmallVector<Instruction *, 16> ToInstrument;
// Fill the set of memory operations to instrument.
for (auto &BB : F) {
for (auto &Inst : BB) {
if (isInterestingMemoryAccess(&Inst) || isa<MemIntrinsic>(Inst))
ToInstrument.push_back(&Inst);
}
}
if (ToInstrument.empty()) {
LLVM_DEBUG(dbgs() << "MEMPROF done instrumenting: " << FunctionModified
<< " " << F << "\n");
return FunctionModified;
}
FunctionModified |= insertDynamicShadowAtFunctionEntry(F);
int NumInstrumented = 0;
for (auto *Inst : ToInstrument) {
if (ClDebugMin < 0 || ClDebugMax < 0 ||
(NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
std::optional<InterestingMemoryAccess> Access =
isInterestingMemoryAccess(Inst);
if (Access)
instrumentMop(Inst, F.getDataLayout(), *Access);
else
instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
}
NumInstrumented++;
}
if (NumInstrumented > 0)
FunctionModified = true;
LLVM_DEBUG(dbgs() << "MEMPROF done instrumenting: " << FunctionModified << " "
<< F << "\n");
return FunctionModified;
}
static void addCallsiteMetadata(Instruction &I,
ArrayRef<uint64_t> InlinedCallStack,
LLVMContext &Ctx) {
I.setMetadata(LLVMContext::MD_callsite,
buildCallstackMetadata(InlinedCallStack, Ctx));
}
static uint64_t computeStackId(GlobalValue::GUID Function, uint32_t LineOffset,
uint32_t Column) {
llvm::HashBuilder<llvm::TruncatedBLAKE3<8>, llvm::endianness::little>
HashBuilder;
HashBuilder.add(Function, LineOffset, Column);
llvm::BLAKE3Result<8> Hash = HashBuilder.final();
uint64_t Id;
std::memcpy(&Id, Hash.data(), sizeof(Hash));
return Id;
}
static uint64_t computeStackId(const memprof::Frame &Frame) {
return computeStackId(Frame.Function, Frame.LineOffset, Frame.Column);
}
// Helper to generate a single hash id for a given callstack, used for emitting
// matching statistics and useful for uniquing such statistics across modules.
static uint64_t
computeFullStackId(const std::vector<memprof::Frame> &CallStack) {
llvm::HashBuilder<llvm::TruncatedBLAKE3<8>, llvm::endianness::little>
HashBuilder;
for (auto &F : CallStack)
HashBuilder.add(F.Function, F.LineOffset, F.Column);
llvm::BLAKE3Result<8> Hash = HashBuilder.final();
uint64_t Id;
std::memcpy(&Id, Hash.data(), sizeof(Hash));
return Id;
}
static AllocationType addCallStack(CallStackTrie &AllocTrie,
const AllocationInfo *AllocInfo,
uint64_t FullStackId) {
SmallVector<uint64_t> StackIds;
for (const auto &StackFrame : AllocInfo->CallStack)
StackIds.push_back(computeStackId(StackFrame));
auto AllocType = getAllocType(AllocInfo->Info.getTotalLifetimeAccessDensity(),
AllocInfo->Info.getAllocCount(),
AllocInfo->Info.getTotalLifetime());
std::vector<ContextTotalSize> ContextSizeInfo;
if (MemProfReportHintedSizes) {
auto TotalSize = AllocInfo->Info.getTotalSize();
assert(TotalSize);
assert(FullStackId != 0);
ContextSizeInfo.push_back({FullStackId, TotalSize});
}
AllocTrie.addCallStack(AllocType, StackIds, std::move(ContextSizeInfo));
return AllocType;
}
// Helper to compare the InlinedCallStack computed from an instruction's debug
// info to a list of Frames from profile data (either the allocation data or a
// callsite). For callsites, the StartIndex to use in the Frame array may be
// non-zero.
static bool
stackFrameIncludesInlinedCallStack(ArrayRef<Frame> ProfileCallStack,
ArrayRef<uint64_t> InlinedCallStack,
unsigned StartIndex = 0) {
auto StackFrame = ProfileCallStack.begin() + StartIndex;
auto InlCallStackIter = InlinedCallStack.begin();
for (; StackFrame != ProfileCallStack.end() &&
InlCallStackIter != InlinedCallStack.end();
++StackFrame, ++InlCallStackIter) {
uint64_t StackId = computeStackId(*StackFrame);
if (StackId != *InlCallStackIter)
return false;
}
// Return true if we found and matched all stack ids from the call
// instruction.
return InlCallStackIter == InlinedCallStack.end();
}
static bool isAllocationWithHotColdVariant(const Function *Callee,
const TargetLibraryInfo &TLI) {
if (!Callee)
return false;
LibFunc Func;
if (!TLI.getLibFunc(*Callee, Func))
return false;
switch (Func) {
case LibFunc_Znwm:
case LibFunc_ZnwmRKSt9nothrow_t:
case LibFunc_ZnwmSt11align_val_t:
case LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t:
case LibFunc_Znam:
case LibFunc_ZnamRKSt9nothrow_t:
case LibFunc_ZnamSt11align_val_t:
case LibFunc_ZnamSt11align_val_tRKSt9nothrow_t:
case LibFunc_size_returning_new:
case LibFunc_size_returning_new_aligned:
return true;
case LibFunc_Znwm12__hot_cold_t:
case LibFunc_ZnwmRKSt9nothrow_t12__hot_cold_t:
case LibFunc_ZnwmSt11align_val_t12__hot_cold_t:
case LibFunc_ZnwmSt11align_val_tRKSt9nothrow_t12__hot_cold_t:
case LibFunc_Znam12__hot_cold_t:
case LibFunc_ZnamRKSt9nothrow_t12__hot_cold_t:
case LibFunc_ZnamSt11align_val_t12__hot_cold_t:
case LibFunc_ZnamSt11align_val_tRKSt9nothrow_t12__hot_cold_t:
case LibFunc_size_returning_new_hot_cold:
case LibFunc_size_returning_new_aligned_hot_cold:
return ClMemProfMatchHotColdNew;
default:
return false;
}
}
struct AllocMatchInfo {
uint64_t TotalSize = 0;
AllocationType AllocType = AllocationType::None;
bool Matched = false;
};
DenseMap<uint64_t, SmallVector<CallEdgeTy, 0>>
memprof::extractCallsFromIR(Module &M, const TargetLibraryInfo &TLI) {
DenseMap<uint64_t, SmallVector<CallEdgeTy, 0>> Calls;
auto GetOffset = [](const DILocation *DIL) {
return (DIL->getLine() - DIL->getScope()->getSubprogram()->getLine()) &
0xffff;
};
for (Function &F : M) {
if (F.isDeclaration())
continue;
for (auto &BB : F) {
for (auto &I : BB) {
if (!isa<CallBase>(&I) || isa<IntrinsicInst>(&I))
continue;
auto *CB = dyn_cast<CallBase>(&I);
auto *CalledFunction = CB->getCalledFunction();
// Disregard indirect calls and intrinsics.
if (!CalledFunction || CalledFunction->isIntrinsic())
continue;
StringRef CalleeName = CalledFunction->getName();
bool IsAlloc = isAllocationWithHotColdVariant(CalledFunction, TLI);
for (const DILocation *DIL = I.getDebugLoc(); DIL;
DIL = DIL->getInlinedAt()) {
StringRef CallerName = DIL->getSubprogramLinkageName();
assert(!CallerName.empty() &&
"Be sure to enable -fdebug-info-for-profiling");
uint64_t CallerGUID = IndexedMemProfRecord::getGUID(CallerName);
uint64_t CalleeGUID = IndexedMemProfRecord::getGUID(CalleeName);
// Pretend that we are calling a function with GUID == 0 if we are
// calling a heap allocation function.
if (IsAlloc)
CalleeGUID = 0;
LineLocation Loc = {GetOffset(DIL), DIL->getColumn()};
Calls[CallerGUID].emplace_back(Loc, CalleeGUID);
CalleeName = CallerName;
// FIXME: Recognize other frames that are associated with heap
// allocation functions. It may be too early to reset IsAlloc to
// false here.
IsAlloc = false;
}
}
}
}
// Sort each call list by the source location.
for (auto &[CallerGUID, CallList] : Calls) {
llvm::sort(CallList);
CallList.erase(llvm::unique(CallList), CallList.end());
}
return Calls;
}
DenseMap<uint64_t, LocToLocMap>
memprof::computeUndriftMap(Module &M, IndexedInstrProfReader *MemProfReader,
const TargetLibraryInfo &TLI) {
DenseMap<uint64_t, LocToLocMap> UndriftMaps;
DenseMap<uint64_t, SmallVector<memprof::CallEdgeTy, 0>> CallsFromProfile =
MemProfReader->getMemProfCallerCalleePairs();
DenseMap<uint64_t, SmallVector<memprof::CallEdgeTy, 0>> CallsFromIR =
extractCallsFromIR(M, TLI);
// Compute an undrift map for each CallerGUID.
for (const auto &[CallerGUID, IRAnchors] : CallsFromIR) {
auto It = CallsFromProfile.find(CallerGUID);
if (It == CallsFromProfile.end())
continue;
const auto &ProfileAnchors = It->second;
LocToLocMap Matchings;
longestCommonSequence<LineLocation, GlobalValue::GUID>(
ProfileAnchors, IRAnchors, std::equal_to<GlobalValue::GUID>(),
[&](LineLocation A, LineLocation B) { Matchings.try_emplace(A, B); });
bool Inserted = UndriftMaps.try_emplace(CallerGUID, Matchings).second;
// The insertion must succeed because we visit each GUID exactly once.
assert(Inserted);
(void)Inserted;
}
return UndriftMaps;
}
static void
readMemprof(Module &M, Function &F, IndexedInstrProfReader *MemProfReader,
const TargetLibraryInfo &TLI,
std::map<uint64_t, AllocMatchInfo> &FullStackIdToAllocMatchInfo) {
auto &Ctx = M.getContext();
// Previously we used getIRPGOFuncName() here. If F is local linkage,
// getIRPGOFuncName() returns FuncName with prefix 'FileName;'. But
// llvm-profdata uses FuncName in dwarf to create GUID which doesn't
// contain FileName's prefix. It caused local linkage function can't
// find MemProfRecord. So we use getName() now.
// 'unique-internal-linkage-names' can make MemProf work better for local
// linkage function.
auto FuncName = F.getName();
auto FuncGUID = Function::getGUID(FuncName);
std::optional<memprof::MemProfRecord> MemProfRec;
auto Err = MemProfReader->getMemProfRecord(FuncGUID).moveInto(MemProfRec);
if (Err) {
handleAllErrors(std::move(Err), [&](const InstrProfError &IPE) {
auto Err = IPE.get();
bool SkipWarning = false;
LLVM_DEBUG(dbgs() << "Error in reading profile for Func " << FuncName
<< ": ");
if (Err == instrprof_error::unknown_function) {
NumOfMemProfMissing++;
SkipWarning = !PGOWarnMissing;
LLVM_DEBUG(dbgs() << "unknown function");
} else if (Err == instrprof_error::hash_mismatch) {
NumOfMemProfMismatch++;
SkipWarning =
NoPGOWarnMismatch ||
(NoPGOWarnMismatchComdatWeak &&
(F.hasComdat() ||
F.getLinkage() == GlobalValue::AvailableExternallyLinkage));
LLVM_DEBUG(dbgs() << "hash mismatch (skip=" << SkipWarning << ")");
}
if (SkipWarning)
return;
std::string Msg = (IPE.message() + Twine(" ") + F.getName().str() +
Twine(" Hash = ") + std::to_string(FuncGUID))
.str();
Ctx.diagnose(
DiagnosticInfoPGOProfile(M.getName().data(), Msg, DS_Warning));
});
return;
}
NumOfMemProfFunc++;
// Detect if there are non-zero column numbers in the profile. If not,
// treat all column numbers as 0 when matching (i.e. ignore any non-zero
// columns in the IR). The profiled binary might have been built with
// column numbers disabled, for example.
bool ProfileHasColumns = false;
// Build maps of the location hash to all profile data with that leaf location
// (allocation info and the callsites).
std::map<uint64_t, std::set<const AllocationInfo *>> LocHashToAllocInfo;
// For the callsites we need to record the index of the associated frame in
// the frame array (see comments below where the map entries are added).
std::map<uint64_t, std::set<std::pair<const std::vector<Frame> *, unsigned>>>
LocHashToCallSites;
for (auto &AI : MemProfRec->AllocSites) {
NumOfMemProfAllocContextProfiles++;
// Associate the allocation info with the leaf frame. The later matching
// code will match any inlined call sequences in the IR with a longer prefix
// of call stack frames.
uint64_t StackId = computeStackId(AI.CallStack[0]);
LocHashToAllocInfo[StackId].insert(&AI);
ProfileHasColumns |= AI.CallStack[0].Column;
}
for (auto &CS : MemProfRec->CallSites) {
NumOfMemProfCallSiteProfiles++;
// Need to record all frames from leaf up to and including this function,
// as any of these may or may not have been inlined at this point.
unsigned Idx = 0;
for (auto &StackFrame : CS) {
uint64_t StackId = computeStackId(StackFrame);
LocHashToCallSites[StackId].insert(std::make_pair(&CS, Idx++));
ProfileHasColumns |= StackFrame.Column;
// Once we find this function, we can stop recording.
if (StackFrame.Function == FuncGUID)
break;
}
assert(Idx <= CS.size() && CS[Idx - 1].Function == FuncGUID);
}
auto GetOffset = [](const DILocation *DIL) {
return (DIL->getLine() - DIL->getScope()->getSubprogram()->getLine()) &
0xffff;
};
// Now walk the instructions, looking up the associated profile data using
// debug locations.
for (auto &BB : F) {
for (auto &I : BB) {
if (I.isDebugOrPseudoInst())
continue;
// We are only interested in calls (allocation or interior call stack
// context calls).
auto *CI = dyn_cast<CallBase>(&I);
if (!CI)
continue;
auto *CalledFunction = CI->getCalledFunction();
if (CalledFunction && CalledFunction->isIntrinsic())
continue;
// List of call stack ids computed from the location hashes on debug
// locations (leaf to inlined at root).
SmallVector<uint64_t, 8> InlinedCallStack;
// Was the leaf location found in one of the profile maps?
bool LeafFound = false;
// If leaf was found in a map, iterators pointing to its location in both
// of the maps. It might exist in neither, one, or both (the latter case
// can happen because we don't currently have discriminators to
// distinguish the case when a single line/col maps to both an allocation
// and another callsite).
std::map<uint64_t, std::set<const AllocationInfo *>>::iterator
AllocInfoIter;
std::map<uint64_t, std::set<std::pair<const std::vector<Frame> *,
unsigned>>>::iterator CallSitesIter;
for (const DILocation *DIL = I.getDebugLoc(); DIL != nullptr;
DIL = DIL->getInlinedAt()) {
// Use C++ linkage name if possible. Need to compile with
// -fdebug-info-for-profiling to get linkage name.
StringRef Name = DIL->getScope()->getSubprogram()->getLinkageName();
if (Name.empty())
Name = DIL->getScope()->getSubprogram()->getName();
auto CalleeGUID = Function::getGUID(Name);
auto StackId = computeStackId(CalleeGUID, GetOffset(DIL),
ProfileHasColumns ? DIL->getColumn() : 0);
// Check if we have found the profile's leaf frame. If yes, collect
// the rest of the call's inlined context starting here. If not, see if
// we find a match further up the inlined context (in case the profile
// was missing debug frames at the leaf).
if (!LeafFound) {
AllocInfoIter = LocHashToAllocInfo.find(StackId);
CallSitesIter = LocHashToCallSites.find(StackId);
if (AllocInfoIter != LocHashToAllocInfo.end() ||
CallSitesIter != LocHashToCallSites.end())
LeafFound = true;
}
if (LeafFound)
InlinedCallStack.push_back(StackId);
}
// If leaf not in either of the maps, skip inst.
if (!LeafFound)
continue;
// First add !memprof metadata from allocation info, if we found the
// instruction's leaf location in that map, and if the rest of the
// instruction's locations match the prefix Frame locations on an
// allocation context with the same leaf.
if (AllocInfoIter != LocHashToAllocInfo.end()) {
// Only consider allocations which support hinting.
if (!isAllocationWithHotColdVariant(CI->getCalledFunction(), TLI))
continue;
// We may match this instruction's location list to multiple MIB
// contexts. Add them to a Trie specialized for trimming the contexts to
// the minimal needed to disambiguate contexts with unique behavior.
CallStackTrie AllocTrie;
for (auto *AllocInfo : AllocInfoIter->second) {
// Check the full inlined call stack against this one.
// If we found and thus matched all frames on the call, include
// this MIB.
if (stackFrameIncludesInlinedCallStack(AllocInfo->CallStack,
InlinedCallStack)) {
NumOfMemProfMatchedAllocContexts++;
uint64_t FullStackId = 0;
if (ClPrintMemProfMatchInfo || MemProfReportHintedSizes)
FullStackId = computeFullStackId(AllocInfo->CallStack);
auto AllocType = addCallStack(AllocTrie, AllocInfo, FullStackId);
// Record information about the allocation if match info printing
// was requested.
if (ClPrintMemProfMatchInfo) {
assert(FullStackId != 0);
FullStackIdToAllocMatchInfo[FullStackId] = {
AllocInfo->Info.getTotalSize(), AllocType, /*Matched=*/true};
}
}
}
// We might not have matched any to the full inlined call stack.
// But if we did, create and attach metadata, or a function attribute if
// all contexts have identical profiled behavior.
if (!AllocTrie.empty()) {
NumOfMemProfMatchedAllocs++;
// MemprofMDAttached will be false if a function attribute was
// attached.
bool MemprofMDAttached = AllocTrie.buildAndAttachMIBMetadata(CI);
assert(MemprofMDAttached == I.hasMetadata(LLVMContext::MD_memprof));
if (MemprofMDAttached) {
// Add callsite metadata for the instruction's location list so that
// it simpler later on to identify which part of the MIB contexts
// are from this particular instruction (including during inlining,
// when the callsite metadata will be updated appropriately).
// FIXME: can this be changed to strip out the matching stack
// context ids from the MIB contexts and not add any callsite
// metadata here to save space?
addCallsiteMetadata(I, InlinedCallStack, Ctx);
}
}
continue;
}
// Otherwise, add callsite metadata. If we reach here then we found the
// instruction's leaf location in the callsites map and not the allocation
// map.
assert(CallSitesIter != LocHashToCallSites.end());
for (auto CallStackIdx : CallSitesIter->second) {
// If we found and thus matched all frames on the call, create and
// attach call stack metadata.
if (stackFrameIncludesInlinedCallStack(
*CallStackIdx.first, InlinedCallStack, CallStackIdx.second)) {
NumOfMemProfMatchedCallSites++;
addCallsiteMetadata(I, InlinedCallStack, Ctx);
// Only need to find one with a matching call stack and add a single
// callsite metadata.
break;
}
}
}
}
}
MemProfUsePass::MemProfUsePass(std::string MemoryProfileFile,
IntrusiveRefCntPtr<vfs::FileSystem> FS)
: MemoryProfileFileName(MemoryProfileFile), FS(FS) {
if (!FS)
this->FS = vfs::getRealFileSystem();
}
PreservedAnalyses MemProfUsePass::run(Module &M, ModuleAnalysisManager &AM) {
// Return immediately if the module doesn't contain any function.
if (M.empty())
return PreservedAnalyses::all();
LLVM_DEBUG(dbgs() << "Read in memory profile:");
auto &Ctx = M.getContext();
auto ReaderOrErr = IndexedInstrProfReader::create(MemoryProfileFileName, *FS);
if (Error E = ReaderOrErr.takeError()) {
handleAllErrors(std::move(E), [&](const ErrorInfoBase &EI) {
Ctx.diagnose(
DiagnosticInfoPGOProfile(MemoryProfileFileName.data(), EI.message()));
});
return PreservedAnalyses::all();
}
std::unique_ptr<IndexedInstrProfReader> MemProfReader =
std::move(ReaderOrErr.get());
if (!MemProfReader) {
Ctx.diagnose(DiagnosticInfoPGOProfile(
MemoryProfileFileName.data(), StringRef("Cannot get MemProfReader")));
return PreservedAnalyses::all();
}
if (!MemProfReader->hasMemoryProfile()) {
Ctx.diagnose(DiagnosticInfoPGOProfile(MemoryProfileFileName.data(),
"Not a memory profile"));
return PreservedAnalyses::all();
}
auto &FAM = AM.getResult<FunctionAnalysisManagerModuleProxy>(M).getManager();
// Map from the stack has of each allocation context in the function profiles
// to the total profiled size (bytes), allocation type, and whether we matched
// it to an allocation in the IR.
std::map<uint64_t, AllocMatchInfo> FullStackIdToAllocMatchInfo;
for (auto &F : M) {
if (F.isDeclaration())
continue;
const TargetLibraryInfo &TLI = FAM.getResult<TargetLibraryAnalysis>(F);
readMemprof(M, F, MemProfReader.get(), TLI, FullStackIdToAllocMatchInfo);
}
if (ClPrintMemProfMatchInfo) {
for (const auto &[Id, Info] : FullStackIdToAllocMatchInfo)
errs() << "MemProf " << getAllocTypeAttributeString(Info.AllocType)
<< " context with id " << Id << " has total profiled size "
<< Info.TotalSize << (Info.Matched ? " is" : " not")
<< " matched\n";
}
return PreservedAnalyses::none();
}
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