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llvm-project/llvm/lib/ProfileData/InstrProfCorrelator.cpp

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//===-- InstrProfCorrelator.cpp -------------------------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
#include "llvm/ProfileData/InstrProfCorrelator.h"
#include "llvm/DebugInfo/DIContext.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFDie.h"
#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
#include "llvm/DebugInfo/DWARF/DWARFFormValue.h"
#include "llvm/DebugInfo/DWARF/DWARFLocationExpression.h"
#include "llvm/DebugInfo/DWARF/DWARFUnit.h"
#include "llvm/Object/MachO.h"
#include "llvm/Support/Debug.h"
#define DEBUG_TYPE "correlator"
using namespace llvm;
/// Get the __llvm_prf_cnts section.
Expected<object::SectionRef> getCountersSection(const object::ObjectFile &Obj) {
for (auto &Section : Obj.sections())
if (auto SectionName = Section.getName())
if (SectionName.get() == INSTR_PROF_CNTS_SECT_NAME)
return Section;
return make_error<InstrProfError>(
instrprof_error::unable_to_correlate_profile,
"could not find counter section (" INSTR_PROF_CNTS_SECT_NAME ")");
}
const char *InstrProfCorrelator::FunctionNameAttributeName = "Function Name";
const char *InstrProfCorrelator::CFGHashAttributeName = "CFG Hash";
const char *InstrProfCorrelator::NumCountersAttributeName = "Num Counters";
llvm::Expected<std::unique_ptr<InstrProfCorrelator::Context>>
InstrProfCorrelator::Context::get(std::unique_ptr<MemoryBuffer> Buffer,
const object::ObjectFile &Obj) {
auto CountersSection = getCountersSection(Obj);
if (auto Err = CountersSection.takeError())
return std::move(Err);
auto C = std::make_unique<Context>();
C->Buffer = std::move(Buffer);
C->CountersSectionStart = CountersSection->getAddress();
C->CountersSectionEnd = C->CountersSectionStart + CountersSection->getSize();
C->ShouldSwapBytes = Obj.isLittleEndian() != sys::IsLittleEndianHost;
return Expected<std::unique_ptr<Context>>(std::move(C));
}
llvm::Expected<std::unique_ptr<InstrProfCorrelator>>
InstrProfCorrelator::get(StringRef DebugInfoFilename) {
auto DsymObjectsOrErr =
object::MachOObjectFile::findDsymObjectMembers(DebugInfoFilename);
if (auto Err = DsymObjectsOrErr.takeError())
return std::move(Err);
if (!DsymObjectsOrErr->empty()) {
// TODO: Enable profile correlation when there are multiple objects in a
// dSYM bundle.
if (DsymObjectsOrErr->size() > 1)
return make_error<InstrProfError>(
instrprof_error::unable_to_correlate_profile,
"using multiple objects is not yet supported");
DebugInfoFilename = *DsymObjectsOrErr->begin();
}
auto BufferOrErr =
errorOrToExpected(MemoryBuffer::getFile(DebugInfoFilename));
if (auto Err = BufferOrErr.takeError())
return std::move(Err);
return get(std::move(*BufferOrErr));
}
llvm::Expected<std::unique_ptr<InstrProfCorrelator>>
InstrProfCorrelator::get(std::unique_ptr<MemoryBuffer> Buffer) {
auto BinOrErr = object::createBinary(*Buffer);
if (auto Err = BinOrErr.takeError())
return std::move(Err);
if (auto *Obj = dyn_cast<object::ObjectFile>(BinOrErr->get())) {
auto CtxOrErr = Context::get(std::move(Buffer), *Obj);
if (auto Err = CtxOrErr.takeError())
return std::move(Err);
auto T = Obj->makeTriple();
if (T.isArch64Bit())
return InstrProfCorrelatorImpl<uint64_t>::get(std::move(*CtxOrErr), *Obj);
if (T.isArch32Bit())
return InstrProfCorrelatorImpl<uint32_t>::get(std::move(*CtxOrErr), *Obj);
}
return make_error<InstrProfError>(
instrprof_error::unable_to_correlate_profile, "not an object file");
}
Optional<size_t> InstrProfCorrelator::getDataSize() const {
if (auto *C = dyn_cast<InstrProfCorrelatorImpl<uint32_t>>(this)) {
return C->getDataSize();
} else if (auto *C = dyn_cast<InstrProfCorrelatorImpl<uint64_t>>(this)) {
return C->getDataSize();
}
return {};
}
namespace llvm {
template <>
InstrProfCorrelatorImpl<uint32_t>::InstrProfCorrelatorImpl(
std::unique_ptr<InstrProfCorrelator::Context> Ctx)
: InstrProfCorrelatorImpl(InstrProfCorrelatorKind::CK_32Bit,
std::move(Ctx)) {}
template <>
InstrProfCorrelatorImpl<uint64_t>::InstrProfCorrelatorImpl(
std::unique_ptr<InstrProfCorrelator::Context> Ctx)
: InstrProfCorrelatorImpl(InstrProfCorrelatorKind::CK_64Bit,
std::move(Ctx)) {}
template <>
bool InstrProfCorrelatorImpl<uint32_t>::classof(const InstrProfCorrelator *C) {
return C->getKind() == InstrProfCorrelatorKind::CK_32Bit;
}
template <>
bool InstrProfCorrelatorImpl<uint64_t>::classof(const InstrProfCorrelator *C) {
return C->getKind() == InstrProfCorrelatorKind::CK_64Bit;
}
} // end namespace llvm
template <class IntPtrT>
llvm::Expected<std::unique_ptr<InstrProfCorrelatorImpl<IntPtrT>>>
InstrProfCorrelatorImpl<IntPtrT>::get(
std::unique_ptr<InstrProfCorrelator::Context> Ctx,
const object::ObjectFile &Obj) {
if (Obj.isELF() || Obj.isMachO()) {
auto DICtx = DWARFContext::create(Obj);
return std::make_unique<DwarfInstrProfCorrelator<IntPtrT>>(std::move(DICtx),
std::move(Ctx));
}
return make_error<InstrProfError>(
instrprof_error::unable_to_correlate_profile,
"unsupported debug info format (only DWARF is supported)");
}
template <class IntPtrT>
Error InstrProfCorrelatorImpl<IntPtrT>::correlateProfileData() {
assert(Data.empty() && Names.empty() && NamesVec.empty());
correlateProfileDataImpl();
if (Data.empty() || NamesVec.empty())
return make_error<InstrProfError>(
instrprof_error::unable_to_correlate_profile,
"could not find any profile metadata in debug info");
auto Result =
collectPGOFuncNameStrings(NamesVec, /*doCompression=*/false, Names);
CounterOffsets.clear();
NamesVec.clear();
return Result;
}
template <class IntPtrT>
void InstrProfCorrelatorImpl<IntPtrT>::addProbe(StringRef FunctionName,
uint64_t CFGHash,
IntPtrT CounterOffset,
IntPtrT FunctionPtr,
uint32_t NumCounters) {
// Check if a probe was already added for this counter offset.
if (!CounterOffsets.insert(CounterOffset).second)
return;
Data.push_back({
maybeSwap<uint64_t>(IndexedInstrProf::ComputeHash(FunctionName)),
maybeSwap<uint64_t>(CFGHash),
// In this mode, CounterPtr actually stores the section relative address
// of the counter.
maybeSwap<IntPtrT>(CounterOffset),
maybeSwap<IntPtrT>(FunctionPtr),
// TODO: Value profiling is not yet supported.
/*ValuesPtr=*/maybeSwap<IntPtrT>(0),
maybeSwap<uint32_t>(NumCounters),
/*NumValueSites=*/{maybeSwap<uint16_t>(0), maybeSwap<uint16_t>(0)},
});
NamesVec.push_back(FunctionName.str());
}
template <class IntPtrT>
llvm::Optional<uint64_t>
DwarfInstrProfCorrelator<IntPtrT>::getLocation(const DWARFDie &Die) const {
auto Locations = Die.getLocations(dwarf::DW_AT_location);
if (!Locations) {
consumeError(Locations.takeError());
return {};
}
auto &DU = *Die.getDwarfUnit();
auto AddressSize = DU.getAddressByteSize();
for (auto &Location : *Locations) {
DataExtractor Data(Location.Expr, DICtx->isLittleEndian(), AddressSize);
DWARFExpression Expr(Data, AddressSize);
for (auto &Op : Expr) {
if (Op.getCode() == dwarf::DW_OP_addr) {
return Op.getRawOperand(0);
} else if (Op.getCode() == dwarf::DW_OP_addrx) {
uint64_t Index = Op.getRawOperand(0);
if (auto SA = DU.getAddrOffsetSectionItem(Index))
return SA->Address;
}
}
}
return {};
}
template <class IntPtrT>
bool DwarfInstrProfCorrelator<IntPtrT>::isDIEOfProbe(const DWARFDie &Die) {
const auto &ParentDie = Die.getParent();
if (!Die.isValid() || !ParentDie.isValid() || Die.isNULL())
return false;
if (Die.getTag() != dwarf::DW_TAG_variable)
return false;
if (!ParentDie.isSubprogramDIE())
return false;
if (!Die.hasChildren())
return false;
if (const char *Name = Die.getName(DINameKind::ShortName))
return StringRef(Name).startswith(getInstrProfCountersVarPrefix());
return false;
}
template <class IntPtrT>
void DwarfInstrProfCorrelator<IntPtrT>::correlateProfileDataImpl() {
auto maybeAddProbe = [&](DWARFDie Die) {
if (!isDIEOfProbe(Die))
return;
Optional<const char *> FunctionName;
Optional<uint64_t> CFGHash;
Optional<uint64_t> CounterPtr = getLocation(Die);
auto FunctionPtr =
dwarf::toAddress(Die.getParent().find(dwarf::DW_AT_low_pc));
Optional<uint64_t> NumCounters;
for (const DWARFDie &Child : Die.children()) {
if (Child.getTag() != dwarf::DW_TAG_LLVM_annotation)
continue;
auto AnnotationFormName = Child.find(dwarf::DW_AT_name);
auto AnnotationFormValue = Child.find(dwarf::DW_AT_const_value);
if (!AnnotationFormName || !AnnotationFormValue)
continue;
auto AnnotationNameOrErr = AnnotationFormName->getAsCString();
if (auto Err = AnnotationNameOrErr.takeError()) {
consumeError(std::move(Err));
continue;
}
StringRef AnnotationName = *AnnotationNameOrErr;
if (AnnotationName.compare(
InstrProfCorrelator::FunctionNameAttributeName) == 0) {
if (auto EC =
AnnotationFormValue->getAsCString().moveInto(FunctionName))
consumeError(std::move(EC));
} else if (AnnotationName.compare(
InstrProfCorrelator::CFGHashAttributeName) == 0) {
CFGHash = AnnotationFormValue->getAsUnsignedConstant();
} else if (AnnotationName.compare(
InstrProfCorrelator::NumCountersAttributeName) == 0) {
NumCounters = AnnotationFormValue->getAsUnsignedConstant();
}
}
if (!FunctionName || !CFGHash || !CounterPtr || !NumCounters) {
LLVM_DEBUG(dbgs() << "Incomplete DIE for probe\n\tFunctionName: "
<< FunctionName << "\n\tCFGHash: " << CFGHash
<< "\n\tCounterPtr: " << CounterPtr
<< "\n\tNumCounters: " << NumCounters);
LLVM_DEBUG(Die.dump(dbgs()));
return;
}
uint64_t CountersStart = this->Ctx->CountersSectionStart;
uint64_t CountersEnd = this->Ctx->CountersSectionEnd;
if (*CounterPtr < CountersStart || *CounterPtr >= CountersEnd) {
LLVM_DEBUG(
dbgs() << "CounterPtr out of range for probe\n\tFunction Name: "
<< FunctionName << "\n\tExpected: [0x"
<< Twine::utohexstr(CountersStart) << ", 0x"
<< Twine::utohexstr(CountersEnd) << ")\n\tActual: 0x"
<< Twine::utohexstr(*CounterPtr));
LLVM_DEBUG(Die.dump(dbgs()));
return;
}
if (!FunctionPtr) {
LLVM_DEBUG(dbgs() << "Could not find address of " << *FunctionName
<< "\n");
LLVM_DEBUG(Die.dump(dbgs()));
}
this->addProbe(*FunctionName, *CFGHash, *CounterPtr - CountersStart,
FunctionPtr.getValueOr(0), *NumCounters);
};
for (auto &CU : DICtx->normal_units())
for (const auto &Entry : CU->dies())
maybeAddProbe(DWARFDie(CU.get(), &Entry));
for (auto &CU : DICtx->dwo_units())
for (const auto &Entry : CU->dies())
maybeAddProbe(DWARFDie(CU.get(), &Entry));
}
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