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llvm-project/llvm/lib/LTO/LTO.cpp

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//===-LTO.cpp - LLVM Link Time Optimizer ----------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements functions and classes used to support LTO.
//
//===----------------------------------------------------------------------===//
#include "llvm/LTO/LTO.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/TargetLoweringObjectFileImpl.h"
#include "llvm/IR/AutoUpgrade.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/Metadata.h"
#include "llvm/LTO/LTOBackend.h"
#include "llvm/Linker/IRMover.h"
#include "llvm/Object/ModuleSummaryIndexObjectFile.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/SHA1.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/ThreadPool.h"
#include "llvm/Support/Threading.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/Utils/SplitModule.h"
#include <set>
using namespace llvm;
using namespace lto;
using namespace object;
#define DEBUG_TYPE "lto"
// Returns a unique hash for the Module considering the current list of
// export/import and other global analysis results.
// The hash is produced in \p Key.
static void computeCacheKey(
SmallString<40> &Key, const Config &Conf, const ModuleSummaryIndex &Index,
StringRef ModuleID, const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
const GVSummaryMapTy &DefinedGlobals) {
// Compute the unique hash for this entry.
// This is based on the current compiler version, the module itself, the
// export list, the hash for every single module in the import list, the
// list of ResolvedODR for the module, and the list of preserved symbols.
SHA1 Hasher;
// Start with the compiler revision
Hasher.update(LLVM_VERSION_STRING);
#ifdef HAVE_LLVM_REVISION
Hasher.update(LLVM_REVISION);
#endif
// Include the parts of the LTO configuration that affect code generation.
auto AddString = [&](StringRef Str) {
Hasher.update(Str);
Hasher.update(ArrayRef<uint8_t>{0});
};
auto AddUnsigned = [&](unsigned I) {
uint8_t Data[4];
Data[0] = I;
Data[1] = I >> 8;
Data[2] = I >> 16;
Data[3] = I >> 24;
Hasher.update(ArrayRef<uint8_t>{Data, 4});
};
AddString(Conf.CPU);
// FIXME: Hash more of Options. For now all clients initialize Options from
// command-line flags (which is unsupported in production), but may set
// RelaxELFRelocations. The clang driver can also pass FunctionSections,
// DataSections and DebuggerTuning via command line flags.
AddUnsigned(Conf.Options.RelaxELFRelocations);
AddUnsigned(Conf.Options.FunctionSections);
AddUnsigned(Conf.Options.DataSections);
AddUnsigned((unsigned)Conf.Options.DebuggerTuning);
for (auto &A : Conf.MAttrs)
AddString(A);
AddUnsigned(Conf.RelocModel);
AddUnsigned(Conf.CodeModel);
AddUnsigned(Conf.CGOptLevel);
AddUnsigned(Conf.OptLevel);
AddString(Conf.OptPipeline);
AddString(Conf.AAPipeline);
AddString(Conf.OverrideTriple);
AddString(Conf.DefaultTriple);
// Include the hash for the current module
auto ModHash = Index.getModuleHash(ModuleID);
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
for (auto F : ExportList)
// The export list can impact the internalization, be conservative here
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&F, sizeof(F)));
// Include the hash for every module we import functions from
for (auto &Entry : ImportList) {
auto ModHash = Index.getModuleHash(Entry.first());
Hasher.update(ArrayRef<uint8_t>((uint8_t *)&ModHash[0], sizeof(ModHash)));
}
// Include the hash for the resolved ODR.
for (auto &Entry : ResolvedODR) {
Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&Entry.first,
sizeof(GlobalValue::GUID)));
Hasher.update(ArrayRef<uint8_t>((const uint8_t *)&Entry.second,
sizeof(GlobalValue::LinkageTypes)));
}
// Include the hash for the linkage type to reflect internalization and weak
// resolution.
for (auto &GS : DefinedGlobals) {
GlobalValue::LinkageTypes Linkage = GS.second->linkage();
Hasher.update(
ArrayRef<uint8_t>((const uint8_t *)&Linkage, sizeof(Linkage)));
}
if (!Conf.SampleProfile.empty()) {
auto FileOrErr = MemoryBuffer::getFile(Conf.SampleProfile);
if (FileOrErr)
Hasher.update(FileOrErr.get()->getBuffer());
}
Key = toHex(Hasher.result());
}
static void thinLTOResolveWeakForLinkerGUID(
GlobalValueSummaryList &GVSummaryList, GlobalValue::GUID GUID,
DenseSet<GlobalValueSummary *> &GlobalInvolvedWithAlias,
function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
isPrevailing,
function_ref<void(StringRef, GlobalValue::GUID, GlobalValue::LinkageTypes)>
recordNewLinkage) {
for (auto &S : GVSummaryList) {
GlobalValue::LinkageTypes OriginalLinkage = S->linkage();
if (!GlobalValue::isWeakForLinker(OriginalLinkage))
continue;
// We need to emit only one of these. The prevailing module will keep it,
// but turned into a weak, while the others will drop it when possible.
// This is both a compile-time optimization and a correctness
// transformation. This is necessary for correctness when we have exported
// a reference - we need to convert the linkonce to weak to
// ensure a copy is kept to satisfy the exported reference.
// FIXME: We may want to split the compile time and correctness
// aspects into separate routines.
if (isPrevailing(GUID, S.get())) {
if (GlobalValue::isLinkOnceLinkage(OriginalLinkage))
S->setLinkage(GlobalValue::getWeakLinkage(
GlobalValue::isLinkOnceODRLinkage(OriginalLinkage)));
}
// Alias and aliasee can't be turned into available_externally.
else if (!isa<AliasSummary>(S.get()) &&
!GlobalInvolvedWithAlias.count(S.get()))
S->setLinkage(GlobalValue::AvailableExternallyLinkage);
if (S->linkage() != OriginalLinkage)
recordNewLinkage(S->modulePath(), GUID, S->linkage());
}
}
// Resolve Weak and LinkOnce values in the \p Index.
//
// We'd like to drop these functions if they are no longer referenced in the
// current module. However there is a chance that another module is still
// referencing them because of the import. We make sure we always emit at least
// one copy.
void llvm::thinLTOResolveWeakForLinkerInIndex(
ModuleSummaryIndex &Index,
function_ref<bool(GlobalValue::GUID, const GlobalValueSummary *)>
isPrevailing,
function_ref<void(StringRef, GlobalValue::GUID, GlobalValue::LinkageTypes)>
recordNewLinkage) {
// We won't optimize the globals that are referenced by an alias for now
// Ideally we should turn the alias into a global and duplicate the definition
// when needed.
DenseSet<GlobalValueSummary *> GlobalInvolvedWithAlias;
for (auto &I : Index)
for (auto &S : I.second)
if (auto AS = dyn_cast<AliasSummary>(S.get()))
GlobalInvolvedWithAlias.insert(&AS->getAliasee());
for (auto &I : Index)
thinLTOResolveWeakForLinkerGUID(I.second, I.first, GlobalInvolvedWithAlias,
isPrevailing, recordNewLinkage);
}
static void thinLTOInternalizeAndPromoteGUID(
GlobalValueSummaryList &GVSummaryList, GlobalValue::GUID GUID,
function_ref<bool(StringRef, GlobalValue::GUID)> isExported) {
for (auto &S : GVSummaryList) {
if (isExported(S->modulePath(), GUID)) {
if (GlobalValue::isLocalLinkage(S->linkage()))
S->setLinkage(GlobalValue::ExternalLinkage);
} else if (!GlobalValue::isLocalLinkage(S->linkage()))
S->setLinkage(GlobalValue::InternalLinkage);
}
}
// Update the linkages in the given \p Index to mark exported values
// as external and non-exported values as internal.
void llvm::thinLTOInternalizeAndPromoteInIndex(
ModuleSummaryIndex &Index,
function_ref<bool(StringRef, GlobalValue::GUID)> isExported) {
for (auto &I : Index)
thinLTOInternalizeAndPromoteGUID(I.second, I.first, isExported);
}
struct InputFile::InputModule {
BitcodeModule BM;
std::unique_ptr<Module> Mod;
// The range of ModuleSymbolTable entries for this input module.
size_t SymBegin, SymEnd;
};
// Requires a destructor for std::vector<InputModule>.
InputFile::~InputFile() = default;
Expected<std::unique_ptr<InputFile>> InputFile::create(MemoryBufferRef Object) {
std::unique_ptr<InputFile> File(new InputFile);
ErrorOr<MemoryBufferRef> BCOrErr =
IRObjectFile::findBitcodeInMemBuffer(Object);
if (!BCOrErr)
return errorCodeToError(BCOrErr.getError());
Expected<std::vector<BitcodeModule>> BMsOrErr =
getBitcodeModuleList(*BCOrErr);
if (!BMsOrErr)
return BMsOrErr.takeError();
if (BMsOrErr->empty())
return make_error<StringError>("Bitcode file does not contain any modules",
inconvertibleErrorCode());
// Create an InputModule for each module in the InputFile, and add it to the
// ModuleSymbolTable.
for (auto BM : *BMsOrErr) {
Expected<std::unique_ptr<Module>> MOrErr =
BM.getLazyModule(File->Ctx, /*ShouldLazyLoadMetadata*/ true,
/*IsImporting*/ false);
if (!MOrErr)
return MOrErr.takeError();
size_t SymBegin = File->SymTab.symbols().size();
File->SymTab.addModule(MOrErr->get());
size_t SymEnd = File->SymTab.symbols().size();
for (const auto &C : (*MOrErr)->getComdatSymbolTable()) {
auto P = File->ComdatMap.insert(
std::make_pair(&C.second, File->Comdats.size()));
assert(P.second);
(void)P;
File->Comdats.push_back(C.first());
}
File->Mods.push_back({BM, std::move(*MOrErr), SymBegin, SymEnd});
}
return std::move(File);
}
Expected<int> InputFile::Symbol::getComdatIndex() const {
if (!isGV())
return -1;
const GlobalObject *GO = getGV()->getBaseObject();
if (!GO)
return make_error<StringError>("Unable to determine comdat of alias!",
inconvertibleErrorCode());
if (const Comdat *C = GO->getComdat()) {
auto I = File->ComdatMap.find(C);
assert(I != File->ComdatMap.end());
return I->second;
}
return -1;
}
Expected<std::string> InputFile::getLinkerOpts() {
std::string LinkerOpts;
raw_string_ostream LOS(LinkerOpts);
// Extract linker options from module metadata.
for (InputModule &Mod : Mods) {
std::unique_ptr<Module> &M = Mod.Mod;
if (auto E = M->materializeMetadata())
return std::move(E);
if (Metadata *Val = M->getModuleFlag("Linker Options")) {
MDNode *LinkerOptions = cast<MDNode>(Val);
for (const MDOperand &MDOptions : LinkerOptions->operands())
for (const MDOperand &MDOption : cast<MDNode>(MDOptions)->operands())
LOS << " " << cast<MDString>(MDOption)->getString();
}
}
// Synthesize export flags for symbols with dllexport storage.
const Triple TT(Mods[0].Mod->getTargetTriple());
Mangler M;
for (const ModuleSymbolTable::Symbol &Sym : SymTab.symbols())
if (auto *GV = Sym.dyn_cast<GlobalValue*>())
emitLinkerFlagsForGlobalCOFF(LOS, GV, TT, M);
LOS.flush();
return LinkerOpts;
}
StringRef InputFile::getName() const {
return Mods[0].BM.getModuleIdentifier();
}
StringRef InputFile::getSourceFileName() const {
return Mods[0].Mod->getSourceFileName();
}
iterator_range<InputFile::symbol_iterator>
InputFile::module_symbols(InputModule &IM) {
return llvm::make_range(
symbol_iterator(SymTab.symbols().data() + IM.SymBegin, SymTab, this),
symbol_iterator(SymTab.symbols().data() + IM.SymEnd, SymTab, this));
}
LTO::RegularLTOState::RegularLTOState(unsigned ParallelCodeGenParallelismLevel,
Config &Conf)
: ParallelCodeGenParallelismLevel(ParallelCodeGenParallelismLevel),
Ctx(Conf) {}
LTO::ThinLTOState::ThinLTOState(ThinBackend Backend) : Backend(Backend) {
if (!Backend)
this->Backend =
createInProcessThinBackend(llvm::heavyweight_hardware_concurrency());
}
LTO::LTO(Config Conf, ThinBackend Backend,
unsigned ParallelCodeGenParallelismLevel)
: Conf(std::move(Conf)),
RegularLTO(ParallelCodeGenParallelismLevel, this->Conf),
ThinLTO(std::move(Backend)) {}
// Requires a destructor for MapVector<BitcodeModule>.
LTO::~LTO() = default;
// Add the given symbol to the GlobalResolutions map, and resolve its partition.
void LTO::addSymbolToGlobalRes(SmallPtrSet<GlobalValue *, 8> &Used,
const InputFile::Symbol &Sym,
SymbolResolution Res, unsigned Partition) {
GlobalValue *GV = Sym.isGV() ? Sym.getGV() : nullptr;
auto &GlobalRes = GlobalResolutions[Sym.getName()];
if (GV) {
GlobalRes.UnnamedAddr &= GV->hasGlobalUnnamedAddr();
if (Res.Prevailing)
GlobalRes.IRName = GV->getName();
}
// Set the partition to external if we know it is used elsewhere, e.g.
// it is visible to a regular object, is referenced from llvm.compiler_used,
// or was already recorded as being referenced from a different partition.
if (Res.VisibleToRegularObj || (GV && Used.count(GV)) ||
(GlobalRes.Partition != GlobalResolution::Unknown &&
GlobalRes.Partition != Partition)) {
GlobalRes.Partition = GlobalResolution::External;
} else
// First recorded reference, save the current partition.
GlobalRes.Partition = Partition;
// Flag as visible outside of ThinLTO if visible from a regular object or
// if this is a reference in the regular LTO partition.
GlobalRes.VisibleOutsideThinLTO |=
(Res.VisibleToRegularObj || (Partition == GlobalResolution::RegularLTO));
}
static void writeToResolutionFile(raw_ostream &OS, InputFile *Input,
ArrayRef<SymbolResolution> Res) {
StringRef Path = Input->getName();
OS << Path << '\n';
auto ResI = Res.begin();
for (const InputFile::Symbol &Sym : Input->symbols()) {
assert(ResI != Res.end());
SymbolResolution Res = *ResI++;
OS << "-r=" << Path << ',' << Sym.getName() << ',';
if (Res.Prevailing)
OS << 'p';
if (Res.FinalDefinitionInLinkageUnit)
OS << 'l';
if (Res.VisibleToRegularObj)
OS << 'x';
OS << '\n';
}
OS.flush();
assert(ResI == Res.end());
}
Error LTO::add(std::unique_ptr<InputFile> Input,
ArrayRef<SymbolResolution> Res) {
assert(!CalledGetMaxTasks);
if (Conf.ResolutionFile)
writeToResolutionFile(*Conf.ResolutionFile, Input.get(), Res);
const SymbolResolution *ResI = Res.begin();
for (InputFile::InputModule &IM : Input->Mods)
if (Error Err = addModule(*Input, IM, ResI, Res.end()))
return Err;
assert(ResI == Res.end());
return Error::success();
}
Error LTO::addModule(InputFile &Input, InputFile::InputModule &IM,
const SymbolResolution *&ResI,
const SymbolResolution *ResE) {
// FIXME: move to backend
Module &M = *IM.Mod;
if (M.getDataLayoutStr().empty())
return make_error<StringError>("input module has no datalayout",
inconvertibleErrorCode());
if (!Conf.OverrideTriple.empty())
M.setTargetTriple(Conf.OverrideTriple);
else if (M.getTargetTriple().empty())
M.setTargetTriple(Conf.DefaultTriple);
Expected<bool> HasThinLTOSummary = IM.BM.hasSummary();
if (!HasThinLTOSummary)
return HasThinLTOSummary.takeError();
if (*HasThinLTOSummary)
return addThinLTO(IM.BM, M, Input.module_symbols(IM), ResI, ResE);
else
return addRegularLTO(IM.BM, ResI, ResE);
}
// Add a regular LTO object to the link.
Error LTO::addRegularLTO(BitcodeModule BM, const SymbolResolution *&ResI,
const SymbolResolution *ResE) {
if (!RegularLTO.CombinedModule) {
RegularLTO.CombinedModule =
llvm::make_unique<Module>("ld-temp.o", RegularLTO.Ctx);
RegularLTO.Mover = llvm::make_unique<IRMover>(*RegularLTO.CombinedModule);
}
Expected<std::unique_ptr<Module>> MOrErr =
BM.getLazyModule(RegularLTO.Ctx, /*ShouldLazyLoadMetadata*/ true,
/*IsImporting*/ false);
if (!MOrErr)
return MOrErr.takeError();
Module &M = **MOrErr;
if (Error Err = M.materializeMetadata())
return Err;
UpgradeDebugInfo(M);
ModuleSymbolTable SymTab;
SymTab.addModule(&M);
SmallPtrSet<GlobalValue *, 8> Used;
collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
std::vector<GlobalValue *> Keep;
for (GlobalVariable &GV : M.globals())
if (GV.hasAppendingLinkage())
Keep.push_back(&GV);
DenseSet<GlobalObject *> AliasedGlobals;
for (auto &GA : M.aliases())
if (GlobalObject *GO = GA.getBaseObject())
AliasedGlobals.insert(GO);
for (const InputFile::Symbol &Sym :
make_range(InputFile::symbol_iterator(SymTab.symbols().begin(), SymTab,
nullptr),
InputFile::symbol_iterator(SymTab.symbols().end(), SymTab,
nullptr))) {
assert(ResI != ResE);
SymbolResolution Res = *ResI++;
addSymbolToGlobalRes(Used, Sym, Res, 0);
if (Sym.isGV()) {
GlobalValue *GV = Sym.getGV();
if (Res.Prevailing) {
if (Sym.getFlags() & object::BasicSymbolRef::SF_Undefined)
continue;
Keep.push_back(GV);
switch (GV->getLinkage()) {
default:
break;
case GlobalValue::LinkOnceAnyLinkage:
GV->setLinkage(GlobalValue::WeakAnyLinkage);
break;
case GlobalValue::LinkOnceODRLinkage:
GV->setLinkage(GlobalValue::WeakODRLinkage);
break;
}
} else if (isa<GlobalObject>(GV) &&
(GV->hasLinkOnceODRLinkage() || GV->hasWeakODRLinkage() ||
GV->hasAvailableExternallyLinkage()) &&
!AliasedGlobals.count(cast<GlobalObject>(GV))) {
// Either of the above three types of linkage indicates that the
// chosen prevailing symbol will have the same semantics as this copy of
// the symbol, so we can link it with available_externally linkage. We
// only need to do this if the symbol is undefined.
GlobalValue *CombinedGV =
RegularLTO.CombinedModule->getNamedValue(GV->getName());
if (!CombinedGV || CombinedGV->isDeclaration()) {
Keep.push_back(GV);
GV->setLinkage(GlobalValue::AvailableExternallyLinkage);
cast<GlobalObject>(GV)->setComdat(nullptr);
}
}
}
// Common resolution: collect the maximum size/alignment over all commons.
// We also record if we see an instance of a common as prevailing, so that
// if none is prevailing we can ignore it later.
if (Sym.getFlags() & object::BasicSymbolRef::SF_Common) {
// FIXME: We should figure out what to do about commons defined by asm.
// For now they aren't reported correctly by ModuleSymbolTable.
auto &CommonRes = RegularLTO.Commons[Sym.getGV()->getName()];
CommonRes.Size = std::max(CommonRes.Size, Sym.getCommonSize());
CommonRes.Align = std::max(CommonRes.Align, Sym.getCommonAlignment());
CommonRes.Prevailing |= Res.Prevailing;
}
// FIXME: use proposed local attribute for FinalDefinitionInLinkageUnit.
}
return RegularLTO.Mover->move(std::move(*MOrErr), Keep,
[](GlobalValue &, IRMover::ValueAdder) {},
/* IsPerformingImport */ false);
}
// Add a ThinLTO object to the link.
// FIXME: This function should not need to take as many parameters once we have
// a bitcode symbol table.
Error LTO::addThinLTO(BitcodeModule BM, Module &M,
iterator_range<InputFile::symbol_iterator> Syms,
const SymbolResolution *&ResI,
const SymbolResolution *ResE) {
SmallPtrSet<GlobalValue *, 8> Used;
collectUsedGlobalVariables(M, Used, /*CompilerUsed*/ false);
Expected<std::unique_ptr<ModuleSummaryIndex>> SummaryOrErr = BM.getSummary();
if (!SummaryOrErr)
return SummaryOrErr.takeError();
ThinLTO.CombinedIndex.mergeFrom(std::move(*SummaryOrErr),
ThinLTO.ModuleMap.size());
for (const InputFile::Symbol &Sym : Syms) {
assert(ResI != ResE);
SymbolResolution Res = *ResI++;
addSymbolToGlobalRes(Used, Sym, Res, ThinLTO.ModuleMap.size() + 1);
if (Res.Prevailing && Sym.isGV())
ThinLTO.PrevailingModuleForGUID[Sym.getGV()->getGUID()] =
BM.getModuleIdentifier();
}
if (!ThinLTO.ModuleMap.insert({BM.getModuleIdentifier(), BM}).second)
return make_error<StringError>(
"Expected at most one ThinLTO module per bitcode file",
inconvertibleErrorCode());
return Error::success();
}
unsigned LTO::getMaxTasks() const {
CalledGetMaxTasks = true;
return RegularLTO.ParallelCodeGenParallelismLevel + ThinLTO.ModuleMap.size();
}
Error LTO::run(AddStreamFn AddStream, NativeObjectCache Cache) {
// Save the status of having a regularLTO combined module, as
// this is needed for generating the ThinLTO Task ID, and
// the CombinedModule will be moved at the end of runRegularLTO.
bool HasRegularLTO = RegularLTO.CombinedModule != nullptr;
// Invoke regular LTO if there was a regular LTO module to start with.
if (HasRegularLTO)
if (auto E = runRegularLTO(AddStream))
return E;
return runThinLTO(AddStream, Cache, HasRegularLTO);
}
Error LTO::runRegularLTO(AddStreamFn AddStream) {
// Make sure commons have the right size/alignment: we kept the largest from
// all the prevailing when adding the inputs, and we apply it here.
const DataLayout &DL = RegularLTO.CombinedModule->getDataLayout();
for (auto &I : RegularLTO.Commons) {
if (!I.second.Prevailing)
// Don't do anything if no instance of this common was prevailing.
continue;
GlobalVariable *OldGV = RegularLTO.CombinedModule->getNamedGlobal(I.first);
if (OldGV && DL.getTypeAllocSize(OldGV->getValueType()) == I.second.Size) {
// Don't create a new global if the type is already correct, just make
// sure the alignment is correct.
OldGV->setAlignment(I.second.Align);
continue;
}
ArrayType *Ty =
ArrayType::get(Type::getInt8Ty(RegularLTO.Ctx), I.second.Size);
auto *GV = new GlobalVariable(*RegularLTO.CombinedModule, Ty, false,
GlobalValue::CommonLinkage,
ConstantAggregateZero::get(Ty), "");
GV->setAlignment(I.second.Align);
if (OldGV) {
OldGV->replaceAllUsesWith(ConstantExpr::getBitCast(GV, OldGV->getType()));
GV->takeName(OldGV);
OldGV->eraseFromParent();
} else {
GV->setName(I.first);
}
}
if (Conf.PreOptModuleHook &&
!Conf.PreOptModuleHook(0, *RegularLTO.CombinedModule))
return Error::success();
if (!Conf.CodeGenOnly) {
for (const auto &R : GlobalResolutions) {
if (R.second.IRName.empty())
continue;
if (R.second.Partition != 0 &&
R.second.Partition != GlobalResolution::External)
continue;
GlobalValue *GV =
RegularLTO.CombinedModule->getNamedValue(R.second.IRName);
// Ignore symbols defined in other partitions.
if (!GV || GV->hasLocalLinkage())
continue;
GV->setUnnamedAddr(R.second.UnnamedAddr ? GlobalValue::UnnamedAddr::Global
: GlobalValue::UnnamedAddr::None);
if (R.second.Partition == 0)
GV->setLinkage(GlobalValue::InternalLinkage);
}
if (Conf.PostInternalizeModuleHook &&
!Conf.PostInternalizeModuleHook(0, *RegularLTO.CombinedModule))
return Error::success();
}
return backend(Conf, AddStream, RegularLTO.ParallelCodeGenParallelismLevel,
std::move(RegularLTO.CombinedModule), ThinLTO.CombinedIndex);
}
/// This class defines the interface to the ThinLTO backend.
class lto::ThinBackendProc {
protected:
Config &Conf;
ModuleSummaryIndex &CombinedIndex;
const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries;
public:
ThinBackendProc(Config &Conf, ModuleSummaryIndex &CombinedIndex,
const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries)
: Conf(Conf), CombinedIndex(CombinedIndex),
ModuleToDefinedGVSummaries(ModuleToDefinedGVSummaries) {}
virtual ~ThinBackendProc() {}
virtual Error start(
unsigned Task, BitcodeModule BM,
const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
MapVector<StringRef, BitcodeModule> &ModuleMap) = 0;
virtual Error wait() = 0;
};
namespace {
class InProcessThinBackend : public ThinBackendProc {
ThreadPool BackendThreadPool;
AddStreamFn AddStream;
NativeObjectCache Cache;
Optional<Error> Err;
std::mutex ErrMu;
public:
InProcessThinBackend(
Config &Conf, ModuleSummaryIndex &CombinedIndex,
unsigned ThinLTOParallelismLevel,
const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
AddStreamFn AddStream, NativeObjectCache Cache)
: ThinBackendProc(Conf, CombinedIndex, ModuleToDefinedGVSummaries),
BackendThreadPool(ThinLTOParallelismLevel),
AddStream(std::move(AddStream)), Cache(std::move(Cache)) {}
Error runThinLTOBackendThread(
AddStreamFn AddStream, NativeObjectCache Cache, unsigned Task,
BitcodeModule BM, ModuleSummaryIndex &CombinedIndex,
const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
const GVSummaryMapTy &DefinedGlobals,
MapVector<StringRef, BitcodeModule> &ModuleMap) {
auto RunThinBackend = [&](AddStreamFn AddStream) {
LTOLLVMContext BackendContext(Conf);
Expected<std::unique_ptr<Module>> MOrErr = BM.parseModule(BackendContext);
if (!MOrErr)
return MOrErr.takeError();
return thinBackend(Conf, Task, AddStream, **MOrErr, CombinedIndex,
ImportList, DefinedGlobals, ModuleMap);
};
auto ModuleID = BM.getModuleIdentifier();
if (!Cache || !CombinedIndex.modulePaths().count(ModuleID) ||
all_of(CombinedIndex.getModuleHash(ModuleID),
[](uint32_t V) { return V == 0; }))
// Cache disabled or no entry for this module in the combined index or
// no module hash.
return RunThinBackend(AddStream);
SmallString<40> Key;
// The module may be cached, this helps handling it.
computeCacheKey(Key, Conf, CombinedIndex, ModuleID, ImportList, ExportList,
ResolvedODR, DefinedGlobals);
if (AddStreamFn CacheAddStream = Cache(Task, Key))
return RunThinBackend(CacheAddStream);
return Error::success();
}
Error start(
unsigned Task, BitcodeModule BM,
const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
MapVector<StringRef, BitcodeModule> &ModuleMap) override {
StringRef ModulePath = BM.getModuleIdentifier();
assert(ModuleToDefinedGVSummaries.count(ModulePath));
const GVSummaryMapTy &DefinedGlobals =
ModuleToDefinedGVSummaries.find(ModulePath)->second;
BackendThreadPool.async(
[=](BitcodeModule BM, ModuleSummaryIndex &CombinedIndex,
const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>
&ResolvedODR,
const GVSummaryMapTy &DefinedGlobals,
MapVector<StringRef, BitcodeModule> &ModuleMap) {
Error E = runThinLTOBackendThread(
AddStream, Cache, Task, BM, CombinedIndex, ImportList,
ExportList, ResolvedODR, DefinedGlobals, ModuleMap);
if (E) {
std::unique_lock<std::mutex> L(ErrMu);
if (Err)
Err = joinErrors(std::move(*Err), std::move(E));
else
Err = std::move(E);
}
},
BM, std::ref(CombinedIndex), std::ref(ImportList),
std::ref(ExportList), std::ref(ResolvedODR), std::ref(DefinedGlobals),
std::ref(ModuleMap));
return Error::success();
}
Error wait() override {
BackendThreadPool.wait();
if (Err)
return std::move(*Err);
else
return Error::success();
}
};
} // end anonymous namespace
ThinBackend lto::createInProcessThinBackend(unsigned ParallelismLevel) {
return [=](Config &Conf, ModuleSummaryIndex &CombinedIndex,
const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
AddStreamFn AddStream, NativeObjectCache Cache) {
return llvm::make_unique<InProcessThinBackend>(
Conf, CombinedIndex, ParallelismLevel, ModuleToDefinedGVSummaries,
AddStream, Cache);
};
}
// Given the original \p Path to an output file, replace any path
// prefix matching \p OldPrefix with \p NewPrefix. Also, create the
// resulting directory if it does not yet exist.
std::string lto::getThinLTOOutputFile(const std::string &Path,
const std::string &OldPrefix,
const std::string &NewPrefix) {
if (OldPrefix.empty() && NewPrefix.empty())
return Path;
SmallString<128> NewPath(Path);
llvm::sys::path::replace_path_prefix(NewPath, OldPrefix, NewPrefix);
StringRef ParentPath = llvm::sys::path::parent_path(NewPath.str());
if (!ParentPath.empty()) {
// Make sure the new directory exists, creating it if necessary.
if (std::error_code EC = llvm::sys::fs::create_directories(ParentPath))
llvm::errs() << "warning: could not create directory '" << ParentPath
<< "': " << EC.message() << '\n';
}
return NewPath.str();
}
namespace {
class WriteIndexesThinBackend : public ThinBackendProc {
std::string OldPrefix, NewPrefix;
bool ShouldEmitImportsFiles;
std::string LinkedObjectsFileName;
std::unique_ptr<llvm::raw_fd_ostream> LinkedObjectsFile;
public:
WriteIndexesThinBackend(
Config &Conf, ModuleSummaryIndex &CombinedIndex,
const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
std::string OldPrefix, std::string NewPrefix, bool ShouldEmitImportsFiles,
std::string LinkedObjectsFileName)
: ThinBackendProc(Conf, CombinedIndex, ModuleToDefinedGVSummaries),
OldPrefix(OldPrefix), NewPrefix(NewPrefix),
ShouldEmitImportsFiles(ShouldEmitImportsFiles),
LinkedObjectsFileName(LinkedObjectsFileName) {}
Error start(
unsigned Task, BitcodeModule BM,
const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const std::map<GlobalValue::GUID, GlobalValue::LinkageTypes> &ResolvedODR,
MapVector<StringRef, BitcodeModule> &ModuleMap) override {
StringRef ModulePath = BM.getModuleIdentifier();
std::string NewModulePath =
getThinLTOOutputFile(ModulePath, OldPrefix, NewPrefix);
std::error_code EC;
if (!LinkedObjectsFileName.empty()) {
if (!LinkedObjectsFile) {
LinkedObjectsFile = llvm::make_unique<raw_fd_ostream>(
LinkedObjectsFileName, EC, sys::fs::OpenFlags::F_None);
if (EC)
return errorCodeToError(EC);
}
*LinkedObjectsFile << NewModulePath << '\n';
}
std::map<std::string, GVSummaryMapTy> ModuleToSummariesForIndex;
gatherImportedSummariesForModule(ModulePath, ModuleToDefinedGVSummaries,
ImportList, ModuleToSummariesForIndex);
raw_fd_ostream OS(NewModulePath + ".thinlto.bc", EC,
sys::fs::OpenFlags::F_None);
if (EC)
return errorCodeToError(EC);
WriteIndexToFile(CombinedIndex, OS, &ModuleToSummariesForIndex);
if (ShouldEmitImportsFiles)
return errorCodeToError(
EmitImportsFiles(ModulePath, NewModulePath + ".imports", ImportList));
return Error::success();
}
Error wait() override { return Error::success(); }
};
} // end anonymous namespace
ThinBackend lto::createWriteIndexesThinBackend(std::string OldPrefix,
std::string NewPrefix,
bool ShouldEmitImportsFiles,
std::string LinkedObjectsFile) {
return [=](Config &Conf, ModuleSummaryIndex &CombinedIndex,
const StringMap<GVSummaryMapTy> &ModuleToDefinedGVSummaries,
AddStreamFn AddStream, NativeObjectCache Cache) {
return llvm::make_unique<WriteIndexesThinBackend>(
Conf, CombinedIndex, ModuleToDefinedGVSummaries, OldPrefix, NewPrefix,
ShouldEmitImportsFiles, LinkedObjectsFile);
};
}
Error LTO::runThinLTO(AddStreamFn AddStream, NativeObjectCache Cache,
bool HasRegularLTO) {
if (ThinLTO.ModuleMap.empty())
return Error::success();
if (Conf.CombinedIndexHook && !Conf.CombinedIndexHook(ThinLTO.CombinedIndex))
return Error::success();
// Collect for each module the list of function it defines (GUID ->
// Summary).
StringMap<std::map<GlobalValue::GUID, GlobalValueSummary *>>
ModuleToDefinedGVSummaries(ThinLTO.ModuleMap.size());
ThinLTO.CombinedIndex.collectDefinedGVSummariesPerModule(
ModuleToDefinedGVSummaries);
// Create entries for any modules that didn't have any GV summaries
// (either they didn't have any GVs to start with, or we suppressed
// generation of the summaries because they e.g. had inline assembly
// uses that couldn't be promoted/renamed on export). This is so
// InProcessThinBackend::start can still launch a backend thread, which
// is passed the map of summaries for the module, without any special
// handling for this case.
for (auto &Mod : ThinLTO.ModuleMap)
if (!ModuleToDefinedGVSummaries.count(Mod.first))
ModuleToDefinedGVSummaries.try_emplace(Mod.first);
StringMap<FunctionImporter::ImportMapTy> ImportLists(
ThinLTO.ModuleMap.size());
StringMap<FunctionImporter::ExportSetTy> ExportLists(
ThinLTO.ModuleMap.size());
StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>> ResolvedODR;
if (Conf.OptLevel > 0) {
// Compute "dead" symbols, we don't want to import/export these!
DenseSet<GlobalValue::GUID> GUIDPreservedSymbols;
for (auto &Res : GlobalResolutions) {
if (Res.second.VisibleOutsideThinLTO &&
// IRName will be defined if we have seen the prevailing copy of
// this value. If not, no need to preserve any ThinLTO copies.
!Res.second.IRName.empty())
GUIDPreservedSymbols.insert(GlobalValue::getGUID(Res.second.IRName));
}
auto DeadSymbols =
computeDeadSymbols(ThinLTO.CombinedIndex, GUIDPreservedSymbols);
ComputeCrossModuleImport(ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
ImportLists, ExportLists, &DeadSymbols);
std::set<GlobalValue::GUID> ExportedGUIDs;
for (auto &Res : GlobalResolutions) {
// First check if the symbol was flagged as having external references.
if (Res.second.Partition != GlobalResolution::External)
continue;
// IRName will be defined if we have seen the prevailing copy of
// this value. If not, no need to mark as exported from a ThinLTO
// partition (and we can't get the GUID).
if (Res.second.IRName.empty())
continue;
auto GUID = GlobalValue::getGUID(Res.second.IRName);
// Mark exported unless index-based analysis determined it to be dead.
if (!DeadSymbols.count(GUID))
ExportedGUIDs.insert(GlobalValue::getGUID(Res.second.IRName));
}
auto isPrevailing = [&](GlobalValue::GUID GUID,
const GlobalValueSummary *S) {
return ThinLTO.PrevailingModuleForGUID[GUID] == S->modulePath();
};
auto isExported = [&](StringRef ModuleIdentifier, GlobalValue::GUID GUID) {
const auto &ExportList = ExportLists.find(ModuleIdentifier);
return (ExportList != ExportLists.end() &&
ExportList->second.count(GUID)) ||
ExportedGUIDs.count(GUID);
};
thinLTOInternalizeAndPromoteInIndex(ThinLTO.CombinedIndex, isExported);
auto recordNewLinkage = [&](StringRef ModuleIdentifier,
GlobalValue::GUID GUID,
GlobalValue::LinkageTypes NewLinkage) {
ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
};
thinLTOResolveWeakForLinkerInIndex(ThinLTO.CombinedIndex, isPrevailing,
recordNewLinkage);
}
std::unique_ptr<ThinBackendProc> BackendProc =
ThinLTO.Backend(Conf, ThinLTO.CombinedIndex, ModuleToDefinedGVSummaries,
AddStream, Cache);
// Task numbers start at ParallelCodeGenParallelismLevel if an LTO
// module is present, as tasks 0 through ParallelCodeGenParallelismLevel-1
// are reserved for parallel code generation partitions.
unsigned Task =
HasRegularLTO ? RegularLTO.ParallelCodeGenParallelismLevel : 0;
for (auto &Mod : ThinLTO.ModuleMap) {
if (Error E = BackendProc->start(Task, Mod.second, ImportLists[Mod.first],
ExportLists[Mod.first],
ResolvedODR[Mod.first], ThinLTO.ModuleMap))
return E;
++Task;
}
return BackendProc->wait();
}
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