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ThinLTOCodeGenerator.cpp
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//===-ThinLTOCodeGenerator.cpp - LLVM Link Time Optimizer -----------------===//
//
// 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 implements the Thin Link Time Optimization library. This library is
// intended to be used by linker to optimize code at link time.
//
//===----------------------------------------------------------------------===//
#include "llvm/LTO/legacy/ThinLTOCodeGenerator.h"
#include "llvm/CAS/ActionCache.h"
#include "llvm/CAS/ObjectStore.h"
#include "llvm/RemoteCachingService/Client.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/ADT/ScopeExit.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/ModuleSummaryAnalysis.h"
#include "llvm/Analysis/ProfileSummaryInfo.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Bitcode/BitcodeReader.h"
#include "llvm/Bitcode/BitcodeWriter.h"
#include "llvm/Bitcode/BitcodeWriterPass.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/DiagnosticPrinter.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LLVMRemarkStreamer.h"
#include "llvm/IR/Mangler.h"
#include "llvm/IR/PassTimingInfo.h"
#include "llvm/IR/Verifier.h"
#include "llvm/IRReader/IRReader.h"
#include "llvm/LTO/LTO.h"
#include "llvm/LTO/SummaryBasedOptimizations.h"
#include "llvm/MC/TargetRegistry.h"
#include "llvm/Object/IRObjectFile.h"
#include "llvm/Passes/PassBuilder.h"
#include "llvm/Passes/StandardInstrumentations.h"
#include "llvm/Remarks/HotnessThresholdParser.h"
#include "llvm/Support/CachePruning.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Error.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/FormatVariadic.h"
#include "llvm/Support/Path.h"
#include "llvm/Support/Process.h"
#include "llvm/Support/SHA1.h"
#include "llvm/Support/ScopedDurationTimer.h"
#include "llvm/Support/SmallVectorMemoryBuffer.h"
#include "llvm/Support/ThreadPool.h"
#include "llvm/Support/Threading.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/TargetParser/SubtargetFeature.h"
#include "llvm/Transforms/IPO/FunctionAttrs.h"
#include "llvm/Transforms/IPO/FunctionImport.h"
#include "llvm/Transforms/IPO/Internalize.h"
#include "llvm/Transforms/IPO/WholeProgramDevirt.h"
#include "llvm/Transforms/ObjCARC.h"
#include "llvm/Transforms/Utils/FunctionImportUtils.h"
#include <memory>
#include <numeric>
#include <queue>
#if !defined(_MSC_VER) && !defined(__MINGW32__)
#include <unistd.h>
#else
#include <io.h>
#endif
using namespace llvm;
#define DEBUG_TYPE "thinlto"
namespace llvm {
// Flags -discard-value-names, defined in LTOCodeGenerator.cpp
extern cl::opt<bool> LTODiscardValueNames;
extern cl::opt<std::string> RemarksFilename;
extern cl::opt<std::string> RemarksPasses;
extern cl::opt<bool> RemarksWithHotness;
extern cl::opt<std::optional<uint64_t>, false, remarks::HotnessThresholdParser>
RemarksHotnessThreshold;
extern cl::opt<std::string> RemarksFormat;
}
namespace {
// Default to using all available threads in the system, but using only one
// thred per core, as indicated by the usage of
// heavyweight_hardware_concurrency() below.
static cl::opt<int> ThreadCount("threads", cl::init(0));
static cl::opt<bool> CacheLogging(
"thinlto-cache-logging", cl::desc("Enable logging for thinLTO caching"),
cl::init((bool)sys::Process::GetEnv("LLVM_THINLTO_CACHE_LOGGING")),
cl::Hidden);
static cl::opt<bool> DeterministicCheck(
"thinlto-deterministic-check",
cl::desc("Enable deterministic check for thinLTO caching"),
cl::init((bool)sys::Process::GetEnv(
"LLVM_CACHE_CHECK_REPRODUCIBLE_CACHING_ISSUES")),
cl::Hidden);
static cl::opt<bool> StrictCASErrors(
"thinlto-strict-cas-errors",
cl::desc("Treat CAS errors during ThinLTO as fatal errors"),
cl::init((bool)sys::Process::GetEnv("LLVM_THINLTO_STRICT_CAS_ERRORS")),
cl::Hidden);
class LoggingStream {
public:
LoggingStream(raw_ostream &OS) : OS(OS) {}
void applyLocked(llvm::function_ref<void(raw_ostream &OS)> Fn) {
std::unique_lock<std::mutex> LockGuard(Lock);
auto Now = std::chrono::system_clock::now();
OS << Now << ": ";
Fn(OS);
OS.flush();
}
private:
std::mutex Lock;
raw_ostream &OS;
};
// Simple helper to save temporary files for debug.
static void saveTempBitcode(const Module &TheModule, StringRef TempDir,
unsigned count, StringRef Suffix) {
if (TempDir.empty())
return;
// User asked to save temps, let dump the bitcode file after import.
std::string SaveTempPath = (TempDir + llvm::Twine(count) + Suffix).str();
std::error_code EC;
raw_fd_ostream OS(SaveTempPath, EC, sys::fs::OF_None);
if (EC)
report_fatal_error(Twine("Failed to open ") + SaveTempPath +
" to save optimized bitcode\n");
WriteBitcodeToFile(TheModule, OS, /* ShouldPreserveUseListOrder */ true);
}
static const GlobalValueSummary *
getFirstDefinitionForLinker(const GlobalValueSummaryList &GVSummaryList) {
// If there is any strong definition anywhere, get it.
auto StrongDefForLinker = llvm::find_if(
GVSummaryList, [](const std::unique_ptr<GlobalValueSummary> &Summary) {
auto Linkage = Summary->linkage();
return !GlobalValue::isAvailableExternallyLinkage(Linkage) &&
!GlobalValue::isWeakForLinker(Linkage);
});
if (StrongDefForLinker != GVSummaryList.end())
return StrongDefForLinker->get();
// Get the first *linker visible* definition for this global in the summary
// list.
auto FirstDefForLinker = llvm::find_if(
GVSummaryList, [](const std::unique_ptr<GlobalValueSummary> &Summary) {
auto Linkage = Summary->linkage();
return !GlobalValue::isAvailableExternallyLinkage(Linkage);
});
// Extern templates can be emitted as available_externally.
if (FirstDefForLinker == GVSummaryList.end())
return nullptr;
return FirstDefForLinker->get();
}
// Populate map of GUID to the prevailing copy for any multiply defined
// symbols. Currently assume first copy is prevailing, or any strong
// definition. Can be refined with Linker information in the future.
static void computePrevailingCopies(
const ModuleSummaryIndex &Index,
DenseMap<GlobalValue::GUID, const GlobalValueSummary *> &PrevailingCopy) {
auto HasMultipleCopies = [&](const GlobalValueSummaryList &GVSummaryList) {
return GVSummaryList.size() > 1;
};
for (auto &I : Index) {
if (HasMultipleCopies(I.second.SummaryList))
PrevailingCopy[I.first] =
getFirstDefinitionForLinker(I.second.SummaryList);
}
}
static StringMap<lto::InputFile *>
generateModuleMap(std::vector<std::unique_ptr<lto::InputFile>> &Modules) {
StringMap<lto::InputFile *> ModuleMap;
for (auto &M : Modules) {
LLVM_DEBUG(dbgs() << "Adding module " << M->getName() << " to ModuleMap\n");
assert(!ModuleMap.contains(M->getName()) &&
"Expect unique Buffer Identifier");
ModuleMap[M->getName()] = M.get();
}
return ModuleMap;
}
static void promoteModule(Module &TheModule, const ModuleSummaryIndex &Index,
bool ClearDSOLocalOnDeclarations) {
if (renameModuleForThinLTO(TheModule, Index, ClearDSOLocalOnDeclarations))
report_fatal_error("renameModuleForThinLTO failed");
}
namespace {
class ThinLTODiagnosticInfo : public DiagnosticInfo {
const Twine &Msg;
public:
ThinLTODiagnosticInfo(const Twine &DiagMsg,
DiagnosticSeverity Severity = DS_Error)
: DiagnosticInfo(DK_Linker, Severity), Msg(DiagMsg) {}
void print(DiagnosticPrinter &DP) const override { DP << Msg; }
};
}
/// Verify the module and strip broken debug info.
static void verifyLoadedModule(Module &TheModule) {
bool BrokenDebugInfo = false;
if (verifyModule(TheModule, &dbgs(), &BrokenDebugInfo))
report_fatal_error("Broken module found, compilation aborted!");
if (BrokenDebugInfo) {
TheModule.getContext().diagnose(ThinLTODiagnosticInfo(
"Invalid debug info found, debug info will be stripped", DS_Warning));
StripDebugInfo(TheModule);
}
}
static std::unique_ptr<Module> loadModuleFromInput(lto::InputFile *Input,
LLVMContext &Context,
bool Lazy,
bool IsImporting) {
auto &Mod = Input->getSingleBitcodeModule();
SMDiagnostic Err;
Expected<std::unique_ptr<Module>> ModuleOrErr =
Lazy ? Mod.getLazyModule(Context,
/* ShouldLazyLoadMetadata */ true, IsImporting)
: Mod.parseModule(Context);
if (!ModuleOrErr) {
handleAllErrors(ModuleOrErr.takeError(), [&](ErrorInfoBase &EIB) {
SMDiagnostic Err = SMDiagnostic(Mod.getModuleIdentifier(),
SourceMgr::DK_Error, EIB.message());
Err.print("ThinLTO", errs());
});
report_fatal_error("Can't load module, abort.");
}
if (!Lazy)
verifyLoadedModule(*ModuleOrErr.get());
return std::move(*ModuleOrErr);
}
static void
crossImportIntoModule(Module &TheModule, const ModuleSummaryIndex &Index,
StringMap<lto::InputFile *> &ModuleMap,
const FunctionImporter::ImportMapTy &ImportList,
bool ClearDSOLocalOnDeclarations) {
auto Loader = [&](StringRef Identifier) {
auto &Input = ModuleMap[Identifier];
return loadModuleFromInput(Input, TheModule.getContext(),
/*Lazy=*/true, /*IsImporting*/ true);
};
FunctionImporter Importer(Index, Loader, ClearDSOLocalOnDeclarations);
Expected<bool> Result = Importer.importFunctions(TheModule, ImportList);
if (!Result) {
handleAllErrors(Result.takeError(), [&](ErrorInfoBase &EIB) {
SMDiagnostic Err = SMDiagnostic(TheModule.getModuleIdentifier(),
SourceMgr::DK_Error, EIB.message());
Err.print("ThinLTO", errs());
});
report_fatal_error("importFunctions failed");
}
// Verify again after cross-importing.
verifyLoadedModule(TheModule);
}
static void optimizeModule(Module &TheModule, TargetMachine &TM,
unsigned OptLevel, bool Freestanding,
bool DebugPassManager, ModuleSummaryIndex *Index) {
std::optional<PGOOptions> PGOOpt;
LoopAnalysisManager LAM;
FunctionAnalysisManager FAM;
CGSCCAnalysisManager CGAM;
ModuleAnalysisManager MAM;
PassInstrumentationCallbacks PIC;
StandardInstrumentations SI(TheModule.getContext(), DebugPassManager);
SI.registerCallbacks(PIC, &MAM);
PipelineTuningOptions PTO;
PTO.LoopVectorization = true;
PTO.SLPVectorization = true;
PassBuilder PB(&TM, PTO, PGOOpt, &PIC);
std::unique_ptr<TargetLibraryInfoImpl> TLII(
new TargetLibraryInfoImpl(Triple(TM.getTargetTriple())));
if (Freestanding)
TLII->disableAllFunctions();
FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
// Register all the basic analyses with the managers.
PB.registerModuleAnalyses(MAM);
PB.registerCGSCCAnalyses(CGAM);
PB.registerFunctionAnalyses(FAM);
PB.registerLoopAnalyses(LAM);
PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
ModulePassManager MPM;
OptimizationLevel OL;
switch (OptLevel) {
default:
llvm_unreachable("Invalid optimization level");
case 0:
OL = OptimizationLevel::O0;
break;
case 1:
OL = OptimizationLevel::O1;
break;
case 2:
OL = OptimizationLevel::O2;
break;
case 3:
OL = OptimizationLevel::O3;
break;
}
MPM.addPass(PB.buildThinLTODefaultPipeline(OL, Index));
MPM.run(TheModule, MAM);
}
static void
addUsedSymbolToPreservedGUID(const lto::InputFile &File,
DenseSet<GlobalValue::GUID> &PreservedGUID) {
for (const auto &Sym : File.symbols()) {
if (Sym.isUsed())
PreservedGUID.insert(GlobalValue::getGUID(Sym.getIRName()));
}
}
// Convert the PreservedSymbols map from "Name" based to "GUID" based.
static void computeGUIDPreservedSymbols(const lto::InputFile &File,
const StringSet<> &PreservedSymbols,
const Triple &TheTriple,
DenseSet<GlobalValue::GUID> &GUIDs) {
// Iterate the symbols in the input file and if the input has preserved symbol
// compute the GUID for the symbol.
for (const auto &Sym : File.symbols()) {
if (PreservedSymbols.count(Sym.getName()) && !Sym.getIRName().empty())
GUIDs.insert(GlobalValue::getGUID(GlobalValue::getGlobalIdentifier(
Sym.getIRName(), GlobalValue::ExternalLinkage, "")));
}
}
static DenseSet<GlobalValue::GUID>
computeGUIDPreservedSymbols(const lto::InputFile &File,
const StringSet<> &PreservedSymbols,
const Triple &TheTriple) {
DenseSet<GlobalValue::GUID> GUIDPreservedSymbols(PreservedSymbols.size());
computeGUIDPreservedSymbols(File, PreservedSymbols, TheTriple,
GUIDPreservedSymbols);
return GUIDPreservedSymbols;
}
std::unique_ptr<MemoryBuffer> codegenModule(Module &TheModule,
TargetMachine &TM) {
SmallVector<char, 128> OutputBuffer;
// CodeGen
{
raw_svector_ostream OS(OutputBuffer);
legacy::PassManager PM;
// If the bitcode files contain ARC code and were compiled with optimization,
// the ObjCARCContractPass must be run, so do it unconditionally here.
PM.add(createObjCARCContractPass());
// Setup the codegen now.
if (TM.addPassesToEmitFile(PM, OS, nullptr, CodeGenFileType::ObjectFile,
/* DisableVerify */ true))
report_fatal_error("Failed to setup codegen");
// Run codegen now. resulting binary is in OutputBuffer.
PM.run(TheModule);
}
return std::make_unique<SmallVectorMemoryBuffer>(
std::move(OutputBuffer), /*RequiresNullTerminator=*/false);
}
struct NullModuleCacheEntry : ModuleCacheEntry {
std::string getEntryPath() override { return "<null>"; }
ErrorOr<std::unique_ptr<MemoryBuffer>> tryLoadingBuffer() override {
return std::error_code();
}
void write(const MemoryBuffer &OutputBuffer) override {}
};
class FileModuleCacheEntry : public ModuleCacheEntry {
public:
static std::unique_ptr<ModuleCacheEntry> create(StringRef CachePath,
std::string Key) {
if (CachePath.empty())
return std::make_unique<NullModuleCacheEntry>();
return std::make_unique<FileModuleCacheEntry>(CachePath, std::move(Key));
}
// Create a cache entry. This compute a unique hash for the Module considering
// the current list of export/import, and offer an interface to query to
// access the content in the cache.
FileModuleCacheEntry(StringRef CachePath, std::string Key) {
assert(!CachePath.empty());
// This choice of file name allows the cache to be pruned (see pruneCache()
// in include/llvm/Support/CachePruning.h).
sys::path::append(EntryPath, CachePath, "llvmcache-" + Key);
}
std::string getEntryPath() final { return EntryPath.str().str(); }
// Try loading the buffer for this cache entry.
ErrorOr<std::unique_ptr<MemoryBuffer>> tryLoadingBuffer() final {
return MemoryBuffer::getFile(EntryPath);
}
// Cache the Produced object file
void write(const MemoryBuffer &OutputBuffer) final {
if (auto Err = llvm::writeToOutput(
EntryPath, [&OutputBuffer](llvm::raw_ostream &OS) -> llvm::Error {
OS << OutputBuffer.getBuffer();
return llvm::Error::success();
}))
report_fatal_error(llvm::formatv("ThinLTO: Can't write file {0}: {1}",
EntryPath,
toString(std::move(Err)).c_str()));
}
Error writeObject(const MemoryBuffer &OutputBuffer,
StringRef OutputPath) final {
// Clear output file if exists for hard-linking.
sys::fs::remove(OutputPath);
// Hard-link the entry (or copy if hard-link fails).
auto Err = sys::fs::create_hard_link(EntryPath, OutputPath);
if (!Err)
return Error::success();
// Hard linking failed, try to copy.
Err = sys::fs::copy_file(EntryPath, OutputPath);
if (!Err)
return Error::success();
// Copy failed (could be because the CacheEntry was removed from the cache
// in the meantime by another process), fall back and try to write down
// the buffer to the output.
errs() << "remark: can't link or copy from cached entry '" << EntryPath
<< "' to '" << OutputPath << "'\n";
// Fallback to default.
return ModuleCacheEntry::writeObject(OutputBuffer, OutputPath);
}
std::optional<std::unique_ptr<MemoryBuffer>> getMappedBuffer() final {
auto ReloadedBufferOrErr = tryLoadingBuffer();
if (auto EC = ReloadedBufferOrErr.getError()) {
// On error, keep the preexisting buffer and print a diagnostic.
errs() << "remark: can't reload cached file '" << getEntryPath()
<< "': " << EC.message() << "\n";
}
return std::move(*ReloadedBufferOrErr);
}
private:
SmallString<128> EntryPath;
};
struct CancellationToken {
std::atomic<bool> WantsToExit{false};
std::mutex Mutex;
std::condition_variable CondVar;
unsigned ExitBlockers{0};
void requestCancellation() {
WantsToExit = true;
std::unique_lock Lock(Mutex);
CondVar.wait(Lock, [&]() { return ExitBlockers == 0; });
}
[[nodiscard]] auto acquireHandle() {
auto ReleaseHandleOnScopeExit = llvm::make_scope_exit([this]() {
std::unique_lock Lock(Mutex);
--ExitBlockers;
CondVar.notify_one();
});
using RetTy = std::optional<decltype(ReleaseHandleOnScopeExit)>;
if (WantsToExit) {
ReleaseHandleOnScopeExit.release();
return RetTy{};
}
std::unique_lock Lock(Mutex);
++ExitBlockers;
return RetTy{std::move(ReleaseHandleOnScopeExit)};
}
};
static void handleCASError(
Error E, llvm::function_ref<void(llvm::function_ref<void(raw_ostream &OS)>)>
Logger) {
if (!E)
return;
// If strict CAS error, abort.
if (StrictCASErrors)
report_fatal_error(std::move(E));
// Otherwise, log the error message and return error_code.
if (Logger)
Logger([&](raw_ostream &OS) {
OS << "LTO CAS Error: '" << toString(std::move(E)) << "'\n";
});
else
consumeError(std::move(E));
}
static cas::CASID createCASProxyOrAbort(cas::ObjectStore &CAS, StringRef Key) {
// Create the key by inserting cache key (SHA1) into CAS to create an ID for
// the correct context.
// TODO: We can have an alternative hashing function that doesn't need to
// store the key into CAS to get the CacheKey.
auto CASKey = CAS.createProxy(std::nullopt, Key);
if (!CASKey)
report_fatal_error(CASKey.takeError());
return CASKey->getID();
}
// ThinLTOCacheEntry: manage caching for a single Module.
class AsyncModuleCacheEntry {
public:
// Access the path to this entry in the cache.
virtual std::string getEntryPath() = 0;
/// Attempt to asynchronously load the cached buffer and invoke the callback.
/// Cache miss is represented as std::error_code().
virtual void tryLoadingBuffer(
std::function<void(ErrorOr<std::unique_ptr<MemoryBuffer>>)> Cb) = 0;
/// Attempt to asynchronously write the computed buffer and invoke the
/// callback.
virtual void write(const MemoryBuffer &OutputBuffer,
std::function<void()> Cb) = 0;
virtual Error writeObject(const MemoryBuffer &OutputBuffer,
StringRef OutputPath) {
std::error_code Err;
raw_fd_ostream OS(OutputPath, Err, sys::fs::CD_CreateAlways);
if (Err)
return createStringError(Err, Twine("Can't open output '") + OutputPath);
OS << OutputBuffer.getBuffer();
return Error::success();
}
virtual std::optional<std::unique_ptr<MemoryBuffer>> getMappedBuffer() {
return std::nullopt;
}
/// Check whether the loaded and written results of this entry are identical.
/// This is only called when DeterministicCheck is enabled, and after both
/// \c tryLoadingBuffer() and \c write() have finished.
virtual bool areLoadedAndWrittenResultsIdentical() const { return true; }
virtual ~AsyncModuleCacheEntry() {}
};
struct NullAsyncModuleCacheEntry : AsyncModuleCacheEntry {
std::string getEntryPath() override { return "<null>"; }
void tryLoadingBuffer(
std::function<void(ErrorOr<std::unique_ptr<MemoryBuffer>>)> Cb) override {
return Cb(std::error_code());
}
void write(const MemoryBuffer &OutputBuffer,
std::function<void()> Cb) override {
return Cb();
}
};
class CASModuleCacheEntry : public AsyncModuleCacheEntry {
public:
// Create a cache entry. This compute a unique hash for the Module considering
// the current list of export/import, and offer an interface to query to
// access the content in the cache.
CASModuleCacheEntry(
cas::ObjectStore &CAS, cas::ActionCache &Cache, std::string Key,
std::function<void(llvm::function_ref<void(raw_ostream &OS)>)> Logger)
: CAS(CAS), Cache(Cache), ID(createCASProxyOrAbort(CAS, Key)),
Logger(std::move(Logger)) {}
std::string getEntryPath() final {
return ID.toString();
}
void tryLoadingBuffer(
std::function<void(ErrorOr<std::unique_ptr<MemoryBuffer>>)> Cb) final {
auto LookupStart = std::chrono::steady_clock::now();
Cache.getAsync(ID, /*Globally=*/true, [=](auto KeyID) {
if (Logger) {
auto LookupEnd = std::chrono::steady_clock::now();
auto Seconds =
std::chrono::duration<double>(LookupEnd - LookupStart).count();
Logger([&](raw_ostream &OS) {
OS << "LTO cache lookup '" << ID << "' in "
<< llvm::format("%.6fs", Seconds) << "\n";
});
}
std::optional<cas::CASID> MaybeKeyID;
if (auto E = std::move(KeyID).moveInto(MaybeKeyID)) {
handleCASError(std::move(E), Logger);
// If handleCASError didn't abort, treat as miss.
return Cb(std::error_code());
}
if (!MaybeKeyID)
return Cb(std::error_code());
auto LoadStart = std::chrono::steady_clock::now();
CAS.getProxyAsync(*MaybeKeyID, [=](auto MaybeObject) {
if (Logger) {
auto LoadEnd = std::chrono::steady_clock::now();
auto Seconds =
std::chrono::duration<double>(LoadEnd - LoadStart).count();
Logger([&](raw_ostream &OS) {
OS << "LTO cache load '" << ID << "' in "
<< llvm::format("%.6fs", Seconds) << "\n";
});
}
if (!MaybeObject) {
handleCASError(MaybeObject.takeError(), Logger);
// If handleCASError didn't abort, treat as miss.
return Cb(std::error_code());
}
return Cb((*MaybeObject)->getMemoryBuffer("", /*NullTerminated=*/true));
});
});
}
void write(const MemoryBuffer &OutputBuffer, std::function<void()> Cb) final {
std::optional<cas::ObjectProxy> Proxy;
if (Error E =
CAS.createProxy({}, OutputBuffer.getBuffer()).moveInto(Proxy)) {
handleCASError(std::move(E), Logger);
return Cb();
}
auto UpdateStart = std::chrono::steady_clock::now();
Cache.putAsync(ID, Proxy->getID(), /*Globally=*/true, [=](auto Err) {
if (Logger) {
auto UpdateEnd = std::chrono::steady_clock::now();
auto Seconds =
std::chrono::duration<double>(UpdateEnd - UpdateStart).count();
Logger([&](raw_ostream &OS) {
OS << "LTO cache update '" << ID << "' in "
<< llvm::format("%.6fs", Seconds) << "\n";
});
}
if (Err)
report_fatal_error(std::move(Err));
Cb();
});
}
private:
cas::ObjectStore &CAS;
cas::ActionCache &Cache;
cas::CASID ID;
std::function<void(llvm::function_ref<void(raw_ostream &OS)>)> Logger;
};
class RemoteModuleCacheEntry : public AsyncModuleCacheEntry {
public:
// Create a cache entry. This compute a unique hash for the Module considering
// the current list of export/import, and offer an interface to query to
// access the content in the cache.
RemoteModuleCacheEntry(
std::shared_ptr<CancellationToken> GetCancelTok,
std::shared_ptr<CancellationToken> PutCancelTok,
cas::remote::ClientServices &Service,
StringRef OutputPath, std::string Key,
std::function<void(llvm::function_ref<void(raw_ostream &OS)>)> Logger)
: GetCancelTok(GetCancelTok), PutCancelTok(PutCancelTok), Service(Service), ID(std::move(Key)),
OutputPath(OutputPath.str()), Logger(std::move(Logger)) {}
std::string getEntryPath() final { return ID; }
void tryLoadingBuffer(
std::function<void(ErrorOr<std::unique_ptr<MemoryBuffer>>)> Cb) final {
auto LookupStart = std::chrono::steady_clock::now();
Service.KVDB->getValueAsync(ID, [=, GetCancelTok = GetCancelTok](auto ErrOrGetResponse) {
auto CancelTokHandle = GetCancelTok->acquireHandle();
if (!CancelTokHandle) {
(void)expectedToOptional(std::move(ErrOrGetResponse));
return;
}
if (Logger) {
auto LookupEnd = std::chrono::steady_clock::now();
auto Seconds =
std::chrono::duration<double>(LookupEnd - LookupStart).count();
Logger([&](raw_ostream &OS) {
OS << "LTO cache lookup '" << ID << "' in "
<< llvm::format("%.6fs", Seconds) << "\n";
});
}
// Use the KVDB to map the ThinLTO key onto the CAS ID.
std::optional<cas::remote::KeyValueDBClient::ValueTy> GetResponse;
if (Error E = std::move(ErrOrGetResponse).moveInto(GetResponse)) {
handleCASError(std::move(E), Logger);
// If handleCASError didn't abort, treat as miss.
return Cb(std::error_code());
}
// Cache Miss.
if (!GetResponse)
return Cb(std::error_code());
// Malformed output. Error.
auto Result = GetResponse->find("Output");
if (Result == GetResponse->end())
return Cb(std::make_error_code(std::errc::message_size));
LoadedCASID = Result->getValue();
std::string TmpPath = OutputPath + ".downloaded.tmp";
// Request the output buffer.
auto LoadStart = std::chrono::steady_clock::now();
Service.CASDB->loadAsync(
*LoadedCASID, TmpPath, [=, GetCancelTok = GetCancelTok](auto LoadResponse) {
auto CancelTokHandle = GetCancelTok->acquireHandle();
if (!CancelTokHandle) {
(void)expectedToOptional(std::move(LoadResponse));
return;
}
if (Logger) {
auto LoadEnd = std::chrono::steady_clock::now();
auto Seconds =
std::chrono::duration<double>(LoadEnd - LoadStart).count();
Logger([&](raw_ostream &OS) {
OS << "LTO cache load '" << ID << "' in "
<< llvm::format("%.6fs", Seconds) << "\n";
});
}
if (!LoadResponse) {
handleCASError(LoadResponse.takeError(), Logger);
// If handleCASError didn't abort, treat as miss.
return Cb(std::error_code());
}
// Object not found. Treat it as a miss.
if (LoadResponse->KeyNotFound)
return Cb(std::error_code());
sys::fs::rename(TmpPath, OutputPath);
// Note: This might pick up the file created by rename in \c
// write().
return Cb(MemoryBuffer::getFile(OutputPath));
});
});
}
Error writeObject(const MemoryBuffer &OutputBuffer,
StringRef OutputPath) final {
std::string TmpPath = this->OutputPath + ".computed.tmp";
if (Error E = AsyncModuleCacheEntry::writeObject(OutputBuffer, TmpPath))
return E;
if (auto EC = sys::fs::rename(TmpPath, OutputPath)) {
(void)sys::fs::remove(TmpPath); // Attempt to clean up.
return createStringError(
EC, "renaming of computed module object file failed");
}
return Error::success();
}
void write(const MemoryBuffer &OutputBuffer, std::function<void()> Cb) final {
std::string TmpPath = OutputPath + ".uploaded.tmp";
if (Error E = AsyncModuleCacheEntry::writeObject(OutputBuffer, TmpPath)) {
handleCASError(std::move(E), Logger);
return;
}
auto SaveStart = std::chrono::steady_clock::now();
// FIXME: Consider passing the buffer contents this in a string instead of file.
Service.CASDB->saveFileAsync(TmpPath, [=, PutCancelTok = PutCancelTok](auto MaybeWrittenCASID) {
sys::fs::remove(TmpPath);
auto CancelTokHandle = PutCancelTok->acquireHandle();
if (!CancelTokHandle) {
(void)expectedToOptional(std::move(MaybeWrittenCASID));
return;
}
if (Logger) {
auto SaveEnd = std::chrono::steady_clock::now();
auto Seconds =
std::chrono::duration<double>(SaveEnd - SaveStart).count();
Logger([&](raw_ostream &OS) {
OS << "LTO cache save '" << ID << "' in "
<< llvm::format("%.6fs", Seconds) << "\n";
});
}
if (Error E = std::move(MaybeWrittenCASID).moveInto(WrittenCASID)) {
handleCASError(std::move(E), Logger);
return Cb();
}
cas::remote::KeyValueDBClient::ValueTy CompResult;
CompResult["Output"] = *WrittenCASID;
auto UpdateStart = std::chrono::steady_clock::now();
Service.KVDB->putValueAsync(ID, CompResult, [=, PutCancelTok = PutCancelTok](auto Err) {
auto CancelTokHandle = PutCancelTok->acquireHandle();
if (!CancelTokHandle) {
(void)consumeError(std::move(Err));
return;
}
if (Logger) {
auto UpdateEnd = std::chrono::steady_clock::now();
auto Seconds =
std::chrono::duration<double>(UpdateEnd - UpdateStart).count();
Logger([&](raw_ostream &OS) {
OS << "LTO cache update '" << ID << "' in "
<< llvm::format("%.6fs", Seconds) << "\n";
});
}
if (Err)
handleCASError(std::move(Err), Logger);
return Cb();
});
});
}
bool areLoadedAndWrittenResultsIdentical() const override {
if (LoadedCASID && WrittenCASID && *LoadedCASID != *WrittenCASID) {
Error E = createStringError(
inconvertibleErrorCode(),
"ThinLTO deterministic check failed: " + *LoadedCASID +
" (expected) vs. " + *WrittenCASID + " (actual)");
handleCASError(std::move(E), Logger);
return false;
}
return true;
}
private:
std::shared_ptr<CancellationToken> GetCancelTok;
std::shared_ptr<CancellationToken> PutCancelTok;
cas::remote::ClientServices &Service;
std::string ID;
std::string OutputPath;
std::optional<std::string> LoadedCASID;
std::optional<std::string> WrittenCASID;
std::function<void(llvm::function_ref<void(raw_ostream &OS)>)> Logger;
};
static std::unique_ptr<MemoryBuffer>
ProcessThinLTOModule(Module &TheModule, ModuleSummaryIndex &Index,
StringMap<lto::InputFile *> &ModuleMap, TargetMachine &TM,
const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,
const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
const GVSummaryMapTy &DefinedGlobals,
const ThinLTOCodeGenerator::CachingOptions &CacheOptions,
bool DisableCodeGen, StringRef SaveTempsDir,
bool Freestanding, unsigned OptLevel, unsigned count,
bool DebugPassManager) {
// "Benchmark"-like optimization: single-source case
bool SingleModule = (ModuleMap.size() == 1);
// When linking an ELF shared object, dso_local should be dropped. We
// conservatively do this for -fpic.
bool ClearDSOLocalOnDeclarations =
TM.getTargetTriple().isOSBinFormatELF() &&
TM.getRelocationModel() != Reloc::Static &&
TheModule.getPIELevel() == PIELevel::Default;
if (!SingleModule) {
promoteModule(TheModule, Index, ClearDSOLocalOnDeclarations);
// Apply summary-based prevailing-symbol resolution decisions.
thinLTOFinalizeInModule(TheModule, DefinedGlobals, /*PropagateAttrs=*/true);
// Save temps: after promotion.
saveTempBitcode(TheModule, SaveTempsDir, count, ".1.promoted.bc");
}
// Be friendly and don't nuke totally the module when the client didn't
// supply anything to preserve.
if (!ExportList.empty() || !GUIDPreservedSymbols.empty()) {
// Apply summary-based internalization decisions.
thinLTOInternalizeModule(TheModule, DefinedGlobals);
}
// Save internalized bitcode
saveTempBitcode(TheModule, SaveTempsDir, count, ".2.internalized.bc");
if (!SingleModule)
crossImportIntoModule(TheModule, Index, ModuleMap, ImportList,
ClearDSOLocalOnDeclarations);
// Do this after any importing so that imported code is updated.
// See comment at call to updateVCallVisibilityInIndex() for why
// WholeProgramVisibilityEnabledInLTO is false.
updatePublicTypeTestCalls(TheModule,
/* WholeProgramVisibilityEnabledInLTO */ false);
// Save temps: after cross-module import.
saveTempBitcode(TheModule, SaveTempsDir, count, ".3.imported.bc");
optimizeModule(TheModule, TM, OptLevel, Freestanding, DebugPassManager,
&Index);
saveTempBitcode(TheModule, SaveTempsDir, count, ".4.opt.bc");
if (DisableCodeGen) {
// Configured to stop before CodeGen, serialize the bitcode and return.
SmallVector<char, 128> OutputBuffer;
{
raw_svector_ostream OS(OutputBuffer);
ProfileSummaryInfo PSI(TheModule);
auto Index = buildModuleSummaryIndex(TheModule, nullptr, &PSI);
WriteBitcodeToFile(TheModule, OS, true, &Index);
}
return std::make_unique<SmallVectorMemoryBuffer>(
std::move(OutputBuffer), /*RequiresNullTerminator=*/false);
}
return codegenModule(TheModule, TM);
}
/// Resolve prevailing symbols. Record resolutions in the \p ResolvedODR map
/// for caching, and in the \p Index for application during the ThinLTO
/// backends. This is needed for correctness for exported symbols (ensure
/// at least one copy kept) and a compile-time optimization (to drop duplicate
/// copies when possible).
static void resolvePrevailingInIndex(
ModuleSummaryIndex &Index,
StringMap<std::map<GlobalValue::GUID, GlobalValue::LinkageTypes>>
&ResolvedODR,
const DenseSet<GlobalValue::GUID> &GUIDPreservedSymbols,
const DenseMap<GlobalValue::GUID, const GlobalValueSummary *>
&PrevailingCopy) {
auto isPrevailing = [&](GlobalValue::GUID GUID, const GlobalValueSummary *S) {
const auto &Prevailing = PrevailingCopy.find(GUID);
// Not in map means that there was only one copy, which must be prevailing.
if (Prevailing == PrevailingCopy.end())
return true;
return Prevailing->second == S;
};
auto recordNewLinkage = [&](StringRef ModuleIdentifier,
GlobalValue::GUID GUID,
GlobalValue::LinkageTypes NewLinkage) {
ResolvedODR[ModuleIdentifier][GUID] = NewLinkage;
};
// TODO Conf.VisibilityScheme can be lto::Config::ELF for ELF.
lto::Config Conf;
thinLTOResolvePrevailingInIndex(Conf, Index, isPrevailing, recordNewLinkage,
GUIDPreservedSymbols);
}
// Initialize the TargetMachine builder for a given Triple
static void initTMBuilder(TargetMachineBuilder &TMBuilder,
const Triple &TheTriple) {
if (TMBuilder.MCpu.empty())
TMBuilder.MCpu = lto::getThinLTODefaultCPU(TheTriple);
TMBuilder.TheTriple = std::move(TheTriple);
}
} // end anonymous namespace
std::optional<std::string> ModuleCacheEntry::computeCacheKey(
const ModuleSummaryIndex &Index, StringRef ModuleID,
const FunctionImporter::ImportMapTy &ImportList,
const FunctionImporter::ExportSetTy &ExportList,