forked from OSchip/llvm-project
170 lines
5.6 KiB
C++
170 lines
5.6 KiB
C++
//===- LTO.cpp ------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "LTO.h"
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#include "Config.h"
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#include "InputFiles.h"
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#include "Symbols.h"
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#include "lld/Common/Args.h"
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#include "lld/Common/ErrorHandler.h"
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#include "lld/Common/Strings.h"
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#include "lld/Common/TargetOptionsCommandFlags.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/ADT/Twine.h"
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#include "llvm/IR/DiagnosticPrinter.h"
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#include "llvm/LTO/Config.h"
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#include "llvm/LTO/LTO.h"
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#include "llvm/Object/SymbolicFile.h"
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#include "llvm/Support/Caching.h"
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#include "llvm/Support/CodeGen.h"
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#include "llvm/Support/Error.h"
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#include "llvm/Support/FileSystem.h"
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#include "llvm/Support/MemoryBuffer.h"
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#include "llvm/Support/raw_ostream.h"
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#include <algorithm>
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#include <cstddef>
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#include <memory>
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#include <string>
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#include <system_error>
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#include <vector>
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using namespace llvm;
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namespace lld {
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namespace wasm {
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static std::unique_ptr<lto::LTO> createLTO() {
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lto::Config c;
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c.Options = initTargetOptionsFromCodeGenFlags();
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// Always emit a section per function/data with LTO.
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c.Options.FunctionSections = true;
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c.Options.DataSections = true;
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c.DisableVerify = config->disableVerify;
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c.DiagHandler = diagnosticHandler;
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c.OptLevel = config->ltoo;
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c.MAttrs = getMAttrs();
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c.CGOptLevel = args::getCGOptLevel(config->ltoo);
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c.UseNewPM = config->ltoNewPassManager;
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c.DebugPassManager = config->ltoDebugPassManager;
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if (config->relocatable)
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c.RelocModel = None;
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else if (config->isPic)
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c.RelocModel = Reloc::PIC_;
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else
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c.RelocModel = Reloc::Static;
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if (config->saveTemps)
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checkError(c.addSaveTemps(config->outputFile.str() + ".",
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/*UseInputModulePath*/ true));
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lto::ThinBackend backend = lto::createInProcessThinBackend(
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llvm::heavyweight_hardware_concurrency(config->thinLTOJobs));
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return std::make_unique<lto::LTO>(std::move(c), backend,
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config->ltoPartitions);
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}
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BitcodeCompiler::BitcodeCompiler() : ltoObj(createLTO()) {}
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BitcodeCompiler::~BitcodeCompiler() = default;
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static void undefine(Symbol *s) {
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if (auto f = dyn_cast<DefinedFunction>(s))
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replaceSymbol<UndefinedFunction>(f, f->getName(), None, None, 0,
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f->getFile(), f->signature);
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else if (isa<DefinedData>(s))
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replaceSymbol<UndefinedData>(s, s->getName(), 0, s->getFile());
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else
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llvm_unreachable("unexpected symbol kind");
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}
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void BitcodeCompiler::add(BitcodeFile &f) {
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lto::InputFile &obj = *f.obj;
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unsigned symNum = 0;
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ArrayRef<Symbol *> syms = f.getSymbols();
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std::vector<lto::SymbolResolution> resols(syms.size());
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// Provide a resolution to the LTO API for each symbol.
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for (const lto::InputFile::Symbol &objSym : obj.symbols()) {
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Symbol *sym = syms[symNum];
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lto::SymbolResolution &r = resols[symNum];
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++symNum;
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// Ideally we shouldn't check for SF_Undefined but currently IRObjectFile
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// reports two symbols for module ASM defined. Without this check, lld
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// flags an undefined in IR with a definition in ASM as prevailing.
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// Once IRObjectFile is fixed to report only one symbol this hack can
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// be removed.
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r.Prevailing = !objSym.isUndefined() && sym->getFile() == &f;
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r.VisibleToRegularObj = config->relocatable || sym->isUsedInRegularObj ||
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sym->isNoStrip() ||
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(r.Prevailing && sym->isExported());
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if (r.Prevailing)
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undefine(sym);
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// We tell LTO to not apply interprocedural optimization for wrapped
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// (with --wrap) symbols because otherwise LTO would inline them while
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// their values are still not final.
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r.LinkerRedefined = !sym->canInline;
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}
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checkError(ltoObj->add(std::move(f.obj), resols));
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}
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// Merge all the bitcode files we have seen, codegen the result
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// and return the resulting objects.
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std::vector<StringRef> BitcodeCompiler::compile() {
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unsigned maxTasks = ltoObj->getMaxTasks();
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buf.resize(maxTasks);
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files.resize(maxTasks);
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// The --thinlto-cache-dir option specifies the path to a directory in which
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// to cache native object files for ThinLTO incremental builds. If a path was
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// specified, configure LTO to use it as the cache directory.
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NativeObjectCache cache;
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if (!config->thinLTOCacheDir.empty())
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cache =
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check(localCache("ThinLTO", "Thin", config->thinLTOCacheDir,
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[&](size_t task, std::unique_ptr<MemoryBuffer> mb) {
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files[task] = std::move(mb);
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}));
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checkError(ltoObj->run(
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[&](size_t task) {
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return std::make_unique<NativeObjectStream>(
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std::make_unique<raw_svector_ostream>(buf[task]));
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},
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cache));
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if (!config->thinLTOCacheDir.empty())
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pruneCache(config->thinLTOCacheDir, config->thinLTOCachePolicy);
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std::vector<StringRef> ret;
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for (unsigned i = 0; i != maxTasks; ++i) {
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if (buf[i].empty())
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continue;
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if (config->saveTemps) {
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if (i == 0)
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saveBuffer(buf[i], config->outputFile + ".lto.o");
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else
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saveBuffer(buf[i], config->outputFile + Twine(i) + ".lto.o");
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}
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ret.emplace_back(buf[i].data(), buf[i].size());
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}
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for (std::unique_ptr<MemoryBuffer> &file : files)
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if (file)
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ret.push_back(file->getBuffer());
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return ret;
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}
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} // namespace wasm
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} // namespace lld
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