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//===- LTO.cpp ------------------------------------------------------------===//
//
// The LLVM Linker
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
#include "LTO.h"
#include "Config.h"
#include "Error.h"
#include "InputFiles.h"
#include "Symbols.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/Linker/IRMover.h"
#include "llvm/Support/StringSaver.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
using namespace llvm;
using namespace llvm::object;
using namespace llvm::ELF;
using namespace lld;
using namespace lld::elf;
// This is for use when debugging LTO.
static void saveLtoObjectFile(StringRef Buffer) {
std::error_code EC;
raw_fd_ostream OS(Config->OutputFile.str() + ".lto.o", EC,
sys::fs::OpenFlags::F_None);
check(EC);
OS << Buffer;
}
// This is for use when debugging LTO.
static void saveBCFile(Module &M, StringRef Suffix) {
std::error_code EC;
raw_fd_ostream OS(Config->OutputFile.str() + Suffix.str(), EC,
sys::fs::OpenFlags::F_None);
check(EC);
WriteBitcodeToFile(&M, OS, /* ShouldPreserveUseListOrder */ true);
}
// Run LTO passes.
// FIXME: Reduce code duplication by sharing this code with the gold plugin.
static void runLTOPasses(Module &M, TargetMachine &TM) {
legacy::PassManager LtoPasses;
LtoPasses.add(createTargetTransformInfoWrapperPass(TM.getTargetIRAnalysis()));
PassManagerBuilder PMB;
PMB.LibraryInfo = new TargetLibraryInfoImpl(Triple(TM.getTargetTriple()));
PMB.Inliner = createFunctionInliningPass();
PMB.VerifyInput = true;
PMB.VerifyOutput = true;
PMB.LoopVectorize = true;
PMB.SLPVectorize = true;
PMB.OptLevel = 2; // FIXME: This should be an option.
PMB.populateLTOPassManager(LtoPasses);
LtoPasses.run(M);
if (Config->SaveTemps)
saveBCFile(M, ".lto.opt.bc");
}
void BitcodeCompiler::add(BitcodeFile &F) {
std::unique_ptr<IRObjectFile> Obj =
check(IRObjectFile::create(F.MB, Context));
std::vector<GlobalValue *> Keep;
unsigned BodyIndex = 0;
ArrayRef<SymbolBody *> Bodies = F.getSymbols();
for (const BasicSymbolRef &Sym : Obj->symbols()) {
GlobalValue *GV = Obj->getSymbolGV(Sym.getRawDataRefImpl());
assert(GV);
if (GV->hasAppendingLinkage()) {
Keep.push_back(GV);
continue;
}
if (!BitcodeFile::shouldSkip(Sym)) {
if (SymbolBody *B = Bodies[BodyIndex++])
if (&B->repl() == B && isa<DefinedBitcode>(B)) {
switch (GV->getLinkage()) {
default:
break;
case llvm::GlobalValue::LinkOnceAnyLinkage:
GV->setLinkage(GlobalValue::WeakAnyLinkage);
break;
case llvm::GlobalValue::LinkOnceODRLinkage:
GV->setLinkage(GlobalValue::WeakODRLinkage);
break;
}
Keep.push_back(GV);
}
}
}
Mover.move(Obj->takeModule(), Keep,
[](GlobalValue &, IRMover::ValueAdder) {});
}
// Merge all the bitcode files we have seen, codegen the result
// and return the resulting ObjectFile.
template <class ELFT>
std::unique_ptr<elf::ObjectFile<ELFT>> BitcodeCompiler::compile() {
if (Config->SaveTemps)
saveBCFile(Combined, ".lto.bc");
std::unique_ptr<TargetMachine> TM(getTargetMachine());
runLTOPasses(Combined, *TM);
raw_svector_ostream OS(OwningData);
legacy::PassManager CodeGenPasses;
if (TM->addPassesToEmitFile(CodeGenPasses, OS,
TargetMachine::CGFT_ObjectFile))
fatal("failed to setup codegen");
CodeGenPasses.run(Combined);
MB = MemoryBuffer::getMemBuffer(OwningData,
"LLD-INTERNAL-combined-lto-object", false);
if (Config->SaveTemps)
saveLtoObjectFile(MB->getBuffer());
std::unique_ptr<InputFile> IF = createObjectFile(*MB);
auto *OF = cast<ObjectFile<ELFT>>(IF.release());
return std::unique_ptr<ObjectFile<ELFT>>(OF);
}
TargetMachine *BitcodeCompiler::getTargetMachine() {
StringRef TripleStr = Combined.getTargetTriple();
std::string Msg;
const Target *T = TargetRegistry::lookupTarget(TripleStr, Msg);
if (!T)
fatal("target not found: " + Msg);
TargetOptions Options;
Reloc::Model R = Config->Pic ? Reloc::PIC_ : Reloc::Static;
return T->createTargetMachine(TripleStr, "", "", Options, R);
}
template std::unique_ptr<elf::ObjectFile<ELF32LE>> BitcodeCompiler::compile();
template std::unique_ptr<elf::ObjectFile<ELF32BE>> BitcodeCompiler::compile();
template std::unique_ptr<elf::ObjectFile<ELF64LE>> BitcodeCompiler::compile();
template std::unique_ptr<elf::ObjectFile<ELF64BE>> BitcodeCompiler::compile();
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