llvm-6502/tools/lto/lto.cpp
Devang Patel 54959d6cf6 Now LICM is a LoopPass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35001 91177308-0d34-0410-b5e6-96231b3b80d8
2007-03-07 04:41:30 +00:00

497 lines
16 KiB
C++

//===-lto.cpp - LLVM Link Time Optimizer ----------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by Devang Patel and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the Link Time Optimization library. This library is
// intended to be used by linker to optimize code at link time.
//
//===----------------------------------------------------------------------===//
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Linker.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Bytecode/Reader.h"
#include "llvm/Bytecode/Writer.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/FileUtilities.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/Mangler.h"
#include "llvm/System/Program.h"
#include "llvm/System/Signals.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/CodeGen/FileWriters.h"
#include "llvm/Target/SubtargetFeature.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetMachineRegistry.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Analysis/LoadValueNumbering.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Streams.h"
#include "llvm/LinkTimeOptimizer.h"
#include <fstream>
#include <ostream>
using namespace llvm;
extern "C"
llvm::LinkTimeOptimizer *createLLVMOptimizer()
{
llvm::LTO *l = new llvm::LTO();
return l;
}
/// If symbol is not used then make it internal and let optimizer takes
/// care of it.
void LLVMSymbol::mayBeNotUsed() {
gv->setLinkage(GlobalValue::InternalLinkage);
}
// Map LLVM LinkageType to LTO LinakgeType
static LTOLinkageTypes
getLTOLinkageType(GlobalValue *v)
{
LTOLinkageTypes lt;
if (v->hasExternalLinkage())
lt = LTOExternalLinkage;
else if (v->hasLinkOnceLinkage())
lt = LTOLinkOnceLinkage;
else if (v->hasWeakLinkage())
lt = LTOWeakLinkage;
else
// Otherwise it is internal linkage for link time optimizer
lt = LTOInternalLinkage;
return lt;
}
// Find exeternal symbols referenced by VALUE. This is a recursive function.
static void
findExternalRefs(Value *value, std::set<std::string> &references,
Mangler &mangler) {
if (GlobalValue *gv = dyn_cast<GlobalValue>(value)) {
LTOLinkageTypes lt = getLTOLinkageType(gv);
if (lt != LTOInternalLinkage && strncmp (gv->getName().c_str(), "llvm.", 5))
references.insert(mangler.getValueName(gv));
}
// GlobalValue, even with InternalLinkage type, may have operands with
// ExternalLinkage type. Do not ignore these operands.
if (Constant *c = dyn_cast<Constant>(value))
// Handle ConstantExpr, ConstantStruct, ConstantArry etc..
for (unsigned i = 0, e = c->getNumOperands(); i != e; ++i)
findExternalRefs(c->getOperand(i), references, mangler);
}
/// If Module with InputFilename is available then remove it from allModules
/// and call delete on it.
void
LTO::removeModule (const std::string &InputFilename)
{
NameToModuleMap::iterator pos = allModules.find(InputFilename.c_str());
if (pos == allModules.end())
return;
Module *m = pos->second;
allModules.erase(pos);
delete m;
}
/// InputFilename is a LLVM bytecode file. If Module with InputFilename is
/// available then return it. Otherwise parseInputFilename.
Module *
LTO::getModule(const std::string &InputFilename)
{
Module *m = NULL;
NameToModuleMap::iterator pos = allModules.find(InputFilename.c_str());
if (pos != allModules.end())
m = allModules[InputFilename.c_str()];
else {
m = ParseBytecodeFile(InputFilename);
allModules[InputFilename.c_str()] = m;
}
return m;
}
/// InputFilename is a LLVM bytecode file. Reade this bytecode file and
/// set corresponding target triplet string.
void
LTO::getTargetTriple(const std::string &InputFilename,
std::string &targetTriple)
{
Module *m = getModule(InputFilename);
if (m)
targetTriple = m->getTargetTriple();
}
/// InputFilename is a LLVM bytecode file. Read it using bytecode reader.
/// Collect global functions and symbol names in symbols vector.
/// Collect external references in references vector.
/// Return LTO_READ_SUCCESS if there is no error.
enum LTOStatus
LTO::readLLVMObjectFile(const std::string &InputFilename,
NameToSymbolMap &symbols,
std::set<std::string> &references)
{
Module *m = getModule(InputFilename);
if (!m)
return LTO_READ_FAILURE;
// Collect Target info
getTarget(m);
if (!Target)
return LTO_READ_FAILURE;
// Use mangler to add GlobalPrefix to names to match linker names.
// FIXME : Instead of hard coding "-" use GlobalPrefix.
Mangler mangler(*m, Target->getTargetAsmInfo()->getGlobalPrefix());
modules.push_back(m);
for (Module::iterator f = m->begin(), e = m->end(); f != e; ++f) {
LTOLinkageTypes lt = getLTOLinkageType(f);
if (!f->isDeclaration() && lt != LTOInternalLinkage
&& strncmp (f->getName().c_str(), "llvm.", 5)) {
int alignment = ( 16 > f->getAlignment() ? 16 : f->getAlignment());
LLVMSymbol *newSymbol = new LLVMSymbol(lt, f, f->getName(),
mangler.getValueName(f),
Log2_32(alignment));
symbols[newSymbol->getMangledName()] = newSymbol;
allSymbols[newSymbol->getMangledName()] = newSymbol;
}
// Collect external symbols referenced by this function.
for (Function::iterator b = f->begin(), fe = f->end(); b != fe; ++b)
for (BasicBlock::iterator i = b->begin(), be = b->end();
i != be; ++i)
for (unsigned count = 0, total = i->getNumOperands();
count != total; ++count)
findExternalRefs(i->getOperand(count), references, mangler);
}
for (Module::global_iterator v = m->global_begin(), e = m->global_end();
v != e; ++v) {
LTOLinkageTypes lt = getLTOLinkageType(v);
if (!v->isDeclaration() && lt != LTOInternalLinkage
&& strncmp (v->getName().c_str(), "llvm.", 5)) {
const TargetData *TD = Target->getTargetData();
LLVMSymbol *newSymbol = new LLVMSymbol(lt, v, v->getName(),
mangler.getValueName(v),
TD->getPreferredAlignmentLog(v));
symbols[newSymbol->getMangledName()] = newSymbol;
allSymbols[newSymbol->getMangledName()] = newSymbol;
for (unsigned count = 0, total = v->getNumOperands();
count != total; ++count)
findExternalRefs(v->getOperand(count), references, mangler);
}
}
return LTO_READ_SUCCESS;
}
/// Get TargetMachine.
/// Use module M to find appropriate Target.
void
LTO::getTarget (Module *M) {
if (Target)
return;
std::string Err;
const TargetMachineRegistry::Entry* March =
TargetMachineRegistry::getClosestStaticTargetForModule(*M, Err);
if (March == 0)
return;
// Create target
std::string Features;
Target = March->CtorFn(*M, Features);
}
/// Optimize module M using various IPO passes. Use exportList to
/// internalize selected symbols. Target platform is selected
/// based on information available to module M. No new target
/// features are selected.
enum LTOStatus
LTO::optimize(Module *M, std::ostream &Out,
std::vector<const char *> &exportList)
{
// Instantiate the pass manager to organize the passes.
PassManager Passes;
// Collect Target info
getTarget(M);
if (!Target)
return LTO_NO_TARGET;
// Start off with a verification pass.
Passes.add(createVerifierPass());
// Add an appropriate TargetData instance for this module...
Passes.add(new TargetData(*Target->getTargetData()));
// Internalize symbols if export list is nonemty
if (!exportList.empty())
Passes.add(createInternalizePass(exportList));
// Now that we internalized some globals, see if we can hack on them!
Passes.add(createGlobalOptimizerPass());
// Linking modules together can lead to duplicated global constants, only
// keep one copy of each constant...
Passes.add(createConstantMergePass());
// If the -s command line option was specified, strip the symbols out of the
// resulting program to make it smaller. -s is a GLD option that we are
// supporting.
Passes.add(createStripSymbolsPass());
// Propagate constants at call sites into the functions they call.
Passes.add(createIPConstantPropagationPass());
// Remove unused arguments from functions...
Passes.add(createDeadArgEliminationPass());
Passes.add(createFunctionInliningPass()); // Inline small functions
Passes.add(createPruneEHPass()); // Remove dead EH info
Passes.add(createGlobalDCEPass()); // Remove dead functions
// If we didn't decide to inline a function, check to see if we can
// transform it to pass arguments by value instead of by reference.
Passes.add(createArgumentPromotionPass());
// The IPO passes may leave cruft around. Clean up after them.
Passes.add(createInstructionCombiningPass());
Passes.add(createScalarReplAggregatesPass()); // Break up allocas
// Run a few AA driven optimizations here and now, to cleanup the code.
Passes.add(createGlobalsModRefPass()); // IP alias analysis
Passes.add(createLICMPass()); // Hoist loop invariants
Passes.add(createLoadValueNumberingPass()); // GVN for load instrs
Passes.add(createGCSEPass()); // Remove common subexprs
Passes.add(createDeadStoreEliminationPass()); // Nuke dead stores
// Cleanup and simplify the code after the scalar optimizations.
Passes.add(createInstructionCombiningPass());
// Delete basic blocks, which optimization passes may have killed...
Passes.add(createCFGSimplificationPass());
// Now that we have optimized the program, discard unreachable functions...
Passes.add(createGlobalDCEPass());
// Make sure everything is still good.
Passes.add(createVerifierPass());
FunctionPassManager *CodeGenPasses =
new FunctionPassManager(new ExistingModuleProvider(M));
CodeGenPasses->add(new TargetData(*Target->getTargetData()));
MachineCodeEmitter *MCE = 0;
switch (Target->addPassesToEmitFile(*CodeGenPasses, Out,
TargetMachine::AssemblyFile, true)) {
default:
case FileModel::Error:
return LTO_WRITE_FAILURE;
case FileModel::AsmFile:
break;
case FileModel::MachOFile:
MCE = AddMachOWriter(*CodeGenPasses, Out, *Target);
break;
case FileModel::ElfFile:
MCE = AddELFWriter(*CodeGenPasses, Out, *Target);
break;
}
if (Target->addPassesToEmitFileFinish(*CodeGenPasses, MCE, true))
return LTO_WRITE_FAILURE;
// Run our queue of passes all at once now, efficiently.
Passes.run(*M);
// Run the code generator, if present.
CodeGenPasses->doInitialization();
for (Module::iterator I = M->begin(), E = M->end(); I != E; ++I) {
if (!I->isDeclaration())
CodeGenPasses->run(*I);
}
CodeGenPasses->doFinalization();
return LTO_OPT_SUCCESS;
}
///Link all modules together and optimize them using IPO. Generate
/// native object file using OutputFilename
/// Return appropriate LTOStatus.
enum LTOStatus
LTO::optimizeModules(const std::string &OutputFilename,
std::vector<const char *> &exportList,
std::string &targetTriple,
bool saveTemps,
const char *FinalOutputFilename)
{
if (modules.empty())
return LTO_NO_WORK;
std::ios::openmode io_mode =
std::ios::out | std::ios::trunc | std::ios::binary;
std::string *errMsg = NULL;
Module *bigOne = modules[0];
Linker theLinker("LinkTimeOptimizer", bigOne, false);
for (unsigned i = 1, e = modules.size(); i != e; ++i)
if (theLinker.LinkModules(bigOne, modules[i], errMsg))
return LTO_MODULE_MERGE_FAILURE;
// all modules have been handed off to the linker.
modules.clear();
sys::Path FinalOutputPath(FinalOutputFilename);
FinalOutputPath.eraseSuffix();
if (saveTemps) {
std::string tempFileName(FinalOutputPath.c_str());
tempFileName += "0.bc";
std::ofstream Out(tempFileName.c_str(), io_mode);
OStream L(Out);
WriteBytecodeToFile(bigOne, L);
}
// Strip leading underscore because it was added to match names
// seen by linker.
for (unsigned i = 0, e = exportList.size(); i != e; ++i) {
const char *name = exportList[i];
NameToSymbolMap::iterator itr = allSymbols.find(name);
if (itr != allSymbols.end())
exportList[i] = allSymbols[name]->getName();
}
std::string ErrMsg;
sys::Path TempDir = sys::Path::GetTemporaryDirectory(&ErrMsg);
if (TempDir.isEmpty()) {
cerr << "lto: " << ErrMsg << "\n";
return LTO_WRITE_FAILURE;
}
sys::Path tmpAsmFilePath(TempDir);
if (!tmpAsmFilePath.appendComponent("lto")) {
cerr << "lto: " << ErrMsg << "\n";
TempDir.eraseFromDisk(true);
return LTO_WRITE_FAILURE;
}
if (tmpAsmFilePath.createTemporaryFileOnDisk(&ErrMsg)) {
cerr << "lto: " << ErrMsg << "\n";
TempDir.eraseFromDisk(true);
return LTO_WRITE_FAILURE;
}
sys::RemoveFileOnSignal(tmpAsmFilePath);
std::ofstream asmFile(tmpAsmFilePath.c_str(), io_mode);
if (!asmFile.is_open() || asmFile.bad()) {
if (tmpAsmFilePath.exists()) {
tmpAsmFilePath.eraseFromDisk();
TempDir.eraseFromDisk(true);
}
return LTO_WRITE_FAILURE;
}
enum LTOStatus status = optimize(bigOne, asmFile, exportList);
asmFile.close();
if (status != LTO_OPT_SUCCESS) {
tmpAsmFilePath.eraseFromDisk();
TempDir.eraseFromDisk(true);
return status;
}
if (saveTemps) {
std::string tempFileName(FinalOutputPath.c_str());
tempFileName += "1.bc";
std::ofstream Out(tempFileName.c_str(), io_mode);
OStream L(Out);
WriteBytecodeToFile(bigOne, L);
}
targetTriple = bigOne->getTargetTriple();
// Run GCC to assemble and link the program into native code.
//
// Note:
// We can't just assemble and link the file with the system assembler
// and linker because we don't know where to put the _start symbol.
// GCC mysteriously knows how to do it.
const sys::Path gcc = sys::Program::FindProgramByName("gcc");
if (gcc.isEmpty()) {
tmpAsmFilePath.eraseFromDisk();
TempDir.eraseFromDisk(true);
return LTO_ASM_FAILURE;
}
std::vector<const char*> args;
args.push_back(gcc.c_str());
args.push_back("-c");
args.push_back("-x");
args.push_back("assembler");
args.push_back("-o");
args.push_back(OutputFilename.c_str());
args.push_back(tmpAsmFilePath.c_str());
args.push_back(0);
if (sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 1, 0, &ErrMsg)) {
cerr << "lto: " << ErrMsg << "\n";
return LTO_ASM_FAILURE;
}
tmpAsmFilePath.eraseFromDisk();
TempDir.eraseFromDisk(true);
return LTO_OPT_SUCCESS;
}
void LTO::printVersion() {
cl::PrintVersionMessage();
}
/// Unused pure-virtual destructor. Must remain empty.
LinkTimeOptimizer::~LinkTimeOptimizer() {}
/// Destruct LTO. Delete all modules, symbols and target.
LTO::~LTO() {
for (std::vector<Module *>::iterator itr = modules.begin(), e = modules.end();
itr != e; ++itr)
delete *itr;
modules.clear();
for (NameToSymbolMap::iterator itr = allSymbols.begin(), e = allSymbols.end();
itr != e; ++itr)
delete itr->second;
allSymbols.clear();
delete Target;
}