llvm-6502/tools/lto/LTOCodeGenerator.cpp

472 lines
16 KiB
C++
Raw Normal View History

//===-LTOCodeGenerator.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 the Link Time Optimization library. This library is
// intended to be used by linker to optimize code at link time.
//
//===----------------------------------------------------------------------===//
#include "LTOModule.h"
#include "LTOCodeGenerator.h"
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Linker.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/ModuleProvider.h"
#include "llvm/Bitcode/ReaderWriter.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/Mangler.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/raw_ostream.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/TargetOptions.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/ADT/StringExtras.h"
#include "llvm/Config/config.h"
#include <fstream>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
using namespace llvm;
static cl::opt<bool> DisableInline("disable-inlining",
cl::desc("Do not run the inliner pass"));
const char* LTOCodeGenerator::getVersionString()
{
#ifdef LLVM_VERSION_INFO
return PACKAGE_NAME " version " PACKAGE_VERSION ", " LLVM_VERSION_INFO;
#else
return PACKAGE_NAME " version " PACKAGE_VERSION;
#endif
}
LTOCodeGenerator::LTOCodeGenerator()
: _linker("LinkTimeOptimizer", "ld-temp.o"), _target(NULL),
_emitDwarfDebugInfo(false), _scopeRestrictionsDone(false),
_codeModel(LTO_CODEGEN_PIC_MODEL_DYNAMIC),
_nativeObjectFile(NULL)
{
}
LTOCodeGenerator::~LTOCodeGenerator()
{
delete _target;
delete _nativeObjectFile;
}
bool LTOCodeGenerator::addModule(LTOModule* mod, std::string& errMsg)
{
return _linker.LinkInModule(mod->getLLVVMModule(), &errMsg);
}
bool LTOCodeGenerator::setDebugInfo(lto_debug_model debug, std::string& errMsg)
{
switch (debug) {
case LTO_DEBUG_MODEL_NONE:
_emitDwarfDebugInfo = false;
return false;
case LTO_DEBUG_MODEL_DWARF:
_emitDwarfDebugInfo = true;
return false;
}
errMsg = "unknown debug format";
return true;
}
bool LTOCodeGenerator::setCodePICModel(lto_codegen_model model,
std::string& errMsg)
{
switch (model) {
case LTO_CODEGEN_PIC_MODEL_STATIC:
case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
_codeModel = model;
return false;
}
errMsg = "unknown pic model";
return true;
}
void LTOCodeGenerator::addMustPreserveSymbol(const char* sym)
{
_mustPreserveSymbols[sym] = 1;
}
bool LTOCodeGenerator::writeMergedModules(const char* path, std::string& errMsg)
{
if ( this->determineTarget(errMsg) )
return true;
// mark which symbols can not be internalized
this->applyScopeRestrictions();
// create output file
std::ofstream out(path, std::ios_base::out|std::ios::trunc|std::ios::binary);
if ( out.fail() ) {
errMsg = "could not open bitcode file for writing: ";
errMsg += path;
return true;
}
// write bitcode to it
WriteBitcodeToFile(_linker.getModule(), out);
if ( out.fail() ) {
errMsg = "could not write bitcode file: ";
errMsg += path;
return true;
}
return false;
}
const void* LTOCodeGenerator::compile(size_t* length, std::string& errMsg)
{
// make unique temp .s file to put generated assembly code
sys::Path uniqueAsmPath("lto-llvm.s");
if ( uniqueAsmPath.createTemporaryFileOnDisk(true, &errMsg) )
return NULL;
sys::RemoveFileOnSignal(uniqueAsmPath);
// generate assembly code
bool genResult = false;
{
raw_fd_ostream asmFile(uniqueAsmPath.c_str(), false, errMsg);
if (!errMsg.empty())
return NULL;
genResult = this->generateAssemblyCode(asmFile, errMsg);
}
if ( genResult ) {
if ( uniqueAsmPath.exists() )
uniqueAsmPath.eraseFromDisk();
return NULL;
}
// make unique temp .o file to put generated object file
sys::PathWithStatus uniqueObjPath("lto-llvm.o");
if ( uniqueObjPath.createTemporaryFileOnDisk(true, &errMsg) ) {
if ( uniqueAsmPath.exists() )
uniqueAsmPath.eraseFromDisk();
return NULL;
}
sys::RemoveFileOnSignal(uniqueObjPath);
// assemble the assembly code
const std::string& uniqueObjStr = uniqueObjPath.toString();
bool asmResult = this->assemble(uniqueAsmPath.toString(),
uniqueObjStr, errMsg);
if ( !asmResult ) {
// remove old buffer if compile() called twice
delete _nativeObjectFile;
// read .o file into memory buffer
_nativeObjectFile = MemoryBuffer::getFile(uniqueObjStr.c_str(),&errMsg);
}
// remove temp files
uniqueAsmPath.eraseFromDisk();
uniqueObjPath.eraseFromDisk();
// return buffer, unless error
if ( _nativeObjectFile == NULL )
return NULL;
*length = _nativeObjectFile->getBufferSize();
return _nativeObjectFile->getBufferStart();
}
bool LTOCodeGenerator::assemble(const std::string& asmPath,
const std::string& objPath, std::string& errMsg)
{
// find compiler driver
const sys::Path gcc = sys::Program::FindProgramByName("gcc");
if ( gcc.isEmpty() ) {
errMsg = "can't locate gcc";
return true;
}
// build argument list
std::vector<const char*> args;
std::string targetTriple = _linker.getModule()->getTargetTriple();
args.push_back(gcc.c_str());
if ( targetTriple.find("darwin") != targetTriple.size() ) {
if (strncmp(targetTriple.c_str(), "i386-apple-", 11) == 0) {
args.push_back("-arch");
args.push_back("i386");
}
else if (strncmp(targetTriple.c_str(), "x86_64-apple-", 13) == 0) {
args.push_back("-arch");
args.push_back("x86_64");
}
else if (strncmp(targetTriple.c_str(), "powerpc-apple-", 14) == 0) {
args.push_back("-arch");
args.push_back("ppc");
}
else if (strncmp(targetTriple.c_str(), "powerpc64-apple-", 16) == 0) {
args.push_back("-arch");
args.push_back("ppc64");
}
}
args.push_back("-c");
args.push_back("-x");
args.push_back("assembler");
args.push_back("-o");
args.push_back(objPath.c_str());
args.push_back(asmPath.c_str());
args.push_back(0);
// invoke assembler
if ( sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 0, 0, &errMsg) ) {
errMsg = "error in assembly";
return true;
}
return false; // success
}
bool LTOCodeGenerator::determineTarget(std::string& errMsg)
{
if ( _target == NULL ) {
// create target machine from info for merged modules
Module* mergedModule = _linker.getModule();
const TargetMachineRegistry::entry* march =
TargetMachineRegistry::getClosestStaticTargetForModule(
*mergedModule, errMsg);
if ( march == NULL )
return true;
// construct LTModule, hand over ownership of module and target
std::string FeatureStr =
getFeatureString(_linker.getModule()->getTargetTriple().c_str());
_target = march->CtorFn(*mergedModule, FeatureStr.c_str());
}
return false;
}
void LTOCodeGenerator::applyScopeRestrictions()
{
if ( !_scopeRestrictionsDone ) {
Module* mergedModule = _linker.getModule();
// Start off with a verification pass.
PassManager passes;
passes.add(createVerifierPass());
// mark which symbols can not be internalized
if ( !_mustPreserveSymbols.empty() ) {
Mangler mangler(*mergedModule,
_target->getTargetAsmInfo()->getGlobalPrefix());
std::vector<const char*> mustPreserveList;
for (Module::iterator f = mergedModule->begin(),
e = mergedModule->end(); f != e; ++f) {
if ( !f->isDeclaration()
&& _mustPreserveSymbols.count(mangler.getValueName(f)) )
mustPreserveList.push_back(::strdup(f->getName().c_str()));
}
for (Module::global_iterator v = mergedModule->global_begin(),
e = mergedModule->global_end(); v != e; ++v) {
if ( !v->isDeclaration()
&& _mustPreserveSymbols.count(mangler.getValueName(v)) )
mustPreserveList.push_back(::strdup(v->getName().c_str()));
}
passes.add(createInternalizePass(mustPreserveList));
}
// apply scope restrictions
passes.run(*mergedModule);
_scopeRestrictionsDone = true;
}
}
/// Optimize merged modules using various IPO passes
bool LTOCodeGenerator::generateAssemblyCode(raw_ostream& out,
std::string& errMsg)
{
if ( this->determineTarget(errMsg) )
return true;
// mark which symbols can not be internalized
this->applyScopeRestrictions();
Module* mergedModule = _linker.getModule();
// If target supports exception handling then enable it now.
if ( _target->getTargetAsmInfo()->doesSupportExceptionHandling() )
llvm::ExceptionHandling = true;
// set codegen model
switch( _codeModel ) {
case LTO_CODEGEN_PIC_MODEL_STATIC:
_target->setRelocationModel(Reloc::Static);
break;
case LTO_CODEGEN_PIC_MODEL_DYNAMIC:
_target->setRelocationModel(Reloc::PIC_);
break;
case LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC:
_target->setRelocationModel(Reloc::DynamicNoPIC);
break;
}
// if options were requested, set them
if ( !_codegenOptions.empty() )
cl::ParseCommandLineOptions(_codegenOptions.size(),
(char**)&_codegenOptions[0]);
// Instantiate the pass manager to organize the passes.
PassManager passes;
// Start off with a verification pass.
passes.add(createVerifierPass());
// Add an appropriate TargetData instance for this module...
passes.add(new TargetData(*_target->getTargetData()));
// Propagate constants at call sites into the functions they call. This
// opens opportunities for globalopt (and inlining) by substituting function
// pointers passed as arguments to direct uses of functions.
passes.add(createIPSCCPPass());
// 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());
// Remove unused arguments from functions...
passes.add(createDeadArgEliminationPass());
// Reduce the code after globalopt and ipsccp. Both can open up significant
// simplification opportunities, and both can propagate functions through
// function pointers. When this happens, we often have to resolve varargs
// calls, etc, so let instcombine do this.
passes.add(createInstructionCombiningPass());
if (!DisableInline)
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(createJumpThreadingPass()); // Thread jumps.
passes.add(createScalarReplAggregatesPass()); // Break up allocas
// Run a few AA driven optimizations here and now, to cleanup the code.
passes.add(createFunctionAttrsPass()); // Add nocapture
passes.add(createGlobalsModRefPass()); // IP alias analysis
passes.add(createLICMPass()); // Hoist loop invariants
passes.add(createGVNPass()); // Remove common subexprs
passes.add(createMemCpyOptPass()); // Remove dead memcpy's
passes.add(createDeadStoreEliminationPass()); // Nuke dead stores
// Cleanup and simplify the code after the scalar optimizations.
passes.add(createInstructionCombiningPass());
passes.add(createJumpThreadingPass()); // Thread jumps.
passes.add(createPromoteMemoryToRegisterPass()); // Cleanup after threading.
// 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(mergedModule));
codeGenPasses->add(new TargetData(*_target->getTargetData()));
MachineCodeEmitter* mce = NULL;
switch (_target->addPassesToEmitFile(*codeGenPasses, out,
TargetMachine::AssemblyFile, false)) {
case FileModel::MachOFile:
mce = AddMachOWriter(*codeGenPasses, out, *_target);
break;
case FileModel::ElfFile:
mce = AddELFWriter(*codeGenPasses, out, *_target);
break;
case FileModel::AsmFile:
break;
case FileModel::Error:
case FileModel::None:
errMsg = "target file type not supported";
return true;
}
if (_target->addPassesToEmitFileFinish(*codeGenPasses, mce, false)) {
errMsg = "target does not support generation of this file type";
return true;
}
// Run our queue of passes all at once now, efficiently.
passes.run(*mergedModule);
// Run the code generator, and write assembly file
codeGenPasses->doInitialization();
for (Module::iterator
it = mergedModule->begin(), e = mergedModule->end(); it != e; ++it)
if (!it->isDeclaration())
codeGenPasses->run(*it);
codeGenPasses->doFinalization();
return false; // success
}
/// Optimize merged modules using various IPO passes
void LTOCodeGenerator::setCodeGenDebugOptions(const char* options)
{
std::string ops(options);
for (std::string o = getToken(ops); !o.empty(); o = getToken(ops)) {
// ParseCommandLineOptions() expects argv[0] to be program name.
// Lazily add that.
if ( _codegenOptions.empty() )
_codegenOptions.push_back("libLTO");
_codegenOptions.push_back(strdup(o.c_str()));
}
}