llvm-6502/tools/lto/lto.cpp
Devang Patel 2198f9cec4 untabify
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29686 91177308-0d34-0410-b5e6-96231b3b80d8
2006-08-14 23:37:18 +00:00

343 lines
12 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 implementes 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/SymbolTable.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/Verifier.h"
#include "llvm/Target/SubtargetFeature.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetMachineRegistry.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Analysis/LoadValueNumbering.h"
#include "llvm/LinkTimeOptimizer.h"
#include <fstream>
#include <iostream>
using namespace llvm;
extern "C"
llvm::LinkTimeOptimizer *createLLVMOptimizer()
{
llvm::LinkTimeOptimizer *l = new llvm::LinkTimeOptimizer();
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);
}
// Helper routine
// FIXME : Take advantage of GlobalPrefix from AsmPrinter
static const char *addUnderscore(const char *name) {
size_t namelen = strlen(name);
char *symName = (char*)malloc(namelen+2);
symName[0] = '_';
strcpy(&symName[1], name);
return symName;
}
// 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));
}
else 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);
}
/// 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
LinkTimeOptimizer::readLLVMObjectFile(const std::string &InputFilename,
NameToSymbolMap &symbols,
std::set<std::string> &references)
{
Module *m = ParseBytecodeFile(InputFilename);
if (!m)
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, "_");
modules.push_back(m);
for (Module::iterator f = m->begin(), e = m->end(); f != e; ++f) {
LTOLinkageTypes lt = getLTOLinkageType(f);
if (!f->isExternal() && lt != LTOInternalLinkage
&& strncmp (f->getName().c_str(), "llvm.", 5)) {
LLVMSymbol *newSymbol = new LLVMSymbol(lt, f, f->getName(),
mangler.getValueName(f));
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->isExternal() && lt != LTOInternalLinkage
&& strncmp (v->getName().c_str(), "llvm.", 5)) {
LLVMSymbol *newSymbol = new LLVMSymbol(lt, v, v->getName(),
mangler.getValueName(v));
symbols[newSymbol->getMangledName()] = newSymbol;
for (unsigned count = 0, total = v->getNumOperands();
count != total; ++count)
findExternalRefs(v->getOperand(count), references, mangler);
}
}
return LTO_READ_SUCCESS;
}
/// 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.
static 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
std::string Err;
const TargetMachineRegistry::Entry* March =
TargetMachineRegistry::getClosestStaticTargetForModule(*M, Err);
if (March == 0)
return LTO_NO_TARGET;
// Create target
std::string Features;
std::auto_ptr<TargetMachine> target(March->CtorFn(*M, Features));
if (!target.get())
return LTO_NO_TARGET;
TargetMachine &Target = *target.get();
// Start off with a verification pass.
Passes.add(createVerifierPass());
// Add an appropriate TargetData instance for this module...
Passes.add(new TargetData(*Target.getTargetData()));
// Often if the programmer does not specify proper prototypes for the
// functions they are calling, they end up calling a vararg version of the
// function that does not get a body filled in (the real function has typed
// arguments). This pass merges the two functions.
Passes.add(createFunctionResolvingPass());
// 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());
Target.addPassesToEmitFile(Passes, Out, TargetMachine::AssemblyFile, true);
// Run our queue of passes all at once now, efficiently.
Passes.run(*M);
return LTO_OPT_SUCCESS;
}
///Link all modules together and optimize them using IPO. Generate
/// native object file using OutputFilename
/// Return appropriate LTOStatus.
enum LTOStatus
LinkTimeOptimizer::optimizeModules(const std::string &OutputFilename,
std::vector<const char *> &exportList)
{
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;
#if 0
// Enable this when -save-temps is used
std::ofstream Out("big.bc", io_mode);
WriteBytecodeToFile(bigOne, Out, true);
#endif
// 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];
if (strlen(name) > 2 && name[0] == '_')
exportList[i] = &name[1];
}
sys::Path tmpAsmFilePath("/tmp/");
tmpAsmFilePath.createTemporaryFileOnDisk();
sys::RemoveFileOnSignal(tmpAsmFilePath);
std::ofstream asmFile(tmpAsmFilePath.c_str(), io_mode);
if (!asmFile.is_open() || asmFile.bad()) {
if (tmpAsmFilePath.exists())
tmpAsmFilePath.eraseFromDisk();
return LTO_WRITE_FAILURE;
}
enum LTOStatus status = lto_optimize(bigOne, asmFile, exportList);
asmFile.close();
if (status != LTO_OPT_SUCCESS) {
tmpAsmFilePath.eraseFromDisk();
return status;
}
// 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 = FindExecutable("gcc", "/");
if (gcc.isEmpty()) {
tmpAsmFilePath.eraseFromDisk();
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);
int R1 = sys::Program::ExecuteAndWait(gcc, &args[0], 0, 0, 1);
tmpAsmFilePath.eraseFromDisk();
return LTO_OPT_SUCCESS;
}