blob: 96a8860e18a5a753a4a5847b50d68174d35d85bb [file] [log] [blame]
//===- Optimize.cpp - Optimize a complete program -------------------------===//
// The LLVM Compiler Infrastructure
// This file was developed by Reid Spencer and is distributed under the
// University of Illinois Open Source License. See LICENSE.TXT for details.
// This file implements all optimization of the linked module for llvm-ld.
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Analysis/LoadValueNumbering.h"
#include "llvm/Analysis/Passes.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/System/DynamicLibrary.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Support/PassNameParser.h"
#include "llvm/Support/PluginLoader.h"
#include <iostream>
using namespace llvm;
// Pass Name Options as generated by the PassNameParser
static cl::list<const PassInfo*, bool, PassNameParser>
OptimizationList(cl::desc("Optimizations available:"));
// Optimization Enumeration
enum OptimizationLevels {
// Optimization Options
static cl::opt<OptimizationLevels> OptLevel(
cl::desc("Choose level of optimization to apply:"),
cl::init(OPT_FAST_COMPILE), cl::values(
"An alias for the -O1 option."),
"Optimize for linking speed, not execution speed."),
"Perform only required/minimal optimizations"),
"An alias for the -O2 option."),
"Perform standard link time optimizations"),
"Perform aggressive link time optimizations"),
static cl::opt<bool> DisableInline("disable-inlining",
cl::desc("Do not run the inliner pass"));
static cl::opt<bool>
cl::desc("Do not run any optimization passes"));
static cl::opt<bool> DisableInternalize("disable-internalize",
cl::desc("Do not mark all symbols as internal"));
static cl::opt<bool> VerifyEach("verify-each",
cl::desc("Verify intermediate results of all passes"));
static cl::alias ExportDynamic("export-dynamic",
cl::desc("Alias for -disable-internalize"));
static cl::opt<bool> Strip("strip-all",
cl::desc("Strip all symbol info from executable"));
static cl::alias A0("s", cl::desc("Alias for --strip-all"),
static cl::opt<bool> StripDebug("strip-debug",
cl::desc("Strip debugger symbol info from executable"));
static cl::alias A1("S", cl::desc("Alias for --strip-debug"),
// A utility function that adds a pass to the pass manager but will also add
// a verifier pass after if we're supposed to verify.
static inline void addPass(PassManager &PM, Pass *P) {
// Add the pass to the pass manager...
// If we are verifying all of the intermediate steps, add the verifier...
if (VerifyEach)
namespace llvm {
/// Optimize - Perform link time optimizations. This will run the scalar
/// optimizations, any loaded plugin-optimization modules, and then the
/// inter-procedural optimizations if applicable.
void Optimize(Module* M) {
// Instantiate the pass manager to organize the passes.
PassManager Passes;
// If we're verifying, start off with a verification pass.
if (VerifyEach)
// Add an appropriate TargetData instance for this module...
addPass(Passes, new TargetData(M));
if (!DisableOptimizations) {
// Now that composite has been compiled, scan through the module, looking
// for a main function. If main is defined, mark all other functions
// internal.
addPass(Passes, createInternalizePass(!DisableInternalize));
// 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.
addPass(Passes, createIPSCCPPass());
// Now that we internalized some globals, see if we can hack on them!
addPass(Passes, createGlobalOptimizerPass());
// Linking modules together can lead to duplicated global constants, only
// keep one copy of each constant...
addPass(Passes, createConstantMergePass());
// Remove unused arguments from functions...
addPass(Passes, 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.
addPass(Passes, createInstructionCombiningPass());
if (!DisableInline)
addPass(Passes, createFunctionInliningPass()); // Inline small functions
addPass(Passes, createPruneEHPass()); // Remove dead EH info
addPass(Passes, createGlobalOptimizerPass()); // Optimize globals again.
addPass(Passes, 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.
addPass(Passes, createArgumentPromotionPass());
// The IPO passes may leave cruft around. Clean up after them.
addPass(Passes, createInstructionCombiningPass());
addPass(Passes, createScalarReplAggregatesPass()); // Break up allocas
// Run a few AA driven optimizations here and now, to cleanup the code.
addPass(Passes, createGlobalsModRefPass()); // IP alias analysis
addPass(Passes, createLICMPass()); // Hoist loop invariants
addPass(Passes, createLoadValueNumberingPass()); // GVN for load instrs
addPass(Passes, createGCSEPass()); // Remove common subexprs
addPass(Passes, createDeadStoreEliminationPass()); // Nuke dead stores
// Cleanup and simplify the code after the scalar optimizations.
addPass(Passes, createInstructionCombiningPass());
// Delete basic blocks, which optimization passes may have killed...
addPass(Passes, createCFGSimplificationPass());
// Now that we have optimized the program, discard unreachable functions...
addPass(Passes, createGlobalDCEPass());
// If the -s or -S command line options were specified, strip the symbols out
// of the resulting program to make it smaller. -s and -S are GNU ld options
// that we are supporting; they alias -strip-all and -strip-debug.
if (Strip || StripDebug)
addPass(Passes, createStripSymbolsPass(StripDebug && !Strip));
// Create a new optimization pass for each one specified on the command line
std::auto_ptr<TargetMachine> target;
for (unsigned i = 0; i < OptimizationList.size(); ++i) {
const PassInfo *Opt = OptimizationList[i];
if (Opt->getNormalCtor())
addPass(Passes, Opt->getNormalCtor()());
std::cerr << "llvm-ld: cannot create pass: " << Opt->getPassName()
<< "\n";
// The user's passes may leave cruft around. Clean up after them them but
// only if we haven't got DisableOptimizations set
if (!DisableOptimizations) {
addPass(Passes, createInstructionCombiningPass());
addPass(Passes, createCFGSimplificationPass());
addPass(Passes, createDeadCodeEliminationPass());
addPass(Passes, createGlobalDCEPass());
// Make sure everything is still good.
// Run our queue of passes all at once now, efficiently.*M);