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//===- 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/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 {
OPT_FAST_COMPILE = 1,
OPT_SIMPLE = 2,
OPT_AGGRESSIVE = 3,
OPT_LINK_TIME = 4,
OPT_AGGRESSIVE_LINK_TIME = 5
};
// Optimization Options
static cl::opt<OptimizationLevels> OptLevel(
cl::desc("Choose level of optimization to apply:"),
cl::init(OPT_FAST_COMPILE), cl::values(
clEnumValN(OPT_FAST_COMPILE,"O0",
"An alias for the -O1 option."),
clEnumValN(OPT_FAST_COMPILE,"O1",
"Optimize for linking speed, not execution speed."),
clEnumValN(OPT_SIMPLE,"O2",
"Perform only required/minimal optimizations"),
clEnumValN(OPT_AGGRESSIVE,"O3",
"An alias for the -O2 option."),
clEnumValN(OPT_LINK_TIME,"O4",
"Perform standard link time optimizations"),
clEnumValN(OPT_AGGRESSIVE_LINK_TIME,"O5",
"Perform aggressive link time optimizations"),
clEnumValEnd
)
);
static cl::opt<bool> DisableInline("disable-inlining",
cl::desc("Do not run the inliner pass"));
static cl::opt<bool>
DisableOptimizations("disable-opt",
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::opt<bool> Strip("s",
cl::desc("Strip symbol info from executable"));
static cl::alias ExportDynamic("export-dynamic",
cl::aliasopt(DisableInternalize),
cl::desc("Alias for -disable-internalize"));
// 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...
PM.add(P);
// If we are verifying all of the intermediate steps, add the verifier...
if (VerifyEach)
PM.add(createVerifierPass());
}
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)
Passes.add(createVerifierPass());
// Add an appropriate TargetData instance for this module...
addPass(Passes, new TargetData(M));
// 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.
addPass(Passes, createFunctionResolvingPass());
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));
// 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());
// 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.
if (Strip)
addPass(Passes, createStripSymbolsPass());
// Propagate constants at call sites into the functions they call.
addPass(Passes, createIPConstantPropagationPass());
// Remove unused arguments from functions...
addPass(Passes, createDeadArgEliminationPass());
if (!DisableInline)
addPass(Passes, createFunctionInliningPass()); // Inline small functions
addPass(Passes, createPruneEHPass()); // Remove dead EH info
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, 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());
}
// 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()());
else
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, createGlobalDCEPass());
}
// Make sure everything is still good.
Passes.add(createVerifierPass());
// Run our queue of passes all at once now, efficiently.
Passes.run(*M);
}
}
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