llvm/tools/llvm-ld/Optimize.cpp
2004-12-11 03:03:54 +00:00

195 lines
6.9 KiB
C++

//===- 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/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
using namespace llvm;
// Optimization Options
enum OptimizationLevels {
OPT_FAST_COMPILE = 1,
OPT_SIMPLE = 2,
OPT_AGGRESSIVE = 3,
OPT_LINK_TIME = 4,
OPT_AGGRESSIVE_LINK_TIME = 5
};
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> Verify("verify",
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"));
static cl::list<std::string> LoadableModules("load",
cl::value_desc("path to loadable optimization module"),
cl::desc("Load an optimization module and run it"));
// 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 (Verify)
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 (Verify)
Passes.add(createVerifierPass());
// Add an appropriate TargetData instance for this module...
addPass(Passes, new TargetData("gccld", 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) {
if (!DisableInternalize) {
// 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());
}
// 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 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());
}
std::vector<std::string> plugins = LoadableModules;
for (std::vector<std::string>::iterator I = plugins.begin(),
E = plugins.end(); I != E; ++I) {
sys::DynamicLibrary dll(I->c_str());
typedef void (*OptimizeFunc)(PassManager&,int);
OptimizeFunc OF = OptimizeFunc(
dll.GetAddressOfSymbol("RunOptimizations"));
if (OF == 0) {
throw std::string("Optimization Module '") + *I +
"' is missing the RunOptimizations symbol";
}
(*OF)(Passes,OptLevel);
}
// Make sure everything is still good.
Passes.add(createVerifierPass());
// Run our queue of passes all at once now, efficiently.
Passes.run(*M);
}
}