llvm-6502/tools/llvm-ld/Optimize.cpp
Owen Anderson b63c7b695f Turn on FastDSE by default.
Note: FastDSE now equals or exceeds the results of old DSE on all of SPEC2000 and SPEC2006. Unless major problems
show up in the testers, it will likely completely replace old DSE in the near future.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@39986 91177308-0d34-0410-b5e6-96231b3b80d8
2007-07-17 21:59:21 +00:00

217 lines
8.0 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/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 {
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::alias ExportDynamic("export-dynamic",
cl::aliasopt(DisableInternalize),
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"),
cl::aliasopt(Strip));
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"),
cl::aliasopt(StripDebug));
// 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));
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.
if (!DisableInternalize)
addPass(Passes, createInternalizePass(true));
// 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, createFastDeadStoreEliminationPass()); // 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()());
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, createDeadCodeEliminationPass());
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);
}
}