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//===----------------------------------------------------------------------===//
// LLVM 'GCCAS' UTILITY
//
// This utility is designed to be used by the GCC frontend for creating
// bytecode files from it's intermediate llvm assembly. The requirements for
// this utility are thus slightly different than that of the standard as util.
//
//===----------------------------------------------------------------------===//
#include "llvm/Module.h"
#include "llvm/PassManager.h"
#include "llvm/Assembly/Parser.h"
#include "llvm/Transforms/CleanupGCCOutput.h"
#include "llvm/Transforms/LevelChange.h"
#include "llvm/Transforms/ConstantMerge.h"
#include "llvm/Transforms/ChangeAllocations.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Bytecode/WriteBytecodePass.h"
#include "Support/CommandLine.h"
#include "Support/Signals.h"
#include <memory>
#include <fstream>
using std::cerr;
static cl::String InputFilename ("", "Parse <arg> file, compile to bytecode",
cl::Required, "");
static cl::String OutputFilename ("o", "Override output filename");
static cl::Int RunNPasses ("stopAfterNPasses", "Only run the first N "
"passes of gccas", cl::Hidden);
static cl::Flag StopAtLevelRaise("stopraise", "Stop optimization before "
"level raise", cl::Hidden);
static cl::Flag Verify ("verify", "Verify each pass result");
static inline void addPass(PassManager &PM, Pass *P) {
static int NumPassesCreated = 0;
// If we haven't already created the number of passes that was requested...
if (RunNPasses == 0 || RunNPasses > NumPassesCreated) {
// 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());
// Keep track of how many passes we made for -stopAfterNPasses
++NumPassesCreated;
}
}
void AddConfiguredTransformationPasses(PassManager &PM) {
if (Verify) PM.add(createVerifierPass());
addPass(PM, createFunctionResolvingPass()); // Resolve (...) functions
addPass(PM, createConstantMergePass()); // Merge dup global constants
addPass(PM, createDeadInstEliminationPass()); // Remove Dead code/vars
addPass(PM, createRaiseAllocationsPass()); // call %malloc -> malloc inst
addPass(PM, createCleanupGCCOutputPass()); // Fix gccisms
addPass(PM, createIndVarSimplifyPass()); // Simplify indvars
// Level raise is eternally buggy/in need of enhancements. Allow
// transformation to stop right before it runs.
if (StopAtLevelRaise) return;
addPass(PM, createRaisePointerReferencesPass());// Eliminate casts
addPass(PM, createPromoteMemoryToRegister()); // Promote alloca's to regs
/* addPass(PM, createReassociatePass());*/ // Reassociate expressions
addPass(PM, createInstructionCombiningPass()); // Combine silly seq's
addPass(PM, createDeadInstEliminationPass()); // Kill InstCombine remnants
addPass(PM, createLICMPass()); // Hoist loop invariants
addPass(PM, createGCSEPass()); // Remove common subexprs
addPass(PM, createSCCPPass()); // Constant prop with SCCP
// Run instcombine after redundancy elimination to exploit opportunities
// opened up by them.
addPass(PM, createInstructionCombiningPass());
addPass(PM, createAggressiveDCEPass()); // SSA based 'Agressive DCE'
addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
}
int main(int argc, char **argv) {
cl::ParseCommandLineOptions(argc, argv, " llvm .s -> .o assembler for GCC\n");
std::auto_ptr<Module> M;
try {
// Parse the file now...
M.reset(ParseAssemblyFile(InputFilename));
} catch (const ParseException &E) {
cerr << E.getMessage() << std::endl;
return 1;
}
if (M.get() == 0) {
cerr << "assembly didn't read correctly.\n";
return 1;
}
if (OutputFilename == "") { // Didn't specify an output filename?
std::string IFN = InputFilename;
int Len = IFN.length();
if (IFN[Len-2] == '.' && IFN[Len-1] == 's') { // Source ends in .s?
OutputFilename = std::string(IFN.begin(), IFN.end()-2);
} else {
OutputFilename = IFN; // Append a .o to it
}
OutputFilename += ".o";
}
std::ofstream Out(OutputFilename.c_str(), std::ios::out);
if (!Out.good()) {
cerr << "Error opening " << OutputFilename << "!\n";
return 1;
}
// Make sure that the Out file gets unlink'd from the disk if we get a SIGINT
RemoveFileOnSignal(OutputFilename);
// In addition to just parsing the input from GCC, we also want to spiff it up
// a little bit. Do this now.
//
PassManager Passes;
// Add all of the transformation passes to the pass manager to do the cleanup
// and optimization of the GCC output.
//
AddConfiguredTransformationPasses(Passes);
// Write bytecode to file...
Passes.add(new WriteBytecodePass(&Out));
// Run our queue of passes all at once now, efficiently.
Passes.run(*M.get());
return 0;
}
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