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//===-- gccas.cpp - The "optimizing assembler" used by the GCC frontend ---===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This utility is designed to be used by the GCC frontend for creating bytecode
// files from its 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/Analysis/LoadValueNumbering.h"
#include "llvm/Analysis/Verifier.h"
#include "llvm/Assembly/Parser.h"
#include "llvm/Bytecode/WriteBytecodePass.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Transforms/IPO.h"
#include "llvm/Transforms/Scalar.h"
#include "Support/CommandLine.h"
#include "llvm/System/Signals.h"
#include <memory>
#include <fstream>
using namespace llvm;
namespace {
cl::opt<std::string>
InputFilename(cl::Positional,cl::desc("<input llvm assembly>"),cl::init("-"));
cl::opt<std::string>
OutputFilename("o", cl::desc("Override output filename"),
cl::value_desc("filename"));
cl::opt<bool>
Verify("verify", cl::desc("Verify each pass result"));
cl::opt<bool>
DisableInline("disable-inlining", cl::desc("Do not run the inliner pass"));
cl::opt<bool>
DisableOptimizations("disable-opt",
cl::desc("Do not run any optimization passes"));
cl::opt<bool>
DisableDSE("disable-dse", cl::desc("Do not run dead store elimination"));
}
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());
}
void AddConfiguredTransformationPasses(PassManager &PM) {
PM.add(createVerifierPass()); // Verify that input is correct
addPass(PM, createLowerSetJmpPass()); // Lower llvm.setjmp/.longjmp
addPass(PM, createFunctionResolvingPass()); // Resolve (...) functions
if (DisableOptimizations) return;
addPass(PM, createRaiseAllocationsPass()); // call %malloc -> malloc inst
addPass(PM, createCFGSimplificationPass()); // Clean up disgusting code
addPass(PM, createPromoteMemoryToRegister()); // Kill useless allocas
addPass(PM, createGlobalConstifierPass()); // Mark read-only globals const
addPass(PM, createGlobalDCEPass()); // Remove unused globals
addPass(PM, createIPConstantPropagationPass());// IP Constant Propagation
addPass(PM, createDeadArgEliminationPass()); // Dead argument elimination
addPass(PM, createInstructionCombiningPass()); // Clean up after IPCP & DAE
addPass(PM, createCFGSimplificationPass()); // Clean up after IPCP & DAE
addPass(PM, createPruneEHPass()); // Remove dead EH info
if (!DisableInline)
addPass(PM, createFunctionInliningPass()); // Inline small functions
addPass(PM, createArgumentPromotionPass()); // Scalarize uninlined fn args
addPass(PM, createRaisePointerReferencesPass());// Recover type information
addPass(PM, createTailDuplicationPass()); // Simplify cfg by copying code
addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
addPass(PM, createScalarReplAggregatesPass()); // Break up aggregate allocas
addPass(PM, createInstructionCombiningPass()); // Combine silly seq's
addPass(PM, createReassociatePass()); // Reassociate expressions
addPass(PM, createInstructionCombiningPass()); // Combine silly seq's
addPass(PM, createTailCallEliminationPass()); // Eliminate tail calls
addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
addPass(PM, createLICMPass()); // Hoist loop invariants
addPass(PM, createInstructionCombiningPass()); // Clean up after the unroller
addPass(PM, createIndVarSimplifyPass()); // Canonicalize indvars
addPass(PM, createLoopUnrollPass()); // Unroll small loops
addPass(PM, createInstructionCombiningPass()); // Clean up after the unroller
addPass(PM, createLoadValueNumberingPass()); // GVN for load instructions
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());
if (!DisableDSE)
addPass(PM, createDeadStoreEliminationPass()); // Delete dead stores
addPass(PM, createAggressiveDCEPass()); // SSA based 'Aggressive DCE'
addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
addPass(PM, createDeadTypeEliminationPass()); // Eliminate dead types
addPass(PM, createConstantMergePass()); // Merge dup global constants
}
int main(int argc, char **argv) {
cl::ParseCommandLineOptions(argc, argv, " llvm .s -> .o assembler for GCC\n");
sys::PrintStackTraceOnErrorSignal();
std::auto_ptr<Module> M;
try {
// Parse the file now...
M.reset(ParseAssemblyFile(InputFilename));
} catch (const ParseException &E) {
std::cerr << argv[0] << ": " << E.getMessage() << "\n";
return 1;
}
if (M.get() == 0) {
std::cerr << argv[0] << ": assembly didn't read correctly.\n";
return 1;
}
std::ostream *Out = 0;
if (OutputFilename == "") { // Didn't specify an output filename?
if (InputFilename == "-") {
OutputFilename = "-";
} else {
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";
}
}
if (OutputFilename == "-")
Out = &std::cout;
else {
Out = new std::ofstream(OutputFilename.c_str(), std::ios::out);
// Make sure that the Out file gets unlinked from the disk if we get a
// signal
sys::RemoveFileOnSignal(OutputFilename);
}
if (!Out->good()) {
std::cerr << argv[0] << ": error opening " << OutputFilename << "!\n";
return 1;
}
// 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 an appropriate TargetData instance for this module...
Passes.add(new TargetData("gccas", M.get()));
// Add all of the transformation passes to the pass manager to do the cleanup
// and optimization of the GCC output.
//
AddConfiguredTransformationPasses(Passes);
// Make sure everything is still good.
Passes.add(createVerifierPass());
// Write bytecode to file...
Passes.add(new WriteBytecodePass(Out));
// Run our queue of passes all at once now, efficiently.
Passes.run(*M.get());
if (Out != &std::cout) delete Out;
return 0;
}
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