1 //===----------------------------------------------------------------------===//
2 // LLVM 'GCCAS' UTILITY
4 // This utility is designed to be used by the GCC frontend for creating
5 // bytecode files from it's intermediate llvm assembly. The requirements for
6 // this utility are thus slightly different than that of the standard as util.
8 //===----------------------------------------------------------------------===//
10 #include "llvm/Module.h"
11 #include "llvm/PassManager.h"
12 #include "llvm/Assembly/Parser.h"
13 #include "llvm/Transforms/CleanupGCCOutput.h"
14 #include "llvm/Transforms/LevelChange.h"
15 #include "llvm/Transforms/ConstantMerge.h"
16 #include "llvm/Transforms/ChangeAllocations.h"
17 #include "llvm/Transforms/Scalar.h"
18 #include "llvm/Analysis/Verifier.h"
19 #include "llvm/Bytecode/WriteBytecodePass.h"
20 #include "Support/CommandLine.h"
21 #include "Support/Signals.h"
26 static cl::String InputFilename ("", "Parse <arg> file, compile to bytecode",
28 static cl::String OutputFilename ("o", "Override output filename");
29 static cl::Int RunNPasses ("stopAfterNPasses", "Only run the first N "
30 "passes of gccas", cl::Hidden);
31 static cl::Flag StopAtLevelRaise("stopraise", "Stop optimization before "
32 "level raise", cl::Hidden);
33 static cl::Flag Verify ("verify", "Verify each pass result");
35 static inline void addPass(PassManager &PM, Pass *P) {
36 static int NumPassesCreated = 0;
38 // If we haven't already created the number of passes that was requested...
39 if (RunNPasses == 0 || RunNPasses > NumPassesCreated) {
40 // Add the pass to the pass manager...
43 // If we are verifying all of the intermediate steps, add the verifier...
44 if (Verify) PM.add(createVerifierPass());
46 // Keep track of how many passes we made for -stopAfterNPasses
52 void AddConfiguredTransformationPasses(PassManager &PM) {
53 if (Verify) PM.add(createVerifierPass());
55 addPass(PM, createFunctionResolvingPass()); // Resolve (...) functions
56 addPass(PM, createConstantMergePass()); // Merge dup global constants
57 addPass(PM, createDeadInstEliminationPass()); // Remove Dead code/vars
58 addPass(PM, createRaiseAllocationsPass()); // call %malloc -> malloc inst
59 addPass(PM, createCleanupGCCOutputPass()); // Fix gccisms
60 addPass(PM, createIndVarSimplifyPass()); // Simplify indvars
62 // Level raise is eternally buggy/in need of enhancements. Allow
63 // transformation to stop right before it runs.
64 if (StopAtLevelRaise) return;
66 addPass(PM, createRaisePointerReferencesPass());// Eliminate casts
67 addPass(PM, createPromoteMemoryToRegister()); // Promote alloca's to regs
68 addPass(PM, createReassociatePass()); // Reassociate expressions
69 addPass(PM, createInstructionCombiningPass()); // Combine silly seq's
70 addPass(PM, createDeadInstEliminationPass()); // Kill InstCombine remnants
71 addPass(PM, createLICMPass()); // Hoist loop invariants
72 addPass(PM, createGCSEPass()); // Remove common subexprs
73 addPass(PM, createSCCPPass()); // Constant prop with SCCP
75 // Run instcombine after redundancy elimination to exploit opportunities
77 addPass(PM, createInstructionCombiningPass());
78 addPass(PM, createAggressiveDCEPass()); // SSA based 'Agressive DCE'
79 addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
83 int main(int argc, char **argv) {
84 cl::ParseCommandLineOptions(argc, argv, " llvm .s -> .o assembler for GCC\n");
86 std::auto_ptr<Module> M;
88 // Parse the file now...
89 M.reset(ParseAssemblyFile(InputFilename));
90 } catch (const ParseException &E) {
91 cerr << E.getMessage() << "\n";
96 cerr << "assembly didn't read correctly.\n";
100 if (OutputFilename == "") { // Didn't specify an output filename?
101 std::string IFN = InputFilename;
102 int Len = IFN.length();
103 if (IFN[Len-2] == '.' && IFN[Len-1] == 's') { // Source ends in .s?
104 OutputFilename = std::string(IFN.begin(), IFN.end()-2);
106 OutputFilename = IFN; // Append a .o to it
108 OutputFilename += ".o";
111 std::ofstream Out(OutputFilename.c_str(), std::ios::out);
113 cerr << "Error opening " << OutputFilename << "!\n";
117 // Make sure that the Out file gets unlink'd from the disk if we get a SIGINT
118 RemoveFileOnSignal(OutputFilename);
120 // In addition to just parsing the input from GCC, we also want to spiff it up
121 // a little bit. Do this now.
125 // Add all of the transformation passes to the pass manager to do the cleanup
126 // and optimization of the GCC output.
128 AddConfiguredTransformationPasses(Passes);
130 // Write bytecode to file...
131 Passes.add(new WriteBytecodePass(&Out));
133 // Run our queue of passes all at once now, efficiently.
134 Passes.run(*M.get());