1 //===-- gccas.cpp - The "optimizing assembler" used by the GCC frontend ---===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This utility is designed to be used by the GCC frontend for creating bytecode
11 // files from its intermediate LLVM assembly. The requirements for this utility
12 // are thus slightly different than that of the standard `as' util.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Module.h"
17 #include "llvm/PassManager.h"
18 #include "llvm/Analysis/LoadValueNumbering.h"
19 #include "llvm/Analysis/Verifier.h"
20 #include "llvm/Assembly/Parser.h"
21 #include "llvm/Bytecode/WriteBytecodePass.h"
22 #include "llvm/Target/TargetData.h"
23 #include "llvm/Transforms/IPO.h"
24 #include "llvm/Transforms/Scalar.h"
25 #include "llvm/Support/CommandLine.h"
26 #include "llvm/System/Signals.h"
34 InputFilename(cl::Positional,cl::desc("<input llvm assembly>"),cl::init("-"));
37 OutputFilename("o", cl::desc("Override output filename"),
38 cl::value_desc("filename"));
41 Verify("verify", cl::desc("Verify each pass result"));
44 DisableInline("disable-inlining", cl::desc("Do not run the inliner pass"));
47 DisableOptimizations("disable-opt",
48 cl::desc("Do not run any optimization passes"));
51 DisableDSE("disable-dse", cl::desc("Do not run dead store elimination"));
55 static inline void addPass(PassManager &PM, Pass *P) {
56 // Add the pass to the pass manager...
59 // If we are verifying all of the intermediate steps, add the verifier...
60 if (Verify) PM.add(createVerifierPass());
64 void AddConfiguredTransformationPasses(PassManager &PM) {
65 PM.add(createVerifierPass()); // Verify that input is correct
66 addPass(PM, createLowerSetJmpPass()); // Lower llvm.setjmp/.longjmp
67 addPass(PM, createFunctionResolvingPass()); // Resolve (...) functions
69 if (DisableOptimizations) return;
71 addPass(PM, createRaiseAllocationsPass()); // call %malloc -> malloc inst
72 addPass(PM, createCFGSimplificationPass()); // Clean up disgusting code
73 addPass(PM, createPromoteMemoryToRegister()); // Kill useless allocas
74 addPass(PM, createGlobalOptimizerPass()); // Optimize out global vars
75 addPass(PM, createGlobalDCEPass()); // Remove unused fns and globs
76 addPass(PM, createIPConstantPropagationPass());// IP Constant Propagation
77 addPass(PM, createDeadArgEliminationPass()); // Dead argument elimination
78 addPass(PM, createInstructionCombiningPass()); // Clean up after IPCP & DAE
79 addPass(PM, createCFGSimplificationPass()); // Clean up after IPCP & DAE
81 addPass(PM, createPruneEHPass()); // Remove dead EH info
84 addPass(PM, createFunctionInliningPass()); // Inline small functions
85 addPass(PM, createArgumentPromotionPass()); // Scalarize uninlined fn args
87 addPass(PM, createRaisePointerReferencesPass());// Recover type information
88 addPass(PM, createTailDuplicationPass()); // Simplify cfg by copying code
89 addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
90 addPass(PM, createScalarReplAggregatesPass()); // Break up aggregate allocas
91 addPass(PM, createInstructionCombiningPass()); // Combine silly seq's
93 addPass(PM, createReassociatePass()); // Reassociate expressions
94 addPass(PM, createInstructionCombiningPass()); // Combine silly seq's
95 addPass(PM, createTailCallEliminationPass()); // Eliminate tail calls
96 addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
97 addPass(PM, createLICMPass()); // Hoist loop invariants
98 addPass(PM, createInstructionCombiningPass()); // Clean up after the unroller
99 addPass(PM, createIndVarSimplifyPass()); // Canonicalize indvars
100 addPass(PM, createLoopUnrollPass()); // Unroll small loops
101 addPass(PM, createInstructionCombiningPass()); // Clean up after the unroller
102 addPass(PM, createLoadValueNumberingPass()); // GVN for load instructions
103 addPass(PM, createGCSEPass()); // Remove common subexprs
104 addPass(PM, createSCCPPass()); // Constant prop with SCCP
106 // Run instcombine after redundancy elimination to exploit opportunities
107 // opened up by them.
108 addPass(PM, createInstructionCombiningPass());
110 addPass(PM, createDeadStoreEliminationPass()); // Delete dead stores
111 addPass(PM, createAggressiveDCEPass()); // SSA based 'Aggressive DCE'
112 addPass(PM, createCFGSimplificationPass()); // Merge & remove BBs
113 addPass(PM, createDeadTypeEliminationPass()); // Eliminate dead types
114 addPass(PM, createConstantMergePass()); // Merge dup global constants
118 int main(int argc, char **argv) {
119 cl::ParseCommandLineOptions(argc, argv, " llvm .s -> .o assembler for GCC\n");
120 sys::PrintStackTraceOnErrorSignal();
122 std::auto_ptr<Module> M;
124 // Parse the file now...
125 M.reset(ParseAssemblyFile(InputFilename));
126 } catch (const ParseException &E) {
127 std::cerr << argv[0] << ": " << E.getMessage() << "\n";
132 std::cerr << argv[0] << ": assembly didn't read correctly.\n";
136 std::ostream *Out = 0;
137 if (OutputFilename == "") { // Didn't specify an output filename?
138 if (InputFilename == "-") {
139 OutputFilename = "-";
141 std::string IFN = InputFilename;
142 int Len = IFN.length();
143 if (IFN[Len-2] == '.' && IFN[Len-1] == 's') { // Source ends in .s?
144 OutputFilename = std::string(IFN.begin(), IFN.end()-2);
146 OutputFilename = IFN; // Append a .o to it
148 OutputFilename += ".o";
152 if (OutputFilename == "-")
155 Out = new std::ofstream(OutputFilename.c_str(), std::ios::out);
157 // Make sure that the Out file gets unlinked from the disk if we get a
159 sys::RemoveFileOnSignal(OutputFilename);
164 std::cerr << argv[0] << ": error opening " << OutputFilename << "!\n";
168 // In addition to just parsing the input from GCC, we also want to spiff it up
169 // a little bit. Do this now.
173 // Add an appropriate TargetData instance for this module...
174 Passes.add(new TargetData("gccas", M.get()));
176 // Add all of the transformation passes to the pass manager to do the cleanup
177 // and optimization of the GCC output.
179 AddConfiguredTransformationPasses(Passes);
181 // Make sure everything is still good.
182 Passes.add(createVerifierPass());
184 // Write bytecode to file...
185 Passes.add(new WriteBytecodePass(Out));
187 // Run our queue of passes all at once now, efficiently.
188 Passes.run(*M.get());
190 if (Out != &std::cout) delete Out;