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      1 /*
      2  * Copyright 2013, The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *     http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 #include "llvm/Analysis/Verifier.h"
     18 #include "llvm/Bitcode/ReaderWriter.h"
     19 #include "llvm/IR/LLVMContext.h"
     20 #include "llvm/IR/Module.h"
     21 #include "llvm/IRReader/IRReader.h"
     22 #include "llvm/Pass.h"
     23 #include "llvm/PassManager.h"
     24 #include "llvm/Support/CommandLine.h"
     25 #include "llvm/Support/ManagedStatic.h"
     26 #include "llvm/Support/PrettyStackTrace.h"
     27 #include "llvm/Support/Signals.h"
     28 #include "llvm/Support/SourceMgr.h"
     29 #include "llvm/Support/SystemUtils.h"
     30 #include "llvm/Support/ToolOutputFile.h"
     31 using namespace llvm;
     32 
     33 static cl::list<std::string>
     34 InputFilenames(cl::Positional,
     35                cl::desc("<input bitcode files>"));
     36 
     37 static cl::opt<std::string>
     38 OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),
     39                cl::value_desc("filename"));
     40 
     41 static cl::opt<bool>
     42 OutputAssembly("S",
     43                cl::desc("Write output as LLVM assembly"), cl::Hidden);
     44 
     45 namespace {
     46   class StripAttributes : public ModulePass {
     47   public:
     48     static char ID;
     49 
     50     StripAttributes() : ModulePass(ID) {
     51     }
     52 
     53     bool runOnFunction(Function &F) {
     54       // Remove any target-cpu and/or target-features attributes from each
     55       // Function or Function declaration.
     56       if (F.hasFnAttribute("target-cpu") ||
     57           F.hasFnAttribute("target-features")) {
     58 
     59         AttrBuilder B;
     60         B.addAttribute("target-cpu").addAttribute("target-features");
     61         AttributeSet ToStrip = AttributeSet::get(F.getContext(),
     62             AttributeSet::FunctionIndex, B);
     63         F.removeAttributes(AttributeSet::FunctionIndex, ToStrip);
     64         return true;
     65       }
     66       return false;
     67     }
     68 
     69     // We have to use a ModulePass, since a FunctionPass only gets run on
     70     // defined Functions (and not declared Functions).
     71     virtual bool runOnModule(Module &M) {
     72       bool Changed = false;
     73       for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
     74         Changed |= runOnFunction(*I);
     75       }
     76       return Changed;
     77     }
     78   };
     79 
     80   llvm::ModulePass * createStripAttributePass() {
     81     return new StripAttributes();
     82   }
     83 }
     84 
     85 
     86 char StripAttributes::ID = 0;
     87 static RegisterPass<StripAttributes> RPSA("StripAttributes",
     88     "Strip Function Attributes Pass");
     89 
     90 
     91 static inline std::auto_ptr<Module> LoadFile(const char *argv0,
     92                                              const std::string &FN,
     93                                              LLVMContext& Context) {
     94   SMDiagnostic Err;
     95   Module* Result = ParseIRFile(FN, Err, Context);
     96   if (Result) {
     97     return std::auto_ptr<Module>(Result);   // Load successful!
     98   }
     99 
    100   Err.print(argv0, errs());
    101   return std::auto_ptr<Module>();
    102 }
    103 
    104 
    105 int main(int argc, char **argv) {
    106   // Print a stack trace if we signal out.
    107   sys::PrintStackTraceOnErrorSignal();
    108   PrettyStackTraceProgram X(argc, argv);
    109 
    110   LLVMContext &Context = getGlobalContext();
    111   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    112   cl::ParseCommandLineOptions(argc, argv, "strip function attribute pass\n");
    113 
    114   std::string ErrorMessage;
    115 
    116   std::auto_ptr<Module> M(LoadFile(argv[0], InputFilenames[0], Context));
    117   if (M.get() == 0) {
    118     errs() << argv[0] << ": error loading file '"
    119            << InputFilenames[0] << "'\n";
    120     return 1;
    121   }
    122 
    123   // Perform the actual function attribute stripping.
    124   PassManager PM;
    125   PM.add(createStripAttributePass());
    126   PM.run(*M.get());
    127 
    128   std::string ErrorInfo;
    129   tool_output_file Out(OutputFilename.c_str(), ErrorInfo,
    130                        sys::fs::F_Binary);
    131   if (!ErrorInfo.empty()) {
    132     errs() << ErrorInfo << '\n';
    133     return 1;
    134   }
    135 
    136   if (verifyModule(*M)) {
    137     errs() << argv[0] << ": stripped module is broken!\n";
    138     return 1;
    139   }
    140 
    141   if (OutputAssembly) {
    142     Out.os() << *M;
    143   } else if (!CheckBitcodeOutputToConsole(Out.os(), true)) {
    144     WriteBitcodeToFile(M.get(), Out.os());
    145   }
    146 
    147   Out.keep();
    148 
    149   return 0;
    150 }
    151