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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/Bitcode/ReaderWriter.h"
     18 #include "llvm/IR/LLVMContext.h"
     19 #include "llvm/IR/Module.h"
     20 #include "llvm/IR/Verifier.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/FileSystem.h"
     26 #include "llvm/Support/ManagedStatic.h"
     27 #include "llvm/Support/PrettyStackTrace.h"
     28 #include "llvm/Support/Signals.h"
     29 #include "llvm/Support/SourceMgr.h"
     30 #include "llvm/Support/SystemUtils.h"
     31 #include "llvm/Support/ToolOutputFile.h"
     32 using namespace llvm;
     33 
     34 static cl::list<std::string>
     35 InputFilenames(cl::Positional,
     36                cl::desc("<input bitcode files>"));
     37 
     38 static cl::opt<std::string>
     39 OutputFilename("o", cl::desc("Override output filename"), cl::init("-"),
     40                cl::value_desc("filename"));
     41 
     42 static cl::opt<bool>
     43 OutputAssembly("S",
     44                cl::desc("Write output as LLVM assembly"), cl::Hidden);
     45 
     46 namespace {
     47   class StripAttributes : public ModulePass {
     48   public:
     49     static char ID;
     50 
     51     StripAttributes() : ModulePass(ID) {
     52     }
     53 
     54     bool runOnFunction(Function &F) {
     55       // Remove any target-cpu and/or target-features attributes from each
     56       // Function or Function declaration.
     57       if (F.hasFnAttribute("target-cpu") ||
     58           F.hasFnAttribute("target-features")) {
     59 
     60         AttrBuilder B;
     61         B.addAttribute("target-cpu").addAttribute("target-features");
     62         AttributeSet ToStrip = AttributeSet::get(F.getContext(),
     63             AttributeSet::FunctionIndex, B);
     64         F.removeAttributes(AttributeSet::FunctionIndex, ToStrip);
     65         return true;
     66       }
     67       return false;
     68     }
     69 
     70     // We have to use a ModulePass, since a FunctionPass only gets run on
     71     // defined Functions (and not declared Functions).
     72     virtual bool runOnModule(Module &M) {
     73       bool Changed = false;
     74       for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
     75         Changed |= runOnFunction(*I);
     76       }
     77       return Changed;
     78     }
     79   };
     80 
     81   llvm::ModulePass * createStripAttributePass() {
     82     return new StripAttributes();
     83   }
     84 }
     85 
     86 
     87 char StripAttributes::ID = 0;
     88 static RegisterPass<StripAttributes> RPSA("StripAttributes",
     89     "Strip Function Attributes Pass");
     90 
     91 
     92 static inline std::unique_ptr<Module> LoadFile(const char *argv0,
     93                                                const std::string &FN,
     94                                                LLVMContext& Context) {
     95   SMDiagnostic Err;
     96   Module* Result = ParseIRFile(FN, Err, Context);
     97   if (Result) {
     98     return std::unique_ptr<Module>(Result);   // Load successful!
     99   }
    100 
    101   Err.print(argv0, errs());
    102   return std::unique_ptr<Module>();
    103 }
    104 
    105 
    106 int main(int argc, char **argv) {
    107   // Print a stack trace if we signal out.
    108   sys::PrintStackTraceOnErrorSignal();
    109   PrettyStackTraceProgram X(argc, argv);
    110 
    111   LLVMContext &Context = getGlobalContext();
    112   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    113   cl::ParseCommandLineOptions(argc, argv, "strip function attribute pass\n");
    114 
    115   std::string ErrorMessage;
    116 
    117   std::unique_ptr<Module> M(LoadFile(argv[0], InputFilenames[0], Context));
    118   if (M.get() == 0) {
    119     errs() << argv[0] << ": error loading file '"
    120            << InputFilenames[0] << "'\n";
    121     return 1;
    122   }
    123 
    124   // Perform the actual function attribute stripping.
    125   PassManager PM;
    126   PM.add(createStripAttributePass());
    127   PM.run(*M.get());
    128 
    129   std::string ErrorInfo;
    130   tool_output_file Out(OutputFilename.c_str(), ErrorInfo,
    131                        sys::fs::F_None);
    132   if (!ErrorInfo.empty()) {
    133     errs() << ErrorInfo << '\n';
    134     return 1;
    135   }
    136 
    137   if (verifyModule(*M)) {
    138     errs() << argv[0] << ": stripped module is broken!\n";
    139     return 1;
    140   }
    141 
    142   if (OutputAssembly) {
    143     Out.os() << *M;
    144   } else if (!CheckBitcodeOutputToConsole(Out.os(), true)) {
    145     WriteBitcodeToFile(M.get(), Out.os());
    146   }
    147 
    148   Out.keep();
    149 
    150   return 0;
    151 }
    152