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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/LegacyPassManager.h"
     20 #include "llvm/IR/Module.h"
     21 #include "llvm/IR/Verifier.h"
     22 #include "llvm/IRReader/IRReader.h"
     23 #include "llvm/Pass.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     virtual void getAnalysisUsage(llvm::AnalysisUsage &AU) const override {
     55       AU.setPreservesAll();
     56     }
     57 
     58     bool runOnFunction(Function &F) {
     59       // Remove any target-cpu and/or target-features attributes from each
     60       // Function or Function declaration.
     61       if (F.hasFnAttribute("target-cpu") ||
     62           F.hasFnAttribute("target-features")) {
     63 
     64         AttrBuilder B;
     65         B.addAttribute("target-cpu").addAttribute("target-features");
     66         AttributeSet ToStrip = AttributeSet::get(F.getContext(),
     67             AttributeSet::FunctionIndex, B);
     68         F.removeAttributes(AttributeSet::FunctionIndex, ToStrip);
     69         return true;
     70       }
     71       return false;
     72     }
     73 
     74     // We have to use a ModulePass, since a FunctionPass only gets run on
     75     // defined Functions (and not declared Functions).
     76     virtual bool runOnModule(Module &M) {
     77       bool Changed = false;
     78       for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
     79         Changed |= runOnFunction(*I);
     80       }
     81       return Changed;
     82     }
     83   };
     84 
     85   llvm::ModulePass * createStripAttributePass() {
     86     return new StripAttributes();
     87   }
     88 }
     89 
     90 
     91 char StripAttributes::ID = 0;
     92 static RegisterPass<StripAttributes> RPSA("StripAttributes",
     93     "Strip Function Attributes Pass");
     94 
     95 
     96 static inline std::unique_ptr<Module> LoadFile(const char *argv0,
     97                                                const std::string &FN,
     98                                                LLVMContext& Context) {
     99   SMDiagnostic Err;
    100   std::unique_ptr<Module> Result = parseIRFile(FN, Err, Context);
    101   if (Result) {
    102     return Result;   // Load successful!
    103   }
    104 
    105   Err.print(argv0, errs());
    106   return std::unique_ptr<Module>();
    107 }
    108 
    109 
    110 int main(int argc, char **argv) {
    111   // Print a stack trace if we signal out.
    112   sys::PrintStackTraceOnErrorSignal(argv[0]);
    113   PrettyStackTraceProgram X(argc, argv);
    114 
    115   LLVMContext Context;
    116   llvm_shutdown_obj Y;  // Call llvm_shutdown() on exit.
    117   cl::ParseCommandLineOptions(argc, argv, "strip function attribute pass\n");
    118 
    119   std::string ErrorMessage;
    120 
    121   std::unique_ptr<Module> M(LoadFile(argv[0], InputFilenames[0], Context));
    122   if (M.get() == 0) {
    123     errs() << argv[0] << ": error loading file '"
    124            << InputFilenames[0] << "'\n";
    125     return 1;
    126   }
    127 
    128   // Perform the actual function attribute stripping.
    129   legacy::PassManager PM;
    130   PM.add(createStripAttributePass());
    131   PM.run(*M.get());
    132 
    133   std::error_code EC;
    134   tool_output_file Out(OutputFilename.c_str(), EC,
    135                        sys::fs::F_None);
    136   if (EC) {
    137     errs() << EC.message() << '\n';
    138     return 1;
    139   }
    140 
    141   if (verifyModule(*M)) {
    142     errs() << argv[0] << ": stripped module is broken!\n";
    143     return 1;
    144   }
    145 
    146   if (OutputAssembly) {
    147     Out.os() << *M;
    148   } else if (!CheckBitcodeOutputToConsole(Out.os(), true)) {
    149     WriteBitcodeToFile(M.get(), Out.os());
    150   }
    151 
    152   Out.keep();
    153 
    154   return 0;
    155 }
    156