Question

我想插入一个计数器来记录基本块执行的次数。

我采取的步骤：

我编写了名为BlockProfiling.cpp

我用以下代码编译：

$ g++ -c BlockProfiling.cpp _i/usr/local/include `llvm-config --cxxflag`

它生成一个名为BlockPrpfiling.o

我跑：

$ g++ -shared -o BlockProfiling.so BlockProfiling.o -L/usr/local/lib `llvm-config --ldflags -libs`

它会生成一个名为BlockProfiling.so

我用它来检测我的文件test.bc并生成test.bb.bc：

$opt -load=./BlockProfiling.so -insert-bb-profling test.bc -o test.bb.bc

我使用llvm-diff确认已完成。

但是当我使用lli执行test.bb.bc时，会出现一个错误：

LLVM错误：程序使用了无法解析的外部函数'llvm_start_func_profiling'！

任何解决方案？

llvm版本是3.3，这是我的代码：

namespace{
struct BlockProfiler: public ModulePass{
    static char ID;
    BlockProfiler():ModulePass(ID) {
        initializeBlock ProfilerPass(*Registry::getPassRegistry());
    }

    virtual bool runOnModule(Module &M);
};  //end of function profiling pass

}  //end of namespace

char BlockProfiler::ID = 0 ;
INITIALIZE_PASS(BlockProfiler, "insert-block-profiling",
    "Insert instrumentation for profiling", false, false )

ModulePass *llvm::createBlockProfilerPass() {return new BlockProfiler() ;  }


//static RegisterPass<BlockProfilerPass> Y("insert-block-profiling", 
                                           "Insert instrumentation for block profiling");

bool BlockProfiler::runOnModule(Module &M){
Function *Main = M.getFunction("main") ;
if(Main == 0)
{
    errs()<<" WARING: cannot insert block profiling into a module"
        <<" with no main function. \n" ;
    return false ; // no main, no instrumentation, and no modify
}

unsigned NumBlocks = 0;
for(Module::iterator I = M.begin(), E = M.end(); I != E ; ++I)
    NumBlocks += I->size(); 

Type *ATy = ArrayType::get(Type::getInt32Ty(M.getContext()), NumBlocks) ;
GlobalVariable *Counters = 
    new GlobalVariable(M, ATy, false, GlobalValue::InternalLinkage,
        Constant::getNullValue(ATy), "BlockProCounters") ;

//Instrument all of the blocks
    unsigned i = 0;
    for(Module::iterator I = M.begin(), E = M.end(); I != E; ++I){
        for(Function::iterator BB = I->begin(), E = I->end() ; BB != E; ++BB )
            //Insert counter at the start of the block
            IncrementCounterInBlock(BB, i++, Counters);
    }

    //add the initialization call to main
    InsertProfilingInitCall(Main, "llvm_start_block_profiling", Counters); 
    return true;
}

基本块检测

0 个答案: