Question

我正在使用llvm 4.0。我需要挂钩一个函数，其中参数是IR中的局部变量之一，例如我想将％10值传递给函数。我知道如何挂钩一个函数。以下是我的代码：

hookFunc2 = M.getOrInsertFunction("funcName", Type::getVoidTy(M.getContext()),Type::getInt8PtrTy(M.getContext()),NULL);    
hook1= cast<Function>(hookFunc2);
IRBuilder <> builder1(a); //where a is the basic block pointer
BasicBlock::iterator BC = a->begin();
builder1.SetInsertPoint(&(*BC));
Value* args = builder1.CreateGlobalStringPtr(%10); //this is wrong.what should be here instead of %10? I want %10 value.
builder1.CreateCall(hook1, args)

Answer 1

感谢您的回复。我知道了。代码是％10 = getelementptr inbounds [10000 x i8]，[10000 x i8] *％line，i32 0，i32 0 ％11 =加载％struct._IO_FILE *，％struct._IO_FILE **％fp，对齐8 ％12 =调用i8 * @fgets（i8 *％10，i32 10000，％struct._IO_FILE *％11）

我可以通过使用

获取fgets 1参数来获得％10

   CallInst abc = cast<CallInst>(&(*i)); //where i is the instruction pointer where fgets is called.
   Value* args = abc->getOperand(0);
   builder1.CreateCall(hook1, args)

将局部变量传递给函数llvm

1 个答案: