填充LLVM CloneFunction VMAP [英] Filling the LLVM CloneFunction VMAP

问题描述

我想编写一些代码，给定LLVM函数F，该代码在同一模块中创建一个精确的副本(因此可以在以后保留原始副本的情况下操纵该副本).我想用CloneFunctionInto方法做到这一点.

I want to write some code that, given an LLVM function F, creates an exact copy in the same module (so the copy can be manipulated later while preserving the original). I want to do this with the CloneFunctionInto method.

我当前的尝试涉及尝试将每个(新arg，旧arg)对插入VMap.以前，我曾尝试插入未初始化的VMap，然后将其反过来放置.令人印象深刻的是，所有这三个都导致了完全相同的错误消息:

My current attempt involves trying to insert each (new arg,old arg) pair into the VMap. Previously I've tried inserting an uninitialised VMap and putting the pair the other way round. Impressively, all 3 have resulted in the exact same error message:

断言`VMap.count(& I)&& 未指定从源参数的映射！"失败.

Assertion `VMap.count(&I) && "No mapping from source argument specified!"' failed.

//F and S are defined higher up in the code
FunctionType *FType = F->getFunctionType();
Function *new_F = cast<Function>(M->getOrInsertFunction(S,FType));
std::vector<Type*> ArgTypes;
ValueToValueMapTy VMap;
Function::arg_iterator old_args = F->arg_begin();
for (Function::arg_iterator new_args = new_F->arg_begin(), new_args_end = new_F->arg_end();new_args != new_args_end; new_args++) {
  std::pair<Value*,Value*> pair(&*new_args,&*old_args);
  VMap.insert(pair);
  if (VMap.count(&*new_args)>0) {
   errs().write_escaped("Mapping added") << '\n';
  }
  old_args++;
 }
 SmallVector<ReturnInst*, 8> Returns;
 CloneFunctionInto(new_F, F, VMap, false, Returns, "_new", 0, 0);

在使用中，已添加映射"消息被打印正确的次数(即每个参数一次)，所以我真的不确定错误在哪里.

In use, the 'mapping added' message is printed the correct number of times (i.e. once for each argument), so I'm really unsure where the error is.

推荐答案

当您只想克隆一个函数时，可以使用CloneFunction代替CloneFunctionInto.

You can use CloneFunction instead of CloneFunctionInto when you just want to clone a function.

还CloneFunction向您展示了如何处理ValueToValueMap进行克隆:

Also CloneFunction shows you how to handle a ValueToValueMap for cloning:

来自CloneFunction.cpp:

00223 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
00224                               bool ModuleLevelChanges,
00225                               ClonedCodeInfo *CodeInfo) {
00226   std::vector<Type*> ArgTypes;
00227 
00228   // The user might be deleting arguments to the function by specifying them in
00229   // the VMap.  If so, we need to not add the arguments to the arg ty vector
00230   //
00231   for (const Argument &I : F->args())
00232     if (VMap.count(&I) == 0) // Haven't mapped the argument to anything yet?
00233       ArgTypes.push_back(I.getType());
00234 
00235   // Create a new function type...
00236   FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
00237                                     ArgTypes, F->getFunctionType()->isVarArg());
00238 
00239   // Create the new function...
00240   Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());
00241 
00242   // Loop over the arguments, copying the names of the mapped arguments over...
00243   Function::arg_iterator DestI = NewF->arg_begin();
00244   for (const Argument & I : F->args())
00245     if (VMap.count(&I) == 0) {     // Is this argument preserved?
00246       DestI->setName(I.getName()); // Copy the name over...
00247       VMap[&I] = &*DestI++;        // Add mapping to VMap
00248     }
00249 
00250   if (ModuleLevelChanges)
00251     CloneDebugInfoMetadata(NewF, F, VMap);
00252 
00253   SmallVector<ReturnInst*, 8> Returns;  // Ignore returns cloned.
00254   CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
00255   return NewF;
00256 }

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