[LLVMdev] how can I have LoopInfo in a module pass?

[Wenbin Zhang]

Thanks John, I modify my code to like this:

bool XXX::ModulePass(Module &M){
    ....
    LoopInfo &li = getAnalysis<LoopInfo>(fi);
    ....
}

Here fi is a Function* pointing to main().

Now when I run the pass, another error shows up:

AnalysisType& llvm::Pass::getAnalysisID(const llvm::PassInfo*, llvm::Function&) [with AnalysisType = llvm::LoopInfo]: Assertion `ResultPass && "Unable to find requested analysis info"' failed.

Did I miss something? Thanks!

Best,
--Wenbin
  ----- Original Message ----- 
  From: John Criswell 
  To: Wenbin Zhang 
  Cc: llvmdev at cs.uiuc.edu 
  Sent: Thursday, March 03, 2011 4:26 PM
  Subject: Re: [LLVMdev] how can I have LoopInfo in a module pass?


  On 3/3/11 3:09 PM, Wenbin Zhang wrote: 
    Hi all,
    I tried to have a LoopInfo object in a function pass, add addRequired<LoopInfo> in getAnalysisUsage, and then use getAnalysis<LoopInfo> in runOnFunction(). It worked OK.
    Now I want to have a module pass to traverse the functions, and similarly I want to have to loop information of the functions. When I did the above in runOnModule, and run the pass, the following error popped out:

    AnalysisType& llvm::Pass::getAnalysis() const [with AnalysisType = llvm::DominatorTree]: Assertion `Resolver && "Pass has not been inserted into a PassManager object!"' failed.

    Can anyone tell me the correct way to handle this in a module pass? Thanks a lot!

  LoopInfo is a FunctionPass, so you have to use getAnalysis<LoopInfo>(F) where F is a pointer to the function that you want analyzed.

  Note that LoopInfo, in this instance, will be re-run every time you call getAnalysis on it (this is a result of using a FunctionPass within a ModulePass).  Be sure to structure you code to only call getAnalysis<LoopInfo>(F) on each function just once, if possible.

  Also be sure that F is not a function declaration (i.e., a function with no body).

  -- John T.



    Best,
    --Wenbin

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