[LLVMdev] about writing a functionpass requiring a modulepass

[Devang Patel]

On May 30, 2011, at 2:15 AM, Qingan Li wrote:

> 
> 
> ---------- Forwarded message ----------
> From: Qingan Li <ww345ww at gmail.com>
> Date: 2011/5/30
> Subject: 
> To: llvmdev at cs.uiuc.edu
> 
> 
> 
> Hi,
> 
> I wrote an analysis pass, myPass, inherited from both  ModulePass and ProfileInfo, and this pass requires the CallGraph, i.e.,
>   class myPass : public ModulePass, public ProfileInfo { ...};
>   void myPass::getAnalysisUsage(AnalysisUsage &AU) const {
>   AU.addRequired<CallGraph>();
>   AU.setPreservesAll();
> }
> 
> Then, I assumes the UnreachableBlockElim (inherited from FunctionPass) requires myPass, by revising the related function as follows:
>  UnreachableBlockElim::getAnalysisUsage(AnalysisUsage &AU) const {	
>       AU.addPreserved<DominatorTree>();
>       AU.addPreserved<ProfileInfo>();
> 	    AU.addRequired<StaticProfilePass>();
> 	  
>     }
> 
> Then, i built it, it is OK. I went on to run it. It failed with a segment error.
> By debugging, it is found that in the following code from PMTopLevelManager::schedulePass(Pass *P),
>         const PassInfo *PI = PassRegistry::getPassRegistry()->getPassInfo(*I);
>         AnalysisPass = PI->createPass();
> 
> When this manager search for the CallGraph reqiured by myPass ( in the failing trace , Pass *P is myPass), the return value of PassRegistry::getPassInfo(const void *TI) is NULL, thus the following dereference of PI is invalid.

This may be a limitation of pass manager. Please file a bug report with a reproducible test case. Thanks!
-
Devang


> I am using llvm 2.9, which is download from http://llvm.org/releases/.
> Could anybody help me?
> 
> 
> 
> -- 
> Best regards,
> 
> Li Qingan
> 
> 
> 
> 
> -- 
> Best regards,
> 
> Li Qingan
> 
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20110531/11649660/attachment.html>