[llvm-dev] Question about using LoopAccessLegacyAnalysis

Kewen Meng via llvm-dev llvm-dev at lists.llvm.org
Wed Feb 7 09:49:32 PST 2018

Hi LLVM community,

I am writing a custom pass for analyzing the dependence information for the memory access within a loop. I found “LoopAccessLegacyAnalysis” class useful, however I m not able to obtain information from that pass. Here is what I did to get the information:

// require pass 
virtual void getAnalysisUsage(AnalysisUsage &AU) const

// processing
virtual bool runOnFunction(Function &F) {
         LoopInfo &li = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
         LoopAccessLegacyAnalysis &lala = getAnalysis<LoopAccessLegacyAnalysis>();

         for(LoopInfo::iterator lp = li.begin(); lp != li.end(); lp++)
             Loop *loop = *lp;
             const LoopAccessInfo &lai = lala.getInfo(loop);
	      // need help here
	      // I can’t get any information from the LoopAccessInfo instance.
	      errs()<<lai.getNumLoads(); // return 0

// register
static RegisterPass<SkeletonPass> X("test", "test for using the existing pass",

I must be missing something important. Any response would be greatly appreciated!


Best regards,

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