llvm dev - Feb 2018 - Question about using LoopAccessLegacyAnalysis

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
     {
          AU.addRequired<LoopInfoWrapperPass>();
          AU.addRequired<LoopAccessLegacyAnalysis>();
          AU.setPreservesAll();
     }

// 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",
                                     “false",
                                     “false”);


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

Thanks,
Kewen




Best regards,
Kewen