[PATCH] D27518: Moving isComplex decision to TTI

[Michael Kuperstein via Phabricator via llvm-commits]

mkuper added a comment.

What I'm saying is that you have this code in getAddressAccessComplexity():

  const SCEVAddRecExpr *AddRec = dyn_cast<SCEVAddRecExpr>(SE->getSCEV(Ptr));
  if (!AddRec)
    return AddressInfo;
  
  AddressInfo.isStrided = true;
  
  // Get Step Recurrence.
  AddressInfo.Step = AddRec->getStepRecurrence(*SE);
  return AddressInfo;

So, basically, the logic right now is:

1. If we don't have a SCEV for the pointer, or have a SCEV which isn't an AddRec, return a struct with isStrided == false.
2. If we have a SCEV, and it's an AddRec, return a struct with isStrided == true, and a Step.

What I'm saying is that you could replace this with "If we don't have a SCEVAddRecExpr for the pointer return null, otherwise return the SCEV", and pass the result of that into getAddressComputationCost(). Then, if getAddressComputationCost() doesn't get a SCEV, it knows the access isn't strided. If it does get a SCEV, it knows it's strided, and can call getStepRecurrence to get the Step.

Am I missing something?


https://reviews.llvm.org/D27518