[PATCH] D25276: [LoopVectorizer] Interleaved-mem-accesses analysis and getPtrStride

[Dorit Nuzman via llvm-commits]

dorit added inline comments.


================
Comment at: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp:5872
+        continue;
+      Value *Ptr = getPointerOperand(Member);
+      int Stride = getPtrStride(PSE, Ptr, TheLoop, Strides, /*Assume=*/false,
----------------
dorit wrote:
> sbaranga wrote:
> > I think there is another case here when we don't need to check the wrapping: if the group has the first and last pointers, and we know they both don't wrap.
> > 
> > We should be able to apply this for versioning later and have at most two no-wrap checks per interleaved group.
> So, trying to summarize:
> 1) Initial check with Assume=true, ShouldCheckWrap=false;
> 2) Revisit only groups with gaps as follows: 
> - if first and last elements are accessed: skip further checking.
> - otherwise – check the first and last pointers of the group with Assume=false (for now), ShouldCheckWrap=true;
> 
> Silviu, is that what you meant?
> 
3 and 4 above were meant to be sub-bullets of item 2...:

1.Initial check with Assume=true, ShouldCheckWrap=false;
2.Revisit only groups with gaps as follows:
   - if first and last elements are accessed: skip further checking.
   - otherwise – check the first and last pointers of the group with Assume=false (for now), ShouldCheckWrap=true;



https://reviews.llvm.org/D25276