[PATCH] D34009: [Power9] Exploit vector integer extend instructions when indices aren't correct

[Zaara Syeda via Phabricator via llvm-commits]

syzaara added inline comments.


================
Comment at: lib/Target/PowerPC/PPCISelLowering.cpp:11332
+  int OutputSize = N->getValueType(0).getScalarSizeInBits();
+  if (InputSize + OutputSize == 40)
+    TgtElemArrayIdx = 0;
----------------
stefanp wrote:
> I realize that you are trying to check for the 
> byte -> word 
> case with this if statement. 
> However, is it possible to also catch word -> byte too? 
> You may have thought of this already and filtered out unwanted cases earlier up... I don't know. I just wanted to bring this to your attention in case it might be a problem.
Actually, I think it's okay since things like word -> byte would fail the isSExtOfVecExtract pattern matching so we wouldn't reach this far.


https://reviews.llvm.org/D34009