[PATCH] D91255: [AArch64] Rearrange (dup(sext/zext)) to (sext/zext(dup))

Wed Nov 11 07:00:00 PST 2020

SjoerdMeijer added inline comments.

================
Comment at: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp:10584-10586
+
+      // TODO Why can this sometimes fail?
+      if(isa<Instruction>(&Shuffle->getOperandUse(0)))
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NickGuy wrote:
> In a number of tests, this line is hit more than a few times. Only 1 of which it fails on. Using .dump() to try and identify why didn't help, as it appears to be the same style as the others that pass (e.g. %tmp3 = sext <8 x i8> %arg to <8 x i16>)
> If anyone can provide insight to this, I would greatly appreciate it :)
what do you mean by fail? I guess that's a segfault?
I guess you need to make sure it is an instruction first with dyn_cast, then you check its operands and uses. 

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  https://reviews.llvm.org/D91255/new/

https://reviews.llvm.org/D91255