[PATCH] D116039: [X86] Combine reduce (add (mul x, y)) to VNNI instruction.

[Roman Lebedev via Phabricator via llvm-commits]

lebedev.ri added inline comments.


================
Comment at: llvm/lib/Target/X86/X86ISelLowering.cpp:41790
+  // (dpbusd (zext a), (sext, b))
+  if ((IsFreeTruncation(Op0) && NumNonSignBits(Op0) <= 8) &&
+      (IsFreeTruncation(Op1) && NumNonSignBits(Op1) < 8))
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lebedev.ri wrote:
> lebedev.ri wrote:
> > This still does not handle the commutative variant.
> I'm not sure i follow.
> Why is this okay with negative numbers?
https://alive2.llvm.org/ce/z/WGxXrz vs https://alive2.llvm.org/ce/z/UbWhNv


Repository:
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CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D116039/new/

https://reviews.llvm.org/D116039