[PATCH] D25987: [X86] New pattern to generate PSUBUS from SELECT

[Yulia Koval via Phabricator via llvm-commits]

yulia_koval updated this revision to Diff 85883.
yulia_koval added a comment.
Herald added a subscriber: igorb.

I updated the patch to trunk, because test output changed due to https://reviews.llvm.org/rL292479 optimization. I failed to find a better check, based on TLI.isLegal.., because it doesn't requires exact type. For example, in case of SSE4.1, isOperationLegalOrCustom(MIN, v8i32) returns false and disables the optimization. However, the transformation works fine as the illegal operation is split into two v4i32 operations. The hasSSE41 check is sufficient, because it includes both v8i16 and v4i32 for each integer type. i8(SSE hass i8 based umin) can't be used in this optimisation, because the ExtType is always larger then psubus type and can be minimum i16.


https://reviews.llvm.org/D25987

Files:
  lib/Target/X86/X86ISelLowering.cpp
  test/CodeGen/X86/psubus.ll

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