[PATCH] D76984: [X86][SSE] Handle basic inversion of PTEST/TESTP operands (PR38522)

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon created this revision.
RKSimon added reviewers: craig.topper, spatel, lebedev.ri, gnzlbg.
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RKSimon updated this revision to Diff 253332.

sorry, git stash screwed up - fixed version shortly.


RKSimon added a comment.

fixed merge


PTEST/TESTP sets EFLAGS as:
TESTZ: ZF = (Op0 & Op1) == 0
TESTC: CF = (~Op0 & Op1) == 0
TESTNZC: ZF == 0 && CF == 0

If we are inverting the 0'th operand of a PTEST/TESTP instruction we can adjust the comparisons to correct handle the inversion implicitly.

Additionally, for "TESTZ" (ZF) cases, the allones case, PTEST(X,-1) can be simplified to PTEST(X,X).

We can expand this for the TEST(X,~Y) pattern and also handle KTEST/KORTEST as well but I wanted to get some initial feedback first.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D76984

Files:
  llvm/lib/Target/X86/X86ISelLowering.cpp
  llvm/test/CodeGen/X86/combine-ptest.ll
  llvm/test/CodeGen/X86/combine-testpd.ll
  llvm/test/CodeGen/X86/combine-testps.ll

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