[X86] Failure to merge VPTERNLOG patterns

[RKSimon]

Noticed on #163516

define <8 x i64> @foo(<8 x i64> %a, <8 x i64> %b, <8 x i64> %c) {
  %and.demorgan = or <8 x i64> %b, %a
  %and3.demorgan = or <8 x i64> %and.demorgan, %c
  %and3 = xor <8 x i64> %and3.demorgan, splat (i64 -1)
  ret <8 x i64> %and3
}

foo: # @foo
  vporq %zmm0, %zmm1, %zmm1
  vpternlogd $255, %zmm0, %zmm0, %zmm0 # zmm0 = -1
  vpternlogq $30, %zmm2, %zmm1, %zmm0 # zmm0 = zmm0 ^ (zmm1 | zmm2)
  retq

This should be able to fold to a single vpternlog instruction

VPTERNLOG construction is handled in X86ISelDAGToDAG.cpp

[llvmbot]

Hi!

This issue may be a good introductory issue for people new to working on LLVM. If you would like to work on this issue, your first steps are:

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If you have any further questions about this issue, don't hesitate to ask via a comment in the thread below.

[llvmbot]

@llvm/issue-subscribers-backend-x86

Author: Simon Pilgrim (RKSimon)

Noticed on #163516 ```ll define <8 x i64> @foo(<8 x i64> %a, <8 x i64> %b, <8 x i64> %c) { %and.demorgan = or <8 x i64> %b, %a %and3.demorgan = or <8 x i64> %and.demorgan, %c %and3 = xor <8 x i64> %and3.demorgan, splat (i64 -1) ret <8 x i64> %and3 } ``` ```asm foo: # @foo vporq %zmm0, %zmm1, %zmm1 vpternlogd $255, %zmm0, %zmm0, %zmm0 # zmm0 = -1 vpternlogq $30, %zmm2, %zmm1, %zmm0 # zmm0 = zmm0 ^ (zmm1 | zmm2) retq ``` This should be able to fold to a single vpternlog instruction

VPTERNLOG construction is handled in X86ISelDAGToDAG.cpp

[llvmbot]

@llvm/issue-subscribers-good-first-issue

Author: Simon Pilgrim (RKSimon)

Noticed on #163516 ```ll define <8 x i64> @foo(<8 x i64> %a, <8 x i64> %b, <8 x i64> %c) { %and.demorgan = or <8 x i64> %b, %a %and3.demorgan = or <8 x i64> %and.demorgan, %c %and3 = xor <8 x i64> %and3.demorgan, splat (i64 -1) ret <8 x i64> %and3 } ``` ```asm foo: # @foo vporq %zmm0, %zmm1, %zmm1 vpternlogd $255, %zmm0, %zmm0, %zmm0 # zmm0 = -1 vpternlogq $30, %zmm2, %zmm1, %zmm0 # zmm0 = zmm0 ^ (zmm1 | zmm2) retq ``` This should be able to fold to a single vpternlog instruction

VPTERNLOG construction is handled in X86ISelDAGToDAG.cpp

[kimsh02]

@RKSimon Hi, do I need an x86 cpu to take this?

[RKSimon]

@RKSimon Hi, do I need an x86 cpu to take this?

Probably not, but you should be familiar with how VPTERNLOG works

[yichi170]

Hi @RKSimon, I would like to give it a try. Can I be assigned this issue?