[PATCH] D108725: [AArch64][GlobalISel] Implement custom legalization for s32/s64 G_FCOPYSIGN

[Jessica Paquette via Phabricator via llvm-commits]

paquette added a comment.

Not quite.

We get the following for s32 with G_MERGE_VALUES:

  legalize_s32:
  	adrp	x8, .LCPI0_0
  	mov	v0.s[1], v0.s[0]
  	mov	v1.s[1], v0.s[0]
  	ldr	q2, [x8, :lo12:.LCPI0_0]
  	mov	v0.s[2], v0.s[0]
  	mov	v0.s[3], v0.s[0]
  	mov	v1.s[2], v0.s[0]
  	mov	v1.s[3], v0.s[0]
  	bit	v0.16b, v1.16b, v2.16b
  	ret

Meanwhile, with SDAG we get

  	movi	v2.4s, #128, lsl #24 ; We should emit the constant like this, but we don't have that optimization
  	bit	v0.16b, v1.16b, v2.16b
  	ret

We can probably change the selector code to recognize the pattern though. Using G_INSERT_VECTOR_ELT is only slightly better.


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https://reviews.llvm.org/D108725