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[X86][SSE] Add test showing missed opportunity to combine to pshuflw

We are combining shuffles to bit shifts before unary permutes, which means we can't fold loads plus the destination register is destructive

llvm-svn: 306976
This commit is contained in:
Simon Pilgrim 2017-07-02 12:56:10 +00:00
parent 1032df3c54
commit 66c4c00993

View File

@ -445,6 +445,24 @@ define <16 x i8> @combine_pshufb_not_as_pshufw(<16 x i8> %a0) {
ret <16 x i8> %res1
}
; TODO - we could fold the load if we lowered to pshuflw instead.
define <16 x i8> @combine_vpshufb_as_pshuflw_not_pslld(<16 x i8> *%a0) {
; SSE-LABEL: combine_vpshufb_as_pshuflw_not_pslld:
; SSE: # BB#0:
; SSE-NEXT: movdqa (%rdi), %xmm0
; SSE-NEXT: pslld $16, %xmm0
; SSE-NEXT: retq
;
; AVX-LABEL: combine_vpshufb_as_pshuflw_not_pslld:
; AVX: # BB#0:
; AVX-NEXT: vmovdqa (%rdi), %xmm0
; AVX-NEXT: vpslld $16, %xmm0, %xmm0
; AVX-NEXT: retq
%res0 = load <16 x i8>, <16 x i8> *%a0, align 16
%res1 = call <16 x i8> @llvm.x86.ssse3.pshuf.b.128(<16 x i8> %res0, <16 x i8> <i8 undef, i8 undef, i8 0, i8 1, i8 undef, i8 undef, i8 4, i8 5, i8 undef, i8 undef, i8 undef, i8 undef, i8 undef, i8 undef, i8 undef, i8 undef>)
ret <16 x i8> %res1
}
define <16 x i8> @combine_pshufb_as_unary_unpcklbw(<16 x i8> %a0) {
; SSE-LABEL: combine_pshufb_as_unary_unpcklbw:
; SSE: # BB#0: