https://bugs.llvm.org/show_bug.cgi?id=41638
Bug ID: 41638
Summary: [X86] Avoid XOR $0, %al in parity generation
Product: libraries
Version: trunk
Hardware: PC
OS: Windows NT
Status: NEW
Severity: enhancement
Priority: P
Component: Backend: X86
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected], [email protected],
[email protected], [email protected]
As mentioned in https://reviews.llvm.org/D61230, the parity codegen in bool
vector xor reduction is generating "xor $0, $al" but it would be better to use
"test %al, %al" or "or %al, %al" or "and %al, %al" which gives a shorter
encoding since there would be no immediate.
define i1 @trunc_v2i64_v2i1(<2 x i64>) {
; SSE-LABEL: trunc_v2i64_v2i1:
; SSE: # %bb.0:
; SSE-NEXT: psllq $63, %xmm0
; SSE-NEXT: movmskpd %xmm0, %eax
; SSE-NEXT: xorb $0, %al
; SSE-NEXT: setnp %al
; SSE-NEXT: retq
;
; AVX-LABEL: trunc_v2i64_v2i1:
; AVX: # %bb.0:
; AVX-NEXT: vpsllq $63, %xmm0, %xmm0
; AVX-NEXT: vmovmskpd %xmm0, %eax
; AVX-NEXT: xorb $0, %al
; AVX-NEXT: setnp %al
; AVX-NEXT: retq
;
; AVX512BW-LABEL: trunc_v2i64_v2i1:
; AVX512BW: # %bb.0:
; AVX512BW-NEXT: vpsllq $63, %xmm0, %xmm0
; AVX512BW-NEXT: vptestmq %zmm0, %zmm0, %k0
; AVX512BW-NEXT: kmovd %k0, %eax
; AVX512BW-NEXT: andl $3, %eax
; AVX512BW-NEXT: xorb $0, %al
; AVX512BW-NEXT: setnp %al
; AVX512BW-NEXT: vzeroupper
; AVX512BW-NEXT: retq
;
; AVX512VL-LABEL: trunc_v2i64_v2i1:
; AVX512VL: # %bb.0:
; AVX512VL-NEXT: vpsllq $63, %xmm0, %xmm0
; AVX512VL-NEXT: vptestmq %xmm0, %xmm0, %k0
; AVX512VL-NEXT: kmovd %k0, %eax
; AVX512VL-NEXT: andl $3, %eax
; AVX512VL-NEXT: xorb $0, %al
; AVX512VL-NEXT: setnp %al
; AVX512VL-NEXT: retq
%a = trunc <2 x i64> %0 to <2 x i1>
%b = call i1 @llvm.experimental.vector.reduce.xor.v2i1(<2 x i1> %a)
ret i1 %b
}
declare i1 @llvm.experimental.vector.reduce.xor.v2i1(<2 x i1>)
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