https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114514
--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
For non constant clang produces:
```
signedshiftright:
movzbl %dil, %eax
movd %eax, %xmm1
psrlw %xmm1, %xmm0
pcmpeqd %xmm2, %xmm2
psrlw %xmm1, %xmm2
movdqa .LCPI0_0(%rip), %xmm3 # xmm3 =
[32896,32896,32896,32896,32896,32896,32896,32896]
psrlw %xmm1, %xmm3
psrlw $8, %xmm2
punpcklbw %xmm2, %xmm2 # xmm2 =
xmm2[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
pshuflw $0, %xmm2, %xmm1 # xmm1 = xmm2[0,0,0,0,4,5,6,7]
pshufd $0, %xmm1, %xmm1 # xmm1 = xmm1[0,0,0,0]
pand %xmm1, %xmm0
pxor %xmm3, %xmm0
psubb %xmm3, %xmm0
retq
unsignedshiftrtight:
movzbl %dil, %eax
movd %eax, %xmm1
psrlw %xmm1, %xmm0
pcmpeqd %xmm2, %xmm2
psrlw %xmm1, %xmm2
psrlw $8, %xmm2
punpcklbw %xmm2, %xmm2 # xmm2 =
xmm2[0,0,1,1,2,2,3,3,4,4,5,5,6,6,7,7]
pshuflw $0, %xmm2, %xmm1 # xmm1 = xmm2[0,0,0,0,4,5,6,7]
pshufd $0, %xmm1, %xmm1 # xmm1 = xmm1[0,0,0,0]
pand %xmm1, %xmm0
retq
```
I am not sure which way is faster here though.
