On Mar 22, 2007, at 11:43 AM, Bill Wendling wrote:
> +We should compile this:
> +
> +#include <xmmintrin.h>
> +
> +void foo(__m128i *A, __m128i *B) {
> + *A = _mm_sll_epi16 (*A, *B);
> +}
> +
> +to:
> +
> +_foo:
> + subl $12, %esp
> + movl 16(%esp), %edx
> + movl 20(%esp), %eax
> + movdqa (%edx), %xmm1
> + movdqa (%eax), %xmm0
> + psllw %xmm0, %xmm1
> + movdqa %xmm1, (%edx)
> + addl $12, %esp
> + ret
> +
> +not:
> +
> +_foo:
> + movl 8(%esp), %eax
> + movdqa (%eax), %xmm0
> + #IMPLICIT_DEF %eax
> + pinsrw $2, %eax, %xmm0
> + xorl %ecx, %ecx
> + pinsrw $3, %ecx, %xmm0
> + pinsrw $4, %eax, %xmm0
> + pinsrw $5, %ecx, %xmm0
> + pinsrw $6, %eax, %xmm0
> + pinsrw $7, %ecx, %xmm0
> + movl 4(%esp), %eax
> + movdqa (%eax), %xmm1
> + psllw %xmm0, %xmm1
> + movdqa %xmm1, (%eax)
> + ret
This looks like a *serious* SSE performance bug, not a missing
feature. Bill, can you look into this? Evan, can you help him if
needed?
Thanks,
-Chris
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