Re: [PATCH, i386]: Vectorize copysign for x86

[Richard Guenther <richard dot guenther at gmail dot com>]

2009/7/15 Uros Bizjak <ubizjak@gmail.com>:
> On 07/14/2009 07:17 PM, Uros Bizjak wrote:
>
>> Attached patch enables vectorization of copysign function for x86 SSE
>> targets.
>
> Actually, since vectorized inverted sign bit mask value, created with
> ix86_build_signbit_mask exactly represents inverted value of the vectorized
> sign bits that is already available in a register, i.e. for SFmode:
>
> ~0x8000800080008000 = 0x7FFF7FFF7FFF7FFF
>
> ?we can reuse non-inverted value by using and-not SSE instruction.
>
> copysign loop then vectorizes to:
>
> ? ?movaps ? ?.LC0(%rip), %xmm1
> .L3:
> ? ?movaps ? ?%xmm1, %xmm0
> ? ?movaps ? ?b(%rax), %xmm2
> ? ?andnps ? ?a(%rax), %xmm0
> ? ?andps ? ?%xmm1, %xmm2
> ? ?orps ? ?%xmm2, %xmm0
> ? ?movaps ? ?%xmm0, r(%rax)
> ? ?addq ? ?$16, %rax
> ? ?cmpq ? ?$64, %rax
> ? ?jne ? ?.L3
>
> ? ?.section ? ?.rodata.cst16,"aM",@progbits,16
> ? ?.align 16
> .LC0:
> ? ?.long ? ?2147483648
> ? ?.long ? ?2147483648
> ? ?.long ? ?2147483648
> ? ?.long ? ?2147483648
> ? ?.align 16

Generating these kind of constants may be smaller and faster if
we use some arithmetic tricks.  Do we have some generic routine
that could be used to materialize special constants?

Richard.

>
> 2009-07-15 ?Uros Bizjak <ubizjak@gmail.com>
>
> ? ?* config/i386/sse.md (copysign<mode>3): Use "and-not" SSE instruction
> ? ?instead of "and" with inverted sign bit mask value. ?Use
> ? ?"nonimmediate_operand" for operand 1 and operand 2 predicate.
> ? ?Allocate registers only for operand 4 and operand 5.
>
> Patch was bootstrapped and regression tested on x86_64-pc-linux-gnu {,-m32}.
> Patch was committed to mainline SVN.
>
> Uros.
>