Re: [PATCH 1/n, i386]: Merge SSE and AVX patterns using "enable" attribute.

[Uros Bizjak <ubizjak at gmail dot com>]

On Wed, Apr 6, 2011 at 1:12 PM, Kirill Yukhin <kirill.yukhin@gmail.com> wrote:

> Nice patch. But I have two question:
> - What will be with future extensions? E.g. what if `avxXX` will appear, do
> you think that common parts with previous extentions should be shrinked in
> that way?

The patch in fact mixes two somehow orthogonal approaches:

- uses "enable" attribute to merge the same SSE and AVX patterns that
differ only in the number of operands.

- introduces conditional vector float modes.

So, if there is AVXv2 that adds another mode, this mode can be added
to VF mode iterator as a mode that depends on TARGET_AVX2.  More
likely, there will be new three-operand instructions and these will be
added with TARGET_AVX2 insn constraint. If there are no corresponding
two-operand instructions, then "enabled" attribute won't come into
play.

> - Are you replaced with that fancy method all the insn? E.g. adds with
> saturation are not touched by the patch (and I believe can be shrinked as
> well):

I did say that "This patch changes i386.md, "Parallel floating point
arithmetic" and
"Parallel floating point comparisons" sections of sse.md." in the
original patch submission, didn't I ? ;)

I'm sure that in addition to saturated adds, there are plenty of other
opportunities for "enabled" attribute. These will be attacked in
further patches - btw - you are more than welcome to look for them in
the .md files; candidate patterns are prefixed with avx_ .

Uros.