Re: Vector registers on MIPS arch

[Ilya Enkovich <enkovich dot gnu at gmail dot com>]

2016-04-02 3:32 GMT+03:00 David Guillen Fandos <david@davidgf.net>:
> Hello there!
>
> I'm trying to add some vector registers to a MIPS arch (32 bit). This
> arch has 32 x 128 bit registers that can essentially be seen as V4SF.
> So far I'm using this test:
>
> volatile float foo __attribute__ ((vector_size (16)));
> volatile float bar __attribute__ ((vector_size (16)));
>
> int main() {
>         foo = foo + bar;
> }
>
> Which produces the right SSE/AVX instructions for x86 but fails on my
> mips cross compiler with my modifications.
> The modifications I did so far are:
>
>  - Add 32 new regsiters, adding a register class, updating/adding bit
> fields, updating also other macros that deal with reg allocation (like
> caller saved and stuff). Also incremented the first pseudo reg value.
>
>  - Add 3 define_insn that load, store and add vectors.
>
>  - Tweak some things here and there to let the compiler know about the
> V4SF type being available.
>
> So far the compiler goes back to scalar code, not working properly at
> the veclower pass. My test.c.123t.veclower21 looks like:
>
>   <bb 2>:
>   foo.0_2 ={v} foo;
>   bar.1_3 ={v} bar;
>   _6 = BIT_FIELD_REF <foo.0_2, 32, 0>;
>   _7 = BIT_FIELD_REF <bar.1_3, 32, 0>;
>   _8 = _6 + _7;
>   _9 = BIT_FIELD_REF <foo.0_2, 32, 32>;
>   _10 = BIT_FIELD_REF <bar.1_3, 32, 32>;
>   _11 = _9 + _10;
>   _12 = BIT_FIELD_REF <foo.0_2, 32, 64>;
>   _13 = BIT_FIELD_REF <bar.1_3, 32, 64>;
>   _14 = _12 + _13;
>   _15 = BIT_FIELD_REF <foo.0_2, 32, 96>;
>   _16 = BIT_FIELD_REF <bar.1_3, 32, 96>;
>   _17 = _15 + _16;
>   foo.2_4 = {_8, _11, _14, _17};
>   foo ={v} foo.2_4;
>   return 0;
>
>
> Any ideas on what I'm missing and/or how to further debug this? I don't
> really want autovectorization, just to be able to use vec registers
> "manually".

Hi.

Can't say for sure since you didn't attach your patch.  But vector
lowering happens for a vector statement which doesn't have corresponding
entry in optab.  You must ensure your templates have proper names to
get them added to optabs.

Thanks,
Ilya

>
> Thanks!
> David
>