[Mesa-dev] [PATCH 3/4] i965/vec4: Combine all the math emitters.

[Francisco Jerez]

Kenneth Graunke <kenneth at whitecape.org> writes:

> On Wednesday, November 12, 2014 09:57:30 PM Matt Turner wrote:
>> On Wed, Nov 12, 2014 at 9:35 PM, Kenneth Graunke <kenneth at whitecape.org> 
> wrote:
>> > +vec4_visitor::emit_math(enum opcode opcode,
>> > +                       dst_reg dst, src_reg src0, src_reg src1)
>> 
>> I think you can make the arguments const references too?
>
> Yeah.  I've changed the prototype to:
>
> void emit_math(enum opcode opcode, const dst_reg &dst, const src_reg &src0,
>                const src_reg &src1 = src_reg());
>
> It also meant changing the first few lines to:
>
>    vec4_instruction *math =
>       emit(opcode, dst, fix_math_operand(src0), fix_math_operand(src1))
>
> since "src0 = fix_math_operand(src0)" doesn't work with "const src_reg &".
>
>> > +   if (brw->gen == 6 && dst.writemask != WRITEMASK_XYZW) {
>> > +      /* MATH on Gen6 must be align1, so we can't do writemasks. */
>> > +      math->dst = dst_reg(this, glsl_type::vec4_type);
>> > +      math->dst.type = dst.type;
>> > +      math->dst.writemask = WRITEMASK_XYZW;
>> 
>> I don't think you need to set the writemask (XYZW is the default).
>
> I do, actually - it's guaranteed to not be XYZW at this point.  The caller 
> passed us a destination register with some writemask set.  We create the 
> "math" instruction using dst, so it inherits that writemask.  This block 
> executes when dst.writemask != WRITEMASK_XYZW.
>
> The point is to override it back to XYZW, since it isn't.

Are you sure?  You are assigning a newly created dst_reg() to math->dst,
so it should have the default writemask for a vec4, which is XYZW
already.  With that fixed and the change you mention above this patch
is:
Reviewed-by: Francisco Jerez <currojerez at riseup.net>

I had a very similar change in my tree, but you beat me to it ;).

>
>> > +      emit(MOV(dst, src_reg(math->dst)));
>> > +   } else if (brw->gen < 6) {
>> > +      math->base_mrf = 1;
>> > +      math->mlen = src1.file == BAD_FILE ? 1 : 2;
>> >     }
>> >  }
>> 
>> Series is
>> 
>> Reviewed-by: Matt Turner <mattst88 at gmail.com>
>
> Thanks!
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