[Mesa-dev] [PATCH] nir: Always print non-xyzw swizzles.

[Ilia Mirkin]

On Tue, Sep 22, 2015 at 12:45 AM, Matt Turner <mattst88 at gmail.com> wrote:
> On Mon, Sep 21, 2015 at 9:37 PM, Ilia Mirkin <imirkin at alum.mit.edu> wrote:
>> On Tue, Sep 22, 2015 at 12:31 AM, Matt Turner <mattst88 at gmail.com> wrote:
>>> Previously we would not print a swizzle on ssa_52 when only its .x
>>> component is used (as seen in the definition of ssa_53):
>>>
>>>    vec3 ssa_52 = fadd ssa_51, ssa_51
>>>    vec1 ssa_53 = flog2 ssa_52
>>>    vec1 ssa_54 = flog2 ssa_52.y
>>>    vec1 ssa_55 = flog2 ssa_52.z
>>>
>>> But this makes the interpretation of the RHS of the definition difficult
>>> to understand and dependent on the size of the LHS. Just print swizzles
>>> when they are not .xyzw (which is only possible on vec4 uses), so the
>>> previous example is now printed as:
>>>
>>>    vec3 ssa_52 = fadd ssa_51.xyz, ssa_51.xyz
>>
>> IMHO if ssa_51 is a vec3, this makes sense without the .xyz. I'd
>> change the condition to print the identity swizzle only if source size
>> != output size, not sure if that's easy to do though.
>
> I actually like it better as is for the same reason as stated -- you
> don't have to know the type of the ssa value to know what it is.

Well, you'd know based on whether the swizzle is printed or not. If no
swizzle, then it's the same size as the dest. Anyways, your way is an
argument to always just print the swizzle, for vec4's as well.

  -ilia