[Mesa-dev] [PATCH 1/2] nir: optimize min(min(a, b), c) to min3(a, b, c) under an option

[Ian Romanick]

On 06/01/2018 10:17 AM, Eric Anholt wrote:
> Samuel Pitoiset <samuel.pitoiset at gmail.com> writes:
> 
>> On 06/01/2018 02:17 AM, Ian Romanick wrote:
>>> On 05/30/2018 10:06 AM, Samuel Pitoiset wrote:
>>>> Similar for max().
>>>>
>>>> Signed-off-by: Samuel Pitoiset <samuel.pitoiset at gmail.com>
>>>> ---
>>>>   src/compiler/nir/nir.h                | 3 +++
>>>>   src/compiler/nir/nir_opt_algebraic.py | 8 ++++++++
>>>>   2 files changed, 11 insertions(+)
>>>>
>>>> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
>>>> index f6086bd6c0..04991b7d04 100644
>>>> --- a/src/compiler/nir/nir.h
>>>> +++ b/src/compiler/nir/nir.h
>>>> @@ -1897,6 +1897,9 @@ typedef struct nir_shader_compiler_options {
>>>>      /* lower b2f to iand */
>>>>      bool lower_b2f;
>>>>   
>>>> +   /* lower min(min(a, b), c) to min3(a, b, c) (same for max()). */
>>>> +   bool lower_minmax3;
>>>
>>> The way this variable is named and the way it is used is confusing.
>>> Every other lower_foo means "convert foo to something else."  This one
>>> means "make some foo."
>>
>> Yes, the name is not that good. Any suggestions?
> 
> We use !options->lower_fsat to decide if we should turn min(max())
> patterns into fsat, so we could go with that model again.  You'd just
> need to be sure to update other NIR drivers to flag lower_minmax3 so
> they don't start seeing unexpected minmax3s.

Sounds good to me.

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