[Mesa-dev] [PATCH v2 1/3] glsl: add glsl_external_mode() helper

[Marek Olšák]

On Thu, May 17, 2018 at 12:50 AM, Timothy Arceri <tarceri at itsqueeze.com>
wrote:

>
>
> On 17/05/18 14:36, Marek Olšák wrote:
>
>> On Wed, May 16, 2018 at 11:01 PM, Timothy Arceri <tarceri at itsqueeze.com
>> <mailto:tarceri at itsqueeze.com>> wrote:
>>
>>
>>
>>     On 17/05/18 10:59, Marek Olšák wrote:
>>
>>         On Sat, May 12, 2018 at 12:49 AM, Timothy Arceri
>>         <tarceri at itsqueeze.com <mailto:tarceri at itsqueeze.com>
>>         <mailto:tarceri at itsqueeze.com <mailto:tarceri at itsqueeze.com>>>
>>
>>         wrote:
>>
>>              This allows us to get the variable mode as specified by the
>>         GLSL
>>              spec. We will use this in the following patch.
>>              ---
>>                src/compiler/glsl/ast_to_hir.cpp | 73
>>         ++++++++++++++++++++++++++++++++
>>                1 file changed, 73 insertions(+)
>>
>>              diff --git a/src/compiler/glsl/ast_to_hir.cpp
>>              b/src/compiler/glsl/ast_to_hir.cpp
>>              index 3bf581571e2..a7a9ac80769 100644
>>              --- a/src/compiler/glsl/ast_to_hir.cpp
>>              +++ b/src/compiler/glsl/ast_to_hir.cpp
>>              @@ -4175,6 +4175,79 @@
>>         apply_type_qualifier_to_variable(const struct
>>              ast_type_qualifier *qual,
>>                   apply_image_qualifier_to_variable(qual, var, state,
>> loc);
>>                }
>>
>>              +/**
>>              + * Get the GLSL mode specified in for system values (if
>> any).
>>              + */
>>              +static enum ir_variable_mode
>>              +glsl_external_mode(enum ir_variable_mode internal_mode,
>>              gl_shader_stage stage,
>>              +                   unsigned slot) {
>>              +   if (internal_mode == ir_var_system_value) {
>>              +      switch (slot) {
>>              +      case SYSTEM_VALUE_SUBGROUP_SIZE:
>>              +         return ir_var_uniform;
>>              +      case SYSTEM_VALUE_PRIMITIVE_ID:
>>              +         if (stage == MESA_SHADER_GEOMETRY) {
>>              +            return ir_var_shader_out;
>>
>>
>>         System values are always inputs. This one is gl_PrimitiveIDIn.
>>
>>              +         } else {
>>              +            return ir_var_shader_in;
>>              +         }
>>              +      case SYSTEM_VALUE_TESS_LEVEL_OUTER:
>>              +      case SYSTEM_VALUE_TESS_LEVEL_INNER:
>>              +         if (stage == MESA_SHADER_TESS_CTRL) {
>>              +            return ir_var_shader_out;
>>
>>
>>         System values are always inputs, i.e. TESS_CTRL isn't allowed
>> here.
>>
>>
>>     Hmm yeah your right I seem to have confused myself here a bit.
>>     However SYSTEM_VALUE_SUBGROUP_SIZE seems to be the odd one out in
>>     that its a uniform.
>>
>>
>> Why is it uniform?
>>
>
> From ARB_shader_ballot:
>
>
>     (Add to the list of built-in uniform variable declaration)
>
>         uniform uint  gl_SubGroupSizeARB;
>

I think it means that gl_SubGroupSizeARB is a compile-time constant. It
probably shouldn't be a system value.

Marek
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