Added support for specialization constants. They are now automaticall…

[NikichaTV]

As commit name states, I added support for specialization constants. All the code written follows the already-established style of the SPIRV-Reflect codebase, and I have provided all the needed functions/fields, that such a feature would make sense to have.

Additions:

1. Two new fields within SpvReflectShaderModule:

   • uint32_t specialization_constant_count;
   • SpvReflectSpecializationConstant* specialization_constants;

   As you can see, a new type SpvReflectSpecializationConstant has also been added. It includes the following members:

   • const char* name;
   • uint32_t spirv_id;
   • uint32_t constant_id;
   • uint32_t size;
   • SpvReflectSpecializationConstantType constant_type; where all possible types are:
     • SPV_REFLECT_SPECIALIZATION_CONSTANT_BOOL
     • SPV_REFLECT_SPECIALIZATION_CONSTANT_INT
     • SPV_REFLECT_SPECIALIZATION_CONSTANT_FLOAT
   • union { float float_value; uint32_t uint_bool_value } default_value;

   These fields can freely be accessed in SpvReflectShaderModule, just as all other types (push_constant_blocks, descriptor_bindings, etc.) are.

2. Two new enumerating methods:

   • spvReflectEnumerateSpecializationConstants(p_module, p_count, pp_constants) - a static method in spirv-reflect.h, which works like any other spvReflectEnumerate... method.

   • ShaderModule::EnumerateSpecializationConstants(p_count, pp_constants) - a public member method of the ShaderModule class. Just like the rest of ShaderModule's member enumerating functions, it relies on its static counterpart in spirv-reflect.h under the hood (in this case - spvReflectEnumerateSpecializationConstants()).

3. Last but not least, SpvReflectToYaml (aka the yamlizer) also picks up specialization constants and displays them same way all other members are shown. Example:

specialization_constant_count: 3, 
specialization_constants:
    - *sc0 # "ENABLE_SHADOWS"
      spirv_id: 443
      constant_id: 0
      size: 4
      default_value (as float): 1.4013e-45
      default_value (as int): 1
      ...

4. There are a few other new internal functions (for example for parsing the specialization constants), but they, obviously, will not be available to the user.

Note that all the new additions are properly documented, once again, following the general styling of SPIRV-Reflect's documentation within the code.

[CLAassistant]

All committers have signed the CLA.

[NikichaTV]

In the second commit, I made push constant fields' names to be their actual GLSL in-shader member names (not their type names, which what they were populated with before). See this link.

[shangjiaxuan]

Hello, I don't want to intrude, but what's the main difference of this pr from mine #154 aside from having yaml output but no 64 bit and evaluation?

[NikichaTV]

Hello, @shangjiaxuan, it seems I have glossed over your PR, as I had not seen it before. I wish I had - this would have made my life much simpler! Anyway, I see they are very similar now, so if you want to, I could close this PR. You can by the way take the YAML output bit and put it in yours, as it is the original one.

[shangjiaxuan]

@NikichaTV I'm sorry I didn't have a good description in the pr until yesterday. I didn't implement YAML because I'm not quite familiar with YAML, and because the tests currently tests YAML by string comparison against set result (Adding will fail tests. I also added a few to test my added features, and failing early on will mean it may not test my cases). I hope you can leave this open so that when maintainers decide to merge or integrate this feature, they can be merged together.