[Mesa-dev] [PATCH 15/20] glsl/es3.1: Allow textureGather and textureGatherOffset in GLSL ES 3.10

[Chris Forbes]

>  /* Only ARB_texture_gather but not GLSL 4.0 or ARB_gpu_shader5.
>   * used for relaxation of const offset requirements.
>   */
>  static bool
> -texture_gather_only(const _mesa_glsl_parse_state *state)
> +texture_gather_only_or_es31(const _mesa_glsl_parse_state *state)
>  {
>     return !state->is_version(400, 0) &&
>            !state->ARB_gpu_shader5_enable &&
> -          state->ARB_texture_gather_enable;
> +          (state->ARB_texture_gather_enable ||
> +           state->is_version(0, 310));
>  }

I don't think this is correct. This is used to enable the restricted
versions of textureGather/textureGatherOffset which require a constant
offset. This restriction doesn't appear to exist in ES3.1 -- it's more
or less the GS5 version.

An example pair, where at most one should be enabled:
    _texture(ir_tg4, texture_gather_only, glsl_type::vec4_type,
glsl_type::sampler2D_type, glsl_type::vec2_type, TEX_OFFSET),
    _texture(ir_tg4, gpu_shader5, glsl_type::vec4_type,
glsl_type::sampler2D_type, glsl_type::vec2_type, TEX_OFFSET_NONCONST),

- Chris