[Mesa-dev] [PATCH v2 19/28] glsl: Support double inouts

[Ian Romanick]

On 02/06/2015 06:56 AM, Ilia Mirkin wrote:
> From: Dave Airlie <airlied at gmail.com>
> 
> Signed-off-by: Dave Airlie <airlied at redhat.com>
> ---
>  src/glsl/ir_set_program_inouts.cpp | 28 +++++++++++++++++++++++++---
>  1 file changed, 25 insertions(+), 3 deletions(-)
> 
> diff --git a/src/glsl/ir_set_program_inouts.cpp b/src/glsl/ir_set_program_inouts.cpp
> index 97ead75..b38742c 100644
> --- a/src/glsl/ir_set_program_inouts.cpp
> +++ b/src/glsl/ir_set_program_inouts.cpp
> @@ -81,6 +81,16 @@ is_shader_inout(ir_variable *var)
>            var->data.mode == ir_var_system_value;
>  }
>  
> +static inline bool
> +is_dvec34_inout(ir_variable *var)
> +{
> +   const glsl_type *type = var->type->without_array();
> +   if (type == glsl_type::dvec4_type || type == glsl_type::dvec3_type)
> +      return true;
> +
> +   return false;

Why not just

   const glsl_type *const type = var->type->without_array();
   return type == glsl_type::dvec4_type || type == glsl_type::dvec3_type;

It may also be better to name this something different.  We'll do the
same "doubling" if / when we add support for GL_AMD_gpu_shader_int64.

> +}
> +
>  static void
>  mark(struct gl_program *prog, ir_variable *var, int offset, int len,
>       bool is_fragment_shader)
> @@ -94,19 +104,31 @@ mark(struct gl_program *prog, ir_variable *var, int offset, int len,
>      */
>  
>     for (int i = 0; i < len; i++) {
> +      /* XXX Should it be i * 2 for dvec3/4? */
> +      int idx = var->data.location + var->data.index + offset + i;

I believe it should be i * 2.  Otherwise elements 0 and 1 of a dvec4
array will partially overlap.  That seems... bad.

>        GLbitfield64 bitfield =
> -         BITFIELD64_BIT(var->data.location + var->data.index + offset + i);
> +         BITFIELD64_BIT(idx);
> +
> +      /* dvec3 and dvec4 take up 2 slots */
> +      if (is_dvec34_inout(var))
> +         bitfield |= bitfield << 1;
>        if (var->data.mode == ir_var_shader_in) {
>  	 prog->InputsRead |= bitfield;
>           if (is_fragment_shader) {
>              gl_fragment_program *fprog = (gl_fragment_program *) prog;
> -            fprog->InterpQualifier[var->data.location +
> -                                   var->data.index + offset + i] =
> +            fprog->InterpQualifier[idx] =
>                 (glsl_interp_qualifier) var->data.interpolation;
>              if (var->data.centroid)
>                 fprog->IsCentroid |= bitfield;
>              if (var->data.sample)
>                 fprog->IsSample |= bitfield;
> +
> +            /* Set the InterpQualifier of the next slot to the same as the
> +             * current one, since dvec3 and dvec4 spans 2 slots.
> +             */
> +            if (is_dvec34_inout(var))
> +               fprog->InterpQualifier[idx + 1] =
> +                  (glsl_interp_qualifier) var->data.interpolation;
>           }
>        } else if (var->data.mode == ir_var_system_value) {
>           prog->SystemValuesRead |= bitfield;
>