[Mesa-dev] [PATCH 1/3] glsl: XFB TSC per-vertex output varyings match as not declared as arrays

[Chema Casanova]

V2 of this series that address the fix for
KHR-GL*.tessellation_shader.single.xfb_captures_data_from_correct_stage
regressions is available at Gitlab MR!300

https://gitlab.freedesktop.org/mesa/mesa/merge_requests/300

On 21/11/18 19:45, Jose Maria Casanova Crespo wrote:
> Recent change on OpenGL CTS ("Use non-arrayed varying name for TCS blocks")
> on KHR-GL*.tessellation_shader.single.xfb_captures_data_from_correct_stage
> tests changed how to name per-vertex Tessellation Control Shader output
> varyings in transform feedback using interface block as "BLOCK_INOUT.value"
> rather than "BLOCK_INOUT[0].value"
> 
> So Tessellation control shader per-vertex output variables and blocks that
> are required to be declared as arrays, with each element representing output
> values for a single vertex of a multi-vertex primitive are expected to be
> named as they were not declared as arrays.
> 
> This patch adds a new is_xfb_per_vertex_output flag at ir_variable level so
> we mark when an ir_variable is an per-vertex TCS output varying. So we
> treat it in terms on XFB its naming as a non array variable.
> 
> As we don't support NV_gpu_shader5, so PATCHES mode is not accepted as
> primitiveMode parameter of BeginTransformFeedback the test expects a
> failure as we can use the XFB results.
> 
> This patch uncovers that we were passing the GLES version of the tests
> because candidates naming didn't match, not because on GLES the Tessellation
> Control stage varyings shouldn't be XFB candidates in any case. This
> is addressed in the following patch.
> 
> Fixes: KHR-GL4*.tessellation_shader.single.xfb_captures_data_from_correct_stage
> 
> Cc: mesa-stable at lists.freedesktop.org
> ---
>  src/compiler/glsl/ir.cpp            | 1 +
>  src/compiler/glsl/ir.h              | 6 ++++++
>  src/compiler/glsl/link_uniforms.cpp | 6 ++++--
>  src/compiler/glsl/link_varyings.cpp | 8 +++++++-
>  4 files changed, 18 insertions(+), 3 deletions(-)
> 
> diff --git a/src/compiler/glsl/ir.cpp b/src/compiler/glsl/ir.cpp
> index 1d1a56ae9a5..582111d71f5 100644
> --- a/src/compiler/glsl/ir.cpp
> +++ b/src/compiler/glsl/ir.cpp
> @@ -1750,6 +1750,7 @@ ir_variable::ir_variable(const struct glsl_type *type, const char *name,
>     this->data.fb_fetch_output = false;
>     this->data.bindless = false;
>     this->data.bound = false;
> +   this->data.is_xfb_per_vertex_output = false;
>  
>     if (type != NULL) {
>        if (type->is_interface())
> diff --git a/src/compiler/glsl/ir.h b/src/compiler/glsl/ir.h
> index f478b29a6b5..e09f053b77c 100644
> --- a/src/compiler/glsl/ir.h
> +++ b/src/compiler/glsl/ir.h
> @@ -766,6 +766,12 @@ public:
>         */
>        unsigned is_xfb_only:1;
>  
> +      /**
> +       * Is this varying a TSC per-vertex output candidate for transform
> +       * feedback?
> +       */
> +      unsigned is_xfb_per_vertex_output:1;
> +
>        /**
>         * Was a transfor feedback buffer set in the shader?
>         */
> diff --git a/src/compiler/glsl/link_uniforms.cpp b/src/compiler/glsl/link_uniforms.cpp
> index 63e688b19a7..547da68e216 100644
> --- a/src/compiler/glsl/link_uniforms.cpp
> +++ b/src/compiler/glsl/link_uniforms.cpp
> @@ -72,8 +72,10 @@ program_resource_visitor::process(ir_variable *var, bool use_std430_as_default)
>           get_internal_ifc_packing(use_std430_as_default) :
>        var->type->get_internal_ifc_packing(use_std430_as_default);
>  
> -   const glsl_type *t =
> -      var->data.from_named_ifc_block ? var->get_interface_type() : var->type;
> +   const glsl_type *t = var->data.from_named_ifc_block ?
> +      (var->data.is_xfb_per_vertex_output ?
> +       var->get_interface_type()->without_array() :
> +       var->get_interface_type()) : var->type;
>     const glsl_type *t_without_array = t->without_array();
>  
>     /* false is always passed for the row_major parameter to the other
> diff --git a/src/compiler/glsl/link_varyings.cpp b/src/compiler/glsl/link_varyings.cpp
> index 52e493cb599..1964dcc0a22 100644
> --- a/src/compiler/glsl/link_varyings.cpp
> +++ b/src/compiler/glsl/link_varyings.cpp
> @@ -2150,7 +2150,10 @@ private:
>        tfeedback_candidate *candidate
>           = rzalloc(this->mem_ctx, tfeedback_candidate);
>        candidate->toplevel_var = this->toplevel_var;
> -      candidate->type = type;
> +      if (this->toplevel_var->data.is_xfb_per_vertex_output)
> +         candidate->type = type->without_array();
> +      else
> +         candidate->type = type;
>        candidate->offset = this->varying_floats;
>        _mesa_hash_table_insert(this->tfeedback_candidates,
>                                ralloc_strdup(this->mem_ctx, name),
> @@ -2499,6 +2502,9 @@ assign_varying_locations(struct gl_context *ctx,
>  
>           if (num_tfeedback_decls > 0) {
>              tfeedback_candidate_generator g(mem_ctx, tfeedback_candidates);
> +            if (producer->Stage == MESA_SHADER_TESS_CTRL &&
> +                !output_var->data.patch)
> +               output_var->data.is_xfb_per_vertex_output = true;
>              g.process(output_var);
>           }
>  
>