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

[Jose Maria Casanova Crespo]

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);
          }
 
-- 
2.19.1