[Mesa-dev] [PATCH 2/2] mesa: check if resource backed by buffer in property queries

[Tapani Pälli]

Patch fixes broken behaviour of queries for following properties, from
ARB_program_interface_query specification:

GL_OFFSET:

   "For active variables not backed by a buffer object, an offset of
   -1 is written to <params>."

GL_ARRAY_STRIDE:

   "For active variables not declared as an array of basic types, zero
   is written to <params>.  For active variables not backed by a buffer
   object, -1 is written to <params>, regardless of the variable type."

GL_MATRIX_STRIDE:

   "For active variables not declared as a matrix or array of matrices,
   zero is written to <params>.  For active variables not backed by a
   buffer object, -1 is written to <params>, regardless of the variable
   type."

These queries may come from GetActiveUniformsiv or GetProgramResourceiv.
Patch implements little helper to do 'backed by buffer' check and returns
appropriate values.

Fixes following CTS test:
   ES31-CTS.shader_atomic_counters.basic-program-query

No Piglit regressions.

Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
---
 src/mesa/main/shader_query.cpp | 40 +++++++++++++++++++++++++++++++++++-----
 1 file changed, 35 insertions(+), 5 deletions(-)

diff --git a/src/mesa/main/shader_query.cpp b/src/mesa/main/shader_query.cpp
index dd51bba..b214691 100644
--- a/src/mesa/main/shader_query.cpp
+++ b/src/mesa/main/shader_query.cpp
@@ -1105,6 +1105,26 @@ invalid_operation:
    return 0;
 }
 
+/**
+ * Helper that returns if given resource is backed by a buffer object,
+ * either UBO, SSBO or atomic counter buffer.
+ */
+static bool
+backed_by_buffer_object(struct gl_program_resource *res)
+{
+   switch (res->Type) {
+   case GL_BUFFER_VARIABLE:
+      return true;
+   case GL_UNIFORM:
+      if (RESOURCE_UNI(res)->block_index != -1 ||
+          RESOURCE_UNI(res)->atomic_buffer_index != -1 ||
+          RESOURCE_UNI(res)->is_shader_storage)
+         return true;
+   default:
+      return false;
+   }
+}
+
 unsigned
 _mesa_program_resource_prop(struct gl_shader_program *shProg,
                             struct gl_program_resource *res, GLuint index,
@@ -1171,20 +1191,30 @@ _mesa_program_resource_prop(struct gl_shader_program *shProg,
       }
    case GL_OFFSET:
       VALIDATE_TYPE_2(GL_UNIFORM, GL_BUFFER_VARIABLE);
-      *val = RESOURCE_UNI(res)->offset;
+      *val = backed_by_buffer_object(res) ? RESOURCE_UNI(res)->offset : -1;
       return 1;
    case GL_BLOCK_INDEX:
       VALIDATE_TYPE_2(GL_UNIFORM, GL_BUFFER_VARIABLE);
       *val = RESOURCE_UNI(res)->block_index;
       return 1;
-   case GL_ARRAY_STRIDE:
+   case GL_ARRAY_STRIDE: {
       VALIDATE_TYPE_2(GL_UNIFORM, GL_BUFFER_VARIABLE);
-      *val = RESOURCE_UNI(res)->array_stride;
+      bool backed = backed_by_buffer_object(res);
+      if (backed && RESOURCE_UNI(res)->array_elements == 0)
+         *val = 0;
+      else
+         *val = backed ? RESOURCE_UNI(res)->array_stride : -1;
       return 1;
-   case GL_MATRIX_STRIDE:
+   }
+   case GL_MATRIX_STRIDE: {
       VALIDATE_TYPE_2(GL_UNIFORM, GL_BUFFER_VARIABLE);
-      *val = RESOURCE_UNI(res)->matrix_stride;
+         bool backed = backed_by_buffer_object(res);
+         if (backed && !RESOURCE_UNI(res)->type->is_matrix())
+            *val = 0;
+         else
+            *val = backed ? RESOURCE_UNI(res)->matrix_stride : -1;
       return 1;
+   }
    case GL_IS_ROW_MAJOR:
       VALIDATE_TYPE_2(GL_UNIFORM, GL_BUFFER_VARIABLE);
       *val = RESOURCE_UNI(res)->row_major;
-- 
2.4.3