[Mesa-dev] [PATCH 6/8] glsl: check total count of multi-slot double vertex attribs

[Dave Airlie]

From: Dave Airlie <airlied at redhat.com>

The spec is vague all over the place about this, but this seems
to be the intent, we can probably make this optional later if
someone makes hw that cares and writes a driver.

Basically we need to double count some of the d types but
only for totalling not for slot number assignment.

Signed-off-by: Dave Airlie <airlied at redhat.com>
---
 src/glsl/linker.cpp | 40 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 39 insertions(+), 1 deletion(-)

diff --git a/src/glsl/linker.cpp b/src/glsl/linker.cpp
index 21fde94..5803f82 100644
--- a/src/glsl/linker.cpp
+++ b/src/glsl/linker.cpp
@@ -1975,6 +1975,7 @@ assign_attribute_or_color_locations(gl_shader_program *prog,
    } to_assign[16];
 
    unsigned num_attr = 0;
+   unsigned total_attribs_size = 0;
 
    foreach_in_list(ir_instruction, node, sh->ir) {
       ir_variable *const var = node->as_variable();
@@ -2016,12 +2017,41 @@ assign_attribute_or_color_locations(gl_shader_program *prog,
 	 }
       }
 
+      const unsigned slots = var->type->count_attribute_slots();
+
+      /* From GL4.5 core spec, section 11.1.1 (Vertex Attributes):
+       *
+       * "A program with more than the value of MAX_VERTEX_ATTRIBS active
+       * attribute variables may fail to link, unless device-dependent
+       * optimizations are able to make the program fit within available
+       * hardware resources. For the purposes of this test, attribute variables
+       * of the type dvec3, dvec4, dmat2x3, dmat2x4, dmat3, dmat3x4, dmat4x3,
+       * and dmat4 may count as consuming twice as many attributes as equivalent
+       * single-precision types. While these types use the same number of
+       * generic attributes as their single-precision equivalents,
+       * implementations are permitted to consume two single-precision vectors
+       * of internal storage for each three- or four-component double-precision
+       * vector."
+       * Until someone has a good reason in Mesa, enforce that now.
+       */
+      if (target_index == MESA_SHADER_VERTEX) {
+	 total_attribs_size += slots;
+	 if (var->type->without_array() == glsl_type::dvec3_type ||
+	     var->type->without_array() == glsl_type::dvec4_type ||
+	     var->type->without_array() == glsl_type::dmat2x3_type ||
+	     var->type->without_array() == glsl_type::dmat2x4_type ||
+	     var->type->without_array() == glsl_type::dmat3_type ||
+	     var->type->without_array() == glsl_type::dmat3x4_type ||
+	     var->type->without_array() == glsl_type::dmat4x3_type ||
+	     var->type->without_array() == glsl_type::dmat4_type)
+	    total_attribs_size += slots;
+      }
+
       /* If the variable is not a built-in and has a location statically
        * assigned in the shader (presumably via a layout qualifier), make sure
        * that it doesn't collide with other assigned locations.  Otherwise,
        * add it to the list of variables that need linker-assigned locations.
        */
-      const unsigned slots = var->type->count_attribute_slots();
       if (var->data.location != -1) {
 	 if (var->data.location >= generic_base && var->data.index < 1) {
 	    /* From page 61 of the OpenGL 4.0 spec:
@@ -2141,6 +2171,14 @@ assign_attribute_or_color_locations(gl_shader_program *prog,
       num_attr++;
    }
 
+   if (target_index == MESA_SHADER_VERTEX) {
+      if (total_attribs_size > max_index) {
+	 linker_error(prog,
+		      "attempt to use %d vertex attribute slots only %d available ",
+		      total_attribs_size, max_index);
+	 return false;
+      }
+   }
    /* If all of the attributes were assigned locations by the application (or
     * are built-in attributes with fixed locations), return early.  This should
     * be the common case.
-- 
2.1.0