[Mesa-dev] [PATCH 13/37] glsl: add xfb_stride compile time rules

[Timothy Arceri]

>From the ARB_enhanced_layouts spec:

   "The *xfb_stride* qualifier specifies how many bytes are consumed
   by each captured vertex.  It applies to the transform feedback
   buffer for that declaration, whether it is inherited or explicitly
   declared. It can be applied to variables, blocks, block members,
   or just the qualifier out.  If the buffer is capturing any
   double-typed outputs, the stride must be a multiple of 8, otherwise
   it must be a multiple of 4, or a compile-time or link-time error
   results.

   ...

   The resulting stride (implicit or explicit) must be less than or
   equal to the implementation-dependent constant
   gl_MaxTransformFeedbackInterleavedComponents."
---
 src/compiler/glsl/ast_to_hir.cpp | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/src/compiler/glsl/ast_to_hir.cpp b/src/compiler/glsl/ast_to_hir.cpp
index 8a13369..aa94b8a 100644
--- a/src/compiler/glsl/ast_to_hir.cpp
+++ b/src/compiler/glsl/ast_to_hir.cpp
@@ -3225,6 +3225,15 @@ apply_layout_qualifier_to_variable(const struct ast_type_qualifier *qual,
       }
    }
 
+   if (qual->flags.q.explicit_xfb_stride) {
+      unsigned qual_xfb_stride;
+      if (process_qualifier_constant(state, loc, "xfb_stride",
+                                     qual->xfb_stride, &qual_xfb_stride)) {
+         var->data.xfb_stride = qual_xfb_stride;
+         var->data.explicit_xfb_stride = true;
+      }
+   }
+
    if (var->type->contains_atomic()) {
       if (var->data.mode == ir_var_uniform) {
          if (var->data.explicit_binding) {
@@ -6509,6 +6518,15 @@ ast_process_struct_or_iface_block_members(exec_list *instructions,
          xfb_buffer = (int) block_xfb_buffer;
       }
 
+      int xfb_stride = -1;
+      if (qual->flags.q.explicit_xfb_stride) {
+         unsigned qual_xfb_stride;
+         if (process_qualifier_constant(state, &loc, "xfb_stride",
+                                        qual->xfb_stride, &qual_xfb_stride)) {
+            xfb_stride = (int) qual_xfb_stride;
+         }
+      }
+
       if (qual->flags.q.uniform && qual->has_interpolation()) {
          _mesa_glsl_error(&loc, state,
                           "interpolation qualifiers cannot be used "
@@ -6557,6 +6575,7 @@ ast_process_struct_or_iface_block_members(exec_list *instructions,
          fields[i].offset = -1;
          fields[i].explicit_xfb_buffer = explicit_xfb_buffer;
          fields[i].xfb_buffer = xfb_buffer;
+         fields[i].xfb_stride = xfb_stride;
 
          if (qual->flags.q.explicit_location) {
             unsigned qual_location;
@@ -6952,6 +6971,14 @@ ast_interface_block::hir(exec_list *instructions,
       }
    }
 
+   unsigned qual_xfb_stride;
+   if (layout.flags.q.explicit_xfb_stride) {
+      if (!process_qualifier_constant(state, &loc, "xfb_stride",
+                                      layout.xfb_stride, &qual_xfb_stride)) {
+         return NULL;
+      }
+   }
+
    unsigned expl_location = 0;
    if (layout.flags.q.explicit_location) {
       if (!process_qualifier_constant(state, &loc, "location",
-- 
2.5.0