glsl: add xfb helpers and fields to the tfeedback_decl class

We also apply any array/struct offsets.

Reviewed-by: Dave Airlie <airlied@redhat.com>

src/compiler/glsl/link_varyings.cpp

@@ -506,6 +506,8 @@ tfeedback_decl::init(struct gl_context *ctx, const void *mem_ctx,
    this->next_buffer_separator = false;
    this->matched_candidate = NULL;
    this->stream_id = 0;
+   this->buffer = 0;
+   this->offset = 0;
 
    if (ctx->Extensions.ARB_transform_feedback3) {
       /* Parse gl_NextBuffer. */
@@ -598,6 +600,8 @@ tfeedback_decl::assign_location(struct gl_context *ctx,
       = this->matched_candidate->toplevel_var->data.location * 4
       + this->matched_candidate->toplevel_var->data.location_frac
       + this->matched_candidate->offset;
+   const unsigned dmul =
+      this->matched_candidate->type->without_array()->is_double() ? 2 : 1;
 
    if (this->matched_candidate->type->is_array()) {
       /* Array variable */
@@ -605,8 +609,6 @@ tfeedback_decl::assign_location(struct gl_context *ctx,
          this->matched_candidate->type->fields.array->matrix_columns;
       const unsigned vector_elements =
          this->matched_candidate->type->fields.array->vector_elements;
-      const unsigned dmul =
-         this->matched_candidate->type->fields.array->is_double() ? 2 : 1;
       unsigned actual_array_size;
       switch (this->lowered_builtin_array_variable) {
       case clip_distance:
@@ -684,6 +686,12 @@ tfeedback_decl::assign_location(struct gl_context *ctx,
     */
    this->stream_id = this->matched_candidate->toplevel_var->data.stream;
 
+   unsigned array_offset = this->array_subscript * 4 * dmul;
+   unsigned struct_offset = this->matched_candidate->offset * 4 * dmul;
+   this->buffer = this->matched_candidate->toplevel_var->data.xfb_buffer;
+   this->offset = this->matched_candidate->toplevel_var->data.offset +
+      array_offset + struct_offset;
+
    return true;
 }
 

src/compiler/glsl/link_varyings.h

@@ -122,6 +122,16 @@ public:
       return this->stream_id;
    }
 
+   unsigned get_buffer() const
+   {
+      return this->buffer;
+   }
+
+   unsigned get_offset() const
+   {
+      return this->offset;
+   }
+
    /**
     * The total number of varying components taken up by this variable.  Only
     * valid if assign_location() has been called.
@@ -201,6 +211,16 @@ private:
     */
    int location;
 
+   /**
+    * Used to store the buffer assigned by xfb_buffer.
+    */
+   unsigned buffer;
+
+   /**
+    * Used to store the offset assigned by xfb_offset.
+    */
+   unsigned offset;
+
    /**
     * If non-zero, then this variable may be packed along with other variables
     * into a single varying slot, so this offset should be applied when