nir: Add members for the explicit XFB properties to nir_variable

These are copied from the from the corresponding values in
ir_variable. The intention is to eventually use them in a pure-NIR
linker.

Reviewed-by: Timothy Arceri <tarceri@itsqueeze.com>

src/compiler/glsl/glsl_to_nir.cpp

@@ -440,6 +440,10 @@ nir_visitor::visit(ir_variable *ir)
    var->data.image.restrict_flag = ir->data.memory_restrict;
    var->data.image.format = ir->data.image_format;
    var->data.fb_fetch_output = ir->data.fb_fetch_output;
+   var->data.explicit_xfb_buffer = ir->data.explicit_xfb_buffer;
+   var->data.explicit_xfb_stride = ir->data.explicit_xfb_stride;
+   var->data.xfb_buffer = ir->data.xfb_buffer;
+   var->data.xfb_stride = ir->data.xfb_stride;
 
    var->num_state_slots = ir->get_num_state_slots();
    if (var->num_state_slots > 0) {

src/compiler/nir/nir.h

@@ -259,6 +259,21 @@ typedef struct nir_variable {
        */
       unsigned explicit_binding:1;
 
+      /**
+       * Was a transfer feedback buffer set in the shader?
+       */
+      unsigned explicit_xfb_buffer:1;
+
+      /**
+       * Was a transfer feedback stride set in the shader?
+       */
+      unsigned explicit_xfb_stride:1;
+
+      /**
+       * Was an explicit offset set in the shader?
+       */
+      unsigned explicit_offset:1;
+
       /**
        * \brief Layout qualifier for gl_FragDepth.
        *
@@ -320,10 +335,20 @@ typedef struct nir_variable {
       int binding;
 
       /**
-       * Location an atomic counter is stored at.
+       * Location an atomic counter or transform feedback is stored at.
        */
       unsigned offset;
 
+      /**
+       * Transform feedback buffer.
+       */
+      unsigned xfb_buffer;
+
+      /**
+       * Transform feedback stride.
+       */
+      unsigned xfb_stride;
+
       /**
        * ARB_shader_image_load_store qualifiers.
        */