[Mesa-dev] [PATCH 1/2] glsl: Fix incorrect pattern matching in ir_set_program_inouts

[Paul Berry]

In commit 8fc41df (glsl: Modify ir_set_program_inouts to handle
geometry shaders), when attempting to pattern match the "foo" part of
expressions such as:

   foo[i][j]
   foo[i]

I incorrectly called as_dereference_variable() on the subexpression
foo[i] instead of foo.  As a result, the pattern never matched, so
ir_set_program_inouts would fall back on marking the entire variable
as used, rather than just the portion indexed by the array.

This didn't result in incorrect behaviour, but it could have resulted
in inefficiency by causing the back-end to allocate resources for
unused parts of an input or output array.
---
 src/glsl/ir_set_program_inouts.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/glsl/ir_set_program_inouts.cpp b/src/glsl/ir_set_program_inouts.cpp
index c6abc82..6196d6a 100644
--- a/src/glsl/ir_set_program_inouts.cpp
+++ b/src/glsl/ir_set_program_inouts.cpp
@@ -235,7 +235,7 @@ ir_set_program_inouts_visitor::visit_enter(ir_dereference_array *ir)
        * inner_array => foo[i]
        */
       if (ir_dereference_variable * const deref_var =
-          inner_array->as_dereference_variable()) {
+          inner_array->array->as_dereference_variable()) {
          if (this->shader_type == GL_GEOMETRY_SHADER &&
              deref_var->var->mode == ir_var_shader_in) {
             /* foo is a geometry shader input, so i is the vertex, and j the
@@ -253,7 +253,7 @@ ir_set_program_inouts_visitor::visit_enter(ir_dereference_array *ir)
          }
       }
    } else if (ir_dereference_variable * const deref_var =
-              ir->as_dereference_variable()) {
+              ir->array->as_dereference_variable()) {
       /* ir => foo[i], where foo is a variable. */
       if (this->shader_type == GL_GEOMETRY_SHADER &&
           deref_var->var->mode == ir_var_shader_in) {
-- 
1.8.3.4