[Mesa-dev] [PATCH 24/74] glsl: Don't do constant variable on buffer variables

[Iago Toral Quiroga]

Since the backing storage for these is shared we cannot ensure that the
value won't change by writes from other threads.
---
 src/glsl/opt_constant_variable.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/glsl/opt_constant_variable.cpp b/src/glsl/opt_constant_variable.cpp
index 7222eb9..ab78e4c 100644
--- a/src/glsl/opt_constant_variable.cpp
+++ b/src/glsl/opt_constant_variable.cpp
@@ -115,6 +115,13 @@ ir_constant_variable_visitor::visit_enter(ir_assignment *ir)
    if (!var)
       return visit_continue;
 
+   /* Ignore buffer variables, since the underlying storage is shared
+    * and we can't be sure that this variable won't be written by another
+    * thread.
+    */
+   if (var->data.mode == ir_var_buffer)
+      return visit_continue;
+
    constval = ir->rhs->constant_expression_value();
    if (!constval)
       return visit_continue;
-- 
1.9.1