[Mesa-dev] [PATCH] glsl: Make read_from_write_only_variable_visitor ignore .length().

[Kenneth Graunke]

.length() on an unsized SSBO variable doesn't actually read any data
from the SSBO, and is allowed on variables marked 'writeonly'.

Fixes compute shader compilation in Shadow of Mordor.

Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/glsl/ast_to_hir.cpp | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/glsl/ast_to_hir.cpp b/src/glsl/ast_to_hir.cpp
index f3966d7..13696a3 100644
--- a/src/glsl/ast_to_hir.cpp
+++ b/src/glsl/ast_to_hir.cpp
@@ -106,6 +106,15 @@ public:
       return found;
    }
 
+   virtual ir_visitor_status visit_enter(ir_expression *ir)
+   {
+      /* .length() doesn't actually read anything */
+      if (ir->operation == ir_unop_ssbo_unsized_array_length)
+         return visit_continue_with_parent;
+
+      return visit_continue;
+   }
+
 private:
    ir_variable *found;
 };
-- 
2.7.0