[Mesa-stable] [PATCH] glsl: change ast_type_qualifier bitset size to work around GCC 5.4 bug

[Brian Paul]

Change the size of the bitset from 128 bits to 96.  This works around an
apparent GCC 5.4 bug in which bad SSE code is generated, leading to a
crash in ast_type_qualifier::validate_in_qualifier() (ast_type.cpp:654).

This can be repro'd with the Piglit test tests/spec/glsl-1.50/execution/
varying-struct-basic-gs-fs.shader_test

Bugzilla:https://bugs.freedesktop.org/show_bug.cgi?id=105497
Cc: mesa-stable at lists.freedesktop.org
---
 src/compiler/glsl/ast.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/compiler/glsl/ast.h b/src/compiler/glsl/ast.h
index a1ec0d5..9b88ff5 100644
--- a/src/compiler/glsl/ast.h
+++ b/src/compiler/glsl/ast.h
@@ -474,7 +474,13 @@ enum {
 
 struct ast_type_qualifier {
    DECLARE_RALLOC_CXX_OPERATORS(ast_type_qualifier);
-   DECLARE_BITSET_T(bitset_t, 128);
+   /* Note: this bitset needs to have at least as many bits as the 'q'
+    * struct has flags, below.  Previously, the size was 128 instead of 96.
+    * But an apparent bug in GCC 5.4.0 causes bad SSE code generation
+    * elsewhere, leading to a crash.  96 bits works around the issue.
+    * See https://bugs.freedesktop.org/show_bug.cgi?id=105497
+    */
+   DECLARE_BITSET_T(bitset_t, 96);
 
    union flags {
       struct {
-- 
2.7.4