Mesa (master): glsl: Do not vectorize vector array dereferences.

[Matt Turner]

Module: Mesa
Branch: master
Commit: 025d99ce3cea21c9ecea77b95655c0c838b2fa3c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=025d99ce3cea21c9ecea77b95655c0c838b2fa3c

Author: Matt Turner <mattst88 at gmail.com>
Date:   Mon Feb 10 12:09:19 2014 -0800

glsl: Do not vectorize vector array dereferences.

Array dereferences must have scalar indices, so we cannot vectorize
them.

Cc: "10.1" <mesa-stable at lists.freedesktop.org>
Reported-by: Andrew Guertin <lists at dolphinling.net>
Tested-by: Andrew Guertin <lists at dolphinling.net>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>

---

 src/glsl/opt_vectorize.cpp |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/src/glsl/opt_vectorize.cpp b/src/glsl/opt_vectorize.cpp
index 8ee81f1..dba303d 100644
--- a/src/glsl/opt_vectorize.cpp
+++ b/src/glsl/opt_vectorize.cpp
@@ -82,6 +82,7 @@ public:
 
    virtual ir_visitor_status visit_enter(ir_assignment *);
    virtual ir_visitor_status visit_enter(ir_swizzle *);
+   virtual ir_visitor_status visit_enter(ir_dereference_array *);
    virtual ir_visitor_status visit_enter(ir_if *);
    virtual ir_visitor_status visit_enter(ir_loop *);
 
@@ -289,6 +290,19 @@ ir_vectorize_visitor::visit_enter(ir_swizzle *ir)
    return visit_continue;
 }
 
+/* Upon entering an ir_array_dereference, remove the current assignment from
+ * further consideration. Since the index of an array dereference must scalar,
+ * we are not able to vectorize it.
+ *
+ * FINISHME: If all of scalar indices are identical we could vectorize.
+ */
+ir_visitor_status
+ir_vectorize_visitor::visit_enter(ir_dereference_array *ir)
+{
+   this->current_assignment = NULL;
+   return visit_continue_with_parent;
+}
+
 /* Since there is no statement to visit between the "then" and "else"
  * instructions try to vectorize before, in between, and after them to avoid
  * combining statements from different basic blocks.