---
Easiest thing for now seems to be to bail if we see these
kinds of dereferences. I'll squash this in, adding a description
of the things we don't handle.
src/glsl/opt_rebalance_tree.cpp | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/src/glsl/opt_rebalance_tree.cpp b/src/glsl/opt_rebalance_tree.cpp
index 5866a60..773aab3 100644
--- a/src/glsl/opt_rebalance_tree.cpp
+++ b/src/glsl/opt_rebalance_tree.cpp
@@ -167,6 +167,19 @@ is_reduction_operation(ir_expression_operation operation)
/* Note that this function does not attempt to recognize that reduction trees
* are already balanced.
+ *
+ * We return false from this function for a number of reasons other than an
+ * expression tree not being a mathematical reduction. Namely,
+ *
+ * - if the tree contains multiple constants that we may be able to combine.
+ * - if the tree contains matrices:
+ * - they might contain vec4's with many constant components that we can
+ * simplify after splitting.
+ * - applying the matrix chain ordering optimization is more than just
+ * balancing an expression tree.
+ * - if the tree contains operations on multiple types.
+ * - if the tree contains ir_dereference_{array,record}, since foo[a+b] + c
+ * would trick the visiting pass.
*/
static void
is_reduction(ir_instruction *ir, void *data)
@@ -186,6 +199,15 @@ is_reduction(ir_instruction *ir, void *data)
return;
}
+ /* Array/record dereferences have subtrees that are not part of the expr
+ * tree we're balancing. Skip trees containing them.
+ */
+ if (ir->ir_type == ir_type_dereference_array ||
+ ir->ir_type == ir_type_dereference_record) {
+ ird->is_reduction = false;
+ return;
+ }
+
ir_expression *expr = ir->as_expression();
if (!expr)
return;
--
1.8.3.2
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