Mesa (master): glsl: Add a quick hack to constant folding to reduce duplicated work.
Eric Anholt
anholt at kemper.freedesktop.org
Thu Aug 26 17:53:36 UTC 2010
Module: Mesa
Branch: master
Commit: 2db7bb9c665d13fd067109b1171eedd92764791d
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=2db7bb9c665d13fd067109b1171eedd92764791d
Author: Eric Anholt <eric at anholt.net>
Date: Thu Aug 26 10:42:47 2010 -0700
glsl: Add a quick hack to constant folding to reduce duplicated work.
Reduces runtime of glsl-max-varyings 92% on my system.
---
src/glsl/ir_constant_folding.cpp | 13 +++++++++++++
1 files changed, 13 insertions(+), 0 deletions(-)
diff --git a/src/glsl/ir_constant_folding.cpp b/src/glsl/ir_constant_folding.cpp
index 3e6934c..554c54f 100644
--- a/src/glsl/ir_constant_folding.cpp
+++ b/src/glsl/ir_constant_folding.cpp
@@ -62,6 +62,19 @@ ir_constant_folding_visitor::handle_rvalue(ir_rvalue **rvalue)
if (*rvalue == NULL || (*rvalue)->ir_type == ir_type_constant)
return;
+ /* Note that we do rvalue visitoring on leaving. So if an
+ * expression has a non-constant operand, no need to go looking
+ * down it to find if it's constant. This cuts the time of this
+ * pass down drastically.
+ */
+ ir_expression *expr = (*rvalue)->as_expression();
+ if (expr) {
+ for (unsigned int i = 0; i < expr->get_num_operands(); i++) {
+ if (!expr->operands[i]->as_constant())
+ return;
+ }
+ }
+
ir_constant *constant = (*rvalue)->constant_expression_value();
if (constant) {
*rvalue = constant;
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