On 04/11/2012 06:33 PM, Eric Anholt wrote:
Cuts 8/1068 instructions from glyphy's fragment shaders on i965.
---
src/glsl/opt_if_simplification.cpp | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/src/glsl/opt_if_simplification.cpp
b/src/glsl/opt_if_simplification.cpp
index 940dd08..7e88208 100644
--- a/src/glsl/opt_if_simplification.cpp
+++ b/src/glsl/opt_if_simplification.cpp
@@ -66,6 +66,14 @@ do_if_simplification(exec_list *instructions)
ir_visitor_status
ir_if_simplification_visitor::visit_leave(ir_if *ir)
{
+ /* If the if statement has nothing on either side, remove it. */
+ if (ir->then_instructions.is_empty()&&
+ ir->else_instructions.is_empty()) {
+ ir->remove();
+ this->made_progress = true;
+ return visit_continue;
+ }
+
/* FINISHME: Ideally there would be a way to note that the condition
results
* FINISHME: in a constant before processing both of the other subtrees.
* FINISHME: This can probably be done with some flags, but it would take
Hah :) Such an obviously good idea.
Reviewed-by: Kenneth Graunke <kenn...@whitecape.org>
I was about to say "but wait, side effects in the condition!" but
quickly remembered: we can't represent those anymore. It's nice not to
have to worry about that. :)
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