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authorMatt Turner <mattst88@gmail.com>2014-07-15 15:29:29 -0700
committerMatt Turner <mattst88@gmail.com>2014-07-24 11:27:43 -0700
commitac2acf04f750a84fc6381b6efacfe1bbac61aa4d (patch)
treef211083c73cffe44f808a58d12d8d13fb082626c /src/mesa
parent0ddc28b026688df79e54d3af1d7914ff04b12fed (diff)
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i965: Improve dead control flow elimination.
... to eliminate an ELSE instruction followed immediately by an ENDIF. instructions in affected programs: 704 -> 700 (-0.57%) Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
Diffstat (limited to 'src/mesa')
-rw-r--r--src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp25
1 files changed, 15 insertions, 10 deletions
diff --git a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
index 14c6898..f0530a1 100644
--- a/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
+++ b/src/mesa/drivers/dri/i965/brw_dead_control_flow.cpp
@@ -32,6 +32,7 @@
/* Look for and eliminate dead control flow:
*
* - if/endif
+ * . else in else/endif
* - if/else/endif
*/
bool
@@ -54,24 +55,28 @@ dead_control_flow_eliminate(backend_visitor *v)
backend_instruction *if_inst = NULL, *else_inst = NULL;
backend_instruction *prev_inst = (backend_instruction *) endif_inst->prev;
- if (prev_inst->opcode == BRW_OPCODE_IF) {
- if_inst = prev_inst;
- found = true;
- } else if (prev_inst->opcode == BRW_OPCODE_ELSE) {
+ if (prev_inst->opcode == BRW_OPCODE_ELSE) {
else_inst = prev_inst;
+ found = true;
prev_inst = (backend_instruction *) prev_inst->prev;
- if (prev_inst->opcode == BRW_OPCODE_IF) {
- if_inst = prev_inst;
- found = true;
- }
+ }
+
+ if (prev_inst->opcode == BRW_OPCODE_IF) {
+ if_inst = prev_inst;
+ found = true;
+ } else {
+ /* Don't remove the ENDIF if we didn't find a dead IF. */
+ endif_inst = NULL;
}
if (found) {
- if_inst->remove();
+ if (if_inst)
+ if_inst->remove();
if (else_inst)
else_inst->remove();
- endif_inst->remove();
+ if (endif_inst)
+ endif_inst->remove();
progress = true;
}
}