Revision: 18090
Author: [email protected]
Date: Wed Nov 27 07:13:00 2013 UTC
Log: Avoid copying flow-sensitive state when only a goto separates
blocks.
BUG=
[email protected]
Review URL: https://codereview.chromium.org/48353007
http://code.google.com/p/v8/source/detail?r=18090
Modified:
/branches/bleeding_edge/src/hydrogen-flow-engine.h
=======================================
--- /branches/bleeding_edge/src/hydrogen-flow-engine.h Mon Oct 14 09:22:19
2013 UTC
+++ /branches/bleeding_edge/src/hydrogen-flow-engine.h Wed Nov 27 07:13:00
2013 UTC
@@ -138,12 +138,19 @@
}
// Propagate the block state forward to all successor blocks.
- for (int i = 0; i < block->end()->SuccessorCount(); i++) {
+ int max = block->end()->SuccessorCount();
+ for (int i = 0; i < max; i++) {
HBasicBlock* succ = block->end()->SuccessorAt(i);
IncrementPredecessorCount(succ);
if (StateAt(succ) == NULL) {
// This is the first state to reach the successor.
- SetStateAt(succ, state->Copy(succ, zone_));
+ if (max == 1 && succ->predecessors()->length() == 1) {
+ // Optimization: successor can inherit this state.
+ SetStateAt(succ, state);
+ } else {
+ // Successor needs a copy of the state.
+ SetStateAt(succ, state->Copy(succ, zone_));
+ }
} else {
// Merge the current state with the state already at the
successor.
SetStateAt(succ, state->Merge(succ, StateAt(succ), zone_));
--
--
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