Reviewers: Michael Starzinger,
Description:
Make DeltaBlue performance more stable by ignoring type feedback that
tells us that a map can transition to another map when we are generating
code for load operations. This may cause us to deopt if the same routine
is seeing different maps caused by branching in constructors. If so, I
have a different change that is around 100 times more complicated that
lets us generated Crankshaft code for negative lookups.
Please review this at https://chromiumcodereview.appspot.com/10306010/
SVN Base: http://v8.googlecode.com/svn/branches/bleeding_edge/
Affected files:
M src/hydrogen-instructions.cc
Index: src/hydrogen-instructions.cc
===================================================================
--- src/hydrogen-instructions.cc (revision 11473)
+++ src/hydrogen-instructions.cc (working copy)
@@ -1603,6 +1603,7 @@
SetOperandAt(1, object);
set_representation(Representation::Tagged());
SetGVNFlag(kDependsOnMaps);
+ int map_transitions = 0;
for (int i = 0;
i < types->length() && types_.length() < kMaxLoadPolymorphism;
++i) {
@@ -1624,13 +1625,19 @@
case CONSTANT_FUNCTION:
types_.Add(types->at(i));
break;
+ case MAP_TRANSITION:
+ // We should just ignore these since they are not relevant to a
load
+ // operation.
+ map_transitions++;
+ break;
default:
break;
}
}
}
- if (types_.length() == types->length() &&
FLAG_deoptimize_uncommon_cases) {
+ if (types_.length() + map_transitions == types->length() &&
+ FLAG_deoptimize_uncommon_cases) {
SetFlag(kUseGVN);
} else {
SetAllSideEffects();
--
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