Revision: 18255
Author: [email protected]
Date: Wed Dec 4 10:46:18 2013 UTC
Log: Remove unnecessary overflow check in
HGraphBuilder::BuildCreateAllocationMemento().
With this fix codegen looks like:
mov ecx,[eax+0xf] ;;; <@52,#38> load-named-field
add ecx,0x2 ;;; <@54,#40> add-i
mov [eax+0xf],ecx ;;; <@56,#41> store-named-field
without it there is an overflow check and jump to deopt.
x64 code looks similar, except there is an (annoying) smi-untag then
int32-to-smi around the add operation.
[email protected], [email protected]
Review URL: https://codereview.chromium.org/104313003
http://code.google.com/p/v8/source/detail?r=18255
Modified:
/branches/bleeding_edge/src/hydrogen.cc
=======================================
--- /branches/bleeding_edge/src/hydrogen.cc Wed Dec 4 09:27:48 2013 UTC
+++ /branches/bleeding_edge/src/hydrogen.cc Wed Dec 4 10:46:18 2013 UTC
@@ -2592,6 +2592,9 @@
AllocationSite::kMementoCreateCountOffset));
memento_create_count = AddUncasted<HAdd>(
memento_create_count, graph()->GetConstant1());
+ // This smi value is reset to zero after every gc, overflow isn't a
problem
+ // since the counter is bounded by the new space size.
+ memento_create_count->ClearFlag(HValue::kCanOverflow);
HStoreNamedField* store = Add<HStoreNamedField>(
allocation_site, HObjectAccess::ForAllocationSiteOffset(
AllocationSite::kMementoCreateCountOffset),
memento_create_count);
--
--
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