Revision: 20489
Author: dslo...@chromium.org
Date: Thu Apr 3 16:25:05 2014 UTC
Log: Harden IsMoreGeneralElementsKindTransition.
R=verwa...@chromium.org
Review URL: https://codereview.chromium.org/213783004
http://code.google.com/p/v8/source/detail?r=20489
Modified:
/branches/bleeding_edge/src/elements-kind.cc
=======================================
--- /branches/bleeding_edge/src/elements-kind.cc Tue Apr 1 16:41:35 2014
UTC
+++ /branches/bleeding_edge/src/elements-kind.cc Thu Apr 3 16:25:05 2014
UTC
@@ -178,6 +178,11 @@
}
+static inline bool IsFastTransitionTarget(ElementsKind elements_kind) {
+ return IsFastElementsKind(elements_kind) ||
+ elements_kind == DICTIONARY_ELEMENTS;
+}
+
bool IsMoreGeneralElementsKindTransition(ElementsKind from_kind,
ElementsKind to_kind) {
if (IsTypedArrayElementsKind(from_kind) ||
@@ -193,26 +198,29 @@
return false;
}
}
- switch (from_kind) {
- case FAST_SMI_ELEMENTS:
- return to_kind != FAST_SMI_ELEMENTS;
- case FAST_HOLEY_SMI_ELEMENTS:
- return to_kind != FAST_SMI_ELEMENTS &&
- to_kind != FAST_HOLEY_SMI_ELEMENTS;
- case FAST_DOUBLE_ELEMENTS:
- return to_kind != FAST_SMI_ELEMENTS &&
- to_kind != FAST_HOLEY_SMI_ELEMENTS &&
- to_kind != FAST_DOUBLE_ELEMENTS;
- case FAST_HOLEY_DOUBLE_ELEMENTS:
- return to_kind == FAST_ELEMENTS ||
- to_kind == FAST_HOLEY_ELEMENTS;
- case FAST_ELEMENTS:
- return to_kind == FAST_HOLEY_ELEMENTS;
- case FAST_HOLEY_ELEMENTS:
- return false;
- default:
- return false;
+ if (IsFastElementsKind(from_kind) && IsFastTransitionTarget(to_kind)) {
+ switch (from_kind) {
+ case FAST_SMI_ELEMENTS:
+ return to_kind != FAST_SMI_ELEMENTS;
+ case FAST_HOLEY_SMI_ELEMENTS:
+ return to_kind != FAST_SMI_ELEMENTS &&
+ to_kind != FAST_HOLEY_SMI_ELEMENTS;
+ case FAST_DOUBLE_ELEMENTS:
+ return to_kind != FAST_SMI_ELEMENTS &&
+ to_kind != FAST_HOLEY_SMI_ELEMENTS &&
+ to_kind != FAST_DOUBLE_ELEMENTS;
+ case FAST_HOLEY_DOUBLE_ELEMENTS:
+ return to_kind == FAST_ELEMENTS ||
+ to_kind == FAST_HOLEY_ELEMENTS;
+ case FAST_ELEMENTS:
+ return to_kind == FAST_HOLEY_ELEMENTS;
+ case FAST_HOLEY_ELEMENTS:
+ return false;
+ default:
+ return false;
+ }
}
+ return false;
}
--
--
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