Title: [130315] trunk/Source/_javascript_Core
- Revision
- 130315
- Author
- fpi...@apple.com
- Date
- 2012-10-03 13:03:20 -0700 (Wed, 03 Oct 2012)
Log Message
Array.splice should be fast when it is used to remove elements other than the very first
https://bugs.webkit.org/show_bug.cgi?id=98236
Reviewed by Michael Saboff.
Applied the same technique that was used to optimize the unshift case of splice in
http://trac.webkit.org/changeset/129676. This is a >20x speed-up on programs that
use splice for element removal.
* runtime/ArrayPrototype.cpp:
(JSC::shift):
* runtime/JSArray.cpp:
(JSC::JSArray::shiftCount):
* runtime/JSArray.h:
(JSArray):
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (130314 => 130315)
--- trunk/Source/_javascript_Core/ChangeLog 2012-10-03 20:00:47 UTC (rev 130314)
+++ trunk/Source/_javascript_Core/ChangeLog 2012-10-03 20:03:20 UTC (rev 130315)
@@ -1,3 +1,21 @@
+2012-10-03 Filip Pizlo <fpi...@apple.com>
+
+ Array.splice should be fast when it is used to remove elements other than the very first
+ https://bugs.webkit.org/show_bug.cgi?id=98236
+
+ Reviewed by Michael Saboff.
+
+ Applied the same technique that was used to optimize the unshift case of splice in
+ http://trac.webkit.org/changeset/129676. This is a >20x speed-up on programs that
+ use splice for element removal.
+
+ * runtime/ArrayPrototype.cpp:
+ (JSC::shift):
+ * runtime/JSArray.cpp:
+ (JSC::JSArray::shiftCount):
+ * runtime/JSArray.h:
+ (JSArray):
+
2012-09-16 Mark Hahnenberg <mhahnenb...@apple.com>
Delayed structure sweep can leak structures without bound
Modified: trunk/Source/_javascript_Core/runtime/ArrayPrototype.cpp (130314 => 130315)
--- trunk/Source/_javascript_Core/runtime/ArrayPrototype.cpp 2012-10-03 20:00:47 UTC (rev 130314)
+++ trunk/Source/_javascript_Core/runtime/ArrayPrototype.cpp 2012-10-03 20:03:20 UTC (rev 130315)
@@ -202,9 +202,9 @@
ASSERT(header <= length);
ASSERT(currentCount <= (length - header));
- if (!header && isJSArray(thisObj)) {
+ if (isJSArray(thisObj)) {
JSArray* array = asArray(thisObj);
- if (array->length() == length && asArray(thisObj)->shiftCount(exec, count))
+ if (array->length() == length && asArray(thisObj)->shiftCount(exec, header, count))
return;
}
Modified: trunk/Source/_javascript_Core/runtime/JSArray.cpp (130314 => 130315)
--- trunk/Source/_javascript_Core/runtime/JSArray.cpp 2012-10-03 20:00:47 UTC (rev 130314)
+++ trunk/Source/_javascript_Core/runtime/JSArray.cpp 2012-10-03 20:03:20 UTC (rev 130315)
@@ -505,7 +505,7 @@
}
}
-bool JSArray::shiftCount(ExecState* exec, unsigned count)
+bool JSArray::shiftCount(ExecState* exec, unsigned startIndex, unsigned count)
{
ASSERT(count > 0);
@@ -522,20 +522,44 @@
if (!oldLength)
return true;
+ unsigned length = oldLength - count;
+
storage->m_numValuesInVector -= count;
- storage->setLength(oldLength - count);
+ storage->setLength(length);
unsigned vectorLength = storage->vectorLength();
+ if (!vectorLength)
+ return true;
+
+ if (startIndex >= vectorLength)
+ return true;
+
+ if (startIndex + count > vectorLength)
+ count = vectorLength - startIndex;
+
+ unsigned usedVectorLength = min(vectorLength, oldLength);
+
+ vectorLength -= count;
+ storage->setVectorLength(vectorLength);
+
if (vectorLength) {
- count = min(vectorLength, (unsigned)count);
-
- vectorLength -= count;
- storage->setVectorLength(vectorLength);
-
- if (vectorLength) {
+ if (startIndex < usedVectorLength - (startIndex + count)) {
+ if (startIndex) {
+ memmove(
+ storage->m_vector + count,
+ storage->m_vector,
+ sizeof(JSValue) * startIndex);
+ }
m_butterfly = m_butterfly->shift(structure(), count);
storage = m_butterfly->arrayStorage();
storage->m_indexBias += count;
+ } else {
+ memmove(
+ storage->m_vector + startIndex,
+ storage->m_vector + startIndex + count,
+ sizeof(JSValue) * (usedVectorLength - (startIndex + count)));
+ for (unsigned i = usedVectorLength - count; i < usedVectorLength; ++i)
+ storage->m_vector[i].clear();
}
}
return true;
Modified: trunk/Source/_javascript_Core/runtime/JSArray.h (130314 => 130315)
--- trunk/Source/_javascript_Core/runtime/JSArray.h 2012-10-03 20:00:47 UTC (rev 130314)
+++ trunk/Source/_javascript_Core/runtime/JSArray.h 2012-10-03 20:03:20 UTC (rev 130315)
@@ -71,8 +71,8 @@
void push(ExecState*, JSValue);
JSValue pop(ExecState*);
- bool shiftCount(ExecState*, unsigned count);
- bool unshiftCount(ExecState*, unsigned, unsigned);
+ bool shiftCount(ExecState*, unsigned startIndex, unsigned count);
+ bool unshiftCount(ExecState*, unsigned startIndex, unsigned count);
void fillArgList(ExecState*, MarkedArgumentBuffer&);
void copyToArguments(ExecState*, CallFrame*, uint32_t length);
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