Title: [201314] trunk/Source/WTF
- Revision
- 201314
- Author
- [email protected]
- Date
- 2016-05-23 19:10:16 -0700 (Mon, 23 May 2016)
Log Message
Speed up move of vectors of POD types that have an inline buffer
https://bugs.webkit.org/show_bug.cgi?id=158003
Reviewed by Benjamin Poulain.
When moving a vector of POD types that have an inline buffer, we would
call std::swap() on the inline buffers. This unnecessarily slow because:
1. It does not consider the vector size, and therefore may end up doing
more work than necessary when the inline buffer is not full.
2. In the "move" case, the destination buffer is completely empty so
we don't really want a swap. We merely want the move the content of
the source's inline buffer into the destination's one.
Instead of calling std::swap(), we now call swapInlineBuffers() which
was already used for non-POD types. swapInlineBuffers() will do just
what we want in the "move" case because swapBound is going to be 0.
As a result, we will only move the content of the source buffer into
the destination one. Also swapInlineBuffers() is aware of the source
vector's size so it will only move what's strictly needed.
This seems to be a 2% progression on Dromaeo DOM attributes test.
* wtf/Vector.h:
(WTF::VectorBuffer::swapInlineBuffer):
Modified Paths
Diff
Modified: trunk/Source/WTF/ChangeLog (201313 => 201314)
--- trunk/Source/WTF/ChangeLog 2016-05-24 01:54:51 UTC (rev 201313)
+++ trunk/Source/WTF/ChangeLog 2016-05-24 02:10:16 UTC (rev 201314)
@@ -1,3 +1,30 @@
+2016-05-23 Chris Dumez <[email protected]>
+
+ Speed up move of vectors of POD types that have an inline buffer
+ https://bugs.webkit.org/show_bug.cgi?id=158003
+
+ Reviewed by Benjamin Poulain.
+
+ When moving a vector of POD types that have an inline buffer, we would
+ call std::swap() on the inline buffers. This unnecessarily slow because:
+ 1. It does not consider the vector size, and therefore may end up doing
+ more work than necessary when the inline buffer is not full.
+ 2. In the "move" case, the destination buffer is completely empty so
+ we don't really want a swap. We merely want the move the content of
+ the source's inline buffer into the destination's one.
+
+ Instead of calling std::swap(), we now call swapInlineBuffers() which
+ was already used for non-POD types. swapInlineBuffers() will do just
+ what we want in the "move" case because swapBound is going to be 0.
+ As a result, we will only move the content of the source buffer into
+ the destination one. Also swapInlineBuffers() is aware of the source
+ vector's size so it will only move what's strictly needed.
+
+ This seems to be a 2% progression on Dromaeo DOM attributes test.
+
+ * wtf/Vector.h:
+ (WTF::VectorBuffer::swapInlineBuffer):
+
2016-05-22 Dan Bernstein <[email protected]>
Added NSEventMaskMouseMoved to AppKitCompatibilityDeclarations.h.
Modified: trunk/Source/WTF/wtf/Vector.h (201313 => 201314)
--- trunk/Source/WTF/wtf/Vector.h 2016-05-24 01:54:51 UTC (rev 201313)
+++ trunk/Source/WTF/wtf/Vector.h 2016-05-24 02:10:16 UTC (rev 201314)
@@ -538,11 +538,7 @@
{
// FIXME: We could make swap part of VectorTypeOperations
// https://bugs.webkit.org/show_bug.cgi?id=128863
-
- if (std::is_pod<T>::value)
- std::swap(m_inlineBuffer, other.m_inlineBuffer);
- else
- swapInlineBuffers(inlineBuffer(), other.inlineBuffer(), mySize, otherSize);
+ swapInlineBuffers(inlineBuffer(), other.inlineBuffer(), mySize, otherSize);
}
static void swapInlineBuffers(T* left, T* right, size_t leftSize, size_t rightSize)
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