Title: [225315] trunk/Source/_javascript_Core
- Revision
- 225315
- Author
- fpi...@apple.com
- Date
- 2017-11-29 20:48:52 -0800 (Wed, 29 Nov 2017)
Log Message
CodeBlockSet::deleteUnmarkedAndUnreferenced can be a little more efficient
https://bugs.webkit.org/show_bug.cgi?id=180108
Reviewed by Saam Barati.
This was creating a vector of things to remove and then removing them. I think I remember writing
this code, and I did that because at the time we did not have removeAllMatching, which is
definitely better. This is a minuscule optimization for Speedometer. I wanted to land this
obvious improvement before I did more fundamental things to this code.
* heap/CodeBlockSet.cpp:
(JSC::CodeBlockSet::deleteUnmarkedAndUnreferenced):
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (225314 => 225315)
--- trunk/Source/_javascript_Core/ChangeLog 2017-11-30 04:39:50 UTC (rev 225314)
+++ trunk/Source/_javascript_Core/ChangeLog 2017-11-30 04:48:52 UTC (rev 225315)
@@ -1,3 +1,18 @@
+2017-11-28 Filip Pizlo <fpi...@apple.com>
+
+ CodeBlockSet::deleteUnmarkedAndUnreferenced can be a little more efficient
+ https://bugs.webkit.org/show_bug.cgi?id=180108
+
+ Reviewed by Saam Barati.
+
+ This was creating a vector of things to remove and then removing them. I think I remember writing
+ this code, and I did that because at the time we did not have removeAllMatching, which is
+ definitely better. This is a minuscule optimization for Speedometer. I wanted to land this
+ obvious improvement before I did more fundamental things to this code.
+
+ * heap/CodeBlockSet.cpp:
+ (JSC::CodeBlockSet::deleteUnmarkedAndUnreferenced):
+
2017-11-29 Filip Pizlo <fpi...@apple.com>
GC should support isoheaps
Modified: trunk/Source/_javascript_Core/heap/CodeBlockSet.cpp (225314 => 225315)
--- trunk/Source/_javascript_Core/heap/CodeBlockSet.cpp 2017-11-30 04:39:50 UTC (rev 225314)
+++ trunk/Source/_javascript_Core/heap/CodeBlockSet.cpp 2017-11-30 04:48:52 UTC (rev 225315)
@@ -28,6 +28,7 @@
#include "CodeBlock.h"
#include "JSCInlines.h"
+#include "SuperSampler.h"
#include <wtf/CommaPrinter.h>
namespace JSC {
@@ -74,19 +75,26 @@
void CodeBlockSet::deleteUnmarkedAndUnreferenced(VM& vm, CollectionScope scope)
{
LockHolder locker(&m_lock);
- Vector<CodeBlock*> unmarked;
+ // Destroying a CodeBlock takes about 1us on average in Speedometer. Full collections in Speedometer
+ // usually have ~2000 CodeBlocks to process. The time it takes to process the whole list varies a
+ // lot. In one extreme case I saw 18ms (on my fast MBP).
+ //
+ // FIXME: use Subspace instead of HashSet and adopt Subspace-based constraint solving. This may
+ // remove the need to eagerly destruct CodeBlocks.
+ // https://bugs.webkit.org/show_bug.cgi?id=180089
+ //
+ // FIXME: make CodeBlock::~CodeBlock a lot faster. It seems insane for that to take 1us or more.
+ // https://bugs.webkit.org/show_bug.cgi?id=180109
+
auto consider = [&] (HashSet<CodeBlock*>& set) {
- for (CodeBlock* codeBlock : set) {
- if (Heap::isMarked(codeBlock))
- continue;;
- unmarked.append(codeBlock);
- }
- for (CodeBlock* codeBlock : unmarked) {
- codeBlock->structure(vm)->classInfo()->methodTable.destroy(codeBlock);
- set.remove(codeBlock);
- }
- unmarked.shrink(0);
+ set.removeIf(
+ [&] (CodeBlock* codeBlock) -> bool {
+ if (Heap::isMarked(codeBlock))
+ return false;
+ codeBlock->structure(vm)->classInfo()->methodTable.destroy(codeBlock);
+ return true;
+ });
};
switch (scope) {
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