Changeset 44641 in webkit for trunk/JavaScriptCore

Timestamp:

Jun 12, 2009, 5:41:03 PM (16 years ago)

Author:

[email protected]

Message:

JavaScriptCore:

2009-06-12 David Levin <​[email protected]>

Reviewed by Darin Adler.

UString shouldn't create sharedBuffer for SmallStrings.
​https://bugs.webkit.org/show_bug.cgi?id=26360

The methods changed are not used by JSC, so there is no JS perf impact. However,
there is a potential DOM perf impact, so I re-ran several of the tests that
I ran previously and ensured that the perf stay the same which caused me to
adjust the minLengthToShare.

• JavaScriptCore.exp:
• runtime/UString.cpp: (JSC::UString::Rep::sharedBuffer):

Determines if the buffer being shared is big enough before doing so.
Previously, BaseString::sharedBuffer was called but it would only know
the length of the base string (BaseString::len) which may not be the same
as the string being shared (Rep::len).

(JSC::UString::BaseString::sharedBuffer):

This is now only be used by Rep::sharedBuffer. which does the length check.

• runtime/UString.h:

WebCore:

2009-06-12 David Levin <​[email protected]>

Reviewed by Darin Adler.

UString shouldn't create sharedBuffer for SmallStrings.
​https://bugs.webkit.org/show_bug.cgi?id=26347

Change the call to use the method UString::Rep::sharedBuffer due
to changes in UString.

No noticable change in behavior, so no test.

• platform/text/StringImpl.cpp: (WebCore::StringImpl::create):

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• JavaScriptCore.exp (modified) (1 diff)
• runtime/UString.cpp (modified) (3 diffs)
• runtime/UString.h (modified) (3 diffs)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2009-06-12  David Levin  <[email protected]>
+
+        Reviewed by Darin Adler.
+
+        UString shouldn't create sharedBuffer for SmallStrings.
+        https://bugs.webkit.org/show_bug.cgi?id=26360
+
+        The methods changed are not used by JSC, so there is no JS perf impact.  However,
+        there is a potential DOM perf impact, so I re-ran several of the tests that
+        I ran previously and ensured that the perf stay the same which caused me to
+        adjust the minLengthToShare.
+
+        * JavaScriptCore.exp:
+        * runtime/UString.cpp:
+        (JSC::UString::Rep::sharedBuffer):
+            Determines if the buffer being shared is big enough before doing so.
+            Previously, BaseString::sharedBuffer was called but it would only know
+            the length of the base string (BaseString::len) which may not be the same
+            as the string being shared (Rep::len).
+        (JSC::UString::BaseString::sharedBuffer):
+            This is now only be used by Rep::sharedBuffer. which does the length check.
+        * runtime/UString.h:
+
 2009-06-12  Dimitri Glazkov  <[email protected]>
 

trunk/JavaScriptCore/JavaScriptCore.exp

@@ -218 +218 @@
 __ZN3JSC7Profile7excludeEPKNS_11ProfileNodeE
 __ZN3JSC7Profile7forEachEMNS_11ProfileNodeEFvvE
-__ZN3JSC7UString10BaseString12sharedBufferEv
+__ZN3JSC7UString3Rep12sharedBufferEv
 __ZN3JSC7UString3Rep11computeHashEPKci
 __ZN3JSC7UString3Rep11computeHashEPKti

trunk/JavaScriptCore/runtime/UString.cpp

@@ -64 +64 @@
 
 // This number must be at least 2 to avoid sharing empty, null as well as 1 character strings from SmallStrings.
-static const int minLengthToShare = 30;
+static const int minLengthToShare = 10;
 
 static inline size_t overflowIndicator() { return std::numeric_limits<size_t>::max(); }
@@ -244 +244 @@
 }
 
+UString::SharedUChar* UString::Rep::sharedBuffer()
+{
+    UString::BaseString* base = baseString();
+    if (len < minLengthToShare)
+        return 0;
+
+    return base->sharedBuffer();
+}
+
 void UString::Rep::destroy()
 {
@@ -386 +395 @@
 UString::SharedUChar* UString::BaseString::sharedBuffer()
 {
-
-    if (len < minLengthToShare)
-        return 0;
-
     if (!m_sharedBuffer)
         setSharedBuffer(SharedUChar::create(new OwnFastMallocPtr<UChar>(buf)));

trunk/JavaScriptCore/runtime/UString.h

@@ -108 +108 @@
             static PassRefPtr<Rep> create(UChar*, int, PassRefPtr<SharedUChar>);
 
+            SharedUChar* sharedBuffer();
             void destroy();
 
@@ -193 +194 @@
             bool isShared() { return rc != 1 || isBufferReadOnly(); }
             void setSharedBuffer(PassRefPtr<SharedUChar>);
-            SharedUChar* sharedBuffer();
 
             bool isBufferReadOnly()
@@ -225 +225 @@
             }
 
+            SharedUChar* sharedBuffer();
             bool slowIsBufferReadOnly();