Changeset 29639 in webkit for trunk/JavaScriptCore/kjs/ustring.cpp

Timestamp:

Jan 18, 2008, 1:05:16 PM (17 years ago)

Author:

[email protected]

Message:

JavaScriptCore:

Reviewed by Geoff.

• Correctly report cost of appended strings to trigger GC.

• kjs/ustring.cpp: (KJS::): (KJS::UString::Rep::create): (KJS::UString::UString): Don't create unnecssary objects. (KJS::UString::cost): Report cost if necessary but also keep track of reported cost.
• kjs/ustring.h:

LayoutTests:

Reviewed by Geoff.

• Correctly report cost of appended strings to trigger GC.

• fast/js/garbage-collect-after-string-appends-expected.txt: Added.
• fast/js/garbage-collect-after-string-appends.html: Added.
• fast/js/resources/garbage-collect-after-string-appends.js: Added.

File:

• trunk/JavaScriptCore/kjs/ustring.cpp (modified) (6 diffs)

trunk/JavaScriptCore/kjs/ustring.cpp

@@ -78 +78 @@
 }
 
-// we'd rather not do shared substring append for small strings, since
-// this runs too much risk of a tiny initial string holding down a
-// huge buffer. This is also tuned to match the extra cost size, so we
-// don't ever share a buffer that wouldn't be over the extra cost
-// threshold already.
-// FIXME: this should be size_t but that would cause warnings until we
-// fix UString sizes to be size_t instad of int
-static const int minShareSize = Collector::minExtraCostSize / sizeof(UChar);
-
 COMPILE_ASSERT(sizeof(UChar) == 2, uchar_is_2_bytes)
 
@@ -174 +165 @@
 // Hack here to avoid a global with a constructor; point to an unsigned short instead of a UChar.
 static unsigned short almostUChar;
-UString::Rep UString::Rep::null = { 0, 0, 1, 0, 0, &UString::Rep::null, 0, 0, 0, 0, 0 };
-UString::Rep UString::Rep::empty = { 0, 0, 1, 0, 0, &UString::Rep::empty, reinterpret_cast<UChar*>(&almostUChar), 0, 0, 0, 0 };
+UString::Rep UString::Rep::null = { 0, 0, 1, 0, 0, &UString::Rep::null, 0, 0, 0, 0, 0, 0 };
+UString::Rep UString::Rep::empty = { 0, 0, 1, 0, 0, &UString::Rep::empty, 0, reinterpret_cast<UChar*>(&almostUChar), 0, 0, 0, 0 };
 const int normalStatBufferSize = 4096;
 static char *statBuffer = 0; // FIXME: This buffer is never deallocated.
@@ -202 +193 @@
   r->isIdentifier = 0;
   r->baseString = r;
+  r->reportedCost = 0;
   r->buf = d;
   r->usedCapacity = l;
@@ -231 +223 @@
   r->isIdentifier = 0;
   r->baseString = base.releaseRef();
+  r->reportedCost = 0;
   r->buf = 0;
   r->usedCapacity = 0;
@@ -498 +491 @@
     } else
         m_rep = &Rep::null;
-  } else if (-bOffset == b.usedPreCapacity() && bSize >= minShareSize && 4 * bSize >= aSize) {
+  } else if (-bOffset == b.usedPreCapacity() && bSize >= minShareSize  && 4 * bSize >= aSize) {
     // - b reaches the beginning of its buffer so it qualifies for shared prepend
     // - also, it's at least a quarter the length of a - prepending to a much shorter
@@ -1291 +1284 @@
 
 
+
 } // namespace KJS