Changeset 6360 in webkit for trunk/JavaScriptCore/kjs/identifier.cpp

Timestamp:

Apr 13, 2004, 7:33:59 PM (21 years ago)

Author:

mjs

Message:

Reviewed by Darin.

• fixed <rdar://problem/3600695>: String manipulation in JavaScript 24fun test is very slow (slow)
• fixed <rdar://problem/3600691>: Table generation test is really slow
• fixed <rdar://problem/3600661>: 24fun date test is really slow

80% speedup on the string test, lesser speedups on the other two.

Two different optimizations here:

1) Avoid large overhead of scanning strings to see if they are all
ASCII before numeric conversion.

• kjs/nodes.cpp: (AssignNode::evaluate): Don't convert to integer until we know for sure the operation will need it. Attempting to convert strings to numbers is a waste when they are being appended with +=.

2) Avoid huge cost of appending strings.

This is done by allowing multiple strings to share a buffer but
actually use different ranges of it. The first time a string is
appended to, we start leaving at least 10% extra space in the
buffer, so doing N appends to the same string takes O(log N)
mallocs instead of O(N).

• kjs/identifier.cpp: (KJS::Identifier::equal): (KJS::Identifier::add):
• kjs/ustring.cpp: (KJS::): (KJS::UCharReference::operator=): (KJS::UCharReference::ref): (KJS::UString::Rep::create): (KJS::UString::Rep::destroy): (KJS::UString::expandedSize): (KJS::UString::usedCapacity): (KJS::UString::expandCapacity): (KJS::UString::UString): (KJS::UString::null): (KJS::UString::append): (KJS::UString::operator=): (KJS::UString::toStrictUInt32): (KJS::UString::detach): (KJS::KJS::operator==):
• kjs/ustring.h: (KJS::UString::Rep::data): (KJS::UString::Rep::hash):

File:

• trunk/JavaScriptCore/kjs/identifier.cpp (modified) (7 diffs)

trunk/JavaScriptCore/kjs/identifier.cpp

@@ -68 +68 @@
 {
     int length = r->len;
-    const UChar *d = r->dat;
+    const UChar *d = r->data();
     for (int i = 0; i != length; ++i)
         if (d[i].uc != (unsigned char)s[i])
@@ -79 +79 @@
     if (r->len != length)
         return false;
-    const UChar *d = r->dat;
+    const UChar *d = r->data();
     for (int i = 0; i != length; ++i)
         if (d[i].uc != s[i].uc)
@@ -91 +91 @@
     if (length != b->len)
         return false;
-    const UChar *d = r->dat;
-    const UChar *s = b->dat;
+    const UChar *d = r->data();
+    const UChar *s = b->data();
     for (int i = 0; i != length; ++i)
         if (d[i].uc != s[i].uc)
@@ -123 +123 @@
     }
     
-    UChar *d = new UChar[length];
+    UChar *d = static_cast<UChar *>(malloc(sizeof(UChar) * length));
     for (int j = 0; j != length; j++)
         d[j] = c[j];
     
-    UString::Rep *r = new UString::Rep;
-    r->dat = d;
-    r->len = length;
-    r->capacity = UString::Rep::capacityForIdentifier;
+    UString::Rep *r = UString::Rep::create(d, length);
+    r->isIdentifier = 1;
     r->rc = 0;
     r->_hash = hash;
@@ -164 +162 @@
     }
     
-    UChar *d = new UChar[length];
+    UChar *d = static_cast<UChar *>(malloc(sizeof(UChar) * length));
     for (int j = 0; j != length; j++)
         d[j] = s[j];
     
-    UString::Rep *r = new UString::Rep;
-    r->dat = d;
-    r->len = length;
-    r->capacity = UString::Rep::capacityForIdentifier;
+    UString::Rep *r = UString::Rep::create(d, length);
+    r->isIdentifier = 1;
     r->rc = 0;
     r->_hash = hash;
@@ -186 +182 @@
 UString::Rep *Identifier::add(UString::Rep *r)
 {
-    if (r->capacity == UString::Rep::capacityForIdentifier)
+    if (r->isIdentifier)
         return r;
     if (r->len == 0)
@@ -207 +203 @@
     }
     
-    r->capacity = UString::Rep::capacityForIdentifier;
+    r->isIdentifier = 1;
     
     _table[i] = r;