Changeset 6360 in webkit for trunk/JavaScriptCore/kjs/nodes.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/nodes.cpp (modified) (2 diffs)

trunk/JavaScriptCore/kjs/nodes.cpp

@@ -1371 +1371 @@
     Value v2 = expr->evaluate(exec);
     KJS_CHECKEXCEPTIONVALUE
-    int i1 = v1.toInt32(exec);
-    int i2 = v2.toInt32(exec);
+    int i1;
+    int i2;
     unsigned int ui;
     switch (oper) {
@@ -1388 +1388 @@
       break;
     case OpLShift:
+      i1 = v1.toInt32(exec);
+      i2 = v2.toInt32(exec);
       v = Number(i1 <<= i2);
       break;
     case OpRShift:
+      i1 = v1.toInt32(exec);
+      i2 = v2.toInt32(exec);
       v = Number(i1 >>= i2);
       break;
     case OpURShift:
       ui = v1.toUInt32(exec);
+      i2 = v2.toInt32(exec);
       v = Number(ui >>= i2);
       break;
     case OpAndEq:
+      i1 = v1.toInt32(exec);
+      i2 = v2.toInt32(exec);
       v = Number(i1 &= i2);
       break;
     case OpXOrEq:
+      i1 = v1.toInt32(exec);
+      i2 = v2.toInt32(exec);
       v = Number(i1 ^= i2);
       break;
     case OpOrEq:
+      i1 = v1.toInt32(exec);
+      i2 = v2.toInt32(exec);
       v = Number(i1 |= i2);
       break;