Changeset 51671 in webkit for trunk/JavaScriptCore/jit

Timestamp:

Dec 3, 2009, 6:15:18 PM (15 years ago)

Author:

[email protected]

Message:

​https://bugs.webkit.org/show_bug.cgi?id=32136
Add a rope representation to JSString. Presently JSString always holds its data in UString form.
Instead, allow the result of a string concatenation to be represented in a tree form - with a
variable sized, reference-counted rope node retaining a set of UString::Reps (or other rope nopes).

Reviewed by Oliver "Brraaaaiiiinnnnnzzzzzzzz" Hunt.

Strings must still currently be resolved down to a flat UString representation before being used,
but by holding the string in a rope representation during construction we can avoid copying data
until we know the final size of the string.

~2% progression on SunSpider (~25% on date-format-xparb, ~20% on string-validate-input).

• JavaScriptCore.exp:

• Update exports.

• interpreter/Interpreter.cpp:

(JSC::Interpreter::privateExecute):

• Make use of new JSString::length() method to avoid prematurely resolving ropes.

• jit/JITOpcodes.cpp:

(JSC::JIT::privateCompileCTIMachineTrampolines):

• Switch the string length trampoline to read the length directly from JSString::m_length, rather than from the JSString's UString::Rep's 'len' property.

• jit/JITStubs.cpp:

(JSC::DEFINE_STUB_FUNCTION):

• Modify op_add such that addition of two strings, where either or both strings are already in rope representation, produces a rope as a result.

• runtime/JSString.cpp:

(JSC::JSString::Rope::~Rope):
(JSC::copyChars):
(JSC::JSString::resolveRope):
(JSC::JSString::getPrimitiveNumber):
(JSC::JSString::toBoolean):
(JSC::JSString::toNumber):
(JSC::JSString::toString):
(JSC::JSString::toThisString):
(JSC::JSString::getStringPropertyDescriptor):

• runtime/JSString.h:

(JSC::JSString::Rope::Fiber::Fiber):
(JSC::JSString::Rope::Fiber::destroy):
(JSC::JSString::Rope::Fiber::isRope):
(JSC::JSString::Rope::Fiber::rope):
(JSC::JSString::Rope::Fiber::string):
(JSC::JSString::Rope::create):
(JSC::JSString::Rope::initializeFiber):
(JSC::JSString::Rope::ropeLength):
(JSC::JSString::Rope::stringLength):
(JSC::JSString::Rope::fibers):
(JSC::JSString::Rope::Rope):
(JSC::JSString::Rope::operator new):
(JSC::JSString::JSString):
(JSC::JSString::value):
(JSC::JSString::length):
(JSC::JSString::isRope):
(JSC::JSString::rope):
(JSC::JSString::string):
(JSC::JSString::canGetIndex):
(JSC::jsSingleCharacterSubstring):
(JSC::JSString::getIndex):
(JSC::jsSubstring):
(JSC::JSString::getStringPropertySlot):

• Add rope form.

• runtime/Operations.h:

(JSC::jsAdd):
(JSC::concatenateStrings):

• Update string concatenation, and addition of ropes, to produce ropes.

• runtime/StringObject.cpp:

(JSC::StringObject::getOwnPropertyNames):

• Make use of new JSString::length() method to avoid prematurely resolving ropes.

Location:

trunk/JavaScriptCore/jit

Files:

• JITOpcodes.cpp (modified) (2 diffs)
• JITStubs.cpp (modified) (1 diff)

trunk/JavaScriptCore/jit/JITOpcodes.cpp

@@ -53 +53 @@
 
     // Checks out okay! - get the length from the Ustring.
-    loadPtr(Address(regT0, OBJECT_OFFSETOF(JSString, m_value) + OBJECT_OFFSETOF(UString, m_rep)), regT2);
-    load32(Address(regT2, OBJECT_OFFSETOF(UString::Rep, len)), regT2);
+    load32(Address(regT0, OBJECT_OFFSETOF(JSString, m_length)), regT2);
 
     Jump string_failureCases3 = branch32(Above, regT2, Imm32(INT_MAX));
@@ -1594 +1593 @@
 
     // Checks out okay! - get the length from the Ustring.
-    loadPtr(Address(regT0, OBJECT_OFFSETOF(JSString, m_value) + OBJECT_OFFSETOF(UString, m_rep)), regT0);
-    load32(Address(regT0, OBJECT_OFFSETOF(UString::Rep, len)), regT0);
+    load32(Address(regT0, OBJECT_OFFSETOF(JSString, m_length)), regT0);
 
     Jump string_failureCases3 = branch32(Above, regT0, Imm32(JSImmediate::maxImmediateInt));

trunk/JavaScriptCore/jit/JITStubs.cpp

@@ -1044 +1044 @@
     bool leftIsString = v1.isString();
     if (leftIsString && v2.isString()) {
+        if (asString(v1)->isRope() || asString(v2)->isRope()) {
+            RefPtr<JSString::Rope> rope = JSString::Rope::create(2);
+            rope->initializeFiber(0, asString(v1));
+            rope->initializeFiber(1, asString(v2));
+            JSGlobalData* globalData = &callFrame->globalData();
+            return JSValue::encode(new (globalData) JSString(globalData, rope.release()));
+        }
+
         RefPtr<UString::Rep> value = concatenate(asString(v1)->value().rep(), asString(v2)->value().rep());
         if (UNLIKELY(!value)) {