Changeset 34170 in webkit for trunk/JavaScriptCore/kjs/JSImmediate.h

Timestamp:

May 28, 2008, 2:47:29 AM (17 years ago)

Author:

[email protected]

Message:

Reviewed by Darin.

​https://bugs.webkit.org/show_bug.cgi?id=19180
speed up SunSpider by optimizing immediate number cases

2% speedup overall, maximum 10% on controlflow-recursive and bitops-3bit-bits-in-byte,
but a 4% regression on bitops-bits-in-byte and bitops-bitwise-and.

• kjs/JSImmediate.h: (KJS::JSImmediate::canDoFastAdditiveOperations): (KJS::JSImmediate::addImmediateNumbers): (KJS::JSImmediate::subImmediateNumbers): Added fast cases that work with positive values less than 2^30.

• VM/Machine.cpp: (KJS::Machine::privateExecute): Use the above operations. Also updated SunSpider frequencies with my results (looks like tag values have changed, not sure what caused the minor variation in actual frequencies).

File:

• trunk/JavaScriptCore/kjs/JSImmediate.h (modified) (1 diff)

trunk/JavaScriptCore/kjs/JSImmediate.h

@@ -119 +119 @@
     }
 
+    static ALWAYS_INLINE bool canDoFastAdditiveOperations(const JSValue* v)
+    {
+        // Number is positive and an operation involving two of these can't overflow.
+        // Checking for allowed negative numbers takes more time than it's worth on SunSpider.
+        return (reinterpret_cast<uintptr_t>(v) & (NumberType + (3 << 30))) == NumberType;
+    }
+
+    static ALWAYS_INLINE JSValue* addImmediateNumbers(const JSValue* v1, const JSValue* v2)
+    {
+        ASSERT(canDoFastAdditiveOperations(v1));
+        ASSERT(canDoFastAdditiveOperations(v2));
+        return reinterpret_cast<JSValue*>(reinterpret_cast<uintptr_t>(v1) + (reinterpret_cast<uintptr_t>(v2) & ~NumberType));
+    }
+
+    static ALWAYS_INLINE JSValue* subImmediateNumbers(const JSValue* v1, const JSValue* v2)
+    {
+        ASSERT(canDoFastAdditiveOperations(v1));
+        ASSERT(canDoFastAdditiveOperations(v2));
+        return reinterpret_cast<JSValue*>(reinterpret_cast<uintptr_t>(v1) - (reinterpret_cast<uintptr_t>(v2) & ~NumberType));
+    }
+
     static double toDouble(const JSValue*);
     static bool toBoolean(const JSValue*);