Changeset 34258 in webkit for trunk/JavaScriptCore/kjs/JSImmediate.h

Timestamp:

May 30, 2008, 2:10:42 AM (17 years ago)

Author:

[email protected]

Message:

Reviewed by Oliver Hunt.

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

Also fixed three JavaScriptCore regressions seen on PowerPC - we didn't clip right shift
parameter to 0...31.

1.6% improvement on SunSpider, without significant regressions on any tests.

• VM/Machine.cpp: (KJS::Machine::privateExecute): Added fast paths for >>, ==, ===, !=, !==. Changed order of memory accesses in many cases, making them less dependent on gcc's ability to properly assign registers. With this, I could move exception checks back into slow code paths, and saw less randomness in general.

• kjs/JSImmediate.h: (KJS::JSImmediate::rightShiftImmediateNumbers): Added.

File:

• trunk/JavaScriptCore/kjs/JSImmediate.h (modified) (2 diffs)

trunk/JavaScriptCore/kjs/JSImmediate.h

@@ -81 +81 @@
     {
         return (getTag(v) == UndefinedType);
+    }
+
+    static bool isNegative(const JSValue* v)
+    {
+        ASSERT(isNumber(v));
+        return reinterpret_cast<uintptr_t>(v) & 0x80000000;
     }
 
@@ -119 +125 @@
     }
 
+    static ALWAYS_INLINE JSValue* rightShiftImmediateNumbers(const JSValue* val, const JSValue* shift)
+    {
+        ASSERT(areBothImmediateNumbers(val, shift));
+        return reinterpret_cast<JSValue*>((reinterpret_cast<intptr_t>(val) >> ((reinterpret_cast<uintptr_t>(shift) >> 2) & 0x1f)) | NumberType);
+    }
+
     static ALWAYS_INLINE bool canDoFastAdditiveOperations(const JSValue* v)
     {