Changeset 34943 in webkit for trunk/JavaScriptCore/kjs/JSImmediate.h

Timestamp:

Jul 1, 2008, 9:21:43 PM (17 years ago)

Author:

[email protected]

Message:

2008-07-01 Geoffrey Garen <​[email protected]>

Reviewed by Oliver Hunt.

Optimized a[n] get and put for cases where n is an immediate unsigned
value.

SunSpider says 3.5% faster.

File:

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

trunk/JavaScriptCore/kjs/JSImmediate.h

@@ -70 +70 @@
     {
         return (getTag(v) == NumberType);
+    }
+    
+    static ALWAYS_INLINE bool isPositiveNumber(const JSValue* v)
+    {
+        // A single mask to check for the sign bit and the number tag all at once.
+        return (reinterpret_cast<uintptr_t>(v) & (0x80000000 | NumberType)) == NumberType;
     }
     
@@ -329 +335 @@
 ALWAYS_INLINE bool JSImmediate::getUInt32(const JSValue* v, uint32_t& i)
 {
-    const int32_t si = static_cast<int32_t>(unTag(v)) >> 2;
-    i = si;
-    return isNumber(v) & (si >= 0);
+    i = static_cast<uintptr_t>(unTag(v)) >> 2;
+    return isPositiveNumber(v);
 }