Changeset 34265 in webkit for trunk/JavaScriptCore/VM/Machine.cpp

Timestamp:

May 30, 2008, 1:10:38 PM (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

Also fixed a JavaScriptCore regression seen on PowerPC - we didn't clip left shift
parameter to 0...31.

0.5% improvement on SunSpider overall, although a 8.5 regression on bitops-3bit-bits-in-byte.

• VM/Machine.cpp: (KJS::Machine::privateExecute): Added fast paths for >>> and <<.

• kjs/JSImmediate.h: (KJS::JSImmediate::toTruncatedUInt32): Added. Same as getTruncatedInt32, but casts the result to unsigned.

File:

• trunk/JavaScriptCore/VM/Machine.cpp (modified) (2 diffs)

trunk/JavaScriptCore/VM/Machine.cpp

@@ -1319 +1319 @@
         JSValue* val = r[(++vPC)->u.operand].u.jsValue;
         JSValue* shift = r[(++vPC)->u.operand].u.jsValue;
-        JSValue* result = jsNumber((val->toInt32(exec)) << (shift->toUInt32(exec)));
-        VM_CHECK_EXCEPTION();
+        JSValue* result;
+        if (JSImmediate::areBothImmediateNumbers(val, shift))
+            result = jsNumber(JSImmediate::getTruncatedInt32(val) << (JSImmediate::toTruncatedUInt32(shift) & 0x1f));
+        else {
+            result = jsNumber((val->toInt32(exec)) << (shift->toUInt32(exec) & 0x1f));
+            VM_CHECK_EXCEPTION();
+        }
         dst = result;
         
@@ -1359 +1364 @@
         JSValue* shift = r[(++vPC)->u.operand].u.jsValue;
         JSValue* result;
-        result = jsNumber((val->toUInt32(exec)) >> (shift->toUInt32(exec) & 0x1f));
-        VM_CHECK_EXCEPTION();
+        if (JSImmediate::areBothImmediateNumbers(val, shift) && !JSImmediate::isNegative(val))
+            result = JSImmediate::rightShiftImmediateNumbers(val, shift);
+        else {
+            result = jsNumber((val->toUInt32(exec)) >> (shift->toUInt32(exec) & 0x1f));
+            VM_CHECK_EXCEPTION();
+        }
         dst = result;