Changeset 34171 in webkit for trunk/JavaScriptCore

Timestamp:

May 28, 2008, 3:48:04 AM (17 years ago)

Author:

[email protected]

Message:

Reviewed by Maciej.

Based on a patch by Oliver Hunt.

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

1.4% speedup on SunSpider.

• VM/Machine.cpp: (KJS::Machine::privateExecute):
• kjs/JSImmediate.h: (KJS::JSImmediate::incImmediateNumber): (KJS::JSImmediate::decImmediateNumber): Added fast paths for ++ and --.

(KJS::JSImmediate::canDoFastAdditiveOperations): Corrected a comment.

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• VM/Machine.cpp (modified) (4 diffs)
• kjs/JSImmediate.h (modified) (2 diffs)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2008-05-28  Alexey Proskuryakov  <[email protected]>
+
+        Reviewed by Maciej.
+
+        Based on a patch by Oliver Hunt.
+
+        https://bugs.webkit.org/show_bug.cgi?id=19180
+        speed up SunSpider by optimizing immediate number cases
+
+        1.4% speedup on SunSpider.
+
+        * VM/Machine.cpp:
+        (KJS::Machine::privateExecute):
+        * kjs/JSImmediate.h:
+        (KJS::JSImmediate::incImmediateNumber):
+        (KJS::JSImmediate::decImmediateNumber):
+        Added fast paths for ++ and --.
+
+        (KJS::JSImmediate::canDoFastAdditiveOperations): Corrected a comment.
+
 2008-05-28  Alexey Proskuryakov  <[email protected]>
 

trunk/JavaScriptCore/VM/Machine.cpp

@@ -1078 +1078 @@
         */
         int srcDst = (++vPC)->u.operand;
-        JSValue* result = jsNumber(r[srcDst].u.jsValue->toNumber(exec) + 1);
+        JSValue* v = r[srcDst].u.jsValue;
+        JSValue* result;
+        if (JSImmediate::canDoFastAdditiveOperations(v))
+            result = JSImmediate::incImmediateNumber(v);
+        else
+            result = jsNumber(v->toNumber(exec) + 1);
         VM_CHECK_EXCEPTION();
         r[srcDst].u.jsValue = result;
@@ -1092 +1097 @@
         */
         int srcDst = (++vPC)->u.operand;
-        JSValue* result = jsNumber(r[srcDst].u.jsValue->toNumber(exec) - 1);
+        JSValue* v = r[srcDst].u.jsValue;
+        JSValue* result;
+        if (JSImmediate::canDoFastAdditiveOperations(v))
+            result = JSImmediate::decImmediateNumber(v);
+        else
+            result = jsNumber(v->toNumber(exec) - 1);
         VM_CHECK_EXCEPTION();
         r[srcDst].u.jsValue = result;
@@ -1108 +1118 @@
         int dst = (++vPC)->u.operand;
         int srcDst = (++vPC)->u.operand;
-        JSValue* number = r[srcDst].u.jsValue->toJSNumber(exec);
+        JSValue* v = r[srcDst].u.jsValue;
+        JSValue* result;
+        JSValue* number;
+        if (JSImmediate::canDoFastAdditiveOperations(v)) {
+            number = v;
+            result = JSImmediate::incImmediateNumber(v);
+        } else {
+            number = r[srcDst].u.jsValue->toJSNumber(exec);
+            result = jsNumber(number->uncheckedGetNumber() + 1);
+        }
         VM_CHECK_EXCEPTION();
 
         r[dst].u.jsValue = number;
-        r[srcDst].u.jsValue = jsNumber(number->uncheckedGetNumber() + 1);
+        r[srcDst].u.jsValue = result;
 
         ++vPC;
@@ -1126 +1145 @@
         int dst = (++vPC)->u.operand;
         int srcDst = (++vPC)->u.operand;
-        JSValue* number = r[srcDst].u.jsValue->toJSNumber(exec);
+        JSValue* v = r[srcDst].u.jsValue;
+        JSValue* result;
+        JSValue* number;
+        if (JSImmediate::canDoFastAdditiveOperations(v)) {
+            number = v;
+            result = JSImmediate::decImmediateNumber(v);
+        } else {
+            number = r[srcDst].u.jsValue->toJSNumber(exec);
+            result = jsNumber(number->uncheckedGetNumber() - 1);
+        }
         VM_CHECK_EXCEPTION();
 
         r[dst].u.jsValue = number;
-        r[srcDst].u.jsValue = jsNumber(number->uncheckedGetNumber() - 1);
+        r[srcDst].u.jsValue = result;
 
         ++vPC;

trunk/JavaScriptCore/kjs/JSImmediate.h

@@ -121 +121 @@
     static ALWAYS_INLINE bool canDoFastAdditiveOperations(const JSValue* v)
     {
-        // Number is positive and an operation involving two of these can't overflow.
+        // Number is non-negative 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;
@@ -138 +138 @@
         ASSERT(canDoFastAdditiveOperations(v2));
         return reinterpret_cast<JSValue*>(reinterpret_cast<uintptr_t>(v1) - (reinterpret_cast<uintptr_t>(v2) & ~NumberType));
+    }
+
+    static ALWAYS_INLINE JSValue* incImmediateNumber(const JSValue* v)
+    {
+        ASSERT(canDoFastAdditiveOperations(v));
+        return reinterpret_cast<JSValue*>(reinterpret_cast<uintptr_t>(v) + TagMask + 1);
+    }
+
+    static ALWAYS_INLINE JSValue* decImmediateNumber(const JSValue* v)
+    {
+        ASSERT(canDoFastAdditiveOperations(v));
+        return reinterpret_cast<JSValue*>(reinterpret_cast<uintptr_t>(v) - (TagMask + 1));
     }