Changeset 34170 in webkit for trunk/JavaScriptCore

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).

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• VM/Machine.cpp (modified) (3 diffs)
• kjs/JSImmediate.h (modified) (1 diff)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2008-05-28  Alexey Proskuryakov  <[email protected]>
+
+        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).
+
 2008-05-27  Adam Roben  <[email protected]>
 

trunk/JavaScriptCore/VM/Machine.cpp

@@ -149 +149 @@
 //    <times> Add case: <t1> <t2>
 //    ---------------------------
-//    5627160 Add case: 1 1
-//    247427  Add case: 5 5
-//    20901   Add case: 5 6
-//    13978   Add case: 5 1
-//    4000    Add case: 1 5
-//    1       Add case: 3 5
+//    5626160 Add case: 3 3 (of these, 3637690 are for immediate values, 34373 of them for negative)
+//    247412  Add case: 5 5
+//    20900   Add case: 5 6
+//    13962   Add case: 5 3
+//    4000    Add case: 3 5
 
 static inline JSValue* jsAdd(ExecState* exec, JSValue* v1, JSValue* v2)
@@ -1177 +1176 @@
         int src1 = (++vPC)->u.operand;
         int src2 = (++vPC)->u.operand;
-        JSValue* result = jsAdd(exec, r[src1].u.jsValue, r[src2].u.jsValue);
+        JSValue* v1 = r[src1].u.jsValue;
+        JSValue* v2 = r[src2].u.jsValue;
+        JSValue* result;
+        if (JSImmediate::canDoFastAdditiveOperations(v1) && JSImmediate::canDoFastAdditiveOperations(v2))
+            result = JSImmediate::addImmediateNumbers(v1, v2);
+        else
+            result = jsAdd(exec, v1, v2);
         VM_CHECK_EXCEPTION();
         r[dst].u.jsValue = result;
@@ -1242 +1247 @@
         int src1 = (++vPC)->u.operand;
         int src2 = (++vPC)->u.operand;
-        JSValue* result = jsNumber(r[src1].u.jsValue->toNumber(exec) - r[src2].u.jsValue->toNumber(exec));
+        JSValue* v1 = r[src1].u.jsValue;
+        JSValue* v2 = r[src2].u.jsValue;
+        JSValue* result;
+        if (JSImmediate::canDoFastAdditiveOperations(v1) && JSImmediate::canDoFastAdditiveOperations(v2))
+            result = JSImmediate::subImmediateNumbers(v1, v2);
+        else
+            result = jsNumber(v1->toNumber(exec) - v2->toNumber(exec));
         VM_CHECK_EXCEPTION();
         r[dst].u.jsValue = result;

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*);