Changeset 19631 in webkit

Timestamp:

Feb 14, 2007, 3:42:44 PM (18 years ago)

Author:

andersca

Message:

Reviewed by Darin.

Add new canCompareWithMemcmp vector trait and use it to determine whether
operator== can use memcmp.

• wtf/Vector.h: (WTF::): (WTF::VectorTypeOperations::compare): (WTF::operator==):
• wtf/VectorTraits.h: (WTF::):

Location:

trunk/JavaScriptCore

Files:

• ChangeLog (modified) (1 diff)
• wtf/Vector.h (modified) (3 diffs)
• wtf/VectorTraits.h (modified) (4 diffs)

trunk/JavaScriptCore/ChangeLog

@@ +1 @@
+2007-02-14  Anders Carlsson  <acarlsson@apple.com>
+
+        Reviewed by Darin.
+
+        Add new canCompareWithMemcmp vector trait and use it to determine whether
+        operator== can use memcmp.
+        
+        * wtf/Vector.h:
+        (WTF::):
+        (WTF::VectorTypeOperations::compare):
+        (WTF::operator==):
+        * wtf/VectorTraits.h:
+        (WTF::):
+
 2007-02-13  Brady Eidson  <beidson@apple.com>
 

trunk/JavaScriptCore/wtf/Vector.h

@@ -177 +177 @@
     };
     
+    template<bool canCompareWithMemcmp, typename T>
+    class VectorComparer;
+    
+    template<typename T>
+    struct VectorComparer<false, T>
+    {
+        static bool compare(const T* a, const T* b, size_t size)
+        {
+            for (size_t i = 0; i < size; ++i)
+                if (a[i] != b[i])
+                    return false;
+            return false;
+        }
+    };
+
+    template<typename T>
+    struct VectorComparer<true, T>
+    {
+        static bool compare(const T* a, const T* b, size_t size)
+        {
+            return memcmp(a, b, sizeof(T) * size) == 0;
+        }
+    };
+    
     template<typename T>
     struct VectorTypeOperations
@@ -208 +232 @@
         {
             VectorFiller<VectorTraits<T>::canFillWithMemset, T>::uninitializedFill(dst, dstEnd, val);
+        }
+        
+        static bool compare(const T* a, const T* b, size_t size)
+        {
+            return VectorComparer<VectorTraits<T>::canCompareWithMemcmp, T>::compare(a, b, size);
         }
     };
@@ -669 +698 @@
             return false;
 
-        for (size_t i = 0; i < a.size(); ++i)
-            if (a.at(i) != b.at(i))
-                return false;
-
-        return true;
+        return VectorTypeOperations<T>::compare(a.data(), b.data(), a.size());
     }
 

trunk/JavaScriptCore/wtf/VectorTraits.h

@@ -61 +61 @@
         static const bool canCopyWithMemcpy = false;
         static const bool canFillWithMemset = false;
+        static const bool canCompareWithMemcmp = false;
     };
 
@@ -72 +73 @@
         static const bool canCopyWithMemcpy = true;
         static const bool canFillWithMemset = sizeof(T) == sizeof(char);
+        static const bool canCompareWithMemcmp = true;
     };
 
@@ -85 +87 @@
         static const bool canCopyWithMemcpy = false;
         static const bool canFillWithMemset = false;
+        static const bool canCompareWithMemcmp = true;
     };
 
@@ -104 +107 @@
         static const bool canCopyWithMemcpy = FirstTraits::canCopyWithMemcpy && SecondTraits::canCopyWithMemcpy;
         static const bool canFillWithMemset = false;
+        static const bool canCompareWithMemcmp = FirstTraits::canCompareWithMemcmp && SecondTraits::canCompareWithMemcmp;
     };