Title: [140186] trunk/Source
- Revision
- 140186
- Author
- msab...@apple.com
- Date
- 2013-01-18 11:16:26 -0800 (Fri, 18 Jan 2013)
Log Message
Refactor isPowerOf2() and add getLSBSet()
https://bugs.webkit.org/show_bug.cgi?id=107306
Reviewed by Filip Pizlo.
Source/_javascript_Core:
Moved implementation of isPowerOf2() to new hasOneBitSet() in wtf/MathExtras.h.
* runtime/PropertyMapHashTable.h:
(JSC::isPowerOf2):
Source/WTF:
Moved runtime/PropertyMapHashTable.h:PowerOf2() to new hasOneBitSet() and added getLSBSet().
* wtf/MathExtras.h:
(hasOneBitSet):
(getLSBSet):
Modified Paths
Diff
Modified: trunk/Source/_javascript_Core/ChangeLog (140185 => 140186)
--- trunk/Source/_javascript_Core/ChangeLog 2013-01-18 19:14:32 UTC (rev 140185)
+++ trunk/Source/_javascript_Core/ChangeLog 2013-01-18 19:16:26 UTC (rev 140186)
@@ -1,3 +1,15 @@
+2013-01-18 Michael Saboff <msab...@apple.com>
+
+ Refactor isPowerOf2() and add getLSBSet()
+ https://bugs.webkit.org/show_bug.cgi?id=107306
+
+ Reviewed by Filip Pizlo.
+
+ Moved implementation of isPowerOf2() to new hasOneBitSet() in wtf/MathExtras.h.
+
+ * runtime/PropertyMapHashTable.h:
+ (JSC::isPowerOf2):
+
2013-01-17 Mark Hahnenberg <mhahnenb...@apple.com>
Objective-C API: Clean up JSValue.mm
Modified: trunk/Source/_javascript_Core/runtime/PropertyMapHashTable.h (140185 => 140186)
--- trunk/Source/_javascript_Core/runtime/PropertyMapHashTable.h 2013-01-18 19:14:32 UTC (rev 140185)
+++ trunk/Source/_javascript_Core/runtime/PropertyMapHashTable.h 2013-01-18 19:16:26 UTC (rev 140186)
@@ -24,6 +24,7 @@
#include "PropertyOffset.h"
#include "WriteBarrier.h"
#include <wtf/HashTable.h>
+#include <wtf/MathExtras.h>
#include <wtf/PassOwnPtr.h>
#include <wtf/Vector.h>
#include <wtf/text/StringImpl.h>
@@ -50,9 +51,7 @@
inline bool isPowerOf2(unsigned v)
{
- // Taken from http://www.cs.utk.edu/~vose/c-stuff/bithacks.html
-
- return !(v & (v - 1)) && v;
+ return hasOneBitSet(v);
}
inline unsigned nextPowerOf2(unsigned v)
Modified: trunk/Source/WTF/ChangeLog (140185 => 140186)
--- trunk/Source/WTF/ChangeLog 2013-01-18 19:14:32 UTC (rev 140185)
+++ trunk/Source/WTF/ChangeLog 2013-01-18 19:16:26 UTC (rev 140186)
@@ -1,3 +1,16 @@
+2013-01-18 Michael Saboff <msab...@apple.com>
+
+ Refactor isPowerOf2() and add getLSBSet()
+ https://bugs.webkit.org/show_bug.cgi?id=107306
+
+ Reviewed by Filip Pizlo.
+
+ Moved runtime/PropertyMapHashTable.h:PowerOf2() to new hasOneBitSet() and added getLSBSet().
+
+ * wtf/MathExtras.h:
+ (hasOneBitSet):
+ (getLSBSet):
+
2013-01-18 David Kilzer <ddkil...@apple.com>
Fix WTF::copyLCharsFromUCharSource() to compile with -Wshorten-64-to-32
Modified: trunk/Source/WTF/wtf/MathExtras.h (140185 => 140186)
--- trunk/Source/WTF/wtf/MathExtras.h 2013-01-18 19:14:32 UTC (rev 140185)
+++ trunk/Source/WTF/wtf/MathExtras.h 2013-01-18 19:16:26 UTC (rev 140186)
@@ -294,6 +294,11 @@
return x > static_cast<float>(std::numeric_limits<int>::min()) && x < static_cast<float>(std::numeric_limits<int>::max());
}
+template<typename T> inline bool hasOneBitSet(T value)
+{
+ return !((value - 1) & value) && value;
+}
+
template<typename T> inline bool hasZeroOrOneBitsSet(T value)
{
return !((value - 1) & value);
@@ -304,6 +309,16 @@
return !hasZeroOrOneBitsSet(value);
}
+template <typename T> inline unsigned getLSBSet(T value)
+{
+ unsigned result = 0;
+
+ while (value >>= 1)
+ ++result;
+
+ return result;
+}
+
template<typename T> inline T timesThreePlusOneDividedByTwo(T value)
{
// Mathematically equivalent to:
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