Boost performance of QChar::isSpace

Make it inline; add fast checks for typical spaces;
add fallback function that uses the fastcall calling
convention.

On ia32, this change makes isSpace ~340x faster for
ascii spaces, ~170x faster for non-space ascii
characters, and ~1.3x faster for non-ascii characters.

Note that this change is NOT binary compatible.

Also add an autotest with expected results from
before the optimization, to ensure that the behavior
is the same.

Change-Id: I9438d0ad3c9ba2e80560c4bee7eed05115265798
Reviewed-on: http://codereview.qt-project.org/4905
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/src/corelib/tools/qchar.h b/src/corelib/tools/qchar.h
index 36e185ebce..b82addb4c5 100644
--- a/src/corelib/tools/qchar.h
+++ b/src/corelib/tools/qchar.h
@@ -232,7 +232,10 @@ public:
     inline bool isNull() const { return ucs == 0; }
     bool isPrint() const;
     bool isPunct() const;
-    bool isSpace() const;
+    inline bool isSpace() const {
+        return ucs == 0x20 || (ucs <= 0x0D && ucs >= 0x09)
+                || (ucs > 127 && isSpace(ucs));
+    }
     bool isMark() const;
     inline bool isLetter() const {
         return (ucs >= 'a' && ucs <= 'z')
@@ -329,6 +332,7 @@ private:
     static bool QT_FASTCALL isDigit(ushort ucs2);
     static bool QT_FASTCALL isLetter(ushort ucs2);
     static bool QT_FASTCALL isLetterOrNumber(ushort ucs2);
+    static bool QT_FASTCALL isSpace(ushort ucs2);
 
 #ifdef QT_NO_CAST_FROM_ASCII
     QChar(char c);