Make it inline; add fast checks for ascii letters;
add fallback function that uses the fastcall calling
convention.
On ia32, this change makes isLetter ~370x faster for
ascii letters, ~250x faster for non-letter ascii
characters, and ~1.5x 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: I06f8d3d43114537cee5567e670898cef6494c20a
Reviewed-on: http://codereview.qt-project.org/4903
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Lars Knoll <lars.knoll@nokia.com>
a48e9af146