optimize QList::removeAll()

a) don't detach until an occurrence found
b) don't memmove every time an occurrence found
c) truncate quickly )

well, numbers are better than words:
before:
RESULT : tst_QList::removeAll_primitive():
     2,617,902 CPU ticks per iteration (total: 261,790,171, iterations: 100)
RESULT : tst_QList::removeAll_movable():
     2,547,540 CPU ticks per iteration (total: 254,753,960, iterations: 100)
RESULT : tst_QList::removeAll_complex():
     16,852,099 CPU ticks per iteration (total: 1,685,209,906, iterations: 100)

after:
RESULT : tst_QList::removeAll_primitive():
     73,520 CPU ticks per iteration (total: 73,520,442, iterations: 1000)
RESULT : tst_QList::removeAll_movable():
     90,422 CPU ticks per iteration (total: 90,422,464, iterations: 1000)
RESULT : tst_QList::removeAll_complex():
     9,667,073 CPU ticks per iteration (total: 9,667,072,670, iterations: 1000)

Merge-request: 1285
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

(cherry picked from commit b209fe3b1a51f64541067917e96de99f14ad65f3)

Change-Id: Ia26036ed741cefcf4b5868b7b2fc5eae8130d3dc
Reviewed-on: http://codereview.qt-project.org/4577
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/tests/benchmarks/corelib/tools/qlist/qlist.pro b/tests/benchmarks/corelib/tools/qlist/qlist.pro
new file mode 100644
index 0000000000..902e72eb2e
--- /dev/null
+++ b/tests/benchmarks/corelib/tools/qlist/qlist.pro
@@ -0,0 +1,5 @@
+load(qttest_p4)
+TARGET = tst_qlist
+QT = core
+
+SOURCES += main.cpp