[webkit-dev] command line JSC vs. JSC in libQtWebKit

Osztrogonac Csaba oszi at inf.u-szeged.hu
Wed Feb 25 03:55:38 PST 2009

Hi all,

We are working on speedup jsc, and found a strange thing. Command
line JSC and JSC in libQtWebkit build with different gcc options:
- jsc.pro build command line jsc with: -O3
- WebCore.pro build libQtWebKit with: -O2 -fPIC -fno-strict-aliasing
(The latter is slower by 12%.)

If you implement an optimization, you measure speedup with command
line jsc on SunSpider. The results can be different if you measure
with a web browser such as QtLauncher. User usually not run command
line jsc, but a browser. Accordingly I suggest we should measure
performance users' point of view. Is neccesary building faster, but
different jsc? If no, possible solution can be: Build JavaScriptCore
library with JavaScriptCore.pro and link it with jsc command line
interface (jsc.o). Or make possibility in build system to build two
different jsc. One of them is faster for using in real life. The other
is slower, but same as running in browsers for testing and performance

Csaba Osztrogonac

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