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Re: optimization issue about -O2 and -Os
- From: Jim Wilson <wilson at specifixinc dot com>
- To: Ebony Zhu <ebony dot zhu at motorola dot com>
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 29 Apr 2004 15:58:28 -0700
- Subject: Re: optimization issue about -O2 and -Os
- References: <1083221404.1215.267.camel@Woogie>
Ebony Zhu wrote:
build some applications such as U-Boot, Busybox..., with the -Os
optimization, the apps can be built but cannot run (just halted, there
were even no error messages). If I use -O2 switch then everything is OK.
According to manpage of GCC, -Os is based on -O2 switch and does some
work to reduce the code size. What GCC did on earth with the -Os switch?
The -Os option is buggy. You might want to report a bug into our
bugzilla bug datase. See
for more info on reporting bugs.
Though the -Os option is based on the -O2 option, it is a different
option, that generates different code, and has different bugs.
Jim Wilson, GNU Tools Support, http://www.SpecifixInc.com