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Re: optimization issue about -O2 and -Os


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
http://gcc.gnu.org/bugs.html
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



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