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Re: list of optimizations done by -O1 level
- From: Ian Lance Taylor <iant at google dot com>
- To: ranjith kumar <ranjit_kumar_b4u at yahoo dot co dot uk>
- Cc: gcc-help at gcc dot gnu dot org
- Date: 22 Feb 2007 08:48:55 -0800
- Subject: Re: list of optimizations done by -O1 level
- References: <20070222163348.69871.qmail@web27407.mail.ukl.yahoo.com>
ranjith kumar <ranjit_kumar_b4u@yahoo.co.uk> writes:
> GCC manuals says the foloowing are the list of
> optimizations turned on when -O1 flag is used.
> -------------------------------------------------------
> -fdefer-pop -fdelayed-branch
> -fguess-branch-probability -fcprop-registers
> -floop-optimize -fif-conversion
> -fif-conversion2 -ftree-ccp -ftree-dce
> -ftree-dominator-opts -ftree-dse
> -ftree-ter -ftree-lrs -ftree-sra
> -ftree-copyrename -ftree-fre -ftree-ch
> -fmerge-constants
> -O also turns on -fomit-frame-pointer on
> machines where doing so does not
> interfere with debugging.
>
> -O doesnÂt turn on -ftree-sra for the Ada
> compiler. This option must be
> explicitly specified on the command line to
> be enabled for the Ada compiler.
> ----------------------------------------------------
The gcc manual also says:
Not all optimizations are controlled directly by a flag. Only
optimizations that have a flag are listed.
Ian