Hello.
First, note that -O is equal to -O1 :) I noticed we don't use it consistently
in documentation:
$ git grep 'at.*-O1}' | cat
gcc/ada/gnat_ugn.texi:pick it based on the optimization level: 1 for
@code{-O1}, @code{-O2} or
gcc/ada/gnat_ugn.texi:The optimization level is at least @code{-O1}.
gcc/ada/gnat_ugn.texi:The optimization level is at least @code{-O1}.
gcc/doc/invoke.texi:Enabled at levels @option{-O1}, @option{-O2}, @option{-O3}
and @option{-Os},
gcc/doc/invoke.texi:The default is @option{-fbranch-count-reg} at @option{-O1}
and higher,
gcc/doc/invoke.texi:Enabled by default at @option{-O1} and higher.
gcc/doc/invoke.texi:at @option{-O1} and higher, except for @option{-Og}.
gcc/doc/invoke.texi:code. This pass is enabled by default at @option{-O1} and
higher,
gcc/doc/invoke.texi:enabled by default at @option{-O1} and higher, except for
@option{-Og}.
gcc/doc/invoke.texi:early. This flag is enabled by default at @option{-O1} and
higher,
gcc/doc/invoke.texi:@option{-ftoplevel-reorder} is the default at @option{-O1}
and higher, and
gcc/doc/invoke.texi:at level @option{-O1} and higher, except for @option{-Og}.
$ git grep 'at.*-O}' | cat
gcc/ada/gnat_ugn.texi:No optimization, the default setting if no @code{-O}
appears
gcc/ada/gnat_ugn.texi:Normal optimization, the default if you specify @code{-O}
without an
gcc/config/pa/pa-hpux.h: "%{!mpa-risc-1-0:%{!march=1.0:%{static:-L/lib/pa1.1
-L/usr/lib/pa1.1 }}}%{mlinker-opt:-O} %{!shared:-u main} %{static:-a archive} %{g*:-a
archive} %{shared:-b}"
gcc/config/pa/pa64-hpux.h: %{mhp-ld:+Accept TypeMismatch -z}
%{mlinker-opt:-O}\
gcc/config/pa/pa64-hpux.h: %{!mgnu-ld:+Accept TypeMismatch -z}
%{mlinker-opt:-O}\
gcc/doc/invoke.texi:compiling with optimization (@option{-Os}, @option{-O},
@option{-O2},
gcc/doc/invoke.texi:set of optimizations may be enabled at each @option{-O}
level than
gcc/doc/invoke.texi:@option{-O2} turns on all optimization flags specified by
@option{-O}. It
gcc/doc/invoke.texi:activated by @option{-O} options or are related to ones
that are. You
gcc/doc/invoke.texi:This option is enabled by default at optimization levels
@option{-O},
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}.
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
gcc/doc/invoke.texi:instructions to support this. Enabled by default at
@option{-O} and
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}, but
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}, but
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os},
gcc/doc/invoke.texi:at @option{-O} and higher.
gcc/doc/invoke.texi:at @option{-O} and higher.
gcc/doc/invoke.texi:This flag is enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:pass is enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:copy operations. This flag is enabled by default at
@option{-O} and
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:at @option{-O} and higher.
gcc/doc/invoke.texi:enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:default at @option{-O} and higher.
gcc/doc/invoke.texi:enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:flag is enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:is enabled by default at @option{-O} and higher. It is not
enabled
gcc/doc/invoke.texi:at @option{-O} and higher.
gcc/doc/invoke.texi:Enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:enabled by default at @option{-O} and higher.
gcc/doc/invoke.texi:calculations when possible. This is enabled by default at
@option{-O} and
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}.
gcc/doc/invoke.texi:The default is @samp{simple} at levels @option{-O},
@option{-Os}, and
gcc/doc/invoke.texi:If you do not specify an optimization level option
@option{-O} at
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}.
gcc/doc/invoke.texi:Enabled at levels @option{-O}, @option{-O2}, @option{-O3},
@option{-Os}.
Is the later (and more common variant) preferred?
Thanks,
Martin
