[Bug c++/71618] Improve C++ compilation by adding specific optimization flags

[glisse at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71618

--- Comment #5 from Marc Glisse <glisse at gcc dot gnu.org> ---
We already have, just above the description of -O in the manual:

"      Not all optimizations are controlled directly by a flag.  Only
       optimizations that have a flag are listed in this section.

       Most optimizations are only enabled if an -O level is set on the
       command line.  Otherwise they are disabled, even if individual
       optimization flags are specified.

       Depending on the target and how GCC was configured, a slightly
       different set of optimizations may be enabled at each -O level than
       those listed here.  You can invoke GCC with -Q --help=optimizers to
       find out the exact set of optimizations that are enabled at each level."

Though I guess a bit of redundancy in the place you suggest may indeed help...