On Wed, 20 Jan 2021 at 19:06, mark_at_yahoo <markrubn@xxxxxxxxx> wrote: > > On 1/20/21 10:50 AM, Jonathan Wakely wrote: > > > That's a different situation though. With -O0 **NO** optimization is done, > > at all. Any -f options for optimization passes are ignored entirely. > > > > The difference between -O1 and -O2 is the set of -f flags that differ, and > > some specific checks for >= -O2. But the difference between -O0 and -O1 is > > the difference between zero and non-zero. Completely off, or on. > > > > That's interesting, Jonathan. You know far better than I do, and I > haven't tried it in over a year (on an older version of GCC-ARM), but I > swore the following did do something: It might have done something, but it didn't optimize anything (and so most of those options were ignored). https://gcc.gnu.org/wiki/FAQ#optimization-options
