On Thu, 5 Nov 2015, Joseph Myers wrote: > On Wed, 4 Nov 2015, Martin Sebor wrote: > > > Improving the compiler output is a good idea. The attached patch > > prints "[disabled by -O0]" instead of "[enabled]" when an optimization > > option is enabled by default but when optimization (i.e., -O1 or > > greater) is not enabled. > > I don't think it's entirely accurate that all options marked as > Optimization in *.opt are actually disabled by -O0. Many are, but it > depends on the actual logic controlling each optimization.
Indeed, and Richard already pointed that out when reviewing (my) previous attempt. Martin, please review the thread ending at https://gcc.gnu.org/ml/gcc-patches/2012-05/msg00113.html I guess eventually we can slightly overhaul optimization options to remove such ambiguities, but in short term I see no way to accurately determine whether a pass/option is ultimately in effect or not. Martin, what about taking Richard's suggestion, tacking a short explanatory sentence onto the end of --help=optimizers output? Thanks. Alexander
