On Friday, 1 August 2014 at 01:41:40 UTC, Daniel Gibson wrote:
Yep, also a good point.
(Actually it's 187 -f* options, the rest is -O* which can't be
combined of course and some of them most probably imply many of
the -f* switches, but it'll still be an unmanageable/untestable
amount of possible configurations)
Actually, it's much worse than that. ;) All of the -O switches
in GCC have a set of -f switches that they enable or disable.
What they DON'T tell you up front is that set of switches also
enables other optimisations. [0] I encountered a situation a
couple months ago where this actually mattered (i.e. runtime
segfault) for one particular C file if you built it with levels
above -O0, but enabling every single -f switch worked fine (still
not sure why; solved by switching to Clang and it compiles and
runs at all -O levels with no warnings).
-Wyatt
[0]
https://gcc.gnu.org/wiki/FAQ#Is_-O1_.28-O2.2C-O3_or_-Os.29_equivalent_to_individual_-foptimization_options.3F
