Re: changing "configure" to default to "gcc -g -O2 -fwrapv ..."

[Paul Eggert <eggert at CS dot UCLA dot EDU>]

Robert Dewar <dewar@adacore.com> writes:

> Of course there is a way out that satisfies both
> sides here, and that is to declare that gcc code
> should adhere to the standard *including* LIA
> and then make sure the default mode of gcc is
> LIA compliant.

Yes, this should solve the problem.  The idea is that -O2
would assume wrapv semantics.  It's fine with me if higher
optimization levels disable -fwrapv by default.

As I understand it the principal argument against this
change is that the performance of some numeric programs
would be adversely affected.  But like you, I doubt whether
it'd affect GCC's performance much, nor would it much affect
the performance of glibc, coreutils, etc., etc.

Also, as I understand it this change shouldn't affect gcc's
SPEC benchmark scores, since they're typically done with -O3
or better.