port only builds with build_arch=i386 on command line -- any way to specify that in the portfile?

[Fred Wright]

On Mon, 5 Sep 2016, Brandon Allbery wrote:
> On Mon, Sep 5, 2016 at 8:10 PM, Fred Wright <fw at fwright.net> wrote:
>
> > But when they switched to Intel, they also switched
> > to -O2.  This allowed them to inflate the performance benefit of the
> > architecture switch. :-)
> >
>
> ...as long as -O2 worked. Experience from FreeBSD and from early MacPorts
> experiments with -O2 is that it took -O2 a long time to actually generate
> correct code in a majority of cases.
> That said, it might be worth looking at again --- but, -O2 reportedly still
> causes occasional problems for some programs, so be ready to bail back to
> -Os.

Interesting, given that the Linux kernel *requires* optimization to build
correctly, due to some issue with macros vs. inline functions.  Of course
that's gcc, not clang, and it doesn't necessarily rule out -Os.  It is
unfortunate for debugging, since, gdb's claims to be able to debug
optimized code notwithstanding, it's seriously deficient at it.

On Mon, 5 Sep 2016, Ken Cunningham wrote:

> This website reference says -Os and -O2 are identical:
>
> <http://stackoverflow.com/questions/15548023/clang-optimization-levels

That's not necessarily true of all compilers, though, so I'd use -Os where
size is important and -O2 (or greater) where speed is important.  I
suspect that the only reason -O2 and -Os are equivalent in clang is that
they decided that nobody cares about code size any more. :-)

BTW, the original poster on that page mistakenly thinks that the "s" is
for speed.

Fred Wright