On 2/25/20 10:20 AM, Jakub Jelinek wrote:
> Hi!
>
> In Fedora we configure GCC with --with-arch=zEC12 --with-tune=z13 right now
> and furthermore redhat-rpm-config adds to rpm packages -march=zEC12 -mtune=z13
> options (among others). While looking at the git compilation, I've been
> surprised that -O2 actually behaves differently from -O2 -mtune=z13 in this
> configuration, and indeed, seems --with-tune= is completely ignored on s390
> if --with-arch= is specified.
>
> i386 had the same problem, but got that fixed in 2006, see PR26877.
> The thing is that for tune, we add -mtune=%(VALUE) only if neither -mtune=
> nor -march= is present, but as arch is processed first, it adds
> -march=%(VALUE) first and then -march= is always present and so -mtune= is
> never added.
> By reordering it in OPTION_DEFAULT_SPECS, we process tune first, add the
> default -mtune=%(VALUE) if -mtune= or -march= isn't seen, and then
> add -march=%(VALUE) if -march= isn't seen. It is true that cc1 etc.
> will be then invoked with -mtune=z13 -march=zEC12, but like if the user
> specifies it in that order, it should still use z13 tuning and zEC12
> ISA set.
>
> Bootstrapped/regtested on s390x-linux, ok for trunk?
>
> 2020-02-25 Jakub Jelinek <ja...@redhat.com>
>
> PR target/26877
> * config/s390/s390.h (OPTION_DEFAULT_SPECS): Reorder.
Ok. Thanks for fixing this.
Andreas
>
> --- gcc/config/s390/s390.h.jj 2020-01-12 11:54:36.412413424 +0100
> +++ gcc/config/s390/s390.h 2020-02-24 19:04:14.104259482 +0100
> @@ -227,11 +227,13 @@ enum processor_flags
> #define TARGET_DEFAULT 0
> #endif
>
> -/* Support for configure-time defaults. */
> +/* Support for configure-time defaults.
> + The order here is important so that -march doesn't squash the
> + tune values. */
> #define OPTION_DEFAULT_SPECS \
> { "mode", "%{!mesa:%{!mzarch:-m%(VALUE)}}" }, \
> - { "arch", "%{!march=*:-march=%(VALUE)}" }, \
> - { "tune", "%{!mtune=*:%{!march=*:-mtune=%(VALUE)}}" }
> + { "tune", "%{!mtune=*:%{!march=*:-mtune=%(VALUE)}}" }, \
> + { "arch", "%{!march=*:-march=%(VALUE)}" }
>
> #ifdef __s390__
> extern const char *s390_host_detect_local_cpu (int argc, const char **argv);
>
> Jakub
>
