On 18/11/2020 17:16, Pop, Sebastian via Gcc-patches wrote: > Hi, > > On 11/18/20, 10:17 AM, "Wilco Dijkstra" <wilco.dijks...@arm.com> wrote: >> I presume you're trying to unify the --with- options across most targets? > > Yes, my intention was to provide the same configure options on arm64 > as on x86, such that projects that already use those options can change > cpu name to "neoverse-n1" and that will build a compiler with the right > tuning for Graviton2. > > Allowing arm64 users to specify all the flags available on x86 is important. > >> That would be very useful! However there are significant differences >> between >> targets in how they interpret options like --with-arch=native (or >> -march). So >> those differences also need to be looked at and fixed to avoid unexpected >> results. >> >> As for the first patch, I think support for --witch-tune requires more >> changes. >> Without proper processing of a --with-tune, you get an incorrect >> architecture >> version (if say the CPU you tune for is newer than the --with-cpu/arch >> or default). >> >> I posted patches to add --with-tune and fix various issues a while back: >> https://gcc.gnu.org/pipermail/gcc-patches/2020-September/553865.html >> https://gcc.gnu.org/pipermail/gcc-patches/2020-September/553866.html > > Thanks for pointing me to your patches, I was not aware of these changes. > I see that your patches enable more use cases and fix several bugs. > These changes would definitely be good to have in trunk and branches. > > My patch was the minimal change to enable --with-tune=neoverse-n1 > >> As for your second patch, --with-cpu-64 could be a simple alias indeed, >> but what is the exact definition/expected behaviour of a --with-cpu-32 >> on a target that only supports 64-bit code? The AArch64 target cannot >> generate AArch32 code, so we shouldn't silently accept it. > > IMO allowing users to specify all the flags available on x86 is important. >
This isn't about general users though; it's about how you configure the compiler and that's not all the same. I don't mind the --with-cpu-64 as a strict alias for --with-cpu, but --with-cpu-32 is both redundant and misleading as it might give the impression that it does something useful. R. > Thanks, > Sebastian >
