[PATCH/AARCH64] Improved -mcpu/mtune/march=native handling

[Richard Earnshaw]

On 11/11/16 02:56, Andrew Pinski wrote:
> As I mentioned in my other emails, parsing /proc/cpuinfo has one issue
> is that the current parsing assumes many different things about the
> format.  So the best way to do this is to parse
> /sys/devices/system/cpu/cpuN/regs/identification/midr_el1 files
> instead.  To get which cpu are present (though not necessarily online)
> we parse "/sys/devices/system/cpu/present" file.  We fall back to
> parsing /proc/cpu if any parsing fails of these files including not
> finding out which cpu we are on.  The main reason why we fall back is
> because only newer kernels support exporting this file.  To get the
> features I just look at the hwcap that the kernel passes to userspace
> so I needed to add an extra argument to AARCH64_OPT_EXTENSION.  I also
> had to define some HWCAP_* macros in driver-aarch64.c since older
> kernels headers don't have these values defined.
> 
> It should also be possible to parse
> /sys/devices/system/cpu/cpu%d/cache%d directory to get cache
> information too but that is left for another patch and another time.
> 
> Since I don't have access to a big.LITTLE system, someone should test
> there with a new enough kernel; I was using stock 4.9.0-rc3.
> 
> OK?  Bootstrapped and tested on ThunderX on aarch64-linux-gnu with no
> regressions and making sure /proc/cpuinfo is not read (by using
> strace).
> 
> Thanks,
> Andrew Pinski
> 
> ChangeLog:
> * config/aarch64/aarch64-option-extensions.def: Document extra
> argument to AARCH64_OPT_EXTENSION.  Update for the extra argument for
> all of the option extensions.
> * config/aarch64/driver-aarch64.c: Include sys/auxv.h and asm/hwcap.h.

GCC supports native builds on freebsd as well as linux.  Isn't this
going to break that?

R.

> (HWCAP_CRC32): Define if needed.
> (HWCAP_ATOMICS): Likewise.
> (HWCAP_FPHP): Likewise.
> (HWCAP_ASIMDHP): Likewise.
> (aarch64_arch_extension): New field hwcap_mask.
> (AARCH64_OPT_EXTENSION): Handle extra argument.
> (AARCH64_BIG_LITTLE): Always put the larger core number first.
> (valid_bL_core_p): Don't check AARCH64_BIG_LITTLE for the opposite
> order as it already handles the order.
> (implementor_from_midr): New function.
> (part_no_from_midr): New function.
> (sysfsformat): New define.
> (host_detect_local_cpu_sys): New function.
> (host_detect_local_cpu): Call host_detect_local_cpu_sys if opening
> "/sys/devices/system/cpu/present" file worked.
> * common/config/aarch64/aarch64-common.c (AARCH64_OPT_EXTENSION):
> Handle extra argument.
>