For Apple silicon, use machdep.cpu.brand_string in preference to decoding hw.machine

[dlenski]

This functionality was implemented in #65 ("Updated package.name to also query machdep.cpu.brand_string if decode of hw.machine fails"), but then it was omitted from the subsequent #100, probably inadvertently.

Adding that functionality back here, so that the package/device name can be shown correctly on recent devices and macOS/iOS versions. I have reversed the order so that machdep.cpu.brand_string is checked before attempting to decode hw.machine, since the former appears to be more future-proof.

Before this change, on a recent MacBook Pro:

$ cpu-info
...
Debug (cpuinfo): hw.machine: arm64
Warning in cpuinfo: parsing "hw.machine" failed: Undefined error: 0
...
Packages:
    0:

After this change:

$ cpu-info
...
Debug (cpuinfo): machdep.cpu.brand_string: Apple M2 Pro
...
Packages:
    0: Apple M2 Pro

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[dlenski]

This PR does exactly what it says it does, but it has not received any review or comments for ~6 months.

I see that @gonnet has recently merged a PR for Apple/Mach (https://github.com/pytorch/cpuinfo/commit/973ec72753f8cfabcd50db5a881ea06b92498ae0). Perhaps he could review this one as well? 😃

[dlenski]

I fixed the clang-format violation from d8d9389 in 04efc5e (diff):

diff --git a/src/arm/mach/init.c b/src/arm/mach/init.c
index b37b6bb..c4e6521 100644
--- a/src/arm/mach/init.c
+++ b/src/arm/mach/init.c
@@ -109,7 +109,7 @@ static int read_package_name_from_brand_string(char* package_name) {
                return false;
        }

-       char *brand_string = alloca(size);
+       char* brand_string = alloca(size);
        if (sysctlbyname("machdep.cpu.brand_string", brand_string, &size, NULL, 0) != 0)
                goto sysctlfail;
        cpuinfo_log_debug("machdep.cpu.brand_string: %s", brand_string);

@malfet, @gonnet, could whoever trigger the PR workflows please retrigger it? 😅

[F0bes]

Hi there. I come from @PCSX2 and we depend on this library. In hopes that this gets some attention, and so we can avoid manually patching the dependency, I just wanted to say that I've applied this patch locally and it works as expected. I'm using an Apple Mac Mini M4 Pro. Thanks :)

[digantdesai]

Thanks. LGTM. Sorry for the delay.