All CLA requirements met.

I'd like to encourage this to be merged: it fixed the armel build of SolveSpace on Debian, and we'd like to just update to a new upstream version rather than carrying this patch ourselves.

Interesting. Is there any benchmark for the arm64 case (cpu usage, performance)?

Interesting. Is there any benchmark for the arm64 case (cpu usage, performance)?

I don't have benchmarks, but the wfe instruction is how the Linux kernel does atomic yields for their spinlocks (arch_spin_lock) on arm64, arm 32v7, and arm 32v6 with k extension

https://sources.debian.org/src/linux/5.10.9-1/arch/arm/include/asm/spinlock.h/?hl=36#L74

the arm64 definition of the wfe alias is https://sources.debian.org/src/linux/5.10.9-1/arch/arm64/include/asm/barrier.h/?hl=18#L18

#define wfe() asm volatile("wfe" : : : "memory")

and the arm (32-bits) definition of the wfe alias is https://sources.debian.org/src/linux/5.10.9-1/arch/arm/include/asm/barrier.h/?hl=18#L12

#define wfe() __asm__ __volatile__ ("wfe" : : : "memory")

true even tough bit_spin_lock, thus cpu_relax use yield on arm64 thus why I was curious about benefits (outcome might differ b/w mono vs multi thread context as well).

Note : I genuinely hope your suggestions are beneficial, it is just to have some background.

If nothing else, the commit distinguishing versions of ARM in the dev branch were needed to fix armel builds in Debian. Is there a timeline for an upcoming release from dev?

There is one ( too many in this PR

I think:

(defined(__x86_64__) || defined(__i386__) || (defined(__arm__) || defined(__armel__) || defined(__ARMEL__) || defined(__aarch64__) || defined(__powerpc__) || defined(__ppc__) || defined(__PPC__))

Was intended to be:

(defined(__x86_64__) || defined(__i386__) || defined(__arm__) || defined(__armel__) || defined(__ARMEL__) || defined(__aarch64__) || defined(__powerpc__) || defined(__ppc__) || defined(__PPC__))

Diff for clarity:

- (defined(__x86_64__) || defined(__i386__) || (defined(__arm__) || defined(__armel__) || defined(__ARMEL__) || defined(__aarch64__) || defined(__powerpc__) || defined(__ppc__) || defined(__PPC__))
+ (defined(__x86_64__) || defined(__i386__) || defined(__arm__) || defined(__armel__) || defined(__ARMEL__) || defined(__aarch64__) || defined(__powerpc__) || defined(__ppc__) || defined(__PPC__))

@rpavlik: I will merge this now into dev (and fix the extra parenthesis @vespakoen -- thanks!). The plan is to release soon a new version based on dev, and then soon after a new version based on dev-slice. I hope to release a new master with a week depending on how things go.

great, thanks!

Thanks, all!