[openssl-dev] Usage of assembler code on ARM architectures

[John Foley]

I can't speak directly to your question on the iphone-cross target, but
can warn you that your mileage will vary when using the ARM assembly
modules.  We observed that some algorithms actually run slower when
using the ARM assembly modules.  It's been a couple of years and I don't
recall the details, but want to say some of the hash algorithms were
actually faster when using no-asm.  The results are likely to vary
depending on the actual chipset used.  You'll probably want to test the
performance on the target hardware using the "openssl speed" command. 
You can do this on a jailbroken iOS device via SSH.



On 03/12/2015 11:17 AM, Stefan.Neis at t-online.de wrote:
>                Hi,
>
> While looking at the Configure script, I found that there is the armv4_asm variable, which seems to promise a speedup for ARM architectures (and the "4" in ARMv4 sounds like it should work "everywhere"?).
> However, further looking at that Configure file, I see it's only used for "linux-armv4" and "android-armv7", but not for e.g. iphoneos-cross. 
> Does that imply you know/suspect it doesn't work anyway? Or does it imply there is no measurable speedup? Or does it just imply you never bothered to actually test it? And in the last case, would you expect it's going to work (or "almost") or would you rather expect it's going to be lots of trouble?
> Similar question for Android: You only use the assembler code for the "android-armv7" configuration. For maximum compatibility, I'm usually compiling with "-march=armv5te", which still sounds like using "armv4" assembler should be safe, but for some reason, you're restricting its use to the "android-armv7" configuration which explicitly sets "-march=armv7-a". Why?
>
>           Regards,
>                        Stefan
>
>
> _______________________________________________
> openssl-dev mailing list
> To unsubscribe: https://mta.openssl.org/mailman/listinfo/openssl-dev
>