On Sun, Feb 14, 2010 at 11:12:23AM +0100, Peter Zijlstra wrote: > On Thu, 2010-02-11 at 18:24 +0100, Borislav Petkov wrote: > > On Mon, Feb 08, 2010 at 10:59:45AM +0100, Borislav Petkov wrote: > > > Let me prep another version when I get back on Wed. (currently > > > travelling) with all the stuff we discussed to see how it would turn. > > > > Ok, here's another version ontop of PeterZ's patch at > > http://lkml.org/lkml/2010/2/4/119. I need to handle 32- and 64-bit > > differently wrt to popcnt opcode so on 32-bit I do "popcnt %eax, %eax" > > while on 64-bit I do "popcnt %rdi, %rdi". > > Right, so I don't like how you need to touch !x86 for this, and I think > that is easily avoidable by not making x86 include > asm-generic/bitops/arch_hweight.h. > > If you then add __sw_hweightN() -> __arch_hweightN() wrappers in > arch_hweight.h, then you can leave const_hweight.h use __arch_hweightN() > and simply provide __arch_hweightN() from x86/include/asm/bitops.h Hmm, all these different names start to get a little confusing. Can we first agree on the naming please, here's my proposal: __const_hweightN - for at compile time known constants as arguments __arch_hweightN - arch possibly has an optimized hweight version __sw_hweightN - fall back when nothing else is there, aka the functions in lib/hweight.c Now, in the x86 case, when the compiler can't know that the argument is a constant, we call the __arch_hweightN versions. The alternative does call the __sw_hweightN version in case the CPU doesn't support popcnt. In this case, we need to build __sw_hweightN with -fcall-saved* for gcc to be able to take care of the regs clobbered ny __sw_hweightN. So, if I understand you correctly, your suggestion might work, we simply need to rename the lib/hweight.c versions to __sw_hweightN and have <asm-generic/bitops/arch_hweight.h> have __arch_hweightN -> __sw_hweightN wrappers in the default case, all arches which have an optimized version will provide it in their respective bitops header... Hows that? -- Regards/Gruss, Boris. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
