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Re: [PATCH] powerpc: New feature - HWCAP/HWCAP2 bits in the TCB
- From: Segher Boessenkool <segher at kernel dot crashing dot org>
- To: Kalle Olavi Niemitalo <kon at iki dot fi>
- Cc: libc-alpha <libc-alpha at sourceware dot org>
- Date: Thu, 9 Jul 2015 21:43:38 -0500
- Subject: Re: [PATCH] powerpc: New feature - HWCAP/HWCAP2 bits in the TCB
- Authentication-results: sourceware.org; auth=none
- References: <55760314 dot 6070601 at linux dot vnet dot ibm dot com> <559617FF dot 8010100 at redhat dot com> <20150703085542 dot GE32307 at domone> <55968AF8 dot 8060104 at redhat dot com> <20150703171121 dot GA23898 at domone> <1436283324 dot 12188 dot 25 dot camel at oc7878010663> <87egkhhtep dot fsf at Niukka dot kon dot iki dot fi>
On Fri, Jul 10, 2015 at 01:12:46AM +0300, Kalle Olavi Niemitalo wrote:
> Steven Munroe <firstname.lastname@example.org> writes:
> > if (__builtin_cpu_supports(ARCH_2_07) &&
> > __builtin_cpu_supports(VEC_CRYPTO))
> > This is 3 instructions (lwz, andi., bc) as packed bits, but 5 or 6 as
> > byte Boolean.
> I would understand 3 instructions for "||" (test the zero flag) but
> how do you do it for "&&"? I have hardly any powerpc experience
> though, so perhaps there is some trick I don't realize.
There is no such trick, you're not missing anything. And there is no
need to write error-prone manually expanded things, GCC can handle it
just fine (the simpler cases, anyway ;-) )