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Re: [PATCH] powerpc: New feature - HWCAP/HWCAP2 bits in the TCB


On Fri, Jul 10, 2015 at 01:12:46AM +0300, Kalle Olavi Niemitalo wrote:
> Steven Munroe <munroesj@linux.vnet.ibm.comcom> 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 ;-) )


Segher


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