Re: [tip:core/types] bitops: Add sign_extend8(), 16 and 64 functions

[H. Peter Anvin]

On 02/04/2015 11:17 PM, Ingo Molnar wrote:
> > > Even for the 8bit ones? Since we have the *H and *L register
> > > we have more 8 bit regs than we have 16/32 bit regs and it
> > > might just be worth it.
> >
> > Fewer, actually.  gcc doesn't really use the H registers much,
>
> Is that true for other compilers as well?

Probably.  It wrecks havoc on register allocation, and it doesn't buy 
that much, especially on 64 bits where all the registers can be used for 
8-bit operations.

	-hpa

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