Re: [tip:x86/asm] x86, bitops: Change bitops to be native operand size

Joe Perches
2013-11-11T02:23:15Z

On Sun, 2013-11-10 at 18:06 -0800, H. Peter Anvin wrote:
> On 11/10/2013 02:44 PM, Joe Perches wrote:
> > On Sun, 2013-11-10 at 14:10 -0800, H. Peter Anvin wrote:
> >> Yes, on the generic it is int.
> >> The problem is in part that some architectures have bitop
> >> instructions with specific behavior.
> > I think that all bitop indices should be changed
> > to unsigned (int or long, probably long) for all
> > arches.
> > Is there any impediment to that?
> It is at the very best misleading. On x86 bit indicies will be signed
> no matter what the data type says,

?

> and having an unsigned data type
> being interpreted as signed seems like really dangerous.
> On the other hand, for the generic implementation unsigned long makes sense.
> We might need a bitindex_t or something like that for it to be clean.

Is there really any reason to introduce bitindex_t?

Perhaps the current x86 bitops asm code is being conflated
with the ideal implementation?