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Subject: Re: [PATCH] x86: bitops: fix build regression
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From:   "H. Peter Anvin" <hpa@zytor.com>
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Date:   Fri, 8 May 2020 10:31:36 -0700
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On 2020-05-08 10:21, Nick Desaulniers wrote:
>>
>> One last suggestion.  Add the "b" modifier to the mask operand: "orb
>> %b1, %0".  That forces the compiler to use the 8-bit register name
>> instead of trying to deduce the width from the input.
> 
> Ah right: https://gcc.gnu.org/onlinedocs/gcc/Extended-Asm.html#x86Operandmodifiers
> 
> Looks like that works for both compilers.  In that case, we can likely
> drop the `& 0xff`, too.  Let me play with that, then I'll hopefully
> send a v3 today.
> 

Good idea. I requested a while ago that they document these modifiers; they
chose not to document them all which in some ways is good; it shows what they
are willing to commit to indefinitely.

	-hpa