Re: [PATCH v4 06/57] accel/tcg: Honor atomicity of loads

[Richard Henderson]

On 5/9/23 13:04, Peter Maydell wrote:
> > If the LDP is aligned mod 8, but not aligned mod 16, then both 8-byte 
> > operations must be
> > (separately) atomic, and we return MO_64.
>
> So there's an implicit "at most 2 atomic sub-operations
> inside a WITHIN16 load" restriction? i.e. you can't
> use WITHIN16 to say "do this 8 byte load atomically but
> if it's not in a 16-byte region do it with 4 2-byte loads",
> even though in theory MO_ATOM_WITHIN16 | MO_ATMAX_2 | MO_8
> would describe that ?

Correct on both counts.  While you're right that this is a valid generalization, it's not 
something for which I've found a use case.


r~