Re: [Qemu-devel] [PATCH v5 01/35] target/arm: Implement SVE Memory Contiguous Load Group

[Richard Henderson]

On 06/26/2018 02:55 AM, Alex Bennée wrote:
>> +/* Convert a 2-bit memory size (msz) to a 4-bit data type (dtype)
>> + * with unsigned data.  C.f. SVE Memory Contiguous Load Group.
>> + */
>> +static inline int msz_dtype(int msz)
>> +{
>> +    static const uint8_t dtype[4] = { 0, 5, 10, 15 };
>> +    return dtype[msz];
>> +}
> I'm a little confused by the magic numbers in dtype[4], do they map
> directly to dtype_mop[]?
> 

Well, yes, this would sort of be the inverse of dtype_mop.

My intent with the comment was to point you to the table within
the SVE Memory - Contiguous Load Group section of
the Index by Encoding page:

DDI0584A_d_SVE/SVE_xml/xhtml/encodingindex.html#sve_memcld

and that I'm picking out the unsigned loads of size 1, 2, 4, 8.

Do you have a suggested re-wording?

I should note that *most* load operations use a 4-bit dtype field, except for
the non-temporal loads, which use a 2-bit msz field.  Since qemu does not care
about the memory hierarchy, by mapping msz back into dtype I can forward the
implementation directly to the normal load routines.


r~