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[PATCH 1/9] x86: refine TPAUSE and UMWAIT

Jan Beulich jbeulich@suse.com
Wed Mar 4 11:40:00 GMT 2020 
On 04.03.2020 12:36, H.J. Lu wrote:
> On Wed, Mar 4, 2020 at 1:37 AM Jan Beulich <jbeulich@suse.com> wrote:
>>
>> Allowing 64-bit registers is misleading here: Elsewhere these get allowed
>> when there's no difference between either variant, because of 32-bit
>> destination registers having their upper halves zeroed in 64-bit mode.
>> Here, however, they're source registers, and hence specifying 64-bit
>> registers would lead to the ambiguity of whether the upper 32 bits
>> actually matter.
>>
>> Additionally, for proper code generation in 16-bit mode, IgnoreSize is
>> needed on both.
> 
> Are there testcases to show IgnoreSize is needed on them?

The situation with 16-bit test cases is rather poor anyway. I didn't
consider it reasonable to add such very special ones when far more
general ones don't exist. But if your question is to mean you demand
such to be added, then I'll (somewhat hesitantly) add/extend some.
Please clarify.

Jan
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