Re: [Qemu-devel] [RISU v2 07/11] test_i386: change syntax from nasm to gas

[Jan Bobek]

On 5/21/19 11:30 AM, Alex Bennée wrote:
> 
> Richard Henderson <address@hidden> writes:
> 
>> On 5/21/19 5:08 AM, Alex Bennée wrote:
>>>>> We probably need to zero or reset the xmm regs both in the test and when
>>>>> risugen dumps it's preamble.
>>>>>
>>>>
>>>> That gets fixed later in the series.
>>>
>>> So it does, but I'm still seeing the test fail when played back :-/
>>
>> Um, no, I mean this test is extended in patch 9, exactly how you suggest.  
>> Are
>> you trying to run the test as seen in patch 7 against the final
>> series?
> 
> Running against:
> 
>   commit 555748b35849ad4d354a9a3cd7f8549994b2bea4 (HEAD -> 
> review/i386-support-v2)
>   Author: Jan Bobek <address@hidden>
>   Date:   Fri May 17 18:44:50 2019 -0400
> 
>       risu_reginfo_i386: accept named feature sets for --xfeature
> 
> fails for me.

I get the same behavior, but it only occurs on 32bit builds of
RISU. Specifically, in risu_reginfo_i386.c, lines 172--178:

    for (i = 0; i < nvecregs; ++i) {
#ifdef __x86_64__
        memcpy(&ri->vregs[i], &fp->xmm_space[i], 16);
#else
        memcpy(&ri->vregs[i], &fp->_xmm[i * 4], 16);
#endif
    }

In the #else branch, fp->_xmm has type _libc_xmmreg[16], and
_libc_xmmreg itself is a struct with a 4-element array of uint32s. On
my box, this gets fixed by dropping the multiplication from the index,
i.e.

        memcpy(&ri->vregs[i], &fp->_xmm[i], 16);

I wonder why Richard wrote it like this in the first place; did
fp->_xmm use to be an array of uint32s in previous versions of this
API?

-Jan

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