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List:       qemu-ppc
Subject:    Re: target/ppc: Move VMX int add/sub saturate insns to decodetree.
From:       Chinmay Rath <rathc () linux ! vnet ! ibm ! com>
Date:       2024-05-16 16:31:05
Message-ID: 77730b44-4291-4199-8cde-8edd57b7795b () linux ! vnet ! ibm ! com
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Hi Richard,

On 5/12/24 15:59, Richard Henderson wrote:
> On 5/12/24 11:38, Chinmay Rath wrote:
>> 1. vsubsbs and bcdtrunc :
>>
>> In this pair, bcdtrunc has the insn flag check PPC2_ISA300 in the
>> vmx-impl file, within the GEN_VXFORM_DUAL macro, which does this flag
>> check.
>> However it also has this flag check in the vmx-ops file.
>> Hence I have retained the same in the new entry in the vmx-ops file.
>> This is consistent with the behaviour in done in the following commit :
>> https://github.com/qemu/qemu/commit/b132be53a4ba6a0a40d5643d791822f958a36e53 
>>
>> So even though the flag check is removed from the vmx-impl file, it is
>> retained in the vmx-ops file. All good here.
>>
>> 2. vadduhs and vmul10euq :
>>
>> In this pair, vmul10euq has the insn flag check PPC2_ISA300 in the
>> vmx-impl file, check done within the GEN_VXFORM_DUAL macro.
>> However the same flag was NOT originally present in the
>> vmx-ops file, so I have NOT included in its new entry in the vmx-ops
>> file. I have done this, following the behaviour done in the following
>> commit :
>> https://github.com/qemu/qemu/commit/c85929b2ddf6bbad737635c9b85213007ec043af 
>>
>> So this flag check for vmul10euq is excluded now. Is this not a 
>> problem ?
>> I feel that this leads to the flag check being skipped now, however this
>> behaviour was followed in the above mentioned commit.
>
> This second link is for VAVG* and VABSD*.
>
> Yes you are correct that this second case was done incorrectly. 
> Thankfully the mistake was fixed in the very next commit, when VABSD* 
> was converted to decodetree as well.
>
Thank you very much for the clarification !
>
> r~
Regards,
Chinmay

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