RE: [PATCH v2, rs6000] Change insn condition from TARGET_64BIT to TARGET_POWERPC64 for VSX scalar extract/insert instructions

[HAO CHEN GUI <guihaoc@linux.ibm.com>]

On 7/9/2022 下午 10:25, Segher Boessenkool wrote:
> Hi!
> 
> On Wed, Sep 07, 2022 at 08:51:17AM -0500, Paul A. Clarke wrote:
>> On Tue, Sep 06, 2022 at 12:19:06PM -0500, Segher Boessenkool wrote:
>>> On Mon, Sep 05, 2022 at 02:36:30PM +0800, HAO CHEN GUI wrote:
>>>> The return type of vec_ version built-ins are different than their definition
>>>> in PVIPR. In PVIPR, they're vector unsigned int or vector unsigned long long.
>>>> Shall we correct them?
>>>>
>>>>   const vd __builtin_vsx_extract_exp_dp (vd);
>>>>     VEEDP xvxexpdp {}
>>>>
>>>>   const vf __builtin_vsx_extract_exp_sp (vf);
>>>>     VEESP xvxexpsp {}
>>>>
>>>>   const vd __builtin_vsx_extract_sig_dp (vd);
>>>>     VESDP xvxsigdp {}
>>>>
>>>>   const vf __builtin_vsx_extract_sig_sp (vf);
>>>>     VESSP xvxsigsp {}
>>>
>>> Those are the vsx_ versions.  I'm not sure what you're asking.
>>>
>>> It won't be easy at all to change types from vector integer to vector
>>> float, it will break all over.  A compatibility nightmare.  It is better
>>> if you can show the current stuff cannot ever work, it's not a problem
>>> to replace it in that case.
>>
>> I think Hao Chen is concerned about the return types:
> 
> Yes, and so am I.
> 
>>>>   const vd __builtin_vsx_extract_exp_dp (vd);
>>>>     VEEDP xvxexpdp {}
>>
>> Per PVIPR, this should return vector unsigned long long ("vull" not "vd").
> 
> But changing that will make any existing code that now works, fail
> horribly.  Of course it is possible no such code exists :-)
> 
> What did this do before the builtin rewrite?
> 
> 
>  ~ - ~ - ~
> 
> 
> It looks like it did the right thing before, but that is just based on
> reading the code, I haven't actually tried it :-)
> 
> So, changing the vsx_ code here should be okay, because obviously no one
> is using it.  OTOH, why do we have those separately at all, why do they
> not just redirect to the canonical vec_ versions?  Or, can we just get
> rid of the vsx_ version completely?

In rs6000-overload.def, the vsx_ version built-ins are overridden to vec_
version. And the return types of vec_ version is inline with those defined
in PVIPR. So there should be no problem. Sorry for that.

[VEC_VEEDP, vec_extract_exp_dp, __builtin_vec_extract_exp_dp]
  vull __builtin_vec_extract_exp_dp (vd);
    VEEDP  VEEDP_DEPR1

[VEC_VEESP, vec_extract_exp_sp, __builtin_vec_extract_exp_sp]
  vui __builtin_vec_extract_exp_sp (vf);
    VEESP  VEESP_DEPR1

[VEC_VEE, vec_extract_exp, __builtin_vec_extract_exp]
  vui __builtin_vec_extract_exp (vf);
    VEESP
  vull __builtin_vec_extract_exp (vd);
    VEEDP

Thanks
Gui Haochen