RFR: 8366702: C2 SuperWord: refactor VTransform vector nodes

[Emanuel Peter]

On Mon, 8 Sep 2025 06:13:21 GMT, Emanuel Peter <epeter at openjdk.org> wrote:

>> Yes, I was trying to get alignment. I'll try some alternatives.
>
> Variant 1: no alignment
> 
> ~  787   uint vlen = vector_length();
> ~  788   int vopc = _vector_opcode;
>    789   BasicType bt = element_basic_type();
>    790   const TypeVect* vt = TypeVect::make(bt, vlen);
> 
> It looks a bit noisy to me.
> 
> Variant 2: align on assignment operator
> 
> ~  787   uint vlen          = vector_length();                                                                                                                                                                                                                                                                                                                                                                                              
> ~  788   int vopc           = _vector_opcode;
> ~  789   BasicType bt       = element_basic_type();
>    790   const TypeVect* vt = TypeVect::make(bt, vlen);
> 
> Better. But somehow I'd still prefer if the names were also aligned. Question if left or right aligned looks better.
> 
> 3a
> 
> ~  787   uint            vlen = vector_length();                                                                                                                                                                                                                                                                                                                                                                                            
> ~  788   int             vopc = _vector_opcode;
> ~  789   BasicType       bt   = element_basic_type();
> ~  790   const TypeVect* vt   = TypeVect::make(bt, vlen);
> 
> 3b
> 
> ~  787   uint          vlen = vector_length();
> ~  788   int           vopc = _vector_opcode;
> ~  789   BasicType       bt = element_basic_type();                                                                                                                                                                                                                                                                                                                                                                                         
>    790   const TypeVect* vt = TypeVect::make(bt, vlen);
> 
> 
> Personally the last one looks the calmest to me. But it's a bit of a funky choice compared to the rest of hotspot, so it is probably just my own brain that thinks it is good.
> I think I'm going with variant 2, since that is a little less controversial I think, and still a bit better than no alignment at all.

I'm also refactoring away some of the assignments, and put the value directly at the use-site.

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PR Review Comment: https://git.openjdk.org/jdk/pull/27056#discussion_r2329242463