[PATCH] rs6000: Make some BIFs vectorized on P10

Segher Boessenkool segher@kernel.crashing.org
Thu Aug 12 15:51:11 GMT 2021


On Thu, Aug 12, 2021 at 10:10:10AM +0800, Kewen.Lin wrote:
> > +      enum rs6000_builtins vname = RS6000_BUILTIN_COUNT;
> > 
> > Using this as a flag value looks unnecessary.  Is this just being done to silence a warning?
> 
> Good question!  I didn't notice there is a warning or not, just get used to initializing variable
> with one suitable value if possible.  If you don't mind, may I still keep it?  Since if some
> future codes use vname in a path where it's not assigned, one explicitly wrong enum (bif) seems
> better than a random one.  Or will this mentioned possibility definitely never happen since the
> current uninitialized variables detection and warning scheme is robust and should not worry about
> that completely?

It is a bad idea to initialise things unnecessary: it hinders many
optimisations, but much more importantly, it silences warnings without
fixing the problem.

> > +      if (vname != RS6000_BUILTIN_COUNT
> > 
> > Check is not necessary, as you will have returned by now in that case.
> 
> Thanks for catching, I put break for "default" initially, didn't noticed the following condition
> need an adjustment after updating it to early return.  Will fix it.

Thanks :-)


Segher


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