RE: [PATCH v2 1/8] minmax: Put all the clamp() definitions together

David Laight
2024-07-28T18:12:14Z

From: Linus Torvalds
> Sent: 28 July 2024 18:25
>
> On Sun, 28 Jul 2024 at 07:18, David Laight <David.Laight@aculab.com> wrote:
> >
> > +#define min_t(type, x, y) __careful_cmp(min, (type)(x), (type)(y))
> > +#define max_t(type, x, y) __careful_cmp(max, (type)(x), (type)(y))
>
> This is unrelated to your patch, but since it moves things around and
> touches these, I reacted to it..
>
> We should *not* use __careful_cmp() here.
>
> Why? Because part of __careful_cmp() is the "only use arguments once".
>
> But *another* part of __careful_cmp() is "be careful about the types"
> in __cmp_once().
>
> And being careful about the types is what causes horrendous expansion,
> and is pointless when we just forced things to be the same type.
>
> So we should split __careful_cmp() into one that does just the "do
> once" and one that then also does the type checking.
...

Yes I've seen that and left well alone :-)
Or rather, left it until after MIN() and MAX() are used for constants.

Although min_t(type,x,y) should just be
type __x = x;
type __y = y;
__x < __y ? __x : __y;
Absolutely no point doing anything else.

David

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