Re: [Minios-devel] [UNIKRAFT PATCH] lib/alloc: check for missing palloc implementation

[Hugo Lefeuvre <hugo.lefeuvre@xxxxxxxxx>]

Hi Simon,

On Wed, 2020-01-08 at 13:40 +0100, Simon Kuenzer wrote:
> <snip>
> >   static inline void *uk_palloc(struct uk_alloc *a, size_t order)
> >   {
> > -   if (unlikely(!a))
> > +   if (unlikely(!a) || unlikely(!a->palloc))
> Interesting... I am actually curious what the compiler does with
> your 
> condition. I would have written it with just one encapsulating 
> `unlikely` hint:
> 
> if (unlikely(!a || !a->palloc))
> 
> Maybe there is no difference and it turns out to be different coding 
> style. In general, having just one encapsulating hint maybe easier to
> read.
> 
> What do you think?

 unlikely(!a) || unlikely(!a->palloc)

and

 unlikely(!a || !a->palloc)

seem to result in the same binary, but the difference is unclear to me.
Anyways, let's opt for `unlikely(!a || !a->palloc)`, it looks better.

thanks!

cheers,
Hugo

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