Re: [PATCH v4 4/7] perf diff: Use hists to manage basic blocks per symbol

[Jin, Yao]

On 6/24/2019 3:57 PM, Jiri Olsa wrote:
> On Thu, Jun 20, 2019 at 10:36:39PM +0800, Jin Yao wrote:
>
> SNIP
>
> > +
> > +static void *block_entry_zalloc(size_t size)
> > +{
> > +	return zalloc(size + sizeof(struct hist_entry));
> > +}
> > +
> > +static void block_entry_free(void *he)
> > +{
> > +	struct block_info *bi = ((struct hist_entry *)he)->block_info;
> > +
> > +	block_info__put(bi);
> > +	free(he);
> > +}
> > +
> > +struct hist_entry_ops block_entry_ops = {
> > +	.new    = block_entry_zalloc,
> > +	.free   = block_entry_free,
> > +};
>
> hum, so there's already block_hist_ops moving that stuff into 'struct block_hist',
> which is great, but why don't we have 'struct block_entry' in here? that would
> keep the 'struct block_info'
>
> thanks,
> jirka

Hi Jiri,

If I define 'struct block_entry' as following and cast 'he' to 'struct 
block_entry' in some places, such as in block_cmp(), we can get the 
'struct block_entry'.

struct block_entry {
	struct block_info bi;
	struct hist_entry he;
};

But I don't know when I can set the 'bi' of 'struct block_entry'. Before 
or after calling hists__add_entry_xxx()? Before calling 
hists__add_entry_xxx(), we don't know the hist_entry. After calling 
hists__add_entry_xxx(), actually the hist_entry__cmp doesn't work (no bi ).

That's why I create block_info in hist_entry. Maybe I misunderstand what 
your suggested, correct me if I'm wrong.

Thanks
Jin Yao