[PING] [PATCH] gdb: initialize the data_head variable to eliminate compilation warnings

[Enze Li]

Hi Markus,

Thanks for your review.

On Wed, 2022-07-06 at 14:02 +0000, Metzger, Markus T wrote:
> Hello Enze,
> 
> > > On a machine with gcc 12, I get this warning:
> > > 
> > >   CXX    nat/linux-btrace.o
> > > In function ‘btrace_error linux_read_bts(btrace_data_bts*,
> > > btrace_target_info*, btrace_read_type)’,
> > >     inlined from ‘btrace_error linux_read_btrace(btrace_data*,
> > > btrace_target_info*, btrace_read_type)’ at ../gdb/nat/linux-
> > > btrace.c:935:29:
> > > ../gdb/nat/linux-btrace.c:865:21: warning: ‘data_head’ may be
> > > used
> > > uninitialized [-Wmaybe-uninitialized]
> > >   865 |   pevent->last_head = data_head;
> > >       |   ~~~~~~~~~~~~~~~~~~^~~~~~~~~~~
> 
> That's a false positive.  Since RETRIES > 0, the loop is executed at
> least
> once and DATA_HEAD is initialized.

Yeah, that's my understanding as well.

> 
> 
> > > diff --git a/gdb/nat/linux-btrace.c b/gdb/nat/linux-btrace.c
> > > index b0d6dcd7cf1..c31fb5ffe43 100644
> > > --- a/gdb/nat/linux-btrace.c
> > > +++ b/gdb/nat/linux-btrace.c
> > > @@ -789,7 +789,7 @@ linux_read_bts (struct btrace_data_bts
> > > *btrace,
> > >    struct perf_event_buffer *pevent;
> > >    const uint8_t *begin, *end, *start;
> > >    size_t buffer_size, size;
> > > -  __u64 data_head, data_tail;
> > > +  __u64 data_head = 0, data_tail;
> > >    unsigned int retries = 5;
> > > 
> > >    pevent = &tinfo->variant.bts.bts;
> 
> OK to pacify GCC.  Thanks for the patch.  LGTM.

I'm checking this in now.

Thanks,
Enze

> 
> regards,
> markus.
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