Re: [PATCH] gdb: CTF support

[Wei-min Pan <weimin dot pan at oracle dot com>]

On 7/25/2019 5:42 AM, Tom Tromey wrote:
>>>>> ">" == Wei-min Pan <weimin.pan@oracle.com> writes:

> Tom> dependencies = { module=all-binutils; on=all-libctf; };
>
> >> There are more libctf changes in both Makefile.def and Makefile.in.
> >> Please see commit 0e65dfbaf3a0299e4837216a103c28625d4b4f1d which
> >> should address your concern?
>
> That commit adds the dependency of binutils on libctf.  But, if gdb is
> going to use libctf, then another one is needed for gdb. Otherwise, I
> think nothing ensures that libctf will be built before gdb.

If libctf were not built before gdb, gdb build would have failed
which is not the case. Will take another look.

> >>>> +#include <include/ctf.h>
>
> Tom> Probably just "ctf.h" here?  The top-level include directory is 
already
> Tom> on the include path.
>
> >> There is already a gdb/ctf.h for tracing?
>
> Aha, thanks for pointing that out.  In this case I think it would be
> better to rename gdb/ctf.h to something else.

While gdb/ctf.h is included in following files:

tracefile.c
tracepoint.c
mi/mi-main.c

it's only used in tracepoint.c. Will remove the include from tracefile.c 
and mi-main.c and rename it to "tracectf.h"?

> Tom> There's a type-safe registry API now.  I would prefer that for new
> Tom> code.
>
> >> Where can I get more info on this API?
>
 I thought I'd written a comment in registry.h, but I see I did not.
>
> The registry generates a template class named "TAG_key"; e.g. for the
> objfile registry it is called objfile_key.  You create your registry key
> using they type you plan to store.  So, from arm-tdep.c:
>
>     static objfile_key<arm_per_objfile> arm_objfile_data_key;
>
> If you use new/delete to manage the object that you store, then the
> above is enough.  For the htab case, see elfread.c:
>
>     static const struct objfile_key<htab, htab_deleter>
>       elf_objfile_gnu_ifunc_cache_data;
>
> The key has several methods, like "get" (to get the object), and "set"
> (to set the object).  If you're using plain new/delete, it will have an
> "emplace" method that you can use to create a new object.

Thanks for info. Will use the new API.