Re: [PATCH 3/3] gdb/ctf: pass partial symtab's filename to buildsym_compunit

[Wei-min Pan via Gdb-patches <gdb-patches@sourceware.org>]

On 3/31/2022 2:20 PM, Simon Marchi wrote:
> I noticed that the CTF symbol reader passes the objfile's name to all
> buildsym_compunit instances it creates.  The result is that all
> compunit_symtabs created have the same name, that of the objfile:
>
>      { objfile /tmp/babeltrace-ctf/src/lib/.libs/libbabeltrace2.so.0.0.0 ((struct objfile *) 0x613000005d00)
>        { ((struct compunit_symtab *) 0x621000286760)
>          debugformat ctf
>          producer (null)
>          name libbabeltrace2.so.0.0.0
>          dirname (null)
>          blockvector ((struct blockvector *) 0x6210003911d0)
>          user ((struct compunit_symtab *) (null))
>              { symtab /tmp/babeltrace-ctf/src/lib/.libs/libbabeltrace2.so.0.0.0 ((struct symtab *) 0x6210003911f0)
>                fullname (null)
>                linetable ((struct linetable *) 0x0)
>              }
>        }
>        { ((struct compunit_symtab *) 0x621000275c10)
>          debugformat ctf
>          producer (null)
>          name libbabeltrace2.so.0.0.0
>          dirname (null)
>          blockvector ((struct blockvector *) 0x621000286710)
>          user ((struct compunit_symtab *) (null))
>              { symtab /tmp/babeltrace-ctf/src/lib/.libs/libbabeltrace2.so.0.0.0 ((struct symtab *) 0x621000286730)
>                fullname (null)
>                linetable ((struct linetable *) 0x0)
>              }
>        }
>
> Notice the two "name libbabeltrace2.so.0.0.0".
>
> Change it to pass the partial_symtab's filename instead.  The output
> becomes:
>
>      { objfile /tmp/babeltrace-ctf/src/lib/.libs/libbabeltrace2.so.0.0.0 ((struct objfile *) 0x613000005d00)
>        { ((struct compunit_symtab *) 0x621000295610)
>          debugformat ctf
>          producer (null)
>          name libbabeltrace2.so.0.0.0
>          dirname (null)
>          blockvector ((struct blockvector *) 0x6210003a15d0)
>          user ((struct compunit_symtab *) (null))
>              { symtab /tmp/babeltrace-ctf/src/lib/.libs/libbabeltrace2.so.0.0.0 ((struct symtab *) 0x6210003a15f0)
>                fullname (null)
>                linetable ((struct linetable *) 0x0)
>              }
>        }
>        { ((struct compunit_symtab *) 0x621000288700)
>          debugformat ctf
>          producer (null)
>          name current-thread.c
>          dirname (null)
>          blockvector ((struct blockvector *) 0x6210002955c0)
>          user ((struct compunit_symtab *) (null))
>              { symtab /home/simark/src/babeltrace/src/lib/current-thread.c ((struct symtab *) 0x6210002955e0)
>                fullname (null)
>                linetable ((struct linetable *) 0x0)
>              }
>        }
>
> Note that the first compunit_symtab still has libbabeltrace2.so.0.0.0 as
> its name.  This is because the CTF symbol reader really creates a
> partial symtab named like this.  It appears to be because the debug info
> contains information that has been factored out of all CUs and is at the
> "top-level" of the objfile, outside any real CU.  So it creates a
> partial symtab and an artificial CU that's named after the objfile.
>
> Change-Id: I576316bab2a3668adf87b4e6cebda900a8159b1b
> ---
>   gdb/ctfread.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/gdb/ctfread.c b/gdb/ctfread.c
> index 8636692e2e1b..7f7e09638a40 100644
> --- a/gdb/ctfread.c
> +++ b/gdb/ctfread.c
> @@ -1253,7 +1253,7 @@ ctf_start_symtab (ctf_psymtab *pst,
>   
>     ccp = &pst->context;
>     ccp->builder = new buildsym_compunit
> -		       (of, of->original_name, nullptr,
> +		       (of, pst->filename, nullptr,
>   		       language_c, text_offset);

Looks good. Thanks.

>     ccp->builder->record_debugformat ("ctf");
>   }