Re: [RFA] Select a particular mangling of a demangled symbol in lookup_block_symbol

Elena Zannoni
2002-03-19T22:20:12Z

Daniel Jacobowitz writes:
> I just described the problem this patch addresses in my testsuite patch;
> perhaps not the best place :) Here's the relevant bit:
>
> - Multiple symbols with the same demangled name. We can work around this
> for stabs, because we have the physname. We don't have that option for
> DWARF-2, and we shouldn't need to for stabs. I have a patch for the
> workaround. We get the [not-in-charge] constructor by default,
> unfortunately.
>
>
> What this means is that we call lookup_block_symbol on something like:
> _ZN3fooC1ERS_
> but get the information for:
> _ZN3fooC2ERS_
>
> The breakpoint ends up on the base-not-in-charge constructor.
>
> What we really SHOULD do is set it on both constructors silently, without
> even acknowledging that they are different functions, or else offer the user
> the choice. My preference is actually for the former. That requires
> support for a single function existing in multiple places, which will also
> give us nice things like better support for inlined functions with DWARF-2
> (which will always be somewhat shoddy due to the nature of inlining, in that
> it only occurs with lots of other optimization - but we can do much better
> than we do).
>
> Is this patch OK, or is it deemed too gross?
>
> --
> Daniel Jacobowitz Carnegie Mellon University
> MontaVista Software Debian GNU/Linux Developer
>
> 2002-02-14 Daniel Jacobowitz <drow@mvista.com>
>
> * symtab.h (lookup_block_symbol): Add mangled_name argument
> to prototype.
>
> * symmisc.c (maintenance_check_symtabs): Call lookup_block_symbol
> with new mangled_name argument.
> * linespec.c (decode_line_1): Likewise.
> * valops (value_of_this): Likewise.
> * symtab.c (lookup_transparent_type): Likewise.
> (lookup_symbol_aux): Likewise. Accept new mangled_name argument.
> (lookup_symbol): If we are given a mangled name, pass it down
> to lookup_symbol_aux.
> (lookup_block_symbol): If we are given a mangled name to check
> against, only return symbols which match it.
>
> @@ -567,6 +568,7 @@ lookup_symbol (const char *name, const s
> {
> char *modified_name = NULL;
> char *modified_name2 = NULL;
> + const char *mangled_name = NULL;
> int needtofreename = 0;
> struct symbol *returnval;
>
> @@ -592,13 +594,14 @@ lookup_symbol (const char *name, const s
> modified_name2 = cplus_demangle (modified_name, DMGL_ANSI | DMGL_PARAMS);
> if (modified_name2)
> {
> + mangled_name = name;
> modified_name = modified_name2;
> needtofreename = 1;
> }
> }
>
> - returnval = lookup_symbol_aux (modified_name, block, namespace,
> - is_a_field_of_this, symtab);
> + returnval = lookup_symbol_aux (modified_name, mangled_name, block,
> + namespace, is_a_field_of_this, symtab);
> if (needtofreename)
> xfree (modified_name2);
>

OK, approved. But I have my usual couple of questions:

Was the corresponding testsuite patch sorted out? Looks like it
wasn't. Does this patch have any effect on the testsuite results w/o
the testsuite patch?

In the above, should it be mangled_name = name or mangled_name =
modified_name? It would seem more uniform with the rest of the
function if we just used modified_name. Unless there is some problem
with case sensitivity, in which case, calling cplus_demangle with
modified_name seems wrong anyway. I.e. is it guaranteed that
case_sensitive_off is NOT in effect? Just out of curiosity What
would happen if the user sets the case sensitivity off?
Wouldn't it change _ZN3fooC1ERS_ to _zn3fooc1ers_ ? (of course the user
can always do a lot of things to screw himself up)

I guess what I am really asking is when is lookup_symbol called with a
mangled name. I tried to do "break foo::foo", and I never saw it called
with a mangled name.

Elena