Re: [RFA] minsyms.c: Fix switching to GNU v3 ABI

Daniel Jacobowitz
2004-03-10T15:08:24Z

On Wed, Mar 10, 2004 at 11:57:09AM +0100, Corinna Vinschen wrote:
> Hi,
>
> I was debugging a situation, in which an C++ object file has been build
> using v3 ABI, but GDB did not recognize it and was assuming v2 ABI. The
> target system is sh-elf, the compiler gcc 3.4.
>
> What I found is this:
>
> - The C++ ABI is set to v2 by default (gnu-v2-abi.c, _initialize_gnu_v2_abi).
>
> - While reading symbols from the object file, at one point elf_symfile_read()
> (elfread.c) is called.
>
> - elf_symfile_read() calls elf_symtab_read() which calls
> record_minimal_symbol() which calls prim_record_minimal_symbol_and_info().
>
> - In prim_record_minimal_symbol_and_info(), the symbol language is set to
> language_auto unconditionally.
>
> - After returning from elf_symtab_read(), install_minimal_symbols() is
> called. At the end of install_minimal_symbols() a loop over all msymbols
> tries to figure out if v3 ABI is used. This is done by requesting the
> demangeled name calling SYMBOL_DEMANGLED_NAME.
>
> The problem is that SYMBOL_LANGUAGE is still set to language_auto and
> the demangled name hasn't been generated at this point.

This is absolutely not what should happen.

prim_record_minimal_symbol_and_info:
SYMBOL_SET_NAMES (msymbol, (char *)name, strlen (name), objfile);

symbol_set_names:
-> symbol_find_demangled_name
if (gsymbol->language == language_cplus
|| gsymbol->language == language_auto)
{
demangled =
cplus_demangle (mangled, DMGL_PARAMS | DMGL_ANSI);
if (demangled != NULL)
{
gsymbol->language = language_cplus;
return demangled;
}
}

Please figure out why symbol_find_demangled_name has failed. It sounds
to me like you are having a problem with leading underscores, if I
remember my sh-elf-foo correctly.

> What's especially weird is the comment above install_minimal_symbols().
> It implies that the function will try to demangle all symbols to set
> the language correctly, but the function is not doing that. It would
> only recognize symbols which has already been demangeled but that just
> don't happen.

Comment is out of date.

--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer