Re: should minimal symbols be able to force lookup_symbol to return NULL?

[Jim Blandy <jimb at redhat dot com>]

David Carlton <carlton@math.stanford.edu> writes:
> On 28 Oct 2002 11:16:31 -0800, David Carlton <carlton@math.Stanford.EDU> said:
> 
> > Currently, it seems to me that, when lookup_symbol_aux is searching
> > the minsyms, if it finds a minsym without a corresponding symbol,
> > then lookup_symbol_aux will return NULL without proceeding on to the
> > check of the static symtabs/psymtabs.
> 
> This isn't true: it only sometimes does that (if either it can find a
> symtab at the right address or if it wants to try a name lookup with
> the mangled name).  Sigh.  This is a mess.

Yeah.  I don't think that's deliberate behavior, since it doesn't
happen under any consistent circumstances.

As far as I can tell, the minsyms are in lookup_symtab_aux strictly as
a faster way to find the right psymtab: look up the minsym by name,
get its address, find the psymtab that covers that address.  This does
an address range comparison per psymtab, instead of a hash probe.  But
we know that our psymtab address ranges are inaccurate at times (C++
can scatter a single CU's code across disjoint parts of the text
segment), so this seems like a rotten approach.

I suspect that HP found the same problem you have: look at Rich
Title's comment below (starting with "RT:"):

#ifdef HPUXHPPA

  /* Check for the possibility of the symbol being a function or
     a global variable that is stored in one of the minimal symbol tables.
     The "minimal symbol table" is built from linker-supplied info.

     RT: I moved this check to last, after the complete search of
     the global (p)symtab's and static (p)symtab's. For HP-generated
     symbol tables, this check was causing a premature exit from
     lookup_symbol with NULL return, and thus messing up symbol lookups
     of things like "c::f". It seems to me a check of the minimal
     symbol table ought to be a last resort in any case. I'm vaguely
     worried about the comment below which talks about FORTRAN routines "foo_"
     though... is it saying we need to do the "minsym" check before
     the static check in this case? 
   */

Perhaps we should remove the HPUXHPPA conditional, and just do it the
HPUXHPPA way all the time.