Re: find_pc_partial_function may produce the wrong answer

["H. J. Lu" <hjl at lucon dot org>]

On Wed, Jul 20, 2005 at 11:36:48AM -0400, Paul Koning wrote:
> >>>>> "Daniel" == Daniel Jacobowitz <drow@false.org> writes:
> 
>  Daniel> On Wed, Jul 20, 2005 at 10:28:14AM -0400, Paul Koning wrote:
>  >> I was tracking down a problem in my (modified) gdb, which showed
>  >> up when doing callstack tracing by reading the prologue.
>  >> (mips-tdep can do that, and in my version it does it most of the
>  >> time.)
>  >> 
>  >> The problem is that find_pc_partial_function is used to find the
>  >> start of the function, and it was producing the wrong answer.
>  >> Specifically, it produces the wrong answer when the function is in
>  >> a shared library.
>  >> 
>  >> The cause of the problem is that find_pc_partial_function looks up
>  >> the symbol in the msymtab, and that contains only external
>  >> symbols, not static symbols.  The comments in the source code
>  >> explicitly claim that it DOES contain static symbols, but "maint
>  >> print msymtab" clearly shows that it doesn't.  At least not for
>  >> MIPS shared libraries...
> 
>  Daniel> Is the shared library stripped?  I am absolutely positive
>  Daniel> that the minimal symbol table will include the static symtab
>  Daniel> - as long as there is one.
> 
>  Daniel> If for some reason in your modified GDB this is not the case,
>  Daniel> figure out why not.
> 
> It isn't related to the modified gdb; the stock gdb from CVS sources
> does the same.
> 
> It looks instead like there is something bizarre going on in the
> compile.  I looked in the build directory and found that the offending
> file (malloc.o) has no static syms in its symbol table according to
> readelf.  But when I repeat the compile by hand I get a rather
> different looking symbol table that does have them.  Need to track
> this down.

Are you using gcc 4.0/4.1 by any chance?


H.J.