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Re: [RFA] import drow dbxread.c fix to branch
On Thu, Apr 04, 2002 at 02:27:05PM -0500, Elena Zannoni wrote:
> Daniel Jacobowitz writes:
> > On Wed, Apr 03, 2002 at 11:36:06PM -0600, Michael Elizabeth Chastain wrote:
> > > DanielJ writes:
> > > > Only shows on GCC 3.1, eh? I'll try to look at it later, but I have no
> > > > post-3.0 toolchain installed right now. Actually, I should
> > > > investigate, to make sure it isn't a 3.1 regression...
> > >
> > > On the next spin, I'll make a special report of regressions for gcc
> > > 3.0.4 versus gcc-3_1-branch. You can already look at "difference by gcc"
> > > in the regular report if you want to pick up a hot spot or two.
> > >
> > > BTW my test harness now saves the whole test directory, including all
> > > the executable files. In fact I'll just throw some tarball up in my
> > > ftp directory in case it might help someone:
> > >
> > > ftp://ftp.shout.net/pub/users/mec/gdb/for-pr-gdb-381.tar.gz
> > > ftp://ftp.shout.net/pub/users/mec/gdb/for-pr-gdb-381-src.tar.gz
> >
> > Thanks. It does help - that was pretty easy, actually :). I've found
> > the bug; mi-cmd-disassemble does not recognize '0' line numbers, and it
> > needs to. I don't know why only 3.1 triggers this. Probably a
> > function padding thing; the end of the previous function seems to share
> > a PC with the beginning of the one being listed. Here's a patch;
> > Andrew, how's this look?
> >
>
> Take a look at the way gdbtk does it, in
> gdbtk/generic/gdbtk-cmd.c:gdb_disassemble_driver().
> Can we adopt that solution?
>
> (I really can't wait until we can get rid of this duplication/triplication of
> disassembly code. I think I'll start cleaning some things up).
I'm not sure. That code assumes a different meaning of line==0 than
the one we're using. Particularly, if I understand correctly, the
meaning in gdbtk comes from a set of Cygnus-internal stabs for handling
live range splitting, which never made it into any public GCC and are
completely obsoleted by DWARF-2. I prefer:
> + /* Skip any end-of-function markers. */
> + if (le[i].line == 0)
> + continue;
> +
to:
/* GCC sometimes emits line directives with a linenumber
of 0. It does this to handle live range splitting.
This may be a bug, but we need to be able to handle it.
For now, use the previous instructions line number.
Since this is a bit of a hack anyway, we will just lose
if the bogus sline is the first line of the range. For
functions, I have never seen this to be the case. */
if (le[i].line != 0)
{
mle[newlines].line = le[i].line;
}
else
{
if (newlines > 0)
mle[newlines].line = mle[newlines - 1].line;
}
i.e. skip the line, not fake up a line number for it. It's a
special-purpose marker, not a generic line number.
If you agree with me, want me to update gdbtk's version to match? Does
this same code exist in a third location?
--
Daniel Jacobowitz Carnegie Mellon University
MontaVista Software Debian GNU/Linux Developer