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Re: Simple but crucial bug fix to gdb
- To: Jim Blandy <jimb at cygnus dot com>
- Subject: Re: Simple but crucial bug fix to gdb
- From: Fernando Nasser <fnasser at cygnus dot com>
- Date: Fri, 01 Jun 2001 16:40:59 -0400
- CC: Charlie Mills <cmills at synopsys dot com>, gdb-patches at sourceware dot cygnus dot com
- Organization: Red Hat , Inc. - Toronto
- References: <3.0.5.32.20010530142745.01470ec0@pophost.pdxuxbre.lmc.com> <npofs8kkel.fsf@zwingli.cygnus.com>
Thank you Jim.
Fernando
Jim Blandy wrote:
>
> Charlie Mills <cmills@synopsys.com> writes:
> > Bug description: gdb 4.xx and 5.0 crashes while reading our executable.
> > Our executable is the result of linking objects compiled by gcc with
> > other objects compiled using SPARCworks CC. The stack trace is
> > appended at the end of this message.
>
> I managed to construct an executable that would crash GDB in the same
> way yours did (by editing a binary to get stabs of the sort Sun's
> compiler produces). I'm committing the patch below, which prevents
> the crashes. It's essentially the same fix as yours, except that
> there are two cases (static and global functions) that need attention,
> not one.
>
> I'm concerned that your builds are producing debugging entries for
> functions that appear to be outside of any compilation unit. GDB
> doesn't really know what to do with this; at the moment, it mostly
> ignores the function's entry. I wish I could play around with the
> situation and figure out what really needs to be done; with the
> current fix, I strongly suspect that GDB will be unable to find
> debugging information for some functions in some circumstances. So
> that the problem doesn't disappear from view entirely, my patch makes
> GDB complain (that's a technical term) when it sees debugging info
> like that present in your executable. Perhaps we'll find another
> case, and we'll be able to really fix the bug.
>
> In any case, thanks for the bug report.
>
> 2001-06-01 Jim Blandy <jimb@redhat.com>
>
> * partial-stab.h: New complaint: function_outside_compilation_unit.
> (case N_FUN: case 'f':, case N_FUN: case 'F':): If pst is zero,
> complain, and don't try to set pst's start address.
>
> Index: gdb/partial-stab.h
> ===================================================================
> RCS file: /cvs/src/src/gdb/partial-stab.h,v
> retrieving revision 1.9
> diff -c -r1.9 partial-stab.h
> *** gdb/partial-stab.h 2001/05/31 03:41:31 1.9
> --- gdb/partial-stab.h 2001/06/01 20:24:26
> ***************
> *** 40,45 ****
> --- 40,48 ----
>
> switch (CUR_SYMBOL_TYPE)
> {
> + static struct complaint function_outside_compilation_unit = {
> + "function `%s' appears to be defined outside of all compilation units", 0, 0
> + };
> char *p;
> /*
> * Standard, external, non-debugger, symbols
> ***************
> *** 576,581 ****
> --- 579,592 ----
> continue;
>
> case 'f':
> + if (! pst)
> + {
> + int name_len = p - namestring;
> + char *name = xmalloc (name_len + 1);
> + memcpy (name, namestring, name_len);
> + name[name_len] = '\0';
> + complain (&function_outside_compilation_unit, name);
> + }
> CUR_SYMBOL_VALUE += ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
> #ifdef DBXREAD_ONLY
> /* Kludges for ELF/STABS with Sun ACC */
> ***************
> *** 600,609 ****
> the bounds created by N_SO symbols. If that's the case
> use the address of this function as the low bound for
> the partial symbol table. */
> ! if (textlow_not_set
> ! || (pst && CUR_SYMBOL_VALUE < pst->textlow
> ! && CUR_SYMBOL_VALUE
> ! != ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile))))
> {
> pst->textlow = CUR_SYMBOL_VALUE;
> textlow_not_set = 0;
> --- 611,622 ----
> the bounds created by N_SO symbols. If that's the case
> use the address of this function as the low bound for
> the partial symbol table. */
> ! if (pst
> ! && (textlow_not_set
> ! || (CUR_SYMBOL_VALUE < pst->textlow
> ! && (CUR_SYMBOL_VALUE
> ! != ANOFFSET (objfile->section_offsets,
> ! SECT_OFF_TEXT (objfile))))))
> {
> pst->textlow = CUR_SYMBOL_VALUE;
> textlow_not_set = 0;
> ***************
> *** 620,625 ****
> --- 633,646 ----
> are put into the global psymtab like one would expect.
> They're also in the minimal symbol table. */
> case 'F':
> + if (! pst)
> + {
> + int name_len = p - namestring;
> + char *name = xmalloc (name_len + 1);
> + memcpy (name, namestring, name_len);
> + name[name_len] = '\0';
> + complain (&function_outside_compilation_unit, name);
> + }
> CUR_SYMBOL_VALUE += ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile));
> #ifdef DBXREAD_ONLY
> /* Kludges for ELF/STABS with Sun ACC */
> ***************
> *** 647,656 ****
> the bounds created by N_SO symbols. If that's the case
> use the address of this function as the low bound for
> the partial symbol table. */
> ! if (textlow_not_set
> ! || (pst && CUR_SYMBOL_VALUE < pst->textlow
> ! && CUR_SYMBOL_VALUE
> ! != ANOFFSET (objfile->section_offsets, SECT_OFF_TEXT (objfile))))
> {
> pst->textlow = CUR_SYMBOL_VALUE;
> textlow_not_set = 0;
> --- 668,679 ----
> the bounds created by N_SO symbols. If that's the case
> use the address of this function as the low bound for
> the partial symbol table. */
> ! if (pst
> ! && (textlow_not_set
> ! || (CUR_SYMBOL_VALUE < pst->textlow
> ! && (CUR_SYMBOL_VALUE
> ! != ANOFFSET (objfile->section_offsets,
> ! SECT_OFF_TEXT (objfile))))))
> {
> pst->textlow = CUR_SYMBOL_VALUE;
> textlow_not_set = 0;
--
Fernando Nasser
Red Hat - Toronto E-Mail: fnasser@redhat.com
2323 Yonge Street, Suite #300
Toronto, Ontario M4P 2C9