RE: [PATCH 1/1] gdb: Avoid warning for the jump command inside an inline function.

["Willgerodt, Felix" <felix.willgerodt@intel.com>]

> -----Original Message-----
> From: Andrew Burgess <aburgess@redhat.com>
> Sent: Freitag, 5. Mai 2023 18:22
> To: Willgerodt, Felix <felix.willgerodt@intel.com>; gdb-
> patches@sourceware.org
> Subject: RE: [PATCH 1/1] gdb: Avoid warning for the jump command inside an
> inline function.
> 
> "Willgerodt, Felix" <felix.willgerodt@intel.com> writes:
> 
> >> -----Original Message-----
> >> From: Willgerodt, Felix
> >> Sent: Dienstag, 25. April 2023 16:40
> >> To: Andrew Burgess <aburgess@redhat.com>; gdb-
> >> patches@sourceware.org
> >> Subject: RE: [PATCH 1/1] gdb: Avoid warning for the jump command
> inside an
> >> inline function.
> >>
> >> > -----Original Message-----
> >> > From: Andrew Burgess <aburgess@redhat.com>
> >> > Sent: Dienstag, 25. April 2023 16:09
> >> > To: Felix Willgerodt via Gdb-patches <gdb-patches@sourceware.org>;
> gdb-
> >> > patches@sourceware.org
> >> > Cc: Willgerodt, Felix <felix.willgerodt@intel.com>; Cristian Sandu
> >> > <cristian.sandu@intel.com>
> >> > Subject: Re: [PATCH 1/1] gdb: Avoid warning for the jump command
> inside
> >> > an inline function.
> >> >
> >> > Felix Willgerodt via Gdb-patches <gdb-patches@sourceware.org>
> writes:
> >> >
> >> > > When stopped inside an inline function, trying to jump to a different
> line
> >> > > of the same function currently results in a warning about jumping to
> >> > another
> >> > > function.  Fix this by taking inline functions into account.
> >> > >
> >> > > Before:
> >> > >   Breakpoint 1, function_inline (x=510) at jump-inline.cpp:22
> >> > >   22        a = a + x;             /* inline-funct */
> >> > >   (gdb) j 21
> >> > >   Line 21 is not in `function_inline(int)'.  Jump anyway? (y or n)
> >> > >
> >> > > After:
> >> > >   Breakpoint 2, function_inline (x=510) at jump-inline.cpp:22
> >> > >   22        a = a + x;            /* inline-funct */
> >> > >   (gdb) j 21
> >> > >   Continuing at 0x400679.
> >> > >
> >> > >   Breakpoint 1, function_inline (x=510) at jump-inline.cpp:21
> >> > >   21        a += 1020 + a;                /* increment-funct */
> >> > >
> >> > > This was regression-tested on X86-64 Linux.
> >> > >
> >> > > Co-Authored-by: Cristian Sandu <cristian.sandu@intel.com>
> >> > > ---
> >> > >  gdb/infcmd.c                           |  3 +-
> >> > >  gdb/testsuite/gdb.base/jump-inline.c   | 30 +++++++++++++++++
> >> > >  gdb/testsuite/gdb.base/jump-inline.exp | 45
> >> > ++++++++++++++++++++++++++
> >> > >  3 files changed, 77 insertions(+), 1 deletion(-)
> >> > >  create mode 100644 gdb/testsuite/gdb.base/jump-inline.c
> >> > >  create mode 100644 gdb/testsuite/gdb.base/jump-inline.exp
> >> > >
> >> > > diff --git a/gdb/infcmd.c b/gdb/infcmd.c
> >> > > index fd88b8ca328..40414bc9260 100644
> >> > > --- a/gdb/infcmd.c
> >> > > +++ b/gdb/infcmd.c
> >> > > @@ -1091,7 +1091,8 @@ jump_command (const char *arg, int
> from_tty)
> >> > >
> >> > >    /* See if we are trying to jump to another function.  */
> >> > >    fn = get_frame_function (get_current_frame ());
> >> > > -  sfn = find_pc_function (sal.pc);
> >> > > +  sfn = find_pc_sect_containing_function (sal.pc,
> >> > > +					  find_pc_mapped_section
> (sal.pc));
> >> >
> >> > I had a read through the discussion about whether find_pc_function
> >> > should return inline functions or not.  I don't know the history of this
> >> > code, so I don't know if there's a reason why it does what it does, but
> >> > looking at how it's used, I know there are some places in GDB where
> >> > find_pc_function is used when it shouldn't be.
> >> >
> >> > For example in edit_command (cli-cmds.c) I'm pretty sure the use of
> >> > find_pc_function is incorrect -- GDB will print the name of the
> >> > containing function, but then open the editor on the inlined function.
> >> >
> >> > As was said elsewhere, the biggest problem here will be lack of
> >> > testing.  What is really needed is an audit of each use of
> >> > find_pc_function and to ensure that each use is hit with an inline
> >> > function and a non-inline function.  Until then I think it's hard to be
> >> > certain about whether find_pc_function can safely be changed or not.
> >> > But doing that is no small task.
> >> >
> >> > Given that, I'm inclined to think we should take the patch as
> >> > presented.  If anyone ever does get around to sorting out this corner of
> >> > GDB then it's easy enough to revert this code back to use
> >> > find_pc_function.
> >> >
> >> > I do have one minor nit though...
> >> >
> >> > >    if (fn != nullptr && sfn != fn)
> >> > >      {
> >> > >        if (!query (_("Line %d is not in `%s'.  Jump anyway? "), sal.line,
> >> > > diff --git a/gdb/testsuite/gdb.base/jump-inline.c
> >> > b/gdb/testsuite/gdb.base/jump-inline.c
> >> > > new file mode 100644
> >> > > index 00000000000..17447c2d557
> >> > > --- /dev/null
> >> > > +++ b/gdb/testsuite/gdb.base/jump-inline.c
> >> > > @@ -0,0 +1,30 @@
> >> > > +/* Copyright 2021-2023 Free Software Foundation, Inc.
> >> > > +
> >> > > +   This program is free software; you can redistribute it and/or modify
> >> > > +   it under the terms of the GNU General Public License as published
> by
> >> > > +   the Free Software Foundation; either version 2 of the License, or
> >> > > +   (at your option) any later version.
> >> > > +
> >> > > +   This program is distributed in the hope that it will be useful,
> >> > > +   but WITHOUT ANY WARRANTY; without even the implied warranty
> of
> >> > > +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
> the
> >> > > +   GNU General Public License for more details.
> >> > > +
> >> > > +   You should have received a copy of the GNU General Public License
> >> > > +   along with this program.  If not, see
> <http://www.gnu.org/licenses/>.
> >> > */
> >> > > +
> >> > > +__attribute__((always_inline))
> >> > > +static void inline
> >> > > +function_inline (int x)
> >> > > +{
> >> > > +  int a = x;
> >> > > +  a += 1020 + a;		/* increment-funct. */
> >> > > +  a = a + x;			/* inline-funct. */
> >> > > +}
> >> > > +
> >> > > +int
> >> > > +main ()
> >> > > +{
> >> > > +  function_inline (510);
> >> > > +  return 0;			/* out-of-func. */
> >> > > +}
> >> > > diff --git a/gdb/testsuite/gdb.base/jump-inline.exp
> >> > b/gdb/testsuite/gdb.base/jump-inline.exp
> >> > > new file mode 100644
> >> > > index 00000000000..fef29fedb2f
> >> > > --- /dev/null
> >> > > +++ b/gdb/testsuite/gdb.base/jump-inline.exp
> >> > > @@ -0,0 +1,45 @@
> >> > > +# Copyright 2021-2023 Free Software Foundation, Inc.
> >> > > +
> >> > > +# This program is free software; you can redistribute it and/or modify
> >> > > +# it under the terms of the GNU General Public License as published
> by
> >> > > +# the Free Software Foundation; either version 3 of the License, or
> >> > > +# (at your option) any later version.
> >> > > +#
> >> > > +# This program is distributed in the hope that it will be useful,
> >> > > +# but WITHOUT ANY WARRANTY; without even the implied warranty
> of
> >> > > +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
> the
> >> > > +# GNU General Public License for more details.
> >> > > +#
> >> > > +# You should have received a copy of the GNU General Public License
> >> > > +# along with this program.  If not, see
> <http://www.gnu.org/licenses/>.
> >> > */
> >> > > +#
> >> > > +# Tests GDBs support for jump for inline functions.
> >> > > +
> >> > > +standard_testfile
> >> > > +
> >> > > +if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
> >> > > +    return -1
> >> > > +}
> >> > > +
> >> > > +if { ![runto_main] } {
> >> > > +    untested "failed to run to main"
> >> >
> >> > This untested line is not needed.  runto_main will emit a FAIL if
> >> > anything goes wrong.
> >>
> >> Right, I will remove it.
> >>
> >> > Reviewed-By: Andrew Burgess <aburgess@redhat.com>
> >> >
> >> > Thanks,
> >> > Andrew
> >>
> >> Thank you for your review and thorough feedback. I agree with your
> >> thoughts and conclusion.
> >> I am wondering though, as you gave me a reviewed-by but not an
> >> approved-by, should I wait a bit more or can I push this? I posted it
> originally
> >> in January and pinged a few times. So I tend to think that waiting more
> isn't
> >> worth it, but I am of course fine with doing that.
> >>
> >> Thanks,
> >> Felix
> >
> > *Pinging again after 10 days of no further comments*
> >
> > Is it okay to push this with the untested line removed?
> 
> As nobody has complained:
> 
> Approved-By: Andrew Burgess <aburgess@redhat.com>
> 
> Thanks,
> Andrew
> 

Thanks! I pushed this now.

Felix
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