Re: [PATCH v2 1/1] dwarf, fortran: add support for DW_TAG_entry_point

[Kevin Buettner <kevinb@redhat.com>]

On Thu, 14 Apr 2022 11:41:08 +0200
Nils-Christian Kempke <nils-christian.kempke@intel.com> wrote:

> Fortran provides additional entry points for subroutines and functions.
> These entry points may use only a subset (or a different set) of the
> parameters of the original subroutine.  The entry points may be described
> via the DWARF tag DW_TAG_entry_point.
> 
> This commit adds support for parsing the DW_TAG_entry_point DWARF tag.
> Currently, between ifx/ifort/gfortran, only ifort is actually emitting
> this tag.  Both, ifx and gfortran use the DW_TAG_subprogram tag as
> workaround/alternative.  Thus, this patch really only adds more ifort
> support.  Even so, some of the attached tests still fail for ifort, due
> to some wrong line info generated for the entry points in ifort.
> 
> After this patch it is possible to set a breakpoint in gdb with the
> ifort compiled example at the entry points 'foo' and 'foobar', which was not
> possible before.
> 
> As gcc and ifx do not emit the tag I also added a test to gdb.dwarf2
> which uses some underlying c compiled code and adds some Fortran style DWARF
> to it emitting the DW_TAG_entry_point.  Before this patch it was not
> possible to actually define breakpoint at the entry point tags.
> 
> For gfortran there actually exists a bug on bugzilla, asking for the use
> of DW_TAG_entry_point over DW_TAG_subprogram:
> 
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=37134
> 
> This patch was originally posted here
> 
> https://sourceware.org/legacy-ml/gdb-patches/2017-07/msg00317.html
> 
> but its review/pinging got lost after a while.  I reworked it to fit the
> current GDB.
> 
> Co-authored-by: Bernhard Heckel <bernhard.heckel@intel.com>
> Co-authored-by: Tim Wiederhake  <tim.wiederhake@intel.com>
> 
> Signed-off-by: Nils-Christian Kempke <nils-christian.kempke@intel.com>

Okay.

(Thanks for adding the new test!)

Kevin