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3eba3a011a
Recently I tried the m68k port of gdb. It had some issues, which are
fixed in this patch.
* Various types of return values were not being handled properly. In
particular:
* arrays are returned by following the same convention as
structures. This matters in languages like Ada, where an array
can in fact be returned as a value.
* "long double" was not being handled correctly in
m68k_svr4_return_value.
* GCC's m68k back end does not return vector types in registers, so
change gdb to follow.
* GCC's m68k back end doesn't faithfully implement the ABI, and so
some objects with unusual size (not possible in C, but possible in
Ada) are not returned correctly.
* gcc implements an m68k ABI variant that it simply describes as
"embedded". This ABI is similar to the SVR4 ABI, but rather than
returning pointer-typed values in %a0, such values are returned in
%d0. To support this, an ELF osabi sniffer is added.
* Commit 85f7484a ("m68k: tag floating-point ABI used") adds an
attribute that can be used to recognize when hard- or soft-float is
in use. gdb can now read this tag and choose the ABI accordingly.
I was unable to run the gdb test suite with this patch. Instead, I
tested it using qemu and the internal AdaCore test suite.
gdb/ChangeLog
2020-09-14 Tom Tromey <tromey@adacore.com>
* m68k-tdep.c (m68k_extract_return_value): Use
pointer_result_regnum.
(m68k_store_return_value): Likewise.
(m68k_reg_struct_return_p): Handle vectors and arrays.
(m68k_return_value): Handle arrays.
(m68k_svr4_return_value): Fix single-element aggregate handling.
Handle long double. Adjust for embedded ABI.
(m68k_svr4_init_abi): Set pointer_result_regnum.
(m68k_embedded_init_abi): New function.
(m68k_gdbarch_init): Handle Tag_GNU_M68K_ABI_FP.
(m68k_osabi_sniffer): New function.
(_initialize_m68k_tdep): Register osabi sniffer.
* m68k-tdep.h (struct gdbarch_tdep) <pointer_result_regnum>: New
member.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.