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Joel Brobecker 14aba1ac0d Lift DWARF unwinder restriction in dwarf2-frame.c::dwarf2_frame_cfa
GDB is currently broken on all SPARC targets when using GCC 4.9.
When trying to print any local variable:

    (gdb) p x
    can't compute CFA for this frame

This is related to the fact that the compiler now generates DWARF 4
debugging info by default, and in particular that it now emits
DW_OP_call_frame_cfa, which triggers a limitation in dwarf2_frame_cfa:

   /* This restriction could be lifted if other unwinders are known to
      compute the frame base in a way compatible with the DWARF
      unwinder.  */
   if (!frame_unwinder_is (this_frame, &dwarf2_frame_unwind)
       && !frame_unwinder_is (this_frame, &dwarf2_tailcall_frame_unwind))
     error (_("can't compute CFA for this frame"));

We couldn't append the dwarf2 unwinder to all SPARC targets because
it does not work properly with StackGhost:
    https://www.sourceware.org/ml/gdb-patches/2014-07/msg00012.html

We also later discovered that using the DWARF2 unwinder means
using it for computing the function's return address, which
is buggy when it comes to functions returning a struct (where
the return address is saved-pc+12 instead of saved-pc+8).
This is because GCC is emitting the info about the return address
as %o7/%i7 instead of the actual return address.  For functions
that have debugging info, we compensate by looking at the function's
return type and add the extra +4, but for function without debug
info, we're stuck.

EricB and I twisted the issue in all the directions we could think of,
and unfortunately couldn't find a way to make it work without
introduction one regression or another.

But, stepping back a little, just removing the restriction seems to work
well for us on all both sparc-elf and {sparc,sparc64}-solaris.
After reviewing the previous discussions about this test, I could
not figure out whether some unwinders were already known to have
incompatible CFAs or if the concern was purely theoretical:
    https://www.sourceware.org/ml/gdb-patches/2009-06/msg00191.html
    https://www.sourceware.org/ml/gdb-patches/2009-07/msg00570.html
    https://www.sourceware.org/ml/gdb-patches/2009-09/msg00027.html

At the moment, we took the approach of trying it out, and see what
happens...

gdb/ChangeLog:

        PR backtrace/16215:
        * dwarf2-frame.c (dwarf2_frame_cfa): Remove the restriction
        the frame unwinder must either be the dwarf2_frame_unwind
        or the dwarf2_tailcall_frame_unwind.  Verify that this_frame's
        stack_addr is valid before calling get_frame_base.  Throw
        an error if not valid.

Tested on sparc-solaris and sparc-elf with AdaCore's testsuite
(the FSF testsuite crashes all of AdaCore's solaris machines).
2014-12-13 08:26:31 -05:00
bfd Automatic date update in version.in 2014-12-13 00:00:11 +00:00
binutils Fix a few moere memory access violations. 2014-12-11 20:25:05 +00:00
config Fix --diable-shared --enable-plugins build breakage 2014-08-19 21:59:56 +09:30
cpu or1k: add missing l.msync, l.psync and l.psync instructions. 2014-07-20 20:26:09 +03:00
elfcpp Add tls support to gold aarch64 backend. 2014-09-17 14:24:10 -07:00
etc PR external/{16327,16328}: Remove etc/configure.texi and etc/standards.texi. 2014-06-27 11:33:25 +02:00
gas PowerPC register numbers in DWARF 2014-12-13 00:11:36 +10:30
gdb Lift DWARF unwinder restriction in dwarf2-frame.c::dwarf2_frame_cfa 2014-12-13 08:26:31 -05:00
gold Give informative error message for stub-group-size 2014-12-10 15:39:13 -08:00
gprof Update libtool.m4 from GCC trunk 2014-11-24 09:14:09 -08:00
include add gcc/gdb interface files 2014-12-12 22:23:53 +01:00
intl merge from gcc 2010-09-27 21:01:18 +00:00
ld Don't always build coffgen.o 2014-12-10 23:13:49 +10:30
libdecnumber PR c/59871 c/ * c-typeck.c (build_compound_expr): Warn even for right-hand operand of a comma expression. (emit_side_effect_warnings): Likewise. libdecnumber/ * decNumberLocal.h (UBFROMUS, UBFROMUI): Remove last argument. testsuite/ * gcc.dg/20020220-2.c: Adjust dg-warning message. * gcc.dg/pr59871.c: New test. 2014-05-08 10:18:28 -06:00
libiberty Sync libiberty from GCC 2014-11-17 03:30:13 +01:00
opcodes Add zex instructions for moxie port 2014-12-12 08:45:25 -05:00
readline readline/search.c: Remove useless parameter '0' for rl_message() 2014-09-22 09:52:06 -04:00
sim Add zex instruction support for moxie port 2014-12-12 08:45:25 -05:00
texinfo
.cvsignore
.gitattributes Add a .gitattributes file for use with git-merge-changelog 2014-07-25 18:07:23 -04:00
.gitignore Sync the root .gitignore file with GCC's. 2013-01-11 15:17:35 +00:00
ChangeLog Update from upstream config repo 2014-12-06 16:09:33 +01:00
compile Update from upstream Automake 2014-11-16 13:43:48 +01:00
config-ml.in * config-ml.in: Don't handle arc-*-elf*. 2011-03-22 20:01:13 +00:00
config.guess Update config.{guess,sub} from upstream config repo 2014-11-16 20:15:00 +01:00
config.rpath Remove freebsd1 from libtool.m4 macros and config.rpath. 2011-02-13 21:00:14 +00:00
config.sub Update from upstream config repo 2014-12-06 16:09:33 +01:00
configure Add aarch64 to list of targets that support gold. 2014-10-03 14:48:14 -07:00
configure.ac Add aarch64 to list of targets that support gold. 2014-10-03 14:48:14 -07:00
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS 2013-01-07 Jeff Johnston <jjohnstn@redhat.com> 2013-01-07 21:39:26 +00:00
COPYING.NEWLIB 2013-10-01 Jeff Johnston <jjohnstn@redhat.com> 2013-10-01 18:14:04 +00:00
depcomp Update from upstream Automake 2014-11-16 13:43:48 +01:00
djunpack.bat
install-sh Update from upstream Automake 2014-11-16 13:43:48 +01:00
libtool.m4 Update libtool.m4 from GCC trunk 2014-11-24 09:14:09 -08:00
lt~obsolete.m4
ltgcc.m4
ltmain.sh PR target/59788 2014-02-06 11:01:57 +01:00
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS Update description of ownership of files in include/ 2014-11-04 16:14:14 -08:00
Makefile.def PR sanitizer/56781 * Makefile.def: Set bootstrap=true; for host fixincludes. * configure.ac: Don't bootstrap host fixincludes unless --with-build-config=bootstrap-{a,ub}san. * Makefile.in: Regenerated. * configure: Regenerated. 2014-05-08 10:18:30 -06:00
Makefile.in PR sanitizer/56781 * Makefile.def: Set bootstrap=true; for host fixincludes. * configure.ac: Don't bootstrap host fixincludes unless --with-build-config=bootstrap-{a,ub}san. * Makefile.in: Regenerated. * configure: Regenerated. 2014-05-08 10:18:30 -06:00
Makefile.tpl PR bootstrap/58572 * Makefile.tpl (POSTSTAGE1_CXX_EXPORT): Use -isystem instead of -I for libstdc++-v3 includes if $(LEAN). * Makefile.in: Regenerated. 2014-05-08 10:18:29 -06:00
makefile.vms
missing Update from upstream Automake 2014-11-16 13:43:48 +01:00
mkdep
mkinstalldirs Update from upstream Automake 2014-11-16 13:43:48 +01:00
move-if-change Update `move-if-change' from gnulib 2014-11-16 17:04:02 +01:00
README
README-maintainer-mode
setup.com
src-release.sh src-release.sh: configure using --target. 2014-10-15 09:50:53 +02:00
symlink-tree
ylwrap Update from upstream Automake 2014-11-16 13:43:48 +01:00

		   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.