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Simon Marchi 8a91fbdf3b gdb/dwarf: disable per-BFD resource sharing for -readnow objfiles
New in v2:

  - Disable sharing only for -readnow objfiles, not all objfiles.

As described in PR 27541, we hit an internal error when loading a binary
the standard way and then loading it with the -readnow option:

    $ ./gdb -nx -q --data-directory=data-directory ~/a.out -ex "set confirm off" -ex "file -readnow ~/a.out"
    Reading symbols from /home/simark/a.out...
    Reading symbols from ~/a.out...
    /home/simark/src/binutils-gdb/gdb/dwarf2/read.c:8098: internal-error: void create_all_comp_units(dwarf2_per_objfile*): Assertion `per_objfile->per_bfd->all_comp_units.empty ()' failed.

This is a recurring problem that exposes a design issue in the DWARF
per-BFD sharing feature.  Things work well when loading a binary with
the same method (with/without index, with/without readnow) twice in a
row.  But they don't work so well when loading a binary with different
methods.  See this previous fix, for example:

    efb763a5ea ("gdb: check for partial symtab presence in dwarf2_initialize_objfile")

That one handled the case where the first load is normal (uses partial
symbols) and the second load uses an index.

The problem is that when loading an objfile with a method A, we create a
dwarf2_per_bfd and some dwarf2_per_cu_data and initialize them with the
data belonging to that method.  When loading another obfile sharing the
same BFD but with a different method B, it's not clear how to re-use the
dwarf2_per_bfd/dwarf2_per_cu_data previously created, because they
contain the data specific to method A.

I think the most sensible fix would be to not share a dwarf2_per_bfd
between two objfiles loaded with different methods.  That means that two
objfiles sharing the same BFD and loaded the same way would share a
dwarf2_per_bfd.  Two objfiles sharing the same BFD but loaded with
different methods would use two different dwarf2_per_bfd structures.

However, this isn't a trivial change.  So to fix the known issue quickly
(including in the gdb 10 branch), this patch just disables all
dwarf2_per_bfd sharing for objfiles using READNOW.

Generalize the gdb.base/index-cache-load-twice.exp test to test all
the possible combinations of loading a file with partial symtabs, index
and readnow.  Move it to gdb.dwarf2, since it really exercises features
of the DWARF reader.

gdb/ChangeLog:

	PR gdb/27541
	* dwarf2/read.c (dwarf2_has_info): Don't share dwarf2_per_bfd
	with objfiles using READNOW.

gdb/testsuite/ChangeLog:

	PR gdb/27541
	* gdb.base/index-cache-load-twice.exp: Remove.
	* gdb.base/index-cache-load-twice.c: Remove.
	* gdb.dwarf2/per-bfd-sharing.exp: New.
	* gdb.dwarf2/per-bfd-sharing.c: New.

Change-Id: I9ffcf1e136f3e75242f70e4e58e4ba1fd3083389
2021-03-30 13:37:11 -04:00
bfd asan: linker.c:2294:8: runtime error: load of value 253 2021-03-30 13:47:18 +10:30
binutils TRUE/FALSE simplification 2021-03-29 11:22:22 +10:30
config GCC_CET_HOST_FLAGS: Check if host supports multi-byte NOPs 2021-03-18 08:02:46 -07:00
contrib Import mklog.py from gcc repo 2020-09-25 10:24:44 -04:00
cpu opcodes int vs bfd_boolean fixes 2021-03-29 11:22:21 +10:30
elfcpp Add DWARF 5 support in gold. 2021-03-19 13:55:35 -07:00
etc Update year range in copyright notice of binutils files 2021-01-01 10:31:05 +10:30
gas x86: drop seg_entry 2021-03-30 14:09:41 +02:00
gdb gdb/dwarf: disable per-BFD resource sharing for -readnow objfiles 2021-03-30 13:37:11 -04:00
gdbserver Fix inverted logic bug 2021-03-30 09:23:11 -03:00
gdbsupport New memory-tag commands 2021-03-24 14:57:53 -03:00
gnulib gnulib: import gitlog-to-changelog 2021-03-24 19:35:40 -04:00
gold PR27625, powerpc64 gold __tls_get_addr calls 2021-03-30 13:38:41 +10:30
gprof Regen Makefile.in for jobserver.m4 aclocal.m4 dependency 2021-01-13 22:06:02 +10:30
include TRUE/FALSE simplification 2021-03-29 11:22:22 +10:30
intl intl: turn LIBINTL into -L / -l form 2021-02-10 15:26:57 +00:00
ld TRUE/FALSE simplification 2021-03-29 11:22:22 +10:30
libctf libctf: fix ELF-in-BFD checks in the presence of ASAN 2021-03-25 16:32:51 +00:00
libdecnumber
libiberty GCC_CET_HOST_FLAGS: Check if host supports multi-byte NOPs 2021-03-18 08:02:46 -07:00
opcodes x86: drop seg_entry 2021-03-30 14:09:41 +02:00
readline Fix Readline 8.1 build on mingw 2021-03-02 13:42:37 -07:00
sim sim: rename BUILD_LDFLAGS to LDFLAGS_FOR_BUILD 2021-03-13 11:21:13 -05:00
texinfo
zlib GCC: Check if AR works with --plugin and rc 2021-01-11 16:26:51 -08:00
.cvsignore
.gitattributes
.gitignore Add gnu global outputs to .gitignore 2020-12-02 10:00:27 -05:00
ar-lib
ChangeLog Add install dependencies for ld -> bfd and libctf -> bfd 2021-03-18 12:40:40 +00:00
compile
config-ml.in
config.guess Update config.sub and config.guess 2021-01-05 15:55:59 +10:30
config.rpath
config.sub config.sub update broke powerpc-eabivle 2021-01-07 08:56:28 +10:30
configure Remove arm-symbianelf 2021-02-09 23:36:16 +10:30
configure.ac Remove arm-symbianelf 2021-02-09 23:36:16 +10:30
COPYING
COPYING3
COPYING3.LIB
COPYING.LIB
COPYING.LIBGLOSS
COPYING.NEWLIB
depcomp
djunpack.bat
install-sh
libtool.m4 GCC: Check if AR works with --plugin and rc 2021-01-11 16:26:51 -08:00
lt~obsolete.m4
ltgcc.m4
ltmain.sh
ltoptions.m4
ltsugar.m4
ltversion.m4
MAINTAINERS
Makefile.def Add install dependencies for ld -> bfd and libctf -> bfd 2021-03-18 12:40:40 +00:00
Makefile.in Add install dependencies for ld -> bfd and libctf -> bfd 2021-03-18 12:40:40 +00:00
Makefile.tpl Add missing changes to Makefile.tpl 2021-02-28 04:39:38 -08:00
makefile.vms
missing
mkdep
mkinstalldirs
move-if-change
multilib.am
README
README-maintainer-mode
setup.com
src-release.sh src-release: fix indentation 2021-01-12 18:19:20 -05:00
symlink-tree
test-driver
ylwrap

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