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:
efb763a5ea35 ("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 Simon Marchi <simon.marchi@polymtl.ca>
+
+ PR gdb/27541
+ * dwarf2/read.c (dwarf2_has_info): Don't share dwarf2_per_bfd
+ with objfiles using READNOW.
+
2021-03-29 Tom Tromey <tromey@adacore.com>
* top.c (check_frame_language_change): Update.
{
dwarf2_per_bfd *per_bfd;
- /* We can share a "dwarf2_per_bfd" with other objfiles if the BFD
- doesn't require relocations. */
- if (!gdb_bfd_requires_relocations (objfile->obfd))
+ /* We can share a "dwarf2_per_bfd" with other objfiles if the
+ BFD doesn't require relocations.
+
+ We don't share with objfiles for which -readnow was requested,
+ because it would complicate things when loading the same BFD with
+ -readnow and then without -readnow. */
+ if (!gdb_bfd_requires_relocations (objfile->obfd)
+ && (objfile->flags & OBJF_READNOW) == 0)
{
/* See if one has been created for this BFD yet. */
per_bfd = dwarf2_per_bfd_bfd_data_key.get (objfile->obfd);
+2021-03-30 Simon Marchi <simon.marchi@polymtl.ca>
+
+ 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.
+
2021-03-30 Tom de Vries <tdevries@suse.de>
PR testsuite/27604
+++ /dev/null
-/* This testcase is part of GDB, the GNU debugger.
-
- Copyright 2020-2021 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/>. */
-
-int
-main (void)
-{
- return 0;
-}
+++ /dev/null
-# Copyright 2020-2021 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/>.
-
-# This test checks that loading a file twice with the index cache enabled does
-# not crash.
-
-standard_testfile
-
-lassign [remote_exec host mktemp -d] ret cache_dir
-
-# The output of mktemp contains an end of line, remove it.
-set cache_dir [string trimright $cache_dir \r\n]
-
-if { $ret != 0 } {
- fail "couldn't create temporary cache dir"
- return
-}
-
-save_vars { GDBFLAGS } {
- set GDBFLAGS "$GDBFLAGS -iex \"set index-cache directory $cache_dir\""
- set GDBFLAGS "$GDBFLAGS -iex \"set index-cache on\""
-
- if { [prepare_for_testing "failed to prepare" $testfile $srcfile \
- {debug additional_flags=-Wl,--build-id}] } {
- return
- }
-
- # This file command would generate an internal error.
- gdb_file_cmd [standard_output_file $testfile]
-}
--- /dev/null
+/* This testcase is part of GDB, the GNU debugger.
+
+ Copyright 2020-2021 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/>. */
+
+static
+int foo (int a, int b)
+{
+ return a + b;
+}
+
+int
+main (void)
+{
+ return foo (2, 3);
+}
--- /dev/null
+# Copyright 2020-2021 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/>.
+
+# This test checks that loading a file with different methods (partial symtabs,
+# index, readnow) does not crash.
+
+standard_testfile
+
+lassign [remote_exec host mktemp -d] ret cache_dir
+
+# The output of mktemp contains an end of line, remove it.
+set cache_dir [string trimright $cache_dir \r\n]
+
+if { $ret != 0 } {
+ fail "couldn't create temporary cache dir"
+ return
+}
+
+verbose -log "Index cache dir: $cache_dir"
+
+if { [build_executable "failed to prepare" $testfile $srcfile \
+ {debug additional_flags=-Wl,--build-id}] == -1 } {
+ return
+}
+
+# Populate the index-cache.
+with_test_prefix "populate index cache" {
+ clean_restart
+
+ gdb_test_no_output "set index-cache directory $cache_dir" \
+ "set index-cache directory"
+ gdb_test_no_output "set index-cache on"
+ gdb_test "file $binfile" "Reading symbols from .*" "file"
+}
+
+proc load_binary { method } {
+ global binfile
+ global hex
+
+ if { $method == "standard" } {
+ gdb_test "file $binfile" "Reading symbols from .*" "file"
+ } elseif { $method == "index" } {
+ gdb_test_no_output "set index-cache on"
+ gdb_test "file $binfile" "Reading symbols from .*" "file index"
+ gdb_test_no_output "set index-cache off"
+ } elseif { $method == "readnow" } {
+ gdb_test "file -readnow $binfile" \
+ "Reading symbols from .*Expanding full symbols from .*" \
+ "file readnow"
+ } else {
+ error "unknown method"
+ }
+
+ # Print a static function: seeing it and its signature confirms GDB
+ # sees some symbols.
+ gdb_test "print foo" " = {int \\(int, int\\)} $hex <foo>"
+}
+
+set methods {standard index readnow}
+
+foreach_with_prefix first $methods {
+ foreach_with_prefix second $methods {
+ foreach_with_prefix third $methods {
+ # Start with a clean GDB.
+ clean_restart
+
+ # Set the index cache dir, but don't enable the index-cache, it will
+ # be enabled only when needed, when loading a file with the "index"
+ # method.
+ gdb_test_no_output "set index-cache directory $cache_dir" \
+ "set index-cache directory"
+
+ # Avoid GDB asking whether we really want to load a new binary.
+ gdb_test_no_output "set confirm off"
+
+ with_test_prefix "load first" { load_binary $first }
+ with_test_prefix "load second" { load_binary $second }
+ with_test_prefix "load third" { load_binary $third }
+ }
+ }
+}
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