These tests previously passed, now they fail. Apparently the "cxx-mem-model merge [6 of 9]" (formally a change in the range 181027:181034) exposed or caused these regressions. Since then they fail as follows: Running /tmp/hpautotest-gcc1/gcc/libstdc++-v3/testsuite/libstdc++-dg/conformance.exp ... ... FAIL: 29_atomics/atomic_flag/clear/1.cc (test for excess errors) WARNING: 29_atomics/atomic_flag/clear/1.cc compilation failed to produce executable FAIL: 29_atomics/atomic_flag/test_and_set/explicit.cc (test for excess errors) WARNING: 29_atomics/atomic_flag/test_and_set/explicit.cc compilation failed to produce executable FAIL: 29_atomics/atomic_flag/test_and_set/implicit.cc (test for excess errors) The messages in libstdc++.log are similar, but have changed since the above. At r181162 they are as follows: Executing on host: /tmp/hpautotest-gcc1/cris-elf/gccobj/./gcc/g++ -shared-libgcc -B/tmp/hpautotest-gcc1/cris-elf/gccobj/./gcc -nostdinc++ -L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/src -L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/src/.libs -nostdinc -B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/newlib/ -isystem /tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/newlib/targ-include -isystem /tmp/hpautotest-gcc1/gcc/newlib/libc/include -B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libgloss/cris -L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libgloss/libnosys -L/tmp/hpautotest-gcc1/gcc/libgloss/cris -B/tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/bin/ -B/tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/lib/ -isystem /tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/include -isystem /tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/sys-include -B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./libgloss/cris/ -L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./libgloss/cris -L/tmp/hpautotest-gcc1/gcc/libgloss/cris -B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./libstdc++-v3/src/.libs -g -O2 -D_GLIBCXX_ASSERT -fmessage-length=0 -ffunction-sections -fdata-sections -g -O2 -g -O2 -DLOCALEDIR="." -nostdinc++ -I/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/cris-elf -I/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include -I/tmp/hpautotest-gcc1/gcc/libstdc++-v3/libsupc++ -I/tmp/hpautotest-gcc1/gcc/libstdc++-v3/include/backward -I/tmp/hpautotest-gcc1/gcc/libstdc++-v3/testsuite/util /tmp/hpautotest-gcc1/gcc/libstdc++-v3/testsuite/29_atomics/atomic_flag/clear/1.cc -std=gnu++0x ./libtestc++.a -isystem /tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./newlib/targ-include -isystem /tmp/hpautotest-gcc1/gcc/newlib/libc/include -B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./libgloss/cris/ -L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./libgloss/cris -L/tmp/hpautotest-gcc1/gcc/libgloss/cris -B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./newlib/ -L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/./newlib -sim3 -lm -o ./1.exe (timeout = 600) /tmp/ccX4JE6W.o: In function `ZNSt11atomic_flag5clearESt12memory_order': /tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/bits/atomic_base.h:311: undefined reference to `std::atomic_thread_fence(std::memory_order)' /tmp/ccX4JE6W.o: In function `ZNSt11atomic_flag12test_and_setESt12memory_order': /tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/bits/atomic_base.h:274: undefined reference to `__sync_lock_test_and_set_1' collect2: error: ld returned 1 exit status compiler exited with status 1 output is: /tmp/ccX4JE6W.o: In function `ZNSt11atomic_flag5clearESt12memory_order': /tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/bits/atomic_base.h:311: undefined reference to `std::atomic_thread_fence(std::memory_order)' /tmp/ccX4JE6W.o: In function `ZNSt11atomic_flag12test_and_setESt12memory_order': /tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/bits/atomic_base.h:274: undefined reference to `__sync_lock_test_and_set_1' collect2: error: ld returned 1 exit status with the 29_atomics/atomic_flag/test_and_set/explicit.cc test only having the last undefined reference. Author of the suspect patches in the revision range CC:ed. cris-elf does not have any back-end atomicity support patterns specified, there's just the libstdc++-v3/config/cpu/cris atomicity header files, apparently obsoleted by the cxx-mem-model merge.
The issue here is no atomic support whatsoever. The standard now *requires* that atomic_flag be implementable in a lock free manner for compliance. In order to support atomic_flag in a lock free manner on a target, we need at a minimum the legacy __sync_lock_test_and_set and __sync_lock_release to be implemented. Previous to this release, if atomic_flag couldn't be implemented lock free, it was implemented with locks. libstdc++-v3 no longer supports any locked implementations.
Author: amacleod Date: Thu Nov 10 20:38:33 2011 New Revision: 181271 URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=181271 Log: PR middle-end/51038 libstdc++-v3 * include/bits/atomic_base.h (atomic_thread_fence): Call built-in. (atomic_signal_fence): Call built-in. (test_and_set, clear): Call new atomic built-ins. gcc * builtins.c (expand_builtin_atomic_clear): New. Expand atomic_clear. (expand_builtin_atomic_test_and_set): New. Expand atomic test_and_set. (expand_builtin): Add cases for test_and_set and clear. * sync-builtins.def (BUILT_IN_ATOMIC_TEST_AND_SET): New. (BUILT_IN_ATOMIC_CLEAR): New. testsuite * gcc.dg/atomic-invalid.c: Add test for invalid __atomic_clear models. * gcc.dg/atomic-flag.c: New. Test __atomic_test_and_set and __atomic_clear. Added: trunk/gcc/testsuite/gcc.dg/atomic-flag.c Modified: trunk/gcc/ChangeLog trunk/gcc/builtins.c trunk/gcc/sync-builtins.def trunk/gcc/testsuite/ChangeLog trunk/gcc/testsuite/gcc.dg/atomic-invalid.c trunk/libstdc++-v3/ChangeLog trunk/libstdc++-v3/include/bits/atomic_base.h
Is this now fixed (and thus, can this bug be closed)?
(In reply to comment #3) > Is this now fixed (and thus, can this bug be closed)? Yes, done. Thanks for the reminder.