Add nvptx support to libatomic.
Given that atomic_test_and_set is not implemented for nvptx (PR96964), the
compiler translates __atomic_test_and_set falling back onto the "Failing all
else, assume a single threaded environment and simply perform the operation"
case in expand_atomic_test_and_set, so it doesn't map onto an actual atomic
operation.
Still, that counts as supported for the configure test of libatomic, so we
end up with HAVE_ATOMIC_TAS_1/2/4/8/16 == 1, and the corresponding
__atomic_test_and_set_1/2/4/8/16 in libatomic all using that non-atomic
implementation.
Fix this by adding an atomic_test_and_set expansion for nvptx, that uses
libatomics __atomic_test_and_set_1.
This again makes the configure tests for HAVE_ATOMIC_TAS_1/2/4/8/16 fail, so
instead we use this case in tas_n.c:
...
/* If this type is smaller than word-sized, fall back to a word-sized
compare-and-swap loop. */
bool
SIZE(libat_test_and_set) (UTYPE *mptr, int smodel)
...
which for __atomic_test_and_set_8 uses INVERT_MASK_8.
Add INVERT_MASK_8 in libatomic_i.h, as well as MASK_8.
Tested libatomic testsuite on nvptx.
gcc/ChangeLog:
PR target/96964
* config/nvptx/nvptx.md (define_expand "atomic_test_and_set"): New
expansion.
libatomic/ChangeLog:
PR target/96898
* configure.tgt: Add nvptx.
* libatomic_i.h (MASK_8, INVERT_MASK_8): New macro definition.
* config/nvptx/host-config.h: New file.
* config/nvptx/lock.c: New file.
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