Tested cris-elf, native x86_64-pc-linux-gnu and arm-eabi.
For arm-eabi, notably lacking any atomic support for the
default multilib, with --target_board=arm-sim it regressed
29_atomics/atomic_flag/cons/value_init.cc with the expected
linker failure due to lack of __atomic_test_and_set - which
is a good thing. With this one, there are 44 unexpected
FAILs for libstdc+++ at r14-4210-g94982a6b9cf4. This number
was 206 as late as r14-3470-g721f7e2c4e5e, but mitigated by
r14-3980-g62b29347c38394, deliberately. To fix the
regression, I'll do the same and follow up with adding
dg-require-thread-fence on
29_atomics/atomic_flag/cons/value_init.cc (and if approved,
commit it before this one).
Incidentally, the fortran test-results for arm-eabi are
riddled with missing-__sync_synchronize linker errors
causing some 18134 unexpected failures, where cris-elf has
121.
Ok to commit?
-- >8 --
Make __atomic_test_and_set consistent with other __atomic_ and __sync_
builtins: call a matching library function instead of emitting
non-atomic code when the target has no direct insn support.
There's special-case code handling targetm.atomic_test_and_set_trueval
!= 1 trying a modified maybe_emit_sync_lock_test_and_set. Previously,
if that worked but its matching emit_store_flag_force returned NULL,
we'd segfault later on. Now that the caller handles NULL, gcc_assert
here instead.
While the referenced PR:s are ARM-specific, the issue is general.
PR target/107567
PR target/109166
* builtins.cc (expand_builtin) <case BUILT_IN_ATOMIC_TEST_AND_SET>:
Handle failure from expand_builtin_atomic_test_and_set.
* optabs.cc (expand_atomic_test_and_set): When all attempts fail to
generate atomic code through target support, return NULL
instead of emitting non-atomic code. Also, for code handling
targetm.atomic_test_and_set_trueval != 1, gcc_assert result
from calling emit_store_flag_force instead of returning NULL.
---
gcc/builtins.cc | 5 ++++-
gcc/optabs.cc | 22 +++++++---------------
2 files changed, 11 insertions(+), 16 deletions(-)
diff --git a/gcc/builtins.cc b/gcc/builtins.cc
index 6e4274bb2a4e..40dfd36a3197 100644
--- a/gcc/builtins.cc
+++ b/gcc/builtins.cc
@@ -8387,7 +8387,10 @@ expand_builtin (tree exp, rtx target, rtx subtarget,
machine_mode mode,
break;
case BUILT_IN_ATOMIC_TEST_AND_SET:
- return expand_builtin_atomic_test_and_set (exp, target);
+ target = expand_builtin_atomic_test_and_set (exp, target);
+ if (target)
+ return target;
+ break;
case BUILT_IN_ATOMIC_CLEAR:
return expand_builtin_atomic_clear (exp);
diff --git a/gcc/optabs.cc b/gcc/optabs.cc
index 8b96f23aec05..e1898da22808 100644
--- a/gcc/optabs.cc
+++ b/gcc/optabs.cc
@@ -7080,25 +7080,17 @@ expand_atomic_test_and_set (rtx target, rtx mem, enum
memmodel model)
/* Recall that the legacy lock_test_and_set optab was allowed to do magic
things with the value 1. Thus we try again without trueval. */
if (!ret && targetm.atomic_test_and_set_trueval != 1)
- ret = maybe_emit_sync_lock_test_and_set (subtarget, mem, const1_rtx,
model);
-
- /* Failing all else, assume a single threaded environment and simply
- perform the operation. */
- if (!ret)
{
- /* If the result is ignored skip the move to target. */
- if (subtarget != const0_rtx)
- emit_move_insn (subtarget, mem);
+ ret = maybe_emit_sync_lock_test_and_set (subtarget, mem, const1_rtx,
model);
- emit_move_insn (mem, trueval);
- ret = subtarget;
+ if (ret)
+ {
+ /* Rectify the not-one trueval. */
+ ret = emit_store_flag_force (target, NE, ret, const0_rtx, mode, 0, 1);
+ gcc_assert (ret);
+ }
}
- /* Recall that have to return a boolean value; rectify if trueval
- is not exactly one. */
- if (targetm.atomic_test_and_set_trueval != 1)
- ret = emit_store_flag_force (target, NE, ret, const0_rtx, mode, 0, 1);
-
return ret;
}
--
2.30.2
