On Wed, 27 Nov 2024, Jakub Jelinek wrote:
> Hi!
>
> As the following testcases show, in case of multi-word
> __sync_lock_test_and_set where we don't actually support atomics for that
> size (__int128 for x86_64 lp64 with -mno-cx16, long long for ia32 with
> -march=i{3,4}86), as the last fallback if we don't know anything else
> we just emit calls to __sync_lock_test_and_set_{8,16}. Those aren't defined
> in libatomic, but perhaps users could define them themselves.
> While __sync_lock_release if it gives up and has no way to emit the atomic
> store just does nothing at all, so no clear sign to the users something
> went wrong and that the code will not do what they expected.
> This regressed when __atomic_* support has been introduced, previously we
> would just emit those calls even in this case.
>
> The patch just emits the call as the last fallback.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
> 2024-11-27 Jakub Jelinek <ja...@redhat.com>
>
> PR target/117642
> * builtins.cc (expand_builtin_sync_lock_release): Change return type
> from void to rtx, return result of expand_atomic_store.
> (expand_builtin) <case BUILT_IN_SYNC_LOCK_RELEASE_16>: If
> expand_builtin_sync_lock_release returns NULL, do a break rather
> than return const0_rtx.
>
> * gcc.target/i386/pr117642-1.c: New test.
> * gcc.target/i386/pr117642-2.c: New test.
>
> --- gcc/builtins.cc.jj 2024-11-26 09:46:39.513228477 +0100
> +++ gcc/builtins.cc 2024-11-26 15:07:16.236123486 +0100
> @@ -6587,7 +6587,7 @@ expand_builtin_sync_lock_test_and_set (m
>
> /* Expand the __sync_lock_release intrinsic. EXP is the CALL_EXPR. */
>
> -static void
> +static rtx
> expand_builtin_sync_lock_release (machine_mode mode, tree exp)
> {
> rtx mem;
> @@ -6595,7 +6595,7 @@ expand_builtin_sync_lock_release (machin
> /* Expand the operands. */
> mem = get_builtin_sync_mem (CALL_EXPR_ARG (exp, 0), mode);
>
> - expand_atomic_store (mem, const0_rtx, MEMMODEL_SYNC_RELEASE, true);
> + return expand_atomic_store (mem, const0_rtx, MEMMODEL_SYNC_RELEASE, true);
> }
>
> /* Given an integer representing an ``enum memmodel'', verify its
> @@ -8605,8 +8605,9 @@ expand_builtin (tree exp, rtx target, rt
> case BUILT_IN_SYNC_LOCK_RELEASE_8:
> case BUILT_IN_SYNC_LOCK_RELEASE_16:
> mode = get_builtin_sync_mode (fcode - BUILT_IN_SYNC_LOCK_RELEASE_1);
> - expand_builtin_sync_lock_release (mode, exp);
> - return const0_rtx;
> + if (expand_builtin_sync_lock_release (mode, exp))
> + return const0_rtx;
> + break;
>
> case BUILT_IN_SYNC_SYNCHRONIZE:
> expand_builtin_sync_synchronize ();
> --- gcc/testsuite/gcc.target/i386/pr117642-1.c.jj 2024-11-26
> 15:18:07.270066467 +0100
> +++ gcc/testsuite/gcc.target/i386/pr117642-1.c 2024-11-26
> 15:19:20.467048094 +0100
> @@ -0,0 +1,19 @@
> +/* PR target/117642 */
> +/* { dg-do compile { target int128 } } */
> +/* { dg-options "-mno-cx16" } */
> +/* { dg-final { scan-assembler "__sync_lock_test_and_set_16" } } */
> +/* { dg-final { scan-assembler "__sync_lock_release_16" } } */
> +
> +__int128 t = 1;
> +
> +void
> +foo (void)
> +{
> + __sync_lock_test_and_set (&t, 1);
> +}
> +
> +void
> +bar (void)
> +{
> + __sync_lock_release (&t);
> +}
> --- gcc/testsuite/gcc.target/i386/pr117642-2.c.jj 2024-11-26
> 15:19:33.174871291 +0100
> +++ gcc/testsuite/gcc.target/i386/pr117642-2.c 2024-11-26
> 15:20:04.092441144 +0100
> @@ -0,0 +1,19 @@
> +/* PR target/117642 */
> +/* { dg-do compile { target ia32 } } */
> +/* { dg-options "-march=i486" } */
> +/* { dg-final { scan-assembler "__sync_lock_test_and_set_8" } } */
> +/* { dg-final { scan-assembler "__sync_lock_release_8" } } */
> +
> +long long t = 1;
> +
> +void
> +foo (void)
> +{
> + __sync_lock_test_and_set (&t, 1);
> +}
> +
> +void
> +bar (void)
> +{
> + __sync_lock_release (&t);
> +}
>
> Jakub
>
>
--
Richard Biener <rguent...@suse.de>
SUSE Software Solutions Germany GmbH,
Frankenstrasse 146, 90461 Nuernberg, Germany;
GF: Ivo Totev, Andrew McDonald, Werner Knoblich; (HRB 36809, AG Nuernberg)
