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[PATCH v2 02/13] qemu/atomic: Drop special case for unsupported compiler
From: |
marcandre . lureau |
Subject: |
[PATCH v2 02/13] qemu/atomic: Drop special case for unsupported compiler |
Date: |
Thu, 26 Nov 2020 15:29:04 +0400 |
From: Philippe Mathieu-Daudé <philmd@redhat.com>
Since commit efc6c070aca ("configure: Add a test for the
minimum compiler version") the minimum compiler version
required for GCC is 4.8, which has the GCC BZ#36793 bug fixed.
We can safely remove the special case introduced in commit
a281ebc11a6 ("virtio: add missing mb() on notification").
With clang 3.8 (xenial amd64) __ATOMIC_RELAXED is defined, so the chunk
to remove (which is x86-specific), isn't reached.
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
---
include/qemu/atomic.h | 17 -----------------
1 file changed, 17 deletions(-)
diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h
index c409257c11..8f4b3a80fb 100644
--- a/include/qemu/atomic.h
+++ b/include/qemu/atomic.h
@@ -241,23 +241,6 @@
#else /* __ATOMIC_RELAXED */
-/*
- * We use GCC builtin if it's available, as that can use mfence on
- * 32-bit as well, e.g. if built with -march=pentium-m. However, on
- * i386 the spec is buggy, and the implementation followed it until
- * 4.3 (http://gcc.gnu.org/bugzilla/show_bug.cgi?id=36793).
- */
-#if defined(__i386__) || defined(__x86_64__)
-#if !G_GNUC_CHECK_VERSION(4, 4)
-#if defined __x86_64__
-#define smp_mb() ({ asm volatile("mfence" ::: "memory"); (void)0; })
-#else
-#define smp_mb() ({ asm volatile("lock; addl $0,0(%%esp) " ::: "memory");
(void)0; })
-#endif
-#endif
-#endif
-
-
#ifdef __alpha__
#define smp_read_barrier_depends() asm volatile("mb":::"memory")
#endif
--
2.29.0