From 6a4757fe51a1c5ea31f33d8a83c03387302ac2d7 Mon Sep 17 00:00:00 2001 From: Philippe Mathieu-Daudé Date: Thu, 10 Dec 2020 17:47:40 +0400 Subject: qemu/atomic: Drop special case for unsupported compiler 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 3.4, __ATOMIC_RELAXED is defined, so the chunk to remove (which is x86-specific), isn't reached either. Signed-off-by: Philippe Mathieu-Daudé Reviewed-by: Marc-André Lureau Message-Id: <20201210134752.780923-2-marcandre.lureau@redhat.com> Signed-off-by: Paolo Bonzini --- include/qemu/atomic.h | 17 ----------------- 1 file changed, 17 deletions(-) (limited to 'include') diff --git a/include/qemu/atomic.h b/include/qemu/atomic.h index c1d211a351..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 !QEMU_GNUC_PREREQ(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 -- cgit v1.2.3-55-g7522