We wrongly assumed that on x86-32 when '__i386__' is defined but none of
'__i486__', '__i586__' or '__i686__' that the target arch is a literal
i386 cpu without the cmpxchg instructions. However, when building with
'-march=core2' we get '__i386__' but none of the others even if the arch
is newer than an i686.
Change the compat code to use the '__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4'
builtin define to detect an x86-32 system without the cmpxchg
instructions.
Since this builtin define was introduced in GCC 4.3 and Clang 3.3,
building with older compilers on any x86-32 system will enable the
compat layer regardless of the availability of the instructions.
Change-Id: I8329431e55d778405b2ca7007d90c2c6e5cdd426
Signed-off-by: Michael Jeanson <mjeanson@efficios.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
#define URCU_ARCH_AMD64 1
#include <urcu/arch/x86.h>
#define URCU_ARCH_AMD64 1
#include <urcu/arch/x86.h>
-#elif (defined(__i486__) || defined(__i586__) || defined(__i686__))
+#elif (defined(__i386__) || defined(__i386) || defined(__i486__) || defined(__i586__) || defined(__i686__))
-#include <urcu/arch/x86.h>
-
-#elif (defined(__i386__) || defined(__i386))
+/*
+ * URCU_ARCH_X86_NO_CAS enables a compat layer that will detect the presence of
+ * the cmpxchg instructions at runtime and provide a compat mode based on a
+ * pthread mutex when it isn't.
+ *
+ * __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4 was introduced in GCC 4.3 and Clang 3.3,
+ * building with older compilers will result in the compat layer always being
+ * used on x86-32.
+ */
+#ifndef __GCC_HAVE_SYNC_COMPARE_AND_SWAP_4
+#define URCU_ARCH_X86_NO_CAS 1
+/* For backwards compat */
#include <urcu/arch/x86.h>
#elif (defined(__powerpc64__) || defined(__ppc64__))
#include <urcu/arch/x86.h>
#elif (defined(__powerpc64__) || defined(__ppc64__))
#define _uatomic_dec(addr) (__uatomic_dec((addr), sizeof(*(addr))))
#define _uatomic_dec(addr) (__uatomic_dec((addr), sizeof(*(addr))))
-#if ((CAA_BITS_PER_LONG != 64) && defined(URCU_ARCH_I386))
+#ifdef URCU_ARCH_X86_NO_CAS
/* For backwards compat */
#define CONFIG_RCU_COMPAT_ARCH 1
/* For backwards compat */
#define CONFIG_RCU_COMPAT_ARCH 1
-#if defined(URCU_ARCH_I386)
+#ifdef URCU_ARCH_X86_NO_CAS
#include <stdio.h>
#include <pthread.h>
#include <stdio.h>
#include <pthread.h>