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From: Shawn Landden <shawnlandden@gmail.com>
Date: Thu, 21 Jun 2012 20:34:28 -0700
Subject: configure: 8 byte atomics
fix up configure test to handle lack of 8 byte atomics correctly
as is the case with all ARM targets currently
---
configure | 29 +++++++++++++----------------
configure.in | 19 ++++++++++++++++---
2 files changed, 29 insertions(+), 19 deletions(-)
index a07063d..bfc6df0 100755
--- a/configure.in
+++ b/configure.in
@@ -238,9 +238,22 @@ fi
# Atomic operations
if test "$enable_atomic" != "no"
then
- printf 'checking for atomic operations... '
- AC_TRY_COMPILE([], [__sync_fetch_and_add], [MYGCCATOMIC=yes], [MYGCCATOMIC=no])
- if test "$MYGCCATOMIC" = "yes"
+ printf 'checking for 8 byte atomic operations... '
+ if printf '
+/* Some targets support 4 byte atomics, but not 8 byte atomics,
+ * and will fail at link time if they are used.
+ *
+ * http://gcc.gnu.org/onlinedocs/gcc-4.6.3/gcc/Atomic-Builtins.html
+ * http://gcc.gnu.org/wiki/Atomic
+ */
+#include <stdint.h>
+int
+main ()
+{
+uint64_t n = 0xdeadbeaf;
+__sync_bool_compare_and_swap(&n, 0xdeadbeaf, 0);
+return n;
+}' | $CC -xc -o config.tmp - >/dev/null 2>&1
then
MYCPPFLAGS="$MYCPPFLAGS -D_MYGCCATOMIC"
printf 'yes\n'
--
1.7.9.5
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