[PATCH libdrm] configure.ac: rework compiler builtin atomic tests

Jonathan Gray jsg at jsg.id.au
Sat Aug 29 00:32:50 PDT 2015

The libdrm autoconf test for atomics uses __sync_val_compare_and_swap with
the address of a function argument which triggers a gcc ICE on sparc64
with the OpenBSD system compiler.

Mark Kettenis pointed out that while other architectures probably spill the
argument onto the stack this is likely not the case on register window
architectures like SPARC and suggested passing a pointer as an argument
instead which avoids the ICE and allows the drm libraries requiring
atomics to build on sparc64 with the autoconf build.

Reported-by: Christian Weisgerber <naddy at openbsd.org>
Signed-off-by: Jonathan Gray <jsg at jsg.id.au>
Reviewed-by: Mark Kettenis <kettenis at openbsd.org>
Reviewed-by: Matthieu Herrb <matthieu at openbsd.org>
 configure.ac | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index f07507b..705ac3e 100644
--- a/configure.ac
+++ b/configure.ac
@@ -210,8 +210,8 @@ AC_CACHE_CHECK([for native atomic primitives], drm_cv_atomic_primitives, [
-	int atomic_add(int i) { return __sync_fetch_and_add (&i, 1); }
-	int atomic_cmpxchg(int i, int j, int k) { return __sync_val_compare_and_swap (&i, j, k); }
+	int atomic_add(int *i) { return __sync_fetch_and_add (i, 1); }
+	int atomic_cmpxchg(int *i, int j, int k) { return __sync_val_compare_and_swap (i, j, k); }
 					  ]],[[]])], [drm_cv_atomic_primitives="Intel"],[])
 	if test "x$drm_cv_atomic_primitives" = "xnone"; then

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