use futexes in Mesa on archs with atomics

tested by matthieu@ naddy@ and myself

lib/mesa/Makefile.bsd-wrapper

@@ -1,4 +1,4 @@
-# $OpenBSD: Makefile.bsd-wrapper,v 1.29 2020/01/22 02:49:17 jsg Exp $
+# $OpenBSD: Makefile.bsd-wrapper,v 1.30 2020/02/20 02:55:46 jsg Exp $
 
 .include <bsd.own.mk>
 .include <bsd.xconf.mk>
@@ -31,11 +31,19 @@ VULKAN_DRIVERS=		radeon
 WITH_LLVM=		--enable-llvm
 .endif
 
+.if ${MACHINE_ARCH} == "hppa" || ${MACHINE_ARCH} == "m88k" || \
+    ${MACHINE_ARCH} == "sh"
+WITH_FUTEX=		--disable-futex
+.else
+WITH_FUTEX=		--enable-futex
+.endif
+
 CONFIGURE_ARGS=		--with-dri-drivers=${DRI_DRIVERS} \
 			--with-gallium-drivers=${GALLIUM_DRIVERS} \
 			--with-vulkan-drivers=${VULKAN_DRIVERS} \
 			--disable-silent-rules \
 			${WITH_LLVM} \
+			${WITH_FUTEX} \
 			--disable-glx-tls \
 			--disable-regen-sources \
 			--enable-gles1 --enable-gles2 \

lib/mesa/configure.ac

@@ -1044,6 +1044,16 @@ LIBS="$save_LIBS"
 dnl Check for futex for fast inline simple_mtx_t.
 AC_CHECK_HEADER([linux/futex.h], [DEFINES="$DEFINES -DHAVE_LINUX_FUTEX_H"])
 
+AC_ARG_ENABLE([futex],
+    [AS_HELP_STRING([--disable-futex],
+        [disable futex use @<:@default=enabled@:>@])],
+    [enable_futex="$enableval"],
+    [enable_futex=yes])
+
+if test "x$enable_futex" = xyes; then
+    DEFINES="$DEFINES -DUSE_FUTEX"
+fi
+
 dnl SELinux awareness.
 AC_ARG_ENABLE([selinux],
     [AS_HELP_STRING([--enable-selinux],

lib/mesa/meson.build

@@ -1040,6 +1040,8 @@ foreach h : ['xlocale.h', 'sys/sysctl.h', 'linux/futex.h', 'endian.h', 'dlfcn.h'
   endif
 endforeach
 
+pre_args += '-DUSE_FUTEX'
+
 foreach f : ['strtof', 'mkostemp', 'posix_memalign', 'timespec_get', 'memfd_create', 'random_r', 'flock', 'arc4random_buf']
   if cc.has_function(f)
     pre_args += '-DHAVE_@0@'.format(f.to_upper())

lib/mesa/src/util/simple_mtx.h

@@ -28,7 +28,7 @@
 
 #include "c11/threads.h"
 
-#if defined(__GNUC__) && defined(HAVE_LINUX_FUTEX_H)
+#if defined(__GNUC__) && defined(USE_FUTEX)
 
 /* mtx_t - Fast, simple mutex
  *

lib/mesa/src/util/u_queue.h

@@ -50,7 +50,7 @@ extern "C" {
 #define UTIL_QUEUE_INIT_RESIZE_IF_FULL            (1 << 1)
 #define UTIL_QUEUE_INIT_SET_FULL_THREAD_AFFINITY  (1 << 2)
 
-#if defined(__GNUC__) && defined(HAVE_LINUX_FUTEX_H)
+#if defined(__GNUC__) && defined(USE_FUTEX)
 #define UTIL_QUEUE_FENCE_FUTEX
 #else
 #define UTIL_QUEUE_FENCE_STANDARD