Re: Implement -Wswitch-fallthrough: libgomp

[Marek Polacek]

2016-07-11  Marek Polacek  <pola...@redhat.com>

        PR c/7652
        * libgomp.h (gomp_fallthrough): Define.
        * oacc-init.c (resolve_device): Use gomp_fallthrough.
        * testsuite/libgomp.c++/cancel-parallel-2.C: Add __builtin_fallthrough.
        * testsuite/libgomp.c/cancel-parallel-2.c: Add __builtin_fallthrough.

diff --git gcc/libgomp/libgomp.h gcc/libgomp/libgomp.h
index 7b2671b..c0c5e60 100644
--- gcc/libgomp/libgomp.h
+++ gcc/libgomp/libgomp.h
@@ -1080,6 +1080,12 @@ extern int gomp_test_nest_lock_25 (omp_nest_lock_25_t *) 
__GOMP_NOTHROW;
 # define ialias_call(fn) fn
 #endif
 
+#if __GNUC__ >= 7
+# define gomp_fallthrough() __builtin_fallthrough ()
+#else
+# define gomp_fallthrough()
+#endif
+
 /* Helper function for priority_node_to_task() and
    task_to_priority_node().
 
diff --git gcc/libgomp/oacc-init.c gcc/libgomp/oacc-init.c
index f2325ad..70308fc 100644
--- gcc/libgomp/oacc-init.c
+++ gcc/libgomp/oacc-init.c
@@ -144,6 +144,7 @@ resolve_device (acc_device_t d, bool fail_is_error)
        d = acc_device_not_host;
       }
       /* FALLTHROUGH */
+      gomp_fallthrough ();
 
     case acc_device_not_host:
       /* Find the first available device after acc_device_not_host.  */
diff --git gcc/libgomp/testsuite/libgomp.c++/cancel-parallel-2.C 
gcc/libgomp/testsuite/libgomp.c++/cancel-parallel-2.C
index 23b8caa..f793f8a 100644
--- gcc/libgomp/testsuite/libgomp.c++/cancel-parallel-2.C
+++ gcc/libgomp/testsuite/libgomp.c++/cancel-parallel-2.C
@@ -31,6 +31,7 @@ foo (int *x)
       case 2:
        usleep (1000);
        /* FALLTHRU */
+       __builtin_fallthrough ();
       case 1:;
        #pragma omp cancellation point parallel
        break;
diff --git gcc/libgomp/testsuite/libgomp.c/cancel-parallel-2.c 
gcc/libgomp/testsuite/libgomp.c/cancel-parallel-2.c
index 20adb55..054a96e 100644
--- gcc/libgomp/testsuite/libgomp.c/cancel-parallel-2.c
+++ gcc/libgomp/testsuite/libgomp.c/cancel-parallel-2.c
@@ -27,6 +27,7 @@ foo (int *x)
       case 2:
        usleep (1000);
        /* FALLTHRU */
+       __builtin_fallthrough ();
       case 1:;
        #pragma omp cancellation point parallel
        break;