Re: Implement -Wswitch-fallthrough: libatomic

[Marek Polacek]

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

        PR c/7652
        * libatomic_i.h (libat_fallthrough): New macro.
        * gcas.c (libat_compare_exchange): Use libat_fallthrough.
        * gexch.c (libat_exchange): Likewise.
        * glfree.c (libat_is_lock_free): Likewise.
        * gload.c (libat_load): Likewise.
        * gstore.c (libat_store): Likewise.

diff --git gcc/libatomic/gcas.c gcc/libatomic/gcas.c
index 6a5025d..224df8e 100644
--- gcc/libatomic/gcas.c
+++ gcc/libatomic/gcas.c
@@ -92,8 +92,8 @@ libat_compare_exchange (size_t n, void *mptr, void *eptr, 
void *dptr,
     case 8:            EXACT(8);       goto L16;
     case 16:           EXACT(16);      break;
 
-    case 3: L4:                LARGER(4);      /* FALLTHRU */
-    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */
+    case 3: L4:                LARGER(4);      /* FALLTHRU */ 
libat_fallthrough ();
+    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */ libat_fallthrough ();
     case 9 ... 15: L16:        LARGER(16);     break;
 
     Lsucc:
diff --git gcc/libatomic/gexch.c gcc/libatomic/gexch.c
index fddb794..876ae87 100644
--- gcc/libatomic/gexch.c
+++ gcc/libatomic/gexch.c
@@ -116,8 +116,8 @@ libat_exchange (size_t n, void *mptr, void *vptr, void 
*rptr, int smodel)
     case 8:            EXACT(8);       goto L16;
     case 16:           EXACT(16);      break;
 
-    case 3: L4:                LARGER(4);      /* FALLTHRU */
-    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */
+    case 3: L4:                LARGER(4);      /* FALLTHRU */ 
libat_fallthrough ();
+    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */ libat_fallthrough ();
     case 9 ... 15: L16:        LARGER(16);     break;
 
     Lfinish:
diff --git gcc/libatomic/glfree.c gcc/libatomic/glfree.c
index fd1b3a7..3bb09de 100644
--- gcc/libatomic/glfree.c
+++ gcc/libatomic/glfree.c
@@ -56,8 +56,8 @@ libat_is_lock_free (size_t n, void *ptr)
     case 8:            EXACT(8);       goto L16;
     case 16:           EXACT(16);      break;
 
-    case 3: L4:                LARGER(4);      /* FALLTHRU */
-    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */
+    case 3: L4:                LARGER(4);      /* FALLTHRU */ 
libat_fallthrough ();
+    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */ libat_fallthrough ();
     case 9 ... 15: L16:        LARGER(16);     break;
     }
 
diff --git gcc/libatomic/gload.c gcc/libatomic/gload.c
index 64a0dc5..b4cc61c 100644
--- gcc/libatomic/gload.c
+++ gcc/libatomic/gload.c
@@ -79,8 +79,8 @@ libat_load (size_t n, void *mptr, void *rptr, int smodel)
     case 8:            EXACT(8);       goto L16;
     case 16:           EXACT(16);      break;
 
-    case 3: L4:                LARGER(4);      /* FALLTHRU */
-    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */
+    case 3: L4:                LARGER(4);      /* FALLTHRU */ 
libat_fallthrough ();
+    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */ libat_fallthrough ();
     case 9 ... 15: L16:        LARGER(16);     break;
 
     Lfinish:
diff --git gcc/libatomic/gstore.c gcc/libatomic/gstore.c
index af1d060..90a7430 100644
--- gcc/libatomic/gstore.c
+++ gcc/libatomic/gstore.c
@@ -91,8 +91,8 @@ libat_store (size_t n, void *mptr, void *vptr, int smodel)
     case 8:            EXACT(8);       goto L16;
     case 16:           EXACT(16);      break;
 
-    case 3: L4:                LARGER(4);      /* FALLTHRU */
-    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */
+    case 3: L4:                LARGER(4);      /* FALLTHRU */ 
libat_fallthrough ();
+    case 5 ... 7: L8:  LARGER(8);      /* FALLTHRU */ libat_fallthrough ();
     case 9 ... 15: L16:        LARGER(16);     break;
     }
 
diff --git gcc/libatomic/libatomic_i.h gcc/libatomic/libatomic_i.h
index 9206a8e..0faa103 100644
--- gcc/libatomic/libatomic_i.h
+++ gcc/libatomic/libatomic_i.h
@@ -200,6 +200,12 @@ void libat_unlock_n (void *ptr, size_t n);
 # define DECLARE_1(RET,NAME,ARGS)      RET C2(libat_,NAME) ARGS MAN(NAME)
 #endif
 
+#if __GNUC__ >= 7
+# define libat_fallthrough() __builtin_fallthrough ()
+#else
+# define libat_fallthrough()
+#endif
+
 /* Prefix to use when calling internal, possibly ifunc'ed functions.  */
 #if HAVE_IFUNC
 # define local_ ifunc_