Avoid atomic_compare_exchange_n if no __GCC_HAVE_SYNC_COMPARE_AND_SWAP_n

* src/atomic_ops/sysdeps/gcc/aarch64.h (AO_GCC_FORCE_HAVE_CAS,
AO_GCC_HAVE_double_SYNC_CAS): Define macro before include generic.h
if __clang__ (workaround).
* src/atomic_ops/sysdeps/gcc/generic-small.h: Regenerate.
* src/atomic_ops/sysdeps/gcc/generic-small.template
(AO_XSIZE_fetch_compare_and_swap, AO_XSIZE_compare_and_swap): Do not
define unless AO_GCC_HAVE_XSIZE_SYNC_CAS.
* src/atomic_ops/sysdeps/gcc/generic.h (AO_GCC_HAVE_char_SYNC_CAS,
AO_GCC_HAVE_short_SYNC_CAS, AO_GCC_HAVE_int_SYNC_CAS,
AO_GCC_HAVE_SYNC_CAS): New internal macro (based on
__GCC_HAVE_SYNC_COMPARE_AND_SWAP_<n> or AO_GCC_FORCE_HAVE_CAS presence).
* src/atomic_ops/sysdeps/gcc/generic.h (AO_GCC_HAVE_double_SYNC_CAS):
New internal macro if AO_HAVE_DOUBLE_PTR_STORAGE.
* src/atomic_ops/sysdeps/gcc/generic.h (AO_double_compare_and_swap):
Check AO_GCC_HAVE_double_SYNC_CAS instead of AO_HAVE_DOUBLE_PTR_STORAGE.

4 files changed, 144 insertions, 96 deletions

diff --git a/src/atomic_ops/sysdeps/gcc/aarch64.h b/src/atomic_ops/sysdeps/gcc/aarch64.h
index d3508a6..9a6ef5a 100644
--- a/src/atomic_ops/sysdeps/gcc/aarch64.h
+++ b/src/atomic_ops/sysdeps/gcc/aarch64.h
@@ -207,4 +207,10 @@
 
 #endif /* !AO_PREFER_BUILTIN_ATOMICS */
 
+#if defined(__clang__)
+  /* As of clang-3.6/arm64, __GCC_HAVE_SYNC_COMPARE_AND_SWAP_n are missing. */
+# define AO_GCC_FORCE_HAVE_CAS
+# define AO_GCC_HAVE_double_SYNC_CAS
+#endif
+
 #include "generic.h"
diff --git a/src/atomic_ops/sysdeps/gcc/generic-small.h b/src/atomic_ops/sysdeps/gcc/generic-small.h
index 72f4a5b..f358f97 100644
--- a/src/atomic_ops/sysdeps/gcc/generic-small.h
+++ b/src/atomic_ops/sysdeps/gcc/generic-small.h
@@ -47,27 +47,29 @@ AO_char_store_release(volatile unsigned/**/char *addr, unsigned/**/char value)
 }
 #define AO_HAVE_char_store_release
 
-AO_INLINE unsigned/**/char
-AO_char_fetch_compare_and_swap(volatile unsigned/**/char *addr,
-                                unsigned/**/char old_val, unsigned/**/char new_val)
-{
-  return __sync_val_compare_and_swap(addr, old_val, new_val
-                                     /* empty protection list */);
-}
-#define AO_HAVE_char_fetch_compare_and_swap
-
-/* TODO: Add CAS _acquire/release/full primitives. */
-
-#ifndef AO_GENERALIZE_ASM_BOOL_CAS
-  AO_INLINE int
-  AO_char_compare_and_swap(volatile unsigned/**/char *addr,
-                            unsigned/**/char old_val, unsigned/**/char new_val)
+#ifdef AO_GCC_HAVE_char_SYNC_CAS
+  AO_INLINE unsigned/**/char
+  AO_char_fetch_compare_and_swap(volatile unsigned/**/char *addr,
+                                  unsigned/**/char old_val, unsigned/**/char new_val)
   {
-    return __sync_bool_compare_and_swap(addr, old_val, new_val
-                                        /* empty protection list */);
+    return __sync_val_compare_and_swap(addr, old_val, new_val
+                                       /* empty protection list */);
   }
-# define AO_HAVE_char_compare_and_swap
-#endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+# define AO_HAVE_char_fetch_compare_and_swap
+
+  /* TODO: Add CAS _acquire/release/full primitives.    */
+
+# ifndef AO_GENERALIZE_ASM_BOOL_CAS
+    AO_INLINE int
+    AO_char_compare_and_swap(volatile unsigned/**/char *addr,
+                              unsigned/**/char old_val, unsigned/**/char new_val)
+    {
+      return __sync_bool_compare_and_swap(addr, old_val, new_val
+                                          /* empty protection list */);
+    }
+#   define AO_HAVE_char_compare_and_swap
+# endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+#endif /* AO_GCC_HAVE_char_SYNC_CAS */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -117,27 +119,29 @@ AO_short_store_release(volatile unsigned/**/short *addr, unsigned/**/short value
 }
 #define AO_HAVE_short_store_release
 
-AO_INLINE unsigned/**/short
-AO_short_fetch_compare_and_swap(volatile unsigned/**/short *addr,
-                                unsigned/**/short old_val, unsigned/**/short new_val)
-{
-  return __sync_val_compare_and_swap(addr, old_val, new_val
-                                     /* empty protection list */);
-}
-#define AO_HAVE_short_fetch_compare_and_swap
-
-/* TODO: Add CAS _acquire/release/full primitives. */
-
-#ifndef AO_GENERALIZE_ASM_BOOL_CAS
-  AO_INLINE int
-  AO_short_compare_and_swap(volatile unsigned/**/short *addr,
-                            unsigned/**/short old_val, unsigned/**/short new_val)
+#ifdef AO_GCC_HAVE_short_SYNC_CAS
+  AO_INLINE unsigned/**/short
+  AO_short_fetch_compare_and_swap(volatile unsigned/**/short *addr,
+                                  unsigned/**/short old_val, unsigned/**/short new_val)
   {
-    return __sync_bool_compare_and_swap(addr, old_val, new_val
-                                        /* empty protection list */);
+    return __sync_val_compare_and_swap(addr, old_val, new_val
+                                       /* empty protection list */);
   }
-# define AO_HAVE_short_compare_and_swap
-#endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+# define AO_HAVE_short_fetch_compare_and_swap
+
+  /* TODO: Add CAS _acquire/release/full primitives.    */
+
+# ifndef AO_GENERALIZE_ASM_BOOL_CAS
+    AO_INLINE int
+    AO_short_compare_and_swap(volatile unsigned/**/short *addr,
+                              unsigned/**/short old_val, unsigned/**/short new_val)
+    {
+      return __sync_bool_compare_and_swap(addr, old_val, new_val
+                                          /* empty protection list */);
+    }
+#   define AO_HAVE_short_compare_and_swap
+# endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+#endif /* AO_GCC_HAVE_short_SYNC_CAS */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -187,27 +191,29 @@ AO_int_store_release(volatile unsigned *addr, unsigned value)
 }
 #define AO_HAVE_int_store_release
 
-AO_INLINE unsigned
-AO_int_fetch_compare_and_swap(volatile unsigned *addr,
-                                unsigned old_val, unsigned new_val)
-{
-  return __sync_val_compare_and_swap(addr, old_val, new_val
-                                     /* empty protection list */);
-}
-#define AO_HAVE_int_fetch_compare_and_swap
-
-/* TODO: Add CAS _acquire/release/full primitives. */
-
-#ifndef AO_GENERALIZE_ASM_BOOL_CAS
-  AO_INLINE int
-  AO_int_compare_and_swap(volatile unsigned *addr,
-                            unsigned old_val, unsigned new_val)
+#ifdef AO_GCC_HAVE_int_SYNC_CAS
+  AO_INLINE unsigned
+  AO_int_fetch_compare_and_swap(volatile unsigned *addr,
+                                  unsigned old_val, unsigned new_val)
   {
-    return __sync_bool_compare_and_swap(addr, old_val, new_val
-                                        /* empty protection list */);
+    return __sync_val_compare_and_swap(addr, old_val, new_val
+                                       /* empty protection list */);
   }
-# define AO_HAVE_int_compare_and_swap
-#endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+# define AO_HAVE_int_fetch_compare_and_swap
+
+  /* TODO: Add CAS _acquire/release/full primitives.    */
+
+# ifndef AO_GENERALIZE_ASM_BOOL_CAS
+    AO_INLINE int
+    AO_int_compare_and_swap(volatile unsigned *addr,
+                              unsigned old_val, unsigned new_val)
+    {
+      return __sync_bool_compare_and_swap(addr, old_val, new_val
+                                          /* empty protection list */);
+    }
+#   define AO_HAVE_int_compare_and_swap
+# endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+#endif /* AO_GCC_HAVE_int_SYNC_CAS */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -257,24 +263,26 @@ AO_store_release(volatile AO_t *addr, AO_t value)
 }
 #define AO_HAVE_store_release
 
-AO_INLINE AO_t
-AO_fetch_compare_and_swap(volatile AO_t *addr,
-                                AO_t old_val, AO_t new_val)
-{
-  return __sync_val_compare_and_swap(addr, old_val, new_val
-                                     /* empty protection list */);
-}
-#define AO_HAVE_fetch_compare_and_swap
-
-/* TODO: Add CAS _acquire/release/full primitives. */
-
-#ifndef AO_GENERALIZE_ASM_BOOL_CAS
-  AO_INLINE int
-  AO_compare_and_swap(volatile AO_t *addr,
-                            AO_t old_val, AO_t new_val)
+#ifdef AO_GCC_HAVE_SYNC_CAS
+  AO_INLINE AO_t
+  AO_fetch_compare_and_swap(volatile AO_t *addr,
+                                  AO_t old_val, AO_t new_val)
   {
-    return __sync_bool_compare_and_swap(addr, old_val, new_val
-                                        /* empty protection list */);
+    return __sync_val_compare_and_swap(addr, old_val, new_val
+                                       /* empty protection list */);
   }
-# define AO_HAVE_compare_and_swap
-#endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+# define AO_HAVE_fetch_compare_and_swap
+
+  /* TODO: Add CAS _acquire/release/full primitives.    */
+
+# ifndef AO_GENERALIZE_ASM_BOOL_CAS
+    AO_INLINE int
+    AO_compare_and_swap(volatile AO_t *addr,
+                              AO_t old_val, AO_t new_val)
+    {
+      return __sync_bool_compare_and_swap(addr, old_val, new_val
+                                          /* empty protection list */);
+    }
+#   define AO_HAVE_compare_and_swap
+# endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+#endif /* AO_GCC_HAVE_SYNC_CAS */
diff --git a/src/atomic_ops/sysdeps/gcc/generic-small.template b/src/atomic_ops/sysdeps/gcc/generic-small.template
index 9685acf..e016488 100644
--- a/src/atomic_ops/sysdeps/gcc/generic-small.template
+++ b/src/atomic_ops/sysdeps/gcc/generic-small.template
@@ -47,24 +47,26 @@ AO_XSIZE_store_release(volatile XCTYPE *addr, XCTYPE value)
 }
 #define AO_HAVE_XSIZE_store_release
 
-AO_INLINE XCTYPE
-AO_XSIZE_fetch_compare_and_swap(volatile XCTYPE *addr,
-                                XCTYPE old_val, XCTYPE new_val)
-{
-  return __sync_val_compare_and_swap(addr, old_val, new_val
-                                     /* empty protection list */);
-}
-#define AO_HAVE_XSIZE_fetch_compare_and_swap
-
-/* TODO: Add CAS _acquire/release/full primitives. */
-
-#ifndef AO_GENERALIZE_ASM_BOOL_CAS
-  AO_INLINE int
-  AO_XSIZE_compare_and_swap(volatile XCTYPE *addr,
-                            XCTYPE old_val, XCTYPE new_val)
+#ifdef AO_GCC_HAVE_XSIZE_SYNC_CAS
+  AO_INLINE XCTYPE
+  AO_XSIZE_fetch_compare_and_swap(volatile XCTYPE *addr,
+                                  XCTYPE old_val, XCTYPE new_val)
   {
-    return __sync_bool_compare_and_swap(addr, old_val, new_val
-                                        /* empty protection list */);
+    return __sync_val_compare_and_swap(addr, old_val, new_val
+                                       /* empty protection list */);
   }
-# define AO_HAVE_XSIZE_compare_and_swap
-#endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+# define AO_HAVE_XSIZE_fetch_compare_and_swap
+
+  /* TODO: Add CAS _acquire/release/full primitives.    */
+
+# ifndef AO_GENERALIZE_ASM_BOOL_CAS
+    AO_INLINE int
+    AO_XSIZE_compare_and_swap(volatile XCTYPE *addr,
+                              XCTYPE old_val, XCTYPE new_val)
+    {
+      return __sync_bool_compare_and_swap(addr, old_val, new_val
+                                          /* empty protection list */);
+    }
+#   define AO_HAVE_XSIZE_compare_and_swap
+# endif /* !AO_GENERALIZE_ASM_BOOL_CAS */
+#endif /* AO_GCC_HAVE_XSIZE_SYNC_CAS */
diff --git a/src/atomic_ops/sysdeps/gcc/generic.h b/src/atomic_ops/sysdeps/gcc/generic.h
index 1df2914..7bb4625 100644
--- a/src/atomic_ops/sysdeps/gcc/generic.h
+++ b/src/atomic_ops/sysdeps/gcc/generic.h
@@ -19,6 +19,29 @@
 /* For the details, see GNU Manual, chapter 6.52 (Built-in functions    */
 /* for memory model aware atomic operations).                           */
 
+#if defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_1) \
+    || defined(AO_GCC_FORCE_HAVE_CAS)
+# define AO_GCC_HAVE_char_SYNC_CAS
+#endif
+
+#if (__SIZEOF_SHORT__ == 2 && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2)) \
+    || defined(AO_GCC_FORCE_HAVE_CAS)
+# define AO_GCC_HAVE_short_SYNC_CAS
+#endif
+
+#if (__SIZEOF_INT__ == 4 && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)) \
+    || (__SIZEOF_INT__ == 8 && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)) \
+    || defined(AO_GCC_FORCE_HAVE_CAS)
+# define AO_GCC_HAVE_int_SYNC_CAS
+#endif
+
+#if (__SIZEOF_SIZE_T__ == 4 && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_4)) \
+    || (__SIZEOF_SIZE_T__ == 8 \
+        && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)) \
+    || defined(AO_GCC_FORCE_HAVE_CAS)
+# define AO_GCC_HAVE_SYNC_CAS
+#endif
+
 #ifdef AO_UNIPROCESSOR
   /* If only a single processor (core) is used, AO_UNIPROCESSOR could   */
   /* be defined by the client to avoid unnecessary memory barrier.      */
@@ -134,6 +157,15 @@
 #   define AO_HAVE_double_store_release
 # endif
 
+# if (__SIZEOF_SIZE_T__ == 4 && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_8)) \
+      || (__SIZEOF_SIZE_T__ == 8 /* half of AO_double_t */ \
+          && defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_16))
+#   define AO_GCC_HAVE_double_SYNC_CAS
+# endif
+
+#endif /* AO_HAVE_DOUBLE_PTR_STORAGE */
+
+#ifdef AO_GCC_HAVE_double_SYNC_CAS
 # ifndef AO_HAVE_double_compare_and_swap
     AO_INLINE int
     AO_double_compare_and_swap(volatile AO_double_t *addr,
@@ -150,4 +182,4 @@
 # endif
 
   /* TODO: Add double CAS _acquire/release/full primitives. */
-#endif /* AO_HAVE_DOUBLE_PTR_STORAGE */
+#endif /* AO_GCC_HAVE_double_SYNC_CAS */