Fix link fail caused by missing GCC char/short atomic primitives on riscv64

Issue #46 (libatomic_ops).

gcc/riscv requires the client to add -latomic (or -pthread) flag
if char- or short-width compare-and-swap or an arithmetic primitive
is used.  To avoid such a requirement, the corresponding AO primitives
are not provided for now unless AO_PREFER_BUILTIN_ATOMICS is defined.

* src/atomic_ops/sysdeps/gcc/generic-arithm.h: Regenerate.
* src/atomic_ops/sysdeps/gcc/generic-arithm.template
(AO_XSIZE_fetch_and_add_XBAR): Do not define if AO_NO_XSIZE_ARITHM.
* src/atomic_ops/sysdeps/gcc/generic-arithm.template
[!AO_SKIPATOMIC_ANY_and_ANY] (AO_XSIZE_and_XBAR): Likewise.
* src/atomic_ops/sysdeps/gcc/generic-arithm.template
[!AO_SKIPATOMIC_ANY_or_ANY] (AO_XSIZE_or_XBAR): Likewise.
* src/atomic_ops/sysdeps/gcc/generic-arithm.template
[!AO_SKIPATOMIC_ANY_xor_ANY] (AO_XSIZE_xor_XBAR): Likewise.
* src/atomic_ops/sysdeps/gcc/riscv.h (AO_GCC_FORCE_HAVE_CAS): Define
only if __clang__ or AO_PREFER_BUILTIN_ATOMICS; update comment.
* src/atomic_ops/sysdeps/gcc/riscv.h [!__clang__
&& !AO_PREFER_BUILTIN_ATOMICS && !__GCC_HAVE_SYNC_COMPARE_AND_SWAP_1]
(AO_NO_char_ARITHM): Define macro; add comment.
* src/atomic_ops/sysdeps/gcc/riscv.h [!__clang__
&& !AO_PREFER_BUILTIN_ATOMICS && !__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2]
(AO_NO_short_ARITHM): Likewise.
* src/atomic_ops/sysdeps/gcc/riscv.h (AO_NO_char_ARITHM,
AO_NO_short_ARITHM): Undefine after include generic.h.

3 files changed, 84 insertions, 6 deletions

diff --git a/src/atomic_ops/sysdeps/gcc/generic-arithm.h b/src/atomic_ops/sysdeps/gcc/generic-arithm.h
index f7f3878..2688328 100644
--- a/src/atomic_ops/sysdeps/gcc/generic-arithm.h
+++ b/src/atomic_ops/sysdeps/gcc/generic-arithm.h
@@ -15,6 +15,8 @@
  *
  */
 
+#ifndef AO_NO_char_ARITHM
+
 AO_INLINE unsigned/**/char
 AO_char_fetch_and_add(volatile unsigned/**/char *addr, unsigned/**/char incr)
 {
@@ -48,6 +50,8 @@ AO_char_fetch_and_add(volatile unsigned/**/char *addr, unsigned/**/char incr)
   }
 # define AO_HAVE_char_xor
 #endif
+
+#endif /* !AO_NO_char_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -65,6 +69,8 @@ AO_char_fetch_and_add(volatile unsigned/**/char *addr, unsigned/**/char incr)
  *
  */
 
+#ifndef AO_NO_short_ARITHM
+
 AO_INLINE unsigned/**/short
 AO_short_fetch_and_add(volatile unsigned/**/short *addr, unsigned/**/short incr)
 {
@@ -98,6 +104,8 @@ AO_short_fetch_and_add(volatile unsigned/**/short *addr, unsigned/**/short incr)
   }
 # define AO_HAVE_short_xor
 #endif
+
+#endif /* !AO_NO_short_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -115,6 +123,8 @@ AO_short_fetch_and_add(volatile unsigned/**/short *addr, unsigned/**/short incr)
  *
  */
 
+#ifndef AO_NO_int_ARITHM
+
 AO_INLINE unsigned
 AO_int_fetch_and_add(volatile unsigned *addr, unsigned incr)
 {
@@ -148,6 +158,8 @@ AO_int_fetch_and_add(volatile unsigned *addr, unsigned incr)
   }
 # define AO_HAVE_int_xor
 #endif
+
+#endif /* !AO_NO_int_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -165,6 +177,8 @@ AO_int_fetch_and_add(volatile unsigned *addr, unsigned incr)
  *
  */
 
+#ifndef AO_NO_ARITHM
+
 AO_INLINE AO_t
 AO_fetch_and_add(volatile AO_t *addr, AO_t incr)
 {
@@ -198,6 +212,8 @@ AO_fetch_and_add(volatile AO_t *addr, AO_t incr)
   }
 # define AO_HAVE_xor
 #endif
+
+#endif /* !AO_NO_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -215,6 +231,8 @@ AO_fetch_and_add(volatile AO_t *addr, AO_t incr)
  *
  */
 
+#ifndef AO_NO_char_ARITHM
+
 AO_INLINE unsigned/**/char
 AO_char_fetch_and_add_acquire(volatile unsigned/**/char *addr, unsigned/**/char incr)
 {
@@ -248,6 +266,8 @@ AO_char_fetch_and_add_acquire(volatile unsigned/**/char *addr, unsigned/**/char
   }
 # define AO_HAVE_char_xor_acquire
 #endif
+
+#endif /* !AO_NO_char_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -265,6 +285,8 @@ AO_char_fetch_and_add_acquire(volatile unsigned/**/char *addr, unsigned/**/char
  *
  */
 
+#ifndef AO_NO_short_ARITHM
+
 AO_INLINE unsigned/**/short
 AO_short_fetch_and_add_acquire(volatile unsigned/**/short *addr, unsigned/**/short incr)
 {
@@ -298,6 +320,8 @@ AO_short_fetch_and_add_acquire(volatile unsigned/**/short *addr, unsigned/**/sho
   }
 # define AO_HAVE_short_xor_acquire
 #endif
+
+#endif /* !AO_NO_short_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -315,6 +339,8 @@ AO_short_fetch_and_add_acquire(volatile unsigned/**/short *addr, unsigned/**/sho
  *
  */
 
+#ifndef AO_NO_int_ARITHM
+
 AO_INLINE unsigned
 AO_int_fetch_and_add_acquire(volatile unsigned *addr, unsigned incr)
 {
@@ -348,6 +374,8 @@ AO_int_fetch_and_add_acquire(volatile unsigned *addr, unsigned incr)
   }
 # define AO_HAVE_int_xor_acquire
 #endif
+
+#endif /* !AO_NO_int_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -365,6 +393,8 @@ AO_int_fetch_and_add_acquire(volatile unsigned *addr, unsigned incr)
  *
  */
 
+#ifndef AO_NO_ARITHM
+
 AO_INLINE AO_t
 AO_fetch_and_add_acquire(volatile AO_t *addr, AO_t incr)
 {
@@ -398,6 +428,8 @@ AO_fetch_and_add_acquire(volatile AO_t *addr, AO_t incr)
   }
 # define AO_HAVE_xor_acquire
 #endif
+
+#endif /* !AO_NO_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -415,6 +447,8 @@ AO_fetch_and_add_acquire(volatile AO_t *addr, AO_t incr)
  *
  */
 
+#ifndef AO_NO_char_ARITHM
+
 AO_INLINE unsigned/**/char
 AO_char_fetch_and_add_release(volatile unsigned/**/char *addr, unsigned/**/char incr)
 {
@@ -448,6 +482,8 @@ AO_char_fetch_and_add_release(volatile unsigned/**/char *addr, unsigned/**/char
   }
 # define AO_HAVE_char_xor_release
 #endif
+
+#endif /* !AO_NO_char_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -465,6 +501,8 @@ AO_char_fetch_and_add_release(volatile unsigned/**/char *addr, unsigned/**/char
  *
  */
 
+#ifndef AO_NO_short_ARITHM
+
 AO_INLINE unsigned/**/short
 AO_short_fetch_and_add_release(volatile unsigned/**/short *addr, unsigned/**/short incr)
 {
@@ -498,6 +536,8 @@ AO_short_fetch_and_add_release(volatile unsigned/**/short *addr, unsigned/**/sho
   }
 # define AO_HAVE_short_xor_release
 #endif
+
+#endif /* !AO_NO_short_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -515,6 +555,8 @@ AO_short_fetch_and_add_release(volatile unsigned/**/short *addr, unsigned/**/sho
  *
  */
 
+#ifndef AO_NO_int_ARITHM
+
 AO_INLINE unsigned
 AO_int_fetch_and_add_release(volatile unsigned *addr, unsigned incr)
 {
@@ -548,6 +590,8 @@ AO_int_fetch_and_add_release(volatile unsigned *addr, unsigned incr)
   }
 # define AO_HAVE_int_xor_release
 #endif
+
+#endif /* !AO_NO_int_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -565,6 +609,8 @@ AO_int_fetch_and_add_release(volatile unsigned *addr, unsigned incr)
  *
  */
 
+#ifndef AO_NO_ARITHM
+
 AO_INLINE AO_t
 AO_fetch_and_add_release(volatile AO_t *addr, AO_t incr)
 {
@@ -598,6 +644,8 @@ AO_fetch_and_add_release(volatile AO_t *addr, AO_t incr)
   }
 # define AO_HAVE_xor_release
 #endif
+
+#endif /* !AO_NO_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -615,6 +663,8 @@ AO_fetch_and_add_release(volatile AO_t *addr, AO_t incr)
  *
  */
 
+#ifndef AO_NO_char_ARITHM
+
 AO_INLINE unsigned/**/char
 AO_char_fetch_and_add_full(volatile unsigned/**/char *addr, unsigned/**/char incr)
 {
@@ -648,6 +698,8 @@ AO_char_fetch_and_add_full(volatile unsigned/**/char *addr, unsigned/**/char inc
   }
 # define AO_HAVE_char_xor_full
 #endif
+
+#endif /* !AO_NO_char_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -665,6 +717,8 @@ AO_char_fetch_and_add_full(volatile unsigned/**/char *addr, unsigned/**/char inc
  *
  */
 
+#ifndef AO_NO_short_ARITHM
+
 AO_INLINE unsigned/**/short
 AO_short_fetch_and_add_full(volatile unsigned/**/short *addr, unsigned/**/short incr)
 {
@@ -698,6 +752,8 @@ AO_short_fetch_and_add_full(volatile unsigned/**/short *addr, unsigned/**/short
   }
 # define AO_HAVE_short_xor_full
 #endif
+
+#endif /* !AO_NO_short_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -715,6 +771,8 @@ AO_short_fetch_and_add_full(volatile unsigned/**/short *addr, unsigned/**/short
  *
  */
 
+#ifndef AO_NO_int_ARITHM
+
 AO_INLINE unsigned
 AO_int_fetch_and_add_full(volatile unsigned *addr, unsigned incr)
 {
@@ -748,6 +806,8 @@ AO_int_fetch_and_add_full(volatile unsigned *addr, unsigned incr)
   }
 # define AO_HAVE_int_xor_full
 #endif
+
+#endif /* !AO_NO_int_ARITHM */
 /*
  * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
  * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
@@ -765,6 +825,8 @@ AO_int_fetch_and_add_full(volatile unsigned *addr, unsigned incr)
  *
  */
 
+#ifndef AO_NO_ARITHM
+
 AO_INLINE AO_t
 AO_fetch_and_add_full(volatile AO_t *addr, AO_t incr)
 {
@@ -798,3 +860,5 @@ AO_fetch_and_add_full(volatile AO_t *addr, AO_t incr)
   }
 # define AO_HAVE_xor_full
 #endif
+
+#endif /* !AO_NO_ARITHM */
diff --git a/src/atomic_ops/sysdeps/gcc/generic-arithm.template b/src/atomic_ops/sysdeps/gcc/generic-arithm.template
index 41e56bf..916d133 100644
--- a/src/atomic_ops/sysdeps/gcc/generic-arithm.template
+++ b/src/atomic_ops/sysdeps/gcc/generic-arithm.template
@@ -15,6 +15,8 @@
  *
  */
 
+#ifndef AO_NO_XSIZE_ARITHM
+
 AO_INLINE XCTYPE
 AO_XSIZE_fetch_and_add_XBAR(volatile XCTYPE *addr, XCTYPE incr)
 {
@@ -48,3 +50,5 @@ AO_XSIZE_fetch_and_add_XBAR(volatile XCTYPE *addr, XCTYPE incr)
   }
 # define AO_HAVE_XSIZE_xor_XBAR
 #endif
+
+#endif /* !AO_NO_XSIZE_ARITHM */
diff --git a/src/atomic_ops/sysdeps/gcc/riscv.h b/src/atomic_ops/sysdeps/gcc/riscv.h
index ce72816..9a0586a 100644
--- a/src/atomic_ops/sysdeps/gcc/riscv.h
+++ b/src/atomic_ops/sysdeps/gcc/riscv.h
@@ -9,14 +9,24 @@
  * modified is included with the above copyright notice.
  */
 
-/* As of gcc-7.2.0, some __GCC_HAVE_SYNC_COMPARE_AND_SWAP_n are missing. */
-/* The operations are lock-free (even for the types smaller than word).  */
-#define AO_GCC_FORCE_HAVE_CAS
+#if defined(__clang__) || defined(AO_PREFER_BUILTIN_ATOMICS)
+  /* All __GCC_HAVE_SYNC_COMPARE_AND_SWAP_n macros are still missing.   */
+  /* The operations are lock-free even for the types smaller than word. */
+# define AO_GCC_FORCE_HAVE_CAS
+#else
 
-/* While double-word atomic operations are provided by the compiler     */
-/* (which requires -latomic currently), they are not lock-free as       */
-/* riscv itself does not have the double-word atomic operations.        */
+  /* As of gcc-7.5, CAS and arithmetic atomic operations for char and   */
+  /* short are supported by the compiler but require -latomic flag.     */
+# if !defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_1)
+#   define AO_NO_char_ARITHM
+# endif
+# if !defined(__GCC_HAVE_SYNC_COMPARE_AND_SWAP_2)
+#   define AO_NO_short_ARITHM
+# endif
+#endif /* !__clang__ */
 
 #include "generic.h"
 
 #undef AO_GCC_FORCE_HAVE_CAS
+#undef AO_NO_char_ARITHM
+#undef AO_NO_short_ARITHM