[ltt-dev] [PATCH 07/11] add uatomic_gcc.h, use it for default definitions

[pbonzini@redhat.com (Paolo Bonzini)]

From most of the architectures, we can derive the implementation
of xchg and add_return from cmpxchg:

- if cmpxchg is present, use it to implement xchg and add_return;

- if it is not present, implement all three using __sync_* builtins

The hunk in tests/test_uatomic.c is only needed for bisectability
and will be removed later.

Signed-off-by: Paolo Bonzini <pbonzini at redhat.com>
---
 Makefile.am                 |    2 +-
 tests/test_uatomic.c        |    2 +
 urcu/uatomic_arch_ppc.h     |   15 +---
 urcu/uatomic_arch_s390.h    |   15 +---
 urcu/uatomic_arch_sparc64.h |   15 +---
 urcu/uatomic_arch_x86.h     |   26 ++----
 urcu/uatomic_gcc.h          |  221 +++++++++++++++++++++++++++++++++++++++++++
 7 files changed, 239 insertions(+), 57 deletions(-)
 create mode 100644 urcu/uatomic_gcc.h

diff --git a/Makefile.am b/Makefile.am
index 57e9299..d6ee789 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -6,7 +6,7 @@ SUBDIRS = . tests
 
 include_HEADERS = urcu.h $(top_srcdir)/urcu-*.h
 nobase_dist_include_HEADERS = urcu/compiler.h urcu/hlist.h urcu/list.h \
-		urcu/rculist.h urcu/system.h urcu/urcu-futex.h
+		urcu/rculist.h urcu/system.h urcu/urcu-futex.h urcu/uatomic_gcc.h
 nobase_nodist_include_HEADERS = urcu/arch.h urcu/uatomic_arch.h urcu/config.h
 
 EXTRA_DIST = $(top_srcdir)/urcu/arch_*.h $(top_srcdir)/urcu/uatomic_arch_*.h \
diff --git a/tests/test_uatomic.c b/tests/test_uatomic.c
index 68cb6df..c0f36fe 100644
--- a/tests/test_uatomic.c
+++ b/tests/test_uatomic.c
@@ -1,5 +1,7 @@
 #include <stdio.h>
 #include <assert.h>
+
+#define UATOMIC_NO_LINK_ERROR
 #include <urcu/uatomic_arch.h>
 
 #if (defined(__i386__) || defined(__x86_64__))
diff --git a/urcu/uatomic_arch_ppc.h b/urcu/uatomic_arch_ppc.h
index 7106b99..c611c7a 100644
--- a/urcu/uatomic_arch_ppc.h
+++ b/urcu/uatomic_arch_ppc.h
@@ -39,9 +39,6 @@ extern "C" {
 
 #define ILLEGAL_INSTR	".long	0xd00d00"
 
-#define uatomic_set(addr, v)	STORE_SHARED(*(addr), (v))
-#define uatomic_read(addr)	LOAD_SHARED(*(addr))
-
 /*
  * Using a isync as second barrier for exchange to provide acquire semantic.
  * According to uatomic_ops/sysdeps/gcc/powerpc.h, the documentation is "fairly
@@ -217,18 +214,10 @@ unsigned long _uatomic_add_return(void *addr, unsigned long val,
 						  (unsigned long)(v),	\
 						  sizeof(*(addr))))
 
-/* uatomic_sub_return, uatomic_add, uatomic_sub, uatomic_inc, uatomic_dec */
-
-#define uatomic_sub_return(addr, v)	uatomic_add_return((addr), -(v))
-
-#define uatomic_add(addr, v)		(void)uatomic_add_return((addr), (v))
-#define uatomic_sub(addr, v)		(void)uatomic_sub_return((addr), (v))
-
-#define uatomic_inc(addr)		uatomic_add((addr), 1)
-#define uatomic_dec(addr)		uatomic_add((addr), -1)
-
 #ifdef __cplusplus 
 }
 #endif
 
+#include <urcu/uatomic_gcc.h>
+
 #endif /* _URCU_ARCH_UATOMIC_PPC_H */
diff --git a/urcu/uatomic_arch_s390.h b/urcu/uatomic_arch_s390.h
index 6247601..9d4b74e 100644
--- a/urcu/uatomic_arch_s390.h
+++ b/urcu/uatomic_arch_s390.h
@@ -70,9 +70,6 @@ struct __uatomic_dummy {
 };
 #define __hp(x)	((struct __uatomic_dummy *)(x))
 
-#define uatomic_set(addr, v)	STORE_SHARED(*(addr), (v))
-#define uatomic_read(addr)	LOAD_SHARED(*(addr))
-
 /* xchg */
 
 static inline __attribute__((always_inline))
@@ -200,18 +197,10 @@ unsigned long _uatomic_add_return(void *addr, unsigned long val, int len)
 						  (unsigned long)(v),	\
 						  sizeof(*(addr))))
 
-/* uatomic_sub_return, uatomic_add, uatomic_sub, uatomic_inc, uatomic_dec */
-
-#define uatomic_sub_return(addr, v)	uatomic_add_return((addr), -(v))
-
-#define uatomic_add(addr, v)		(void)uatomic_add_return((addr), (v))
-#define uatomic_sub(addr, v)		(void)uatomic_sub_return((addr), (v))
-
-#define uatomic_inc(addr)		uatomic_add((addr), 1)
-#define uatomic_dec(addr)		uatomic_add((addr), -1)
-
 #ifdef __cplusplus 
 }
 #endif
 
+#include <urcu/uatomic_gcc.h>
+
 #endif /* _URCU_UATOMIC_ARCH_S390_H */
diff --git a/urcu/uatomic_arch_sparc64.h b/urcu/uatomic_arch_sparc64.h
index e984986..d21d73c 100644
--- a/urcu/uatomic_arch_sparc64.h
+++ b/urcu/uatomic_arch_sparc64.h
@@ -31,9 +31,6 @@ extern "C" {
 #define BITS_PER_LONG	(__SIZEOF_LONG__ * 8)
 #endif
 
-#define uatomic_set(addr, v)	STORE_SHARED(*(addr), (v))
-#define uatomic_read(addr)	LOAD_SHARED(*(addr))
-
 /* cmpxchg */
 
 static inline __attribute__((always_inline))
@@ -161,18 +158,10 @@ unsigned long _uatomic_add_return(void *addr, unsigned long val, int len)
 						  (unsigned long)(v),	\
 						  sizeof(*(addr))))
 
-/* uatomic_sub_return, uatomic_add, uatomic_sub, uatomic_inc, uatomic_dec */
-
-#define uatomic_sub_return(addr, v)	uatomic_add_return((addr), -(v))
-
-#define uatomic_add(addr, v)		(void)uatomic_add_return((addr), (v))
-#define uatomic_sub(addr, v)		(void)uatomic_sub_return((addr), (v))
-
-#define uatomic_inc(addr)		uatomic_add((addr), 1)
-#define uatomic_dec(addr)		uatomic_add((addr), -1)
-
 #ifdef __cplusplus 
 }
 #endif
 
+#include <urcu/uatomic_gcc.h>
+
 #endif /* _URCU_ARCH_UATOMIC_PPC_H */
diff --git a/urcu/uatomic_arch_x86.h b/urcu/uatomic_arch_x86.h
index 34f5f87..0aadbd5 100644
--- a/urcu/uatomic_arch_x86.h
+++ b/urcu/uatomic_arch_x86.h
@@ -41,7 +41,11 @@ struct __uatomic_dummy {
 #define __hp(x)	((struct __uatomic_dummy *)(x))
 
 #define _uatomic_set(addr, v)	STORE_SHARED(*(addr), (v))
+
+#if 0
+/* Read is atomic even in compat mode */
 #define _uatomic_read(addr)	LOAD_SHARED(*(addr))
+#endif
 
 /* cmpxchg */
 
@@ -168,7 +172,7 @@ unsigned long __uatomic_exchange(void *addr, unsigned long val, int len)
 	((__typeof__(*(addr))) __uatomic_exchange((addr), (unsigned long)(v), \
 						sizeof(*(addr))))
 
-/* uatomic_add_return, uatomic_sub_return */
+/* uatomic_add_return */
 
 static inline __attribute__((always_inline))
 unsigned long __uatomic_add_return(void *addr, unsigned long val,
@@ -233,9 +237,7 @@ unsigned long __uatomic_add_return(void *addr, unsigned long val,
 						  (unsigned long)(v),	\
 						  sizeof(*(addr))))
 
-#define _uatomic_sub_return(addr, v)	_uatomic_add_return((addr), -(v))
-
-/* uatomic_add, uatomic_sub */
+/* uatomic_add */
 
 static inline __attribute__((always_inline))
 void __uatomic_add(void *addr, unsigned long val, int len)
@@ -289,8 +291,6 @@ void __uatomic_add(void *addr, unsigned long val, int len)
 #define _uatomic_add(addr, v)						   \
 	(__uatomic_add((addr), (unsigned long)(v), sizeof(*(addr))))
 
-#define _uatomic_sub(addr, v)	_uatomic_add((addr), -(v))
-
 
 /* uatomic_inc */
 
@@ -441,24 +441,17 @@ extern unsigned long _compat_uatomic_xchg(void *addr,
 						(unsigned long)(v), 	       \
 						sizeof(*(addr))))
 
-#define compat_uatomic_sub_return(addr, v)				       \
-		compat_uatomic_add_return((addr), -(v))
 #define compat_uatomic_add(addr, v)					       \
 		((void)compat_uatomic_add_return((addr), (v)))
-#define compat_uatomic_sub(addr, v)					       \
-		((void)compat_uatomic_sub_return((addr), (v)))
 #define compat_uatomic_inc(addr)					       \
 		(compat_uatomic_add((addr), 1))
 #define compat_uatomic_dec(addr)					       \
-		(compat_uatomic_sub((addr), 1))
+		(compat_uatomic_add((addr), -1))
 
 #else
 #define UATOMIC_COMPAT(insn)	(_uatomic_##insn)
 #endif
 
-/* Read is atomic even in compat mode */
-#define uatomic_read(addr)	_uatomic_read(addr)
-
 #define uatomic_set(addr, v)			\
 		UATOMIC_COMPAT(set(addr, v))
 #define uatomic_cmpxchg(addr, old, _new)	\
@@ -467,10 +460,7 @@ extern unsigned long _compat_uatomic_xchg(void *addr,
 		UATOMIC_COMPAT(xchg(addr, v))
 #define uatomic_add_return(addr, v)		\
 		UATOMIC_COMPAT(add_return(addr, v))
-#define uatomic_sub_return(addr, v)		\
-		UATOMIC_COMPAT(sub_return(addr, v))
 #define uatomic_add(addr, v)	UATOMIC_COMPAT(add(addr, v))
-#define uatomic_sub(addr, v)	UATOMIC_COMPAT(sub(addr, v))
 #define uatomic_inc(addr)	UATOMIC_COMPAT(inc(addr))
 #define uatomic_dec(addr)	UATOMIC_COMPAT(dec(addr))
 
@@ -478,4 +468,6 @@ extern unsigned long _compat_uatomic_xchg(void *addr,
 }
 #endif
 
+#include <urcu/uatomic_gcc.h>
+
 #endif /* _URCU_ARCH_UATOMIC_X86_H */
diff --git a/urcu/uatomic_gcc.h b/urcu/uatomic_gcc.h
new file mode 100644
index 0000000..28f6d71
--- /dev/null
+++ b/urcu/uatomic_gcc.h
@@ -0,0 +1,223 @@
+#ifndef _URCU_UATOMIC_GCC_H
+#define _URCU_UATOMIC_GCC_H
+
+/*
+ * Copyright (c) 1991-1994 by Xerox Corporation.  All rights reserved.
+ * Copyright (c) 1996-1999 by Silicon Graphics.  All rights reserved.
+ * Copyright (c) 1999-2004 Hewlett-Packard Development Company, L.P.
+ * Copyright (c) 2009      Mathieu Desnoyers
+ * Copyright (c) 2010      Paolo Bonzini
+ *
+ * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
+ * OR IMPLIED.  ANY USE IS AT YOUR OWN RISK.
+ *
+ * Permission is hereby granted to use or copy this program
+ * for any purpose,  provided the above notices are retained on all copies.
+ * Permission to modify the code and to distribute modified code is granted,
+ * provided the above notices are retained, and a notice that the code was
+ * modified is included with the above copyright notice.
+ *
+ * Code inspired from libuatomic_ops-1.2, inherited in part from the
+ * Boehm-Demers-Weiser conservative garbage collector.
+ */
+
+#include <urcu/compiler.h>
+#include <urcu/system.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifndef BITS_PER_LONG
+#define BITS_PER_LONG	(__SIZEOF_LONG__ * 8)
+#endif
+
+#ifndef uatomic_set
+#define uatomic_set(addr, v)	STORE_SHARED(*(addr), (v))
+#endif
+
+#ifndef uatomic_read
+#define uatomic_read(addr)	LOAD_SHARED(*(addr))
+#endif
+
+#if !defined __OPTIMIZE__  || defined UATOMIC_NO_LINK_ERROR
+static inline __attribute__((always_inline))
+void _uatomic_link_error()
+{
+#ifdef ILLEGAL_INSTR
+	/* generate an illegal instruction. Cannot catch this with linker tricks
+	 * when optimizations are disabled. */
+	__asm__ __volatile__(ILLEGAL_INSTR);
+#else
+	__builtin_trap ();
+#endif
+}
+#else
+extern void _uatomic_link_error ();
+#endif
+
+/* cmpxchg */
+
+#ifndef uatomic_cmpxchg
+static inline __attribute__((always_inline))
+unsigned long _uatomic_cmpxchg(void *addr, unsigned long old,
+			      unsigned long _new, int len)
+{
+	switch (len) {
+	case 4:
+		return __sync_val_compare_and_swap_4(addr, old, _new);
+#if (BITS_PER_LONG == 64)
+	case 8:
+		return __sync_val_compare_and_swap_8(addr, old, _new);
+#endif
+	}
+	_uatomic_link_error();
+	return 0;
+}
+
+
+#define uatomic_cmpxchg(addr, old, _new)				    \
+	((__typeof__(*(addr))) _uatomic_cmpxchg((addr), (unsigned long)(old),\
+						(unsigned long)(_new), 	    \
+						sizeof(*(addr))))
+
+
+/* uatomic_add_return */
+
+#ifndef uatomic_add_return
+static inline __attribute__((always_inline))
+unsigned long _uatomic_add_return(void *addr, unsigned long val,
+				 int len)
+{
+	switch (len) {
+	case 4:
+		return __sync_add_and_fetch_4(addr, val);
+#if (BITS_PER_LONG == 64)
+	case 8:
+		return __sync_add_and_fetch_8(addr, val);
+#endif
+	}
+	_uatomic_link_error();
+	return 0;
+}
+
+
+#define uatomic_add_return(addr, v)					\
+	((__typeof__(*(addr))) _uatomic_add_return((addr),		\
+						  (unsigned long)(v),	\
+						  sizeof(*(addr))))
+#endif
+
+#else
+
+#ifndef uatomic_add_return
+/* uatomic_add_return */
+
+static inline __attribute__((always_inline))
+unsigned long _uatomic_add_return(void *addr, unsigned long val, int len)
+{
+	switch (len) {
+	case 4:
+	{
+		unsigned int old, oldt;
+
+		oldt = uatomic_read((unsigned int *)addr);
+		do {
+			old = oldt;
+			oldt = _uatomic_cmpxchg(addr, old, old + val, 4);
+		} while (oldt != old);
+
+		return old + val;
+	}
+#if (BITS_PER_LONG == 64)
+	case 8:
+	{
+		unsigned long old, oldt;
+
+		oldt = uatomic_read((unsigned long *)addr);
+		do {
+			old = oldt;
+			oldt = _uatomic_cmpxchg(addr, old, old + val, 8);
+		} while (oldt != old);
+
+		return old + val;
+	}
+#endif
+	}
+	_uatomic_link_error();
+	return 0;
+}
+
+#define uatomic_add_return(addr, v)					\
+	((__typeof__(*(addr))) _uatomic_add_return((addr),		\
+						  (unsigned long)(v),	\
+						  sizeof(*(addr))))
+#endif
+
+#endif
+
+#ifndef uatomic_xchg
+/* xchg */
+
+static inline __attribute__((always_inline))
+unsigned long _uatomic_exchange(void *addr, unsigned long val, int len)
+{
+	switch (len) {
+	case 4:
+	{
+		unsigned int old, oldt;
+
+		oldt = uatomic_read((unsigned int *)addr);
+		do {
+			old = oldt;
+			oldt = _uatomic_cmpxchg(addr, old, val, 4);
+		} while (oldt != old);
+
+		return old;
+	}
+#if (BITS_PER_LONG == 64)
+	case 8:
+	{
+		unsigned long old, oldt;
+
+		oldt = uatomic_read((unsigned long *)addr);
+		do {
+			old = oldt;
+			oldt = _uatomic_cmpxchg(addr, old, val, 8);
+		} while (oldt != old);
+
+		return old;
+	}
+#endif
+	}
+	_uatomic_link_error();
+	return 0;
+}
+
+#define uatomic_xchg(addr, v)						    \
+	((__typeof__(*(addr))) _uatomic_exchange((addr), (unsigned long)(v), \
+						sizeof(*(addr))))
+#endif
+
+/* uatomic_sub_return, uatomic_add, uatomic_sub, uatomic_inc, uatomic_dec */
+
+#ifndef uatomic_add
+#define uatomic_add(addr, v)		(void)uatomic_add_return((addr), (v))
+#endif
+
+#define uatomic_sub_return(addr, v)	uatomic_add_return((addr), -(v))
+#define uatomic_sub(addr, v)		uatomic_add((addr), -(v))
+
+#ifndef uatomic_inc
+#define uatomic_inc(addr)		uatomic_add((addr), 1)
+#endif
+
+#ifndef uatomic_dec
+#define uatomic_dec(addr)		uatomic_add((addr), -1)
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _URCU_UATOMIC_GCC_H */
-- 
1.6.6