runtime, sync: use __atomic intrinsics instead of __sync

    
    GCC has supported the __atomic intrinsics since 4.7.  They are better
    than the __sync intrinsics in that they specify a memory model and,
    more importantly for our purposes, they are reliably implemented
    either in the compiler or in libatomic.
    
    Fixes https://gcc.gnu.org/PR52084
    
    Reviewed-on: https://go-review.googlesource.com/c/160820

From-SVN: r268458

5 files changed, 33 insertions, 95 deletions

diff --git a/libgo/go/runtime/testdata/testprogcgo/lockosthread.c b/libgo/go/runtime/testdata/testprogcgo/lockosthread.c
index b10cc4f..9a8c057 100644
--- a/libgo/go/runtime/testdata/testprogcgo/lockosthread.c
+++ b/libgo/go/runtime/testdata/testprogcgo/lockosthread.c
@@ -9,5 +9,5 @@
 uint32_t threadExited;
 
 void setExited(void *x) {
-	__sync_fetch_and_add(&threadExited, 1);
+	__atomic_add_fetch(&threadExited, 1, __ATOMIC_SEQ_CST);
 }
diff --git a/libgo/go/runtime/testdata/testprogcgo/threadpprof.go b/libgo/go/runtime/testdata/testprogcgo/threadpprof.go
index f803511..28b094f 100644
--- a/libgo/go/runtime/testdata/testprogcgo/threadpprof.go
+++ b/libgo/go/runtime/testdata/testprogcgo/threadpprof.go
@@ -50,13 +50,13 @@ void pprofCgoThreadTraceback(void* parg) {
 	arg->buf[0] = (uintptr_t)(cpuHogThread) + 0x10;
 	arg->buf[1] = (uintptr_t)(cpuHogThread2) + 0x4;
 	arg->buf[2] = 0;
-	__sync_add_and_fetch(&cpuHogThreadCount, 1);
+	__atomic_add_fetch(&cpuHogThreadCount, 1, __ATOMIC_SEQ_CST);
 }
 
 // getCPUHogThreadCount fetches the number of times we've seen cpuHogThread
 // in the traceback.
 int getCPUHogThreadCount() {
-	return __sync_add_and_fetch(&cpuHogThreadCount, 0);
+	return __atomic_load(&cpuHogThreadCount, __ATOMIC_SEQ_CST);
 }
 
 static void* cpuHogDriver(void* arg __attribute__ ((unused))) {
diff --git a/libgo/go/runtime/testdata/testprogcgo/tracebackctxt_c.c b/libgo/go/runtime/testdata/testprogcgo/tracebackctxt_c.c
index f02b7ca..ff6895e 100644
--- a/libgo/go/runtime/testdata/testprogcgo/tracebackctxt_c.c
+++ b/libgo/go/runtime/testdata/testprogcgo/tracebackctxt_c.c
@@ -49,18 +49,18 @@ struct cgoSymbolizerArg {
 static int contextCount;
 
 int getContextCount() {
-	return __sync_add_and_fetch(&contextCount, 0);
+	return __atomic_load_n(&contextCount, __ATOMIC_SEQ_CST);
 }
 
 void tcContext(void* parg) {
 	struct cgoContextArg* arg = (struct cgoContextArg*)(parg);
 	if (arg->context == 0) {
-		arg->context = __sync_add_and_fetch(&contextCount, 1);
+		arg->context = __atomic_add_fetch(&contextCount, 1, __ATOMIC_SEQ_CST);
 	} else {
-		if (arg->context != __sync_add_and_fetch(&contextCount, 0)) {
+		if (arg->context != __atomic_load_n(&contextCount, __ATOMIC_SEQ_CST))
 			abort();
 		}
-		__sync_sub_and_fetch(&contextCount, 1);
+		__atomic_sub_fetch(&contextCount, 1, __ATOMIC_SEQ_CST);
 	}
 }
 
diff --git a/libgo/go/sync/atomic/atomic.c b/libgo/go/sync/atomic/atomic.c
index 6cc730f..25e439d 100644
--- a/libgo/go/sync/atomic/atomic.c
+++ b/libgo/go/sync/atomic/atomic.c
@@ -69,7 +69,8 @@ _Bool CompareAndSwapInt32 (int32_t *, int32_t, int32_t)
 _Bool
 CompareAndSwapInt32 (int32_t *val, int32_t old, int32_t new)
 {
-  return __sync_bool_compare_and_swap (val, old, new);
+  return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST,
+				      __ATOMIC_RELAXED);
 }
 
 _Bool CompareAndSwapInt64 (int64_t *, int64_t, int64_t)
@@ -81,7 +82,8 @@ CompareAndSwapInt64 (int64_t *val, int64_t old, int64_t new)
 {
   if (((uintptr_t) val & 7) != 0)
     val = NULL;
-  return __sync_bool_compare_and_swap (val, old, new);
+  return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST,
+				      __ATOMIC_RELAXED);
 }
 
 _Bool CompareAndSwapUint32 (uint32_t *, uint32_t, uint32_t)
@@ -91,7 +93,8 @@ _Bool CompareAndSwapUint32 (uint32_t *, uint32_t, uint32_t)
 _Bool
 CompareAndSwapUint32 (uint32_t *val, uint32_t old, uint32_t new)
 {
-  return __sync_bool_compare_and_swap (val, old, new);
+  return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST,
+				      __ATOMIC_RELAXED);
 }
 
 _Bool CompareAndSwapUint64 (uint64_t *, uint64_t, uint64_t)
@@ -103,7 +106,8 @@ CompareAndSwapUint64 (uint64_t *val, uint64_t old, uint64_t new)
 {
   if (((uintptr_t) val & 7) != 0)
     val = NULL;
-  return __sync_bool_compare_and_swap (val, old, new);
+  return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST,
+				      __ATOMIC_RELAXED);
 }
 
 _Bool CompareAndSwapUintptr (uintptr_t *, uintptr_t, uintptr_t)
@@ -113,7 +117,8 @@ _Bool CompareAndSwapUintptr (uintptr_t *, uintptr_t, uintptr_t)
 _Bool
 CompareAndSwapUintptr (uintptr_t *val, uintptr_t old, uintptr_t new)
 {
-  return __sync_bool_compare_and_swap (val, old, new);
+  return __atomic_compare_exchange_n (val, &old, new, true, __ATOMIC_SEQ_CST,
+				      __ATOMIC_RELAXED);
 }
 
 int32_t AddInt32 (int32_t *, int32_t)
@@ -123,7 +128,7 @@ int32_t AddInt32 (int32_t *, int32_t)
 int32_t
 AddInt32 (int32_t *val, int32_t delta)
 {
-  return __sync_add_and_fetch (val, delta);
+  return __atomic_add_fetch (val, delta, __ATOMIC_SEQ_CST);
 }
 
 uint32_t AddUint32 (uint32_t *, uint32_t)
@@ -133,7 +138,7 @@ uint32_t AddUint32 (uint32_t *, uint32_t)
 uint32_t
 AddUint32 (uint32_t *val, uint32_t delta)
 {
-  return __sync_add_and_fetch (val, delta);
+  return __atomic_add_fetch (val, delta, __ATOMIC_SEQ_CST);
 }
 
 int64_t AddInt64 (int64_t *, int64_t)
@@ -145,7 +150,7 @@ AddInt64 (int64_t *val, int64_t delta)
 {
   if (((uintptr_t) val & 7) != 0)
     val = NULL;
-  return __sync_add_and_fetch (val, delta);
+  return __atomic_add_fetch (val, delta, __ATOMIC_SEQ_CST);
 }
 
 uint64_t AddUint64 (uint64_t *, uint64_t)
@@ -157,7 +162,7 @@ AddUint64 (uint64_t *val, uint64_t delta)
 {
   if (((uintptr_t) val & 7) != 0)
     val = NULL;
-  return __sync_add_and_fetch (val, delta);
+  return __atomic_add_fetch (val, delta, __ATOMIC_SEQ_CST);
 }
 
 uintptr_t AddUintptr (uintptr_t *, uintptr_t)
@@ -167,7 +172,7 @@ uintptr_t AddUintptr (uintptr_t *, uintptr_t)
 uintptr_t
 AddUintptr (uintptr_t *val, uintptr_t delta)
 {
-  return __sync_add_and_fetch (val, delta);
+  return __atomic_add_fetch (val, delta, __ATOMIC_SEQ_CST);
 }
 
 int32_t LoadInt32 (int32_t *addr)
@@ -177,12 +182,7 @@ int32_t LoadInt32 (int32_t *addr)
 int32_t
 LoadInt32 (int32_t *addr)
 {
-  int32_t v;
-
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, v))
-    v = *addr;
-  return v;
+  return __atomic_load_n (addr, __ATOMIC_SEQ_CST);
 }
 
 int64_t LoadInt64 (int64_t *addr)
@@ -192,14 +192,9 @@ int64_t LoadInt64 (int64_t *addr)
 int64_t
 LoadInt64 (int64_t *addr)
 {
-  int64_t v;
-
   if (((uintptr_t) addr & 7) != 0)
     panicmem ();
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, v))
-    v = *addr;
-  return v;
+  return __atomic_load_n (addr, __ATOMIC_SEQ_CST);
 }
 
 uint32_t LoadUint32 (uint32_t *addr)
@@ -209,12 +204,7 @@ uint32_t LoadUint32 (uint32_t *addr)
 uint32_t
 LoadUint32 (uint32_t *addr)
 {
-  uint32_t v;
-
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, v))
-    v = *addr;
-  return v;
+  return __atomic_load_n (addr, __ATOMIC_SEQ_CST);
 }
 
 uint64_t LoadUint64 (uint64_t *addr)
@@ -224,14 +214,9 @@ uint64_t LoadUint64 (uint64_t *addr)
 uint64_t
 LoadUint64 (uint64_t *addr)
 {
-  uint64_t v;
-
   if (((uintptr_t) addr & 7) != 0)
     panicmem ();
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, v))
-    v = *addr;
-  return v;
+  return __atomic_load_n (addr, __ATOMIC_SEQ_CST);
 }
 
 uintptr_t LoadUintptr (uintptr_t *addr)
@@ -241,12 +226,7 @@ uintptr_t LoadUintptr (uintptr_t *addr)
 uintptr_t
 LoadUintptr (uintptr_t *addr)
 {
-  uintptr_t v;
-
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, v))
-    v = *addr;
-  return v;
+  return __atomic_load_n (addr, __ATOMIC_SEQ_CST);
 }
 
 void *LoadPointer (void **addr)
@@ -256,12 +236,7 @@ void *LoadPointer (void **addr)
 void *
 LoadPointer (void **addr)
 {
-  void *v;
-
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, v))
-    v = *addr;
-  return v;
+  return __atomic_load_n (addr, __ATOMIC_SEQ_CST);
 }
 
 void StoreInt32 (int32_t *addr, int32_t val)
@@ -271,11 +246,7 @@ void StoreInt32 (int32_t *addr, int32_t val)
 void
 StoreInt32 (int32_t *addr, int32_t val)
 {
-  int32_t v;
-
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, val))
-    v = *addr;
+  __atomic_store_n (addr, val, __ATOMIC_SEQ_CST);
 }
 
 void StoreInt64 (int64_t *addr, int64_t val)
@@ -285,13 +256,9 @@ void StoreInt64 (int64_t *addr, int64_t val)
 void
 StoreInt64 (int64_t *addr, int64_t val)
 {
-  int64_t v;
-
   if (((uintptr_t) addr & 7) != 0)
     panicmem ();
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, val))
-    v = *addr;
+  __atomic_store_n (addr, val, __ATOMIC_SEQ_CST);
 }
 
 void StoreUint32 (uint32_t *addr, uint32_t val)
@@ -301,11 +268,7 @@ void StoreUint32 (uint32_t *addr, uint32_t val)
 void
 StoreUint32 (uint32_t *addr, uint32_t val)
 {
-  uint32_t v;
-
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, val))
-    v = *addr;
+  __atomic_store_n (addr, val, __ATOMIC_SEQ_CST);
 }
 
 void StoreUint64 (uint64_t *addr, uint64_t val)
@@ -315,13 +278,9 @@ void StoreUint64 (uint64_t *addr, uint64_t val)
 void
 StoreUint64 (uint64_t *addr, uint64_t val)
 {
-  uint64_t v;
-
   if (((uintptr_t) addr & 7) != 0)
     panicmem ();
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, val))
-    v = *addr;
+  __atomic_store_n (addr, val, __ATOMIC_SEQ_CST);
 }
 
 void StoreUintptr (uintptr_t *addr, uintptr_t val)
@@ -331,9 +290,5 @@ void StoreUintptr (uintptr_t *addr, uintptr_t val)
 void
 StoreUintptr (uintptr_t *addr, uintptr_t val)
 {
-  uintptr_t v;
-
-  v = *addr;
-  while (! __sync_bool_compare_and_swap (addr, v, val))
-    v = *addr;
+  __atomic_store_n (addr, val, __ATOMIC_SEQ_CST);
 }
diff --git a/libgo/go/sync/cas.c b/libgo/go/sync/cas.c
deleted file mode 100644
index 7571c64..0000000
--- a/libgo/go/sync/cas.c
+++ /dev/null
@@ -1,17 +0,0 @@
-/* cas.c -- implement sync.cas for Go.
-
-   Copyright 2009 The Go Authors. All rights reserved.
-   Use of this source code is governed by a BSD-style
-   license that can be found in the LICENSE file.  */
-
-#include <stdint.h>
-
-#include "runtime.h"
-
-_Bool cas (int32_t *, int32_t, int32_t) __asm__ (GOSYM_PREFIX "libgo_sync.sync.cas");
-
-_Bool
-cas (int32_t *ptr, int32_t old, int32_t new)
-{
-  return __sync_bool_compare_and_swap (ptr, old, new);
-}