Tuple receives indicate whether channel is closed.

From-SVN: r171380

4 files changed, 30 insertions, 15 deletions

diff --git a/libgo/runtime/chan.goc b/libgo/runtime/chan.goc
index da0bbfc..c9de71f 100644
--- a/libgo/runtime/chan.goc
+++ b/libgo/runtime/chan.goc
@@ -12,28 +12,22 @@ typedef struct __go_channel chan;
 
 /* Do a nonblocking channel receive.  */
 
-func chanrecv2(c *chan, val *byte) (pres bool) {
+func chanrecv2(c *chan, val *byte) (received bool) {
 	if (c->element_size > 8) {
-		return __go_receive_nonblocking_big(c, val);
+		return __go_receive_big(c, val, 0);
 	} else {
-		struct __go_receive_nonblocking_small rs;
 		union {
 			char b[8];
 			uint64_t v;
 		} u;
 
-		rs = __go_receive_nonblocking_small (c);
-		if (!rs.__success) {
-			__builtin_memset(val, 0, c->element_size);
-			return 0;
-		}
-		u.v = rs.__val;
+		u.v = __go_receive_small_closed(c, 0, &received);
 #ifndef WORDS_BIGENDIAN
 		__builtin_memcpy(val, u.b, c->element_size);
 #else
 		__builtin_memcpy(val, u.b + 8 - c->element_size,
 				 c->element_size);
 #endif
-		return 1;
+		return received;
 	}
 }
diff --git a/libgo/runtime/channel.h b/libgo/runtime/channel.h
index 5d2f49f..ea10828 100644
--- a/libgo/runtime/channel.h
+++ b/libgo/runtime/channel.h
@@ -112,6 +112,9 @@ extern int __go_receive_nonblocking_acquire (struct __go_channel *);
 
 extern uint64_t __go_receive_small (struct __go_channel *, _Bool);
 
+extern uint64_t __go_receive_small_closed (struct __go_channel *, _Bool,
+					   _Bool *);
+
 extern void __go_receive_release (struct __go_channel *);
 
 struct __go_receive_nonblocking_small
@@ -123,7 +126,7 @@ struct __go_receive_nonblocking_small
 extern struct __go_receive_nonblocking_small
 __go_receive_nonblocking_small (struct __go_channel *);
 
-extern void __go_receive_big (struct __go_channel *, void *, _Bool);
+extern _Bool __go_receive_big (struct __go_channel *, void *, _Bool);
 
 extern _Bool __go_receive_nonblocking_big (struct __go_channel *, void *);
 
diff --git a/libgo/runtime/go-rec-big.c b/libgo/runtime/go-rec-big.c
index 23d6529..a584fe7 100644
--- a/libgo/runtime/go-rec-big.c
+++ b/libgo/runtime/go-rec-big.c
@@ -9,7 +9,7 @@
 #include "go-panic.h"
 #include "channel.h"
 
-void
+_Bool
 __go_receive_big (struct __go_channel *channel, void *val, _Bool for_select)
 {
   size_t alloc_size;
@@ -24,11 +24,13 @@ __go_receive_big (struct __go_channel *channel, void *val, _Bool for_select)
   if (!__go_receive_acquire (channel, for_select))
     {
       __builtin_memset (val, 0, channel->element_size);
-      return;
+      return 0;
     }
 
   offset = channel->next_fetch * alloc_size;
   __builtin_memcpy (val, &channel->data[offset], channel->element_size);
 
   __go_receive_release (channel);
+
+  return 1;
 }
diff --git a/libgo/runtime/go-rec-small.c b/libgo/runtime/go-rec-small.c
index c4dc8b6..87aed3c 100644
--- a/libgo/runtime/go-rec-small.c
+++ b/libgo/runtime/go-rec-small.c
@@ -263,7 +263,8 @@ __go_unlock_and_notify_selects (struct __go_channel *channel)
 /* Receive something 64 bits or smaller on a channel.  */
 
 uint64_t
-__go_receive_small (struct __go_channel *channel, _Bool for_select)
+__go_receive_small_closed (struct __go_channel *channel, _Bool for_select,
+			   _Bool *received)
 {
   uint64_t ret;
 
@@ -273,11 +274,26 @@ __go_receive_small (struct __go_channel *channel, _Bool for_select)
   __go_assert (channel->element_size <= sizeof (uint64_t));
 
   if (!__go_receive_acquire (channel, for_select))
-    return 0;
+    {
+      if (received != NULL)
+	*received = 0;
+      return 0;
+    }
 
   ret = channel->data[channel->next_fetch];
 
   __go_receive_release (channel);
 
+  if (received != NULL)
+    *received = 1;
+
   return ret;
 }
+
+/* Called by the compiler.  */
+
+uint64_t
+__go_receive_small (struct __go_channel *channel, _Bool for_select)
+{
+  return __go_receive_small_closed (channel, for_select, NULL);
+}