score: Simplify CORE_message_queue_Buffer

Merge CORE_message_queue_Buffer structure into
CORE_message_queue_Buffer_control.

Use a zero-length array for the actual message buffer.  This reduces the
structure size on all targets.

Update #4007.

4 files changed, 37 insertions, 41 deletions

diff --git a/cpukit/include/rtems/confdefs/wkspace.h b/cpukit/include/rtems/confdefs/wkspace.h
index 3b464899dc..89d7c21b2a 100644
--- a/cpukit/include/rtems/confdefs/wkspace.h
+++ b/cpukit/include/rtems/confdefs/wkspace.h
@@ -71,7 +71,7 @@
 #define CONFIGURE_MESSAGE_BUFFERS_FOR_QUEUE( _messages, _size ) \
   _Configure_From_workspace( \
     ( _messages ) * ( _Configure_Align_up( _size, sizeof( uintptr_t ) ) \
-        + sizeof( CORE_message_queue_Buffer_control ) ) )
+        + sizeof( CORE_message_queue_Buffer ) ) )
 
 #ifndef CONFIGURE_MESSAGE_BUFFER_MEMORY
   #define CONFIGURE_MESSAGE_BUFFER_MEMORY 0
diff --git a/cpukit/include/rtems/rtems/msgmp.h b/cpukit/include/rtems/rtems/msgmp.h
index 6b08c86971..8638e9748e 100644
--- a/cpukit/include/rtems/rtems/msgmp.h
+++ b/cpukit/include/rtems/rtems/msgmp.h
@@ -71,13 +71,12 @@ typedef struct {
   rtems_option                       option_set;
   Objects_Id                         proxy_id;
   uint32_t                           count;
-  size_t                             size;
-  uint32_t                           pad0;
-  CORE_message_queue_Buffer          Buffer;
+  uint32_t                           size;
+  uint32_t                           buffer[ RTEMS_ZERO_LENGTH_ARRAY ];
 }   Message_queue_MP_Packet;
 
 #define MESSAGE_QUEUE_MP_PACKET_SIZE \
-  offsetof(Message_queue_MP_Packet, Buffer.buffer)
+  offsetof(Message_queue_MP_Packet, buffer)
 
 RTEMS_INLINE_ROUTINE bool _Message_queue_MP_Is_remote( Objects_Id id )
 {
diff --git a/cpukit/include/rtems/score/coremsg.h b/cpukit/include/rtems/score/coremsg.h
index cabf08b0ca..2131fa0765 100644
--- a/cpukit/include/rtems/score/coremsg.h
+++ b/cpukit/include/rtems/score/coremsg.h
@@ -68,37 +68,34 @@ extern "C" {
 typedef struct CORE_message_queue_Control CORE_message_queue_Control;
 
 /**
- *  @brief Data types needed to manipulate the contents of message buffers.
- *
- *  The following defines the data types needed to manipulate
- *  the contents of message buffers.
- *
- *  @note  The buffer field is normally longer than a single uint32_t
- *         but since messages are variable length we just make a ptr to 1.
+ * @brief The structure is used to organize message buffers of a message queue.
  */
 typedef struct {
-  /** This field is the size of this message. */
-  size_t      size;
-  /** This field contains the actual message. */
-  uint32_t    buffer[1];
-} CORE_message_queue_Buffer;
+  /**
+   * @brief This member is used to enqueue the buffer in the pending or free
+   *   buffer queue of a message queue.
+   */
+  Chain_Node Node;
 
-/**
- *  @brief The organization of a message buffer.
- *
- *  The following records define the organization of a message
- *  buffer.
- */
-typedef struct {
-  /** This element allows this structure to be placed on chains. */
-  Chain_Node                 Node;
-  #if defined(RTEMS_SCORE_COREMSG_ENABLE_MESSAGE_PRIORITY)
-    /** This field is the priority of this message. */
-    int                        priority;
-  #endif
-  /** This field points to the contents of the message. */
-  CORE_message_queue_Buffer  Contents;
-}   CORE_message_queue_Buffer_control;
+  /** @brief This member defines the size of this message. */
+  size_t size;
+
+#if defined(RTEMS_SCORE_COREMSG_ENABLE_MESSAGE_PRIORITY)
+  /** @brief This member defines the priority of this message. */
+  int priority;
+#endif
+
+  /**
+   * @brief This member contains the actual message.
+   *
+   * This is a zero-length array since the maximum message size is defined by
+   * the user.  Use a size_t array to make sure that the member offset is at
+   * the structure end.  This enables a more efficient memcpy() on 64-bit
+   * targets and makes it easier to inspect the message buffers with a
+   * debugger.
+   */
+  size_t buffer[ RTEMS_ZERO_LENGTH_ARRAY ];
+} CORE_message_queue_Buffer;
 
 /**
  *  @brief The possible blocking disciplines for a message queue.
diff --git a/cpukit/include/rtems/score/coremsgimpl.h b/cpukit/include/rtems/score/coremsgimpl.h
index 9403fb95fc..cb84bfb207 100644
--- a/cpukit/include/rtems/score/coremsgimpl.h
+++ b/cpukit/include/rtems/score/coremsgimpl.h
@@ -276,7 +276,7 @@ Status_Control _CORE_message_queue_Seize(
  */
 void _CORE_message_queue_Insert_message(
   CORE_message_queue_Control        *the_message_queue,
-  CORE_message_queue_Buffer_control *the_message,
+  CORE_message_queue_Buffer         *the_message,
   const void                        *content_source,
   size_t                             content_size,
   CORE_message_queue_Submit_types    submit_type
@@ -426,12 +426,12 @@ RTEMS_INLINE_ROUTINE void _CORE_message_queue_Copy_buffer (
  * @retval pointer The allocated message buffer.
  * @retval NULL The inactive message buffer chain is empty.
  */
-RTEMS_INLINE_ROUTINE CORE_message_queue_Buffer_control *
+RTEMS_INLINE_ROUTINE CORE_message_queue_Buffer *
 _CORE_message_queue_Allocate_message_buffer (
     CORE_message_queue_Control *the_message_queue
 )
 {
-   return (CORE_message_queue_Buffer_control *)
+   return (CORE_message_queue_Buffer *)
      _Chain_Get_unprotected( &the_message_queue->Inactive_messages );
 }
 
@@ -445,8 +445,8 @@ _CORE_message_queue_Allocate_message_buffer (
  * @param[out] the_message The message to be freed.
  */
 RTEMS_INLINE_ROUTINE void _CORE_message_queue_Free_message_buffer (
-  CORE_message_queue_Control        *the_message_queue,
-  CORE_message_queue_Buffer_control *the_message
+  CORE_message_queue_Control *the_message_queue,
+  CORE_message_queue_Buffer  *the_message
 )
 {
   _Chain_Append_unprotected( &the_message_queue->Inactive_messages, &the_message->Node );
@@ -466,7 +466,7 @@ RTEMS_INLINE_ROUTINE void _CORE_message_queue_Free_message_buffer (
  *       disabled if no API requires it.
  */
 RTEMS_INLINE_ROUTINE int _CORE_message_queue_Get_message_priority (
-  const CORE_message_queue_Buffer_control *the_message
+  const CORE_message_queue_Buffer *the_message
 )
 {
   #if defined(RTEMS_SCORE_COREMSG_ENABLE_MESSAGE_PRIORITY)
@@ -488,11 +488,11 @@ RTEMS_INLINE_ROUTINE int _CORE_message_queue_Get_message_priority (
  * @retval NULL The message queue is empty.
  */
 RTEMS_INLINE_ROUTINE
-  CORE_message_queue_Buffer_control *_CORE_message_queue_Get_pending_message (
+  CORE_message_queue_Buffer *_CORE_message_queue_Get_pending_message (
   CORE_message_queue_Control *the_message_queue
 )
 {
-  return (CORE_message_queue_Buffer_control *)
+  return (CORE_message_queue_Buffer *)
     _Chain_Get_unprotected( &the_message_queue->Pending_messages );
 }