2003-11-19 Andrew Cagney <cagney@redhat.com>

* stack.c (return_command): Handle "void", "legacy" and "unknown
	location" return values separatly.
	* values.c (using_struct_return): Return 0 for a "void" return
	type.  Mention "register_value_being_returned".
	(register_value_being_returned): Mention "using_struct_return".

gdb/ChangeLog

@@ -1,3 +1,11 @@
+2003-11-19  Andrew Cagney  <cagney@redhat.com>
+
+	* stack.c (return_command): Handle "void", "legacy" and "unknown
+	location" return values separatly.
+	* values.c (using_struct_return): Return 0 for a "void" return
+	type.  Mention "register_value_being_returned".
+	(register_value_being_returned): Mention "using_struct_return".
+
 2003-11-19  Daniel Jacobowitz  <drow@mvista.com>
 
 	* dwarf2read.c (offreg, basereg, isderef, frame_base_reg)

gdb/stack.c

@@ -1854,33 +1854,33 @@ return_command (char *retval_exp, int from_tty)
       if (VALUE_LAZY (return_value))
 	value_fetch_lazy (return_value);
 
-      /* Check that this architecture can handle the function's return
+      if (TYPE_CODE (return_type) == TYPE_CODE_VOID)
-         type.  In the case of "struct convention", still do the
+	/* If the return-type is "void", don't try to find the
-         "return", just also warn the user.  */
+           return-value's location.  However, do still evaluate the
-      if (gdbarch_return_value_p (current_gdbarch))
+           return expression so that, even when the expression result
-	{
+           is discarded, side effects such as "return i++" still
-	  if (gdbarch_return_value (current_gdbarch, return_type,
+           occure.  */
-				    NULL, NULL, NULL)
-	      == RETURN_VALUE_STRUCT_CONVENTION)
 	return_value = NULL;
-	}
+      else if (!gdbarch_return_value_p (current_gdbarch)
-      else
+	       && (TYPE_CODE (return_type) == TYPE_CODE_STRUCT
+		   || TYPE_CODE (return_type) == TYPE_CODE_UNION))
 	{
-	  /* NOTE: cagney/2003-10-20: The double check is to ensure
+	  /* NOTE: cagney/2003-10-20: Compatibility hack for legacy
-	     that the STORE_RETURN_VALUE call, further down, is not
+	     code.  Old architectures don't expect STORE_RETURN_VALUE
-	     applied to a struct or union return-value.  It wasn't
+	     to be called with with a small struct that needs to be
-	     allowed previously, so don't start allowing it now.  An
+	     stored in registers.  Don't start doing it now.  */
-	     ABI that uses "register convention" to return small
-	     structures and should implement the "return_value"
-	     architecture method.  */
-	  if (using_struct_return (return_type, 0)
-	      || TYPE_CODE (return_type) == TYPE_CODE_STRUCT
-	      || TYPE_CODE (return_type) == TYPE_CODE_UNION)
-	    return_value = NULL;
-	}
-      if (return_value == NULL)
 	  query_prefix = "\
-The location at which to store the function's return value is unknown.\n";
+A structure or union return type is not supported by this architecture.\n\
+If you continue, the return value that you specified will be ignored.\n";
+	  return_value = NULL;
+	}
+      else if (using_struct_return (return_type, 0))
+	{
+	  query_prefix = "\
+The location at which to store the function's return value is unknown.\n\
+If you continue, the return value that you specified will be ignored.\n";
+	  return_value = NULL;
+	}
     }
 
   /* Does an interactive user really want to do this?  Include

gdb/values.c

@@ -1223,7 +1223,7 @@ register_value_being_returned (struct type *valtype, struct regcache *retbuf)
   struct value *val = allocate_value (valtype);
 
   /* If the function returns void, don't bother fetching the return
-     value.  */
+     value.  See also "using_struct_return".  */
   if (TYPE_CODE (valtype) == TYPE_CODE_VOID)
     return val;
 
@@ -1285,6 +1285,11 @@ using_struct_return (struct type *value_type, int gcc_p)
   if (code == TYPE_CODE_ERROR)
     error ("Function return type unknown.");
 
+  if (code == TYPE_CODE_VOID)
+    /* A void return value is never in memory.  See also corresponding
+       code in "register_value_being_returned".  */
+    return 0;
+
   if (!gdbarch_return_value_p (current_gdbarch))
     {
       /* FIXME: cagney/2003-10-01: The below is dead.  Instead an