cfgexpand.c (expand_gimple_tailcall): Fix case where we need to create a new basic block.

        * cfgexpand.c (expand_gimple_tailcall): Fix case where we need
        to create a new basic block.

From-SVN: r85029

gcc/ChangeLog

+2004-07-21  Richard Henderson  <rth@redhat.com>
+
+	* cfgexpand.c (expand_gimple_tailcall): Fix case where we need
+	to create a new basic block.
+
 2004-07-22  Joseph S. Myers  <jsm@polyomino.org.uk>
 
 	PR c/15052

gcc/cfgexpand.c

@@ -111,26 +111,41 @@ expand_gimple_cond_expr (basic_block bb, tree stmt)
 }
 
 /* A subroutine of expand_gimple_basic_block.  Expand one CALL_EXPR
-   that has CALL_EXPR_TAILCALL set.  Returns a new basic block if we've
-   terminated the current basic block and created a new one.  */
+   that has CALL_EXPR_TAILCALL set.  Returns non-null if we actually
+   generated a tail call (something that might be denied by the ABI
+   rules governing the call; see calls.c).  */
 
 static basic_block
 expand_gimple_tailcall (basic_block bb, tree stmt)
 {
   rtx last = get_last_insn ();
+  edge e;
+  int probability;
+  gcov_type count;
 
   expand_expr_stmt (stmt);
 
   for (last = NEXT_INSN (last); last; last = NEXT_INSN (last))
-    {
     if (CALL_P (last) && SIBLING_CALL_P (last))
-	{
-	  edge e;
-	  int probability = 0;
-	  gcov_type count = 0;
+      goto found;
 
+  return NULL;
+
+ found:
+  /* ??? Wouldn't it be better to just reset any pending stack adjust?
+     Any instructions emitted here are about to be deleted.  */
   do_pending_stack_adjust ();
+
+  /* Remove any non-eh, non-abnormal edges that don't go to exit.  */
+  /* ??? I.e. the fallthrough edge.  HOWEVER!  If there were to be
+     EH or abnormal edges, we shouldn't have created a tail call in
+     the first place.  So it seems to me we should just be removing
+     all edges here, or redirecting the existing fallthru edge to
+     the exit block.  */
+
   e = bb->succ;
+  probability = 0;
+  count = 0;
   while (e)
     {
       edge next = e->succ_next;
@@ -154,10 +169,9 @@ expand_gimple_tailcall (basic_block bb, tree stmt)
       e = next;
     }
 
-	  /* This is somewhat ugly: the call_expr expander often emits
-	     instructions after the sibcall (to perform the function
-	     return).  These confuse the find_sub_basic_blocks code,
-	     so we need to get rid of these.  */
+  /* This is somewhat ugly: the call_expr expander often emits instructions
+     after the sibcall (to perform the function return).  These confuse the
+     find_sub_basic_blocks code, so we need to get rid of these.  */
   last = NEXT_INSN (last);
   if (!BARRIER_P (last))
     abort ();
@@ -169,19 +183,23 @@ expand_gimple_tailcall (basic_block bb, tree stmt)
 	break;
       delete_insn (NEXT_INSN (last));
     }
+
   e = make_edge (bb, EXIT_BLOCK_PTR, EDGE_ABNORMAL | EDGE_SIBCALL);
   e->probability += probability;
   e->count += count;
   BB_END (bb) = last;
   update_bb_for_insn (bb);
+
   if (NEXT_INSN (last))
+    {
       bb = create_basic_block (NEXT_INSN (last), get_last_insn (), bb);
-	  else
-	    return bb;
-	}
+
+      last = BB_END (bb);
+      if (BARRIER_P (last))
+	BB_END (bb) = PREV_INSN (last);
     }
 
-  return NULL;
+  return bb;
 }
 
 /* Expand basic block BB from GIMPLE trees to RTL.  */