re PR middle-end/19616 (missed tail call)

	PR middle-end/19616
	* tree.h (CALL_EXPR_TAILCALL): Add comment.
	* calls.c (check_sibcall_argument_overlap_1): Revert the change
	to this function from 2004-07-10.
	* tree-tailcall.c (suitable_for_tail_opt_p): Do not consider the
	the current function for tail call optimizations if the address
	of one of it its arguments is taken.

From-SVN: r94265

gcc/ChangeLog

+2005-01-26  Steven Bosscher  <stevenb@suse.de>
+
+	PR middle-end/19616	
+	* tree.h (CALL_EXPR_TAILCALL): Add comment.
+	* calls.c (check_sibcall_argument_overlap_1): Revert the change
+	to this function from 2004-07-10.
+	* tree-tailcall.c (suitable_for_tail_opt_p): Do not consider the
+	the current function for tail call optimizations if the address
+	of one of it its arguments is taken.
+
 2005-01-26  Kazu Hirata  <kazu@cs.umass.edu>
 
 	* cse.c (fold_rtx): Call equiv_constant only when necessary.

gcc/calls.c

@@ -1670,7 +1670,7 @@ check_sibcall_argument_overlap_1 (rtx x)
 	       && GET_CODE (XEXP (XEXP (x, 0), 1)) == CONST_INT)
 	i = INTVAL (XEXP (XEXP (x, 0), 1));
       else
-	return 1;
+	return 0;
 
 #ifdef ARGS_GROW_DOWNWARD
       i = -i - GET_MODE_SIZE (GET_MODE (x));

gcc/tree-tailcall.c

@@ -159,6 +159,8 @@ suitable_for_tail_opt_p (void)
 static bool
 suitable_for_tail_call_opt_p (void)
 {
+  tree param;
+
   /* alloca (until we have stack slot life analysis) inhibits
      sibling call optimizations, but not tail recursion.  */
   if (current_function_calls_alloca)
@@ -176,6 +178,14 @@ suitable_for_tail_call_opt_p (void)
   if (current_function_calls_setjmp)
     return false;
 
+  /* ??? It is OK if the argument of a function is taken in some cases,
+     but not in all cases.  See PR15387 and PR19616.  Revisit for 4.1.  */
+  for (param = DECL_ARGUMENTS (current_function_decl);
+       param;
+       param = TREE_CHAIN (param))
+    if (TREE_ADDRESSABLE (param))
+      return false;
+
   return true;
 }
 

gcc/tree.h

@@ -824,6 +824,9 @@ extern void tree_operand_check_failed (int, enum tree_code,
    had its address taken.  That matters for inline functions.  */
 #define TREE_ADDRESSABLE(NODE) ((NODE)->common.addressable_flag)
 
+/* Set on a CALL_EXPR if the call is in a tail position, ie. just before the
+   exit of a function.  Calls for which this is true are candidates for tail
+   call optimizations.  */
 #define CALL_EXPR_TAILCALL(NODE) (CALL_EXPR_CHECK(NODE)->common.addressable_flag)
 
 /* In a VAR_DECL, nonzero means allocate static storage.