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Re: [patch] PR19616, take 2


On Wednesday 26 January 2005 01:16, Steven Bosscher wrote:
> So, new approach: Just do not allow sibcalls for functions with
> one or more addressable function arguments, like below.  I'm
> testing this patch now.

Bootstrapped and tested on x86_64-suse-linux-gnu again.
OK for mainline?

Gr.
Steven

	* 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.


> Index: calls.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/calls.c,v
> retrieving revision 1.377
> diff -u -3 -p -r1.377 calls.c
> --- calls.c	18 Jan 2005 23:06:55 -0000	1.377
> +++ calls.c	26 Jan 2005 00:11:18 -0000
> @@ -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));
> Index: tree-tailcall.c
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree-tailcall.c,v
> retrieving revision 2.34
> diff -u -3 -p -r2.34 tree-tailcall.c
> --- tree-tailcall.c	25 Nov 2004 22:31:09 -0000	2.34
> +++ tree-tailcall.c	26 Jan 2005 00:11:19 -0000
> @@ -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;
>  }
>
> Index: tree.h
> ===================================================================
> RCS file: /cvs/gcc/gcc/gcc/tree.h,v
> retrieving revision 1.679
> diff -u -3 -p -r1.679 tree.h
> --- tree.h	16 Jan 2005 15:28:15 -0000	1.679
> +++ tree.h	26 Jan 2005 00:11:19 -0000
> @@ -824,6 +824,9 @@ extern void tree_operand_check_failed (i
>     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.


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