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calls: Further fixes for TYPE_NO_NAMED_ARGS_STDARG_P handling [PR114136]

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On Tue, Feb 27, 2024 at 04:41:32PM +0000, Richard Earnshaw wrote:
> On Arm the PR107453 change is causing all anonymous arguments to be passed on the
> stack, which is incorrect per the ABI.  On a target that uses
> 'pretend_outgoing_vararg_named', why is it correct to set n_named_args to
> zero?  Is it enough to guard both the statements you've added with
> !targetm.calls.pretend_outgoing_args_named?

The TYPE_NO_NAMED_ARGS_STDARG_P functions (C23 fns like void foo (...) {})
have NULL type_arg_types, so the list_length (type_arg_types) isn't done for
it, but it should be handled as if it was non-NULL but list length was 0.

So, for the
  if (type_arg_types != 0)
    n_named_args
      = (list_length (type_arg_types)
         /* Count the struct value address, if it is passed as a parm.  */
         + structure_value_addr_parm);
  else if (TYPE_NO_NAMED_ARGS_STDARG_P (funtype))
    n_named_args = 0;
  else
    /* If we know nothing, treat all args as named.  */
    n_named_args = num_actuals;
case, I think guarding it by any target hooks is wrong, although
I guess it should have been
    n_named_args = structure_value_addr_parm;
instead of
    n_named_args = 0;

For the second
  if (type_arg_types != 0
      && targetm.calls.strict_argument_naming (args_so_far))
    ;
  else if (type_arg_types != 0
           && ! targetm.calls.pretend_outgoing_varargs_named (args_so_far))
    /* Don't include the last named arg.  */
    --n_named_args;
  else if (TYPE_NO_NAMED_ARGS_STDARG_P (funtype))
    n_named_args = 0;
  else
    /* Treat all args as named.  */
    n_named_args = num_actuals;
I think we should treat those as if type_arg_types was non-NULL
with 0 elements in the list, except the --n_named_args would for
!structure_value_addr_parm lead to n_named_args = -1, I think we want
0 for that case.

2024-03-01  Jakub Jelinek  <jakub@redhat.com>

	PR middle-end/114136
	* calls.cc (expand_call): For TYPE_NO_NAMED_ARGS_STDARG_P set
	n_named_args initially before INIT_CUMULATIVE_ARGS to
	structure_value_addr_parm rather than 0, after it don't modify
	it if strict_argument_naming and clear only if
	!pretend_outgoing_varargs_named.
This commit is contained in:
Jakub Jelinek 2024-03-01 15:42:52 +01:00
parent 5b1fb8f8b4
commit b5377928a2
1 changed files with 4 additions and 3 deletions
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7
gcc/calls.cc
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@ -2938,7 +2938,7 @@ expand_call (tree exp, rtx target, int ignore)
/* Count the struct value address, if it is passed as a parm. */
+ structure_value_addr_parm);
else if (TYPE_NO_NAMED_ARGS_STDARG_P (funtype))
n_named_args = 0;
n_named_args = structure_value_addr_parm;
else
/* If we know nothing, treat all args as named. */
n_named_args = num_actuals;
@ -2970,14 +2970,15 @@ expand_call (tree exp, rtx target, int ignore)
we do not have any reliable way to pass unnamed args in
registers, so we must force them into memory. */
if (type_arg_types != 0
if ((type_arg_types != 0 || TYPE_NO_NAMED_ARGS_STDARG_P (funtype))
&& targetm.calls.strict_argument_naming (args_so_far))
;
else if (type_arg_types != 0
&& ! targetm.calls.pretend_outgoing_varargs_named (args_so_far))
/* Don't include the last named arg. */
--n_named_args;
else if (TYPE_NO_NAMED_ARGS_STDARG_P (funtype))
else if (TYPE_NO_NAMED_ARGS_STDARG_P (funtype)
&& ! targetm.calls.pretend_outgoing_varargs_named (args_so_far))
n_named_args = 0;
else
/* Treat all args as named. */