On Sat, Jul 9, 2011 at 11:28 PM, H.J. Lu <hongjiu...@intel.com> wrote:
> X32 psABI requires promoting pointers to Pmode when passing/returning
> in registers. OK for trunk?
>
> Thanks.
>
> H.J.
> --
> 2011-07-09 H.J. Lu <hongjiu...@intel.com>
>
> * config/i386/i386.c (ix86_promote_function_mode): New.
> (TARGET_PROMOTE_FUNCTION_MODE): Likewise.
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 04cb07d..c852719 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -7052,6 +7061,23 @@ ix86_function_value (const_tree valtype, const_tree
> fntype_or_decl,
> return ix86_function_value_1 (valtype, fntype_or_decl, orig_mode, mode);
> }
>
> +/* Pointer function arguments and return values are promoted to
> + Pmode. */
> +
> +static enum machine_mode
> +ix86_promote_function_mode (const_tree type, enum machine_mode mode,
> + int *punsignedp, const_tree fntype,
> + int for_return)
> +{
> + if (for_return != 1 && type != NULL_TREE && POINTER_TYPE_P (type))
> + {
> + *punsignedp = POINTERS_EXTEND_UNSIGNED;
> + return Pmode;
> + }
> + return default_promote_function_mode (type, mode, punsignedp, fntype,
> + for_return);
> +}
Please rewrite the condition to:
if (for_return == 1)
/* Do not promote function return values. */
;
else if (type != NULL_TREE && ...)
Also, please add some comments.
Your comment also says that pointer return arguments are promoted to
Pmode. The documentation says that:
FOR_RETURN allows to distinguish the promotion of arguments and
return values. If it is `1', a return value is being promoted and
`TARGET_FUNCTION_VALUE' must perform the same promotions done here.
If it is `2', the returned mode should be that of the register in
which an incoming parameter is copied, or the outgoing result is
computed; then the hook should return the same mode as
`promote_mode', though the signedness may be different.
You bypass promotions when FOR_RETURN is 1.
Uros.
