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Re: [Ada] improve layout of RETURN type made for CICO mechanism
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: gcc-patches at gcc dot gnu dot org
- Date: Fri, 27 Jan 2012 10:47:51 +0100
- Subject: Re: [Ada] improve layout of RETURN type made for CICO mechanism
- References: <201104082230.27123.ebotcazou@adacore.com>
> 2011-04-08 Eric Botcazou <ebotcazou@adacore.com>
>
> * gcc-interface/decl.c (gnat_to_gnu_entity) <E_Procedure>: Set minimum
> alignment on fields of the RETURN type built for the Copy-In Copy-Out
> mechanism.
This can be counter-productive, as the RETURN type is bigger and might not fit
in registers anymore. This is visible on both x86-64 and PowerPC.
Tested on i586-suse-linux, applied on the mainline.
2012-01-27 Eric Botcazou <ebotcazou@adacore.com>
* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Procedure>: Do not set
an alignment on fields of the RETURN type built for the CICO mechanism.
--
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c (revision 183609)
+++ gcc-interface/decl.c (working copy)
@@ -4305,7 +4305,9 @@ gnat_to_gnu_entity (Entity_Id gnat_entit
gnu_return_type = gnu_new_ret_type;
TYPE_NAME (gnu_return_type) = get_identifier ("RETURN");
- /* Set a default alignment to speed up accesses. */
+ /* Set a default alignment to speed up accesses. But we
+ shouldn't increase the size of the structure too much,
+ lest it doesn't fit in return registers anymore. */
TYPE_ALIGN (gnu_return_type)
= get_mode_alignment (ptr_mode);
}
@@ -4314,9 +4316,6 @@ gnat_to_gnu_entity (Entity_Id gnat_entit
= create_field_decl (gnu_param_name, gnu_param_type,
gnu_return_type, NULL_TREE, NULL_TREE,
0, 0);
- /* Set a minimum alignment to speed up accesses. */
- if (DECL_ALIGN (gnu_field) < TYPE_ALIGN (gnu_return_type))
- DECL_ALIGN (gnu_field) = TYPE_ALIGN (gnu_return_type);
Sloc_to_locus (Sloc (gnat_param),
&DECL_SOURCE_LOCATION (gnu_field));
DECL_CHAIN (gnu_field) = gnu_field_list;