One year ago the compiler (gigi) was changed to align the RETURN structure
generated for the Copy-In Copy-Out mechanism:
http://gcc.gnu.org/ml/gcc-patches/2010-04/msg00256.html
This helps to generate better code, especially on 64-bit platforms. But this
is not sufficient in some cases, i.e. when there are integer and fixed-point
types involved. The attached patch improves the layout of the type.
Tested on i586-suse-linux, applied on the mainline.
2011-04-08 Eric Botcazou <ebotca...@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.
--
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c (revision 172166)
+++ gcc-interface/decl.c (working copy)
@@ -4226,6 +4226,9 @@ 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;
