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Re: [Ada] Avoid use of secondary stack
- From: Eric Botcazou <ebotcazou at adacore dot com>
- To: gcc-patches at gcc dot gnu dot org
- Cc: Arnaud Charlet <charlet at adacore dot com>, Bob Duff <duff at adacore dot com>
- Date: Thu, 28 May 2015 17:37:08 +0200
- Subject: Re: [Ada] Avoid use of secondary stack
- Authentication-results: sourceware.org; auth=none
- References: <20150528125304 dot GA13459 at adacore dot com>
> This patch avoids the use of the secondary stack, and the corresponding
> cleanup handlers, in many cases. For example, access discriminants no
> longer force functions to return on the secondary stack. This is a speed
> improvement. It is particularly relevant to the Ada.Containers.
It also uncovered a buglet in gigi, fixed thusly, applied on the mainline.
2015-05-28 Eric Botcazou <ebotcazou@adacore.com>
* gcc-interface/decl.c (gnat_to_gnu_entity) <E_Subprogram_Type>: Do
not error out on a return type which has a size that overflows if the
return is done by invisible reference.
--
Eric Botcazou
Index: gcc-interface/decl.c
===================================================================
--- gcc-interface/decl.c (revision 223834)
+++ gcc-interface/decl.c (working copy)
@@ -4224,7 +4224,8 @@ gnat_to_gnu_entity (Entity_Id gnat_entit
/* If the return type has a size that overflows, we cannot have
a function that returns that type. This usage doesn't make
sense anyway, so give an error here. */
- if (TYPE_SIZE_UNIT (gnu_return_type)
+ if (!return_by_invisi_ref_p
+ && TYPE_SIZE_UNIT (gnu_return_type)
&& TREE_CODE (TYPE_SIZE_UNIT (gnu_return_type)) == INTEGER_CST
&& !valid_constant_size_p (TYPE_SIZE_UNIT (gnu_return_type)))
{