From: Richard Biener <richard.guenther@gmail.com>
To: Jan Hubicka <hubicka@ucw.cz>
Cc: Eric Botcazou <ebotcazou@adacore.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: Add VIEW_CONVERT_EXPR to operand_equal_p
Date: Thu, 29 Oct 2015 15:24:00 -0000 [thread overview]
Message-ID: <CAFiYyc1X4cDecZ0monVpxXSQ_ywu9anLRNBN9Ay4xx5_tLXtJw@mail.gmail.com> (raw)
In-Reply-To: <20151029150215.GA34652@kam.mff.cuni.cz>
On Thu, Oct 29, 2015 at 4:02 PM, Jan Hubicka <hubicka@ucw.cz> wrote:
>>
>> IMHO it was always wrong/fragile for backends to look at the actual arguments to
>> decide on the calling convention. The backends should _solely_ rely on
>> gimple_call_fntype and its TYPE_ARG_TYPES here.
>>
>> Of course then there are varargs ... (not sure if we hit this here).
>
> Yep, you have varargs and K&R prototypes, so it can't work this way.
Well, then I suppose we need to compute the ABI upfront when we gimplify
from the orginal args (like we preserve fntype). Having a separate fntype
was really meant to make us preserve the ABI throughout the GIMPLE phase...
>>
>> But yes, the VIEW_CONVERT "stripping" is a bit fragile and I don't remember
>> what exactly we gain from it (when not done on registers).
>
> I guess gain is really limited to Ada - there are very few cases we do VCE otherwise.
> (I think we could do more of them). We can make useless_type_conversion NOP/CONVERT
> only. That in fact makes quite a sense because those are types with gimple operations
> on it. Perhaps also VCE on vectors, but not VCE in general.
>
> Honza
>>
>> But I also don't see where we do the stripping mentioned on memory references.
>> The match.pd pattern doesn't apply to memory, only in the GENERIC path
>> which is guarded with exact type equality. So I can't see where we end up
>> stripping the V_C_E.
>>
>> There is one bogus case still in fold-const.c:
>>
>> case VIEW_CONVERT_EXPR:
>> if (TREE_CODE (op0) == MEM_REF)
>> /* ??? Bogus for aligned types. */
>> return fold_build2_loc (loc, MEM_REF, type,
>> TREE_OPERAND (op0, 0), TREE_OPERAND (op0, 1));
>>
>> return NULL_TREE;
>>
>> that comment is only in my local tree ... (we lose alignment info that is
>> on the original MEM_REF type which may be a smaller one).
>>
>> Richard.
>>
>> > Honza
>> >>
>> >>
>> >> * gnat.dg/discr44.adb: New test.
>> >>
>> >> --
>> >> Eric Botcazou
>> >
>> >> -- { dg-do run }
>> >> -- { dg-options "-gnatws" }
>> >>
>> >> procedure Discr44 is
>> >>
>> >> function Ident (I : Integer) return Integer is
>> >> begin
>> >> return I;
>> >> end;
>> >>
>> >> type Int is range 1 .. 10;
>> >>
>> >> type Str is array (Int range <>) of Character;
>> >>
>> >> type Parent (D1, D2 : Int; B : Boolean) is record
>> >> S : Str (D1 .. D2);
>> >> end record;
>> >>
>> >> type Derived (D : Int) is new Parent (D1 => D, D2 => D, B => False);
>> >>
>> >> X1 : Derived (D => Int (Ident (7)));
>> >>
>> >> begin
>> >> if X1.D /= 7 then
>> >> raise Program_Error;
>> >> end if;
>> >> end;
>> >
next prev parent reply other threads:[~2015-10-29 15:23 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-14 16:29 Jan Hubicka
2015-10-15 8:39 ` Richard Biener
2015-10-15 11:22 ` Eric Botcazou
2015-10-15 19:47 ` Eric Botcazou
2015-10-15 23:24 ` Jan Hubicka
2015-10-16 15:58 ` Eric Botcazou
2015-10-16 21:47 ` Richard Biener
2015-10-17 10:27 ` Eric Botcazou
2015-10-17 15:17 ` Richard Biener
2015-10-17 18:57 ` Jan Hubicka
2015-10-18 12:57 ` Eric Botcazou
2015-10-18 16:37 ` Jan Hubicka
2015-10-18 17:14 ` Richard Biener
2015-10-18 18:45 ` Jan Hubicka
2015-10-19 12:31 ` Richard Biener
2015-10-19 21:01 ` Jan Hubicka
2015-10-19 8:17 ` Eric Botcazou
2015-10-19 7:58 ` Eric Botcazou
2015-10-19 19:46 ` Jan Hubicka
2015-10-20 7:02 ` Eric Botcazou
2015-10-21 22:22 ` Jan Hubicka
2015-10-22 8:52 ` Andreas Schwab
2015-10-28 22:49 ` Eric Botcazou
2015-10-29 4:35 ` Jan Hubicka
2015-10-29 11:31 ` Richard Biener
2015-10-29 11:32 ` Richard Biener
2015-10-29 11:32 ` Richard Biener
2015-11-04 8:51 ` Eric Botcazou
2015-10-29 15:06 ` Jan Hubicka
2015-10-29 15:24 ` Richard Biener [this message]
2015-10-29 15:53 ` Jan Hubicka
2015-10-30 8:57 ` Richard Biener
2015-10-30 15:28 ` Jan Hubicka
2015-11-02 9:55 ` Richard Biener
2015-10-30 9:56 ` Eric Botcazou
2015-10-30 15:19 ` Jan Hubicka
2015-10-31 17:39 ` Eric Botcazou
2015-10-31 17:58 ` Richard Biener
2015-11-03 10:26 ` Eric Botcazou
2015-11-03 11:39 ` Richard Biener
2015-11-02 9:30 ` Andreas Schwab
2015-11-03 8:43 ` Eric Botcazou
2015-11-04 7:23 ` Jan Hubicka
2015-11-04 8:20 ` Eric Botcazou
2015-11-04 16:50 ` Jan Hubicka
2015-11-05 13:49 ` Richard Biener
2015-10-21 4:42 ` Jan Hubicka
2015-10-21 8:54 ` Richard Biener
2015-10-21 11:24 ` Eric Botcazou
2015-10-23 5:22 ` Jan Hubicka
2015-10-23 9:14 ` Richard Biener
2015-10-15 16:59 ` Jan Hubicka
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