From: Jan Hubicka <hubicka@ucw.cz>
To: Richard Biener <richard.guenther@gmail.com>
Cc: Jan Hubicka <hubicka@ucw.cz>,
Eric Botcazou <ebotcazou@adacore.com>,
GCC Patches <gcc-patches@gcc.gnu.org>
Subject: Re: Add VIEW_CONVERT_EXPR to operand_equal_p
Date: Mon, 19 Oct 2015 21:01:00 -0000 [thread overview]
Message-ID: <20151019204731.GA27337@kam.mff.cuni.cz> (raw)
In-Reply-To: <CAFiYyc1-g-gJ1hB2k0045QL+B5fTrgP=EzhPak-7tufdS60brQ@mail.gmail.com>
Richard,
I missed your reply earlier today.
> > Therefore I would say that TYPE_CANONICAL determine mode modulo the fact that
> > incoplete variant of a complete type will have VOIDmode instead of complete
> > type's mode (during non-LTO). That is why I allow mode changes for casts from
> > complete to incomplete.
>
> Incomplete have VOIDmode, right?
Yes
>
> > In longer run I think that every query to useless_type_conversion_p that
> > contains incomplete types is a confused query. useless_type_conversion_p is
> > about operations on the value and there are no operations for incomplete type
> > (and function types). I know that ipa-icf-gimple and the following code in
> > gimplify-stmt checks this frequently:
> > /* The FEs may end up building ADDR_EXPRs early on a decl with
> > an incomplete type. Re-build ADDR_EXPRs in canonical form
> > here. */
> > if (!types_compatible_p (TREE_TYPE (op0), TREE_TYPE (TREE_TYPE (expr))))
> > *expr_p = build_fold_addr_expr (op0);
> > Taking address of incomplete type or functions, naturally, makes sense. We may
> > want to check something else here, like simply
> > TREE_TYPE (op0) != TREE_TYPE (TREE_TYPE (expr))
> > and once ipa-icf is cleanded up start sanity checking in usless_type_conversion
> > that we use it to force equality only on types that do have values.
> >
> > We also can trip it when checking TYPE_METHOD_BASETYPE which may be incomplete.
> > This is in the code checking useless_type_conversion on functions that I think
> > are confused querries anyway - we need the ABI matcher, I am looking into that.
>
> Ok, so given we seem to be fine in practive with TYPE_MODE (type) ==
> TYPE_MODE (TYPE_CANONICAL (type))
Witht the exception of incopmlete variants a type. Then TYPE_CANONICAL may
be complete and !VOIDmode.
But sure, i believe we ought to chase away the calls to useless_type_conversion
when one of types in incomplete.
> (whether that's a but or not ...) I'm fine with re-instantiating the
> mode check for
> aggregate types. Please do that with
>
> Index: gcc/gimple-expr.c
> ===================================================================
> --- gcc/gimple-expr.c (revision 228963)
> +++ gcc/gimple-expr.c (working copy)
> @@ -89,8 +89,7 @@ useless_type_conversion_p (tree outer_ty
>
> /* Changes in machine mode are never useless conversions unless we
> deal with aggregate types in which case we defer to later checks. */
> - if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type)
> - && !AGGREGATE_TYPE_P (inner_type))
> + if (TYPE_MODE (inner_type) != TYPE_MODE (outer_type))
> return false;
OK, that is variant of the patch I had at beggining. I will test it.
>
> /* If both the inner and outer types are integral types, then the
>
> Can we asses equal sizes when modes are non-BLKmode then? Thus
>
> @@ -270,10 +269,9 @@ useless_type_conversion_p (tree outer_ty
> use the types in move operations. */
> else if (AGGREGATE_TYPE_P (inner_type)
> && TREE_CODE (inner_type) == TREE_CODE (outer_type))
> - return (!TYPE_SIZE (outer_type)
> - || (TYPE_SIZE (inner_type)
> - && operand_equal_p (TYPE_SIZE (inner_type),
> - TYPE_SIZE (outer_type), 0)));
> + return (TYPE_MODE (outer_type) != BLKmode
> + || operand_equal_p (TYPE_SIZE (inner_type),
> + TYPE_SIZE (outer_type), 0));
>
> else if (TREE_CODE (inner_type) == OFFSET_TYPE
> && TREE_CODE (outer_type) == OFFSET_TYPE)
>
> ? Hoping for VOIDmode incomplete case.
Don't see why this would be a problem either. I am going to start the testing of this variant.
Honza
>
> Richard.
>
> > Honza
> >>
> >> Richard.
> >>
> >>
> >> >Honza
> >> >>
> >> >> --
> >> >> Eric Botcazou
> >>
next prev parent reply other threads:[~2015-10-19 20:47 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 [this message]
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
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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