From: Eric Botcazou <ebotcazou@adacore.com>
To: Richard Biener <richard.guenther@gmail.com>
Cc: gcc-patches@gcc.gnu.org, Jan Hubicka <hubicka@ucw.cz>
Subject: Re: Add VIEW_CONVERT_EXPR to operand_equal_p
Date: Wed, 04 Nov 2015 08:51:00 -0000 [thread overview]
Message-ID: <2270331.u4G6gq9JGs@polaris> (raw)
In-Reply-To: <CAFiYyc3WuxWAS+s3FjB+BGz1bXhxAxM88S-Fj+Gsn0T6DOS6Mg@mail.gmail.com>
[-- Attachment #1: Type: text/plain, Size: 2697 bytes --]
> Ah - tree_ssa_useless_type_conversion and callers, during gimplification.
> I'd like to get rid of it but maybe simply delete the VIEW_CONVERT_EXPR
> case from it for now (and return true unconditionally for NON_LVALUE_EXPR).
>
> Index: gcc/tree-ssa.c
> ===================================================================
> --- gcc/tree-ssa.c (revision 229517)
> +++ gcc/tree-ssa.c (working copy)
> @@ -1142,13 +1161,16 @@ delete_tree_ssa (struct function *fn)
> bool
> tree_ssa_useless_type_conversion (tree expr)
> {
> + /* Not strictly a conversion but this function is used to strip
> + useless stuff from trees returned from GENERIC folding. */
> + if (TREE_CODE (expr) == NON_LVALUE_EXPR)
> + return true;
> +
> /* If we have an assignment that merely uses a NOP_EXPR to change
> the top of the RHS to the type of the LHS and the type conversion
> is "safe", then strip away the type conversion so that we can
> enter LHS = RHS into the const_and_copies table. */
> - if (CONVERT_EXPR_P (expr)
> - || TREE_CODE (expr) == VIEW_CONVERT_EXPR
> - || TREE_CODE (expr) == NON_LVALUE_EXPR)
> + if (CONVERT_EXPR_P (expr))
> return useless_type_conversion_p
> (TREE_TYPE (expr),
> TREE_TYPE (TREE_OPERAND (expr, 0)));
The patch introduces GIMPLE checking failures:
FAIL: c52103m
FAIL: c52103r
FAIL: c52104m
FAIL: c52104r
of the form:
slice9.adb: In function 'Slice9':
slice9.adb:1:1: error: conversion of an SSA_NAME on the left hand side
VIEW_CONVERT_EXPR<character[D.4195:iftmp.10]>("ABCDE");
D.4379 = &VIEW_CONVERT_EXPR<character[D.4195:iftmp.10]>("ABCDE")[D.4378 ...]
{lb: D.4195 sz: 1};
if (TREE_CODE (expr) == VIEW_CONVERT_EXPR)
{
/* For VIEW_CONVERT_EXPRs which are allowed here too, we only check
that their operand is not an SSA name or an invariant when
requiring an lvalue (this usually means there is a SRA or IPA-SRA
bug). Otherwise there is nothing to verify, gross mismatches at
most invoke undefined behavior. */
if (require_lvalue
&& (TREE_CODE (op) == SSA_NAME
|| is_gimple_min_invariant (op)))
{
error ("conversion of an SSA_NAME on the left hand side");
debug_generic_stmt (expr);
return true;
}
else if (TREE_CODE (op) == SSA_NAME
&& TYPE_SIZE (TREE_TYPE (expr)) != TYPE_SIZE (TREE_TYPE (op)))
{
error ("conversion of register to a different size");
debug_generic_stmt (expr);
return true;
}
else if (!handled_component_p (op))
return false;
}
It's related to dynamic slicing (reduced testcase attached).
* gnat.dg/slice9.adb: New test.
--
Eric Botcazou
[-- Attachment #2: slice9.adb --]
[-- Type: text/x-adasrc, Size: 297 bytes --]
-- { dg-do compile }
procedure Slice9 is
function Ident (I : Integer) return Integer is
begin
return I;
end;
subtype S is String (Ident(5)..Ident(9));
Dest : S;
Src : String (Ident(1)..Ident(5)) := "ABCDE";
begin
Dest (Ident(5)..Ident(7)) := Src (Ident(1)..Ident(3));
end;
next prev parent reply other threads:[~2015-11-04 8:51 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 [this message]
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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