From: Jason Merrill <jason@redhat.com>
To: Jakub Jelinek <jakub@redhat.com>
Cc: gcc-patches@gcc.gnu.org
Subject: Re: [PATCH] c++: Fix up handling of references to anon union members in initializers [PR53932]
Date: Thu, 19 Jan 2023 15:46:35 -0500 [thread overview]
Message-ID: <be0d1824-70c3-7906-1f1b-43e255620059@redhat.com> (raw)
In-Reply-To: <Y8mkUOpknOZyIC1I@tucnak>
On 1/19/23 15:13, Jakub Jelinek wrote:
> Hi!
>
> For anonymous union members we create artificial VAR_DECLs which
> have DECL_VALUE_EXPR for the actual COMPONENT_REF. That works
> just fine inside of functions (including global dynamic constructors),
> because during gimplification such VAR_DECLs are gimplified as
> their DECL_VALUE_EXPR. This is also done during regimplification.
>
> But references to these artificial vars in DECL_INITIAL expressions
> aren't ever replaced by the DECL_VALUE_EXPRs, so we end up either
> with link failures like on the testcase below, or worse ICEs with
> LTO.
>
> The following patch fixes those during cp_fully_fold_init where we
> already walk all the trees (!data->genericize means that
> function rather than cp_fold_function).
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
OK.
> 2023-01-19 Jakub Jelinek <jakub@redhat.com>
>
> PR c++/53932
> * cp-gimplify.cc (cp_fold_r): During cp_fully_fold_init replace
> DECL_ANON_UNION_VAR_P VAR_DECLs with their corresponding
> DECL_VALUE_EXPR.
>
> * g++.dg/init/pr53932.C: New test.
>
> --- gcc/cp/cp-gimplify.cc.jj 2023-01-16 11:52:16.065734330 +0100
> +++ gcc/cp/cp-gimplify.cc 2023-01-19 18:13:54.592661735 +0100
> @@ -1010,6 +1010,16 @@ cp_fold_r (tree *stmt_p, int *walk_subtr
> }
> break;
>
> + case VAR_DECL:
> + /* In initializers replace anon union artificial VAR_DECLs
> + with their DECL_VALUE_EXPRs, as nothing will do it later. */
> + if (DECL_ANON_UNION_VAR_P (stmt) && !data->genericize)
> + {
> + *stmt_p = stmt = unshare_expr (DECL_VALUE_EXPR (stmt));
> + break;
> + }
> + break;
> +
> default:
> break;
> }
> --- gcc/testsuite/g++.dg/init/pr53932.C.jj 2023-01-19 18:22:24.837231192 +0100
> +++ gcc/testsuite/g++.dg/init/pr53932.C 2023-01-19 18:20:51.776586408 +0100
> @@ -0,0 +1,25 @@
> +// PR c++/53932
> +// { dg-do link }
> +
> +static union { int i; };
> +int &r = i;
> +int s = i;
> +int *t = &i;
> +
> +void
> +foo (int **p, int *q)
> +{
> + static int &u = i;
> + static int v = i;
> + static int *w = &i;
> + int &x = i;
> + int y = i;
> + int *z = &i;
> + *p = &i;
> + *q = i;
> +}
> +
> +int
> +main ()
> +{
> +}
>
> Jakub
>
next prev parent reply other threads:[~2023-01-19 20:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-19 20:13 Jakub Jelinek
2023-01-19 20:46 ` Jason Merrill [this message]
2023-01-20 0:11 ` Andrew Pinski
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