This is the mail archive of the
gcc-patches@gcc.gnu.org
mailing list for the GCC project.
Re: [C++ PATCH] Fix ICE in cxx_eval_vec_init_1 (PR c++/84558)
- From: Jason Merrill <jason at redhat dot com>
- To: Jakub Jelinek <jakub at redhat dot com>
- Cc: Nathan Sidwell <nathan at acm dot org>, gcc-patches List <gcc-patches at gcc dot gnu dot org>
- Date: Mon, 26 Feb 2018 16:49:36 -0500
- Subject: Re: [C++ PATCH] Fix ICE in cxx_eval_vec_init_1 (PR c++/84558)
- Authentication-results: sourceware.org; auth=none
- References: <20180226195745.GY5867@tucnak>
OK.
On Mon, Feb 26, 2018 at 2:57 PM, Jakub Jelinek <jakub@redhat.com> wrote:
> Hi!
>
> The PR70001 optimization in cxx_eval_vec_init_1 uses
> initializer_constant_valid_p (eltinit, TREE_TYPE (eltinit))
> which doesn't work if eltinit is NULL. This can happen if
> *non_constant_p is true, but ctx->quiet is true as well (for
> *non_constant_p && !ctx->quiet we break the cycle early).
> No initializer can be treated like a valid initializer and will
> have the advantage that we don't repeat the body for every array element
> and just do it once. The caller will ignore the return value anyway
> when *non_constant_p.
>
> Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> 2018-02-26 Jakub Jelinek <jakub@redhat.com>
>
> PR c++/84558
> * constexpr.c (cxx_eval_vec_init_1): For reuse, treat NULL eltinit like
> a valid constant initializer. Formatting fixes.
>
> * g++.dg/cpp1y/pr84558.C: New test.
>
> --- gcc/cp/constexpr.c.jj 2018-02-26 10:46:02.162316172 +0100
> +++ gcc/cp/constexpr.c 2018-02-26 14:07:38.705532369 +0100
> @@ -2959,9 +2959,8 @@ cxx_eval_vec_init_1 (const constexpr_ctx
> if (!lvalue_p (init))
> eltinit = move (eltinit);
> eltinit = force_rvalue (eltinit, tf_warning_or_error);
> - eltinit = (cxx_eval_constant_expression
> - (&new_ctx, eltinit, lval,
> - non_constant_p, overflow_p));
> + eltinit = cxx_eval_constant_expression (&new_ctx, eltinit, lval,
> + non_constant_p, overflow_p);
> }
> if (*non_constant_p && !ctx->quiet)
> break;
> @@ -2974,12 +2973,13 @@ cxx_eval_vec_init_1 (const constexpr_ctx
> else
> CONSTRUCTOR_APPEND_ELT (*p, idx, eltinit);
> /* Reuse the result of cxx_eval_constant_expression call
> - from the first iteration to all others if it is a constant
> - initializer that doesn't require relocations. */
> + from the first iteration to all others if it is a constant
> + initializer that doesn't require relocations. */
> if (reuse
> && max > 1
> - && (initializer_constant_valid_p (eltinit, TREE_TYPE (eltinit))
> - == null_pointer_node))
> + && (eltinit == NULL_TREE
> + || (initializer_constant_valid_p (eltinit, TREE_TYPE (eltinit))
> + == null_pointer_node)))
> {
> if (new_ctx.ctor != ctx->ctor)
> eltinit = new_ctx.ctor;
> --- gcc/testsuite/g++.dg/cpp1y/pr84558.C.jj 2018-02-26 14:33:56.575318295 +0100
> +++ gcc/testsuite/g++.dg/cpp1y/pr84558.C 2018-02-26 14:33:33.142318527 +0100
> @@ -0,0 +1,6 @@
> +// PR c++/84558
> +// { dg-do compile { target c++14 } }
> +
> +struct A { static int i; constexpr A () { i = 0; } };
> +struct B { A a[2][3][4]; };
> +B b;
>
> Jakub