From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 60534 invoked by alias); 8 Oct 2015 05:00:28 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Received: (qmail 60188 invoked by uid 89); 8 Oct 2015 05:00:27 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.1 required=5.0 tests=AWL,BAYES_00,FREEMAIL_ENVFROM_END_DIGIT,FREEMAIL_FROM,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-pa0-f41.google.com Received: from mail-pa0-f41.google.com (HELO mail-pa0-f41.google.com) (209.85.220.41) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-GCM-SHA256 encrypted) ESMTPS; Thu, 08 Oct 2015 05:00:25 +0000 Received: by pabve7 with SMTP id ve7so1904348pab.2 for ; Wed, 07 Oct 2015 22:00:23 -0700 (PDT) X-Received: by 10.66.136.102 with SMTP id pz6mr5774156pab.52.1444280423170; Wed, 07 Oct 2015 22:00:23 -0700 (PDT) Received: from bigtime.com ([1.144.5.178]) by smtp.gmail.com with ESMTPSA id a17sm42581270pbu.55.2015.10.07.22.00.21 for (version=TLSv1/SSLv3 cipher=OTHER); Wed, 07 Oct 2015 22:00:22 -0700 (PDT) From: Richard Henderson To: gcc-patches@gcc.gnu.org Subject: [PATCH 1/9] Change default of non-overlapping address space conversion Date: Thu, 08 Oct 2015 05:00:00 -0000 Message-Id: <1444280375-20866-2-git-send-email-rth@redhat.com> In-Reply-To: <1444280375-20866-1-git-send-email-rth@redhat.com> References: <1444280375-20866-1-git-send-email-rth@redhat.com> X-IsSubscribed: yes X-SW-Source: 2015-10/txt/msg00773.txt.bz2 The current default of making all undefined coversions being set to null is not useful. It has caused all users to lie and say that spaces are subsets when they are not, just so that they can override the conversion. * expr.c (expand_expr_real_2): Use convert_modes on disjoint address spaces. --- gcc/expr.c | 30 ++++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-) diff --git a/gcc/expr.c b/gcc/expr.c index 6498a63..fda2ae0 100644 --- a/gcc/expr.c +++ b/gcc/expr.c @@ -8155,34 +8155,40 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode, case ADDR_SPACE_CONVERT_EXPR: { tree treeop0_type = TREE_TYPE (treeop0); - addr_space_t as_to; - addr_space_t as_from; gcc_assert (POINTER_TYPE_P (type)); gcc_assert (POINTER_TYPE_P (treeop0_type)); - as_to = TYPE_ADDR_SPACE (TREE_TYPE (type)); - as_from = TYPE_ADDR_SPACE (TREE_TYPE (treeop0_type)); + addr_space_t as_to = TYPE_ADDR_SPACE (TREE_TYPE (type)); + addr_space_t as_from = TYPE_ADDR_SPACE (TREE_TYPE (treeop0_type)); /* Conversions between pointers to the same address space should have been implemented via CONVERT_EXPR / NOP_EXPR. */ gcc_assert (as_to != as_from); + op0 = expand_expr (treeop0, NULL_RTX, VOIDmode, modifier); + /* Ask target code to handle conversion between pointers to overlapping address spaces. */ if (targetm.addr_space.subset_p (as_to, as_from) || targetm.addr_space.subset_p (as_from, as_to)) { - op0 = expand_expr (treeop0, NULL_RTX, VOIDmode, modifier); op0 = targetm.addr_space.convert (op0, treeop0_type, type); - gcc_assert (op0); - return op0; } - - /* For disjoint address spaces, converting anything but - a null pointer invokes undefined behaviour. We simply - always return a null pointer here. */ - return CONST0_RTX (mode); + else + { + /* For disjoint address spaces, converting anything but a null + pointer invokes undefined behaviour. We truncate or extend the + value as if we'd converted via integers, which handles 0 as + required, and all others as the programmer likely expects. */ +#ifndef POINTERS_EXTEND_UNSIGNED + const int POINTERS_EXTEND_UNSIGNED = 1; +#endif + op0 = convert_modes (mode, TYPE_MODE (treeop0_type), + op0, POINTERS_EXTEND_UNSIGNED); + } + gcc_assert (op0); + return op0; } case POINTER_PLUS_EXPR: -- 2.4.3