From patchwork Thu Sep 19 13:28:19 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Pierre-Marie de Rodat X-Patchwork-Id: 1164623 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=gcc.gnu.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=gcc-patches-return-509284-incoming=patchwork.ozlabs.org@gcc.gnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=adacore.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=gcc.gnu.org header.i=@gcc.gnu.org header.b="grtR4JSY"; dkim-atps=neutral Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 46YyRf00chz9sPR for ; Thu, 19 Sep 2019 23:31:25 +1000 (AEST) DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:date :from:to:cc:subject:message-id:mime-version:content-type; q=dns; s=default; b=HzCOEePo19uGu+8aVI6q/Bmod6dKC3RuFX9RffzutDJGD/XCU+ +zHNq8zPVjel049fvKcQN5r86lQr56Wq/GP/8BNTRgAosDSpKyAKCZj1vWGPyi3d cA1U80NYuHqRweL4OUTXssqp2qZnzUOlOrj37l1ZieRWDT0TETdC/c7ZY= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:date :from:to:cc:subject:message-id:mime-version:content-type; s= default; bh=WUJ9/NxewQYzNmI26mTnzGp4BYY=; b=grtR4JSYMkM1A1rjaJbS Z3imtJmJnFOkEgl6euAd1vGo98LYqmf21IxuLI5UgFhH1P0FIi7QH/flR0dm/ObB hgszoz+6Errnk8asYj7e+ONBaaqcj28d5yC7648Iyti4R56qAYPRNV6tMUbPy2R9 k8ZTN0XW7C94g9MNRB1lg54= Received: (qmail 3143 invoked by alias); 19 Sep 2019 13:28:38 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org Received: (qmail 2259 invoked by uid 89); 19 Sep 2019 13:28:31 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-11.1 required=5.0 tests=BAYES_00, GIT_PATCH_2, GIT_PATCH_3, SPF_NEUTRAL autolearn=ham version=3.3.1 spammy=exp_util, Exp_Util, exp_utiladb, exp_util.adb X-HELO: eggs.gnu.org Received: from eggs.gnu.org (HELO eggs.gnu.org) (209.51.188.92) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 19 Sep 2019 13:28:29 +0000 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1iAwTy-0001Pv-Lh for gcc-patches@gcc.gnu.org; Thu, 19 Sep 2019 09:28:29 -0400 Received: from rock.gnat.com ([205.232.38.15]:48700) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1iAwTy-0001Ol-3k for gcc-patches@gcc.gnu.org; Thu, 19 Sep 2019 09:28:26 -0400 Received: from localhost (localhost.localdomain [127.0.0.1]) by filtered-rock.gnat.com (Postfix) with ESMTP id 2532B5601D; Thu, 19 Sep 2019 09:28:20 -0400 (EDT) Received: from rock.gnat.com ([127.0.0.1]) by localhost (rock.gnat.com [127.0.0.1]) (amavisd-new, port 10024) with LMTP id 0F0RulREphKw; Thu, 19 Sep 2019 09:28:20 -0400 (EDT) Received: from tron.gnat.com (tron.gnat.com [IPv6:2620:20:4000:0:46a8:42ff:fe0e:e294]) by rock.gnat.com (Postfix) with ESMTP id E5A605602B; Thu, 19 Sep 2019 09:28:19 -0400 (EDT) Received: by tron.gnat.com (Postfix, from userid 4862) id E17C96B4; Thu, 19 Sep 2019 09:28:19 -0400 (EDT) Date: Thu, 19 Sep 2019 09:28:19 -0400 From: Pierre-Marie de Rodat To: gcc-patches@gcc.gnu.org Cc: Eric Botcazou Subject: [Ada] Get rid of useless temporary for slice in overaligned record type Message-ID: <20190919132819.GA41903@adacore.com> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.23 (2014-03-12) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x X-Received-From: 205.232.38.15 X-IsSubscribed: yes This fixes a recent code quality regression for targets that do not require the strict alignment of memory accesses: the compiler would generate a useless temporary for a slice of an array component in an overaligned record type. Running these commands: gcc -c p.adb -gnatws -gnatD grep loop p.adb.dg On the following sources: procedure P (N : Positive) is type Rec1 is record I : Integer; end record; type Arr is array (Positive range <>) of Rec1; type Rec2 is record A : Arr (1 .. 128); end record; for Rec2'Alignment use 8; procedure Proc (A : Arr) is begin null; end; R : Rec2; begin Proc (R.A (1 .. N)); end; Should execute silently. Tested on x86_64-pc-linux-gnu, committed on trunk 2019-09-19 Eric Botcazou gcc/ada/ * exp_util.adb (Is_Possibly_Unaligned_Slice): Do not return true on pure alignment considerations if the target does not require the strict alignment of memory accesses. --- gcc/ada/exp_util.adb +++ gcc/ada/exp_util.adb @@ -8692,9 +8692,11 @@ package body Exp_Util is -- We are definitely in trouble if the record in question -- has an alignment, and either we know this alignment is -- inconsistent with the alignment of the slice, or we don't - -- know what the alignment of the slice should be. + -- know what the alignment of the slice should be. But this + -- really matters only if the target has strict alignment. - if Known_Alignment (Ptyp) + if Target_Strict_Alignment + and then Known_Alignment (Ptyp) and then (Unknown_Alignment (Styp) or else Alignment (Styp) > Alignment (Ptyp)) then