From patchwork Sat Nov 16 13:55:14 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Richard Sandiford X-Patchwork-Id: 1196122 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=209.132.180.131; helo=sourceware.org; envelope-from=gcc-patches-return-513790-incoming=patchwork.ozlabs.org@gcc.gnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=gcc.gnu.org header.i=@gcc.gnu.org header.b="f0Kegncx"; 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 47FcDc4ynzz9s4Y for ; Sun, 17 Nov 2019 00:55:26 +1100 (AEDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender:from :to:subject:date:message-id:mime-version:content-type; q=dns; s= default; b=Fct2u1mAKuCnY/n7uKGDy7GJKJC+9zyd6Umty5Y+pBH7SwtXhL7nY CnA5F4db8HYuVHExreVfQzjNSbXo15hqBNpq1SAE+BdtTWxcv9mYULYhxknTfOnW T5gWxvFbtN2/SPPdaw4CKo4hmlZ9GYHR1igNjE63RpWajRHCvu0DTA= 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:from :to:subject:date:message-id:mime-version:content-type; s= default; bh=HebYNg262jifa3NSIHpIttyJ3Qk=; b=f0Kegncxks9KSDmWK+N5 I27BF6LivnMuaM1IiiW1aC0yriRqWnW5HJfuWHh0oSO8y8GeqWsgZmmNTpsOmLlM 0wpNmt9oaz343UPqqHH/wfvAsUV2dltH9pLFP93m09x1cMiW651jRDm2WaEs2qn2 VULYosw8rEJucAmKpLEgRmQ= Received: (qmail 1524 invoked by alias); 16 Nov 2019 13:55:19 -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 1516 invoked by uid 89); 16 Nov 2019 13:55:19 -0000 Authentication-Results: sourceware.org; auth=none X-Spam-SWARE-Status: No, score=-9.7 required=5.0 tests=AWL, BAYES_00, GIT_PATCH_2, GIT_PATCH_3, SPF_PASS autolearn=ham version=3.3.1 spammy=HX-Languages-Length:971 X-HELO: foss.arm.com Received: from foss.arm.com (HELO foss.arm.com) (217.140.110.172) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Sat, 16 Nov 2019 13:55:18 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3D7F730E for ; Sat, 16 Nov 2019 05:55:16 -0800 (PST) Received: from localhost (e121540-lin.manchester.arm.com [10.32.98.126]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D81EC3F6C4 for ; Sat, 16 Nov 2019 05:55:15 -0800 (PST) From: Richard Sandiford To: gcc-patches@gcc.gnu.org Mail-Followup-To: gcc-patches@gcc.gnu.org, richard.sandiford@arm.com Subject: Add an empty constructor shortcut to build_vector_from_ctor Date: Sat, 16 Nov 2019 13:55:14 +0000 Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 X-IsSubscribed: yes Empty vector constructors are equivalent to zero vectors. If we handle that case directly, we can support it for variable-length vectors and can hopefully make things more efficient for fixed-length vectors. This is needed by a later C++ patch. Tested on aarch64-linux-gnu and x86_64-linux-gnu. OK to install? Richard 2019-11-16 Richard Sandiford gcc/ * tree.c (build_vector_from_ctor): Directly return a zero vector for empty constructors. Index: gcc/tree.c =================================================================== --- gcc/tree.c 2019-11-14 14:55:04.415447600 +0000 +++ gcc/tree.c 2019-11-16 13:53:28.609006588 +0000 @@ -1858,6 +1858,9 @@ make_vector (unsigned log2_npatterns, tree build_vector_from_ctor (tree type, vec *v) { + if (vec_safe_length (v) == 0) + return build_zero_cst (type); + unsigned HOST_WIDE_INT idx, nelts; tree value;