From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by sourceware.org (Postfix) with ESMTPS id 10FD3385841C for ; Tue, 9 Jan 2024 21:59:38 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 10FD3385841C Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=redhat.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 10FD3385841C Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=170.10.133.124 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1704837579; cv=none; b=NBTu/C5XiGOBMj25vWb2YVc7hl1VgKzTYpeDngTp7A+wHZbChP5blTzYWkBByAxgV+8UlGs6pdgIgd56QRBgeYccExDxL27RKlE/a32BCxs5yi9Xz8NOJkyTewb/wtmWYm+WE6dXdiQwq+m7b++L35lgHHUAFnBMD3VHF3EMjA0= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1704837579; c=relaxed/simple; bh=7HBjqHtEVKRkPNiI29P9EnA9ni5yco6aZrSBT7sFDgY=; h=DKIM-Signature:From:To:Subject:Date:Message-ID:MIME-Version; b=Ixv0yNlIdv0nPK4Rsi0yEOiMJBclThOMmYVIcmQ0x6PyLWmPzribBZvts69c1nX2qyMIJj7Nuws3K8suYPYQlTdTXNAYflSrBlJ5JroeCJ9Wm2dqgFEsIJwfKT6HOnPgJt70Sf2Kvyew2MFefOvzV251Z6xQk5X4haH5jqlYs1c= ARC-Authentication-Results: i=1; server2.sourceware.org DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1704837577; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=J+tJ6aVColgudDOVP2HM1WCEzb19E7hU7G1cO5cEric=; b=OVwE1Ovkng/cUAjZCMSyQnI9HMyRl4XOYHaOY/dw6fQIBW49+xb54Qz5si2e9vNOXOvjfv QG6cF8E3EusrOJAplMse3W1Q6zVackqJei3KhJTjMrOG+KDE0yt88KoTx2MYOTlBMvS7DK RDhWzCUHBzSqRb0YzrUUNsQJ51mOnho= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-372-IhyS6HkvNAaO52pelBGaYQ-1; Tue, 09 Jan 2024 16:59:34 -0500 X-MC-Unique: IhyS6HkvNAaO52pelBGaYQ-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 30181833AE2; Tue, 9 Jan 2024 21:59:34 +0000 (UTC) Received: from localhost (unknown [10.42.28.185]) by smtp.corp.redhat.com (Postfix) with ESMTP id ECDE01C060AF; Tue, 9 Jan 2024 21:59:33 +0000 (UTC) From: Jonathan Wakely To: libstdc++@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: [PATCH] libstdc++: Prefer posix_memalign for aligned-new [PR113258] Date: Tue, 9 Jan 2024 21:57:25 +0000 Message-ID: <20240109215933.4054953-1-jwakely@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.7 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-13.1 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,RCVD_IN_DNSWL_NONE,RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE,TXREP,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Does anybody see any problem with making this change, so that we avoid the problem described in the PR? -- >8 -- As described in PR libstdc++/113258 there are old versions of tcmalloc which replace malloc and related APIs, but do not repalce aligned_alloc because it didn't exist at the time they were released. This means that when operator new(size_t, align_val_t) uses aligned_alloc to obtain memory, it comes from libc's aligned_alloc not from tcmalloc. But when operator delete(void*, size_t, align_val_t) uses free to deallocate the memory, that goes to tcmalloc's replacement version of free, which doesn't know how to free it. If we give preference to the older posix_memalign instead of aligned_alloc then we're more likely to use a function that will be compatible with the replacement version of free. Because posix_memalign has been around for longer, it's more likely that old third-party malloc replacements will also replace posix_memalign alongside malloc and free. libstdc++-v3/ChangeLog: PR libstdc++/113258 * libsupc++/new_opa.cc: Prefer to use posix_memalign if available. --- libstdc++-v3/libsupc++/new_opa.cc | 26 +++++++++++++++----------- 1 file changed, 15 insertions(+), 11 deletions(-) diff --git a/libstdc++-v3/libsupc++/new_opa.cc b/libstdc++-v3/libsupc++/new_opa.cc index 8326b7497fe..35606e1c1b3 100644 --- a/libstdc++-v3/libsupc++/new_opa.cc +++ b/libstdc++-v3/libsupc++/new_opa.cc @@ -46,12 +46,12 @@ using std::bad_alloc; using std::size_t; extern "C" { -# if _GLIBCXX_HAVE_ALIGNED_ALLOC +# if _GLIBCXX_HAVE_POSIX_MEMALIGN + void *posix_memalign(void **, size_t alignment, size_t size); +# elif _GLIBCXX_HAVE_ALIGNED_ALLOC void *aligned_alloc(size_t alignment, size_t size); # elif _GLIBCXX_HAVE__ALIGNED_MALLOC void *_aligned_malloc(size_t size, size_t alignment); -# elif _GLIBCXX_HAVE_POSIX_MEMALIGN - void *posix_memalign(void **, size_t alignment, size_t size); # elif _GLIBCXX_HAVE_MEMALIGN void *memalign(size_t alignment, size_t size); # else @@ -63,13 +63,10 @@ extern "C" #endif namespace __gnu_cxx { -#if _GLIBCXX_HAVE_ALIGNED_ALLOC -using ::aligned_alloc; -#elif _GLIBCXX_HAVE__ALIGNED_MALLOC -static inline void* -aligned_alloc (std::size_t al, std::size_t sz) -{ return _aligned_malloc(sz, al); } -#elif _GLIBCXX_HAVE_POSIX_MEMALIGN +// Prefer posix_memalign if available, because it's older than aligned_alloc +// and so more likely to be provided by replacement malloc libraries that +// predate the addition of aligned_alloc. See PR libstdc++/113258. +#if _GLIBCXX_HAVE_POSIX_MEMALIGN static inline void* aligned_alloc (std::size_t al, std::size_t sz) { @@ -83,6 +80,12 @@ aligned_alloc (std::size_t al, std::size_t sz) return ptr; return nullptr; } +#elif _GLIBCXX_HAVE_ALIGNED_ALLOC +using ::aligned_alloc; +#elif _GLIBCXX_HAVE__ALIGNED_MALLOC +static inline void* +aligned_alloc (std::size_t al, std::size_t sz) +{ return _aligned_malloc(sz, al); } #elif _GLIBCXX_HAVE_MEMALIGN static inline void* aligned_alloc (std::size_t al, std::size_t sz) @@ -128,7 +131,8 @@ operator new (std::size_t sz, std::align_val_t al) if (__builtin_expect (sz == 0, false)) sz = 1; -#if _GLIBCXX_HAVE_ALIGNED_ALLOC +#if _GLIBCXX_HAVE_POSIX_MEMALIGN +#elif _GLIBCXX_HAVE_ALIGNED_ALLOC # if defined _AIX || defined __APPLE__ /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement * that alignment is a multiple of sizeof(void*). -- 2.43.0