From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <stable-bounces@dpdk.org>
Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124])
	by inbox.dpdk.org (Postfix) with ESMTP id D1ABBA0548
	for <public@inbox.dpdk.org>; Mon, 26 Apr 2021 15:35:43 +0200 (CEST)
Received: from [217.70.189.124] (localhost [127.0.0.1])
	by mails.dpdk.org (Postfix) with ESMTP id C3F7F411D8;
	Mon, 26 Apr 2021 15:35:43 +0200 (CEST)
Received: from mga05.intel.com (mga05.intel.com [192.55.52.43])
 by mails.dpdk.org (Postfix) with ESMTP id 1487E40140;
 Mon, 26 Apr 2021 15:35:40 +0200 (CEST)
IronPort-SDR: alOjCmpJwx/+bE+zxxFSos+K3xJfuV7nfUMvek1F9YxudW6wc6cQWG/ssD81Zs5vKiehXntWqy
 ITOpHY5lbu1Q==
X-IronPort-AV: E=McAfee;i="6200,9189,9966"; a="281665523"
X-IronPort-AV: E=Sophos;i="5.82,252,1613462400"; d="scan'208";a="281665523"
Received: from fmsmga004.fm.intel.com ([10.253.24.48])
 by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384;
 26 Apr 2021 06:35:39 -0700
IronPort-SDR: 3nd9y/S9V1sRhqY9rT4JhINCAus02FOtJpkMYDNoOMfrGc/VwBQJN2F6t6hM4VAzHVKPQ0/ewi
 zE3Nz6mjJQLg==
X-ExtLoop1: 1
X-IronPort-AV: E=Sophos;i="5.82,252,1613462400"; d="scan'208";a="447277382"
Received: from sivswdev08.ir.intel.com ([10.237.217.47])
 by fmsmga004.fm.intel.com with ESMTP; 26 Apr 2021 06:35:38 -0700
From: Konstantin Ananyev <konstantin.ananyev@intel.com>
To: dev@dpdk.org
Cc: Konstantin Ananyev <konstantin.ananyev@intel.com>,
	stable@dpdk.org
Date: Mon, 26 Apr 2021 14:35:19 +0100
Message-Id: <20210426133519.4777-1-konstantin.ananyev@intel.com>
X-Mailer: git-send-email 2.18.0
In-Reply-To: <20210423135451.11035-1-konstantin.ananyev@intel.com>
References: <20210423135451.11035-1-konstantin.ananyev@intel.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Subject: [dpdk-stable] [PATCH v2] acl: fix build with gcc 11
X-BeenThere: stable@dpdk.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: patches for DPDK stable branches <stable.dpdk.org>
List-Unsubscribe: <https://mails.dpdk.org/options/stable>,
 <mailto:stable-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://mails.dpdk.org/archives/stable/>
List-Post: <mailto:stable@dpdk.org>
List-Help: <mailto:stable-request@dpdk.org?subject=help>
List-Subscribe: <https://mails.dpdk.org/listinfo/stable>,
 <mailto:stable-request@dpdk.org?subject=subscribe>
Errors-To: stable-bounces@dpdk.org
Sender: "stable" <stable-bounces@dpdk.org>

gcc 11 with '-O2' complains about some variables being used without
being initialized:

In file included from ../lib/librte_acl/acl_run_avx512x8.h:201,
                 from ../lib/librte_acl/acl_run_avx512.c:110:
In function ‘start_flow_avx512x8’,
    inlined from ‘search_trie_avx512x8.constprop’ at ../lib/librte_acl/acl_run_avx512_common.h:317:2:
../lib/librte_acl/acl_run_avx512_common.h:210:13: warning: ‘pdata’ is used uninitialized [-Wuninitialized]
In file included from ../lib/librte_acl/acl_run_avx512x8.h:201,
                 from ../lib/librte_acl/acl_run_avx512.c:110:
../lib/librte_acl/acl_run_avx512_common.h: In function ‘search_trie_avx512x8.constprop’:
../lib/librte_acl/acl_run_avx512_common.h:314:32: note: ‘pdata’ declared here
In file included from ../lib/librte_acl/acl_run_avx512x8.h:201,
                 from ../lib/librte_acl/acl_run_avx512.c:110:
....

Indeed, these variables are not explicitly initialized,
but this is done intentionally.
We rely on constant mask value that we pass to start_flow*() functions
as a parameter to mask out uninitialized values.
Note that '-O3' doesn't produce this warning.
Anyway, to support clean build with gcc-11 this patch adds
explicit initialization for these variables.
I checked the output binary: with '-O3' both clang and gcc 10/11
generate no extra code for it.
Also performance test didn't reveal any regressions.

Bugzilla ID: 673
Fixes: b64c2295f7fc ("acl: add 256-bit AVX512 classify method")
Fixes: 45da22e42ec3 ("acl: add 512-bit AVX512 classify method")
Cc: stable@dpdk.org

Reported-by: Ali Alnubani <alialnu@nvidia.com>
Signed-off-by: Konstantin Ananyev <konstantin.ananyev@intel.com>
---
v2: update commit log
---
 lib/acl/acl_run_avx512_common.h | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/lib/acl/acl_run_avx512_common.h b/lib/acl/acl_run_avx512_common.h
index fafaf591e..fbad74d45 100644
--- a/lib/acl/acl_run_avx512_common.h
+++ b/lib/acl/acl_run_avx512_common.h
@@ -303,6 +303,28 @@ _F_(match_check_process)(struct acl_flow_avx512 *flow, uint32_t fm[2],
 	}
 }
 
+static inline void
+_F_(reset_flow_vars)(_T_simd di[2], _T_simd idx[2], _T_simd pdata[4],
+	_T_simd tr_lo[2], _T_simd tr_hi[2])
+{
+	di[0] = _M_SI_(setzero)();
+	di[1] = _M_SI_(setzero)();
+
+	idx[0] = _M_SI_(setzero)();
+	idx[1] = _M_SI_(setzero)();
+
+	pdata[0] = _M_SI_(setzero)();
+	pdata[1] = _M_SI_(setzero)();
+	pdata[2] = _M_SI_(setzero)();
+	pdata[3] = _M_SI_(setzero)();
+
+	tr_lo[0] = _M_SI_(setzero)();
+	tr_lo[1] = _M_SI_(setzero)();
+
+	tr_hi[0] = _M_SI_(setzero)();
+	tr_hi[1] = _M_SI_(setzero)();
+}
+
 /*
  * Perform search for up to (2 * _N_) flows in parallel.
  * Use two sets of metadata, each serves _N_ flows max.
@@ -313,6 +335,8 @@ _F_(search_trie)(struct acl_flow_avx512 *flow)
 	uint32_t fm[2];
 	_T_simd di[2], idx[2], in[2], pdata[4], tr_lo[2], tr_hi[2];
 
+	_F_(reset_flow_vars)(di, idx, pdata, tr_lo, tr_hi);
+
 	/* first 1B load */
 	_F_(start_flow)(flow, _SIMD_MASK_BIT_, _SIMD_MASK_MAX_,
 			&pdata[0], &idx[0], &di[0]);
-- 
2.26.3