From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.220.29]) by sourceware.org (Postfix) with ESMTPS id 380103858D1E for ; Wed, 29 Mar 2023 12:11:48 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 380103858D1E Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=suse.de Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id 4A2911FDC3; Wed, 29 Mar 2023 12:11:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1680091907; h=from:from:reply-to:date:date:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=/bOk8y8Af0n4kcg71XGBkj7JdtEpqcHsLcnCZqrNXWk=; b=bwxOsKSQCr0Eg3ujJgE0dSP4dkcH1g7TyHJc90nWbtSlPZUgFHiX3E3ikLzt87QoQR57Hf 8gxPOZlzunYBIrL0JtionLwxnq4yjFzfvg0ianqD+Y5wgnsZtxchdWISYlQtd0v1GSBi1V ZtMTJsmwaEj5F8AADnechD8jiZweimQ= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1680091907; h=from:from:reply-to:date:date:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=/bOk8y8Af0n4kcg71XGBkj7JdtEpqcHsLcnCZqrNXWk=; b=QM78uPauHf3E65cw3z7aq8I1PoV7VfCG7afDXynPZ5ZVh/wUMKcvyQI5aVJ1CPT/n8mTH6 +EEvRDoeWuY3nyAw== Received: from wotan.suse.de (wotan.suse.de [10.160.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id 3165D2C141; Wed, 29 Mar 2023 12:11:47 +0000 (UTC) Date: Wed, 29 Mar 2023 12:11:47 +0000 (UTC) From: Richard Biener To: gcc-patches@gcc.gnu.org cc: Jakub Jelinek Subject: [PATCH] tree-optimization/107561 - reduce -Wstringop-overflow false positives User-Agent: Alpine 2.22 (LSU 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-10.6 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,GIT_PATCH_0,MISSING_MID,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Message-ID: <20230329121147.oou8GKTG4cZNWSQvfDj-dTuK-npDnxaLB6Gn7RXZiAk@z> The following tells pointer-query to prefer a zero size when we are querying for the size range for a write into an object we've determined is of zero size. That avoids diagnostics about really varying size arguments that just get a meaningful range for example because they are multiplied by an element size. I've adjusted only one call to get_size_range since that's what I have a testcase for. I think this is the most sensible "workaround" for some of the false positives we see. Bootstrapped on x86_64-unknown-linux-gnu, testing in progress. OK if it succeeds? Thanks, Richard. PR tree-optimization/107561 * gimple-ssa-warn-access.cc (get_size_range): Add flags argument and pass it on. (check_access): When querying for the size range pass SR_ALLOW_ZERO when the known destination size is zero. * g++.dg/pr71488.C: Remove XFAILed bogus diagnostic again. * g++.dg/warn/Warray-bounds-16.C: Likewise. --- gcc/gimple-ssa-warn-access.cc | 19 +++++++++++++------ gcc/testsuite/g++.dg/pr71488.C | 1 - gcc/testsuite/g++.dg/warn/Warray-bounds-16.C | 1 - 3 files changed, 13 insertions(+), 8 deletions(-) diff --git a/gcc/gimple-ssa-warn-access.cc b/gcc/gimple-ssa-warn-access.cc index 88d44690ade..b3de4b77924 100644 --- a/gcc/gimple-ssa-warn-access.cc +++ b/gcc/gimple-ssa-warn-access.cc @@ -1198,10 +1198,10 @@ warn_for_access (location_t loc, tree func, tree expr, int opt, static void get_size_range (range_query *query, tree bound, gimple *stmt, tree range[2], - const offset_int bndrng[2]) + int flags, const offset_int bndrng[2]) { if (bound) - get_size_range (query, bound, stmt, range); + get_size_range (query, bound, stmt, range, flags); if (!bndrng || (bndrng[0] == 0 && bndrng[1] == HOST_WIDE_INT_M1U)) return; @@ -1347,7 +1347,12 @@ check_access (GimpleOrTree exp, tree dstwrite, /* Set RANGE to that of DSTWRITE if non-null, bounded by PAD->DST_BNDRNG if valid. */ gimple *stmt = pad ? pad->stmt : nullptr; - get_size_range (rvals, dstwrite, stmt, range, pad ? pad->dst_bndrng : NULL); + get_size_range (rvals, dstwrite, stmt, range, + /* If the destination has known zero size prefer a zero + size range to avoid false positives if that's a + possibility. */ + integer_zerop (dstsize) ? SR_ALLOW_ZERO : 0, + pad ? pad->dst_bndrng : NULL); tree func = get_callee_fndecl (exp); /* Read vs write access by built-ins can be determined from the const @@ -1442,7 +1447,8 @@ check_access (GimpleOrTree exp, tree dstwrite, { /* Set RANGE to that of MAXREAD, bounded by PAD->SRC_BNDRNG if PAD is nonnull and BNDRNG is valid. */ - get_size_range (rvals, maxread, stmt, range, pad ? pad->src_bndrng : NULL); + get_size_range (rvals, maxread, stmt, range, 0, + pad ? pad->src_bndrng : NULL); location_t loc = get_location (exp); tree size = dstsize; @@ -1489,7 +1495,8 @@ check_access (GimpleOrTree exp, tree dstwrite, { /* Set RANGE to that of MAXREAD, bounded by PAD->SRC_BNDRNG if PAD is nonnull and BNDRNG is valid. */ - get_size_range (rvals, maxread, stmt, range, pad ? pad->src_bndrng : NULL); + get_size_range (rvals, maxread, stmt, range, 0, + pad ? pad->src_bndrng : NULL); /* Set OVERREAD for reads starting just past the end of an object. */ overread = pad->src.sizrng[1] - pad->src.offrng[0] < pad->src_bndrng[0]; range[0] = wide_int_to_tree (sizetype, pad->src_bndrng[0]); @@ -2679,7 +2686,7 @@ pass_waccess::check_strncmp (gcall *stmt) /* Determine the range of the bound first and bail if it fails; it's cheaper than computing the size of the objects. */ tree bndrng[2] = { NULL_TREE, NULL_TREE }; - get_size_range (m_ptr_qry.rvals, bound, stmt, bndrng, adata1.src_bndrng); + get_size_range (m_ptr_qry.rvals, bound, stmt, bndrng, 0, adata1.src_bndrng); if (!bndrng[0] || integer_zerop (bndrng[0])) return; diff --git a/gcc/testsuite/g++.dg/pr71488.C b/gcc/testsuite/g++.dg/pr71488.C index a89e6465a94..ffe30f1afeb 100644 --- a/gcc/testsuite/g++.dg/pr71488.C +++ b/gcc/testsuite/g++.dg/pr71488.C @@ -3,7 +3,6 @@ // { dg-options "-O3 -std=c++11" } // { dg-additional-options "-msse4" { target sse4_runtime } } // { dg-require-effective-target c++11 } -// { dg-bogus "size 0 overflows" "pr107561" { xfail *-*-* } 0 } #include diff --git a/gcc/testsuite/g++.dg/warn/Warray-bounds-16.C b/gcc/testsuite/g++.dg/warn/Warray-bounds-16.C index 49d3437fa1b..89cbadb91c7 100644 --- a/gcc/testsuite/g++.dg/warn/Warray-bounds-16.C +++ b/gcc/testsuite/g++.dg/warn/Warray-bounds-16.C @@ -20,7 +20,6 @@ struct S for (int i = 0; i < m; i++) new (p + i) int (); /* { dg-bogus "bounds" "pr102690" { xfail *-*-* } } */ - // { dg-bogus "size 0 overflows" "pr107561" { xfail ilp32 } .-1 } } }; -- 2.35.3