From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out1.suse.de (smtp-out1.suse.de [IPv6:2001:67c:2178:6::1c]) by sourceware.org (Postfix) with ESMTPS id C856938582BF for ; Fri, 9 Sep 2022 12:31:27 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org C856938582BF 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-out1.suse.de (Postfix) with ESMTP id A18DB22DB5 for ; Fri, 9 Sep 2022 12:31:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1662726686; h=from:from:reply-to:date:date:to:to:cc:mime-version:mime-version: content-type:content-type; bh=U+6qrLuHKoFkyQlKyI6kXJXzCDdsEEPsVggblGXWlnA=; b=VwZPc0eqcKusKdfJ9Equki1HahdVEqrTswcD23IAg2s/79bTK3oxAQRnYBMu2pnhsMRC8g pACp9W2GFEc7Ev8TAkvqcmK/JVAmQeWzkbvA0CmdnJfgo/m5P9R/xOayYOZQjljdnboeX4 DEmhaRNQwnpcCy62Iv6nH5BrsWRdVJs= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1662726686; h=from:from:reply-to:date:date:to:to:cc:mime-version:mime-version: content-type:content-type; bh=U+6qrLuHKoFkyQlKyI6kXJXzCDdsEEPsVggblGXWlnA=; b=wNK0XC2Jyxk+n6bW7rFmY2xzf3nrPv0onkNhspnuuNCp3YCWlyymdxaMryzgvLqgkE+udN iAQ+LnqNSYSpPDBA== 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 998222C141 for ; Fri, 9 Sep 2022 12:31:26 +0000 (UTC) Date: Fri, 9 Sep 2022 12:31:26 +0000 (UTC) From: Richard Biener To: gcc-patches@gcc.gnu.org Subject: [PATCH] tree-optimization/106722 - avoid invalid pointer association in predcom 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=-10.7 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,T_SCC_BODY_TEXT_LINE 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: <20220909123126.P24RpRh5j2iWda41fZBGD7FhoeW5UpbNUSnPpwEWmuY@z> When predictive commoning builds a reference for iteration N it prematurely associates a constant offset into the MEM_REF offset operand which can be invalid if the base pointer then points outside of an object which alias-analysis does not consider valid. Bootstrapped and tested on x86_64-unknown-linux-gnu, pushed to trunk sofar. PR tree-optimization/106722 * tree-predcom.cc (ref_at_iteration): Do not associate the constant part of the offset into the MEM_REF offset operand, across a non-zero offset. * gcc.dg/torture/pr106892.c: New testcase. --- gcc/testsuite/gcc.dg/torture/pr106892.c | 30 +++++++++++++++++++++++++ gcc/tree-predcom.cc | 18 +++++++++++++-- 2 files changed, 46 insertions(+), 2 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr106892.c diff --git a/gcc/testsuite/gcc.dg/torture/pr106892.c b/gcc/testsuite/gcc.dg/torture/pr106892.c new file mode 100644 index 00000000000..73a66a037b7 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr106892.c @@ -0,0 +1,30 @@ +/* { dg-do run } */ + +int a, b, c, d, e; +int f[8]; +static int g() { + while (a) + a >>= 4; + return 0; +} +static int h(int i) { + if (i >= '0') + return i - '0'; + //__builtin_unreachable (); +} +void __attribute__((noipa)) j(int i) { + for (b = 2; g() <= 7; b++) + if (i) { + for (; e <= 7; e++) + for (c = 1; c <= 7; c++) { + d = h(b + '0'); + f[-d + 4] ^= 3; + } + return; + } +} +int main() { + j(1); + if (f[2] != 0) + __builtin_abort (); +} diff --git a/gcc/tree-predcom.cc b/gcc/tree-predcom.cc index 5d923fba170..a6e45e36ffd 100644 --- a/gcc/tree-predcom.cc +++ b/gcc/tree-predcom.cc @@ -1771,10 +1771,24 @@ ref_at_iteration (data_reference_p dr, int iter, ref = TREE_OPERAND (ref, 0); } } - tree addr = fold_build_pointer_plus (DR_BASE_ADDRESS (dr), off); + /* We may not associate the constant offset across the pointer plus + expression because that might form a pointer to before the object + then. But for some cases we can retain that to allow tree_could_trap_p + to return false - see gcc.dg/tree-ssa/predcom-1.c */ + tree addr, alias_ptr; + if (integer_zerop (off)) + { + alias_ptr = fold_convert (reference_alias_ptr_type (ref), coff); + addr = DR_BASE_ADDRESS (dr); + } + else + { + alias_ptr = build_zero_cst (reference_alias_ptr_type (ref)); + off = size_binop (PLUS_EXPR, off, coff); + addr = fold_build_pointer_plus (DR_BASE_ADDRESS (dr), off); + } addr = force_gimple_operand_1 (unshare_expr (addr), stmts, is_gimple_mem_ref_addr, NULL_TREE); - tree alias_ptr = fold_convert (reference_alias_ptr_type (ref), coff); tree type = build_aligned_type (TREE_TYPE (ref), get_object_alignment (ref)); ref = build2 (MEM_REF, type, addr, alias_ptr); -- 2.35.3