From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2a07:de40:b251:101:10:150:64:2]) by sourceware.org (Postfix) with ESMTPS id 2DE673858D28 for ; Mon, 26 Feb 2024 14:15:04 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 2DE673858D28 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=suse.de Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=suse.de ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 2DE673858D28 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=2a07:de40:b251:101:10:150:64:2 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1708956906; cv=none; b=q5skD2d8SCWDEC0iWVKqBphtgrEl2cbYNU7XcUrwelNK6WWXuQwzl9PymI74eHGa9Ryz5IxWHimnYkctzlTF8gdA/+wpEw15ODoJagiXqdGLbXY81aKbtOkGwQbmcMrnmcvFMcEtsrH4aUWdLwn2f39yUoE0OehNj/w4rIBkz2g= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1708956906; c=relaxed/simple; bh=s1G9mZs2kt6aL3E45l7fZFmoUVx4VEsTR/nUTjTQSlA=; h=DKIM-Signature:DKIM-Signature:DKIM-Signature:DKIM-Signature:Date: From:To:Subject:MIME-Version; b=fZT4oFe6y4BWg2/MNiEhSNn0BWI3IHjjc6SavA0uusPPDbRuzBm+V6PHXiePPXz8UuZFhlFiP6+iB0HYgoQJBlWiWSMZP2CMCpiVD/V/HEJ0ChYCMjm6mNeX+/b6rflCVjyjvG66OfR/1HM/Ytxlu9osWG4cC9VE0JaeKybIDVw= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from [10.168.4.150] (unknown [10.168.4.150]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id 1C4CF1FB51; Mon, 26 Feb 2024 14:15:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1708956903; h=from:from:reply-to:date:date:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=Camneuf59VHFmyD7WnWpc5jHD9n4xOMKDG4OnIh8j1w=; b=Oz78ZKWxJw+GiU20MZOxxOz/a2bs5zu/b3cfSxrQtNmdTVWOZ82mHprN1f/clNlCS4zDD8 35bVEcQNL2kHBHDGibgDesC7Z1C364upt8qUHDh6XNCFebyxnS6bzoEsrtxRIAeYyxlzB0 LvJM5O/THli7axATIFLz5Tw/V8G8lIk= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1708956903; h=from:from:reply-to:date:date:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=Camneuf59VHFmyD7WnWpc5jHD9n4xOMKDG4OnIh8j1w=; b=r8yIzxspQkj736wXJJYL81RzIfeZqb5jToHdClaUa1WNv4P+01LXTfIxXOt/YcoxrS00+E j89XypZDBJuwYEAQ== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1708956903; h=from:from:reply-to:date:date:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=Camneuf59VHFmyD7WnWpc5jHD9n4xOMKDG4OnIh8j1w=; b=Oz78ZKWxJw+GiU20MZOxxOz/a2bs5zu/b3cfSxrQtNmdTVWOZ82mHprN1f/clNlCS4zDD8 35bVEcQNL2kHBHDGibgDesC7Z1C364upt8qUHDh6XNCFebyxnS6bzoEsrtxRIAeYyxlzB0 LvJM5O/THli7axATIFLz5Tw/V8G8lIk= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1708956903; h=from:from:reply-to:date:date:to:to:cc:cc:mime-version:mime-version: content-type:content-type; bh=Camneuf59VHFmyD7WnWpc5jHD9n4xOMKDG4OnIh8j1w=; b=r8yIzxspQkj736wXJJYL81RzIfeZqb5jToHdClaUa1WNv4P+01LXTfIxXOt/YcoxrS00+E j89XypZDBJuwYEAQ== Date: Mon, 26 Feb 2024 15:15:02 +0100 (CET) From: Richard Biener To: gcc-patches@gcc.gnu.org cc: Jakub Jelinek Subject: [PATCH] tree-optimization/114074 - CHREC multiplication and undefined overflow MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Authentication-Results: smtp-out2.suse.de; none X-Spam-Level: X-Spam-Score: -1.67 X-Spamd-Result: default: False [-1.67 / 50.00]; ARC_NA(0.00)[]; FROM_HAS_DN(0.00)[]; TO_DN_SOME(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MISSING_MID(2.50)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.07)[-0.368]; RCPT_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; RCVD_COUNT_ZERO(0.00)[0]; FROM_EQ_ENVFROM(0.00)[]; MIME_TRACE(0.00)[0:+]; BAYES_HAM(-3.00)[100.00%] 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,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: <20240226141502.uZqa5qjXxe5HFn9UwP5DpJXWNaqxVALgR4ZDbyhe-qg@z> When folding a multiply CHRECs are handled like {a, +, b} * c is {a*c, +, b*c} but that isn't generally correct when overflow invokes undefined behavior. The following uses unsigned arithmetic unless either a is zero or a and b have the same sign. I've used simple early outs for INTEGER_CSTs and otherwise use a range-query since we lack a tree_expr_nonpositive_p. Bootstrapped and tested on x86_64-unknown-linux-gnu. I'm not sure it's worth using ranger, there might be also more cases where the integer multiply is OK, say when abs (A) > abs (B). But also {-2, +, 2}, but not for {1, +, -1} for example. OK? Thanks, Richard. PR tree-optimization/114074 * tree-chrec.h (chrec_convert_rhs): Default at_stmt arg to NULL. * tree-chrec.cc (chrec_fold_multiply): Canonicalize inputs. Handle poly vs. non-poly multiplication correctly with respect to undefined behavior on overflow. * gcc.dg/torture/pr114074.c: New testcase. * gcc.dg/pr68317.c: Adjust expected location of diagnostic. --- gcc/testsuite/gcc.dg/pr68317.c | 4 +- gcc/testsuite/gcc.dg/torture/pr114074.c | 27 +++++++++++++ gcc/tree-chrec.cc | 53 ++++++++++++++++++++----- gcc/tree-chrec.h | 2 +- 4 files changed, 72 insertions(+), 14 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/torture/pr114074.c diff --git a/gcc/testsuite/gcc.dg/pr68317.c b/gcc/testsuite/gcc.dg/pr68317.c index bd053a7522b..06cd2e1da9c 100644 --- a/gcc/testsuite/gcc.dg/pr68317.c +++ b/gcc/testsuite/gcc.dg/pr68317.c @@ -12,8 +12,8 @@ foo () { int32_t index = 0; - for (index; index <= 10; index--) // expected warning here + for (index; index <= 10; index--) /* { dg-warning "iteration \[0-9\]+ invokes undefined behavior" } */ /* Result of the following multiply will overflow when converted to signed int32_t. */ - bar ((0xcafe + index) * 0xdead); /* { dg-warning "iteration \[0-9\]+ invokes undefined behavior" } */ + bar ((0xcafe + index) * 0xdead); } diff --git a/gcc/testsuite/gcc.dg/torture/pr114074.c b/gcc/testsuite/gcc.dg/torture/pr114074.c new file mode 100644 index 00000000000..336e97673c3 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr114074.c @@ -0,0 +1,27 @@ +/* { dg-do run } */ + +int a, b, d; + +__attribute__((noipa)) void +foo (void) +{ + ++d; +} + +int +main () +{ + for (a = 0; a > -3; a -= 2) + { + int c = a; + b = __INT_MAX__ - 3000; + a = ~c * b; + foo (); + if (!a) + break; + a = c; + } + if (d != 2) + __builtin_abort (); + return 0; +} diff --git a/gcc/tree-chrec.cc b/gcc/tree-chrec.cc index 61456fe1141..1b1023f68af 100644 --- a/gcc/tree-chrec.cc +++ b/gcc/tree-chrec.cc @@ -38,6 +38,8 @@ along with GCC; see the file COPYING3. If not see #include "gimple.h" #include "tree-ssa-loop.h" #include "dumpfile.h" +#include "value-range.h" +#include "value-query.h" #include "tree-scalar-evolution.h" /* Extended folder for chrecs. */ @@ -404,6 +406,10 @@ chrec_fold_multiply (tree type, || automatically_generated_chrec_p (op1)) return chrec_fold_automatically_generated_operands (op0, op1); + if (TREE_CODE (op0) != POLYNOMIAL_CHREC + && TREE_CODE (op1) == POLYNOMIAL_CHREC) + std::swap (op0, op1); + switch (TREE_CODE (op0)) { case POLYNOMIAL_CHREC: @@ -428,10 +434,41 @@ chrec_fold_multiply (tree type, if (integer_zerop (op1)) return build_int_cst (type, 0); - return build_polynomial_chrec - (CHREC_VARIABLE (op0), - chrec_fold_multiply (type, CHREC_LEFT (op0), op1), - chrec_fold_multiply (type, CHREC_RIGHT (op0), op1)); + /* When overflow is undefined and CHREC_LEFT/RIGHT do not have the + same sign or CHREC_LEFT is zero then folding the multiply into + the addition does not have the same behavior on overflow. Use + unsigned arithmetic in that case. */ + value_range rl, rr; + if (!ANY_INTEGRAL_TYPE_P (type) + || TYPE_OVERFLOW_WRAPS (type) + || integer_zerop (CHREC_LEFT (op0)) + || (TREE_CODE (CHREC_LEFT (op0)) == INTEGER_CST + && TREE_CODE (CHREC_RIGHT (op0)) == INTEGER_CST + && (tree_int_cst_sgn (CHREC_LEFT (op0)) + == tree_int_cst_sgn (CHREC_RIGHT (op0)))) + || (get_range_query (cfun)->range_of_expr (rl, CHREC_LEFT (op0)) + && !rl.undefined_p () + && (rl.nonpositive_p () || rl.nonnegative_p ()) + && get_range_query (cfun)->range_of_expr (rr, CHREC_RIGHT (op0)) + && !rr.undefined_p () + && ((rl.nonpositive_p () && rr.nonpositive_p ()) + || (rl.nonnegative_p () && rr.nonnegative_p ())))) + return build_polynomial_chrec + (CHREC_VARIABLE (op0), + chrec_fold_multiply (type, CHREC_LEFT (op0), op1), + chrec_fold_multiply (type, CHREC_RIGHT (op0), op1)); + else + { + tree utype = unsigned_type_for (type); + op1 = chrec_convert_rhs (utype, op1); + tree tem = build_polynomial_chrec + (CHREC_VARIABLE (op0), + chrec_fold_multiply + (utype, chrec_convert_rhs (utype, CHREC_LEFT (op0)), op1), + chrec_fold_multiply + (utype, chrec_convert_rhs (utype, CHREC_RIGHT (op0)), op1)); + return chrec_convert_rhs (type, tem); + } } CASE_CONVERT: @@ -449,13 +486,7 @@ chrec_fold_multiply (tree type, switch (TREE_CODE (op1)) { case POLYNOMIAL_CHREC: - gcc_checking_assert - (!chrec_contains_symbols_defined_in_loop (op1, - CHREC_VARIABLE (op1))); - return build_polynomial_chrec - (CHREC_VARIABLE (op1), - chrec_fold_multiply (type, CHREC_LEFT (op1), op0), - chrec_fold_multiply (type, CHREC_RIGHT (op1), op0)); + gcc_unreachable (); CASE_CONVERT: if (tree_contains_chrecs (op1, NULL)) diff --git a/gcc/tree-chrec.h b/gcc/tree-chrec.h index e3a5ba55885..8003eb53a39 100644 --- a/gcc/tree-chrec.h +++ b/gcc/tree-chrec.h @@ -63,7 +63,7 @@ extern tree chrec_fold_plus (tree, tree, tree); extern tree chrec_fold_minus (tree, tree, tree); extern tree chrec_fold_multiply (tree, tree, tree); extern tree chrec_convert (tree, tree, gimple *, bool = true, tree = NULL); -extern tree chrec_convert_rhs (tree, tree, gimple *); +extern tree chrec_convert_rhs (tree, tree, gimple * = NULL); extern tree chrec_convert_aggressive (tree, tree, bool *); /* Operations. */ -- 2.35.3