From patchwork Thu Nov 11 19:41:14 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddhesh Poyarekar X-Patchwork-Id: 1554075 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=gotplt.org header.i=@gotplt.org header.a=rsa-sha1 header.s=gotplt.org header.b=VaEzlemd; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=8.43.85.97; helo=sourceware.org; envelope-from=gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org; receiver=) Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (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 bilbo.ozlabs.org (Postfix) with ESMTPS id 4HqsYt687Yz9s1l for ; Fri, 12 Nov 2021 06:42:26 +1100 (AEDT) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 47E823857829 for ; Thu, 11 Nov 2021 19:42:23 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from bee.birch.relay.mailchannels.net (bee.birch.relay.mailchannels.net [23.83.209.14]) by sourceware.org (Postfix) with ESMTPS id AC92A3857C5D for ; Thu, 11 Nov 2021 19:41:31 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org AC92A3857C5D Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=gotplt.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gotplt.org X-Sender-Id: dreamhost|x-authsender|siddhesh@gotplt.org Received: from relay.mailchannels.net (localhost [127.0.0.1]) by relay.mailchannels.net (Postfix) with ESMTP id 34F96781494; Thu, 11 Nov 2021 19:41:30 +0000 (UTC) Received: from pdx1-sub0-mail-a304.dreamhost.com (100-96-39-10.trex.outbound.svc.cluster.local [100.96.39.10]) (Authenticated sender: dreamhost) by relay.mailchannels.net (Postfix) with ESMTPA id A92E4780787; Thu, 11 Nov 2021 19:41:29 +0000 (UTC) X-Sender-Id: dreamhost|x-authsender|siddhesh@gotplt.org Received: from pdx1-sub0-mail-a304.dreamhost.com (pop.dreamhost.com [64.90.62.162]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384) by 100.96.39.10 (trex/6.4.3); Thu, 11 Nov 2021 19:41:30 +0000 X-MC-Relay: Neutral X-MailChannels-SenderId: dreamhost|x-authsender|siddhesh@gotplt.org X-MailChannels-Auth-Id: dreamhost X-Decisive-Whimsical: 506afaab35a2714a_1636659689936_178636315 X-MC-Loop-Signature: 1636659689936:1357271222 X-MC-Ingress-Time: 1636659689936 Received: from rhbox.redhat.com (unknown [1.186.121.107]) (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) (Authenticated sender: siddhesh@gotplt.org) by pdx1-sub0-mail-a304.dreamhost.com (Postfix) with ESMTPSA id 4HqsXl6tNMz2Y; Thu, 11 Nov 2021 11:41:27 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=gotplt.org; s=gotplt.org; t=1636659689; bh=mWrnqL8m1bNFt4a0Gx6O9R/ZgWY=; h=From:To:Cc:Subject:Date:Content-Transfer-Encoding; b=VaEzlemd5imWRJ7PdA5h52AyU3sgyelnv668Cs3XI3hs82v+Xt+Rue7ogYfdVuEvI 5BqRgtInWaiDrgxqk8QYXjHm5xpgkocCKTCCXuSnqpb+2tQ1gVUgImnTJwzh8NjkeW vw6TzaR4ipUIYVXOoZK2sCScbeDDWKyYseD5kvrM= From: Siddhesh Poyarekar To: gcc-patches@gcc.gnu.org Subject: [PATCH 1/3] gimple-fold: Transform stp*cpy_chk to str*cpy directly Date: Fri, 12 Nov 2021 01:11:14 +0530 Message-Id: <20211111194116.1626980-2-siddhesh@gotplt.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211111194116.1626980-1-siddhesh@gotplt.org> References: <20211111194116.1626980-1-siddhesh@gotplt.org> MIME-Version: 1.0 X-Spam-Status: No, score=-3038.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, RCVD_IN_SBL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Sender: "Gcc-patches" Avoid going through another folding cycle and use the ignore flag to directly transform BUILT_IN_STPCPY_CHK to BUILT_IN_STRCPY when set, likewise for BUILT_IN_STPNCPY_CHK to BUILT_IN_STPNCPY. Dump the transformation in dump_file so that we can verify in tests that the direct transformation actually happened. gcc/ChangeLog: * gimple-fold.c (gimple_fold_builtin_stxcpy_chk, gimple_fold_builtin_stxncpy_chk): Use BUILT_IN_STRNCPY if return value is not used. gcc/testsuite/ChangeLog: * gcc.dg/fold-stringops.c: New test. Signed-off-by: Siddhesh Poyarekar --- gcc/gimple-fold.c | 50 +++++++++++++++++-------- gcc/testsuite/gcc.dg/fold-stringops-1.c | 23 ++++++++++++ 2 files changed, 57 insertions(+), 16 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/fold-stringops-1.c diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index 6e25a7c05db..92e15784803 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -3088,6 +3088,19 @@ gimple_fold_builtin_memory_chk (gimple_stmt_iterator *gsi, return true; } +static void +dump_transformation (gimple *from, gimple *to) +{ + if (dump_file && (dump_flags & TDF_DETAILS)) + { + fprintf (dump_file, "transformed "); + print_generic_expr (dump_file, gimple_call_fn (from), dump_flags); + fprintf (dump_file, " to "); + print_generic_expr (dump_file, gimple_call_fn (to), dump_flags); + fprintf (dump_file, "\n"); + } +} + /* Fold a call to the __st[rp]cpy_chk builtin. DEST, SRC, and SIZE are the arguments to the call. IGNORE is true if return value can be ignored. FCODE is the BUILT_IN_* @@ -3184,12 +3197,13 @@ gimple_fold_builtin_stxcpy_chk (gimple_stmt_iterator *gsi, } /* If __builtin_st{r,p}cpy_chk is used, assume st{r,p}cpy is available. */ - fn = builtin_decl_explicit (fcode == BUILT_IN_STPCPY_CHK + fn = builtin_decl_explicit (fcode == BUILT_IN_STPCPY_CHK && !ignore ? BUILT_IN_STPCPY : BUILT_IN_STRCPY); if (!fn) return false; gimple *repl = gimple_build_call (fn, 2, dest, src); + dump_transformation (stmt, repl); replace_call_with_call_and_fold (gsi, repl); return true; } @@ -3209,19 +3223,6 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, bool ignore = gimple_call_lhs (stmt) == NULL_TREE; tree fn; - if (fcode == BUILT_IN_STPNCPY_CHK && ignore) - { - /* If return value of __stpncpy_chk is ignored, - optimize into __strncpy_chk. */ - fn = builtin_decl_explicit (BUILT_IN_STRNCPY_CHK); - if (fn) - { - gimple *repl = gimple_build_call (fn, 4, dest, src, len, size); - replace_call_with_call_and_fold (gsi, repl); - return true; - } - } - if (! tree_fits_uhwi_p (size)) return false; @@ -3234,7 +3235,23 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, For MAXLEN only allow optimizing into non-_ocs function if SIZE is >= MAXLEN, never convert to __ocs_fail (). */ if (maxlen == NULL_TREE || ! tree_fits_uhwi_p (maxlen)) - return false; + { + if (fcode == BUILT_IN_STPNCPY_CHK && ignore) + { + /* If return value of __stpncpy_chk is ignored, + optimize into __strncpy_chk. */ + fn = builtin_decl_explicit (BUILT_IN_STRNCPY_CHK); + if (fn) + { + gimple *repl = gimple_build_call (fn, 4, dest, src, len, + size); + replace_call_with_call_and_fold (gsi, repl); + return true; + } + } + + return false; + } } else maxlen = len; @@ -3244,12 +3261,13 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, } /* If __builtin_st{r,p}ncpy_chk is used, assume st{r,p}ncpy is available. */ - fn = builtin_decl_explicit (fcode == BUILT_IN_STPNCPY_CHK + fn = builtin_decl_explicit (fcode == BUILT_IN_STPNCPY_CHK && !ignore ? BUILT_IN_STPNCPY : BUILT_IN_STRNCPY); if (!fn) return false; gimple *repl = gimple_build_call (fn, 3, dest, src, len); + dump_transformation (stmt, repl); replace_call_with_call_and_fold (gsi, repl); return true; } diff --git a/gcc/testsuite/gcc.dg/fold-stringops-1.c b/gcc/testsuite/gcc.dg/fold-stringops-1.c new file mode 100644 index 00000000000..712dd369e7c --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-stringops-1.c @@ -0,0 +1,23 @@ +/* { dg-do compile } */ +/* { dg-options "-O2 -fdump-tree-lower-details" } */ + +char dst[2048]; + +char * +copy1 (const char *src, int cond) +{ + __builtin___stpncpy_chk (dst, src, 42, __builtin_object_size (dst, 0)); + + return dst; +} + +char * +copy2 (void) +{ + __builtin___stpcpy_chk (dst, "Hello world", __builtin_object_size (dst, 0)); + + return dst; +} +/* { dg-final { scan-tree-dump "transformed __builtin___stpncpy_chk to __builtin_strncpy" "lower" } } */ +/* { dg-final { scan-tree-dump "transformed __builtin___stpcpy_chk to __builtin_strcpy" "lower" } } */ + From patchwork Thu Nov 11 19:41:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddhesh Poyarekar X-Patchwork-Id: 1554077 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=gotplt.org header.i=@gotplt.org header.a=rsa-sha1 header.s=gotplt.org header.b=YHVv1mRg; dkim-atps=neutral Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=8.43.85.97; helo=sourceware.org; envelope-from=gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org; receiver=) Received: from sourceware.org (ip-8-43-85-97.sourceware.org [8.43.85.97]) (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 bilbo.ozlabs.org (Postfix) with ESMTPS id 4HqsZp22lfz9s1l for ; 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d=gotplt.org; s=gotplt.org; t=1636659692; bh=Le2FZpEcvACUkJMfM7h2vcS9irY=; h=From:To:Cc:Subject:Date:Content-Transfer-Encoding; b=YHVv1mRgN9nBpoxkskrAUmKklJEoK4elgioQseF3CLcHlgdPEwjdlMsbqZP5FSGDH HR9G8l2WqfCrWLMvVMmWW//0fEviY0whcRxC7R7F8I6chI4/9hx93z8CU/OIEn7Aip 0+nLCNlZ5McDLs5PdmHsNgAjhCkPG7c2d8Sl3O9M= From: Siddhesh Poyarekar To: gcc-patches@gcc.gnu.org Subject: [PATCH 2/3] gimple-fold: Use ranges to simplify _chk calls Date: Fri, 12 Nov 2021 01:11:15 +0530 Message-Id: <20211111194116.1626980-3-siddhesh@gotplt.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211111194116.1626980-1-siddhesh@gotplt.org> References: <20211111194116.1626980-1-siddhesh@gotplt.org> MIME-Version: 1.0 X-Spam-Status: No, score=-3038.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, RCVD_IN_SBL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Sender: "Gcc-patches" Instead of comparing LEN and SIZE only if they are constants, use their ranges to decide if LEN will always be lower than or same as SIZE. This change ends up putting the stringop-overflow warning line number against the strcpy implementation, so adjust the warning check to be line number agnostic. gcc/ChangeLog: * gimple-fold.c (known_safe): New function. (gimple_fold_builtin_strncat_chk, gimple_fold_builtin_memory_chk, gimple_fold_builtin_stxcpy_chk, gimple_fold_builtin_stxncpy_chk, gimple_fold_builtin_snprintf_chk, gimple_fold_builtin_sprintf_chk): Use it. gcc/testsuite/ChangeLog: * gcc.dg/Wobjsize-1.c: Make warning change line agnostic. * gcc.dg/builtin-chk-fold.c: New test. Signed-off-by: Siddhesh Poyarekar --- gcc/gimple-fold.c | 216 +++++++++--------------- gcc/testsuite/gcc.dg/Wobjsize-1.c | 5 +- gcc/testsuite/gcc.dg/fold-stringops-2.c | 49 ++++++ 3 files changed, 132 insertions(+), 138 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/fold-stringops-2.c diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index 92e15784803..bcfd5d97feb 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -2031,6 +2031,28 @@ get_maxval_strlen (tree arg, strlen_range_kind rkind, tree *nonstr = NULL) return lendata.decl ? NULL_TREE : lendata.maxlen; } +/* Return true if LEN is known to be less than or equal to SIZE at compile time + and false otherwise. EXTRABYTE is true if there needs to be room for an + extra NUL byte at the end. */ + +static bool +known_safe (gimple *stmt, tree len, tree size, bool extrabyte = false) +{ + if (len == NULL_TREE) + return false; + + wide_int size_range[2]; + wide_int len_range[2]; + if (get_range (len, stmt, len_range) && get_range (size, stmt, size_range)) + { + if (extrabyte) + return wi::ltu_p (len_range[1], size_range[0]); + else + return wi::leu_p (len_range[1], size_range[0]); + } + + return false; +} /* Fold function call to builtin strcpy with arguments DEST and SRC. If LEN is not NULL, it represents the length of the string to be @@ -2566,16 +2588,10 @@ gimple_fold_builtin_strncat_chk (gimple_stmt_iterator *gsi) return true; } - if (! tree_fits_uhwi_p (size)) - return false; - if (! integer_all_onesp (size)) { tree src_len = c_strlen (src, 1); - if (src_len - && tree_fits_uhwi_p (src_len) - && tree_fits_uhwi_p (len) - && ! tree_int_cst_lt (len, src_len)) + if (known_safe (stmt, src_len, len)) { /* If LEN >= strlen (SRC), optimize into __strcat_chk. */ fn = builtin_decl_explicit (BUILT_IN_STRCAT_CHK); @@ -3024,39 +3040,24 @@ gimple_fold_builtin_memory_chk (gimple_stmt_iterator *gsi, } } - if (! tree_fits_uhwi_p (size)) - return false; - tree maxlen = get_maxval_strlen (len, SRK_INT_VALUE); - if (! integer_all_onesp (size)) + if (! integer_all_onesp (size) + && !known_safe (stmt, len, size) && !known_safe (stmt, maxlen, size)) { - if (! tree_fits_uhwi_p (len)) + /* MAXLEN and LEN both cannot be proved to be less than SIZE, at + least try to optimize (void) __mempcpy_chk () into + (void) __memcpy_chk () */ + if (fcode == BUILT_IN_MEMPCPY_CHK && ignore) { - /* If LEN is not constant, try MAXLEN too. - For MAXLEN only allow optimizing into non-_ocs function - if SIZE is >= MAXLEN, never convert to __ocs_fail (). */ - if (maxlen == NULL_TREE || ! tree_fits_uhwi_p (maxlen)) - { - if (fcode == BUILT_IN_MEMPCPY_CHK && ignore) - { - /* (void) __mempcpy_chk () can be optimized into - (void) __memcpy_chk (). */ - fn = builtin_decl_explicit (BUILT_IN_MEMCPY_CHK); - if (!fn) - return false; + fn = builtin_decl_explicit (BUILT_IN_MEMCPY_CHK); + if (!fn) + return false; - gimple *repl = gimple_build_call (fn, 4, dest, src, len, size); - replace_call_with_call_and_fold (gsi, repl); - return true; - } - return false; - } + gimple *repl = gimple_build_call (fn, 4, dest, src, len, size); + replace_call_with_call_and_fold (gsi, repl); + return true; } - else - maxlen = len; - - if (tree_int_cst_lt (size, maxlen)) - return false; + return false; } fn = NULL_TREE; @@ -3139,61 +3140,48 @@ gimple_fold_builtin_stxcpy_chk (gimple_stmt_iterator *gsi, return true; } - if (! tree_fits_uhwi_p (size)) - return false; - tree maxlen = get_maxval_strlen (src, SRK_STRLENMAX); if (! integer_all_onesp (size)) { len = c_strlen (src, 1); - if (! len || ! tree_fits_uhwi_p (len)) + if (!known_safe (stmt, len, size, true) + && !known_safe (stmt, maxlen, size, true)) { - /* If LEN is not constant, try MAXLEN too. - For MAXLEN only allow optimizing into non-_ocs function - if SIZE is >= MAXLEN, never convert to __ocs_fail (). */ - if (maxlen == NULL_TREE || ! tree_fits_uhwi_p (maxlen)) + if (fcode == BUILT_IN_STPCPY_CHK) { - if (fcode == BUILT_IN_STPCPY_CHK) - { - if (! ignore) - return false; - - /* If return value of __stpcpy_chk is ignored, - optimize into __strcpy_chk. */ - fn = builtin_decl_explicit (BUILT_IN_STRCPY_CHK); - if (!fn) - return false; - - gimple *repl = gimple_build_call (fn, 3, dest, src, size); - replace_call_with_call_and_fold (gsi, repl); - return true; - } - - if (! len || TREE_SIDE_EFFECTS (len)) + if (! ignore) return false; - /* If c_strlen returned something, but not a constant, - transform __strcpy_chk into __memcpy_chk. */ - fn = builtin_decl_explicit (BUILT_IN_MEMCPY_CHK); + /* If return value of __stpcpy_chk is ignored, + optimize into __strcpy_chk. */ + fn = builtin_decl_explicit (BUILT_IN_STRCPY_CHK); if (!fn) return false; - gimple_seq stmts = NULL; - len = force_gimple_operand (len, &stmts, true, NULL_TREE); - len = gimple_convert (&stmts, loc, size_type_node, len); - len = gimple_build (&stmts, loc, PLUS_EXPR, size_type_node, len, - build_int_cst (size_type_node, 1)); - gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT); - gimple *repl = gimple_build_call (fn, 4, dest, src, len, size); + gimple *repl = gimple_build_call (fn, 3, dest, src, size); replace_call_with_call_and_fold (gsi, repl); return true; } - } - else - maxlen = len; - if (! tree_int_cst_lt (maxlen, size)) - return false; + if (! len || TREE_SIDE_EFFECTS (len)) + return false; + + /* If c_strlen returned something, but not provably less than size, + transform __strcpy_chk into __memcpy_chk. */ + fn = builtin_decl_explicit (BUILT_IN_MEMCPY_CHK); + if (!fn) + return false; + + gimple_seq stmts = NULL; + len = force_gimple_operand (len, &stmts, true, NULL_TREE); + len = gimple_convert (&stmts, loc, size_type_node, len); + len = gimple_build (&stmts, loc, PLUS_EXPR, size_type_node, len, + build_int_cst (size_type_node, 1)); + gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT); + gimple *repl = gimple_build_call (fn, 4, dest, src, len, size); + replace_call_with_call_and_fold (gsi, repl); + return true; + } } /* If __builtin_st{r,p}cpy_chk is used, assume st{r,p}cpy is available. */ @@ -3223,41 +3211,23 @@ gimple_fold_builtin_stxncpy_chk (gimple_stmt_iterator *gsi, bool ignore = gimple_call_lhs (stmt) == NULL_TREE; tree fn; - if (! tree_fits_uhwi_p (size)) - return false; - tree maxlen = get_maxval_strlen (len, SRK_INT_VALUE); - if (! integer_all_onesp (size)) + if (! integer_all_onesp (size) + && !known_safe (stmt, len, size) && !known_safe (stmt, maxlen, size)) { - if (! tree_fits_uhwi_p (len)) + if (fcode == BUILT_IN_STPNCPY_CHK && ignore) { - /* If LEN is not constant, try MAXLEN too. - For MAXLEN only allow optimizing into non-_ocs function - if SIZE is >= MAXLEN, never convert to __ocs_fail (). */ - if (maxlen == NULL_TREE || ! tree_fits_uhwi_p (maxlen)) + /* If return value of __stpncpy_chk is ignored, + optimize into __strncpy_chk. */ + fn = builtin_decl_explicit (BUILT_IN_STRNCPY_CHK); + if (fn) { - if (fcode == BUILT_IN_STPNCPY_CHK && ignore) - { - /* If return value of __stpncpy_chk is ignored, - optimize into __strncpy_chk. */ - fn = builtin_decl_explicit (BUILT_IN_STRNCPY_CHK); - if (fn) - { - gimple *repl = gimple_build_call (fn, 4, dest, src, len, - size); - replace_call_with_call_and_fold (gsi, repl); - return true; - } - } - - return false; + gimple *repl = gimple_build_call (fn, 4, dest, src, len, size); + replace_call_with_call_and_fold (gsi, repl); + return true; } } - else - maxlen = len; - - if (tree_int_cst_lt (size, maxlen)) - return false; + return false; } /* If __builtin_st{r,p}ncpy_chk is used, assume st{r,p}ncpy is available. */ @@ -3377,27 +3347,11 @@ gimple_fold_builtin_snprintf_chk (gimple_stmt_iterator *gsi, size = gimple_call_arg (stmt, 3); fmt = gimple_call_arg (stmt, 4); - if (! tree_fits_uhwi_p (size)) + tree maxlen = get_maxval_strlen (len, SRK_INT_VALUE); + if (! integer_all_onesp (size) + && !known_safe (stmt, len, size) && !known_safe (stmt, maxlen, size)) return false; - if (! integer_all_onesp (size)) - { - tree maxlen = get_maxval_strlen (len, SRK_INT_VALUE); - if (! tree_fits_uhwi_p (len)) - { - /* If LEN is not constant, try MAXLEN too. - For MAXLEN only allow optimizing into non-_ocs function - if SIZE is >= MAXLEN, never convert to __ocs_fail (). */ - if (maxlen == NULL_TREE || ! tree_fits_uhwi_p (maxlen)) - return false; - } - else - maxlen = len; - - if (tree_int_cst_lt (size, maxlen)) - return false; - } - if (!init_target_chars ()) return false; @@ -3456,9 +3410,6 @@ gimple_fold_builtin_sprintf_chk (gimple_stmt_iterator *gsi, size = gimple_call_arg (stmt, 2); fmt = gimple_call_arg (stmt, 3); - if (! tree_fits_uhwi_p (size)) - return false; - len = NULL_TREE; if (!init_target_chars ()) @@ -3485,20 +3436,13 @@ gimple_fold_builtin_sprintf_chk (gimple_stmt_iterator *gsi, { arg = gimple_call_arg (stmt, 4); if (POINTER_TYPE_P (TREE_TYPE (arg))) - { - len = c_strlen (arg, 1); - if (! len || ! tree_fits_uhwi_p (len)) - len = NULL_TREE; - } + len = c_strlen (arg, 1); } } } - if (! integer_all_onesp (size)) - { - if (! len || ! tree_int_cst_lt (len, size)) - return false; - } + if (! integer_all_onesp (size) && !known_safe (stmt, len, size, true)) + return false; /* Only convert __{,v}sprintf_chk to {,v}sprintf if flag is 0 or if format doesn't contain % chars or is "%s". */ diff --git a/gcc/testsuite/gcc.dg/Wobjsize-1.c b/gcc/testsuite/gcc.dg/Wobjsize-1.c index 2bd2f93897b..988b8bcbf35 100644 --- a/gcc/testsuite/gcc.dg/Wobjsize-1.c +++ b/gcc/testsuite/gcc.dg/Wobjsize-1.c @@ -7,11 +7,12 @@ char buf[6]; int main(int argc, char **argv) { - strcpy (buf,"hello "); /* { dg-warning "\\\[-Wstringop-overflow" } */ + strcpy (buf,"hello "); return 0; } -/* { dg-message "file included" "included" { target *-*-* } 0 } +/* { dg-warning "\\\[-Wstringop-overflow" "warning" { target *-*-* } 0 } + { dg-message "file included" "included" { target *-*-* } 0 } { dg-message "inlined from" "inlined" { target *-*-* } 0 } The test might emit two warnings, one for the strcpy call and diff --git a/gcc/testsuite/gcc.dg/fold-stringops-2.c b/gcc/testsuite/gcc.dg/fold-stringops-2.c new file mode 100644 index 00000000000..0b415dfaf57 --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-stringops-2.c @@ -0,0 +1,49 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +#define bos(__d) __builtin_object_size ((__d), 0) + +char * +safe1 (const char *src, int cond, __SIZE_TYPE__ len) +{ + char *dst; + + if (cond) + dst = __builtin_malloc (1024); + else + dst = __builtin_malloc (2048); + + len = len > 2048 ? 2048 : len; + + return __builtin___memcpy_chk (dst, src, len, bos (dst)); +} + +char * +safe2 (const char *src, int cond, unsigned char len) +{ + char *dst; + + if (cond) + dst = __builtin_malloc (1024); + else + dst = __builtin_malloc (2048); + + return __builtin___strncpy_chk (dst, src, len, bos (dst)); +} + +int +safe3 (const char *src, int cond, unsigned char len) +{ + char *dst; + + if (cond) + dst = __builtin_malloc (1024); + else + dst = __builtin_malloc (2048); + + return __builtin___snprintf_chk (dst, len, 0, bos (dst), "%s", src); +} + +/* { dg-final { scan-assembler-not "__memcpy_chk" } } */ +/* { dg-final { scan-assembler-not "__strncpy_chk" } } */ +/* { dg-final { scan-assembler-not "__snprintf_chk" } } */ From patchwork Thu Nov 11 19:41:16 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Siddhesh Poyarekar X-Patchwork-Id: 1554076 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: bilbo.ozlabs.org; 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Thu, 11 Nov 2021 11:41:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; d=gotplt.org; s=gotplt.org; t=1636659694; bh=5dBloBPaUeZbmeCFwNFeYERduSU=; h=From:To:Cc:Subject:Date:Content-Transfer-Encoding; b=wukLBvV9gZbduNAVmosFhxM1qTfw8iNfri1ZEm16FCnGqmVM63fFI+zjfMwv4pG+k I/yBGGILtvexEBE4syqtKtcGH5hpor9h7Ai13xAaX3HHdm9x61++mRtyY9qRrYmx58 vYN8AhOlRxtPN7bX4qAHBXVnbEO1ZeH+112Ch7IM= From: Siddhesh Poyarekar To: gcc-patches@gcc.gnu.org Subject: [PATCH 3/3] gimple-fold: Use ranges to simplify strncat and snprintf Date: Fri, 12 Nov 2021 01:11:16 +0530 Message-Id: <20211111194116.1626980-4-siddhesh@gotplt.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20211111194116.1626980-1-siddhesh@gotplt.org> References: <20211111194116.1626980-1-siddhesh@gotplt.org> MIME-Version: 1.0 X-Spam-Status: No, score=-3038.0 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_BARRACUDACENTRAL, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H2, RCVD_IN_SBL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: gcc-patches-bounces+incoming=patchwork.ozlabs.org@gcc.gnu.org Sender: "Gcc-patches" Remove the warnings for strncat since it is already handled (and even the error messages look identical) in gimple-ssa-warn-access. Instead, use len range to determine if it is within bounds of source and destination and simplify it to strcat if it's safe. Likewise for snprintf, use ranges to determine if it can be transformed to strcpy. gcc/ChangeLog: * gimple-fold.c (gimple_fold_builtin_strncat): Remove warnings and use ranges to determine if it is safe to transform to strcat. (gimple_fold_builtin_snprintf): Likewise. gcc/testsuite/ChangeLog: * gcc.dg/fold-stringops-2.c: Define size_t. (safe1): Adjust. (safe4): New test. * gcc.dg/fold-stringops-3.c: New test. Signed-off-by: Siddhesh Poyarekar --- gcc/gimple-fold.c | 76 +++++-------------------- gcc/testsuite/gcc.dg/fold-stringops-2.c | 16 +++++- gcc/testsuite/gcc.dg/fold-stringops-3.c | 18 ++++++ 3 files changed, 47 insertions(+), 63 deletions(-) create mode 100644 gcc/testsuite/gcc.dg/fold-stringops-3.c diff --git a/gcc/gimple-fold.c b/gcc/gimple-fold.c index bcfd5d97feb..3112b86c2f7 100644 --- a/gcc/gimple-fold.c +++ b/gcc/gimple-fold.c @@ -2485,72 +2485,29 @@ gimple_fold_builtin_strncat (gimple_stmt_iterator *gsi) tree dst = gimple_call_arg (stmt, 0); tree src = gimple_call_arg (stmt, 1); tree len = gimple_call_arg (stmt, 2); - - const char *p = c_getstr (src); + tree src_len = c_strlen (src, 1); /* If the requested length is zero, or the src parameter string length is zero, return the dst parameter. */ - if (integer_zerop (len) || (p && *p == '\0')) + if (integer_zerop (len) || (src_len && integer_zerop (src_len))) { replace_call_with_value (gsi, dst); return true; } - if (TREE_CODE (len) != INTEGER_CST || !p) - return false; - - unsigned srclen = strlen (p); - - int cmpsrc = compare_tree_int (len, srclen); - /* Return early if the requested len is less than the string length. Warnings will be issued elsewhere later. */ - if (cmpsrc < 0) + if (!known_safe (stmt, src_len, len)) return false; unsigned HOST_WIDE_INT dstsize; - bool nowarn = warning_suppressed_p (stmt, OPT_Wstringop_overflow_); - - if (!nowarn && compute_builtin_object_size (dst, 1, &dstsize)) - { - int cmpdst = compare_tree_int (len, dstsize); - - if (cmpdst >= 0) - { - tree fndecl = gimple_call_fndecl (stmt); - - /* Strncat copies (at most) LEN bytes and always appends - the terminating NUL so the specified bound should never - be equal to (or greater than) the size of the destination. - If it is, the copy could overflow. */ - location_t loc = gimple_location (stmt); - nowarn = warning_at (loc, OPT_Wstringop_overflow_, - cmpdst == 0 - ? G_("%qD specified bound %E equals " - "destination size") - : G_("%qD specified bound %E exceeds " - "destination size %wu"), - fndecl, len, dstsize); - if (nowarn) - suppress_warning (stmt, OPT_Wstringop_overflow_); - } - } - - if (!nowarn && cmpsrc == 0) - { - tree fndecl = gimple_call_fndecl (stmt); - location_t loc = gimple_location (stmt); - - /* To avoid possible overflow the specified bound should also - not be equal to the length of the source, even when the size - of the destination is unknown (it's not an uncommon mistake - to specify as the bound to strncpy the length of the source). */ - if (warning_at (loc, OPT_Wstringop_overflow_, - "%qD specified bound %E equals source length", - fndecl, len)) - suppress_warning (stmt, OPT_Wstringop_overflow_); - } + /* Likewise, bail out from the transformation if we're unable to determine + the destination size. Warnings will be issued elsewhere later. */ + if (!compute_builtin_object_size (dst, 1, &dstsize) + || !known_safe (stmt, len, build_int_cstu (TREE_TYPE (len), dstsize), + true)) + return false; tree fn = builtin_decl_implicit (BUILT_IN_STRCAT); @@ -3626,10 +3583,6 @@ gimple_fold_builtin_snprintf (gimple_stmt_iterator *gsi) if (gimple_call_num_args (stmt) == 4) orig = gimple_call_arg (stmt, 3); - if (!tree_fits_uhwi_p (destsize)) - return false; - unsigned HOST_WIDE_INT destlen = tree_to_uhwi (destsize); - /* Check whether the format is a literal string constant. */ fmt_str = c_getstr (fmt); if (fmt_str == NULL) @@ -3649,6 +3602,8 @@ gimple_fold_builtin_snprintf (gimple_stmt_iterator *gsi) if (orig) return false; + tree len = build_int_cstu (TREE_TYPE (destsize), strlen (fmt_str)); + /* We could expand this as memcpy (str, fmt, cst - 1); str[cst - 1] = '\0'; or to @@ -3656,8 +3611,7 @@ gimple_fold_builtin_snprintf (gimple_stmt_iterator *gsi) but in the former case that might increase code size and in the latter case grow .rodata section too much. So punt for now. */ - size_t len = strlen (fmt_str); - if (len >= destlen) + if (!known_safe (stmt, len, destsize, true)) return false; gimple_seq stmts = NULL; @@ -3666,7 +3620,7 @@ gimple_fold_builtin_snprintf (gimple_stmt_iterator *gsi) if (tree lhs = gimple_call_lhs (stmt)) { repl = gimple_build_assign (lhs, - build_int_cst (TREE_TYPE (lhs), len)); + fold_convert (TREE_TYPE (lhs), len)); gimple_seq_add_stmt_without_update (&stmts, repl); gsi_replace_with_seq_vops (gsi, stmts); /* gsi now points at the assignment to the lhs, get a @@ -3697,8 +3651,6 @@ gimple_fold_builtin_snprintf (gimple_stmt_iterator *gsi) return false; tree orig_len = get_maxval_strlen (orig, SRK_STRLEN); - if (!orig_len || TREE_CODE (orig_len) != INTEGER_CST) - return false; /* We could expand this as memcpy (str1, str2, cst - 1); str1[cst - 1] = '\0'; @@ -3707,7 +3659,7 @@ gimple_fold_builtin_snprintf (gimple_stmt_iterator *gsi) but in the former case that might increase code size and in the latter case grow .rodata section too much. So punt for now. */ - if (compare_tree_int (orig_len, destlen) >= 0) + if (!known_safe (stmt, orig_len, destsize, true)) return false; /* Convert snprintf (str1, cst, "%s", str2) into diff --git a/gcc/testsuite/gcc.dg/fold-stringops-2.c b/gcc/testsuite/gcc.dg/fold-stringops-2.c index 0b415dfaf57..ac7d29eac50 100644 --- a/gcc/testsuite/gcc.dg/fold-stringops-2.c +++ b/gcc/testsuite/gcc.dg/fold-stringops-2.c @@ -1,10 +1,12 @@ /* { dg-do compile } */ /* { dg-options "-O2" } */ +typedef __SIZE_TYPE__ size_t; + #define bos(__d) __builtin_object_size ((__d), 0) char * -safe1 (const char *src, int cond, __SIZE_TYPE__ len) +safe1 (const char *src, int cond, size_t len) { char *dst; @@ -44,6 +46,18 @@ safe3 (const char *src, int cond, unsigned char len) return __builtin___snprintf_chk (dst, len, 0, bos (dst), "%s", src); } +char dst[1024]; + +void +safe4 (size_t len) +{ + len = len > sizeof (dst) - 1 ? sizeof (dst) - 1 : len; + len = len < sizeof (dst) / 2 ? sizeof (dst) / 2 : len; + + __builtin_strncat (dst, "hello", len); +} + /* { dg-final { scan-assembler-not "__memcpy_chk" } } */ /* { dg-final { scan-assembler-not "__strncpy_chk" } } */ /* { dg-final { scan-assembler-not "__snprintf_chk" } } */ +/* { dg-final { scan-assembler-not "strncat" } } */ diff --git a/gcc/testsuite/gcc.dg/fold-stringops-3.c b/gcc/testsuite/gcc.dg/fold-stringops-3.c new file mode 100644 index 00000000000..ae2efbf9967 --- /dev/null +++ b/gcc/testsuite/gcc.dg/fold-stringops-3.c @@ -0,0 +1,18 @@ +/* { dg-do compile } */ +/* { dg-options "-O2" } */ + +typedef __SIZE_TYPE__ size_t; + +char dst[1024]; + +void +safe1 (size_t len) +{ + len = len > sizeof (dst) ? sizeof (dst) : len; + len = len < sizeof (dst) / 2 ? sizeof (dst) / 2 : len; + + __builtin_snprintf (dst, len, "hello"); + __builtin_snprintf (dst + 5, len, "%s", " world"); +} + +/* { dg-final { scan-assembler-not "snprintf" } } */