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: 47500 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id EA06F385AC38 for ; Thu, 11 Nov 2021 19:43:16 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from caracal.ash.relay.mailchannels.net (caracal.ash.relay.mailchannels.net [23.83.222.30]) by sourceware.org (Postfix) with ESMTPS id D87B7385AC33 for ; Thu, 11 Nov 2021 19:41:36 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org D87B7385AC33 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 2DB5B9222CD; Thu, 11 Nov 2021 19:41:33 +0000 (UTC) Received: from pdx1-sub0-mail-a304.dreamhost.com (100-96-99-57.trex.outbound.svc.cluster.local [100.96.99.57]) (Authenticated sender: dreamhost) by relay.mailchannels.net (Postfix) with ESMTPA id 59D949220E6; Thu, 11 Nov 2021 19:41:32 +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 100.96.99.57 (trex/6.4.3); Thu, 11 Nov 2021 19:41:33 +0000 X-MC-Relay: Neutral X-MailChannels-SenderId: dreamhost|x-authsender|siddhesh@gotplt.org X-MailChannels-Auth-Id: dreamhost X-Harbor-Language: 3accfb1a10202174_1636659692634_3248925865 X-MC-Loop-Signature: 1636659692634:2373446361 X-MC-Ingress-Time: 1636659692633 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 4HqsXp2Xkzz23; Thu, 11 Nov 2021 11:41:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha1; c=relaxed/relaxed; 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+patchwork=sourceware.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" } } */