From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 121266 invoked by alias); 21 Aug 2017 13:49:02 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Received: (qmail 95868 invoked by uid 89); 21 Aug 2017 13:48:38 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-24.4 required=5.0 tests=AWL,BAYES_00,GIT_PATCH_0,GIT_PATCH_1,GIT_PATCH_2,GIT_PATCH_3,KAM_LAZY_DOMAIN_SECURITY,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.2 spammy= X-HELO: mx0a-001b2d01.pphosted.com Subject: Re: [PATCH] string/stratcliff.c: Replace int with size_t [BZ #21982] To: libc-alpha@sourceware.org References: <20170820171713.GA19531@gmail.com> From: Stefan Liebler Date: Mon, 21 Aug 2017 13:49:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20170820171713.GA19531@gmail.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 17082113-0020-0000-0000-000003B01CF6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17082113-0021-0000-0000-0000423F912B Message-Id: <25604b34-7afb-7007-4ea8-3add9963d4b4@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-08-21_09:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=1 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1708210219 X-SW-Source: 2017-08/txt/msg00976.txt.bz2 On 08/20/2017 07:17 PM, H.J. Lu wrote: > Fix GCC 7 errors when string/stratcliff.c is compiled with -O3: > > stratcliff.c: In function ‘do_test’: > cc1: error: assuming signed overflow does not occur when assuming that (X - c) <= X is always true [-Werror=strict-overflow] > > OK for master? > > H.J. > --- > [BZ #21982] > * string/stratcliff.c (do_test): Declare size, nchars, inner, > middle and outer with size_t instead of int. Repleace %d with > %Zd in printf. > --- > string/stratcliff.c | 72 ++++++++++++++++++++++++++--------------------------- > 1 file changed, 36 insertions(+), 36 deletions(-) > > diff --git a/string/stratcliff.c b/string/stratcliff.c > index e28b0c5058..ae780379cb 100644 > --- a/string/stratcliff.c > +++ b/string/stratcliff.c > @@ -58,8 +58,8 @@ > int > do_test (void) > { > - int size = sysconf (_SC_PAGESIZE); > - int nchars = size / sizeof (CHAR); > + size_t size = sysconf (_SC_PAGESIZE); > + size_t nchars = size / sizeof (CHAR); > CHAR *adr; > CHAR *dest; > int result = 0; > @@ -80,7 +80,7 @@ do_test (void) > } > else > { > - int inner, middle, outer; > + size_t inner, middle, outer; > > mprotect (adr, size, PROT_NONE); > mprotect (adr + 2 * nchars, size, PROT_NONE); > @@ -101,7 +101,7 @@ do_test (void) > > if (STRLEN (&adr[outer]) != (size_t) (inner - outer)) > { > - printf ("%s flunked for outer = %d, inner = %d\n", > + printf ("%s flunked for outer = %Zd, inner = %Zd\n", > STRINGIFY (STRLEN), outer, inner); > result = 1; > } > { > - printf ("%s flunked for outer = %d, middle = %d\n", > + printf ("%s flunked for outer = %Zd, middle = %Zd\n", > STRINGIFY (rawmemchr), outer, middle); > result = 1; > } > Hi H.J. Lu, I've applied your patch and the warnings does not occur anymore on s390. The outer loops of the string tests are all using the following: size_t nchars, outer; for (outer = nchars - 1; outer >= MAX (0, nchars - 128); --outer) I think we can assume, that nchars is always > 128 as it is derived by the pagesize. But if nchars would be equal to 128, this would result in an infinite loop (outer >= 0)? If nchars would be less than 128, the tests would be skipped. Should we add a check that nchars > 128 at the beginning and replace the "MAX (0, nchars - 128)" with only "nchars - 128"? Bye, Stefan