From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 107884 invoked by alias); 22 Aug 2017 12:07:12 -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 107790 invoked by uid 89); 22 Aug 2017 12:07:11 -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 From: Stefan Liebler Subject: Re: [PATCH] string/stratcliff.c: Replace int with size_t [BZ #21982] To: "H.J. Lu" Cc: GNU C Library References: <20170820171713.GA19531@gmail.com> <25604b34-7afb-7007-4ea8-3add9963d4b4@linux.vnet.ibm.com> Date: Tue, 22 Aug 2017 12:07:00 -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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 x-cbid: 17082212-0040-0000-0000-000003F26713 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17082212-0041-0000-0000-000020928CEF Message-Id: <10fd8eb0-0f53-9d4b-dcd2-694a1878c994@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-08-22_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1708220189 X-SW-Source: 2017-08/txt/msg01049.txt.bz2 On 08/22/2017 01:05 AM, H.J. Lu wrote: > On Mon, Aug 21, 2017 at 8:41 AM, Stefan Liebler wrote: >> On 08/21/2017 04:53 PM, H.J. Lu wrote: >>> >>> On Mon, Aug 21, 2017 at 6:48 AM, Stefan Liebler >>> wrote: >>>> >>>> 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. >>> >>> >>> Great. >>> >>>> 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"? >>> >>> >>> This is a separate issue beyond BZ #21982. >>> >>> >> Your patch is introducing this behaviour. >> Before your patch, nchars and outer was an int and the for-loop-condition >> "outer >= MAX (0, nchars - 128)" does not lead to an infinite loop or to >> skipping the test if nchars <= 128. >> > > How about this patch? > This solves the cases if nchars < 128. But if nchars == 128, then the condition of the for-loop is "size_t outer >= 0", which is always true. Could we check once if nchars > 128 and exit the test with an error if nchars is <= 128? Are there architectures where the page size is < 4096? Or where wchar_t > 4byte? Bye Stefan