On Tue, Aug 22, 2017 at 5:07 AM, Stefan Liebler wrote: > 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? > Here is the updated patch. I added if (outer == 0) break; at the end of loop. -- H.J.