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? -- H.J.