Great news! Thanks for investigating.
On Tue, Mar 1, 2022 at 9:49 PM Александр Гурьянов <[email protected]>
wrote:
> Okay I found the answer it's a result of using optimization flags -Oz
> --ffast-math. If you remove one of it - works correctly. Also behavior is
> exactly same in clang++, so I think there is no error from emscripten.
> My last test case:
>
> #include <cstdio>
> #include <cmath>
> #include <limits>
>
> int main(int argc, char **argv) {
> float val = std::numeric_limits<float>::quiet_NaN();
>
> printf("val '%.2f', isnan:%s\n", val,
> std::isnan(val) ? "yes" : "no");
>
> return 0;
> }
>
>
>
> ср, 2 мар. 2022 г. в 08:46, Александр Гурьянов <[email protected]>:
>
>> I tried to do this but in empty project it works correctly. I converted
>> the float to int32_t like this:
>>
>> int32_t* val = (int32_t) &res;
>> printf("%d\n", *val);
>>
>> and the number was 2143289344 <(214)%20328-9344>, I created testcase:
>>
>> #include <cmath>
>> #include <cstdio>
>>
>> int main(int argc, char** argv) {
>> int32_t nan = 2143289344 <(214)%20328-9344>;
>> float* val = (float *) &nan;
>>
>> printf("val '%.2f', isnan:%s, isinf:%s\n", *val,
>> std::isnan(*val) ? "yes" : "no",
>> std::isinf(*val) ? "yes" : "no");
>>
>> return 0;
>> }
>>
>> but it works correctly:
>>
>> val 'nan', isnan: yes, isinf: no
>>
>> Moreover in native build of project there is no NAN in problem place, it
>> appears only in emscripten build. So, probably error happens somewhere
>> else... Trying to understand.
>>
>> ср, 2 мар. 2022 г. в 00:18, 'Sam Clegg' via emscripten-discuss <
>> [email protected]>:
>>
>>> Perhaps if you print the actual bitpattern at the point of failure you
>>> can use that to create a repro case? Without a repro case I think this
>>> will be hard to make progress on. Once you have a repro please open an bug
>>> report on github.
>>>
>>> chers,
>>> sam
>>>
>>>
>>> On Tue, Mar 1, 2022 at 8:38 AM Александр Гурьянов <[email protected]>
>>> wrote:
>>>
>>>> Hi, I faced problem that std::isnan return false for NAN. I added this
>>>> debug printf to my project:
>>>>
>>>> printf("res %.2f %s %s\n", res,
>>>> std::isnan(res) ? "isnan" : "notnan",
>>>> std::isinf(res) ? "isinf" : "notinf");
>>>>
>>>> and when res is NAN, output is following:
>>>>
>>>> res nan notnan notinf
>>>>
>>>> I tried to make a simple test case, but in test case it works fine. So,
>>>> I think this is a sort of UB, but I run project with valgrind - no errors.
>>>> I tried -s ASSERTIONS=1 -s SAFE_HEAP=2, also no errors.
>>>>
>>>> Any suggestions what it can be?
>>>>
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>>>>
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