Fail to compare float number with infinity about emscripten

[kripken]

Could be undefined behavior. Try with -fsanitize=undefined.

If it's not that, please reduce this to a small testcase that is simple to compile (without gtest and other external things).

[pgeorge1324]

@kripken

Could be undefined behavior. Try with -fsanitize=undefined.

If it's not that, please reduce this to a small testcase that is simple to compile (without gtest and other external things).

I wrote a testcase with minimal external things, finally i found the compile option -ffast-math used in my project is the main crime.
I know it is a compile option in gcc, does new emscripten has some similiar compile option?

#include <iostream>
#include <limits>

static const float M_INF = std::numeric_limits<float>::infinity();

int main()
{
    std::cout << std::isinf(std::numeric_limits<float>::infinity()) << std::endl;
    std::cout << std::isinf(M_INF) << std::endl;
    std::cout << (M_INF == std::numeric_limits<float>::infinity()) << std::endl;

    std::cout << "Hello, World!" << std::endl;
    return 0;
}

>> em++ .\main.cpp -ffast-math -O3 -o test.js
>> node test.js
0
0
0
Hello, World!
>> em++ .\main.cpp -O3 -o test.js            
>> node test.js                  
1
1
1
Hello, World!

[pgeorge1324]

I solved it with compile option -fhonor-infinities
Clang manual has more detail information about it: clang manual

>>em++ .\main.cpp -ffast-math -fhonor-infinities -O3 -o test.js
>> node test.js                                                 
1
1
1
Hello, World!

Thanks for your reply @kripken