On Sun, Mar 29, 2020 at 05:01:39PM -0400, Jeffrey Walton via Gcc-help wrote:
> I'm having trouble with floating point arithmetic and division by 0.
> Undefined behavior sanitizer flags a division by 0 is a runtime error.
int f(int x) { return x / 0; }
float g(float x) { return x / 0; }
This actually warns during build for both functions:
$ gcc -Wall -W -O2 -fsanitize=undefined dz.c
dz.c: In function 'f':
dz.c:1:25: warning: division by zero [-Wdiv-by-zero]
1 | int f(int x) { return x / 0; }
| ^
dz.c: In function 'g':
dz.c:2:29: warning: division by zero [-Wdiv-by-zero]
2 | float g(float x) { return x / 0; }
| ^
but only f does anything with ubsan, as it should. (Please open a PR
for the warning:
'-Wno-div-by-zero'
Do not warn about compile-time integer division by zero.
Floating-point division by zero is not warned about, as it can be a
legitimate way of obtaining infinities and NaNs.
We clearly have a floating point division here.)
What do you do to see ubsan misfire?
Segher
