[Bug middle-end/102126] Wrong optimization of FP multiplication and division by 1 and -1 with -ftrapping-math when an underflow is possible

[vincent-gcc at vinc17 dot net via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102126

--- Comment #7 from Vincent Lefèvre <vincent-gcc at vinc17 dot net> ---
According to the current documentation, -f(no-)trapping-math is only about
traps, not flags.

And Glibc provides functions feenableexcept and fedisableexcept to enable and
disable traps, so that their possible existence needs to be supported.