Please try compiling and executing the attached test program on Linux.
For me, it produces the correct results:

Negative infinity 32 = -inf
Positive infinity 32 = inf
Not a number 32 = nan
Negative infinity 64 = -inf
Positive infinity 64 = inf
Not a number 64 = nan

I'm curious to see whether it produces correct results for you with -O3.

I used the following command line:

  gcc -Wall -O3 -I /home/eiffel/Eiffel13.11.93542/studio/spec/linux-x86/include -o inline_bug -m32 inline_bug.c