GCC problem with raw double type comparisons

Question

I have the following bit of code, however when compiling it with GCC 4.4 with various optimization flags I get some unexpected results when its run.

#include         


        

Answer 1

The width of the floating point registers in x86 is different from the width of the double in RAM. Therefore comparisons may succeed or fail depending entirely on how the compiler decides to optimize the loads of floating point values.