math: trigonometric argument reduction fails for huge arguments #6794
Description
Here is a test program http://play.golang.org/p/lROOy0Hekp The value 2^120 is exactly represented as a float64. A different, incorrect answer is returned by 8g (0.4779...). The right answer is returned by gccgo on an 64-bit x86 (-0.9258...). The wrong answer is returned by gccgo on 32-bit x86 where the cos function doesn't seem to compute anything and behaves like the identity function.