How to know or specify the instrcution set (X87, SSE, or AVX) that being used

Hi,

I am compiling my code using ifort 13.1.0 and running it on an Xeon Intel 8-Core 64-bit E5-processor. 
The platform supports X87, SSE and AVX. Now I am using PAPI to measure the floating point instructions
and later may do some vectorization work. My questions are:

1. Both X87 and SSE can do scalar floating point operations. Which one will the compiler choose to
use? Is there a switch to control? I can measure the scalar FLOP from SSE but I don't have a counter for X87.

2. Both SSE and AVX can do vector floating point operations. Which one will the compiler choose to

use? Is there a switch to control?

Thanks for your time and help.

Happy Thanksgiving!

Best regards,
   Wentao