get the number of spilling

[kito]

Hello everybody:
I want to count the number of spilling.
I have try to compile file with -fdump-rtl-ira
And then use `grep Spilling *.ira | wc -l`
Does it's right way to get the number of spilling?

I am confuse about  the result data because the number of spilling is
-O1 < -O2 < -O3.

Benchmark : SPEC2000
target: arm-linux-elf
gcc version : 4.4.0

                -O1     -O2     -O3
164.zip         1338    1407    3033
181.mcf         305     362     603
186.crafty      4888    7159    7878