[m5-dev] floorLog2()

[Nilay Vaish]

I was looking at the implementation of floorLog2() in src/base/intmath.hh. 
I think this implementation is not the best that can be done. We should 
use a GCC builtin __builtin_clz* to implement these functions. I have not 
carried out any test to get the execution times for two different 
implementations. But I looked at the assembly code generated for the two 
implementations for 64-bit version of the function. The ratio of number of 
instructions is probably about 1:4 for builtin versus current 
implementation.

Thanks
Nilay
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