Profiling FIRRTL

The best way I've found to profile FIRRTL is by using FlameGraphs! The following is what works for me on an MacOSX Laptop.

Required installation:

• https://github.com/brendangregg/FlameGraph
• https://github.com/cykl/hprof2flamegraph

Then run:

> ./utils/bin/firrtl-profiling -i <testcase>.fir -o dump.v //Creates output.hprof
> stackcollapse-hprof output.hprof > output-folded.txt
> flamegraph.pl output-folded.txt > output.svg

You can then use your browser (e.g. Chrome) to view output.svg

You get pretty graphs like this: