Comment 5 for bug 851258

I should also mention that where the compiler is currently taking common comparison results and storing them in whole registers, it could potentially use the technique above to merge all of these -- its own temporary booleans -- into that same packed booleans register at the cost of one conditional bit-setting operation at comparison time. That's probably kind of obvious, but I thought maybe worth logging anyway.

Is there any simple way to estimate how many booleans the compiler might be keeping in flight at a time to see where this could save registers?