Make likelyhood of branches/conditions available throughout the compiler.
For simple code such as
if a > 10 then foo else bar it can make a big difference if we jump on
a > 10 or
a <= 10.
We already tracked the likelyhood of such conditionals for stack/heap checks in Cmm. I recently updated the native codegen on X86 to take this information into account where available and in one edge case this improved execution time from 1.7s to 1.5s!
Having this info available for other cases like bound checking (assume valid) or partial pattern matches (assume no match failure) should be a small win for most programs and hopefully a big one for a few of them.