[DFAJumpThreading] Add an early exit heuristic for unpredictable values (#85015)

Right now the algorithm does not exit on unpredictable values. It
waits until all the paths have been enumerated to see if any of
those paths have that value. Waiting this late leads to a lot of
wasteful computation and higher compile time.

In this patch I have added a heuristic that checks if the value
comes from the same inner loops as the switch, if so, then it is
likely that the value will also be seen on a threadable path and
the code in `getStateDefMap()` return an empty map.

I tested this on the llvm test suite and the only change in the
number of threaded switches was in 7zip (before 23, after 18).
In all of those cases the current algorithm was partially threading
the loop because it was hitting a limit on the number of paths to
be explored. On increasing this limit even the current algorithm
finds paths where the unpredictable value is seen.

Compile time(with pass enabled by default and this patch):

https://llvm-compile-time-tracker.com/compare.php?from=8c5e9cf737138aba22a4a8f64ef2c5efc80dd7f9&to=42c75d888058b35c6d15901b34e36251d8f766b9&stat=instructions:u

0 files changed, 0 insertions, 0 deletions