[SCEV] Use context sensitive reasoning in howFarToZero (#94525)

This change builds on 0a357ad which supported non-constant strides in
howFarToZero, but used only context insensitive reasoning.

This change does two things:
1) Directly use context sensitive queries to prove facts established
   before the loop.  Note that we technically only need facts known
   at the latch, but using facts known on entry is a conservative
   approximation which will cover most everything.
2) For the non-zero check, we can usually prove non-zero from the
   finite assumption implied by mustprogress.  This eliminates the
   need to do the context sensitive query in the common case.

0 files changed, 0 insertions, 0 deletions