[DAGCombine] optimizeSetCCOfSignedTruncationCheck(): handle inverted pattern

Summary:
A follow-up for D49266 / rL337166 + D49497 / rL338044.

This is still the same pattern to check for the [lack of]
signed truncation, but in this case the constants and the predicate
are negated.

https://rise4fun.com/Alive/BDV
https://rise4fun.com/Alive/n7Z

Reviewers: spatel, craig.topper, RKSimon, javed.absar, efriedma, dmgreen

Reviewed By: spatel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D51532

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@341287 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed