[llvm] [InstCombine] isKnownNonNegative should recognize `b - a` after `a <= b` (PR #145105)

[Yingwei Zheng via llvm-commits]

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+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
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dtcxzyw wrote:

Can you add some negative tests?


https://github.com/llvm/llvm-project/pull/145105