DA uses `DependenceInfo::isKnownPredicate` instead of
`ScalarEvolution::isKnownPredicate` in several places. The former is
intended to be a "wrapper" for the later. Specifically, it performs the
following processes:
- Replace `zext(X) cmp zext(Y)` with `X cmp Y`.
- Replace `X >=s Y` with `X - Y >=s 0`
- Replace `X <=s Y` with `X - Y <=s 0`
- Replace `X >s Y` with `X - Y >s 0`
- Replace `X <s Y` with `X - Y <s 0`
The first one can return an incorrect result when the most significant
bit of `X` and `Y` are different. Everything other than the first one
can be incorrect when `X - Y` overflows. Actually, when a `SCEVUnknown`
is involved (e.g., `%n <s %n + 1` will be `0 <s 1`), this function often
returns a result that ignore the possibility of overflow.
This patch removes `DependenceInfo::isKnownPredicate` and replace all
uses of it with `ScalarEvolution::isKnownPredicate`. There is a
degradation in some test cases, but this should be correct.
Resolve#169810
6934c36a86