[llvm] [DA] Check monotonicity for subscripts (PR #154527)

[Ryotaro Kasuga via llvm-commits]

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@@ -3308,6 +3308,322 @@ void DependenceInfo::updateDirection(Dependence::DVEntry &Level,
     llvm_unreachable("constraint has unexpected kind");
 }
 
+namespace {
+
+enum class MonotonicityType {
+  MaySignedWrap, ///< The expression contains arithmetic operations that may
+                 ///< cause signed wrap.
+  Constant,      ///< The expression is constant. If a SCEV is classified as
+                 ///< Constant, it also implies that it doesn't contain any
+                 ///< arithmetic operations that may cause signed wrap.
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kasuga-fj wrote:

Yes, "invariant" seems more reasonable here.

https://github.com/llvm/llvm-project/pull/154527