[llvm] Match the inverse of m_AddOverflow (PR #147215)

[Nikita Popov via llvm-commits]

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@@ -2595,6 +2595,70 @@ struct UAddWithOverflow_match {
   }
 };
 
+//===----------------------------------------------------------------------===//
+// Matchers for overflow check patterns: e.g. (a + b) u< a, (a ^ -1) <u b
+// Note that S might be matched to other instructions than AddInst.
+//
+
+template <typename LHS_t, typename RHS_t, typename Sum_t>
+struct UAddWithOverflowInv_match {
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nikic wrote:

Can we handle this by adding an Invert template parameter to UAddWithOverflow which just inverts the Pred at the start and otherwise shares the code?

https://github.com/llvm/llvm-project/pull/147215