[clang] [ValueTracking] Simplify uaddo pattern (PR #65910)

[Yingwei Zheng via cfe-commits]

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@@ -8291,6 +8291,29 @@ static std::optional<bool> isImpliedCondICmps(const ICmpInst *LHS,
   if (L0 == R0 && match(L1, m_APInt(LC)) && match(R1, m_APInt(RC)))
     return isImpliedCondCommonOperandWithConstants(LPred, *LC, RPred, *RC);
 
+  // L0 = R0 = L1 + R1, L0 >=u L1 implies R0 >=u R1, L0 <u L1 implies R0 <u R1
+  if (ICmpInst::isUnsigned(LPred) && ICmpInst::isUnsigned(RPred)) {
+    if (L0 == R1) {
+      std::swap(R0, R1);
+      RPred = ICmpInst::getSwappedPredicate(RPred);
+    }
+    if (L1 == R0) {
+      std::swap(L0, L1);
+      LPred = ICmpInst::getSwappedPredicate(LPred);
+    }
+    if (L1 == R1) {
+      std::swap(L0, L1);
+      LPred = ICmpInst::getSwappedPredicate(LPred);
+      std::swap(R0, R1);
+      RPred = ICmpInst::getSwappedPredicate(RPred);
+    }
+    if (L0 == R0 &&
+        (LPred == ICmpInst::ICMP_UGE || LPred == ICmpInst::ICMP_ULT) &&
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dtcxzyw wrote:

It is not true for `L0 >u L1 -> R0 >u R1` and  `L0 <=u L1 -> R0 <=u R1`.
Alive2: https://alive2.llvm.org/ce/z/VKtFkD

https://github.com/llvm/llvm-project/pull/65910