[llvm] [ValueTracking] Add rotate idiom to haveNoCommonBitsSet special cases (PR #122165)

[via llvm-commits]

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@@ -229,6 +229,19 @@ static bool haveNoCommonBitsSetSpecialCases(const Value *LHS, const Value *RHS,
       return true;
   }
 
+  // Look for: (X << V) op (Y >> (BitWidth - V))
+  // or        (X >> V) op (Y << (BitWidth - V))
+  {
+    const Value *V;
+    const APInt *R;
+    if (((match(RHS, m_Shl(m_Value(), m_Sub(m_APInt(R), m_Value(V)))) &&
+          match(LHS, m_LShr(m_Value(), m_Specific(V)))) ||
+         (match(RHS, m_LShr(m_Value(), m_Sub(m_APInt(R), m_Value(V)))) &&
+          match(LHS, m_Shl(m_Value(), m_Specific(V))))) &&
+        R->uge(LHS->getType()->getScalarType()->getIntegerBitWidth()))
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goldsteinn wrote:

Think you are missing check that the `shl` and `lshr` are operating on the same `X`. I.e `m_Value(X)` in the `m_Shl` matchers and `m_Specific(X)` in the `m_LShr` matchers.

https://github.com/llvm/llvm-project/pull/122165