+//===----------------------------------------------------------------------===//
+// Matchers for overflow check patterns: e.g. (a + b) u< a
+//
+
+template <typename LHS_t, typename RHS_t, typename Sum_t>
+struct UAddWithOverflow_match {
+ LHS_t L;
+ RHS_t R;
+ Sum_t S;
+
+ UAddWithOverflow_match(const LHS_t &L, const RHS_t &R, const Sum_t &S)
+ : L(L), R(R), S(S) {}
+
+ template <typename OpTy> bool match(OpTy *V) {
+ Value *ICmpLHS, *ICmpRHS;
+ ICmpInst::Predicate Pred;
+ if (!m_ICmp(Pred, m_Value(ICmpLHS), m_Value(ICmpRHS)).match(V))
+ return false;
+
+ Value *AddLHS, *AddRHS;
+ auto AddExpr = m_Add(m_Value(AddLHS), m_Value(AddRHS));
+
+ // (a + b) u< a, (a + b) u< b
+ if (Pred == ICmpInst::ICMP_ULT)
+ if (AddExpr.match(ICmpLHS) && (ICmpRHS == AddLHS || ICmpRHS == AddRHS))
+ return L.match(AddLHS) && R.match(AddRHS) && S.match(ICmpLHS);
+
+ // a >u (a + b), b >u (a + b)
+ if (Pred == ICmpInst::ICMP_UGT)
+ if (AddExpr.match(ICmpRHS) && (ICmpLHS == AddLHS || ICmpLHS == AddRHS))
+ return L.match(AddLHS) && R.match(AddRHS) && S.match(ICmpRHS);
+
+ return false;
+ }
+};
+
+/// \brief Match an icmp instruction checking for unsigned overflow on addition.
+///
+/// S is matched to the addition whose result is being checked for overflow, and
+/// L and R are matched to the LHS and RHS of S.
+template <typename LHS_t, typename RHS_t, typename Sum_t>
+UAddWithOverflow_match<LHS_t, RHS_t, Sum_t>
+m_UAddWithOverflow(const LHS_t &L, const RHS_t &R, const Sum_t &S) {
+ return UAddWithOverflow_match<LHS_t, RHS_t, Sum_t>(L, R, S);
+}
+