[PatternMatch] Add m_AddLike matcher (NFC)

This matches either a plain "add" or an "or disjoint" that can
be converted into an add. The AddLike terminology is adopted from
the SDAG layer.

Author: nikic

llvm/include/llvm/IR/PatternMatch.h

@@ -1270,6 +1270,14 @@ inline DisjointOr_match<LHS, RHS, true> m_c_DisjointOr(const LHS &L,
   return DisjointOr_match<LHS, RHS, true>(L, R);
 }
 
+/// Match either "and" or "or disjoint".
+template <typename LHS, typename RHS>
+inline match_combine_or<BinaryOp_match<LHS, RHS, Instruction::Add>,
+                        DisjointOr_match<LHS, RHS>>
+m_AddLike(const LHS &L, const RHS &R) {
+  return m_CombineOr(m_Add(L, R), m_DisjointOr(L, R));
+}
+
 //===----------------------------------------------------------------------===//
 // Class that matches a group of binary opcodes.
 //

llvm/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp

@@ -300,8 +300,7 @@ Instruction *InstCombinerImpl::visitMul(BinaryOperator &I) {
     // Canonicalize (X|C1)*MulC -> X*MulC+C1*MulC.
     Value *X;
     Constant *C1;
-    if (match(Op0, m_OneUse(m_Add(m_Value(X), m_ImmConstant(C1)))) ||
-        match(Op0, m_OneUse(m_DisjointOr(m_Value(X), m_ImmConstant(C1))))) {
+    if (match(Op0, m_OneUse(m_AddLike(m_Value(X), m_ImmConstant(C1))))) {
       // C1*MulC simplifies to a tidier constant.
       Value *NewC = Builder.CreateMul(C1, MulC);
       auto *BOp0 = cast<BinaryOperator>(Op0);