[SDPatternMatch] Add Matcher m_Undef

Author: AmrDeveloper

llvm/include/llvm/CodeGen/SDPatternMatch.h

@@ -138,6 +138,8 @@ struct Opcode_match {
 
 inline Opcode_match m_Opc(unsigned Opcode) { return Opcode_match(Opcode); }
 
+inline Opcode_match m_Undef() { return Opcode_match(ISD::UNDEF); }
+
 template <unsigned NumUses, typename Pattern> struct NUses_match {
   Pattern P;
 

llvm/unittests/CodeGen/SelectionDAGPatternMatchTest.cpp

@@ -603,3 +603,18 @@ TEST_F(SelectionDAGPatternMatchTest, matchAdvancedProperties) {
   EXPECT_TRUE(sd_match(Add, DAG.get(),
                        m_LegalOp(m_IntegerVT(m_Add(m_Value(), m_Value())))));
 }
+
+TEST_F(SelectionDAGPatternMatchTest, matchUndefined) {
+  auto BoolVT = EVT::getIntegerVT(Context, 1);
+  auto Int32VT = EVT::getIntegerVT(Context, 32);
+  auto VInt32VT = EVT::getVectorVT(Context, Int32VT, 4);
+
+  SDValue UndefBoolVT = DAG->getUNDEF(BoolVT);
+  SDValue UndefInt32VT= DAG->getUNDEF(Int32VT);
+  SDValue UndefVInt32VT = DAG->getUNDEF(VInt32VT);
+
+  using namespace SDPatternMatch;
+  EXPECT_TRUE(sd_match(UndefBoolVT, m_Undef()));
+  EXPECT_TRUE(sd_match(UndefInt32VT, m_Undef()));
+  EXPECT_TRUE(sd_match(UndefVInt32VT, m_Undef()));
+}