GlobalISel: Add matcher for G_LSHR

Author: arsenm

llvm/include/llvm/CodeGen/GlobalISel/MIPatternMatch.h

@@ -241,6 +241,12 @@ inline BinaryOp_match<LHS, RHS, TargetOpcode::G_OR, true> m_GOr(const LHS &L,
   return BinaryOp_match<LHS, RHS, TargetOpcode::G_OR, true>(L, R);
 }
 
+template <typename LHS, typename RHS>
+inline BinaryOp_match<LHS, RHS, TargetOpcode::G_LSHR, false>
+m_GLShr(const LHS &L, const RHS &R) {
+  return BinaryOp_match<LHS, RHS, TargetOpcode::G_LSHR, false>(L, R);
+}
+
 // Helper for unary instructions (G_[ZSA]EXT/G_TRUNC) etc
 template <typename SrcTy, unsigned Opcode> struct UnaryOp_match {
   SrcTy L;

llvm/unittests/CodeGen/GlobalISel/PatternMatchTest.cpp

@@ -45,6 +45,7 @@ TEST_F(GISelMITest, MatchBinaryOp) {
   setUp();
   if (!TM)
     return;
+  LLT s32 = LLT::scalar(32);
   LLT s64 = LLT::scalar(64);
   auto MIBAdd = B.buildAdd(s64, Copies[0], Copies[1]);
   // Test case for no bind.
@@ -127,6 +128,15 @@ TEST_F(GISelMITest, MatchBinaryOp) {
   EXPECT_TRUE(match);
   EXPECT_EQ(Src0, Copies[0]);
   EXPECT_EQ(Src1, Copies[1]);
+
+  // Match lshr, and make sure a different shift amount type works.
+  auto TruncCopy1 = B.buildTrunc(s32, Copies[1]);
+  auto LShr = B.buildLShr(s64, Copies[0], TruncCopy1);
+  match = mi_match(LShr.getReg(0), *MRI,
+                   m_GLShr(m_Reg(Src0), m_Reg(Src1)));
+  EXPECT_TRUE(match);
+  EXPECT_EQ(Src0, Copies[0]);
+  EXPECT_EQ(Src1, TruncCopy1.getReg(0));
 }
 
 TEST_F(GISelMITest, MatchICmp) {