diff --git a/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp b/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp
index f0527611..9ab5a80 100644
--- a/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp
+++ b/llvm/unittests/CodeGen/GlobalISel/LegalizerHelperTest.cpp
@@ -11,6 +11,13 @@
 
 namespace {
 
+class DummyGISelObserver : public GISelChangeObserver {
+public:
+  void changedInstr(MachineInstr &MI) override {}
+  void createdInstr(MachineInstr &MI) override {}
+  void erasedInstr(MachineInstr &MI) override {}
+};
+
 // Test CTTZ expansion when CTTZ_ZERO_UNDEF is legal or custom,
 // in which case it becomes CTTZ_ZERO_UNDEF with select.
 TEST_F(LegalizerHelperTest, LowerBitCountingCTTZ0) {
@@ -23,7 +30,8 @@
   // Build Instr
   auto MIBCTTZ = B.buildInstr(TargetOpcode::G_CTTZ, LLT::scalar(64), Copies[0]);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   // Perform Legalization
   ASSERT_TRUE(Helper.lower(*MIBCTTZ, 0, LLT::scalar(64)) ==
               LegalizerHelper::LegalizeResult::Legalized);
@@ -51,7 +59,8 @@
   // Build Instr
   auto MIBCTTZ = B.buildInstr(TargetOpcode::G_CTTZ, LLT::scalar(64), Copies[0]);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   // Perform Legalization
   ASSERT_TRUE(Helper.lower(*MIBCTTZ, 0, LLT::scalar(64)) ==
               LegalizerHelper::LegalizeResult::Legalized);
@@ -81,7 +90,8 @@
   // Build
   auto MIBCTTZ = B.buildInstr(TargetOpcode::G_CTTZ, LLT::scalar(64), Copies[0]);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.lower(*MIBCTTZ, 0, LLT::scalar(64)) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -109,7 +119,8 @@
   auto MIBCTTZ =
       B.buildInstr(TargetOpcode::G_CTTZ_ZERO_UNDEF, LLT::scalar(64), Copies[0]);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.lower(*MIBCTTZ, 0, LLT::scalar(64)) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -132,7 +143,8 @@
   // Build
   auto MIBCTLZ = B.buildInstr(TargetOpcode::G_CTLZ, LLT::scalar(64), Copies[0]);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.lower(*MIBCTLZ, 0, LLT::scalar(64)) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -159,7 +171,8 @@
   // Build
   auto MIBCTLZ = B.buildInstr(TargetOpcode::G_CTLZ, LLT::scalar(64), Copies[0]);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.lower(*MIBCTLZ, 0, LLT::scalar(64)) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -189,7 +202,8 @@
   auto MIBTrunc = B.buildTrunc(s8, Copies[0]);
   auto MIBCTLZ = B.buildInstr(TargetOpcode::G_CTLZ, s8, MIBTrunc);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.lower(*MIBCTLZ, 0, s8) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -228,7 +242,8 @@
   auto MIBTrunc = B.buildTrunc(s8, Copies[0]);
   auto MIBCTLZ = B.buildInstr(TargetOpcode::G_CTLZ, s8, MIBTrunc);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.widenScalar(*MIBCTLZ, 0, s16) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -260,7 +275,8 @@
   auto MIBTrunc = B.buildTrunc(s8, Copies[0]);
   auto MIBCTLZ_ZU = B.buildInstr(TargetOpcode::G_CTLZ_ZERO_UNDEF, s8, MIBTrunc);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.widenScalar(*MIBCTLZ_ZU, 0, s16) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -292,7 +308,8 @@
   auto MIBTrunc = B.buildTrunc(s8, Copies[0]);
   auto MIBCTPOP = B.buildInstr(TargetOpcode::G_CTPOP, s8, MIBTrunc);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.widenScalar(*MIBCTPOP, 0, s16) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -323,7 +340,8 @@
   auto MIBCTTZ_ZERO_UNDEF =
       B.buildInstr(TargetOpcode::G_CTTZ_ZERO_UNDEF, s8, MIBTrunc);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.widenScalar(*MIBCTTZ_ZERO_UNDEF, 0, s16) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -353,7 +371,8 @@
   auto MIBTrunc = B.buildTrunc(s8, Copies[0]);
   auto MIBCTTZ = B.buildInstr(TargetOpcode::G_CTTZ, s8, MIBTrunc);
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.widenScalar(*MIBCTTZ, 0, s16) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -388,7 +407,8 @@
                       .addUse(MIBTrunc->getOperand(0).getReg())
                       .addUse(MIBTrunc->getOperand(0).getReg());
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.widenScalar(*MIBUAddO, 0, s16) ==
               LegalizerHelper::LegalizeResult::Legalized);
 
@@ -426,7 +446,8 @@
                       .addUse(MIBTrunc->getOperand(0).getReg())
                       .addUse(MIBTrunc->getOperand(0).getReg());
   AInfo Info(MF->getSubtarget());
-  LegalizerHelper Helper(*MF, Info);
+  DummyGISelObserver Observer;
+  LegalizerHelper Helper(*MF, Info, Observer);
   ASSERT_TRUE(Helper.widenScalar(*MIBUSUBO, 0, s16) ==
               LegalizerHelper::LegalizeResult::Legalized);