diff --git a/llvm/include/llvm/CodeGen/MachineOperand.h b/llvm/include/llvm/CodeGen/MachineOperand.h
--- a/llvm/include/llvm/CodeGen/MachineOperand.h
+++ b/llvm/include/llvm/CodeGen/MachineOperand.h
@@ -641,10 +641,6 @@
     return Contents.RegMask;
   }
 
-  /// Return the size of regmask array if we are able to figure it out from
-  /// this operand. Return zero otherwise.
-  unsigned getRegMaskSize() const;
-
   /// Returns number of elements needed for a regmask array.
   static unsigned getRegMaskSize(unsigned NumRegs) {
     return (NumRegs + 31) / 32;
diff --git a/llvm/lib/CodeGen/MachineOperand.cpp b/llvm/lib/CodeGen/MachineOperand.cpp
--- a/llvm/lib/CodeGen/MachineOperand.cpp
+++ b/llvm/lib/CodeGen/MachineOperand.cpp
@@ -18,6 +18,7 @@
 #include "llvm/CodeGen/MachineFrameInfo.h"
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/StableHashing.h"
 #include "llvm/CodeGen/TargetInstrInfo.h"
 #include "llvm/CodeGen/TargetRegisterInfo.h"
 #include "llvm/Config/llvm-config.h"
@@ -45,6 +46,7 @@
         return MF;
   return nullptr;
 }
+
 static MachineFunction *getMFIfAvailable(MachineOperand &MO) {
   return const_cast<MachineFunction *>(
       getMFIfAvailable(const_cast<const MachineOperand &>(MO)));
@@ -279,17 +281,6 @@
     RegInfo->addRegOperandToUseList(this);
 }
 
-/// getRegMaskSize - Return the size of regmask array if we are able to figure
-/// it out from this operand. Return zero otherwise.
-unsigned MachineOperand::getRegMaskSize() const {
-  if (const MachineFunction *MF = getMFIfAvailable(*this)) {
-    const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
-    unsigned RegMaskSize = (TRI->getNumRegs() + 31) / 32;
-    return RegMaskSize;
-  }
-  return 0;
-}
-
 /// isIdenticalTo - Return true if this operand is identical to the specified
 /// operand. Note that this should stay in sync with the hash_value overload
 /// below.
@@ -333,8 +324,9 @@
     if (RegMask == OtherRegMask)
       return true;
 
-    const unsigned RegMaskSize = getRegMaskSize();
-    if (RegMaskSize != 0) {
+    if (const MachineFunction *MF = getMFIfAvailable(*this)) {
+      const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
+      unsigned RegMaskSize = MachineOperand::getRegMaskSize(TRI->getNumRegs());
       // Deep compare of the two RegMasks
       return std::equal(RegMask, RegMask + RegMaskSize, OtherRegMask);
     }
@@ -390,8 +382,20 @@
     return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getBlockAddress(),
                         MO.getOffset());
   case MachineOperand::MO_RegisterMask:
-  case MachineOperand::MO_RegisterLiveOut:
-    return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getRegMask());
+  case MachineOperand::MO_RegisterLiveOut: {
+    if (const MachineFunction *MF = getMFIfAvailable(MO)) {
+      const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
+      unsigned RegMaskSize = MachineOperand::getRegMaskSize(TRI->getNumRegs());
+      const uint32_t *RegMask = MO.getRegMask();
+      std::vector<stable_hash> RegMaskHashes(RegMask, RegMask + RegMaskSize);
+      return hash_combine(MO.getType(), MO.getTargetFlags(),
+                          stable_hash_combine_array(RegMaskHashes.data(),
+                                                    RegMaskHashes.size()));
+    }
+
+    assert(0 && "MachineOperand not associated with any MachineFunction");
+    return hash_combine(MO.getType(), MO.getTargetFlags());
+  }
   case MachineOperand::MO_Metadata:
     return hash_combine(MO.getType(), MO.getTargetFlags(), MO.getMetadata());
   case MachineOperand::MO_MCSymbol:
diff --git a/llvm/lib/CodeGen/MachineStableHash.cpp b/llvm/lib/CodeGen/MachineStableHash.cpp
--- a/llvm/lib/CodeGen/MachineStableHash.cpp
+++ b/llvm/lib/CodeGen/MachineStableHash.cpp
@@ -120,17 +120,23 @@
 
   case MachineOperand::MO_RegisterMask:
   case MachineOperand::MO_RegisterLiveOut: {
-    const uint32_t *RegMask = MO.getRegMask();
-    const unsigned RegMaskSize = MO.getRegMaskSize();
-
-    if (RegMaskSize != 0) {
-      std::vector<llvm::stable_hash> RegMaskHashes(RegMask,
-                                                   RegMask + RegMaskSize);
-      return hash_combine(MO.getType(), MO.getTargetFlags(),
-                          stable_hash_combine_array(RegMaskHashes.data(),
-                                                    RegMaskHashes.size()));
+    if (const MachineInstr *MI = MO.getParent()) {
+      if (const MachineBasicBlock *MBB = MI->getParent()) {
+        if (const MachineFunction *MF = MBB->getParent()) {
+          const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
+          unsigned RegMaskSize =
+              MachineOperand::getRegMaskSize(TRI->getNumRegs());
+          const uint32_t *RegMask = MO.getRegMask();
+          std::vector<llvm::stable_hash> RegMaskHashes(RegMask,
+                                                       RegMask + RegMaskSize);
+          return hash_combine(MO.getType(), MO.getTargetFlags(),
+                              stable_hash_combine_array(RegMaskHashes.data(),
+                                                        RegMaskHashes.size()));
+        }
+      }
     }
 
+    assert(0 && "MachineOperand not associated with any MachineFunction");
     return hash_combine(MO.getType(), MO.getTargetFlags());
   }