diff --git a/include/avian/codegen/assembler.h b/include/avian/codegen/assembler.h
index 4331c11465..25707f4853 100644
--- a/include/avian/codegen/assembler.h
+++ b/include/avian/codegen/assembler.h
@@ -26,11 +26,11 @@ class Architecture;
 class OperandInfo {
  public:
   const unsigned size;
-  const lir::OperandType type;
+  const lir::Operand::Type type;
   lir::Operand* const operand;
 
   inline OperandInfo(unsigned size,
-                     lir::OperandType type,
+                     lir::Operand::Type type,
                      lir::Operand* operand)
       : size(size), type(type), operand(operand)
   {
diff --git a/include/avian/codegen/lir.h b/include/avian/codegen/lir.h
index 251e31aadd..91b48fb96d 100644
--- a/include/avian/codegen/lir.h
+++ b/include/avian/codegen/lir.h
@@ -79,17 +79,8 @@ const unsigned NonBranchTernaryOperationCount = FloatMin + 1;
 const unsigned BranchOperationCount = JumpIfFloatGreaterOrEqualOrUnordered
                                       - FloatMin;
 
-enum OperandType {
-  ConstantOperand,
-  AddressOperand,
-  RegisterOperand,
-  MemoryOperand
-};
-
 enum ValueType { ValueGeneral, ValueFloat };
 
-const unsigned OperandTypeCount = MemoryOperand + 1;
-
 const int NoRegister = -1;
 
 inline bool isBranch(lir::TernaryOperation op)
@@ -128,6 +119,16 @@ inline bool isFloatUnaryOp(lir::BinaryOperation op)
 }
 
 class Operand {
+public:
+
+  enum class Type {
+    Constant,
+    Address,
+    RegisterPair,
+    Memory
+  };
+
+  const static unsigned TypeCount = (unsigned)Type::Memory + 1;
 };
 
 class Constant : public Operand {
diff --git a/src/codegen/compiler.cpp b/src/codegen/compiler.cpp
index 32047d52fc..1e367497d5 100644
--- a/src/codegen/compiler.cpp
+++ b/src/codegen/compiler.cpp
@@ -256,7 +256,7 @@ Site* pickTargetSite(Context* c,
 
   expect(c, target.cost < Target::Impossible);
 
-  if (target.type == lir::MemoryOperand) {
+  if (target.type == lir::Operand::Type::Memory) {
     return frameSite(c, target.index);
   } else {
     return registerSite(c, target.index);
@@ -369,7 +369,7 @@ Site* maybeMove(Context* c,
       size,
       src,
       tmp,
-      OperandMask(1 << dstSite->type(c), dstSite->registerMask(c), 0));
+      OperandMask(1 << (unsigned)dstSite->type(c), dstSite->registerMask(c), 0));
 
   SiteMask srcMask = SiteMask::lowPart(src);
   unsigned cost = 0xFFFFFFFF;
@@ -514,14 +514,14 @@ void steal(Context* c, Resource* r, Value* thief)
 
 SiteMask generalRegisterMask(Context* c)
 {
-  return SiteMask(1 << lir::RegisterOperand,
+  return SiteMask(1 << (unsigned)lir::Operand::Type::RegisterPair,
                   c->regFile->generalRegisters.mask,
                   NoFrameIndex);
 }
 
 SiteMask generalRegisterOrConstantMask(Context* c)
 {
-  return SiteMask((1 << lir::RegisterOperand) | (1 << lir::ConstantOperand),
+  return SiteMask((1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Constant),
                   c->regFile->generalRegisters.mask,
                   NoFrameIndex);
 }
@@ -616,11 +616,11 @@ bool isHome(Value* v, int frameIndex)
 bool acceptForResolve(Context* c, Site* s, Read* read, const SiteMask& mask)
 {
   if (acceptMatch(c, s, read, mask) and (not s->frozen(c))) {
-    if (s->type(c) == lir::RegisterOperand) {
+    if (s->type(c) == lir::Operand::Type::RegisterPair) {
       return c->availableGeneralRegisterCount > ResolveRegisterReserveCount;
     } else {
       assertT(c,
-              s->match(c, SiteMask(1 << lir::MemoryOperand, 0, AnyFrameIndex)));
+              s->match(c, SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, AnyFrameIndex)));
 
       return isHome(read->value,
                     offsetToFrameIndex(c, static_cast<MemorySite*>(s)->offset));
@@ -698,7 +698,7 @@ void apply(Context* c,
 {
   assertT(c, s1Low->type(c) == s1High->type(c));
 
-  lir::OperandType s1Type = s1Low->type(c);
+  lir::Operand::Type s1Type = s1Low->type(c);
   OperandUnion s1Union;
   asAssemblerOperand(c, s1Low, s1High, &s1Union);
 
@@ -717,11 +717,11 @@ void apply(Context* c,
   assertT(c, s1Low->type(c) == s1High->type(c));
   assertT(c, s2Low->type(c) == s2High->type(c));
 
-  lir::OperandType s1Type = s1Low->type(c);
+  lir::Operand::Type s1Type = s1Low->type(c);
   OperandUnion s1Union;
   asAssemblerOperand(c, s1Low, s1High, &s1Union);
 
-  lir::OperandType s2Type = s2Low->type(c);
+  lir::Operand::Type s2Type = s2Low->type(c);
   OperandUnion s2Union;
   asAssemblerOperand(c, s2Low, s2High, &s2Union);
 
@@ -746,15 +746,15 @@ void apply(Context* c,
   assertT(c, s2Low->type(c) == s2High->type(c));
   assertT(c, s3Low->type(c) == s3High->type(c));
 
-  lir::OperandType s1Type = s1Low->type(c);
+  lir::Operand::Type s1Type = s1Low->type(c);
   OperandUnion s1Union;
   asAssemblerOperand(c, s1Low, s1High, &s1Union);
 
-  lir::OperandType s2Type = s2Low->type(c);
+  lir::Operand::Type s2Type = s2Low->type(c);
   OperandUnion s2Union;
   asAssemblerOperand(c, s2Low, s2High, &s2Union);
 
-  lir::OperandType s3Type = s3Low->type(c);
+  lir::Operand::Type s3Type = s3Low->type(c);
   OperandUnion s3Union;
   asAssemblerOperand(c, s3Low, s3High, &s3Union);
 
@@ -782,7 +782,7 @@ void saveLocals(Context* c, Event* e)
       e->addRead(
           c,
           local->value,
-          SiteMask(1 << lir::MemoryOperand, 0, compiler::frameIndex(c, li)));
+          SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, compiler::frameIndex(c, li)));
     }
   }
 }
@@ -815,10 +815,10 @@ void maybeMove(Context* c,
 
   if (cost) {
     // todo: let c->arch->planMove decide this:
-    bool useTemporary = ((target->type(c) == lir::MemoryOperand
-                          and srcValue->source->type(c) == lir::MemoryOperand)
+    bool useTemporary = ((target->type(c) == lir::Operand::Type::Memory
+                          and srcValue->source->type(c) == lir::Operand::Type::Memory)
                          or (srcSelectSize < dstSize
-                             and target->type(c) != lir::RegisterOperand));
+                             and target->type(c) != lir::Operand::Type::RegisterPair));
 
     srcValue->source->freeze(c, srcValue);
 
@@ -827,7 +827,7 @@ void maybeMove(Context* c,
     srcValue->source->thaw(c, srcValue);
 
     bool addOffset = srcSize != srcSelectSize and c->arch->bigEndian()
-                     and srcValue->source->type(c) == lir::MemoryOperand;
+                     and srcValue->source->type(c) == lir::Operand::Type::Memory;
 
     if (addOffset) {
       static_cast<MemorySite*>(srcValue->source)->offset
@@ -878,7 +878,7 @@ void maybeMove(Context* c,
       }
 
       assertT(c, thunk == 0);
-      assertT(c, dstMask.typeMask & src.typeMask & (1 << lir::RegisterOperand));
+      assertT(c, dstMask.typeMask & src.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair));
 
       Site* tmpTarget
           = freeRegisterSite(c, dstMask.registerMask & src.lowRegisterMask);
@@ -1635,7 +1635,7 @@ bool resolveSourceSites(Context* c,
     Read* r = live(c, v);
 
     if (r and sites[el.localIndex] == 0) {
-      SiteMask mask((1 << lir::RegisterOperand) | (1 << lir::MemoryOperand),
+      SiteMask mask((1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Memory),
                     c->regFile->generalRegisters.mask,
                     AnyFrameIndex);
 
@@ -1677,7 +1677,7 @@ void resolveTargetSites(Context* c,
     Read* r = live(c, v);
 
     if (r and sites[el.localIndex] == 0) {
-      SiteMask mask((1 << lir::RegisterOperand) | (1 << lir::MemoryOperand),
+      SiteMask mask((1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Memory),
                     c->regFile->generalRegisters.mask,
                     AnyFrameIndex);
 
diff --git a/src/codegen/compiler/event.cpp b/src/codegen/compiler/event.cpp
index 789d470f44..d5b6a67dcf 100644
--- a/src/codegen/compiler/event.cpp
+++ b/src/codegen/compiler/event.cpp
@@ -415,7 +415,7 @@ class CallEvent : public Event {
             fprintf(stderr, "stack %d arg read %p\n", frameIndex, v);
           }
 
-          targetMask = SiteMask(1 << lir::MemoryOperand, 0, frameIndex);
+          targetMask = SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, frameIndex);
         }
 
         this->addRead(c, v, targetMask);
@@ -512,7 +512,7 @@ class CallEvent : public Event {
             this->addRead(c, v, generalRegisterMask(c));
           } else {
             this->addRead(
-                c, v, SiteMask(1 << lir::MemoryOperand, 0, frameIndex));
+                c, v, SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, frameIndex));
           }
         }
       }
@@ -544,7 +544,7 @@ class CallEvent : public Event {
 
           this->addRead(c,
                         stack->value,
-                        SiteMask(1 << lir::MemoryOperand, 0, logicalIndex));
+                        SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, logicalIndex));
         }
 
         stack = stack->next;
@@ -581,11 +581,11 @@ class CallEvent : public Event {
       assertT(
           c,
           returnAddressSurrogate == 0
-          or returnAddressSurrogate->source->type(c) == lir::RegisterOperand);
+          or returnAddressSurrogate->source->type(c) == lir::Operand::Type::RegisterPair);
       assertT(
           c,
           framePointerSurrogate == 0
-          or framePointerSurrogate->source->type(c) == lir::RegisterOperand);
+          or framePointerSurrogate->source->type(c) == lir::Operand::Type::RegisterPair);
 
       int ras;
       if (returnAddressSurrogate) {
@@ -783,7 +783,7 @@ class MoveEvent : public Event {
         op,
         srcSelectSize,
         OperandMask(
-            1 << srcValue->source->type(c),
+            1 << (unsigned)srcValue->source->type(c),
             srcValue->source->registerMask(c),
             srcValue->nextWord->source->registerMask(c)),
         dstSize,
@@ -866,7 +866,7 @@ class MoveEvent : public Event {
       assertT(c, srcSelectSize == c->targetInfo.pointerSize);
 
       if (dstValue->nextWord->target or live(c, dstValue->nextWord)) {
-        assertT(c, dstLowMask.typeMask & (1 << lir::RegisterOperand));
+        assertT(c, dstLowMask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair));
 
         Site* low = freeRegisterSite(c, dstLowMask.registerMask);
 
@@ -897,7 +897,7 @@ class MoveEvent : public Event {
 
         srcValue->source->thaw(c, srcValue);
 
-        assertT(c, dstHighMask.typeMask & (1 << lir::RegisterOperand));
+        assertT(c, dstHighMask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair));
 
         Site* high = freeRegisterSite(c, dstHighMask.registerMask);
 
@@ -1126,12 +1126,12 @@ class CombineEvent : public Event {
         op,
         firstValue->type.size(c->targetInfo),
         OperandMask(
-            1 << firstValue->source->type(c),
+            1 << (unsigned)firstValue->source->type(c),
             firstValue->source->registerMask(c),
             firstValue->nextWord->source->registerMask(c)),
         secondValue->type.size(c->targetInfo),
         OperandMask(
-            1 << secondValue->source->type(c),
+            1 << (unsigned)secondValue->source->type(c),
             secondValue->source->registerMask(c),
             secondValue->nextWord->source->registerMask(c)),
         resultValue->type.size(c->targetInfo),
@@ -1314,7 +1314,7 @@ class TranslateEvent : public Event {
         op,
         firstValue->type.size(c->targetInfo),
         OperandMask(
-            1 << firstValue->source->type(c),
+            1 << (unsigned)firstValue->source->type(c),
             firstValue->source->registerMask(c),
             firstValue->nextWord->source->registerMask(c)),
         resultValue->type.size(c->targetInfo),
@@ -1451,7 +1451,7 @@ ConstantSite* findConstantSite(Context* c, Value* v)
 {
   for (SiteIterator it(c, v); it.hasMore();) {
     Site* s = it.next();
-    if (s->type(c) == lir::ConstantOperand) {
+    if (s->type(c) == lir::Operand::Type::Constant) {
       return static_cast<ConstantSite*>(s);
     }
   }
@@ -1461,7 +1461,7 @@ ConstantSite* findConstantSite(Context* c, Value* v)
 void moveIfConflict(Context* c, Value* v, MemorySite* s)
 {
   if (v->reads) {
-    SiteMask mask(1 << lir::RegisterOperand, ~0, AnyFrameIndex);
+    SiteMask mask(1 << (unsigned)lir::Operand::Type::RegisterPair, ~0, AnyFrameIndex);
     v->reads->intersect(&mask);
     if (s->conflicts(mask)) {
       maybeMove(c, v->reads, true, false);
@@ -1509,13 +1509,13 @@ class MemoryEvent : public Event {
         displacement += (constant->value->value() * scale);
         scale = 1;
       } else {
-        assertT(c, index->source->type(c) == lir::RegisterOperand);
+        assertT(c, index->source->type(c) == lir::Operand::Type::RegisterPair);
         indexRegister = static_cast<RegisterSite*>(index->source)->number;
       }
     } else {
       indexRegister = lir::NoRegister;
     }
-    assertT(c, base->source->type(c) == lir::RegisterOperand);
+    assertT(c, base->source->type(c) == lir::Operand::Type::RegisterPair);
     int baseRegister = static_cast<RegisterSite*>(base->source)->number;
 
     popRead(c, this, base);
@@ -1873,12 +1873,12 @@ void clean(Context* c, Value* v, unsigned popIndex)
 {
   for (SiteIterator it(c, v); it.hasMore();) {
     Site* s = it.next();
-    if (not(s->match(c, SiteMask(1 << lir::MemoryOperand, 0, AnyFrameIndex))
+    if (not(s->match(c, SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, AnyFrameIndex))
             and offsetToFrameIndex(c, static_cast<MemorySite*>(s)->offset)
                 >= popIndex)) {
       if (false
           and s->match(c,
-                       SiteMask(1 << lir::MemoryOperand, 0, AnyFrameIndex))) {
+                       SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, AnyFrameIndex))) {
         char buffer[256];
         s->toString(c, buffer, 256);
         fprintf(stderr,
@@ -2010,7 +2010,7 @@ class BoundsCheckEvent : public Event {
         lir::Constant handlerConstant(resolvedPromise(c, handler));
         a->apply(lir::Call,
                  OperandInfo(c->targetInfo.pointerSize,
-                             lir::ConstantOperand,
+                             lir::Operand::Type::Constant,
                              &handlerConstant));
       }
     } else {
@@ -2032,7 +2032,7 @@ class BoundsCheckEvent : public Event {
     }
 
     if (constant == 0 or constant->value->value() >= 0) {
-      assertT(c, object->source->type(c) == lir::RegisterOperand);
+      assertT(c, object->source->type(c) == lir::Operand::Type::RegisterPair);
       MemorySite length(static_cast<RegisterSite*>(object->source)->number,
                         lengthOffset,
                         lir::NoRegister,
@@ -2066,7 +2066,7 @@ class BoundsCheckEvent : public Event {
       lir::Constant handlerConstant(resolvedPromise(c, handler));
       a->apply(lir::Call,
                OperandInfo(c->targetInfo.pointerSize,
-                           lir::ConstantOperand,
+                           lir::Operand::Type::Constant,
                            &handlerConstant));
 
       nextPromise->offset = a->offset();
diff --git a/src/codegen/compiler/read.cpp b/src/codegen/compiler/read.cpp
index 0c7d09fd76..d9909ed343 100644
--- a/src/codegen/compiler/read.cpp
+++ b/src/codegen/compiler/read.cpp
@@ -205,7 +205,7 @@ Read* StubRead::next(Context*)
 SingleRead* read(Context* c, const SiteMask& mask, Value* successor)
 {
   assertT(c,
-          (mask.typeMask != 1 << lir::MemoryOperand) or mask.frameIndex >= 0);
+          (mask.typeMask != 1 << (unsigned)lir::Operand::Type::Memory) or mask.frameIndex >= 0);
 
   return new (c->zone) SingleRead(mask, successor);
 }
diff --git a/src/codegen/compiler/regalloc.cpp b/src/codegen/compiler/regalloc.cpp
index b75162405d..0c60ae0d0d 100644
--- a/src/codegen/compiler/regalloc.cpp
+++ b/src/codegen/compiler/regalloc.cpp
@@ -71,7 +71,7 @@ bool pickRegisterTarget(Context* c,
               c,
               v,
               r,
-              SiteMask(1 << lir::RegisterOperand, 1 << i, NoFrameIndex),
+              SiteMask(1 << (unsigned)lir::Operand::Type::RegisterPair, 1 << i, NoFrameIndex),
               costCalculator) + Target::MinimumRegisterCost;
 
     if (mask.containsExactly(i)) {
@@ -124,7 +124,7 @@ Target pickRegisterTarget(Context* c,
 {
   unsigned cost;
   Register number = pickRegisterTarget(c, v, mask, &cost, costCalculator);
-  return Target(number, lir::RegisterOperand, cost);
+  return Target(number, lir::Operand::Type::RegisterPair, cost);
 }
 
 unsigned frameCost(Context* c,
@@ -135,7 +135,7 @@ unsigned frameCost(Context* c,
   return resourceCost(c,
                       v,
                       c->frameResources + frameIndex,
-                      SiteMask(1 << lir::MemoryOperand, 0, frameIndex),
+                      SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, frameIndex),
                       costCalculator) + Target::MinimumFrameCost;
 }
 
@@ -147,7 +147,7 @@ Target pickFrameTarget(Context* c, Value* v, CostCalculator* costCalculator)
   do {
     if (p->home >= 0) {
       Target mine(p->home,
-                  lir::MemoryOperand,
+                  lir::Operand::Type::Memory,
                   frameCost(c, v, p->home, costCalculator));
 
       if (mine.cost == Target::MinimumFrameCost) {
@@ -168,7 +168,7 @@ Target pickAnyFrameTarget(Context* c, Value* v, CostCalculator* costCalculator)
 
   unsigned count = totalFrameSize(c);
   for (unsigned i = 0; i < count; ++i) {
-    Target mine(i, lir::MemoryOperand, frameCost(c, v, i, costCalculator));
+    Target mine(i, lir::Operand::Type::Memory, frameCost(c, v, i, costCalculator));
     if (mine.cost == Target::MinimumFrameCost) {
       return mine;
     } else if (mine.cost < best.cost) {
@@ -186,7 +186,7 @@ Target pickTarget(Context* c,
                   Target best,
                   CostCalculator* costCalculator)
 {
-  if (mask.typeMask & (1 << lir::RegisterOperand)) {
+  if (mask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair)) {
     Target mine
         = pickRegisterTarget(c, value, mask.registerMask, costCalculator);
 
@@ -198,10 +198,10 @@ Target pickTarget(Context* c,
     }
   }
 
-  if (mask.typeMask & (1 << lir::MemoryOperand)) {
+  if (mask.typeMask & (1 << (unsigned)lir::Operand::Type::Memory)) {
     if (mask.frameIndex >= 0) {
       Target mine(mask.frameIndex,
-                  lir::MemoryOperand,
+                  lir::Operand::Type::Memory,
                   frameCost(c, value, mask.frameIndex, costCalculator));
       if (mine.cost == Target::MinimumFrameCost) {
         return mine;
diff --git a/src/codegen/compiler/regalloc.h b/src/codegen/compiler/regalloc.h
index e512e63183..0dab9d1e3d 100644
--- a/src/codegen/compiler/regalloc.h
+++ b/src/codegen/compiler/regalloc.h
@@ -55,13 +55,13 @@ class Target {
   {
   }
 
-  Target(Register index, lir::OperandType type, unsigned cost)
+  Target(Register index, lir::Operand::Type type, unsigned cost)
       : index(index), type(type), cost(cost)
   {
   }
 
   int16_t index;
-  lir::OperandType type;
+  lir::Operand::Type type;
   uint8_t cost;
 };
 
diff --git a/src/codegen/compiler/site.cpp b/src/codegen/compiler/site.cpp
index 1f83991a4a..99ce5fb154 100644
--- a/src/codegen/compiler/site.cpp
+++ b/src/codegen/compiler/site.cpp
@@ -152,7 +152,7 @@ class AddressSite : public Site {
 
   virtual bool match(Context*, const SiteMask& mask)
   {
-    return mask.typeMask & (1 << lir::AddressOperand);
+    return mask.typeMask & (1 << (unsigned)lir::Operand::Type::Address);
   }
 
   virtual bool loneMatch(Context*, const SiteMask&)
@@ -165,9 +165,9 @@ class AddressSite : public Site {
     abort(c);
   }
 
-  virtual lir::OperandType type(Context*)
+  virtual lir::Operand::Type type(Context*)
   {
-    return lir::AddressOperand;
+    return lir::Operand::Type::Address;
   }
 
   virtual void asAssemblerOperand(Context* c UNUSED,
@@ -201,7 +201,7 @@ class AddressSite : public Site {
 
   virtual SiteMask mask(Context*)
   {
-    return SiteMask(1 << lir::AddressOperand, 0, NoFrameIndex);
+    return SiteMask(1 << (unsigned)lir::Operand::Type::Address, 0, NoFrameIndex);
   }
 
   virtual SiteMask nextWordMask(Context* c, unsigned)
@@ -237,7 +237,7 @@ unsigned RegisterSite::copyCost(Context* c, Site* s)
   assertT(c, number != lir::NoRegister);
 
   if (s and (this == s
-             or (s->type(c) == lir::RegisterOperand
+             or (s->type(c) == lir::Operand::Type::RegisterPair
                  and (static_cast<RegisterSite*>(s)->mask_.contains(number))))) {
     return 0;
   } else {
@@ -249,7 +249,7 @@ bool RegisterSite::match(Context* c UNUSED, const SiteMask& mask)
 {
   assertT(c, number != lir::NoRegister);
 
-  if ((mask.typeMask & (1 << lir::RegisterOperand))) {
+  if ((mask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair))) {
     return mask.registerMask.contains(number);
   } else {
     return false;
@@ -260,7 +260,7 @@ bool RegisterSite::loneMatch(Context* c UNUSED, const SiteMask& mask)
 {
   assertT(c, number != lir::NoRegister);
 
-  if ((mask.typeMask & (1 << lir::RegisterOperand))) {
+  if ((mask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair))) {
     return mask.registerMask.containsExactly(number);
   } else {
     return false;
@@ -271,7 +271,7 @@ bool RegisterSite::matchNextWord(Context* c, Site* s, unsigned)
 {
   assertT(c, number != lir::NoRegister);
 
-  if (s->type(c) != lir::RegisterOperand) {
+  if (s->type(c) != lir::Operand::Type::RegisterPair) {
     return false;
   }
 
@@ -290,7 +290,7 @@ void RegisterSite::acquire(Context* c, Value* v)
 {
   Target target;
   if (number != lir::NoRegister) {
-    target = Target(number, lir::RegisterOperand, 0);
+    target = Target(number, lir::Operand::Type::RegisterPair, 0);
   } else {
     target = pickRegisterTarget(c, v, mask_);
     expect(c, target.cost < Target::Impossible);
@@ -330,9 +330,9 @@ bool RegisterSite::frozen(Context* c UNUSED)
   return c->registerResources[number].freezeCount != 0;
 }
 
-lir::OperandType RegisterSite::type(Context*)
+lir::Operand::Type RegisterSite::type(Context*)
 {
-  return lir::RegisterOperand;
+  return lir::Operand::Type::RegisterPair;
 }
 
 void RegisterSite::asAssemblerOperand(Context* c UNUSED,
@@ -385,7 +385,7 @@ Site* RegisterSite::makeNextWord(Context* c, unsigned)
 
 SiteMask RegisterSite::mask(Context* c UNUSED)
 {
-  return SiteMask(1 << lir::RegisterOperand, mask_, NoFrameIndex);
+  return SiteMask(1 << (unsigned)lir::Operand::Type::RegisterPair, mask_, NoFrameIndex);
 }
 
 SiteMask RegisterSite::nextWordMask(Context* c, unsigned)
@@ -393,9 +393,9 @@ SiteMask RegisterSite::nextWordMask(Context* c, unsigned)
   assertT(c, number != lir::NoRegister);
 
   if (registerSize(c) > c->targetInfo.pointerSize) {
-    return SiteMask(1 << lir::RegisterOperand, number, NoFrameIndex);
+    return SiteMask(1 << (unsigned)lir::Operand::Type::RegisterPair, number, NoFrameIndex);
   } else {
-    return SiteMask(1 << lir::RegisterOperand,
+    return SiteMask(1 << (unsigned)lir::Operand::Type::RegisterPair,
                     c->regFile->generalRegisters.mask,
                     NoFrameIndex);
   }
@@ -453,7 +453,7 @@ unsigned MemorySite::copyCost(Context* c, Site* s)
 {
   assertT(c, acquired);
 
-  if (s and (this == s or (s->type(c) == lir::MemoryOperand
+  if (s and (this == s or (s->type(c) == lir::Operand::Type::Memory
                            and static_cast<MemorySite*>(s)->base == base
                            and static_cast<MemorySite*>(s)->offset == offset
                            and static_cast<MemorySite*>(s)->index == index
@@ -466,7 +466,7 @@ unsigned MemorySite::copyCost(Context* c, Site* s)
 
 bool MemorySite::conflicts(const SiteMask& mask)
 {
-  return (mask.typeMask & (1 << lir::RegisterOperand)) != 0
+  return (mask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair)) != 0
          and (!mask.registerMask.contains(base)
               or (index != lir::NoRegister
                   and !mask.registerMask.contains(index)));
@@ -476,7 +476,7 @@ bool MemorySite::match(Context* c, const SiteMask& mask)
 {
   assertT(c, acquired);
 
-  if (mask.typeMask & (1 << lir::MemoryOperand)) {
+  if (mask.typeMask & (1 << (unsigned)lir::Operand::Type::Memory)) {
     if (mask.frameIndex >= 0) {
       if (base == c->arch->stack()) {
         assertT(c, index == lir::NoRegister);
@@ -497,7 +497,7 @@ bool MemorySite::loneMatch(Context* c, const SiteMask& mask)
 {
   assertT(c, acquired);
 
-  if (mask.typeMask & (1 << lir::MemoryOperand)) {
+  if (mask.typeMask & (1 << (unsigned)lir::Operand::Type::Memory)) {
     if (base == c->arch->stack()) {
       assertT(c, index == lir::NoRegister);
 
@@ -513,7 +513,7 @@ bool MemorySite::loneMatch(Context* c, const SiteMask& mask)
 
 bool MemorySite::matchNextWord(Context* c, Site* s, unsigned index)
 {
-  if (s->type(c) == lir::MemoryOperand) {
+  if (s->type(c) == lir::Operand::Type::Memory) {
     MemorySite* ms = static_cast<MemorySite*>(s);
     return ms->base == this->base
            and ((index == 1
@@ -596,9 +596,9 @@ bool MemorySite::frozen(Context* c)
          and c->frameResources[offsetToFrameIndex(c, offset)].freezeCount != 0;
 }
 
-lir::OperandType MemorySite::type(Context*)
+lir::Operand::Type MemorySite::type(Context*)
 {
-  return lir::MemoryOperand;
+  return lir::Operand::Type::Memory;
 }
 
 void MemorySite::asAssemblerOperand(Context* c UNUSED,
@@ -657,7 +657,7 @@ Site* MemorySite::makeNextWord(Context* c, unsigned index)
 
 SiteMask MemorySite::mask(Context* c)
 {
-  return SiteMask(1 << lir::MemoryOperand,
+  return SiteMask(1 << (unsigned)lir::Operand::Type::Memory,
                   0,
                   (base == c->arch->stack())
                       ? static_cast<int>(offsetToFrameIndex(c, offset))
@@ -674,7 +674,7 @@ SiteMask MemorySite::nextWordMask(Context* c, unsigned index)
   } else {
     frameIndex = NoFrameIndex;
   }
-  return SiteMask(1 << lir::MemoryOperand, 0, frameIndex);
+  return SiteMask(1 << (unsigned)lir::Operand::Type::Memory, 0, frameIndex);
 }
 
 bool MemorySite::isVolatile(Context* c)
diff --git a/src/codegen/compiler/site.h b/src/codegen/compiler/site.h
index 6d549c116e..6344936e0c 100644
--- a/src/codegen/compiler/site.h
+++ b/src/codegen/compiler/site.h
@@ -43,7 +43,7 @@ class SiteMask {
 
   static SiteMask fixedRegisterMask(int number)
   {
-    return SiteMask(1 << lir::RegisterOperand, 1 << number, NoFrameIndex);
+    return SiteMask(1 << (unsigned)lir::Operand::Type::RegisterPair, 1 << number, NoFrameIndex);
   }
 
   static SiteMask lowPart(const OperandMask& mask)
@@ -103,7 +103,7 @@ class Site {
     return false;
   }
 
-  virtual lir::OperandType type(Context*) = 0;
+  virtual lir::Operand::Type type(Context*) = 0;
 
   virtual void asAssemblerOperand(Context*, Site*, lir::Operand*) = 0;
 
@@ -187,7 +187,7 @@ class ConstantSite : public Site {
 
   virtual bool match(Context*, const SiteMask& mask)
   {
-    return mask.typeMask & (1 << lir::ConstantOperand);
+    return mask.typeMask & (1 << (unsigned)lir::Operand::Type::Constant);
   }
 
   virtual bool loneMatch(Context*, const SiteMask&)
@@ -197,12 +197,12 @@ class ConstantSite : public Site {
 
   virtual bool matchNextWord(Context* c, Site* s, unsigned)
   {
-    return s->type(c) == lir::ConstantOperand;
+    return s->type(c) == lir::Operand::Type::Constant;
   }
 
-  virtual lir::OperandType type(Context*)
+  virtual lir::Operand::Type type(Context*)
   {
-    return lir::ConstantOperand;
+    return lir::Operand::Type::Constant;
   }
 
   virtual void asAssemblerOperand(Context* c, Site* high, lir::Operand* result)
@@ -236,12 +236,12 @@ class ConstantSite : public Site {
 
   virtual SiteMask mask(Context*)
   {
-    return SiteMask(1 << lir::ConstantOperand, 0, NoFrameIndex);
+    return SiteMask(1 << (unsigned)lir::Operand::Type::Constant, 0, NoFrameIndex);
   }
 
   virtual SiteMask nextWordMask(Context*, unsigned)
   {
-    return SiteMask(1 << lir::ConstantOperand, 0, NoFrameIndex);
+    return SiteMask(1 << (unsigned)lir::Operand::Type::Constant, 0, NoFrameIndex);
   }
 
   Promise* value;
@@ -273,7 +273,7 @@ class RegisterSite : public Site {
 
   virtual bool frozen(Context* c UNUSED);
 
-  virtual lir::OperandType type(Context*);
+  virtual lir::Operand::Type type(Context*);
 
   virtual void asAssemblerOperand(Context* c UNUSED,
                                   Site* high,
@@ -328,7 +328,7 @@ class MemorySite : public Site {
 
   virtual bool frozen(Context* c);
 
-  virtual lir::OperandType type(Context*);
+  virtual lir::Operand::Type type(Context*);
 
   virtual void asAssemblerOperand(Context* c UNUSED,
                                   Site* high UNUSED,
diff --git a/src/codegen/target/arm/assembler.cpp b/src/codegen/target/arm/assembler.cpp
index 84e7d8d3cc..c383aea819 100644
--- a/src/codegen/target/arm/assembler.cpp
+++ b/src/codegen/target/arm/assembler.cpp
@@ -396,7 +396,7 @@ class MyArchitecture : public Architecture {
                     OperandMask& aMask,
                     bool* thunk)
   {
-    aMask.typeMask = (1 << lir::RegisterOperand) | (1 << lir::ConstantOperand);
+    aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Constant);
     aMask.setLowHighRegisterMasks(~static_cast<uint64_t>(0), ~static_cast<uint64_t>(0));
     *thunk = false;
   }
@@ -413,7 +413,7 @@ class MyArchitecture : public Architecture {
 
     switch (op) {
     case lir::Negate:
-      aMask.typeMask = (1 << lir::RegisterOperand);
+      aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       aMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
       break;
 
@@ -426,7 +426,7 @@ class MyArchitecture : public Architecture {
     case lir::FloatNegate:
     case lir::Float2Float:
       if (vfpSupported()) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(FPR_MASK, FPR_MASK);
       } else {
         *thunk = true;
@@ -439,7 +439,7 @@ class MyArchitecture : public Architecture {
       // thunks or produce inline machine code which handles edge
       // cases properly.
       if (false && vfpSupported() && bSize == 4) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(FPR_MASK, FPR_MASK);
       } else {
         *thunk = true;
@@ -448,7 +448,7 @@ class MyArchitecture : public Architecture {
 
     case lir::Int2Float:
       if (vfpSupported() && aSize == 4) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
       } else {
         *thunk = true;
@@ -466,12 +466,12 @@ class MyArchitecture : public Architecture {
                                unsigned,
                                OperandMask& bMask)
   {
-    bMask.typeMask = (1 << lir::RegisterOperand) | (1 << lir::MemoryOperand);
+    bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Memory);
     bMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
 
     switch (op) {
     case lir::Negate:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       bMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
       break;
 
@@ -480,18 +480,18 @@ class MyArchitecture : public Architecture {
     case lir::FloatNegate:
     case lir::Float2Float:
     case lir::Int2Float:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       bMask.setLowHighRegisterMasks(FPR_MASK, FPR_MASK);
       break;
 
     case lir::Float2Int:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       bMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
       break;
 
     case lir::Move:
-      if (!(aMask.typeMask & 1 << lir::RegisterOperand)) {
-        bMask.typeMask = 1 << lir::RegisterOperand;
+      if (!(aMask.typeMask & 1 << (unsigned)lir::Operand::Type::RegisterPair)) {
+        bMask.typeMask = 1 << (unsigned)lir::Operand::Type::RegisterPair;
       }
       break;
 
@@ -511,15 +511,15 @@ class MyArchitecture : public Architecture {
     tmpMask.typeMask = 0;
     tmpMask.setLowHighRegisterMasks(0, 0);
 
-    if (dstMask.typeMask & (1 << lir::MemoryOperand)) {
+    if (dstMask.typeMask & (1 << (unsigned)lir::Operand::Type::Memory)) {
       // can't move directly from memory or constant to memory
-      srcMask.typeMask = 1 << lir::RegisterOperand;
-      tmpMask.typeMask = 1 << lir::RegisterOperand;
+      srcMask.typeMask = 1 << (unsigned)lir::Operand::Type::RegisterPair;
+      tmpMask.typeMask = 1 << (unsigned)lir::Operand::Type::RegisterPair;
       tmpMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
-    } else if (vfpSupported() && dstMask.typeMask & 1 << lir::RegisterOperand
+    } else if (vfpSupported() && dstMask.typeMask & 1 << (unsigned)lir::Operand::Type::RegisterPair
                && dstMask.lowRegisterMask & FPR_MASK) {
-      srcMask.typeMask = tmpMask.typeMask = 1 << lir::RegisterOperand
-                                            | 1 << lir::MemoryOperand;
+      srcMask.typeMask = tmpMask.typeMask = 1 << (unsigned)lir::Operand::Type::RegisterPair
+                                            | 1 << (unsigned)lir::Operand::Type::Memory;
       tmpMask.setLowHighRegisterMasks(~static_cast<uint64_t>(0), ~static_cast<uint64_t>(0));
     }
   }
@@ -532,10 +532,10 @@ class MyArchitecture : public Architecture {
                           unsigned,
                           bool* thunk)
   {
-    aMask.typeMask = (1 << lir::RegisterOperand) | (1 << lir::ConstantOperand);
+    aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Constant);
     aMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
 
-    bMask.typeMask = (1 << lir::RegisterOperand);
+    bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
     bMask.setLowHighRegisterMasks(GPR_MASK, GPR_MASK);
 
     *thunk = false;
@@ -545,7 +545,7 @@ class MyArchitecture : public Architecture {
     case lir::ShiftRight:
     case lir::UnsignedShiftRight:
       if (bSize == 8)
-        aMask.typeMask = bMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       break;
 
     case lir::Add:
@@ -553,7 +553,7 @@ class MyArchitecture : public Architecture {
     case lir::Or:
     case lir::Xor:
     case lir::Multiply:
-      aMask.typeMask = bMask.typeMask = (1 << lir::RegisterOperand);
+      aMask.typeMask = bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       break;
 
     case lir::Divide:
@@ -567,7 +567,7 @@ class MyArchitecture : public Architecture {
     case lir::FloatMultiply:
     case lir::FloatDivide:
       if (vfpSupported()) {
-        bMask.typeMask = (1 << lir::RegisterOperand);
+        bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(FPR_MASK, FPR_MASK);
         bMask = aMask;
       } else {
@@ -586,7 +586,7 @@ class MyArchitecture : public Architecture {
     case lir::JumpIfFloatLessOrEqualOrUnordered:
     case lir::JumpIfFloatGreaterOrEqualOrUnordered:
       if (vfpSupported()) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(FPR_MASK, FPR_MASK);
         bMask = aMask;
       } else {
@@ -608,10 +608,10 @@ class MyArchitecture : public Architecture {
                                OperandMask& cMask)
   {
     if (isBranch(op)) {
-      cMask.typeMask = (1 << lir::ConstantOperand);
+      cMask.typeMask = (1 << (unsigned)lir::Operand::Type::Constant);
       cMask.setLowHighRegisterMasks(0, 0);
     } else {
-      cMask.typeMask = (1 << lir::RegisterOperand);
+      cMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       cMask.lowRegisterMask = bMask.lowRegisterMask;
       cMask.highRegisterMask = bMask.highRegisterMask;
     }
@@ -682,7 +682,7 @@ class MyAssembler : public Assembler {
   {
     struct Argument {
       unsigned size;
-      lir::OperandType type;
+      lir::Operand::Type type;
       lir::Operand* operand;
     };
     RUNTIME_ARRAY(Argument, arguments, argumentCount);
@@ -693,7 +693,7 @@ class MyAssembler : public Assembler {
     for (unsigned i = 0; i < argumentCount; ++i) {
       RUNTIME_ARRAY_BODY(arguments)[i].size = va_arg(a, unsigned);
       RUNTIME_ARRAY_BODY(arguments)[i].type
-          = static_cast<lir::OperandType>(va_arg(a, int));
+          = static_cast<lir::Operand::Type>(va_arg(a, int));
       RUNTIME_ARRAY_BODY(arguments)[i].operand = va_arg(a, lir::Operand*);
       footprint += ceilingDivide(RUNTIME_ARRAY_BODY(arguments)[i].size,
                                  TargetBytesPerWord);
@@ -713,7 +713,7 @@ class MyAssembler : public Assembler {
                           RUNTIME_ARRAY_BODY(arguments)[i].operand),
               OperandInfo(pad(RUNTIME_ARRAY_BODY(arguments)[i].size,
                               TargetBytesPerWord),
-                          lir::RegisterOperand,
+                          lir::Operand::Type::RegisterPair,
                           &dst));
 
         offset += ceilingDivide(RUNTIME_ARRAY_BODY(arguments)[i].size,
@@ -727,7 +727,7 @@ class MyAssembler : public Assembler {
                           RUNTIME_ARRAY_BODY(arguments)[i].operand),
               OperandInfo(pad(RUNTIME_ARRAY_BODY(arguments)[i].size,
                               TargetBytesPerWord),
-                          lir::MemoryOperand,
+                          lir::Operand::Type::Memory,
                           &dst));
 
         offset += ceilingDivide(RUNTIME_ARRAY_BODY(arguments)[i].size,
@@ -888,14 +888,14 @@ class MyAssembler : public Assembler {
     if (isBranch(op)) {
       assertT(&con, a.size == b.size);
       assertT(&con, c.size == TargetBytesPerWord);
-      assertT(&con, c.type == lir::ConstantOperand);
+      assertT(&con, c.type == lir::Operand::Type::Constant);
 
       arch_->con.branchOperations[branchIndex(&(arch_->con), a.type, b.type)](
           &con, op, a.size, a.operand, b.operand, c.operand);
     } else {
       assertT(&con, b.size == c.size);
-      assertT(&con, b.type == lir::RegisterOperand);
-      assertT(&con, c.type == lir::RegisterOperand);
+      assertT(&con, b.type == lir::Operand::Type::RegisterPair);
+      assertT(&con, c.type == lir::Operand::Type::RegisterPair);
 
       arch_->con.ternaryOperations[index(&(arch_->con), op, a.type)](
           &con, b.size, a.operand, b.operand, c.operand);
diff --git a/src/codegen/target/arm/context.h b/src/codegen/target/arm/context.h
index 45d937da9b..fde5a54a29 100644
--- a/src/codegen/target/arm/context.h
+++ b/src/codegen/target/arm/context.h
@@ -85,15 +85,15 @@ class ArchitectureContext {
   vm::System* s;
   OperationType operations[lir::OperationCount];
   UnaryOperationType
-      unaryOperations[lir::UnaryOperationCount * lir::OperandTypeCount];
+      unaryOperations[lir::UnaryOperationCount * lir::Operand::TypeCount];
   BinaryOperationType binaryOperations[lir::BinaryOperationCount
-                                       * lir::OperandTypeCount
-                                       * lir::OperandTypeCount];
+                                       * lir::Operand::TypeCount
+                                       * lir::Operand::TypeCount];
   TernaryOperationType ternaryOperations[lir::NonBranchTernaryOperationCount
-                                         * lir::OperandTypeCount];
+                                         * lir::Operand::TypeCount];
   BranchOperationType branchOperations[lir::BranchOperationCount
-                                       * lir::OperandTypeCount
-                                       * lir::OperandTypeCount];
+                                       * lir::Operand::TypeCount
+                                       * lir::Operand::TypeCount];
 };
 
 inline avian::util::Aborter* getAborter(Context* c)
diff --git a/src/codegen/target/arm/multimethod.cpp b/src/codegen/target/arm/multimethod.cpp
index 0ee2a642bc..c01c934e5b 100644
--- a/src/codegen/target/arm/multimethod.cpp
+++ b/src/codegen/target/arm/multimethod.cpp
@@ -22,16 +22,16 @@ using namespace util;
 
 unsigned index(ArchitectureContext*,
                lir::BinaryOperation operation,
-               lir::OperandType operand1,
-               lir::OperandType operand2)
+               lir::Operand::Type operand1,
+               lir::Operand::Type operand2)
 {
   return operation + (lir::BinaryOperationCount * operand1)
-         + (lir::BinaryOperationCount * lir::OperandTypeCount * operand2);
+         + (lir::BinaryOperationCount * lir::Operand::TypeCount * operand2);
 }
 
 unsigned index(ArchitectureContext* con UNUSED,
                lir::TernaryOperation operation,
-               lir::OperandType operand1)
+               lir::Operand::Type operand1)
 {
   assertT(con, not isBranch(operation));
 
@@ -39,18 +39,18 @@ unsigned index(ArchitectureContext* con UNUSED,
 }
 
 unsigned branchIndex(ArchitectureContext* con UNUSED,
-                     lir::OperandType operand1,
-                     lir::OperandType operand2)
+                     lir::Operand::Type operand1,
+                     lir::Operand::Type operand2)
 {
-  return operand1 + (lir::OperandTypeCount * operand2);
+  return operand1 + (lir::Operand::TypeCount * operand2);
 }
 
 void populateTables(ArchitectureContext* con)
 {
-  const lir::OperandType C = lir::ConstantOperand;
-  const lir::OperandType A = lir::AddressOperand;
-  const lir::OperandType R = lir::RegisterOperand;
-  const lir::OperandType M = lir::MemoryOperand;
+  const lir::Operand::Type C = lir::Operand::Type::Constant;
+  const lir::Operand::Type A = lir::Operand::Type::Address;
+  const lir::Operand::Type R = lir::Operand::Type::RegisterPair;
+  const lir::Operand::Type M = lir::Operand::Type::Memory;
 
   OperationType* zo = con->operations;
   UnaryOperationType* uo = con->unaryOperations;
diff --git a/src/codegen/target/arm/multimethod.h b/src/codegen/target/arm/multimethod.h
index 1949bf5486..f234385ee6 100644
--- a/src/codegen/target/arm/multimethod.h
+++ b/src/codegen/target/arm/multimethod.h
@@ -25,16 +25,16 @@ namespace arm {
 
 unsigned index(ArchitectureContext*,
                lir::BinaryOperation operation,
-               lir::OperandType operand1,
-               lir::OperandType operand2);
+               lir::Operand::Type operand1,
+               lir::Operand::Type operand2);
 
 unsigned index(ArchitectureContext* con UNUSED,
                lir::TernaryOperation operation,
-               lir::OperandType operand1);
+               lir::Operand::Type operand1);
 
 unsigned branchIndex(ArchitectureContext* con UNUSED,
-                     lir::OperandType operand1,
-                     lir::OperandType operand2);
+                     lir::Operand::Type operand1,
+                     lir::Operand::Type operand2);
 
 void populateTables(ArchitectureContext* con);
 
diff --git a/src/codegen/target/multimethod.h b/src/codegen/target/multimethod.h
index e5de2ca23c..965d16a402 100644
--- a/src/codegen/target/multimethod.h
+++ b/src/codegen/target/multimethod.h
@@ -17,9 +17,9 @@ namespace codegen {
 class Multimethod {
  public:
   inline static unsigned index(lir::UnaryOperation operation,
-                               lir::OperandType operand)
+                               lir::Operand::Type operand)
   {
-    return operation + (lir::UnaryOperationCount * operand);
+    return operation + (lir::UnaryOperationCount * (unsigned)operand);
   }
 };
 
diff --git a/src/codegen/target/x86/assembler.cpp b/src/codegen/target/x86/assembler.cpp
index 2bf5eaeb0a..4049683651 100644
--- a/src/codegen/target/x86/assembler.cpp
+++ b/src/codegen/target/x86/assembler.cpp
@@ -501,8 +501,8 @@ class MyArchitecture : public Architecture {
                     OperandMask& aMask,
                     bool* thunk)
   {
-    aMask.typeMask = (1 << lir::RegisterOperand) | (1 << lir::MemoryOperand)
-                     | (1 << lir::ConstantOperand);
+    aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Memory)
+                     | (1 << (unsigned)lir::Operand::Type::Constant);
     *thunk = false;
   }
 
@@ -518,13 +518,13 @@ class MyArchitecture : public Architecture {
 
     switch (op) {
     case lir::Negate:
-      aMask.typeMask = (1 << lir::RegisterOperand);
+      aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       aMask.setLowHighRegisterMasks(1 << rax, 1 << rdx);
       break;
 
     case lir::Absolute:
       if (aSize <= TargetBytesPerWord) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(1 << rax, 0);
       } else {
         *thunk = true;
@@ -533,7 +533,7 @@ class MyArchitecture : public Architecture {
 
     case lir::FloatAbsolute:
       if (useSSE(&c)) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
       } else {
         *thunk = true;
@@ -543,7 +543,7 @@ class MyArchitecture : public Architecture {
     case lir::FloatNegate:
       // floatNegateRR does not support doubles
       if (useSSE(&c) and aSize == 4 and bSize == 4) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(FloatRegisterMask, 0);
       } else {
         *thunk = true;
@@ -552,8 +552,8 @@ class MyArchitecture : public Architecture {
 
     case lir::FloatSquareRoot:
       if (useSSE(&c)) {
-        aMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::MemoryOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Memory);
         aMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
       } else {
         *thunk = true;
@@ -562,8 +562,8 @@ class MyArchitecture : public Architecture {
 
     case lir::Float2Float:
       if (useSSE(&c)) {
-        aMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::MemoryOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Memory);
         aMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
       } else {
         *thunk = true;
@@ -576,8 +576,8 @@ class MyArchitecture : public Architecture {
       // thunks or produce inline machine code which handles edge
       // cases properly.
       if (false and useSSE(&c) and bSize <= TargetBytesPerWord) {
-        aMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::MemoryOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Memory);
         aMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
       } else {
         *thunk = true;
@@ -586,8 +586,8 @@ class MyArchitecture : public Architecture {
 
     case lir::Int2Float:
       if (useSSE(&c) and aSize <= TargetBytesPerWord) {
-        aMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::MemoryOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Memory);
         aMask.setLowHighRegisterMasks(GeneralRegisterMask, GeneralRegisterMask);
       } else {
         *thunk = true;
@@ -600,14 +600,14 @@ class MyArchitecture : public Architecture {
 
       if (TargetBytesPerWord == 4) {
         if (aSize == 4 and bSize == 8) {
-          aMask.typeMask = (1 << lir::RegisterOperand)
-                           | (1 << lir::MemoryOperand);
+          aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                           | (1 << (unsigned)lir::Operand::Type::Memory);
           const uint32_t mask = GeneralRegisterMask
                                 & ~((1 << rax) | (1 << rdx));
           aMask.setLowHighRegisterMasks(mask, mask);
         } else if (aSize == 1 or bSize == 1) {
-          aMask.typeMask = (1 << lir::RegisterOperand)
-                           | (1 << lir::MemoryOperand);
+          aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                           | (1 << (unsigned)lir::Operand::Type::Memory);
           const uint32_t mask = (1 << rax) | (1 << rcx) | (1 << rdx)
                                 | (1 << rbx);
           aMask.setLowHighRegisterMasks(mask, mask);
@@ -631,18 +631,18 @@ class MyArchitecture : public Architecture {
 
     switch (op) {
     case lir::Absolute:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       bMask.setLowHighRegisterMasks(1 << rax, 0);
       break;
 
     case lir::FloatAbsolute:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       bMask.lowRegisterMask = aMask.lowRegisterMask;
       bMask.highRegisterMask = aMask.highRegisterMask;
       break;
 
     case lir::Negate:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       bMask.lowRegisterMask = aMask.lowRegisterMask;
       bMask.highRegisterMask = aMask.highRegisterMask;
       break;
@@ -651,30 +651,30 @@ class MyArchitecture : public Architecture {
     case lir::FloatSquareRoot:
     case lir::Float2Float:
     case lir::Int2Float:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       bMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
       break;
 
     case lir::Float2Int:
-      bMask.typeMask = (1 << lir::RegisterOperand);
+      bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       break;
 
     case lir::Move:
       if (aMask.typeMask
-          & ((1 << lir::MemoryOperand) | 1 << lir::AddressOperand)) {
-        bMask.typeMask = (1 << lir::RegisterOperand);
+          & ((1 << (unsigned)lir::Operand::Type::Memory) | 1 << (unsigned)lir::Operand::Type::Address)) {
+        bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         bMask.setLowHighRegisterMasks(GeneralRegisterMask | FloatRegisterMask, GeneralRegisterMask);
-      } else if (aMask.typeMask & (1 << lir::RegisterOperand)) {
-        bMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::MemoryOperand);
+      } else if (aMask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair)) {
+        bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Memory);
         if (aMask.lowRegisterMask & FloatRegisterMask) {
           bMask.setLowHighRegisterMasks(FloatRegisterMask, 0);
         } else {
           bMask.setLowHighRegisterMasks(GeneralRegisterMask, GeneralRegisterMask);
         }
       } else {
-        bMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::MemoryOperand);
+        bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Memory);
       }
 
       if (TargetBytesPerWord == 4) {
@@ -704,32 +704,32 @@ class MyArchitecture : public Architecture {
     tmpMask.typeMask = 0;
     tmpMask.setLowHighRegisterMasks(0, 0);
 
-    if (dstMask.typeMask & (1 << lir::MemoryOperand)) {
+    if (dstMask.typeMask & (1 << (unsigned)lir::Operand::Type::Memory)) {
       // can't move directly from memory to memory
-      srcMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::ConstantOperand);
-      tmpMask.typeMask = 1 << lir::RegisterOperand;
+      srcMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Constant);
+      tmpMask.typeMask = 1 << (unsigned)lir::Operand::Type::RegisterPair;
       tmpMask.setLowHighRegisterMasks(GeneralRegisterMask, GeneralRegisterMask);
-    } else if (dstMask.typeMask & (1 << lir::RegisterOperand)) {
+    } else if (dstMask.typeMask & (1 << (unsigned)lir::Operand::Type::RegisterPair)) {
       if (size > TargetBytesPerWord) {
         // can't move directly from FPR to GPR or vice-versa for
         // values larger than the GPR size
         if (dstMask.lowRegisterMask & FloatRegisterMask) {
           srcMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
-          tmpMask.typeMask = 1 << lir::MemoryOperand;
+          tmpMask.typeMask = 1 << (unsigned)lir::Operand::Type::Memory;
         } else if (dstMask.lowRegisterMask & GeneralRegisterMask) {
           srcMask.setLowHighRegisterMasks(GeneralRegisterMask, GeneralRegisterMask);
-          tmpMask.typeMask = 1 << lir::MemoryOperand;
+          tmpMask.typeMask = 1 << (unsigned)lir::Operand::Type::Memory;
         }
       }
       if (dstMask.lowRegisterMask & FloatRegisterMask) {
         // can't move directly from constant to FPR
-        srcMask.typeMask &= ~(1 << lir::ConstantOperand);
+        srcMask.typeMask &= ~(1 << (unsigned)lir::Operand::Type::Constant);
         if (size > TargetBytesPerWord) {
-          tmpMask.typeMask = 1 << lir::MemoryOperand;
+          tmpMask.typeMask = 1 << (unsigned)lir::Operand::Type::Memory;
         } else {
-          tmpMask.typeMask = (1 << lir::RegisterOperand)
-                             | (1 << lir::MemoryOperand);
+          tmpMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                             | (1 << (unsigned)lir::Operand::Type::Memory);
           tmpMask.setLowHighRegisterMasks(GeneralRegisterMask, GeneralRegisterMask);
         }
       }
@@ -744,10 +744,10 @@ class MyArchitecture : public Architecture {
                           unsigned,
                           bool* thunk)
   {
-    aMask.typeMask = (1 << lir::RegisterOperand) | (1 << lir::ConstantOperand);
+    aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair) | (1 << (unsigned)lir::Operand::Type::Constant);
     aMask.setLowHighRegisterMasks(GeneralRegisterMask, GeneralRegisterMask);
 
-    bMask.typeMask = (1 << lir::RegisterOperand);
+    bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
     bMask.setLowHighRegisterMasks(GeneralRegisterMask, GeneralRegisterMask);
 
     *thunk = false;
@@ -758,9 +758,9 @@ class MyArchitecture : public Architecture {
     case lir::FloatMultiply:
     case lir::FloatDivide:
       if (useSSE(&c)) {
-        aMask.typeMask = (1 << lir::RegisterOperand)
-                         | (1 << lir::MemoryOperand);
-        bMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair)
+                         | (1 << (unsigned)lir::Operand::Type::Memory);
+        bMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
 
         aMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
         bMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
@@ -788,7 +788,7 @@ class MyArchitecture : public Architecture {
       if (TargetBytesPerWord == 4 and aSize == 8) {
         *thunk = true;
       } else {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(GeneralRegisterMask & ~((1 << rax) | (1 << rdx)), 0);
         bMask.setLowHighRegisterMasks(1 << rax, 0);
       }
@@ -798,7 +798,7 @@ class MyArchitecture : public Architecture {
       if (TargetBytesPerWord == 4 and aSize == 8) {
         *thunk = true;
       } else {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(GeneralRegisterMask & ~((1 << rax) | (1 << rdx)), 0);
         bMask.setLowHighRegisterMasks(1 << rax, 0);
       }
@@ -829,7 +829,7 @@ class MyArchitecture : public Architecture {
     case lir::JumpIfFloatLessOrEqualOrUnordered:
     case lir::JumpIfFloatGreaterOrEqualOrUnordered:
       if (useSSE(&c)) {
-        aMask.typeMask = (1 << lir::RegisterOperand);
+        aMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
         aMask.setLowHighRegisterMasks(FloatRegisterMask, FloatRegisterMask);
         bMask.typeMask = aMask.typeMask;
         bMask.lowRegisterMask = aMask.lowRegisterMask;
@@ -853,10 +853,10 @@ class MyArchitecture : public Architecture {
                                OperandMask& cMask)
   {
     if (isBranch(op)) {
-      cMask.typeMask = (1 << lir::ConstantOperand);
+      cMask.typeMask = (1 << (unsigned)lir::Operand::Type::Constant);
       cMask.setLowHighRegisterMasks(0, 0);
     } else {
-      cMask.typeMask = (1 << lir::RegisterOperand);
+      cMask.typeMask = (1 << (unsigned)lir::Operand::Type::RegisterPair);
       cMask.lowRegisterMask = bMask.lowRegisterMask;
       cMask.highRegisterMask = bMask.highRegisterMask;
     }
@@ -918,8 +918,8 @@ class MyAssembler : public Assembler {
     lir::Register stack(rsp);
     lir::Memory stackDst(rbx, stackOffset);
     apply(lir::Move,
-          OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack),
-          OperandInfo(TargetBytesPerWord, lir::MemoryOperand, &stackDst));
+          OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack),
+          OperandInfo(TargetBytesPerWord, lir::Operand::Type::Memory, &stackDst));
   }
 
   virtual void pushFrame(unsigned argumentCount, ...)
@@ -927,7 +927,7 @@ class MyAssembler : public Assembler {
     // TODO: Argument should be replaced by OperandInfo...
     struct Argument {
       unsigned size;
-      lir::OperandType type;
+      lir::Operand::Type type;
       lir::Operand* operand;
     };
     RUNTIME_ARRAY(Argument, arguments, argumentCount);
@@ -937,7 +937,7 @@ class MyAssembler : public Assembler {
     for (unsigned i = 0; i < argumentCount; ++i) {
       RUNTIME_ARRAY_BODY(arguments)[i].size = va_arg(a, unsigned);
       RUNTIME_ARRAY_BODY(arguments)[i].type
-          = static_cast<lir::OperandType>(va_arg(a, int));
+          = static_cast<lir::Operand::Type>(va_arg(a, int));
       RUNTIME_ARRAY_BODY(arguments)[i].operand = va_arg(a, lir::Operand*);
       footprint += ceilingDivide(RUNTIME_ARRAY_BODY(arguments)[i].size,
                                  TargetBytesPerWord);
@@ -956,7 +956,7 @@ class MyAssembler : public Assembler {
                           RUNTIME_ARRAY_BODY(arguments)[i].operand),
               OperandInfo(pad(RUNTIME_ARRAY_BODY(arguments)[i].size,
                               TargetBytesPerWord),
-                          lir::RegisterOperand,
+                          lir::Operand::Type::RegisterPair,
                           &dst));
       } else {
         lir::Memory dst(rsp, offset * TargetBytesPerWord);
@@ -966,7 +966,7 @@ class MyAssembler : public Assembler {
                           RUNTIME_ARRAY_BODY(arguments)[i].operand),
               OperandInfo(pad(RUNTIME_ARRAY_BODY(arguments)[i].size,
                               TargetBytesPerWord),
-                          lir::MemoryOperand,
+                          lir::Operand::Type::Memory,
                           &dst));
         offset += ceilingDivide(RUNTIME_ARRAY_BODY(arguments)[i].size,
                                 TargetBytesPerWord);
@@ -983,17 +983,17 @@ class MyAssembler : public Assembler {
       pushR(&c, TargetBytesPerWord, &base);
 
       apply(lir::Move,
-            OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack),
-            OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &base));
+            OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack),
+            OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &base));
     }
 
     lir::Constant footprintConstant(
         resolvedPromise(&c, footprint * TargetBytesPerWord));
     apply(lir::Subtract,
           OperandInfo(
-              TargetBytesPerWord, lir::ConstantOperand, &footprintConstant),
-          OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack),
-          OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack));
+              TargetBytesPerWord, lir::Operand::Type::Constant, &footprintConstant),
+          OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack),
+          OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack));
   }
 
   virtual void adjustFrame(unsigned difference)
@@ -1003,9 +1003,9 @@ class MyAssembler : public Assembler {
         resolvedPromise(&c, difference * TargetBytesPerWord));
     apply(lir::Subtract,
           OperandInfo(
-              TargetBytesPerWord, lir::ConstantOperand, &differenceConstant),
-          OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack),
-          OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack));
+              TargetBytesPerWord, lir::Operand::Type::Constant, &differenceConstant),
+          OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack),
+          OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack));
   }
 
   virtual void popFrame(unsigned frameFootprint)
@@ -1014,8 +1014,8 @@ class MyAssembler : public Assembler {
       lir::Register base(rbp);
       lir::Register stack(rsp);
       apply(lir::Move,
-            OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &base),
-            OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack));
+            OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &base),
+            OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack));
 
       popR(&c, TargetBytesPerWord, &base);
     } else {
@@ -1023,9 +1023,9 @@ class MyAssembler : public Assembler {
       lir::Constant footprint(
           resolvedPromise(&c, frameFootprint * TargetBytesPerWord));
       apply(lir::Add,
-            OperandInfo(TargetBytesPerWord, lir::ConstantOperand, &footprint),
-            OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack),
-            OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &stack));
+            OperandInfo(TargetBytesPerWord, lir::Operand::Type::Constant, &footprint),
+            OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack),
+            OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &stack));
     }
   }
 
@@ -1157,7 +1157,7 @@ class MyAssembler : public Assembler {
     if (isBranch(op)) {
       assertT(&this->c, a.size == b.size);
       assertT(&this->c, c.size == TargetBytesPerWord);
-      assertT(&this->c, c.type == lir::ConstantOperand);
+      assertT(&this->c, c.type == lir::Operand::Type::Constant);
 
       arch_->c.branchOperations[branchIndex(&(arch_->c), a.type, b.type)](
           &this->c, op, a.size, a.operand, b.operand, c.operand);
diff --git a/src/codegen/target/x86/context.h b/src/codegen/target/x86/context.h
index 93a6f1cc5b..89f877ce1a 100644
--- a/src/codegen/target/x86/context.h
+++ b/src/codegen/target/x86/context.h
@@ -68,13 +68,13 @@ class ArchitectureContext {
   bool useNativeFeatures;
   OperationType operations[lir::OperationCount];
   UnaryOperationType
-      unaryOperations[lir::UnaryOperationCount * lir::OperandTypeCount];
+      unaryOperations[lir::UnaryOperationCount * lir::Operand::TypeCount];
   BinaryOperationType binaryOperations
       [(lir::BinaryOperationCount + lir::NonBranchTernaryOperationCount)
-       * lir::OperandTypeCount * lir::OperandTypeCount];
+       * lir::Operand::TypeCount * lir::Operand::TypeCount];
   BranchOperationType branchOperations[lir::BranchOperationCount
-                                       * lir::OperandTypeCount
-                                       * lir::OperandTypeCount];
+                                       * lir::Operand::TypeCount
+                                       * lir::Operand::TypeCount];
 };
 
 class Context {
diff --git a/src/codegen/target/x86/multimethod.cpp b/src/codegen/target/x86/multimethod.cpp
index 19e6135e1a..17bc3d91cc 100644
--- a/src/codegen/target/x86/multimethod.cpp
+++ b/src/codegen/target/x86/multimethod.cpp
@@ -28,42 +28,42 @@ using namespace util;
 
 unsigned index(ArchitectureContext*,
                lir::BinaryOperation operation,
-               lir::OperandType operand1,
-               lir::OperandType operand2)
+               lir::Operand::Type operand1,
+               lir::Operand::Type operand2)
 {
   return operation + ((lir::BinaryOperationCount
-                       + lir::NonBranchTernaryOperationCount) * operand1)
+                       + lir::NonBranchTernaryOperationCount) * (unsigned)operand1)
          + ((lir::BinaryOperationCount + lir::NonBranchTernaryOperationCount)
-            * lir::OperandTypeCount * operand2);
+            * lir::Operand::TypeCount * (unsigned)operand2);
 }
 
 unsigned index(ArchitectureContext* c UNUSED,
                lir::TernaryOperation operation,
-               lir::OperandType operand1,
-               lir::OperandType operand2)
+               lir::Operand::Type operand1,
+               lir::Operand::Type operand2)
 {
   assertT(c, not isBranch(operation));
 
   return lir::BinaryOperationCount + operation
          + ((lir::BinaryOperationCount + lir::NonBranchTernaryOperationCount)
-            * operand1)
+            * (unsigned)operand1)
          + ((lir::BinaryOperationCount + lir::NonBranchTernaryOperationCount)
-            * lir::OperandTypeCount * operand2);
+            * lir::Operand::TypeCount * (unsigned)operand2);
 }
 
 unsigned branchIndex(ArchitectureContext* c UNUSED,
-                     lir::OperandType operand1,
-                     lir::OperandType operand2)
+                     lir::Operand::Type operand1,
+                     lir::Operand::Type operand2)
 {
-  return operand1 + (lir::OperandTypeCount * operand2);
+  return (unsigned)operand1 + (lir::Operand::TypeCount * (unsigned)operand2);
 }
 
 void populateTables(ArchitectureContext* c)
 {
-  const lir::OperandType C = lir::ConstantOperand;
-  const lir::OperandType A = lir::AddressOperand;
-  const lir::OperandType R = lir::RegisterOperand;
-  const lir::OperandType M = lir::MemoryOperand;
+  const lir::Operand::Type C = lir::Operand::Type::Constant;
+  const lir::Operand::Type A = lir::Operand::Type::Address;
+  const lir::Operand::Type R = lir::Operand::Type::RegisterPair;
+  const lir::Operand::Type M = lir::Operand::Type::Memory;
 
   OperationType* zo = c->operations;
   UnaryOperationType* uo = c->unaryOperations;
diff --git a/src/codegen/target/x86/multimethod.h b/src/codegen/target/x86/multimethod.h
index e9a4b36de6..5816ccb543 100644
--- a/src/codegen/target/x86/multimethod.h
+++ b/src/codegen/target/x86/multimethod.h
@@ -23,17 +23,17 @@ class ArchitectureContext;
 
 unsigned index(ArchitectureContext*,
                lir::BinaryOperation operation,
-               lir::OperandType operand1,
-               lir::OperandType operand2);
+               lir::Operand::Type operand1,
+               lir::Operand::Type operand2);
 
 unsigned index(ArchitectureContext* c UNUSED,
                lir::TernaryOperation operation,
-               lir::OperandType operand1,
-               lir::OperandType operand2);
+               lir::Operand::Type operand1,
+               lir::Operand::Type operand2);
 
 unsigned branchIndex(ArchitectureContext* c UNUSED,
-                     lir::OperandType operand1,
-                     lir::OperandType operand2);
+                     lir::Operand::Type operand1,
+                     lir::Operand::Type operand2);
 
 void populateTables(ArchitectureContext* c);
 
diff --git a/src/compile.cpp b/src/compile.cpp
index b64d06f1c5..a3f6e47cae 100644
--- a/src/compile.cpp
+++ b/src/compile.cpp
@@ -9785,20 +9785,20 @@ void compileCall(MyThread* t, Context* c, ThunkIndex index, bool call = true)
     lir::Memory table(t->arch->thread(), TARGET_THREAD_THUNKTABLE);
     lir::Register scratch(t->arch->scratch());
     a->apply(lir::Move,
-             OperandInfo(TargetBytesPerWord, lir::MemoryOperand, &table),
-             OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &scratch));
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::Memory, &table),
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &scratch));
     lir::Memory proc(scratch.low, index * TargetBytesPerWord);
     a->apply(lir::Move,
-             OperandInfo(TargetBytesPerWord, lir::MemoryOperand, &proc),
-             OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &scratch));
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::Memory, &proc),
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &scratch));
     a->apply(call ? lir::Call : lir::Jump,
-             OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &scratch));
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &scratch));
   } else {
     lir::Constant proc(new (&c->zone) avian::codegen::ResolvedPromise(
         reinterpret_cast<intptr_t>(t->thunkTable[index])));
 
     a->apply(call ? lir::LongCall : lir::LongJump,
-             OperandInfo(TargetBytesPerWord, lir::ConstantOperand, &proc));
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::Constant, &proc));
   }
 }
 
@@ -9815,7 +9815,7 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
     p->thunks.default_.frameSavedOffset = a->length();
 
     lir::Register thread(t->arch->thread());
-    a->pushFrame(1, TargetBytesPerWord, lir::RegisterOperand, &thread);
+    a->pushFrame(1, TargetBytesPerWord, lir::Operand::Type::RegisterPair, &thread);
 
     compileCall(t, &context, compileMethodIndex);
 
@@ -9823,7 +9823,7 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
 
     lir::Register result(t->arch->returnLow());
     a->apply(lir::Jump,
-             OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &result));
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &result));
 
     p->thunks.default_.length = a->endBlock(false)->resolve(0, 0);
 
@@ -9843,17 +9843,17 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
 
     a->apply(lir::Move,
              OperandInfo(
-                 TargetBytesPerWord, lir::MemoryOperand, &virtualCallTargetSrc),
-             OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &class_));
+                 TargetBytesPerWord, lir::Operand::Type::Memory, &virtualCallTargetSrc),
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &class_));
 
     lir::Memory virtualCallTargetDst(t->arch->thread(),
                                      TARGET_THREAD_VIRTUALCALLTARGET);
 
     a->apply(
         lir::Move,
-        OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &class_),
+        OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &class_),
         OperandInfo(
-            TargetBytesPerWord, lir::MemoryOperand, &virtualCallTargetDst));
+            TargetBytesPerWord, lir::Operand::Type::Memory, &virtualCallTargetDst));
 
     lir::Register index(t->arch->virtualCallIndex());
     lir::Memory virtualCallIndex(t->arch->thread(),
@@ -9861,15 +9861,15 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
 
     a->apply(
         lir::Move,
-        OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &index),
-        OperandInfo(TargetBytesPerWord, lir::MemoryOperand, &virtualCallIndex));
+        OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &index),
+        OperandInfo(TargetBytesPerWord, lir::Operand::Type::Memory, &virtualCallIndex));
 
     a->saveFrame(TARGET_THREAD_STACK, TARGET_THREAD_IP);
 
     p->thunks.defaultVirtual.frameSavedOffset = a->length();
 
     lir::Register thread(t->arch->thread());
-    a->pushFrame(1, TargetBytesPerWord, lir::RegisterOperand, &thread);
+    a->pushFrame(1, TargetBytesPerWord, lir::Operand::Type::RegisterPair, &thread);
 
     compileCall(t, &context, compileVirtualMethodIndex);
 
@@ -9877,7 +9877,7 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
 
     lir::Register result(t->arch->returnLow());
     a->apply(lir::Jump,
-             OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &result));
+             OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &result));
 
     p->thunks.defaultVirtual.length = a->endBlock(false)->resolve(0, 0);
 
@@ -9894,7 +9894,7 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
     p->thunks.native.frameSavedOffset = a->length();
 
     lir::Register thread(t->arch->thread());
-    a->pushFrame(1, TargetBytesPerWord, lir::RegisterOperand, &thread);
+    a->pushFrame(1, TargetBytesPerWord, lir::Operand::Type::RegisterPair, &thread);
 
     compileCall(t, &context, invokeNativeIndex);
 
@@ -9916,7 +9916,7 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
     p->thunks.aioob.frameSavedOffset = a->length();
 
     lir::Register thread(t->arch->thread());
-    a->pushFrame(1, TargetBytesPerWord, lir::RegisterOperand, &thread);
+    a->pushFrame(1, TargetBytesPerWord, lir::Operand::Type::RegisterPair, &thread);
 
     compileCall(t, &context, throwArrayIndexOutOfBoundsIndex);
 
@@ -9935,7 +9935,7 @@ void compileThunks(MyThread* t, FixedAllocator* allocator)
     p->thunks.stackOverflow.frameSavedOffset = a->length();
 
     lir::Register thread(t->arch->thread());
-    a->pushFrame(1, TargetBytesPerWord, lir::RegisterOperand, &thread);
+    a->pushFrame(1, TargetBytesPerWord, lir::Operand::Type::RegisterPair, &thread);
 
     compileCall(t, &context, throwStackOverflowIndex);
 
@@ -10061,14 +10061,14 @@ uintptr_t compileVirtualThunk(MyThread* t, unsigned index, unsigned* size)
   lir::Register indexRegister(t->arch->virtualCallIndex());
   a->apply(
       lir::Move,
-      OperandInfo(TargetBytesPerWord, lir::ConstantOperand, &indexConstant),
-      OperandInfo(TargetBytesPerWord, lir::RegisterOperand, &indexRegister));
+      OperandInfo(TargetBytesPerWord, lir::Operand::Type::Constant, &indexConstant),
+      OperandInfo(TargetBytesPerWord, lir::Operand::Type::RegisterPair, &indexRegister));
 
   avian::codegen::ResolvedPromise defaultVirtualThunkPromise(
       defaultVirtualThunk(t));
   lir::Constant thunk(&defaultVirtualThunkPromise);
   a->apply(lir::Jump,
-           OperandInfo(TargetBytesPerWord, lir::ConstantOperand, &thunk));
+           OperandInfo(TargetBytesPerWord, lir::Operand::Type::Constant, &thunk));
 
   *size = a->endBlock(false)->resolve(0, 0);