--- a/js/src/jit/MIR.h
+++ b/js/src/jit/MIR.h
@@ -5351,38 +5351,42 @@ class MMathFunction : public MUnaryInstr
 };
 
 class MAdd : public MBinaryArithInstruction {
   MAdd(MDefinition* left, MDefinition* right)
       : MBinaryArithInstruction(classOpcode, left, right) {
     setResultType(MIRType::Value);
   }
 
-  MAdd(MDefinition* left, MDefinition* right, MIRType type,
-       TruncateKind truncateKind = Truncate)
+  MAdd(MDefinition* left, MDefinition* right, MIRType type)
       : MAdd(left, right) {
     specialization_ = type;
     setResultType(type);
-    if (type == MIRType::Int32) {
-      setTruncateKind(truncateKind);
-      setCommutative();
-    }
+  }
 
   MAdd(MDefinition* left, MDefinition* right, TruncateKind truncateKind)
-      : MAdd(left, right) {
-    specialization_ = MIRType::Int32;
-    setResultType(MIRType::Int32);
+      : MAdd(left, right, MIRType::Int32) {
     setTruncateKind(truncateKind);
     setCommutative();
   }
 
  public:
   INSTRUCTION_HEADER(Add)
   TRIVIAL_NEW_WRAPPERS
 
+  static MAdd* NewWasm(TempAllocator& alloc, MDefinition* left,
+                       MDefinition* right, MIRType type) {
+    auto* ret = new (alloc) MAdd(left, right, type);
+    if (type == MIRType::Int32) {
+      ret->setTruncateKind(Truncate);
+      ret->setCommutative();
+    }
+    return ret;
+  }
+
   bool isFloat32Commutative() const override { return true; }
 
   double getIdentity() override { return 0; }
 
   bool fallible() const;
   void computeRange(TempAllocator& alloc) override;
   bool needTruncation(TruncateKind kind) override;
   void truncate() override;

--- a/js/src/wasm/WasmIonCompile.cpp
+++ b/js/src/wasm/WasmIonCompile.cpp
@@ -335,16 +335,25 @@ class FunctionCompiler {
     if (inDeadCode()) {
       return nullptr;
     }
     T* ins = T::New(alloc(), lhs, rhs, type);
     curBlock_->add(ins);
     return ins;
   }
 
+  MDefinition* add(MDefinition* lhs, MDefinition* rhs, MIRType type) {
+    if (inDeadCode()) {
+      return nullptr;
+    }
+    auto* ins = MAdd::NewWasm(alloc(), lhs, rhs, type);
+    curBlock_->add(ins);
+    return ins;
+  }
+
   bool mustPreserveNaN(MIRType type) {
     return IsFloatingPointType(type) && !env().isAsmJS();
   }
 
   MDefinition* sub(MDefinition* lhs, MDefinition* rhs, MIRType type) {
     if (inDeadCode()) {
       return nullptr;
     }
@@ -2518,17 +2527,17 @@ static bool EmitReinterpret(FunctionComp
 
 static bool EmitAdd(FunctionCompiler& f, ValType type, MIRType mirType) {
   MDefinition* lhs;
   MDefinition* rhs;
   if (!f.iter().readBinary(type, &lhs, &rhs)) {
     return false;
   }
 
-  f.iter().setResult(f.binary<MAdd>(lhs, rhs, mirType));
+  f.iter().setResult(f.add(lhs, rhs, mirType));
   return true;
 }
 
 static bool EmitSub(FunctionCompiler& f, ValType type, MIRType mirType) {
   MDefinition* lhs;
   MDefinition* rhs;
   if (!f.iter().readBinary(type, &lhs, &rhs)) {
     return false;