diff --git a/js/src/jit/AliasAnalysis.cpp b/js/src/jit/AliasAnalysis.cpp
index 2e803fdef0d12..8334d55dfecc1 100644
--- a/js/src/jit/AliasAnalysis.cpp
+++ b/js/src/jit/AliasAnalysis.cpp
@@ -187,8 +187,7 @@ bool AliasAnalysis::analyze() {
       def->setId(newId++);
     }
 
-    for (MInstructionIterator def(block->begin()),
-         end(block->begin(block->lastIns()));
+    for (MInstructionIterator def(block->begin()), end(block->end());
          def != end; ++def) {
       def->setId(newId++);
 
@@ -252,10 +251,6 @@ bool AliasAnalysis::analyze() {
       }
     }
 
-    // Renumber the last instruction, as the analysis depends on this and the
-    // order.
-    block->lastIns()->setId(newId++);
-
     if (block->isLoopBackedge()) {
       MOZ_ASSERT(loop_->loopHeader() == block->loopHeaderOfBackedge());
       JitSpew(JitSpew_Alias, "Processing loop backedge %u (header %u)",
diff --git a/js/src/jit/MIR.h b/js/src/jit/MIR.h
index 3238425ced834..2449e3588aa12 100644
--- a/js/src/jit/MIR.h
+++ b/js/src/jit/MIR.h
@@ -1724,6 +1724,8 @@ class MTableSwitch final : public MControlInstruction,
   }
 
   MDefinition* foldsTo(TempAllocator& alloc) override;
+
+  AliasSet getAliasSet() const override { return AliasSet::None(); }
 };
 
 template <size_t Arity, size_t Successors>
@@ -10238,6 +10240,8 @@ class MWasmReturn : public MAryControlInstruction<2, 0>,
  public:
   INSTRUCTION_HEADER(WasmReturn)
   TRIVIAL_NEW_WRAPPERS
+
+  AliasSet getAliasSet() const override { return AliasSet::None(); }
 };
 
 class MWasmReturnVoid : public MAryControlInstruction<1, 0>,
@@ -10250,6 +10254,8 @@ class MWasmReturnVoid : public MAryControlInstruction<1, 0>,
  public:
   INSTRUCTION_HEADER(WasmReturnVoid)
   TRIVIAL_NEW_WRAPPERS
+
+  AliasSet getAliasSet() const override { return AliasSet::None(); }
 };
 
 class MWasmStackArg : public MUnaryInstruction, public NoTypePolicy::Data {