Fix exception for assignment to uninitialised const

src/arm/full-codegen-arm.cc

Index: src/arm/full-codegen-arm.cc
diff --git a/src/arm/full-codegen-arm.cc b/src/arm/full-codegen-arm.cc
index d451c084771845e1b26ec6570be36d4a556934d9..02f48b595985ea75e4d4c0a78a9f0578f313dcbc 100644
--- a/src/arm/full-codegen-arm.cc
+++ b/src/arm/full-codegen-arm.cc
@@ -2726,25 +2726,6 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op) {
     __ ldr(StoreDescriptor::ReceiverRegister(), GlobalObjectOperand());
     CallStoreIC();
 
-  } else if (op == Token::INIT_CONST_LEGACY) {
-    // Const initializers need a write barrier.
-    DCHECK(!var->IsParameter());  // No const parameters.
-    if (var->IsLookupSlot()) {
-      __ push(r0);
-      __ mov(r0, Operand(var->name()));
-      __ Push(cp, r0);  // Context and name.
-      __ CallRuntime(Runtime::kInitializeLegacyConstLookupSlot, 3);
-    } else {
-      DCHECK(var->IsStackAllocated() || var->IsContextSlot());
-      Label skip;
-      MemOperand location = VarOperand(var, r1);
-      __ ldr(r2, location);
-      __ CompareRoot(r2, Heap::kTheHoleValueRootIndex);
-      __ b(ne, &skip);
-      EmitStoreToStackLocalOrContextSlot(var, location);
-      __ bind(&skip);
-    }
-
   } else if (var->mode() == LET && op != Token::INIT_LET) {
     // Non-initializing assignment to let variable needs a write barrier.
     DCHECK(!var->IsLookupSlot());
@@ -2761,6 +2742,21 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op) {
     __ bind(&assign);
     EmitStoreToStackLocalOrContextSlot(var, location);
 
+  } else if (var->mode() == CONST && op != Token::INIT_CONST) {
+    // Assignment to const variable needs a write barrier.
+    DCHECK(!var->IsLookupSlot());
+    DCHECK(var->IsStackAllocated() || var->IsContextSlot());
+    Label const_error;
+    MemOperand location = VarOperand(var, r1);
+    __ ldr(r3, location);
+    __ CompareRoot(r3, Heap::kTheHoleValueRootIndex);
+    __ b(ne, &const_error);
+    __ mov(r3, Operand(var->name()));
+    __ push(r3);
+    __ CallRuntime(Runtime::kThrowReferenceError, 1);
+    __ bind(&const_error);
+    __ CallRuntime(Runtime::kThrowConstAssignError, 0);
+
   } else if (!var->is_const_mode() || op == Token::INIT_CONST) {
     if (var->IsLookupSlot()) {
       // Assignment to var.
@@ -2782,8 +2778,33 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op) {
       }
       EmitStoreToStackLocalOrContextSlot(var, location);
     }
-  } else if (IsSignallingAssignmentToConst(var, op, language_mode())) {
-    __ CallRuntime(Runtime::kThrowConstAssignError, 0);
+
+  } else if (op == Token::INIT_CONST_LEGACY) {
+    // Const initializers need a write barrier.
+    DCHECK(var->mode() == CONST_LEGACY);
+    DCHECK(!var->IsParameter());  // No const parameters.
+    if (var->IsLookupSlot()) {
+      __ push(r0);
+      __ mov(r0, Operand(var->name()));
+      __ Push(cp, r0);  // Context and name.
+      __ CallRuntime(Runtime::kInitializeLegacyConstLookupSlot, 3);
+    } else {
+      DCHECK(var->IsStackAllocated() || var->IsContextSlot());
+      Label skip;
+      MemOperand location = VarOperand(var, r1);
+      __ ldr(r2, location);
+      __ CompareRoot(r2, Heap::kTheHoleValueRootIndex);
+      __ b(ne, &skip);
+      EmitStoreToStackLocalOrContextSlot(var, location);
+      __ bind(&skip);
+    }
+
+  } else {
+    DCHECK(var->mode() == CONST_LEGACY && op != Token::INIT_CONST_LEGACY);
+    if (is_strict(language_mode())) {
+      __ CallRuntime(Runtime::kThrowConstAssignError, 0);
+    }
+    // Silently ignore store in sloppy mode.
   }
 }