Fix exception for assignment to uninitialised const

src/x64/full-codegen-x64.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 2617 matching lines @@
 
 
 void FullCodeGenerator::EmitVariableAssignment(Variable* var,
                                                Token::Value op) {
   if (var->IsUnallocated()) {
     // Global var, const, or let.
     __ Move(StoreDescriptor::NameRegister(), var->name());
     __ movp(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(rax);
-      __ Push(rsi);
-      __ Push(var->name());
-      __ CallRuntime(Runtime::kInitializeLegacyConstLookupSlot, 3);
-    } else {
-      DCHECK(var->IsStackLocal() || var->IsContextSlot());
-      Label skip;
-      MemOperand location = VarOperand(var, rcx);
-      __ movp(rdx, location);
-      __ CompareRoot(rdx, Heap::kTheHoleValueRootIndex);
-      __ j(not_equal, &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());
     DCHECK(var->IsStackAllocated() || var->IsContextSlot());
     Label assign;
     MemOperand location = VarOperand(var, rcx);
     __ movp(rdx, location);
     __ CompareRoot(rdx, Heap::kTheHoleValueRootIndex);
     __ j(not_equal, &assign, Label::kNear);
     __ Push(var->name());
     __ CallRuntime(Runtime::kThrowReferenceError, 1);
     __ 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, rcx);
+    __ movp(rdx, location);
+    __ CompareRoot(rdx, Heap::kTheHoleValueRootIndex);
+    __ j(not_equal, &const_error, Label::kNear);
+    __ Push(var->name());
+    __ 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.
       __ Push(rax);  // Value.
       __ Push(rsi);  // Context.
       __ Push(var->name());
       __ Push(Smi::FromInt(language_mode()));
       __ CallRuntime(Runtime::kStoreLookupSlot, 4);
     } else {
       // Assignment to var or initializing assignment to let/const in harmony
       // mode.
       DCHECK(var->IsStackAllocated() || var->IsContextSlot());
       MemOperand location = VarOperand(var, rcx);
       if (generate_debug_code_ && op == Token::INIT_LET) {
         // Check for an uninitialized let binding.
         __ movp(rdx, location);
         __ CompareRoot(rdx, Heap::kTheHoleValueRootIndex);
         __ Check(equal, kLetBindingReInitialization);
       }
       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(rax);
+      __ Push(rsi);
+      __ Push(var->name());
+      __ CallRuntime(Runtime::kInitializeLegacyConstLookupSlot, 3);
+    } else {
+      DCHECK(var->IsStackLocal() || var->IsContextSlot());
+      Label skip;
+      MemOperand location = VarOperand(var, rcx);
+      __ movp(rdx, location);
+      __ CompareRoot(rdx, Heap::kTheHoleValueRootIndex);
+      __ j(not_equal, &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.
   }
 }
 
 
 void FullCodeGenerator::EmitNamedPropertyAssignment(Assignment* expr) {
   // Assignment to a property, using a named store IC.
   Property* prop = expr->target()->AsProperty();
   DCHECK(prop != NULL);
   DCHECK(prop->key()->IsLiteral());
 
@@ skipping 2682 matching lines @@
   DCHECK_EQ(isolate->builtins()->OsrAfterStackCheck()->entry(),
             Assembler::target_address_at(call_target_address,
                                          unoptimized_code));
   return OSR_AFTER_STACK_CHECK;
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64