MIPS: Fix exception for assignment to uninitialised const.

src/mips64/full-codegen-mips64.cc

Index: src/mips64/full-codegen-mips64.cc
diff --git a/src/mips64/full-codegen-mips64.cc b/src/mips64/full-codegen-mips64.cc
index e5b4d9dc36c3827370232337b230e0362f7dc1bc..c58788ec17d217ee2b2ab468f237e45b1947947d 100644
--- a/src/mips64/full-codegen-mips64.cc
+++ b/src/mips64/full-codegen-mips64.cc
@@ -2704,23 +2704,6 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op) {
     __ li(StoreDescriptor::NameRegister(), Operand(var->name()));
     __ ld(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()) {
-      __ li(a0, Operand(var->name()));
-      __ Push(v0, cp, a0);  // Context and name.
-      __ CallRuntime(Runtime::kInitializeLegacyConstLookupSlot, 3);
-    } else {
-      DCHECK(var->IsStackAllocated() || var->IsContextSlot());
-      Label skip;
-      MemOperand location = VarOperand(var, a1);
-      __ ld(a2, location);
-      __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
-      __ Branch(&skip, ne, a2, Operand(at));
-      EmitStoreToStackLocalOrContextSlot(var, location);
-      __ bind(&skip);
-    }
 
   } else if (var->mode() == LET && op != Token::INIT_LET) {
     // Non-initializing assignment to let variable needs a write barrier.
@@ -2737,6 +2720,22 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op) {
     // Perform the assignment.
     __ 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, a1);
+    __ ld(a3, location);
+    __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
+    __ Branch(&const_error, ne, a3, Operand(at));
+    __ li(a3, Operand(var->name()));
+    __ push(a3);
+    __ 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.
@@ -2761,8 +2760,31 @@ 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->IsParameter());  // No const parameters.
+    if (var->IsLookupSlot()) {
+      __ li(a0, Operand(var->name()));
+      __ Push(v0, cp, a0);  // Context and name.
+      __ CallRuntime(Runtime::kInitializeLegacyConstLookupSlot, 3);
+    } else {
+      DCHECK(var->IsStackAllocated() || var->IsContextSlot());
+      Label skip;
+      MemOperand location = VarOperand(var, a1);
+      __ ld(a2, location);
+      __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
+      __ Branch(&skip, ne, a2, Operand(at));
+      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.
   }
 }