Use Variable::binding_needs_init() to determine hole initialization

src/full-codegen/mips/full-codegen-mips.cc

Index: src/full-codegen/mips/full-codegen-mips.cc
diff --git a/src/full-codegen/mips/full-codegen-mips.cc b/src/full-codegen/mips/full-codegen-mips.cc
index 8d780a24177b430e278cf444807899636d4cf595..917eb6f00e5009093b7a0adbede05aaae06412a5 100644
--- a/src/full-codegen/mips/full-codegen-mips.cc
+++ b/src/full-codegen/mips/full-codegen-mips.cc
@@ -755,13 +755,8 @@ void FullCodeGenerator::EmitDebugCheckDeclarationContext(Variable* variable) {
 
 void FullCodeGenerator::VisitVariableDeclaration(
     VariableDeclaration* declaration) {
-  // If it was not possible to allocate the variable at compile time, we
-  // need to "declare" it at runtime to make sure it actually exists in the
-  // local context.
   VariableProxy* proxy = declaration->proxy();
-  VariableMode mode = declaration->mode();
   Variable* variable = proxy->var();
-  bool hole_init = mode == LET || mode == CONST;
   switch (variable->location()) {
     case VariableLocation::GLOBAL:
     case VariableLocation::UNALLOCATED: {
@@ -774,7 +769,7 @@ void FullCodeGenerator::VisitVariableDeclaration(
     }
     case VariableLocation::PARAMETER:
     case VariableLocation::LOCAL:
-      if (hole_init) {
+      if (variable->binding_needs_init()) {
         Comment cmnt(masm_, "[ VariableDeclaration");
         __ LoadRoot(t0, Heap::kTheHoleValueRootIndex);
         __ sw(t0, StackOperand(variable));
@@ -782,7 +777,7 @@ void FullCodeGenerator::VisitVariableDeclaration(
       break;
 
     case VariableLocation::CONTEXT:
-      if (hole_init) {
+      if (variable->binding_needs_init()) {
         Comment cmnt(masm_, "[ VariableDeclaration");
         EmitDebugCheckDeclarationContext(variable);
           __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
@@ -794,8 +789,8 @@ void FullCodeGenerator::VisitVariableDeclaration(
 
     case VariableLocation::LOOKUP: {
       Comment cmnt(masm_, "[ VariableDeclaration");
-      DCHECK_EQ(VAR, mode);
-      DCHECK(!hole_init);
+      DCHECK_EQ(VAR, variable->mode());
+      DCHECK(!variable->binding_needs_init());
       __ li(a2, Operand(variable->name()));
       __ Push(a2);
       __ CallRuntime(Runtime::kDeclareEvalVar);
@@ -1265,15 +1260,16 @@ void FullCodeGenerator::EmitDynamicLookupFastCase(VariableProxy* proxy,
   } else if (var->mode() == DYNAMIC_LOCAL) {
     Variable* local = var->local_if_not_shadowed();
     __ lw(v0, ContextSlotOperandCheckExtensions(local, slow));
-    if (local->mode() == LET || local->mode() == CONST) {
+    if (local->binding_needs_init()) {
       __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
       __ subu(at, v0, at);  // Sub as compare: at == 0 on eq.
       __ Branch(done, ne, at, Operand(zero_reg));
       __ li(a0, Operand(var->name()));
       __ push(a0);
       __ CallRuntime(Runtime::kThrowReferenceError);
+    } else {
+      __ Branch(done);
     }
-    __ Branch(done);
   }
 }
 
@@ -1316,20 +1312,17 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy,
       Comment cmnt(masm_, var->IsContextSlot() ? "[ Context variable"
                                                : "[ Stack variable");
       if (NeedsHoleCheckForLoad(proxy)) {
-        // Let and const need a read barrier.
+        // Throw a reference error when using an uninitialized let/const
+        // binding in harmony mode.
+        Label done;
         GetVar(v0, var);
         __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
         __ subu(at, v0, at);  // Sub as compare: at == 0 on eq.
-        if (var->mode() == LET || var->mode() == CONST) {
-          // Throw a reference error when using an uninitialized let/const
-          // binding in harmony mode.
-          Label done;
-          __ Branch(&done, ne, at, Operand(zero_reg));
-          __ li(a0, Operand(var->name()));
-          __ push(a0);
-          __ CallRuntime(Runtime::kThrowReferenceError);
-          __ bind(&done);
-        }
+        __ Branch(&done, ne, at, Operand(zero_reg));
+        __ li(a0, Operand(var->name()));
+        __ push(a0);
+        __ CallRuntime(Runtime::kThrowReferenceError);
+        __ bind(&done);
         context()->Plug(v0);
         break;
       }
@@ -2169,37 +2162,26 @@ void FullCodeGenerator::EmitVariableAssignment(Variable* var, Token::Value op,
     EmitLoadStoreICSlot(slot);
     CallStoreIC();
 
-  } else if (var->mode() == LET && op != Token::INIT) {
-    // Non-initializing assignment to let variable needs a write barrier.
-    DCHECK(!var->IsLookupSlot());
-    DCHECK(var->IsStackAllocated() || var->IsContextSlot());
-    Label assign;
-    MemOperand location = VarOperand(var, a1);
-    __ lw(a3, location);
-    __ LoadRoot(t0, Heap::kTheHoleValueRootIndex);
-    __ Branch(&assign, ne, a3, Operand(t0));
-    __ li(a3, Operand(var->name()));
-    __ push(a3);
-    __ CallRuntime(Runtime::kThrowReferenceError);
-    // Perform the assignment.
-    __ bind(&assign);
-    EmitStoreToStackLocalOrContextSlot(var, location);
-
-  } else if (var->mode() == CONST && op != Token::INIT) {
-    // Assignment to const variable needs a write barrier.
+  } else if (IsLexicalVariableMode(var->mode()) && op != Token::INIT) {
     DCHECK(!var->IsLookupSlot());
     DCHECK(var->IsStackAllocated() || var->IsContextSlot());
-    Label const_error;
     MemOperand location = VarOperand(var, a1);
-    __ lw(a3, location);
-    __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
-    __ Branch(&const_error, ne, a3, Operand(at));
-    __ li(a3, Operand(var->name()));
-    __ push(a3);
-    __ CallRuntime(Runtime::kThrowReferenceError);
-    __ bind(&const_error);
-    __ CallRuntime(Runtime::kThrowConstAssignError);
-
+    // Perform an initialization check for lexically declared variables.
+    if (var->binding_needs_init()) {
+      Label assign;
+      __ lw(a3, location);
+      __ LoadRoot(t0, Heap::kTheHoleValueRootIndex);
+      __ Branch(&assign, ne, a3, Operand(t0));
+      __ li(a3, Operand(var->name()));
+      __ push(a3);
+      __ CallRuntime(Runtime::kThrowReferenceError);
+      __ bind(&assign);
+    }
+    if (var->mode() == CONST) {
+      __ CallRuntime(Runtime::kThrowConstAssignError);
+    } else {
+      EmitStoreToStackLocalOrContextSlot(var, location);
+    }
   } else if (var->is_this() && var->mode() == CONST && op == Token::INIT) {
     // Initializing assignment to const {this} needs a write barrier.
     DCHECK(var->IsStackAllocated() || var->IsContextSlot());