Remove all non-function-name uses of CONST_LEGACY

src/compiler/ast-graph-builder.cc

 // Copyright 2014 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/compiler/ast-graph-builder.h"
 
 #include "src/ast/scopes.h"
 #include "src/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
@@ skipping 1065 matching lines @@
     expr->Accept(this);
   } else {
     ast_context()->ProduceValue(jsgraph()->UndefinedConstant());
   }
 }
 
 
 void AstGraphBuilder::VisitVariableDeclaration(VariableDeclaration* decl) {
   Variable* variable = decl->proxy()->var();
   VariableMode mode = decl->mode();
-  bool hole_init = mode == CONST || mode == CONST_LEGACY || mode == LET;
+  bool hole_init = mode == CONST || mode == LET;
   switch (variable->location()) {
     case VariableLocation::GLOBAL:
     case VariableLocation::UNALLOCATED: {
       Handle<Oddball> value = variable->binding_needs_init()
                                   ? isolate()->factory()->the_hole_value()
                                   : isolate()->factory()->undefined_value();
       globals()->push_back(variable->name());
       globals()->push_back(value);
       break;
     }
@@ skipping 2272 matching lines @@
       Handle<Name> name = variable->name();
       if (Node* node = TryLoadGlobalConstant(name)) return node;
       Node* value = BuildGlobalLoad(name, feedback, typeof_mode);
       states.AddToNode(value, bailout_id, combine);
       return value;
     }
     case VariableLocation::PARAMETER:
     case VariableLocation::LOCAL: {
       // Local var, const, or let variable.
       Node* value = environment()->Lookup(variable);
-      if (mode == CONST_LEGACY) {
-        // Perform check for uninitialized legacy const variables.
-        if (value->op() == the_hole->op()) {
-          value = jsgraph()->UndefinedConstant();
-        } else if (value->opcode() == IrOpcode::kPhi) {
-          Node* undefined = jsgraph()->UndefinedConstant();
-          value = BuildHoleCheckSilent(value, undefined, value);

[Michael Starzinger, 2016/04/18 22:49:16]

There should be no more call-sites of BuildHoleCheckSilent left, can we remove
it as well (both implementation and declaration in header file)?

[adamk, 2016/04/18 23:15:34]

Done. Also removed a few analogous bits from hydrogen-instructions.h.

-        }
-      } else if (mode == LET || mode == CONST) {
+      if (mode == LET || mode == CONST) {
         // Perform check for uninitialized let/const variables.
         if (value->op() == the_hole->op()) {
           value = BuildThrowReferenceError(variable, bailout_id);
         } else if (value->opcode() == IrOpcode::kPhi) {
           value = BuildHoleCheckThenThrow(value, variable, value, bailout_id);
         }
       }
       return value;
     }
     case VariableLocation::CONTEXT: {
       // Context variable (potentially up the context chain).
       int depth = current_scope()->ContextChainLength(variable->scope());
       bool immutable = variable->maybe_assigned() == kNotAssigned;
       const Operator* op =
           javascript()->LoadContext(depth, variable->index(), immutable);
       Node* value = NewNode(op, current_context());
       // TODO(titzer): initialization checks are redundant for already
       // initialized immutable context loads, but only specialization knows.
       // Maybe specializer should be a parameter to the graph builder?
-      if (mode == CONST_LEGACY) {
-        // Perform check for uninitialized legacy const variables.
-        Node* undefined = jsgraph()->UndefinedConstant();
-        value = BuildHoleCheckSilent(value, undefined, value);
-      } else if (mode == LET || mode == CONST) {
+      if (mode == LET || mode == CONST) {
         // Perform check for uninitialized let/const variables.
         value = BuildHoleCheckThenThrow(value, variable, value, bailout_id);
       }
       return value;
     }
     case VariableLocation::LOOKUP: {
       // Dynamic lookup of context variable (anywhere in the chain).
       Handle<String> name = variable->name();
       if (Node* node =
               TryLoadDynamicVariable(variable, name, bailout_id, states,
@@ skipping 56 matching lines @@
     case VariableLocation::UNALLOCATED: {
       // Global var, const, or let variable.
       Handle<Name> name = variable->name();
       Node* store = BuildGlobalStore(name, value, feedback);
       states.AddToNode(store, bailout_id, combine);
       return store;
     }
     case VariableLocation::PARAMETER:
     case VariableLocation::LOCAL:
       // Local var, const, or let variable.
-      if (mode == CONST_LEGACY && op == Token::INIT) {
-        // Perform an initialization check for legacy const variables.
-        Node* current = environment()->Lookup(variable);
-        if (current->op() != the_hole->op()) {
-          value = BuildHoleCheckSilent(current, value, current);
-        }
-      } else if (mode == CONST_LEGACY && op != Token::INIT) {
+      if (mode == CONST_LEGACY && op != Token::INIT) {
         // Non-initializing assignment to legacy const is
         // - exception in strict mode.
         // - ignored in sloppy mode.
         if (is_strict(language_mode())) {
           return BuildThrowConstAssignError(bailout_id);
         }
         return value;
       } else if (mode == LET && op == Token::INIT) {
         // No initialization check needed because scoping guarantees it. Note
         // that we still perform a lookup to keep the variable live, because
@@ skipping 24 matching lines @@
         } else if (current->opcode() == IrOpcode::kPhi) {
           BuildHoleCheckThenThrow(current, variable, value, bailout_id);
         }
         return BuildThrowConstAssignError(bailout_id);
       }
       environment()->Bind(variable, value);
       return value;
     case VariableLocation::CONTEXT: {
       // Context variable (potentially up the context chain).
       int depth = current_scope()->ContextChainLength(variable->scope());
-      if (mode == CONST_LEGACY && op == Token::INIT) {
-        // Perform an initialization check for legacy const variables.
-        const Operator* op =
-            javascript()->LoadContext(depth, variable->index(), false);
-        Node* current = NewNode(op, current_context());
-        value = BuildHoleCheckSilent(current, value, current);
-      } else if (mode == CONST_LEGACY && op != Token::INIT) {
+      if (mode == CONST_LEGACY && op != Token::INIT) {
         // Non-initializing assignment to legacy const is
         // - exception in strict mode.
         // - ignored in sloppy mode.
         if (is_strict(language_mode())) {
           return BuildThrowConstAssignError(bailout_id);
         }
         return value;
       } else if (mode == LET && op != Token::INIT) {
         // Perform an initialization check for let declared variables.
         const Operator* op =
@@ skipping 17 matching lines @@
         Node* current = NewNode(op, current_context());
         BuildHoleCheckThenThrow(current, variable, value, bailout_id);
         return BuildThrowConstAssignError(bailout_id);
       }
       const Operator* op = javascript()->StoreContext(depth, variable->index());
       return NewNode(op, current_context(), value);
     }
     case VariableLocation::LOOKUP: {
       // Dynamic lookup of context variable (anywhere in the chain).
       Handle<Name> name = variable->name();
-      // TODO(mstarzinger): Use Runtime::kInitializeLegacyConstLookupSlot for
-      // initializations of const declarations.
       Node* store = BuildDynamicStore(name, value);
       PrepareFrameState(store, bailout_id, combine);
       return store;
     }
   }
   UNREACHABLE();
   return nullptr;
 }
 
 
@@ skipping 776 matching lines @@
     // Phi does not exist yet, introduce one.
     value = NewPhi(inputs, value, control);
     value->ReplaceInput(inputs - 1, other);
   }
   return value;
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8