Support for global var shortcuts in script contexts.

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/compiler.h"
 #include "src/compiler/ast-loop-assignment-analyzer.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/js-type-feedback.h"
@@ skipping 620 matching lines @@
   if (FLAG_trace_environment_liveness) {
     OFStream os(stdout);
     liveness_analyzer()->Print(os);
   }
 }
 
 
 // Gets the bailout id just before reading a variable proxy, but only for
 // unallocated variables.
 static BailoutId BeforeId(VariableProxy* proxy) {
-  return proxy->var()->location() == Variable::UNALLOCATED ? proxy->BeforeId()
-                                                           : BailoutId::None();
+  return proxy->var()->IsUnallocatedOrGlobalSlot() ? proxy->BeforeId()
+                                                   : BailoutId::None();
 }
 
 
 static const char* GetDebugParameterName(Zone* zone, Scope* scope, int index) {
 #if DEBUG
   const AstRawString* name = scope->parameter(index)->raw_name();
   if (name && name->length() > 0) {
     char* data = zone->NewArray<char>(name->length() + 1);
     data[name->length()] = 0;
     memcpy(data, name->raw_data(), name->length());
@@ skipping 397 matching lines @@
     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;
   switch (variable->location()) {
-    case Variable::UNALLOCATED: {
+    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;
     }
-    case Variable::PARAMETER:
-    case Variable::LOCAL:
+    case VariableLocation::PARAMETER:
+    case VariableLocation::LOCAL:
       if (hole_init) {
         Node* value = jsgraph()->TheHoleConstant();
         environment()->Bind(variable, value);
       }
       break;
-    case Variable::CONTEXT:
+    case VariableLocation::CONTEXT:
       if (hole_init) {
         Node* value = jsgraph()->TheHoleConstant();
         const Operator* op = javascript()->StoreContext(0, variable->index());
         NewNode(op, current_context(), value);
       }
       break;
-    case Variable::LOOKUP:
+    case VariableLocation::LOOKUP:
       UNIMPLEMENTED();
   }
 }
 
 
 void AstGraphBuilder::VisitFunctionDeclaration(FunctionDeclaration* decl) {
   Variable* variable = decl->proxy()->var();
   switch (variable->location()) {
-    case Variable::UNALLOCATED: {
+    case VariableLocation::GLOBAL:
+    case VariableLocation::UNALLOCATED: {
       Handle<SharedFunctionInfo> function = Compiler::GetSharedFunctionInfo(
           decl->fun(), info()->script(), info());
       // Check for stack-overflow exception.
       if (function.is_null()) return SetStackOverflow();
       globals()->push_back(variable->name());
       globals()->push_back(function);
       break;
     }
-    case Variable::PARAMETER:
-    case Variable::LOCAL: {
+    case VariableLocation::PARAMETER:
+    case VariableLocation::LOCAL: {
       VisitForValue(decl->fun());
       Node* value = environment()->Pop();
       environment()->Bind(variable, value);
       break;
     }
-    case Variable::CONTEXT: {
+    case VariableLocation::CONTEXT: {
       VisitForValue(decl->fun());
       Node* value = environment()->Pop();
       const Operator* op = javascript()->StoreContext(0, variable->index());
       NewNode(op, current_context(), value);
       break;
     }
-    case Variable::LOOKUP:
+    case VariableLocation::LOOKUP:
       UNIMPLEMENTED();
   }
 }
 
 
 void AstGraphBuilder::VisitImportDeclaration(ImportDeclaration* decl) {
   UNREACHABLE();
 }
 
 
@@ skipping 952 matching lines @@
 
   // Left-hand side can only be a property, a global or a variable slot.
   Property* property = expr->target()->AsProperty();
   LhsKind assign_type = Property::GetAssignType(property);
   bool needs_frame_state_before = true;
 
   // Evaluate LHS expression.
   switch (assign_type) {
     case VARIABLE: {
       Variable* variable = expr->target()->AsVariableProxy()->var();
-      if (variable->location() == Variable::PARAMETER ||
-          variable->location() == Variable::LOCAL ||
-          variable->location() == Variable::CONTEXT) {
+      if (variable->location() == VariableLocation::PARAMETER ||
+          variable->location() == VariableLocation::LOCAL ||
+          variable->location() == VariableLocation::CONTEXT) {
         needs_frame_state_before = false;
       }
       break;
     }
     case NAMED_PROPERTY:
       VisitForValue(property->obj());
       break;
     case KEYED_PROPERTY:
       VisitForValue(property->obj());
       VisitForValue(property->key());
@@ skipping 235 matching lines @@
       VectorSlotPair pair = CreateVectorSlotPair(proxy->VariableFeedbackSlot());
       FrameStateBeforeAndAfter states(this, BeforeId(proxy));
       callee_value =
           BuildVariableLoad(proxy->var(), expr->expression()->id(), states,
                             pair, OutputFrameStateCombine::Push());
       receiver_value = jsgraph()->UndefinedConstant();
       break;
     }
     case Call::LOOKUP_SLOT_CALL: {
       Variable* variable = callee->AsVariableProxy()->var();
-      DCHECK(variable->location() == Variable::LOOKUP);
+      DCHECK(variable->location() == VariableLocation::LOOKUP);
       Node* name = jsgraph()->Constant(variable->name());
       const Operator* op =
           javascript()->CallRuntime(Runtime::kLoadLookupSlot, 2);
       Node* pair = NewNode(op, current_context(), name);
       callee_value = NewNode(common()->Projection(0), pair);
       receiver_value = NewNode(common()->Projection(1), pair);
 
       PrepareFrameState(pair, expr->LookupId(),
                         OutputFrameStateCombine::Push(2));
       break;
@@ skipping 873 matching lines @@
 
 Node* AstGraphBuilder::BuildVariableLoad(Variable* variable,
                                          BailoutId bailout_id,
                                          FrameStateBeforeAndAfter& states,
                                          const VectorSlotPair& feedback,
                                          OutputFrameStateCombine combine,
                                          ContextualMode contextual_mode) {
   Node* the_hole = jsgraph()->TheHoleConstant();
   VariableMode mode = variable->mode();
   switch (variable->location()) {
-    case Variable::UNALLOCATED: {
+    case VariableLocation::GLOBAL:
+    case VariableLocation::UNALLOCATED: {
       // Global var, const, or let variable.
       Node* global = BuildLoadGlobalObject();
       Handle<Name> name = variable->name();
       Node* value = BuildGlobalLoad(global, name, feedback, contextual_mode);
       states.AddToNode(value, bailout_id, combine);
       return value;
     }
-    case Variable::PARAMETER:
-    case Variable::LOCAL: {
+    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);
         }
       } else 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 = BuildHoleCheckThrow(value, variable, value, bailout_id);
         }
       }
       return value;
     }
-    case Variable::CONTEXT: {
+    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) {
         // Perform check for uninitialized let/const variables.
         value = BuildHoleCheckThrow(value, variable, value, bailout_id);
       }
       return value;
     }
-    case Variable::LOOKUP: {
+    case VariableLocation::LOOKUP: {
       // Dynamic lookup of context variable (anywhere in the chain).
       Node* value = jsgraph()->TheHoleConstant();
       Handle<String> name = variable->name();
       if (mode == DYNAMIC_GLOBAL) {
         uint32_t check_bitset = ComputeBitsetForDynamicGlobal(variable);
         const Operator* op = javascript()->LoadDynamicGlobal(
             name, check_bitset, feedback, contextual_mode);
         value = NewNode(op, BuildLoadFeedbackVector(), current_context());
         states.AddToNode(value, bailout_id, combine);
       } else if (mode == DYNAMIC_LOCAL) {
         Variable* local = variable->local_if_not_shadowed();
-        DCHECK(local->location() == Variable::CONTEXT);  // Must be context.
+        DCHECK(local->location() ==
+               VariableLocation::CONTEXT);  // Must be context.
         int depth = current_scope()->ContextChainLength(local->scope());
         uint32_t check_bitset = ComputeBitsetForDynamicContext(variable);
         const Operator* op = javascript()->LoadDynamicContext(
             name, check_bitset, depth, local->index());
         value = NewNode(op, current_context());
         PrepareFrameState(value, bailout_id, combine);
         VariableMode local_mode = local->mode();
         if (local_mode == CONST_LEGACY) {
           // Perform check for uninitialized legacy const variables.
           Node* undefined = jsgraph()->UndefinedConstant();
@@ skipping 14 matching lines @@
   }
   UNREACHABLE();
   return NULL;
 }
 
 
 Node* AstGraphBuilder::BuildVariableDelete(Variable* variable,
                                            BailoutId bailout_id,
                                            OutputFrameStateCombine combine) {
   switch (variable->location()) {
-    case Variable::UNALLOCATED: {
+    case VariableLocation::GLOBAL:
+    case VariableLocation::UNALLOCATED: {
       // Global var, const, or let variable.
       Node* global = BuildLoadGlobalObject();
       Node* name = jsgraph()->Constant(variable->name());
       const Operator* op = javascript()->DeleteProperty(language_mode());
       Node* result = NewNode(op, global, name);
       PrepareFrameState(result, bailout_id, combine);
       return result;
     }
-    case Variable::PARAMETER:
-    case Variable::LOCAL:
-    case Variable::CONTEXT: {
+    case VariableLocation::PARAMETER:
+    case VariableLocation::LOCAL:
+    case VariableLocation::CONTEXT: {
       // Local var, const, or let variable or context variable.
       return jsgraph()->BooleanConstant(variable->HasThisName(isolate()));
     }
-    case Variable::LOOKUP: {
+    case VariableLocation::LOOKUP: {
       // Dynamic lookup of context variable (anywhere in the chain).
       Node* name = jsgraph()->Constant(variable->name());
       const Operator* op =
           javascript()->CallRuntime(Runtime::kDeleteLookupSlot, 2);
       Node* result = NewNode(op, current_context(), name);
       PrepareFrameState(result, bailout_id, combine);
       return result;
     }
   }
   UNREACHABLE();
   return NULL;
 }
 
 
 Node* AstGraphBuilder::BuildVariableAssignment(
     Variable* variable, Node* value, Token::Value op,
     const VectorSlotPair& feedback, BailoutId bailout_id,
     FrameStateBeforeAndAfter& states, OutputFrameStateCombine combine) {
   Node* the_hole = jsgraph()->TheHoleConstant();
   VariableMode mode = variable->mode();
   switch (variable->location()) {
-    case Variable::UNALLOCATED: {
+    case VariableLocation::GLOBAL:
+    case VariableLocation::UNALLOCATED: {
       // Global var, const, or let variable.
       Node* global = BuildLoadGlobalObject();
       Handle<Name> name = variable->name();
       Node* store = BuildGlobalStore(global, name, value, feedback,
                                      TypeFeedbackId::None());
       states.AddToNode(store, bailout_id, combine);
       return store;
     }
-    case Variable::PARAMETER:
-    case Variable::LOCAL:
+    case VariableLocation::PARAMETER:
+    case VariableLocation::LOCAL:
       // Local var, const, or let variable.
       if (mode == CONST_LEGACY && op == Token::INIT_CONST_LEGACY) {
         // 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_CONST_LEGACY) {
         // Non-initializing assignment to legacy const is
         // - exception in strict mode.
@@ skipping 18 matching lines @@
         Node* current = environment()->Lookup(variable);
         if (current->op() == the_hole->op()) {
           return BuildThrowReferenceError(variable, bailout_id);
         } else if (value->opcode() == IrOpcode::kPhi) {
           BuildHoleCheckThrow(current, variable, value, bailout_id);
         }
         return BuildThrowConstAssignError(bailout_id);
       }
       environment()->Bind(variable, value);
       return value;
-    case Variable::CONTEXT: {
+    case VariableLocation::CONTEXT: {
       // Context variable (potentially up the context chain).
       int depth = current_scope()->ContextChainLength(variable->scope());
       if (mode == CONST_LEGACY && op == Token::INIT_CONST_LEGACY) {
         // 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_CONST_LEGACY) {
         // Non-initializing assignment to legacy const is
@@ skipping 13 matching lines @@
         // Assignment to const is exception in all modes.
         const Operator* op =
             javascript()->LoadContext(depth, variable->index(), false);
         Node* current = NewNode(op, current_context());
         BuildHoleCheckThrow(current, variable, value, bailout_id);
         return BuildThrowConstAssignError(bailout_id);
       }
       const Operator* op = javascript()->StoreContext(depth, variable->index());
       return NewNode(op, current_context(), value);
     }
-    case Variable::LOOKUP: {
+    case VariableLocation::LOOKUP: {
       // Dynamic lookup of context variable (anywhere in the chain).
       Node* name = jsgraph()->Constant(variable->name());
       Node* language = jsgraph()->Constant(language_mode());
       // TODO(mstarzinger): Use Runtime::kInitializeLegacyConstLookupSlot for
       // initializations of const declarations.
       const Operator* op =
           javascript()->CallRuntime(Runtime::kStoreLookupSlot, 4);
       Node* store = NewNode(op, value, current_context(), name, language);
       PrepareFrameState(store, bailout_id, combine);
       return store;
@@ skipping 695 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