[turbofan] Optimize variable loads in DYNAMIC_GLOBAL mode.

src/compiler/ast-graph-builder.h

 // 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.
 
 #ifndef V8_COMPILER_AST_GRAPH_BUILDER_H_
 #define V8_COMPILER_AST_GRAPH_BUILDER_H_
 
 #include "src/ast.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/liveness-analyzer.h"
@@ skipping 190 matching lines @@
 
   // The main node creation chokepoint. Adds context, frame state, effect,
   // and control dependencies depending on the operator.
   Node* MakeNode(const Operator* op, int value_input_count, Node** value_inputs,
                  bool incomplete);
 
   // Helper to indicate a node exits the function body.
   void UpdateControlDependencyToLeaveFunction(Node* exit);
 
   // Builds deoptimization for a given node.
-  void PrepareFrameState(
-      Node* node, BailoutId ast_id,
-      OutputFrameStateCombine combine = OutputFrameStateCombine::Ignore());
+  void PrepareFrameState(Node* node, BailoutId ast_id,
+                         OutputFrameStateCombine framestate_combine =
+                             OutputFrameStateCombine::Ignore());
 
   BitVector* GetVariablesAssignedInLoop(IterationStatement* stmt);
 
   // Check if the given statement is an OSR entry.
   // If so, record the stack height into the compilation and return {true}.
   bool CheckOsrEntry(IterationStatement* stmt);
 
   // Computes local variable liveness and replaces dead variables in
   // frame states with the undefined values.
   void ClearNonLiveSlotsInFrameStates();
@@ skipping 22 matching lines @@
   Node* BuildLocalScriptContext(Scope* scope);
   Node* BuildLocalBlockContext(Scope* scope);
 
   // Builder to create an arguments object if it is used.
   Node* BuildArgumentsObject(Variable* arguments);
 
   // Builder to create an array of rest parameters if used
   Node* BuildRestArgumentsArray(Variable* rest, int index);
 
   // Builders for variable load and assignment.
-  Node* BuildVariableAssignment(
-      FrameStateBeforeAndAfter& states, Variable* var, Node* value,
-      Token::Value op, BailoutId bailout_id,
-      OutputFrameStateCombine combine = OutputFrameStateCombine::Ignore());
+  Node* BuildVariableAssignment(Variable* var, Node* value, Token::Value op,
+                                BailoutId bailout_id,
+                                FrameStateBeforeAndAfter& states,
+                                OutputFrameStateCombine framestate_combine =
+                                    OutputFrameStateCombine::Ignore());
   Node* BuildVariableDelete(Variable* var, BailoutId bailout_id,
-                            OutputFrameStateCombine combine);
-  Node* BuildVariableLoad(FrameStateBeforeAndAfter& states, Variable* var,
-                          BailoutId bailout_id, const VectorSlotPair& feedback,
-                          OutputFrameStateCombine combine,
+                            OutputFrameStateCombine framestate_combine);
+  Node* BuildVariableLoad(Variable* var, BailoutId bailout_id,
+                          FrameStateBeforeAndAfter& states,
+                          const VectorSlotPair& feedback,
+                          OutputFrameStateCombine framestate_combine,
                           ContextualMode mode = CONTEXTUAL);
 
+  // Builders for variables using the global object.
+  Node* BuildGlobalVariableLoad(Variable* var, BailoutId bailout_id,
+                                FrameStateBeforeAndAfter& states,
+                                const VectorSlotPair& feedback,
+                                OutputFrameStateCombine framestate_combine,
+                                ContextualMode contextual_mode);
+
+  // Builders for variables using dynamic lookup.
+  Node* BuildDynamicVariableLoad(Variable* var, BailoutId bailout_id,
+                                 ContextualMode contextual_mode);
+
   // Builders for property loads and stores.
   Node* BuildKeyedLoad(Node* receiver, Node* key,
                        const VectorSlotPair& feedback);
   Node* BuildNamedLoad(Node* receiver, Handle<Name> name,
                        const VectorSlotPair& feedback,
                        ContextualMode mode = NOT_CONTEXTUAL);
   Node* BuildKeyedStore(Node* receiver, Node* key, Node* value,
                         TypeFeedbackId id);
   Node* BuildNamedStore(Node* receiver, Handle<Name>, Node* value,
                         TypeFeedbackId id);
@@ skipping 36 matching lines @@
   Node* BuildThrow(Node* exception_value);
 
   // Builders for binary operations.
   Node* BuildBinaryOp(Node* left, Node* right, Token::Value op);
 
   // Process arguments to a call by popping {arity} elements off the operand
   // stack and build a call node using the given call operator.
   Node* ProcessArguments(const Operator* op, int arity);
 
   // ===========================================================================
+  // The following build methods have the same contract as the above ones, but
+  // they can also return {NULL} to indicate that no fragment was built. Note
+  // that these are optimizations, disabling any of them should still produce
+  // correct graphs.
+
+  // Optimizers for variable load and assignment requiring dynamic lookup.
+  Node* TryDynamicGlobalVariableLoad(Variable* variable, BailoutId bailout_id,
+                                     FrameStateBeforeAndAfter& states,
+                                     const VectorSlotPair& feedback,
+                                     OutputFrameStateCombine framestate_combine,
+                                     ContextualMode contextual_mode);
+
+  // ===========================================================================
   // The following visitation methods all recursively visit a subtree of the
   // underlying AST and extent the graph. The operand stack is mutated in a way
   // consistent with other compilers:
   //  - Expressions pop operands and push result, depending on {AstContext}.
   //  - Statements keep the operand stack balanced.
 
   // Visit statements.
   void VisitIfNotNull(Statement* stmt);
 
   // Visit expressions.
@@ skipping 172 matching lines @@
 
   // Prepare environment to be used as loop header.
   void PrepareForLoop(BitVector* assigned, bool is_osr = false);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_AST_GRAPH_BUILDER_H_