[ignition] Add global lookup fast path to generated turbofan graph

src/compiler/bytecode-graph-builder.cc

 // Copyright 2015 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/bytecode-graph-builder.h"
 
 #include "src/ast/ast.h"
 #include "src/ast/scopes.h"
 #include "src/compilation-info.h"
 #include "src/compiler/bytecode-branch-analysis.h"
@@ skipping 768 matching lines @@
   Node* value = environment()->LookupAccumulator();
   environment()->BindRegister(bytecode_iterator().GetRegisterOperand(0), value);
 }
 
 void BytecodeGraphBuilder::VisitMov() {
   Node* value =
       environment()->LookupRegister(bytecode_iterator().GetRegisterOperand(0));
   environment()->BindRegister(bytecode_iterator().GetRegisterOperand(1), value);
 }
 
-Node* BytecodeGraphBuilder::BuildLoadGlobal(TypeofMode typeof_mode) {
-  VectorSlotPair feedback =
-      CreateVectorSlotPair(bytecode_iterator().GetIndexOperand(0));
+Node* BytecodeGraphBuilder::BuildLoadGlobal(int feedback_slot_operand,

[Michael Starzinger, 2016/09/29 14:52:25]

nit: Could we instead of passing the operand index just pass the operand value
(i.e. {int slod_id} in this case) directly? IMHO this would be easier to read. I
think the duplicated calls to {GetIndexOperand} are acceptable and they would be
closer to the actual visitation method.

[Leszek Swirski, 2016/09/29 15:40:18]

Done. I was on the fence about this too, thanks!

+                                            TypeofMode typeof_mode) {
+  VectorSlotPair feedback = CreateVectorSlotPair(
+      bytecode_iterator().GetIndexOperand(feedback_slot_operand));
   DCHECK_EQ(FeedbackVectorSlotKind::LOAD_GLOBAL_IC,
             feedback_vector()->GetKind(feedback.slot()));
   Handle<Name> name(feedback_vector()->GetName(feedback.slot()));
   const Operator* op = javascript()->LoadGlobal(name, feedback, typeof_mode);
   return NewNode(op, GetFunctionClosure());
 }
 
 void BytecodeGraphBuilder::VisitLdaGlobal() {
   FrameStateBeforeAndAfter states(this);
-  Node* node = BuildLoadGlobal(TypeofMode::NOT_INSIDE_TYPEOF);
+  Node* node = BuildLoadGlobal(0, TypeofMode::NOT_INSIDE_TYPEOF);
   environment()->BindAccumulator(node, &states);
 }
 
 void BytecodeGraphBuilder::VisitLdrGlobal() {
   FrameStateBeforeAndAfter states(this);
-  Node* node = BuildLoadGlobal(TypeofMode::NOT_INSIDE_TYPEOF);
+  Node* node = BuildLoadGlobal(0, TypeofMode::NOT_INSIDE_TYPEOF);
   environment()->BindRegister(bytecode_iterator().GetRegisterOperand(1), node,
                               &states);
 }
 
 void BytecodeGraphBuilder::VisitLdaGlobalInsideTypeof() {
   FrameStateBeforeAndAfter states(this);
-  Node* node = BuildLoadGlobal(TypeofMode::INSIDE_TYPEOF);
+  Node* node = BuildLoadGlobal(0, TypeofMode::INSIDE_TYPEOF);
   environment()->BindAccumulator(node, &states);
 }
 
 void BytecodeGraphBuilder::BuildStoreGlobal(LanguageMode language_mode) {
   FrameStateBeforeAndAfter states(this);
   Handle<Name> name =
       Handle<Name>::cast(bytecode_iterator().GetConstantForIndexOperand(0));
   VectorSlotPair feedback =
       CreateVectorSlotPair(bytecode_iterator().GetIndexOperand(1));
   Node* value = environment()->LookupAccumulator();
@@ skipping 56 matching lines @@
 }
 
 void BytecodeGraphBuilder::VisitLdaLookupSlot() {
   BuildLdaLookupSlot(TypeofMode::NOT_INSIDE_TYPEOF);
 }
 
 void BytecodeGraphBuilder::VisitLdaLookupSlotInsideTypeof() {
   BuildLdaLookupSlot(TypeofMode::INSIDE_TYPEOF);
 }
 
-void BytecodeGraphBuilder::BuildLdaLookupContextSlot(TypeofMode typeof_mode) {
-  uint32_t depth = bytecode_iterator().GetUnsignedImmediateOperand(2);
+BytecodeGraphBuilder::Environment* BytecodeGraphBuilder::CheckContextExtensions(
+    uint32_t depth) {
+  // Output environment where the context has an extension
+  Environment* slow_environment = nullptr;
 
-  // Check if any context in the depth has an extension.
-  Environment* slow_environment = nullptr;
+  DCHECK_GT(depth, 0u);
 
   // We only need to check up to the last-but-one depth, because the an eval in
   // the same scope as the variable itself has no way of shadowing it.
   for (uint32_t d = 0; d < depth; d++) {
     Node* extension_slot =
         NewNode(javascript()->LoadContext(d, Context::EXTENSION_INDEX, false),
                 environment()->Context());
 
     Node* check_no_extension =
         NewNode(javascript()->StrictEqual(CompareOperationHint::kAny),
@@ skipping 14 matching lines @@
     }
 
     {
       set_environment(true_environment);
       NewIfTrue();
       // Do nothing on if there is no extension, eventually falling through to
       // the fast path.
     }
   }
 
+  DCHECK(slow_environment != nullptr);

[Michael Starzinger, 2016/09/29 14:52:25]

nit: DCHECK_NOT_NULL

[Leszek Swirski, 2016/09/29 15:40:18]

Done.

+
+  return slow_environment;
+}
+
+void BytecodeGraphBuilder::BuildLdaLookupContextSlot(TypeofMode typeof_mode) {
+  uint32_t depth = bytecode_iterator().GetUnsignedImmediateOperand(2);
+
+  // Check if any context in the depth has an extension.
+  Environment* slow_environment = CheckContextExtensions(depth);
+
   // Fast path, do a context load.
   {
     uint32_t slot_index = bytecode_iterator().GetIndexOperand(1);
 
     const Operator* op = javascript()->LoadContext(depth, slot_index, false);
     Node* context = environment()->Context();
     environment()->BindAccumulator(NewNode(op, context));
     NewMerge();
   }
   Environment* fast_environment = environment();
@@ skipping 20 matching lines @@
 
 void BytecodeGraphBuilder::VisitLdaLookupContextSlot() {
   BuildLdaLookupContextSlot(TypeofMode::NOT_INSIDE_TYPEOF);
 }
 
 void BytecodeGraphBuilder::VisitLdaLookupContextSlotInsideTypeof() {
   BuildLdaLookupContextSlot(TypeofMode::INSIDE_TYPEOF);
 }
 
 void BytecodeGraphBuilder::BuildLdaLookupGlobalSlot(TypeofMode typeof_mode) {
-  // TODO(leszeks): Build the fast path here.
+  uint32_t depth = bytecode_iterator().GetUnsignedImmediateOperand(2);
+
+  // Check if any context in the depth has an extension.
+  Environment* slow_environment = CheckContextExtensions(depth);
+
+  // Fast path, do a global load.
+  {
+    FrameStateBeforeAndAfter states(this);
+    Node* node = BuildLoadGlobal(1, typeof_mode);
+    environment()->BindAccumulator(node, &states);
+
+    NewMerge();
+  }
+  Environment* fast_environment = environment();
 
   // Slow path, do a runtime load lookup.
+  set_environment(slow_environment);
   {
     FrameStateBeforeAndAfter states(this);
 
     Node* name =
         jsgraph()->Constant(bytecode_iterator().GetConstantForIndexOperand(0));
 
     const Operator* op =
         javascript()->CallRuntime(typeof_mode == TypeofMode::NOT_INSIDE_TYPEOF
                                       ? Runtime::kLoadLookupSlot
                                       : Runtime::kLoadLookupSlotInsideTypeof);
     Node* value = NewNode(op, name);
     environment()->BindAccumulator(value, &states);
   }
+
+  fast_environment->Merge(environment());
+  set_environment(fast_environment);
 }
 
 void BytecodeGraphBuilder::VisitLdaLookupGlobalSlot() {
   BuildLdaLookupGlobalSlot(TypeofMode::NOT_INSIDE_TYPEOF);
 }
 
 void BytecodeGraphBuilder::VisitLdaLookupGlobalSlotInsideTypeof() {
   BuildLdaLookupGlobalSlot(TypeofMode::INSIDE_TYPEOF);
 }
 
@@ skipping 1193 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