Save/restore only live registers in the generator suspend/resume.

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/compiler/access-builder.h"
 #include "src/compiler/compiler-source-position-table.h"
@@ skipping 2259 matching lines @@
   index = NewNode(
       simplified()->SpeculativeNumberAdd(NumberOperationHint::kSignedSmall),
       index, jsgraph()->OneConstant());
   environment()->BindAccumulator(index, Environment::kAttachFrameState);
 }
 
 void BytecodeGraphBuilder::VisitSuspendGenerator() {
   Node* state = environment()->LookupAccumulator();
   Node* generator = environment()->LookupRegister(
       bytecode_iterator().GetRegisterOperand(0));
+  interpreter::Register first_reg = bytecode_iterator().GetRegisterOperand(1);
+  // We assume we are storing a range starting from index 0.
+  CHECK_EQ(0, first_reg.index());
+  int register_count =
+      static_cast<int>(bytecode_iterator().GetRegisterCountOperand(2));
   SuspendFlags flags = interpreter::SuspendGeneratorBytecodeFlags::Decode(
-      bytecode_iterator().GetFlagOperand(1));
+      bytecode_iterator().GetFlagOperand(3));
+
   // The offsets used by the bytecode iterator are relative to a different base
   // than what is used in the interpreter, hence the addition.
   Node* offset =
       jsgraph()->Constant(bytecode_iterator().current_offset() +
                           (BytecodeArray::kHeaderSize - kHeapObjectTag));
 
-  int register_count = environment()->register_count();
   int value_input_count = 3 + register_count;
 
   Node** value_inputs = local_zone()->NewArray<Node*>(value_input_count);
   value_inputs[0] = generator;
   value_inputs[1] = state;
   value_inputs[2] = offset;
   for (int i = 0; i < register_count; ++i) {
     value_inputs[3 + i] =
         environment()->LookupRegister(interpreter::Register(i));
   }
 
   MakeNode(javascript()->GeneratorStore(register_count, flags),
            value_input_count, value_inputs, false);
 }
 
-void BytecodeGraphBuilder::VisitResumeGenerator() {
+void BytecodeGraphBuilder::VisitRestoreGeneratorState() {
   Node* generator = environment()->LookupRegister(
       bytecode_iterator().GetRegisterOperand(0));
 
-  // Bijection between registers and array indices must match that used in
-  // InterpreterAssembler::ExportRegisterFile.
-  for (int i = 0; i < environment()->register_count(); ++i) {
-    Node* value = NewNode(javascript()->GeneratorRestoreRegister(i), generator);
-    environment()->BindRegister(interpreter::Register(i), value);
-  }
-
   Node* state =
       NewNode(javascript()->GeneratorRestoreContinuation(), generator);
 
-  environment()->BindAccumulator(state);
+  environment()->BindAccumulator(state, Environment::kAttachFrameState);
+}
+
+void BytecodeGraphBuilder::VisitRestoreGeneratorRegisters() {
+  Node* generator =
+      environment()->LookupRegister(bytecode_iterator().GetRegisterOperand(0));
+  interpreter::Register first_reg = bytecode_iterator().GetRegisterOperand(1);
+  // We assume we are restoring registers starting fromm index 0.
+  CHECK_EQ(0, first_reg.index());
+  int register_count =
+      static_cast<int>(bytecode_iterator().GetRegisterCountOperand(2));
+
+  // Bijection between registers and array indices must match that used in
+  // InterpreterAssembler::ExportRegisterFile.
+  for (int i = 0; i < register_count; ++i) {
+    Node* value = NewNode(javascript()->GeneratorRestoreRegister(i), generator);
+    environment()->BindRegister(interpreter::Register(i), value);
+  }
 }
 
 void BytecodeGraphBuilder::VisitWide() {
   // Consumed by the BytecodeArrayIterator.
   UNREACHABLE();
 }
 
 void BytecodeGraphBuilder::VisitExtraWide() {
   // Consumed by the BytecodeArrayIterator.
   UNREACHABLE();
@@ skipping 502 matching lines @@
         it->source_position().ScriptOffset(), start_position_.InliningId()));
     it->Advance();
   } else {
     DCHECK_GT(it->code_offset(), offset);
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8