[interpreter] Add output register to ToName

ToName was always generated with a subsequent Star, fuse them.
Requires a few changes in the peephole optimizer as ToName cannot be
elided as easily, but must be replaced by Star.

BUG=v8:4280
LOG=n

Review-Url: https://codereview.chromium.org/2169813002
Cr-Commit-Position: refs/heads/master@{#38019}

src/compiler/bytecode-graph-builder.cc

@@ -1304,18 +1304,19 @@ void BytecodeGraphBuilder::VisitTestInstanceOf() {
   BuildCompareOp(javascript()->InstanceOf());
 }
 
-void BytecodeGraphBuilder::BuildCastOperator(const Operator* js_op) {
-  FrameStateBeforeAndAfter states(this);
-  Node* node = NewNode(js_op, environment()->LookupAccumulator());
-  environment()->BindAccumulator(node, &states);
-}
-
 void BytecodeGraphBuilder::VisitToName() {
-  BuildCastOperator(javascript()->ToName());
+  FrameStateBeforeAndAfter states(this);
+  Node* value =
+      NewNode(javascript()->ToName(), environment()->LookupAccumulator());
+  environment()->BindRegister(bytecode_iterator().GetRegisterOperand(0), value,
+                              &states);
 }
 
 void BytecodeGraphBuilder::VisitToObject() {
-  BuildCastOperator(javascript()->ToObject());
+  FrameStateBeforeAndAfter states(this);
+  Node* node =
+      NewNode(javascript()->ToObject(), environment()->LookupAccumulator());
+  environment()->BindAccumulator(node, &states);
 }
 
 void BytecodeGraphBuilder::VisitToNumber() {

src/compiler/bytecode-graph-builder.h

@@ -128,7 +128,6 @@ class BytecodeGraphBuilder {
   void BuildBinaryOpWithImmediate(const Operator* op);
   void BuildCompareOp(const Operator* op);
   void BuildDelete(LanguageMode language_mode);
-  void BuildCastOperator(const Operator* op);
   void BuildForInPrepare();
   void BuildForInNext();
   void BuildInvokeIntrinsic();

src/interpreter/bytecode-array-builder.cc

@@ -388,8 +388,9 @@ BytecodeArrayBuilder& BytecodeArrayBuilder::CastAccumulatorToJSObject() {
   return *this;
 }
 
-BytecodeArrayBuilder& BytecodeArrayBuilder::CastAccumulatorToName() {
-  Output(Bytecode::kToName);
+BytecodeArrayBuilder& BytecodeArrayBuilder::CastAccumulatorToName(
+    Register out) {
+  Output(Bytecode::kToName, RegisterOperand(out));
   return *this;
 }
 

src/interpreter/bytecode-array-builder.h

@@ -212,11 +212,12 @@ class BytecodeArrayBuilder final : public ZoneObject {
   // Tests.
   BytecodeArrayBuilder& CompareOperation(Token::Value op, Register reg);
 
-  // Casts.
+  // Casts accumulator and stores result in accumulator.
   BytecodeArrayBuilder& CastAccumulatorToBoolean();
   BytecodeArrayBuilder& CastAccumulatorToJSObject();
-  BytecodeArrayBuilder& CastAccumulatorToName();
-  // Does not update the accumulator but stores to |out| instead.
+
+  // Casts accumulator and stores result in register |out|.
+  BytecodeArrayBuilder& CastAccumulatorToName(Register out);
   BytecodeArrayBuilder& CastAccumulatorToNumber(Register out);
 
   // Flow Control.

src/interpreter/bytecode-generator.cc

@@ -1448,7 +1448,7 @@ void BytecodeGenerator::VisitClassLiteralProperties(ClassLiteral* expr,
     }
 
     VisitForAccumulatorValue(property->key());
-    builder()->CastAccumulatorToName().StoreAccumulatorInRegister(key);
+    builder()->CastAccumulatorToName(key);
     // The static prototype property is read only. We handle the non computed
     // property name case in the parser. Since this is the only case where we
     // need to check for an own read only property we special case this so we do
@@ -1734,7 +1734,7 @@ void BytecodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
 
     builder()->MoveRegister(literal, literal_argument);
     VisitForAccumulatorValue(property->key());
-    builder()->CastAccumulatorToName().StoreAccumulatorInRegister(key);
+    builder()->CastAccumulatorToName(key);
     VisitForAccumulatorValue(property->value());
     builder()->StoreAccumulatorInRegister(value);
     VisitSetHomeObject(value, literal, property);

src/interpreter/bytecode-peephole-optimizer.cc

@@ -221,18 +221,6 @@ void BytecodePeepholeOptimizer::ElideCurrentIfOperand0MatchesAction(
   }
 }
 
-void BytecodePeepholeOptimizer::ElideCurrentIfLoadingNameConstantAction(
-    BytecodeNode* const node, const PeepholeActionAndData* action_data) {
-  DCHECK_EQ(last()->bytecode(), Bytecode::kLdaConstant);
-  DCHECK(!Bytecodes::IsJump(node->bytecode()));
-
-  if (GetConstantForIndexOperand(last(), 0)->IsName()) {
-    ElideCurrentAction(node);
-  } else {
-    DefaultAction(node);
-  }
-}
-
 void BytecodePeepholeOptimizer::ElideLastAction(
     BytecodeNode* const node, const PeepholeActionAndData* action_data) {
   DCHECK(LastIsValid());
@@ -256,7 +244,7 @@ void BytecodePeepholeOptimizer::ChangeBytecodeAction(
   DCHECK(LastIsValid());
   DCHECK(!Bytecodes::IsJump(node->bytecode()));
 
-  node->set_bytecode(action_data->bytecode);
+  node->replace_bytecode(action_data->bytecode);
   DefaultAction(node);
 }
 
@@ -301,6 +289,17 @@ void BytecodePeepholeOptimizer::
   }
 }
 
+void BytecodePeepholeOptimizer::TransformToStarIfLoadingNameConstantAction(
+    BytecodeNode* const node, const PeepholeActionAndData* action_data) {
+  DCHECK_EQ(last()->bytecode(), Bytecode::kLdaConstant);
+  DCHECK(!Bytecodes::IsJump(node->bytecode()));
+
+  if (GetConstantForIndexOperand(last(), 0)->IsName()) {
+    node->replace_bytecode(Bytecode::kStar);
+  }
+  DefaultAction(node);
+}
+
 void BytecodePeepholeOptimizer::DefaultJumpAction(
     BytecodeNode* const node, const PeepholeActionAndData* action_data) {
   DCHECK(LastIsValid());

src/interpreter/bytecode-peephole-table.h

@@ -11,18 +11,18 @@ namespace v8 {
 namespace internal {
 namespace interpreter {
 
-#define PEEPHOLE_NON_JUMP_ACTION_LIST(V)            \
-  V(DefaultAction)                                  \
-  V(UpdateLastAction)                               \
-  V(UpdateLastIfSourceInfoPresentAction)            \
-  V(ElideCurrentAction)                             \
-  V(ElideCurrentIfOperand0MatchesAction)            \
-  V(ElideCurrentIfLoadingNameConstantAction)        \
-  V(ElideLastAction)                                \
-  V(ChangeBytecodeAction)                           \
-  V(TransformLdaStarToLdrLdarAction)                \
-  V(TransformLdaSmiBinaryOpToBinaryOpWithSmiAction) \
-  V(TransformLdaZeroBinaryOpToBinaryOpWithZeroAction)
+#define PEEPHOLE_NON_JUMP_ACTION_LIST(V)              \
+  V(DefaultAction)                                    \
+  V(UpdateLastAction)                                 \
+  V(UpdateLastIfSourceInfoPresentAction)              \
+  V(ElideCurrentAction)                               \
+  V(ElideCurrentIfOperand0MatchesAction)              \
+  V(ElideLastAction)                                  \
+  V(ChangeBytecodeAction)                             \
+  V(TransformLdaStarToLdrLdarAction)                  \
+  V(TransformLdaSmiBinaryOpToBinaryOpWithSmiAction)   \
+  V(TransformLdaZeroBinaryOpToBinaryOpWithZeroAction) \
+  V(TransformToStarIfLoadingNameConstantAction)
 
 #define PEEPHOLE_JUMP_ACTION_LIST(V) \
   V(DefaultJumpAction)               \

src/interpreter/bytecode-pipeline.h

@@ -153,6 +153,12 @@ class BytecodeNode final : ZoneObject {
   BytecodeNode(const BytecodeNode& other);
   BytecodeNode& operator=(const BytecodeNode& other);
 
+  // Replace the bytecode of this node with |bytecode| and keep the operands.
+  void replace_bytecode(Bytecode bytecode) {
+    DCHECK_EQ(Bytecodes::NumberOfOperands(bytecode_),
+              Bytecodes::NumberOfOperands(bytecode));
+    bytecode_ = bytecode;
+  }
   void set_bytecode(Bytecode bytecode) {
     DCHECK_EQ(Bytecodes::NumberOfOperands(bytecode), 0);
     bytecode_ = bytecode;

src/interpreter/bytecodes.cc

@@ -505,7 +505,7 @@ bool Bytecodes::IsPrefixScalingBytecode(Bytecode bytecode) {
 
 // static
 bool Bytecodes::PutsNameInAccumulator(Bytecode bytecode) {
-  return bytecode == Bytecode::kToName || bytecode == Bytecode::kTypeOf;
+  return bytecode == Bytecode::kTypeOf;
 }
 
 // static

src/interpreter/bytecodes.h

@@ -211,7 +211,7 @@ namespace interpreter {
   V(TestIn, AccumulatorUse::kReadWrite, OperandType::kReg)                     \
                                                                                \
   /* Cast operators */                                                         \
-  V(ToName, AccumulatorUse::kReadWrite)                                        \
+  V(ToName, AccumulatorUse::kRead, OperandType::kRegOut)                       \
   V(ToNumber, AccumulatorUse::kRead, OperandType::kRegOut)                     \
   V(ToObject, AccumulatorUse::kReadWrite)                                      \
                                                                                \

src/interpreter/interpreter.cc

@@ -1026,7 +1026,9 @@ void Interpreter::DoUnaryOp(InterpreterAssembler* assembler) {
 //
 // Cast the object referenced by the accumulator to a name.
 void Interpreter::DoToName(InterpreterAssembler* assembler) {
-  DoUnaryOp(CodeFactory::ToName(isolate_), assembler);
+  Node* result = BuildUnaryOp(CodeFactory::ToName(isolate_), assembler);
+  __ StoreRegister(result, __ BytecodeOperandReg(0));
+  __ Dispatch();
 }
 
 // ToNumber

src/interpreter/mkpeephole.cc

@@ -106,13 +106,14 @@ PeepholeActionAndData PeepholeActionTableWriter::LookupActionAndData(
     }
   }
 
-  // ToName optimizations: remove unnecessary ToName bytecodes.
+  // ToName bytecodes can be replaced by Star with the same output register if
+  // the value in the accumulator is already a name.
   if (current == Bytecode::kToName) {
     if (last == Bytecode::kLdaConstant) {
-      return {PeepholeAction::kElideCurrentIfLoadingNameConstantAction,
+      return {PeepholeAction::kTransformToStarIfLoadingNameConstantAction,
               Bytecode::kIllegal};
     } else if (Bytecodes::PutsNameInAccumulator(last)) {
-      return {PeepholeAction::kElideCurrentAction, Bytecode::kIllegal};
+      return {PeepholeAction::kChangeBytecodeAction, Bytecode::kStar};
     }
   }
 

test/cctest/interpreter/bytecode_expectations/ClassDeclarations.golden

@@ -122,7 +122,7 @@ snippet: "
 "
 frame size: 10
 parameter count: 1
-bytecode array length: 126
+bytecode array length: 124
 bytecodes: [
                 B(CallRuntime), U16(Runtime::kNewFunctionContext), R(closure), U8(1),
                 B(PushContext), R(2),
@@ -147,8 +147,7 @@ bytecodes: [
                 B(Star), R(3),
                 B(LdrNamedProperty), R(3), U8(3), U8(1), R(4),
   /*   75 E> */ B(LdaContextSlot), R(context), U8(4),
-                B(ToName),
-                B(Star), R(6),
+                B(ToName), R(6),
                 B(CreateClosure), U8(4), U8(2),
                 B(Star), R(7),
                 B(LdaSmi), U8(2),
@@ -158,8 +157,7 @@ bytecodes: [
                 B(Mov), R(4), R(5),
                 B(CallRuntime), U16(Runtime::kDefineDataPropertyInLiteral), R(5), U8(5),
   /*  106 E> */ B(LdaContextSlot), R(context), U8(5),
-                B(ToName),
-                B(Star), R(6),
+                B(ToName), R(6),
                 B(LdaConstant), U8(3),
                 B(TestEqualStrict), R(6),
                 B(Mov), R(3), R(5),

test/cctest/interpreter/bytecode_expectations/ObjectLiterals.golden

@@ -299,7 +299,7 @@ snippet: "
 "
 frame size: 7
 parameter count: 1
-bytecode array length: 37
+bytecode array length: 36
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(LdaConstant), U8(0),
@@ -307,8 +307,7 @@ bytecodes: [
   /*   50 S> */ B(CreateObjectLiteral), U8(1), U8(0), U8(35),
                 B(Star), R(1),
                 B(Ldar), R(0),
-  /*   60 E> */ B(ToName),
-                B(Star), R(3),
+  /*   60 E> */ B(ToName), R(3),
                 B(LdaSmi), U8(1),
                 B(Star), R(4),
                 B(LdaZero),
@@ -333,7 +332,7 @@ snippet: "
 "
 frame size: 7
 parameter count: 1
-bytecode array length: 41
+bytecode array length: 40
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(LdaConstant), U8(0),
@@ -342,8 +341,7 @@ bytecodes: [
                 B(Star), R(1),
                 B(Ldar), R(0),
   /*   64 E> */ B(StaNamedPropertySloppy), R(1), U8(2), U8(1),
-  /*   68 E> */ B(ToName),
-                B(Star), R(3),
+  /*   68 E> */ B(ToName), R(3),
                 B(LdaSmi), U8(1),
                 B(Star), R(4),
                 B(LdaZero),
@@ -369,7 +367,7 @@ snippet: "
 "
 frame size: 7
 parameter count: 1
-bytecode array length: 54
+bytecode array length: 53
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(LdaConstant), U8(0),
@@ -377,8 +375,7 @@ bytecodes: [
   /*   50 S> */ B(CreateObjectLiteral), U8(1), U8(1), U8(35),
                 B(Star), R(1),
                 B(Ldar), R(0),
-  /*   60 E> */ B(ToName),
-                B(Star), R(3),
+  /*   60 E> */ B(ToName), R(3),
                 B(LdaSmi), U8(1),
                 B(Star), R(4),
                 B(LdaZero),
@@ -408,7 +405,7 @@ snippet: "
 "
 frame size: 7
 parameter count: 1
-bytecode array length: 77
+bytecode array length: 76
 bytecodes: [
   /*   30 E> */ B(StackCheck),
   /*   42 S> */ B(LdaConstant), U8(0),
@@ -416,8 +413,7 @@ bytecodes: [
   /*   50 S> */ B(CreateObjectLiteral), U8(1), U8(0), U8(35),
                 B(Star), R(1),
                 B(Ldar), R(0),
-  /*   60 E> */ B(ToName),
-                B(Star), R(3),
+  /*   60 E> */ B(ToName), R(3),
                 B(LdaConstant), U8(2),
                 B(Star), R(4),
                 B(LdaZero),

test/unittests/interpreter/bytecode-array-builder-unittest.cc

@@ -182,7 +182,7 @@ TEST_F(BytecodeArrayBuilderTest, AllBytecodesGenerated) {
   // Emit cast operator invocations.
   builder.CastAccumulatorToNumber(reg)
       .CastAccumulatorToJSObject()
-      .CastAccumulatorToName();
+      .CastAccumulatorToName(reg);
 
   // Emit control flow. Return must be the last instruction.
   BytecodeLabel start;

test/unittests/interpreter/bytecode-peephole-optimizer-unittest.cc

@@ -241,7 +241,7 @@ TEST_F(BytecodePeepholeOptimizerTest, StarRxLdarRxStatementStarRy) {
 
 TEST_F(BytecodePeepholeOptimizerTest, LdarToName) {
   BytecodeNode first(Bytecode::kLdar, Register(0).ToOperand());
-  BytecodeNode second(Bytecode::kToName);
+  BytecodeNode second(Bytecode::kToName, Register(0).ToOperand());
   optimizer()->Write(&first);
   CHECK_EQ(write_count(), 0);
   optimizer()->Write(&second);
@@ -252,26 +252,18 @@ TEST_F(BytecodePeepholeOptimizerTest, LdarToName) {
   CHECK_EQ(last_written(), second);
 }
 
-TEST_F(BytecodePeepholeOptimizerTest, ToNameToName) {
-  BytecodeNode first(Bytecode::kToName);
-  BytecodeNode second(Bytecode::kToName);
-  optimizer()->Write(&first);
-  optimizer()->Write(&second);
-  CHECK_EQ(write_count(), 0);
-  Flush();
-  CHECK_EQ(last_written(), first);
-  CHECK_EQ(write_count(), 1);
-}
-
 TEST_F(BytecodePeepholeOptimizerTest, TypeOfToName) {
   BytecodeNode first(Bytecode::kTypeOf);
-  BytecodeNode second(Bytecode::kToName);
+  BytecodeNode second(Bytecode::kToName, Register(0).ToOperand());
   optimizer()->Write(&first);
-  optimizer()->Write(&second);
   CHECK_EQ(write_count(), 0);
-  Flush();
+  optimizer()->Write(&second);
   CHECK_EQ(write_count(), 1);
   CHECK_EQ(last_written(), first);
+  Flush();
+  CHECK_EQ(write_count(), 2);
+  CHECK_EQ(last_written(), second);
+  CHECK_EQ(last_written().bytecode(), Bytecode::kStar);
 }
 
 TEST_F(BytecodePeepholeOptimizerTest, LdaConstantStringToName) {
@@ -279,20 +271,23 @@ TEST_F(BytecodePeepholeOptimizerTest, LdaConstantStringToName) {
       isolate()->factory()->NewStringFromStaticChars("optimizing");
   size_t index = constant_array()->Insert(word);
   BytecodeNode first(Bytecode::kLdaConstant, static_cast<uint32_t>(index));
-  BytecodeNode second(Bytecode::kToName);
+  BytecodeNode second(Bytecode::kToName, Register(0).ToOperand());
   optimizer()->Write(&first);
-  optimizer()->Write(&second);
   CHECK_EQ(write_count(), 0);
-  Flush();
+  optimizer()->Write(&second);
   CHECK_EQ(write_count(), 1);
   CHECK_EQ(last_written(), first);
+  Flush();
+  CHECK_EQ(write_count(), 2);
+  CHECK_EQ(last_written(), second);
+  CHECK_EQ(last_written().bytecode(), Bytecode::kStar);
 }
 
 TEST_F(BytecodePeepholeOptimizerTest, LdaConstantNumberToName) {
   Handle<Object> word = isolate()->factory()->NewNumber(0.380);
   size_t index = constant_array()->Insert(word);
   BytecodeNode first(Bytecode::kLdaConstant, static_cast<uint32_t>(index));
-  BytecodeNode second(Bytecode::kToName);
+  BytecodeNode second(Bytecode::kToName, Register(0).ToOperand());
   optimizer()->Write(&first);
   CHECK_EQ(write_count(), 0);
   optimizer()->Write(&second);