[Interpreter] Move ToName elision into BytecodeGenerator.

Moves the ToName elision out of the peephole optimizer and into the
BytecodeGenerator.

BUG=v8:6194

Change-Id: Ic355adbe21f967dc5d52babdd37100a260c62c26
Reviewed-on: https://chromium-review.googlesource.com/467466
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Cr-Commit-Position: refs/heads/master@{#44427}

src/interpreter/bytecode-generator.cc

@@ -1555,13 +1555,7 @@ void BytecodeGenerator::VisitClassLiteralProperties(ClassLiteral* expr,
       old_receiver = new_receiver;
     }
 
-    if (property->key()->IsStringLiteral()) {
-      VisitForRegisterValue(property->key(), key);
-    } else {
-      VisitForAccumulatorValue(property->key());
-      builder()->ConvertAccumulatorToName(key);
-    }
-
+    BuildLoadPropertyKey(property, key);
     if (property->is_static() && property->is_computed_name()) {
       // 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
@@ -1825,9 +1819,7 @@ void BytecodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
       case ObjectLiteral::Property::COMPUTED:
       case ObjectLiteral::Property::MATERIALIZED_LITERAL: {
         Register key = register_allocator()->NewRegister();
-        VisitForAccumulatorValue(property->key());
-        builder()->ConvertAccumulatorToName(key);
-
+        BuildLoadPropertyKey(property, key);
         Register value = VisitForRegisterValue(property->value());
         VisitSetHomeObject(value, literal, property);
 
@@ -1850,8 +1842,7 @@ void BytecodeGenerator::VisitObjectLiteral(ObjectLiteral* expr) {
       case ObjectLiteral::Property::SETTER: {
         RegisterList args = register_allocator()->NewRegisterList(4);
         builder()->MoveRegister(literal, args[0]);
-        VisitForAccumulatorValue(property->key());
-        builder()->ConvertAccumulatorToName(args[1]);
+        BuildLoadPropertyKey(property, args[1]);
         VisitForRegisterValue(property->value(), args[2]);
         VisitSetHomeObject(args[2], literal, property);
         builder()
@@ -3562,6 +3553,16 @@ void BytecodeGenerator::BuildPushUndefinedIntoRegisterList(
   builder()->LoadUndefined().StoreAccumulatorInRegister(reg);
 }
 
+void BytecodeGenerator::BuildLoadPropertyKey(LiteralProperty* property,
+                                             Register out_reg) {
+  if (property->key()->IsStringLiteral()) {
+    VisitForRegisterValue(property->key(), out_reg);
+  } else {
+    VisitForAccumulatorValue(property->key());
+    builder()->ConvertAccumulatorToName(out_reg);
+  }
+}
+
 // Visits the expression |expr| for testing its boolean value and jumping to the
 // |then| or |other| label depending on value and short-circuit semantics
 void BytecodeGenerator::VisitForTest(Expression* expr,

src/interpreter/bytecode-generator.h

@@ -163,6 +163,8 @@ class BytecodeGenerator final : public AstVisitor<BytecodeGenerator> {
 
   void BuildPushUndefinedIntoRegisterList(RegisterList* reg_list);
 
+  void BuildLoadPropertyKey(LiteralProperty* property, Register out_reg);
+
   // Visitors for obtaining expression result in the accumulator, in a
   // register, or just getting the effect. Some visitors return a TypeHint which
   // specifies the type of the result of the visited expression.

src/interpreter/bytecodes.h

@@ -618,11 +618,6 @@ class V8_EXPORT_PRIVATE Bytecodes final {
     return bytecode == Bytecode::kLdar || bytecode == Bytecode::kStar;
   }
 
-  // Returns true if |bytecode| puts a name in the accumulator.
-  static constexpr bool PutsNameInAccumulator(Bytecode bytecode) {
-    return bytecode == Bytecode::kTypeOf;
-  }
-
   // Returns true if the bytecode is a call or a constructor call.
   static constexpr bool IsCallOrConstruct(Bytecode bytecode) {
     return bytecode == Bytecode::kCall || bytecode == Bytecode::kCallProperty ||

src/interpreter/mkpeephole.cc

@@ -79,10 +79,6 @@ const char* PeepholeActionTableWriter::kNamespaceElements[] = {"v8", "internal",
 // static
 PeepholeActionAndData PeepholeActionTableWriter::LookupActionAndData(
     Bytecode last, Bytecode current) {
-  if (current == Bytecode::kToName && Bytecodes::PutsNameInAccumulator(last)) {
-    return {PeepholeAction::kChangeBytecodeAction, Bytecode::kStar};
-  }
-
   // Nop are placeholders for holding source position information and can be
   // elided if there is no source information.
   if (last == Bytecode::kNop) {

test/cctest/interpreter/bytecode_expectations/ObjectLiterals.golden

@@ -382,7 +382,7 @@ bytecodes: [
                 B(Star), R(3),
                 B(StaDataPropertyInLiteral), R(1), R(2), U8(0), U8(5),
                 B(LdaConstant), U8(3),
-                B(ToName), R(3),
+                B(Star), R(3),
                 B(CreateClosure), U8(4), U8(2), U8(2),
                 B(Star), R(4),
                 B(LdaZero),
@@ -390,7 +390,7 @@ bytecodes: [
                 B(Mov), R(1), R(2),
                 B(CallRuntime), U16(Runtime::kDefineGetterPropertyUnchecked), R(2), U8(4),
                 B(LdaConstant), U8(3),
-                B(ToName), R(3),
+                B(Star), R(3),
                 B(CreateClosure), U8(5), U8(3), U8(2),
                 B(Star), R(4),
                 B(LdaZero),

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

@@ -188,33 +188,6 @@ TEST_F(BytecodePeepholeOptimizerTest, StarRxLdarRxStatementStarRy) {
   CHECK_EQ(last_written(), third);
 }
 
-TEST_F(BytecodePeepholeOptimizerTest, LdarToName) {
-  BytecodeNode first(Bytecode::kLdar, Register(0).ToOperand());
-  BytecodeNode second(Bytecode::kToName, Register(0).ToOperand());
-  optimizer()->Write(&first);
-  CHECK_EQ(write_count(), 0);
-  optimizer()->Write(&second);
-  CHECK_EQ(write_count(), 1);
-  CHECK_EQ(last_written(), first);
-  Flush();
-  CHECK_EQ(write_count(), 2);
-  CHECK_EQ(last_written(), second);
-}
-
-TEST_F(BytecodePeepholeOptimizerTest, TypeOfToName) {
-  BytecodeNode first(Bytecode::kTypeOf);
-  BytecodeNode second(Bytecode::kToName, Register(0).ToOperand());
-  optimizer()->Write(&first);
-  CHECK_EQ(write_count(), 0);
-  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);
-}
-
 // Tests covering BytecodePeepholeOptimizer::CanElideLast().
 
 TEST_F(BytecodePeepholeOptimizerTest, LdaTrueLdaFalse) {