Decouple SourcePositionTableBuilder from Zone

Currently the SourcePositionTableBuilder requires a Zone because it
holds a ZoneVector<byte> of the encoded entries. Since ZoneVector is a
suboptimal data structure anyway, and for Liftoff we don't even have a
Zone allocated currently, this CL replaces the ZoneVector by
std::vector.

R=mstarzinger@chromium.org

Bug: v8:6600
Change-Id: I8010143e917e2351664e2b53746753b597f4407a
Reviewed-on: https://chromium-review.googlesource.com/779181Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49534}

src/compiler/code-generator.cc

@@ -69,8 +69,7 @@ CodeGenerator::CodeGenerator(
       osr_helper_(osr_helper),
       osr_pc_offset_(-1),
       optimized_out_literal_id_(-1),
-      source_position_table_builder_(zone(),
-                                     info->SourcePositionRecordingMode()),
+      source_position_table_builder_(info->SourcePositionRecordingMode()),
       protected_instructions_(protected_instructions),
       result_(kSuccess) {
   for (int i = 0; i < code->InstructionBlockCount(); ++i) {

src/debug/liveedit.cc

@@ -948,8 +948,7 @@ static int TranslatePosition(int original_position,
 void TranslateSourcePositionTable(Handle<BytecodeArray> code,
                                   Handle<JSArray> position_change_array) {
   Isolate* isolate = code->GetIsolate();
-  Zone zone(isolate->allocator(), ZONE_NAME);
-  SourcePositionTableBuilder builder(&zone);
+  SourcePositionTableBuilder builder;
 
   Handle<ByteArray> source_position_table(code->SourcePositionTable());
   for (SourcePositionTableIterator iterator(*source_position_table);

src/interpreter/bytecode-array-builder.h

@@ -31,8 +31,7 @@ class BytecodeRegisterOptimizer;
 class BytecodeJumpTable;
 class Register;
 
-class V8_EXPORT_PRIVATE BytecodeArrayBuilder final
-    : public NON_EXPORTED_BASE(ZoneObject) {
+class V8_EXPORT_PRIVATE BytecodeArrayBuilder final {
  public:
   BytecodeArrayBuilder(
       Zone* zone, int parameter_count, int locals_count,

src/interpreter/bytecode-array-writer.cc

@@ -26,7 +26,7 @@ BytecodeArrayWriter::BytecodeArrayWriter(
     SourcePositionTableBuilder::RecordingMode source_position_mode)
     : bytecodes_(zone),
       unbound_jumps_(0),
-      source_position_table_builder_(zone, source_position_mode),
+      source_position_table_builder_(source_position_mode),
       constant_array_builder_(constant_array_builder),
       last_bytecode_(Bytecode::kIllegal),
       last_bytecode_offset_(0),

src/interpreter/bytecode-generator.cc

@@ -812,10 +812,9 @@ class BytecodeGenerator::FeedbackSlotCache : public ZoneObject {
 BytecodeGenerator::BytecodeGenerator(
     CompilationInfo* info, const AstStringConstants* ast_string_constants)
     : zone_(info->zone()),
-      builder_(new (zone()) BytecodeArrayBuilder(
-          zone(), info->num_parameters_including_this(),
-          info->scope()->num_stack_slots(), info->feedback_vector_spec(),
-          info->SourcePositionRecordingMode())),
+      builder_(zone(), info->num_parameters_including_this(),
+               info->scope()->num_stack_slots(), info->feedback_vector_spec(),
+               info->SourcePositionRecordingMode()),
       info_(info),
       ast_string_constants_(ast_string_constants),
       closure_scope_(info->scope()),

src/interpreter/bytecode-generator.h

@@ -242,7 +242,7 @@ class BytecodeGenerator final : public AstVisitor<BytecodeGenerator> {
 
   inline Register generator_object() const;
 
-  inline BytecodeArrayBuilder* builder() const { return builder_; }
+  inline BytecodeArrayBuilder* builder() { return &builder_; }
   inline Zone* zone() const { return zone_; }
   inline DeclarationScope* closure_scope() const { return closure_scope_; }
   inline CompilationInfo* info() const { return info_; }
@@ -265,7 +265,7 @@ class BytecodeGenerator final : public AstVisitor<BytecodeGenerator> {
     execution_result_ = execution_result;
   }
   ExpressionResultScope* execution_result() const { return execution_result_; }
-  BytecodeRegisterAllocator* register_allocator() const {
+  BytecodeRegisterAllocator* register_allocator() {
     return builder()->register_allocator();
   }
 
@@ -290,7 +290,7 @@ class BytecodeGenerator final : public AstVisitor<BytecodeGenerator> {
   }
 
   Zone* zone_;
-  BytecodeArrayBuilder* builder_;
+  BytecodeArrayBuilder builder_;
   CompilationInfo* info_;
   const AstStringConstants* ast_string_constants_;
   DeclarationScope* closure_scope_;

src/source-position-table.cc

@@ -47,7 +47,7 @@ void SubtractFromEntry(PositionTableEntry& value,
 
 // Helper: Encode an integer.
 template <typename T>
-void EncodeInt(ZoneVector<byte>& bytes, T value) {
+void EncodeInt(std::vector<byte>& bytes, T value) {
   // Zig-zag encoding.
   static const int kShift = sizeof(T) * kBitsPerByte - 1;
   value = ((value << 1) ^ (value >> kShift));
@@ -64,7 +64,7 @@ void EncodeInt(ZoneVector<byte>& bytes, T value) {
 }
 
 // Encode a PositionTableEntry.
-void EncodeEntry(ZoneVector<byte>& bytes, const PositionTableEntry& entry) {
+void EncodeEntry(std::vector<byte>& bytes, const PositionTableEntry& entry) {
   // We only accept ascending code offsets.
   DCHECK_GE(entry.code_offset, 0);
   // Since code_offset is not negative, we use sign to encode is_statement.
@@ -108,14 +108,8 @@ void DecodeEntry(ByteArray* bytes, int* index, PositionTableEntry* entry) {
 }  // namespace
 
 SourcePositionTableBuilder::SourcePositionTableBuilder(
-    Zone* zone, SourcePositionTableBuilder::RecordingMode mode)
-    : mode_(mode),
-      bytes_(zone),
-#ifdef ENABLE_SLOW_DCHECKS
-      raw_entries_(zone),
-#endif
-      previous_() {
-}
+    SourcePositionTableBuilder::RecordingMode mode)
+    : mode_(mode), previous_() {}
 
 void SourcePositionTableBuilder::AddPosition(size_t code_offset,
                                              SourcePosition source_position,

src/source-position-table.h

@@ -35,8 +35,8 @@ class V8_EXPORT_PRIVATE SourcePositionTableBuilder {
  public:
   enum RecordingMode { OMIT_SOURCE_POSITIONS, RECORD_SOURCE_POSITIONS };
 
-  SourcePositionTableBuilder(Zone* zone,
-                             RecordingMode mode = RECORD_SOURCE_POSITIONS);
+  explicit SourcePositionTableBuilder(
+      RecordingMode mode = RECORD_SOURCE_POSITIONS);
 
   void AddPosition(size_t code_offset, SourcePosition source_position,
                    bool is_statement);
@@ -49,9 +49,9 @@ class V8_EXPORT_PRIVATE SourcePositionTableBuilder {
   inline bool Omit() const { return mode_ == OMIT_SOURCE_POSITIONS; }
 
   RecordingMode mode_;
-  ZoneVector<byte> bytes_;
+  std::vector<byte> bytes_;
 #ifdef ENABLE_SLOW_DCHECKS
-  ZoneVector<PositionTableEntry> raw_entries_;
+  std::vector<PositionTableEntry> raw_entries_;
 #endif
   PositionTableEntry previous_;  // Previously written entry, to compute delta.
 };

test/unittests/source-position-table-unittest.cc

@@ -12,7 +12,7 @@ namespace v8 {
 namespace internal {
 namespace interpreter {
 
-class SourcePositionTableTest : public TestWithIsolateAndZone {
+class SourcePositionTableTest : public TestWithIsolate {
  public:
   SourcePositionTableTest() {}
   ~SourcePositionTableTest() override {}
@@ -28,7 +28,7 @@ static int offsets[] = {0,   1,   2,    3,    4,     30,      31,  32,
                         129, 250, 1000, 9999, 12000, 31415926};
 
 TEST_F(SourcePositionTableTest, EncodeStatement) {
-  SourcePositionTableBuilder builder(zone());
+  SourcePositionTableBuilder builder;
   for (size_t i = 0; i < arraysize(offsets); i++) {
     builder.AddPosition(offsets[i], toPos(offsets[i]), true);
   }
@@ -39,7 +39,7 @@ TEST_F(SourcePositionTableTest, EncodeStatement) {
 }
 
 TEST_F(SourcePositionTableTest, EncodeStatementDuplicates) {
-  SourcePositionTableBuilder builder(zone());
+  SourcePositionTableBuilder builder;
   for (size_t i = 0; i < arraysize(offsets); i++) {
     builder.AddPosition(offsets[i], toPos(offsets[i]), true);
     builder.AddPosition(offsets[i], toPos(offsets[i] + 1), true);
@@ -51,7 +51,7 @@ TEST_F(SourcePositionTableTest, EncodeStatementDuplicates) {
 }
 
 TEST_F(SourcePositionTableTest, EncodeExpression) {
-  SourcePositionTableBuilder builder(zone());
+  SourcePositionTableBuilder builder;
   for (size_t i = 0; i < arraysize(offsets); i++) {
     builder.AddPosition(offsets[i], toPos(offsets[i]), false);
   }
@@ -59,7 +59,7 @@ TEST_F(SourcePositionTableTest, EncodeExpression) {
 }
 
 TEST_F(SourcePositionTableTest, EncodeAscending) {
-  SourcePositionTableBuilder builder(zone());
+  SourcePositionTableBuilder builder;
 
   int code_offset = 0;
   int source_position = 0;