Initial steps into streaming the kernel flowgraph

runtime/vm/kernel_binary_flowgraph.cc

+// Copyright (c) 2016, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+#include "vm/kernel_binary_flowgraph.h"
+
+#if !defined(DART_PRECOMPILED_RUNTIME)
+
+namespace dart {
+namespace kernel {
+
+Fragment KernelFlowgraphBuilder::BuildAt(int64_t kernel_offset) {
+  reader_->set_offset(kernel_offset);
+
+  uint8_t payload = 0;
+  Tag tag = reader_->ReadTag(&payload);
+  switch (tag) {
+    //    case kInvalidExpression:
+    //      return InvalidExpression::ReadFrom(reader_);
+    //    case kVariableGet:
+    //      return VariableGet::ReadFrom(reader_);
+    //    case kSpecializedVariableGet:
+    //      return VariableGet::ReadFrom(reader_, payload);
+    //    case kVariableSet:
+    //      return VariableSet::ReadFrom(reader_);
+    //    case kSpecializedVariableSet:
+    //      return VariableSet::ReadFrom(reader_, payload);
+    //    case kPropertyGet:
+    //      return PropertyGet::ReadFrom(reader_);
+    //    case kPropertySet:
+    //      return PropertySet::ReadFrom(reader_);
+    //    case kDirectPropertyGet:
+    //      return DirectPropertyGet::ReadFrom(reader_);
+    //    case kDirectPropertySet:
+    //      return DirectPropertySet::ReadFrom(reader_);
+    //    case kStaticGet:
+    //      return StaticGet::ReadFrom(reader_);
+    //    case kStaticSet:
+    //      return StaticSet::ReadFrom(reader_);
+    //    case kMethodInvocation:
+    //      return MethodInvocation::ReadFrom(reader_);
+    //    case kDirectMethodInvocation:
+    //      return DirectMethodInvocation::ReadFrom(reader_);
+    //    case kStaticInvocation:
+    //      return StaticInvocation::ReadFrom(reader_, false);
+    //    case kConstStaticInvocation:
+    //      return StaticInvocation::ReadFrom(reader_, true);
+    //    case kConstructorInvocation:
+    //      return ConstructorInvocation::ReadFrom(reader_, false);
+    //    case kConstConstructorInvocation:
+    //      return ConstructorInvocation::ReadFrom(reader_, true);
+    //    case kNot:
+    //      return Not::ReadFrom(reader_);
+    //    case kLogicalExpression:
+    //      return LogicalExpression::ReadFrom(reader_);
+    //    case kConditionalExpression:
+    //      return ConditionalExpression::ReadFrom(reader_);
+    //    case kStringConcatenation:
+    //      return StringConcatenation::ReadFrom(reader_);
+    //    case kIsExpression:
+    //      return IsExpression::ReadFrom(reader_);
+    //    case kAsExpression:
+    //      return AsExpression::ReadFrom(reader_);
+    //    case kSymbolLiteral:
+    //      return SymbolLiteral::ReadFrom(reader_);
+    //    case kTypeLiteral:
+    //      return TypeLiteral::ReadFrom(reader_);
+    //    case kThisExpression:
+    //      return ThisExpression::ReadFrom(reader_);
+    case kRethrow:
+      return buildRethrow();
+    //    case kThrow:
+    //      return Throw::ReadFrom(reader_);
+    //    case kListLiteral:
+    //      return ListLiteral::ReadFrom(reader_, false);
+    //    case kConstListLiteral:
+    //      return ListLiteral::ReadFrom(reader_, true);
+    //    case kMapLiteral:
+    //      return MapLiteral::ReadFrom(reader_, false);
+    //    case kConstMapLiteral:
+    //      return MapLiteral::ReadFrom(reader_, true);
+    //    case kAwaitExpression:
+    //      return AwaitExpression::ReadFrom(reader_);
+    //    case kFunctionExpression:
+    //      return FunctionExpression::ReadFrom(reader_);
+    //    case kLet:
+    //      return Let::ReadFrom(reader_);
+    //    case kBigIntLiteral:
+    //      return BigintLiteral::ReadFrom(reader_);
+    //    case kStringLiteral:
+    //      return StringLiteral::ReadFrom(reader_);
+    //    case kSpecialIntLiteral:
+    //      return IntLiteral::ReadFrom(reader_, payload);
+    //    case kNegativeIntLiteral:
+    //      return IntLiteral::ReadFrom(reader_, true);
+    //    case kPositiveIntLiteral:
+    //      return IntLiteral::ReadFrom(reader_, false);
+    //    case kDoubleLiteral:
+    //      return DoubleLiteral::ReadFrom(reader_);
+    //    case kTrueLiteral:
+    //      return BoolLiteral::ReadFrom(reader_, true);
+    //    case kFalseLiteral:
+    //      return BoolLiteral::ReadFrom(reader_, false);
+    //    case kNullLiteral:
+    //      return NullLiteral::ReadFrom(reader_);
+    default:
+      UNREACHABLE();
+  }
+
+  Fragment instructions;

[Kevin Millikin (Google), 2017/03/28 12:50:00]

return Fragment();

[jensj, 2017/03/29 09:30:42]

Done.

+  return instructions;
+}
+
+Fragment KernelFlowgraphBuilder::buildRethrow() {
+  Fragment instructions;
+
+  TokenPosition position = reader_->ReadPosition();

[Kevin Millikin (Google), 2017/03/28 12:50:00]

I would take all these functions (KernelReader::ReadPosition,
FlowGraphBuilder::DebugStepCheck, FlowGraphBuilder::catch_block, etc.) and make
implementations of them in KernelFlowGraphBuilder that just delegate to the
underlying implementation.

Eventually, those other classes will be able to be rolled into this one, so we
might as well start coding that way now.  Plus, it reads a lot better.

[jensj, 2017/03/29 09:30:41]

Done.

+  instructions = flowGraph_builder_->DebugStepCheck(position);

[Kevin Millikin (Google), 2017/03/28 12:50:00]

Fragment instructions = DebugStepCheck(position);

(No reason to initialize an empty fragment only to overwrite it with this one.)

[jensj, 2017/03/29 09:30:41]

Done.

+  instructions += flowGraph_builder_->LoadLocal(
+      flowGraph_builder_->catch_block_->exception_var());
+  instructions += flowGraph_builder_->PushArgument();
+  instructions += flowGraph_builder_->LoadLocal(
+      flowGraph_builder_->catch_block_->stack_trace_var());
+  instructions += flowGraph_builder_->PushArgument();
+  instructions += flowGraph_builder_->RethrowException(
+      position, flowGraph_builder_->catch_block_->catch_try_index());
+
+  return instructions;
+}
+
+}  // namespace kernel
+}  // namespace dart
+
+#endif  // !defined(DART_PRECOMPILED_RUNTIME)