[Interpreter] Add for/while/do support to the bytecode generator.

src/interpreter/control-flow-builders.h

+// 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.
+
+#ifndef V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_
+#define V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_
+
+#include "src/interpreter/bytecode-array-builder.h"
+
+#include "src/zone-containers.h"
+
+namespace v8 {
+namespace internal {
+namespace interpreter {
+
+class ControlFlowBuilder BASE_EMBEDDED {
+ public:
+  explicit ControlFlowBuilder(BytecodeArrayBuilder* builder)
+      : builder_(builder) {}
+  virtual ~ControlFlowBuilder() {}
+
+ protected:
+  BytecodeArrayBuilder* builder() const { return builder_; }
+
+ private:
+  BytecodeArrayBuilder* builder_;
+
+  DISALLOW_COPY_AND_ASSIGN(ControlFlowBuilder);
+};
+
+
+class LoopBuilder : public ControlFlowBuilder {
+ public:
+  explicit LoopBuilder(BytecodeArrayBuilder* builder)
+      : ControlFlowBuilder(builder),
+        continue_labels_(builder->zone()),
+        break_labels_(builder->zone()) {}
+  ~LoopBuilder();
+
+  BytecodeLabel* continue_label() { return &continue_label_; }

[rmcilroy, 2015/10/01 09:18:56]

As discussed offline, instead of this could we have a BindContinue operation on
the LoopBuilder and just stash the bind point, then do the binding of the
continue labels in a for loop (which should avoid the need for the the new
Bind(BytecodeLabel* unbound, BytecodeLabel* bound) (instead just needing one
which passes in the explicit offset).

[oth, 2015/10/01 11:43:02]

The code is re-worked to partially accommodate this comment and Michi's comment
on naming and clarity.

In new regime, there's no continue_label()/break_label() nor code in the
destructor. Instead, there's methods that called SetContinueTarget and
SetBreakTarget that are called after the loop construction is done. These take a
label set during loop construction and update all the referring sites.
 
Bind(unbound_label, bound_label) is updated such that the bound argument is
pointer to a const to make things clearer.

PTAL.

[Michael Starzinger, 2015/10/01 11:49:36]

Acknowledged. Works for me, it's clearer now.

+  BytecodeLabel* break_label() { return &break_label_; }
+
+  void Break();
+  void Continue();
+
+ private:
+  void BindLabels(BytecodeLabel* target, ZoneVector<BytecodeLabel>* labels);
+
+  BytecodeLabel continue_label_;
+  BytecodeLabel break_label_;
+
+  ZoneVector<BytecodeLabel> continue_labels_;

[Michael Starzinger, 2015/10/01 08:55:24]

nit: The naming overlap is a little bit confusing I think. Would renaming the
vector to "break_sites" and the label above to "break_target" help? Also
comments could help.

[oth, 2015/10/01 11:43:02]

Done.

+  ZoneVector<BytecodeLabel> break_labels_;
+};
+
+}  // namespace interpreter
+}  // namespace internal
+}  // namespace v8
+
+#endif  // V8_INTERPRETER_CONTROL_FLOW_BUILDERS_H_