[wasm] Generate source position information

src/compiler/source-position.h

 // Copyright 2014 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_COMPILER_SOURCE_POSITION_H_
 #define V8_COMPILER_SOURCE_POSITION_H_
 
 #include "src/assembler.h"
 #include "src/compiler/node-aux-data.h"
 
@@ skipping 23 matching lines @@
   return lhs.raw() == rhs.raw();
 }
 
 inline bool operator!=(const SourcePosition& lhs, const SourcePosition& rhs) {
   return !(lhs == rhs);
 }
 
 
 class SourcePositionTable final {
  public:
-  class Scope final {
-   public:
-    Scope(SourcePositionTable* source_positions, SourcePosition position)
-        : source_positions_(source_positions),
-          prev_position_(source_positions->current_position_) {
-      Init(position);
-    }
-    Scope(SourcePositionTable* source_positions, Node* node)
-        : source_positions_(source_positions),
-          prev_position_(source_positions->current_position_) {
-      Init(source_positions_->GetSourcePosition(node));
-    }
-    ~Scope() { source_positions_->current_position_ = prev_position_; }
-
-   private:
-    void Init(SourcePosition position) {
-      if (position.IsKnown()) source_positions_->current_position_ = position;
-    }
-
-    SourcePositionTable* const source_positions_;
-    SourcePosition const prev_position_;
-    DISALLOW_COPY_AND_ASSIGN(Scope);
-  };
-
   explicit SourcePositionTable(Graph* graph);
   ~SourcePositionTable() {
     if (decorator_) RemoveDecorator();
   }
 
   void AddDecorator();
   void RemoveDecorator();
 
   SourcePosition GetSourcePosition(Node* node) const;
 
+#ifdef DEBUG

[titzer, 2016/04/18 11:03:51]

I'm not sure why this would only be useful in debug mode.

[Clemens Hammacher, 2016/04/18 11:18:09]

Right now it's only used in debug mode, but sure, it does not hurt to make it
always available.

+  Graph* GetGraph() const { return graph_; }
+#endif
+
   void Print(std::ostream& os) const;
 
  private:
   class Decorator;
+  friend class SourcePositionScope;
 
   Graph* const graph_;
   Decorator* decorator_;
   SourcePosition current_position_;
   NodeAuxData<SourcePosition> table_;
 
   DISALLOW_COPY_AND_ASSIGN(SourcePositionTable);
 };
 
+class SourcePositionScope final {

[titzer, 2016/04/18 11:03:51]

I think I prefer leaving this as an inner class in SourcePositionTable.

[Clemens Hammacher, 2016/04/18 11:18:09]

If we don't need to forward-reference it from compiler.h, then I will revert
this change.

+ public:
+  SourcePositionScope(SourcePositionTable* source_positions,
+                      SourcePosition position = SourcePosition::Unknown())
+      : source_positions_(source_positions),
+        prev_position_(source_positions->current_position_) {
+    Init(position);
+  }
+  SourcePositionScope(SourcePositionTable* source_positions, Node* node)
+      : source_positions_(source_positions),
+        prev_position_(source_positions->current_position_) {
+    Init(source_positions_->GetSourcePosition(node));
+  }
+  ~SourcePositionScope() {
+    source_positions_->current_position_ = prev_position_;
+  }
+
+  void SetCurrentPosition(SourcePosition position) {
+    DCHECK(position.IsKnown());
+    source_positions_->current_position_ = position;
+  }
+
+ private:
+  void Init(SourcePosition position) {
+    if (position.IsKnown()) SetCurrentPosition(position);
+  }
+
+  SourcePositionTable* const source_positions_;
+  SourcePosition const prev_position_;
+  DISALLOW_COPY_AND_ASSIGN(SourcePositionScope);
+};
+
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SOURCE_POSITION_H_