[turbofan] Treat uninitialized source positions as unknown.

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"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Encapsulates encoding and decoding of sources positions from which Nodes
 // originated.
 class SourcePosition final {
  public:
   explicit SourcePosition(int raw = kUnknownPosition) : raw_(raw) {}
 
   static SourcePosition Unknown() { return SourcePosition(kUnknownPosition); }
   bool IsUnknown() const { return raw() == kUnknownPosition; }
-
-  static SourcePosition Invalid() { return SourcePosition(kInvalidPosition); }
-  bool IsInvalid() const { return raw() == kInvalidPosition; }
+  bool IsKnown() const { return raw() != kUnknownPosition; }
 
   int raw() const { return raw_; }
 
  private:
-  static const int kInvalidPosition = -2;
   static const int kUnknownPosition = RelocInfo::kNoPosition;
-  STATIC_ASSERT(kInvalidPosition != kUnknownPosition);
   int raw_;
 };
 
 
 inline bool operator==(const SourcePosition& lhs, const SourcePosition& rhs) {
   return lhs.raw() == rhs.raw();
 }
 
 inline bool operator!=(const SourcePosition& lhs, const SourcePosition& rhs) {
   return !(lhs == rhs);
@@ skipping 11 matching lines @@
     }
     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.IsUnknown() || prev_position_.IsInvalid()) {
-        source_positions_->current_position_ = 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();
@@ skipping 15 matching lines @@
   NodeAuxData<SourcePosition> table_;
 
   DISALLOW_COPY_AND_ASSIGN(SourcePositionTable);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_SOURCE_POSITION_H_