[turbofan] Treat uninitialized source positions as unknown.

src/compiler/graph-visualizer.cc

 // Copyright 2013 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.
 
 #include "src/compiler/graph-visualizer.h"
 
 #include <sstream>
 #include <string>
 
 #include "src/code-stubs.h"
@@ skipping 104 matching lines @@
           << "]";
     } else if (opcode == IrOpcode::kIfTrue || opcode == IrOpcode::kIfFalse ||
                opcode == IrOpcode::kLoop) {
       os_ << ",\"rankInputs\":[" << NodeProperties::FirstControlIndex(node)
           << "]";
     }
     if (opcode == IrOpcode::kBranch) {
       os_ << ",\"rankInputs\":[0]";
     }
     SourcePosition position = positions_->GetSourcePosition(node);
-    if (!position.IsUnknown()) {
-      DCHECK(!position.IsInvalid());
+    if (position.IsKnown()) {
       os_ << ",\"pos\":" << position.raw();
     }
     os_ << ",\"opcode\":\"" << IrOpcode::Mnemonic(node->opcode()) << "\"";
     os_ << ",\"control\":" << (NodeProperties::IsControl(node) ? "true"
                                                                : "false");
     if (NodeProperties::IsTyped(node)) {
       Bounds bounds = NodeProperties::GetBounds(node);
       std::ostringstream upper;
       bounds.upper->PrintTo(upper);
       std::ostringstream lower;
@@ skipping 506 matching lines @@
         int uses = node->UseCount();
         PrintIndent();
         os_ << "0 " << uses << " ";
         PrintNode(node);
         if (FLAG_trace_turbo_types) {
           os_ << " ";
           PrintType(node);
         }
         if (positions != NULL) {
           SourcePosition position = positions->GetSourcePosition(node);
-          if (!position.IsUnknown()) {
-            DCHECK(!position.IsInvalid());
+          if (position.IsKnown()) {
             os_ << " pos:" << position.raw();
           }
         }
         os_ << " <|@\n";
       }
 
       BasicBlock::Control control = current->control();
       if (control != BasicBlock::kNone) {
         PrintIndent();
         os_ << "0 0 ";
@@ skipping 159 matching lines @@
         os << "#" << SafeId(i) << ":" << SafeMnemonic(i);
       }
       os << ")" << std::endl;
     }
   }
   return os;
 }
 }
 }
 }  // namespace v8::internal::compiler