Add tool to visualize machine code/lithium.

src/hydrogen-instructions.cc

Index: src/hydrogen-instructions.cc
diff --git a/src/hydrogen-instructions.cc b/src/hydrogen-instructions.cc
index 867fa50fca25aa30e5508edc5368d76b23c7a576..1613127e2febe7c80d0d99ceb9f4efac5bb821d8 100644
--- a/src/hydrogen-instructions.cc
+++ b/src/hydrogen-instructions.cc
@@ -741,6 +741,10 @@ void HInstruction::InsertBefore(HInstruction* next) {
   next_ = next;
   previous_ = prev;
   SetBlock(next->block());
+  if (position() == RelocInfo::kNoPosition &&
+      next->position() != RelocInfo::kNoPosition) {
+    set_position(next->position());
+  }
 }
 
 
@@ -775,6 +779,10 @@ void HInstruction::InsertAfter(HInstruction* previous) {
   if (block->last() == previous) {
     block->set_last(this);
   }
+  if (position() == RelocInfo::kNoPosition &&
+      previous->position() != RelocInfo::kNoPosition) {
+    set_position(previous->position());
+  }
 }
 
 
@@ -1592,6 +1600,11 @@ Range* HConstant::InferRange(Zone* zone) {
 }
 
 
+int HPhi::position() const {
+  return block()->first()->position();
+}
+
+
 Range* HPhi::InferRange(Zone* zone) {
   Representation r = representation();
   if (r.IsSmiOrInteger32()) {