[kernel] Debugging of switch statement

runtime/vm/kernel_binary.cc

Index: runtime/vm/kernel_binary.cc
diff --git a/runtime/vm/kernel_binary.cc b/runtime/vm/kernel_binary.cc
index a7f85598be4769c585137f54119ff12d14d70789..ff5c3d6eb6ee64f8a40e9e8d46b84fcb9b43d544 100644
--- a/runtime/vm/kernel_binary.cc
+++ b/runtime/vm/kernel_binary.cc
@@ -1595,6 +1595,13 @@ SwitchStatement* SwitchStatement::ReadFrom(Reader* reader) {
 SwitchCase* SwitchCase::ReadFrom(Reader* reader) {
   TRACE_READ_OFFSET();
   expressions_.ReadFromStatic<Expression>(reader);
+  // List of expression offsets of same length as expressions_: This serves as

[Kevin Millikin (Google), 2017/03/20 12:29:47]

I think it's obvious that it serves as the positions of the expression.  And
it's equally useful in all cases.  Don't editorialize too much in comments.

If you think it's confusing and needs a remark, you could say that we wouldn't
need this if all constant expressions had a position.

[jensj, 2017/03/21 10:06:19]

Comment removed.

+  // positions of the expressions, especially useful if the expressions
+  // doesn't have a position (e.g. int literal).
+  int length = reader->ReadListLength();
+  for (intptr_t i = 0; i < length; ++i) {
+    expressions_[i]->set_position(reader->ReadPosition());
+  }
   is_default_ = reader->ReadBool();
   body_ = Statement::ReadFrom(reader);
   return this;