Removed loop depth info tracking at graph build time.

runtime/vm/intermediate_language.h

Index: runtime/vm/intermediate_language.h
===================================================================
--- runtime/vm/intermediate_language.h	(revision 17406)
+++ runtime/vm/intermediate_language.h	(working copy)
@@ -656,8 +656,6 @@
 // branches.
 class BlockEntryInstr : public Instruction {
  public:
-  static const intptr_t kInvalidLoopDepth = -1;
-
   virtual BlockEntryInstr* AsBlockEntry() { return this; }
 
   virtual intptr_t PredecessorCount() const = 0;
@@ -751,19 +749,12 @@
     loop_info_ = loop_info;
   }
 
-  intptr_t loop_depth() const { return loop_depth_; }
-  void set_loop_depth(intptr_t loop_depth) {
-    ASSERT(loop_depth_ == kInvalidLoopDepth);
-    ASSERT(loop_depth != kInvalidLoopDepth);
-    loop_depth_ = loop_depth;
-  }
-
   virtual BlockEntryInstr* GetBlock() const {
     return const_cast<BlockEntryInstr*>(this);
   }
 
  protected:
-  BlockEntryInstr(intptr_t block_id, intptr_t try_index, intptr_t loop_depth)
+  BlockEntryInstr(intptr_t block_id, intptr_t try_index)
       : block_id_(block_id),
         try_index_(try_index),
         preorder_number_(-1),
@@ -772,8 +763,7 @@
         dominated_blocks_(1),
         last_instruction_(NULL),
         parallel_move_(NULL),
-        loop_info_(NULL),
-        loop_depth_(loop_depth) { }
+        loop_info_(NULL) { }
 
  private:
   virtual void ClearPredecessors() = 0;
@@ -800,9 +790,6 @@
   // preorder number.
   BitVector* loop_info_;
 
-  // Syntactic loop depth of the block.
-  intptr_t loop_depth_;
-
   DISALLOW_COPY_AND_ASSIGN(BlockEntryInstr);
 };
 
@@ -906,8 +893,8 @@
 
 class JoinEntryInstr : public BlockEntryInstr {
  public:
-  JoinEntryInstr(intptr_t block_id, intptr_t try_index, intptr_t loop_depth)
-      : BlockEntryInstr(block_id, try_index, loop_depth),
+  JoinEntryInstr(intptr_t block_id, intptr_t try_index)
+      : BlockEntryInstr(block_id, try_index),
         predecessors_(2),  // Two is the assumed to be the common case.
         phis_(NULL),
         phi_count_(0) { }
@@ -978,8 +965,8 @@
 
 class TargetEntryInstr : public BlockEntryInstr {
  public:
-  TargetEntryInstr(intptr_t block_id, intptr_t try_index, intptr_t loop_depth)
-      : BlockEntryInstr(block_id, try_index, loop_depth),
+  TargetEntryInstr(intptr_t block_id, intptr_t try_index)
+      : BlockEntryInstr(block_id, try_index),
         predecessor_(NULL),
         catch_try_index_(CatchClauseNode::kInvalidTryIndex),
         catch_handler_types_(Array::ZoneHandle()) { }