Add a goto instruction to the IL use it to terminate basic blocks.

vm/intermediate_language.h

Index: vm/intermediate_language.h
===================================================================
--- vm/intermediate_language.h	(revision 9252)
+++ vm/intermediate_language.h	(working copy)
@@ -1707,6 +1707,7 @@
   M(Throw)                                                                     \
   M(ReThrow)                                                                   \
   M(Branch)                                                                    \
+  M(Goto)                                                                      \
   M(ParallelMove)
 
 
@@ -1818,12 +1819,7 @@
 
   // Returns structure describing location constraints required
   // to emit native code for this instruction.
-  virtual LocationSummary* locs() {
-    // TODO(vegorov): This should be pure virtual method.
-    // However we are temporary using NULL for instructions that
-    // were not converted to the location based code generation yet.
-    return NULL;
-  }
+  virtual LocationSummary* locs()  = 0;
 
   virtual void EmitNativeCode(FlowGraphCompiler* compiler) {
     UNIMPLEMENTED();
@@ -1890,7 +1886,7 @@
     dominated_blocks_.Add(block);
   }
 
-  Instruction* last_instruction() const { return last_instruction_; }
+  inline Instruction* last_instruction() const;
   void set_last_instruction(Instruction* instr) { last_instruction_ = instr; }
 
   virtual void DiscoverBlocks(
@@ -1901,6 +1897,8 @@
       GrowableArray<BitVector*>* assigned_vars,
       intptr_t variable_count);
 
+  virtual LocationSummary* locs()  { return NULL; }
+
  protected:
   BlockEntryInstr()
       : preorder_number_(-1),
@@ -1993,6 +1991,7 @@
     return successor_;
   }
   virtual void SetSuccessor(Instruction* instr) {
+    ASSERT(instr == NULL || !instr->IsBlockEntry());
     successor_ = instr;
   }
 
@@ -2047,6 +2046,7 @@
     return successor_;
   }
   virtual void SetSuccessor(Instruction* instr) {
+    ASSERT(instr == NULL || !instr->IsBlockEntry());
     successor_ = instr;
   }
 
@@ -2088,6 +2088,7 @@
   }
 
   virtual void SetSuccessor(Instruction* instr) {
+    ASSERT(instr == NULL || !instr->IsBlockEntry());
     successor_ = instr;
   }
 
@@ -2149,6 +2150,7 @@
   }
 
   virtual void SetSuccessor(Instruction* instr) {
+    ASSERT(instr == NULL || !instr->IsBlockEntry());
     successor_ = instr;
   }
 
@@ -2186,6 +2188,8 @@
   virtual Instruction* StraightLineSuccessor() const { return NULL; }
   virtual void SetSuccessor(Instruction* instr) { UNREACHABLE(); }
 
+  virtual LocationSummary* locs()  { return NULL; }
+
  private:
   GrowableArray<Value*> inputs_;
 
@@ -2366,6 +2370,27 @@
 };
 
 
+class GotoInstr : public Instruction {
+ public:
+  explicit GotoInstr(BlockEntryInstr* successor)
+      : successor_(successor) {
+        ASSERT(successor != NULL);
+      }
+
+  DECLARE_INSTRUCTION(Goto)
+
+  virtual Instruction* StraightLineSuccessor() const { return successor_; }
+  virtual void SetSuccessor(Instruction* instr) {
+    successor_ = instr->AsBlockEntry();
+  }
+
+  virtual LocationSummary* locs() { return NULL; }
+
+ private:
+  BlockEntryInstr* successor_;
+};
+
+
 class MoveOperands : public ValueObject {
  public:
   MoveOperands(Location dest, Location src) : dest_(dest), src_(src) { }
@@ -2400,6 +2425,17 @@
 #undef DECLARE_INSTRUCTION
 
 
+// Definition of inline functions.
+Instruction* BlockEntryInstr::last_instruction() const {
+  ASSERT(last_instruction_->IsGraphEntry() ||
+         last_instruction_->IsGoto() ||
+         last_instruction_->IsReturn() ||
+         last_instruction_->IsBranch() ||
+         last_instruction_->IsThrow() ||
+         last_instruction_->IsReThrow());
+  return last_instruction_;
+}
+
 // Visitor base class to visit each instruction and computation in a flow
 // graph as defined by a reversed list of basic blocks.
 class FlowGraphVisitor : public ValueObject {