VM: Move branch optimizations into a separate file.

runtime/vm/flow_graph_optimizer.h

Index: runtime/vm/flow_graph_optimizer.h
diff --git a/runtime/vm/flow_graph_optimizer.h b/runtime/vm/flow_graph_optimizer.h
index afbb455ce1a26e37819bd96f564487ae549696d3..95605784c12bc5055aebfc51210b99f1071b78fe 100644
--- a/runtime/vm/flow_graph_optimizer.h
+++ b/runtime/vm/flow_graph_optimizer.h
@@ -335,42 +335,6 @@ class DeadCodeElimination : public AllStatic {
 };
 
 
-// Rewrite branches to eliminate materialization of boolean values after
-// inlining, and to expose other optimizations (e.g., constant folding of
-// branches, unreachable code elimination).
-class BranchSimplifier : public AllStatic {
- public:
-  static void Simplify(FlowGraph* flow_graph);
-
-  // Replace a target entry instruction with a join entry instruction.  Does
-  // not update the original target's predecessors to point to the new block
-  // and does not replace the target in already computed block order lists.
-  static JoinEntryInstr* ToJoinEntry(Zone* zone,
-                                     TargetEntryInstr* target);
-
- private:
-  // Match an instance of the pattern to rewrite.  See the implementation
-  // for the patterns that are handled by this pass.
-  static bool Match(JoinEntryInstr* block);
-
-  // Duplicate a branch while replacing its comparison's left and right
-  // inputs.
-  static BranchInstr* CloneBranch(Zone* zone,
-                                  BranchInstr* branch,
-                                  Value* new_left,
-                                  Value* new_right);
-};
-
-
-// Rewrite diamond control flow patterns that materialize values to use more
-// efficient branchless code patterns if such are supported on the current
-// platform.
-class IfConverter : public AllStatic {
- public:
-  static void Simplify(FlowGraph* flow_graph);
-};
-
-
 class AllocationSinking : public ZoneAllocated {
  public:
   explicit AllocationSinking(FlowGraph* flow_graph)