Generate some intrinsics using our IR.

runtime/vm/flow_graph_compiler.h

Index: runtime/vm/flow_graph_compiler.h
===================================================================
--- runtime/vm/flow_graph_compiler.h	(revision 39726)
+++ runtime/vm/flow_graph_compiler.h	(working copy)
@@ -61,7 +61,7 @@
 
   bool IsScratchLocation(Location loc);
   intptr_t AllocateScratchRegister(Location::Kind kind,
-                                   intptr_t blocked,
+                                   uword blocked_mask,
                                    intptr_t first_free_register,
                                    intptr_t last_free_register,
                                    bool* spilled);
@@ -96,8 +96,11 @@
   void StoreObject(const Address& dst, const Object& obj);
   void Exchange(Register reg, const Address& mem);
   void Exchange(const Address& mem1, const Address& mem2);
-  void Exchange(Register reg, intptr_t stack_offset);
-  void Exchange(intptr_t stack_offset1, intptr_t stack_offset2);
+  void Exchange(Register reg, Register base_reg, intptr_t stack_offset);
+  void Exchange(Register base_reg1,
+                intptr_t stack_offset1,
+                Register base_reg2,
+                intptr_t stack_offset2);
 
   FlowGraphCompiler* compiler_;
 
@@ -289,6 +292,10 @@
   bool CanOSRFunction() const;
   bool is_optimizing() const { return is_optimizing_; }
 
+  void EnterIntrinsicMode();
+  void ExitIntrinsicMode();
+  bool intrinsic_mode() const { return intrinsic_mode_; }
+
   bool ForceSlowPathForStackOverflow() const;
 
   const GrowableArray<BlockInfo*>& block_info() const { return block_info_; }
@@ -617,6 +624,9 @@
   const bool is_optimizing_;
   // Set to true if optimized code has IC calls.
   bool may_reoptimize_;
+  // True while emitting intrinsic code.
+  bool intrinsic_mode_;
+  Label intrinsic_deopt_label_;
 
   const Class& double_class_;
   const Class& mint_class_;