Generate some intrinsics using our IR.

runtime/vm/assembler_mips.h

Index: runtime/vm/assembler_mips.h
===================================================================
--- runtime/vm/assembler_mips.h	(revision 39909)
+++ runtime/vm/assembler_mips.h	(working copy)
@@ -144,7 +144,8 @@
         use_far_branches_(use_far_branches),
         delay_slot_available_(false),
         in_delay_slot_(false),
-        comments_() { }
+        comments_(),
+        allow_constant_pool_(true) { }
   ~Assembler() { }
 
   void PopRegister(Register r) { Pop(r); }
@@ -1251,6 +1252,13 @@
   static bool IsSafe(const Object& object) { return true; }
   static bool IsSafeSmi(const Object& object) { return object.IsSmi(); }
 
+  bool allow_constant_pool() const {
+    return allow_constant_pool_;
+  }
+  void set_allow_constant_pool(bool b) {
+    allow_constant_pool_ = b;
+  }
+
  private:
   AssemblerBuffer buffer_;
   GrowableObjectArray& object_pool_;  // Objects and patchable jump targets.
@@ -1280,6 +1288,8 @@
 
   GrowableArray<CodeComment*> comments_;
 
+  bool allow_constant_pool_;
+
   void Emit(int32_t value) {
     // Emitting an instruction clears the delay slot state.
     in_delay_slot_ = false;