Generate some intrinsics using our IR.

runtime/vm/intermediate_language_x64.cc

Index: runtime/vm/intermediate_language_x64.cc
===================================================================
--- runtime/vm/intermediate_language_x64.cc	(revision 39909)
+++ runtime/vm/intermediate_language_x64.cc	(working copy)
@@ -83,6 +83,13 @@
 void ReturnInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   Register result = locs()->in(0).reg();
   ASSERT(result == RAX);
+
+  if (compiler->intrinsic_mode()) {
+    // Intrinsics don't have a frame.
+    __ ret();
+    return;
+  }
+
 #if defined(DEBUG)
   __ Comment("Stack Check");
   Label done;
@@ -1508,10 +1515,12 @@
  public:
   BoxAllocationSlowPath(Instruction* instruction,
                         const Class& cls,
-                        Register result)
+                        Register result,
+                        bool is_intrinsic)
       : instruction_(instruction),
         cls_(cls),
-        result_(result) { }
+        result_(result),
+        is_intrinsic_(is_intrinsic) { }
 
   virtual void EmitNativeCode(FlowGraphCompiler* compiler) {
     Isolate* isolate = compiler->isolate();
@@ -1524,6 +1533,10 @@
     }
     __ Bind(entry_label());
 
+    if (is_intrinsic_) {
+      __ EnterStubFrame(true);
+    }
+
     const Code& stub =
         Code::Handle(isolate, stub_code->GetAllocationStubForClass(cls_));
     const ExternalLabel label(stub.EntryPoint());
@@ -1539,6 +1552,9 @@
                            locs);
     __ MoveRegister(result_, RAX);
     compiler->RestoreLiveRegisters(locs);
+    if (is_intrinsic_) {
+      __ LeaveStubFrame();
+    }
     __ jmp(exit_label());
   }
 
@@ -1547,7 +1563,8 @@
                        const Class& cls,
                        Register result) {
     BoxAllocationSlowPath* slow_path =
-        new BoxAllocationSlowPath(instruction, cls, result);
+        new BoxAllocationSlowPath(instruction, cls, result,
+                                  compiler->intrinsic_mode());
     compiler->AddSlowPathCode(slow_path);
 
     __ TryAllocate(cls,
@@ -1562,6 +1579,7 @@
   Instruction* instruction_;
   const Class& cls_;
   Register result_;
+  bool is_intrinsic_;
 };