Lazily save double registers for HCallRuntime instructions within Hydrogen code stubs.

src/x64/macro-assembler-x64.h

Index: src/x64/macro-assembler-x64.h
diff --git a/src/x64/macro-assembler-x64.h b/src/x64/macro-assembler-x64.h
index 09dae3e09608b248886bd0a7b47a783a9171d25b..2c8c70b785bfbe9496cd3ebee9297a06f8ae90a5 100644
--- a/src/x64/macro-assembler-x64.h
+++ b/src/x64/macro-assembler-x64.h
@@ -1249,13 +1249,20 @@ class MacroAssembler: public Assembler {
   void StubReturn(int argc);
 
   // Call a runtime routine.
-  void CallRuntime(const Runtime::Function* f, int num_arguments);
+  void CallRuntime(const Runtime::Function* f,
+                   int num_arguments,
+                   SaveFPRegsMode save_doubles = kDontSaveFPRegs);
 
   // Call a runtime function and save the value of XMM registers.
-  void CallRuntimeSaveDoubles(Runtime::FunctionId id);
+  void CallRuntimeSaveDoubles(Runtime::FunctionId id) {
+    const Runtime::Function* function = Runtime::FunctionForId(id);
+    CallRuntime(function, function->nargs, kSaveFPRegs);
+  }
 
   // Convenience function: Same as above, but takes the fid instead.
-  void CallRuntime(Runtime::FunctionId id, int num_arguments);
+  void CallRuntime(Runtime::FunctionId id, int num_arguments) {
+    CallRuntime(Runtime::FunctionForId(id), num_arguments);
+  }
 
   // Convenience function: call an external reference.
   void CallExternalReference(const ExternalReference& ext,