Rework leaf calls as just simple C calls with a signature and not the NativeArgumentDescriptor.

vm/stub_code_x64.cc

Index: vm/stub_code_x64.cc
===================================================================
--- vm/stub_code_x64.cc	(revision 8859)
+++ vm/stub_code_x64.cc	(working copy)
@@ -90,49 +90,6 @@
 }
 
 
-// Input parameters:
-//   RSP : points to return address.
-//   RSP + 8 : address of last argument in argument array.
-//   RSP + 8*R10 : address of first argument in argument array.
-//   RSP + 8*R10 + 8 : address of return value.
-//   RBX : address of the runtime function to call.
-//   R10 : number of arguments to the call.
-// Must preserve callee saved registers R12 and R13.
-void StubCode::GenerateCallToLeafRuntimeStub(Assembler* assembler) {
-  ASSERT((R12 != CTX) && (R13 != CTX));
-  const intptr_t isolate_offset = NativeArguments::isolate_offset();
-  const intptr_t argc_offset = NativeArguments::argc_offset();
-  const intptr_t argv_offset = NativeArguments::argv_offset();
-
-  __ EnterFrame(0);
-
-  // Reserve space for arguments and align frame before entering C++ world.
-  __ AddImmediate(RSP, Immediate(-sizeof(NativeArguments)));
-  if (OS::ActivationFrameAlignment() > 0) {
-    __ andq(RSP, Immediate(~(OS::ActivationFrameAlignment() - 1)));
-  }
-
-  // Pass NativeArguments structure by value.
-  // NOTE: the retvalue area in the NativeArguments structure is not setup
-  //       as leaf routines return the value in RAX.
-  __ movq(Address(RSP, isolate_offset), CTX);  // Set isolate in NativeArgs.
-  __ movq(Address(RSP, argc_offset), R10);  // Set argc in NativeArguments.
-  __ leaq(RAX, Address(RBP, R10, TIMES_8, 1 * kWordSize));  // Compute argv.
-  __ movq(Address(RSP, argv_offset), RAX);  // Set argv in NativeArguments.
-
-  // Make call to leaf runtime entry.
-  __ call(RBX);
-
-  // Set return value in caller's frame.
-  __ movq(RBX, Address(RSP, argv_offset));
-  __ addq(RBX, Immediate(1 * kWordSize));  // Retval is next to 1st argument.
-  __ movq(Address(RBX, 0), RAX);
-
-  __ LeaveFrame();
-  __ ret();
-}
-
-
 // Print the stop message.
 static void PrintStopMessage(const char* message) {
   OS::Print("Stop message: %s\n", message);