Removing redundant stubs for API functions.

src/x64/macro-assembler-x64.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 309 matching lines @@
   MaybeObject* result = stub->TryGetCode();
   if (!result->IsFailure()) {
     call(Handle<Code>(Code::cast(result->ToObjectUnchecked())),
          RelocInfo::CODE_TARGET);
   }
   return result;
 }
 
 
 void MacroAssembler::TailCallStub(CodeStub* stub) {
-  ASSERT(allow_stub_calls());  // calls are not allowed in some stubs
+  ASSERT(allow_stub_calls());  // Calls are not allowed in some stubs.
   Jump(stub->GetCode(), RelocInfo::CODE_TARGET);
 }
 
 
 MaybeObject* MacroAssembler::TryTailCallStub(CodeStub* stub) {
   ASSERT(allow_stub_calls());  // Calls are not allowed in some stubs.
   MaybeObject* result = stub->TryGetCode();
   if (!result->IsFailure()) {
     jmp(Handle<Code>(Code::cast(result->ToObjectUnchecked())),
         RelocInfo::CODE_TARGET);
@@ skipping 108 matching lines @@
 
   // TODO(1236192): Most runtime routines don't need the number of
   // arguments passed in because it is constant. At some point we
   // should remove this need and make the runtime routine entry code
   // smarter.
   Set(rax, num_arguments);
   JumpToExternalReference(ext, result_size);
 }
 
 
+MaybeObject* MacroAssembler::TryTailCallExternalReference(
+    const ExternalReference& ext, int num_arguments, int result_size) {
+  // ----------- S t a t e -------------
+  //  -- rsp[0] : return address
+  //  -- rsp[8] : argument num_arguments - 1
+  //  ...
+  //  -- rsp[8 * num_arguments] : argument 0 (receiver)
+  // -----------------------------------
+
+  // TODO(1236192): Most runtime routines don't need the number of
+  // arguments passed in because it is constant. At some point we
+  // should remove this need and make the runtime routine entry code
+  // smarter.
+  Set(rax, num_arguments);
+  return TryJumpToExternalReference(ext, result_size);
+}
+
+
 void MacroAssembler::TailCallRuntime(Runtime::FunctionId fid,
                                      int num_arguments,
                                      int result_size) {
   TailCallExternalReference(ExternalReference(fid), num_arguments, result_size);
 }
 
 
+MaybeObject* MacroAssembler::TryTailCallRuntime(Runtime::FunctionId fid,
+                                                int num_arguments,
+                                                int result_size) {
+  return TryTailCallExternalReference(ExternalReference(fid),
+                                      num_arguments,
+                                      result_size);
+}
+
+
 static int Offset(ExternalReference ref0, ExternalReference ref1) {
   int64_t offset = (ref0.address() - ref1.address());
   // Check that fits into int.
   ASSERT(static_cast<int>(offset) == offset);
   return static_cast<int>(offset);
 }
 
 
-void MacroAssembler::PrepareCallApiFunction(int stack_space) {
-  EnterApiExitFrame(stack_space, 0);
+void MacroAssembler::PrepareCallApiFunction(int stack_space, int argc) {
+#ifdef _WIN64
+  // We need to prepare a slot for result handle on stack and put
+  // a pointer to it into 1st arg register.
+  int register_based_args = argc > 3 ? 3 : argc;
+  EnterApiExitFrame(stack_space, argc - register_based_args + 1);
+
+  int return_value_slot = (argc > 3 ? argc - 3 + 1 : 4);
+  // rcx must be used to pass the pointer to the return value slot.
+  lea(rcx, Operand(rsp, return_value_slot * kPointerSize));
+#else
+  EnterApiExitFrame(stack_space, argc);
+#endif
 }
 
 
-void MacroAssembler::CallApiFunctionAndReturn(ApiFunction* function) {
+MaybeObject* MacroAssembler::TryCallApiFunctionAndReturn(
+    ApiFunction* function) {
   Label empty_result;
   Label prologue;
   Label promote_scheduled_exception;
   Label delete_allocated_handles;
   Label leave_exit_frame;
   Label write_back;
 
   ExternalReference next_address =
       ExternalReference::handle_scope_next_address();
   const int kNextOffset = 0;
@@ skipping 42 matching lines @@
 
   // Check if the function scheduled an exception.
   movq(rsi, scheduled_exception_address);
   Cmp(Operand(rsi, 0), Factory::the_hole_value());
   j(not_equal, &promote_scheduled_exception);
 
   LeaveExitFrame();
   ret(0);
 
   bind(&promote_scheduled_exception);
-  TailCallRuntime(Runtime::kPromoteScheduledException, 0, 1);
+  MaybeObject* result = TryTailCallRuntime(Runtime::kPromoteScheduledException,
+                                           0, 1);
+  if (result->IsFailure()) {
+    return result;
+  }
 
   bind(&empty_result);
   // It was zero; the result is undefined.
   Move(rax, Factory::undefined_value());
   jmp(&prologue);
 
   // HandleScope limit has changed. Delete allocated extensions.
   bind(&delete_allocated_handles);
   movq(Operand(base_reg, kLimitOffset), prev_limit_reg);
   movq(prev_limit_reg, rax);
   movq(rax, ExternalReference::delete_handle_scope_extensions());
   call(rax);
   movq(rax, prev_limit_reg);
   jmp(&leave_exit_frame);
+
+  return result;
 }
 
 
 void MacroAssembler::JumpToExternalReference(const ExternalReference& ext,
                                              int result_size) {
   // Set the entry point and jump to the C entry runtime stub.
   movq(rbx, ext);
   CEntryStub ces(result_size);
   jmp(ces.GetCode(), RelocInfo::CODE_TARGET);
 }
 
 
+MaybeObject* MacroAssembler::TryJumpToExternalReference(
+    const ExternalReference& ext, int result_size) {
+  // Set the entry point and jump to the C entry runtime stub.
+  movq(rbx, ext);
+  CEntryStub ces(result_size);
+  return TryTailCallStub(&ces);
+}
+
+
 void MacroAssembler::InvokeBuiltin(Builtins::JavaScript id, InvokeFlag flag) {
   // Calls are not allowed in some stubs.
   ASSERT(flag == JUMP_FUNCTION || allow_stub_calls());
 
   // Rely on the assertion to check that the number of provided
   // arguments match the expected number of arguments. Fake a
   // parameter count to avoid emitting code to do the check.
   ParameterCount expected(0);
   GetBuiltinEntry(rdx, id);
   InvokeCode(rdx, expected, expected, flag);
@@ skipping 1156 matching lines @@
 void MacroAssembler::EnterApiExitFrame(int stack_space,
                                        int argc,
                                        int result_size) {
   EnterExitFramePrologue(false);
 
   // Setup argv in callee-saved register r12. It is reused in LeaveExitFrame,
   // so it must be retained across the C-call.
   int offset = StandardFrameConstants::kCallerSPOffset - kPointerSize;
   lea(r12, Operand(rbp, (stack_space * kPointerSize) + offset));
 
+#ifndef _WIN64
+  ASSERT(argc <= 6);  // EnterApiExitFrame supports only register based args.

[antonm, 2010/11/15 16:22:06]

Sorry, I still don't understand what.  What will happen if I write something
like:

for (var i = 0; i < 1000; i++) obj.appFunction(1, 2, 3, 4, 5, 6, 7, 8, 9)?

Will v8 just crash?

[SeRya, 2010/11/15 16:37:50]

Currently it's used only for getters for x64 (yet). But in case it was the
arguments would be: argc is 1 (because InvocationCallback accepts single
argument - reference to v8::Arguments). stack_space will be 13: receiver + 9 JS
arguments + 3-element array to represent v8::Arguments::implicit_values_.

+#endif
+
   EnterExitFrameEpilogue(result_size, argc);
 }
 
 
 void MacroAssembler::LeaveExitFrame(int result_size) {
   // Registers:
   // r12 : argv
 
   // Get the return address from the stack and restore the frame pointer.
   movq(rcx, Operand(rbp, 1 * kPointerSize));
@@ skipping 525 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64