Implements a new API to set a function entry hook for profiling.

src/x64/code-stubs-x64.cc

 // Copyright 2012 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 6402 matching lines @@
   __ movq(r9, FieldOperand(rbx, JSObject::kElementsOffset));
   __ SmiToInteger32(r11, rcx);
   __ StoreNumberToDoubleElements(rax,
                                  r9,
                                  r11,
                                  xmm0,
                                  &slow_elements);
   __ ret(0);
 }
 
+
+void ProfileEntryHookStub::MaybeCallEntryHook(MacroAssembler* masm) {
+  if (entry_hook_ != NULL) {
+    ProfileEntryHookStub stub;
+    masm->CallStub(&stub);
+  }
+}
+
+
+void ProfileEntryHookStub::Generate(MacroAssembler* masm) {
+  // Save volatile registers.
+  // Live registers at this point are the same as at the start of any
+  // JS function:
+  //   o rdi: the JS function object being called (i.e. ourselves)
+  //   o rsi: our context
+  //   o rbp: our caller's frame pointer
+  //   o rsp: stack pointer (pointing to return address)
+  //   o rcx: rcx is zero for method calls and non-zero for function calls.
+#ifdef _WIN64
+  const int kNumSavedRegisters = 1;
+
+  __ push(rcx);
+#else
+  const int kNumSavedRegisters = 3;
+
+  __ push(rcx);
+  __ push(rdi);
+  __ push(rsi);
+#endif
+
+  // Calculate the original stack pointer and store it in the second arg.
+#ifdef _WIN64
+  __ lea(rdx, Operand(rsp, kNumSavedRegisters * kPointerSize));
+#else
+  __ lea(rsi, Operand(rsp, kNumSavedRegisters * kPointerSize));
+#endif
+
+  // Calculate the function address to the first arg.
+#ifdef _WIN64
+  __ movq(rcx, Operand(rdx, 0));
+  __ subq(rcx, Immediate(Assembler::kShortCallInstructionLength));
+#else
+  __ movq(rdi, Operand(rsi, 0));
+  __ subq(rdi, Immediate(Assembler::kShortCallInstructionLength));
+#endif
+
+  // Call the entry hook function.
+  __ movq(rax, &entry_hook_, RelocInfo::NONE);
+  __ movq(rax, Operand(rax, 0));
+
+  AllowExternalCallThatCantCauseGC scope(masm);
+
+  const int kArgumentCount = 2;
+  __ PrepareCallCFunction(kArgumentCount);
+  __ CallCFunction(rax, kArgumentCount);
+
+  // Restore volatile regs.
+#ifdef _WIN64
+  __ pop(rcx);
+#else
+  __ pop(rsi);
+  __ pop(rdi);
+  __ pop(rcx);
+#endif
+
+  __ Ret();
+}
+
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64