| //===- x86_64 implementation of the get_start_args_addr function -*- C++ -*===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| %%begin() |
| |
| namespace __llvm_libc { |
| |
| __attribute__((always_inline)) inline uintptr_t get_start_args_addr() { |
| // NOTE: For __builtin_frame_address to work reliably across compilers, |
| // architectures and various optimization levels, the TU including this file |
| // should be compiled with -fno-omit-frame-pointer. |
| return reinterpret_cast<uintptr_t>(__builtin_frame_address(0)) + |
| // The x86_64 call instruction pushes resume address on to the stack. |
| // Next, The x86_64 SysV ABI also pushes the frame pointer on the |
| // stack. Hence, we look past these items to get to the start args. |
| sizeof(uintptr_t) * 2; |
| } |
| |
| } // namespace __llvm_libc |
