arch/specific/x86-64/objc-nil-receiver.c

/* Internal API: nil receiver type for polar-objc.
   Copyright (C) 2022-2025 Michael Malicoat <[email protected]>
 
   This file is part of polar-objc.
 
   polar-objc is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
   License as published by the Free Software Foundation; either version 3, or (at your option) any later version.
 
   polar-objc is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
   warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
   details.
 
   You should have received a copy of the GNU General Public License along with this program; see the file LICENSE.  If
   not, see <http://www.gnu.org/licenses/>.
*/
 
// Public ==============================================================================================================
 
#if defined(OBJC_PLATFORM_POSIX) || defined(OBJC_PLATFORM_WINDOWS)
 
id
polar_runtime_event_message_recipient_needed( id self, SEL _cmd )
{
  return POLAR_RUNTIME_EVENT->message_recipient_needed(_cmd);
}
#endif
 
#if defined(OBJC_PLATFORM_WINDOWS) // Windows X64 ABI
asm
(
  ".global _i_Nil__message_recipient_0x00\n"
 
  "_i_Nil__message_recipient_0x00:\n\t"
    "pushq   %rbp\n\t"
    "movq    %rsp, %rbp\n\t"
 
    "pushq   %rbx\n\t"  // GCC sometimes uses this as a base pointer
 
    "pushq   %rdx\n\t"  // Parameter 2
    "pushq   %r8\n\t"   // Parameter 3
    "pushq   %r9\n\t"   // Parameter 4
 
    "pushq   %rdx\n\t"  // Save _cmd for later use
    "pushq   %rcx\n\t"  // Save `self` for later use
 
    "call    polar_runtime_event_message_recipient_needed\n\t"
 
    // Did _polar_runtime_event_message_recipient_needed() return nil?
    "popq    %rcx\n\t"
    "cmpq    %rax, %rcx\n\t"
 
    // We have a message recipient that is not nil
    "jne     message_lookup\n\t"
 
    // No message recipient; restore registers and return NULL
    "popq    %rdx\n\t"
 
    "popq    %r9\n\t"
    "popq    %r8\n\t"
    "popq    %rdx\n\t"
 
    "popq    %rbx\n\t"
 
    "movq    %rbp, %rsp\n\t"
    "popq    %rbp\n\t"
 
    // return NULL
    "xorq    %rax, %rax\n\t"
    "ret\n\t"
 
  "message_lookup:\n\t"
    "popq    %rdx\n\t"  // Restore _cmd
    "pushq   %rax\n\t"  // Push our new `self`` for later use
 
    "movq    %rax, %rcx\n\t"
 
    "call    objc_msg_lookup\n\t"
    "movq    %rax, %r11\n\t"  // Move the returned IMP to R11
 
    "popq    %rcx\n\t"  // Pop our new `self`
 
    "popq    %r9\n\t"  // Restore registers for the jump into the target method
    "popq    %r8\n\t"
    "popq    %rdx\n\t"
 
    "popq    %rbx\n\t"
 
    "movq    %rbp, %rsp\n\t"
    "popq    %rbp\n\t"
 
    "jmpq    *%r11\n"  // Jump to the target method, which will return to the caller for us
);
#elif defined(OBJC_PLATFORM_POSIX) // System V ABI for AMD64
asm
(
  ".global _i_Nil__message_recipient_0x00\n"
 
  "_i_Nil__message_recipient_0x00:\n\t"
    "pushq   %rbp\n\t"
    "movq    %rsp, %rbp\n\t"
 
    "pushq   %rbx\n\t"  // GCC sometimes uses this as a base pointer
    "pushq   %rax\n\t"  // If the target method accepts varargs, then this value is important
 
    "pushq   %rsi\n\t"  // Parameter 2
    "pushq   %rdx\n\t"  // Parameter 3
    "pushq   %rcx\n\t"  // Parameter 4
    "pushq   %r8\n\t"   // Parameter 5
    "pushq   %r9\n\t"   // Parameter 6
 
    "pushq   %rsi\n\t"  // Save _cmd for later use
    "pushq   %rdi\n\t"  // Save self for later use
 
    "subq    $8, %rsp\n\t"
    "call    polar_runtime_event_message_recipient_needed\n\t"
    "addq    $8, %rsp\n\t"
 
    // Did  polar_runtime_event_message_recipient_needed() return nil?
    "popq    %rdi\n\t"
    "cmpq    %rax, %rdi\n\t"
 
    // We have a message recipient that is not nil
    "jne     message_lookup\n\t"
 
    // No message recipient; restore registers and return NULL
    "popq    %rsi\n\t"
 
    "popq    %r9\n\t"
    "popq    %r8\n\t"
    "popq    %rcx\n\t"
    "popq    %rdx\n\t"
    "popq    %rsi\n\t"
 
    "popq    %rax\n\t"
    "popq    %rbx\n\t"
 
    "movq    %rbp, %rsp\n\t"
    "popq    %rbp\n\t"
 
    // return NULL
    "xorq    %rax, %rax\n\t"
    "ret\n\t"
 
  "message_lookup:\n\t"
    "popq    %rsi\n\t"  // Restore _cmd
    "pushq   %rax\n\t"  // Push our new `self`` for later use
 
    "movq    %rax, %rdi\n\t"
 
    "subq    $8, %rsp\n\t"
    "call    objc_msg_lookup\n\t"
    "addq    $8, %rsp\n\t"
 
    "movq    %rax, %r11\n\t"  // Move the returned IMP to R11
 
    "popq    %rdi\n\t"  // Pop our new `self`
 
    "popq    %r9\n\t"   // Restore registers for the jump into the target method
    "popq    %r8\n\t"
    "popq    %rcx\n\t"
    "popq    %rdx\n\t"
    "popq    %rsi\n\t"
 
    "popq    %rax\n\t"
    "popq    %rbx\n\t"
 
    "movq    %rbp, %rsp\n\t"
    "popq    %rbp\n\t"
 
    "jmpq    *%r11\n"  // Jump to the target method, which will return to the caller for us
);
#else
  #include "source/polar-internals/arch/generic/objc-nil-receiver.h"
#endif