libgcc/config/i386/sol2-c1.S

/* crt1.s for Solaris 2, x86

   Copyright (C) 1993-2021 Free Software Foundation, Inc.
   Written By Fred Fish, Nov 1992

This file 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.

This file 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.

Under Section 7 of GPL version 3, you are granted additional
permissions described in the GCC Runtime Library Exception, version
3.1, as published by the Free Software Foundation.

You should have received a copy of the GNU General Public License and
a copy of the GCC Runtime Library Exception along with this program;
see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
<http://www.gnu.org/licenses/>.  */


/* This file takes control of the process from the kernel, as specified
   in section 3 of the System V Application Binary Interface, Intel386
   Processor Supplement.  It has been constructed from information obtained
   from the ABI, information obtained from single stepping existing
   Solaris executables through their startup code with gdb, and from
   information obtained by single stepping executables on other i386 SVR4
   implementations.  This file is the first thing linked into any
   executable.  */

#ifndef GCRT1
	.ident	"GNU C crt1.s"
#define CLEANUP	_cleanup
#else
/* This is a modified crt1.s by J.W.Hawtin <oolon@ankh.org> 15/8/96, 
   to allow program profiling, by calling monstartup on entry and _mcleanup 
   on exit.  */
	.ident	"GNU C gcrt1.s"
#define CLEANUP _mcleanup
#endif
	.weak	_cleanup
	.weak	_DYNAMIC
	.text

/* Start creating the initial frame by pushing a NULL value for the return
   address of the initial frame, and mark the end of the stack frame chain
   (the innermost stack frame) with a NULL value, per page 3-32 of the ABI.
   Initialize the first stack frame pointer in %ebp (the contents of which
   are unspecified at process initialization).  */

	.globl	_start
_start:
	pushl	$0x0
	pushl	$0x0
	movl	%esp,%ebp

/* As specified per page 3-32 of the ABI, %edx contains a function 
   pointer that should be registered with atexit(), for proper
   shared object termination.  Just push it onto the stack for now
   to preserve it.  We want to register _cleanup() first.  */

	pushl	%edx

/* Check to see if there is an _cleanup() function linked in, and if
   so, register it with atexit() as the last thing to be run by
   atexit().  */

	movl	$CLEANUP,%eax
	testl	%eax,%eax
	je	.L1
	pushl	$CLEANUP
	call	atexit
	addl	$0x4,%esp
.L1:

/* Now check to see if we have an _DYNAMIC table, and if so then
   we need to register the function pointer previously in %edx, but
   now conveniently saved on the stack as the argument to pass to
   atexit().  */

	movl	$_DYNAMIC,%eax
	testl	%eax,%eax
	je	.L2
	call	atexit
.L2:

/* Register _fini() with atexit().  We will take care of calling _init()
   directly.  */

	pushl	$_fini
	call	atexit

#ifdef GCRT1
/* Start profiling.  */

        pushl %ebp
        movl %esp,%ebp
        pushl $_etext
        pushl $_start
        call monstartup
        addl $8,%esp
	popl %ebp
#endif

/* Compute the address of the environment vector on the stack and load
   it into the global variable _environ.  Currently argc is at 8 off
   the frame pointer.  Fetch the argument count into %eax, scale by the
   size of each arg (4 bytes) and compute the address of the environment
   vector which is 16 bytes (the two zero words we pushed, plus argc,
   plus the null word terminating the arg vector) further up the stack,
   off the frame pointer (whew!).  */

	movl	8(%ebp),%eax
	leal	16(%ebp,%eax,4),%edx
	movl	%edx,_environ

/* Push the environment vector pointer, the argument vector pointer,
   and the argument count on to the stack to set up the arguments
   for _init(), _fpstart(), and main().  Note that the environment
   vector pointer and the arg count were previously loaded into
   %edx and %eax respectively.  The only new value we need to compute
   is the argument vector pointer, which is at a fixed address off
   the initial frame pointer.  */

/* Make sure the stack is properly aligned.  */
	andl $0xfffffff0,%esp
	subl $4,%esp

	pushl	%edx
	leal	12(%ebp),%edx
	pushl	%edx
	pushl	%eax

/* Call _init(argc, argv, environ), _fpstart(argc, argv, environ), and
   main(argc, argv, environ).  */

	call	_init
	call	__fpstart
	call	main

/* Pop the argc, argv, and environ arguments off the stack, push the
   value returned from main(), and call exit().  */

	addl	$12,%esp
	pushl	%eax
	call	exit

/* An inline equivalent of _exit, as specified in Figure 3-26 of the ABI.  */

	pushl	$0x0
	movl	$0x1,%eax
	lcall	$7,$0

/* If all else fails, just try a halt!  */

	hlt
	.type	_start,@function
	.size	_start,.-_start

#ifndef GCRT1
/* A dummy profiling support routine for non-profiling executables,
   in case we link in some objects that have been compiled for profiling.  */

	.weak	_mcount
_mcount:
	ret
	.type	_mcount,@function
	.size	_mcount,.-_mcount
#endif