main.cpp

struct size_t {

};

int do_read_from_somewhere(size_t* output) {
  size_t out;
  *output = out;

  return 0;
}

int main() {
  size_t buffer;
  do_read_from_somewhere(&buffer);

  return 0;
}

main.s

	.file	"main.cpp"
	.text
	.globl	_Z22do_read_from_somewhereP6size_t
	.def	_Z22do_read_from_somewhereP6size_t;	.scl	2;	.type	32;	.endef
	.seh_proc	_Z22do_read_from_somewhereP6size_t
_Z22do_read_from_somewhereP6size_t:
.LFB0:
	pushq	%rbp
	.seh_pushreg	%rbp
	movq	%rsp, %rbp
	.seh_setframe	%rbp, 0
	subq	$16, %rsp
	.seh_stackalloc	16
	.seh_endprologue
	movq	%rcx, 16(%rbp)
	movl	$0, %eax
	addq	$16, %rsp
	popq	%rbp
	ret
	.seh_endproc
	.def	__main;	.scl	2;	.type	32;	.endef
	.globl	main
	.def	main;	.scl	2;	.type	32;	.endef
	.seh_proc	main
main:
.LFB1:
  ; push the current value of rbp onto the stack. this is done to preserve the existing value when we pop it later
	pushq	%rbp
	.seh_pushreg	%rbp
	; move the current stack pointer to rbp
	movq	%rsp, %rbp
	.seh_setframe	%rbp, 0
	; subtract 48 from the stack pointer - used for SEH
	subq	$48, %rsp
	.seh_stackalloc	48
	.seh_endprologue
	; invoke __main, whatever this is
	call	__main
	; wat?
	leaq	-1(%rbp), %rax
	; wat wat?
	movq	%rax, %rcx
	; call our function
	call	_Z22do_read_from_somewhereP6size_t
	; set the eax value to 0 - This is the main's return value.
	movl	$0, %eax
	; restore 48 bytes to the stack pointer (remember this is for SEH?)
	addq	$48, %rsp
	; pop the previous value of rbp, restoring it to the original value when we pushed it at the start of .LFB1.
	popq	%rbp
	ret
	.seh_endproc
	.ident	"GCC: (Rev3, Built by MSYS2 project) 5.2.0"