ARM64 normal and variadic calling conventions

test.c

// xcrun -sdk iphoneos clang -O3 -arch arm64 -S test.c
#import <stdarg.h>
#import <stdio.h>

void normal(int a, int b, int c, int d, int e, int f, int g, int h) {
    printf("%d %d %d %d %d %d %d %d", a, b, c, d, e, f, g, h);
}

void normal_target(int a, int b, int c, int d, int e, int f, int g, int h);

void call_normal() {
    normal_target(1, 2, 3, 4, 5, 6, 7, 8);
}

void vararg(int a, ...) {
    va_list args;
    va_start(args, a);
    int b = va_arg(args, int);
    int c = va_arg(args, int);
    int d = va_arg(args, int);
    int e = va_arg(args, int);
    int f = va_arg(args, int);
    int g = va_arg(args, int);
    int h = va_arg(args, int);
    printf("%d %d %d %d %d %d %d %d", a, b, c, d, e, f, g, h);
}

void vararg_target(int a, ...);

void call_vararg() {
    vararg_target(1, 2, 3, 4, 5, 6, 7, 8);
}

test.s

	.section	__TEXT,__text,regular,pure_instructions
	.ios_version_min 10, 3
	.globl	_normal
	.p2align	2
_normal:                                ; @normal
; BB#0:
	sub	sp, sp, #80             ; =80
	stp	x29, x30, [sp, #64]     ; 8-byte Folded Spill
	add	x29, sp, #64            ; =64
                                        ; kill: %W7<def> %W7<kill> %X7<def>
                                        ; kill: %W6<def> %W6<kill> %X6<def>
                                        ; kill: %W5<def> %W5<kill> %X5<def>
                                        ; kill: %W4<def> %W4<kill> %X4<def>
                                        ; kill: %W3<def> %W3<kill> %X3<def>
                                        ; kill: %W2<def> %W2<kill> %X2<def>
                                        ; kill: %W1<def> %W1<kill> %X1<def>
                                        ; kill: %W0<def> %W0<kill> %X0<def>
	stp	x6, x7, [sp, #48]
	stp	x4, x5, [sp, #32]
	stp	x2, x3, [sp, #16]
Lloh0:
	adrp	x8, L_.str@PAGE
Lloh1:
	add	x8, x8, L_.str@PAGEOFF
	stp		x0, x1, [sp]
	mov	 x0, x8
	bl	_printf
	ldp	x29, x30, [sp, #64]     ; 8-byte Folded Reload
	add	sp, sp, #80             ; =80
	ret
	.loh AdrpAdd	Lloh0, Lloh1

	.globl	_call_normal
	.p2align	2
_call_normal:                           ; @call_normal
; BB#0:
	orr	w0, wzr, #0x1
	orr	w1, wzr, #0x2
	orr	w2, wzr, #0x3
	orr	w3, wzr, #0x4
	mov	w4, #5
	orr	w5, wzr, #0x6
	orr	w6, wzr, #0x7
	orr	w7, wzr, #0x8
	b	_normal_target

	.globl	_vararg
	.p2align	2
_vararg:                                ; @vararg
; BB#0:
	sub	sp, sp, #96             ; =96
	stp	x29, x30, [sp, #80]     ; 8-byte Folded Spill
	add	x29, sp, #80            ; =80
                                        ; kill: %W0<def> %W0<kill> %X0<def>
	add	x8, x29, #16            ; =16
	stur	x8, [x29, #-8]
	orr	x8, x8, #0x8
	stur	x8, [x29, #-8]
	ldr	w9, [x29, #16]
	add	x10, x8, #8             ; =8
	stur	x10, [x29, #-8]
	ldr		w8, [x8]
	add	x11, x10, #8            ; =8
	stur	x11, [x29, #-8]
	ldr		w10, [x10]
	add	x12, x11, #8            ; =8
	stur	x12, [x29, #-8]
	ldr		w11, [x11]
	add	x13, x12, #8            ; =8
	stur	x13, [x29, #-8]
	ldr		w12, [x12]
	add	x14, x13, #8            ; =8
	stur	x14, [x29, #-8]
	ldr		w13, [x13]
	add	x15, x14, #8            ; =8
	stur	x15, [x29, #-8]
	ldr		w14, [x14]
	stp	x13, x14, [sp, #48]
	stp	x11, x12, [sp, #32]
	stp	x8, x10, [sp, #16]
Lloh2:
	adrp	x8, L_.str@PAGE
Lloh3:
	add	x8, x8, L_.str@PAGEOFF
	stp		x0, x9, [sp]
	mov	 x0, x8
	bl	_printf
	ldp	x29, x30, [sp, #80]     ; 8-byte Folded Reload
	add	sp, sp, #96             ; =96
	ret
	.loh AdrpAdd	Lloh2, Lloh3

	.globl	_call_vararg
	.p2align	2
_call_vararg:                           ; @call_vararg
; BB#0:
	sub	sp, sp, #80             ; =80
	stp	x29, x30, [sp, #64]     ; 8-byte Folded Spill
	add	x29, sp, #64            ; =64
	orr	w8, wzr, #0x8
	str	x8, [sp, #48]
	orr	w8, wzr, #0x7
	orr	w9, wzr, #0x6
	stp	x9, x8, [sp, #32]
	mov	w8, #5
	orr	w9, wzr, #0x4
	stp	x9, x8, [sp, #16]
	orr	w8, wzr, #0x3
	orr	w9, wzr, #0x2
	stp		x9, x8, [sp]
	orr	w0, wzr, #0x1
	bl	_vararg_target
	ldp	x29, x30, [sp, #64]     ; 8-byte Folded Reload
	add	sp, sp, #80             ; =80
	ret

	.section	__TEXT,__cstring,cstring_literals
L_.str:                                 ; @.str
	.asciz	"%d %d %d %d %d %d %d %d"


.subsections_via_symbols