swiftc -emit-assembly -Osize -target arm64-apple-macos14 test.swift

arm64-apple-macos13.asm

	.section	__TEXT,__text,regular,pure_instructions
	.build_version macos, 13, 0	sdk_version 15, 0
	.globl	_main
	.p2align	2
_main:
	mov	w0, #0
	ret

	.private_extern	_$s4test4mainSiyF
	.globl	_$s4test4mainSiyF
	.p2align	2
_$s4test4mainSiyF:
	.cfi_startproc
	stp	x29, x30, [sp, #-16]!
	mov	x29, sp
	.cfi_def_cfa w29, 16
	.cfi_offset w30, -8
	.cfi_offset w29, -16
	mov	w0, #14
	mov	x1, #0
	mov	x2, #0
	bl	_$ss26_stdlib_isOSVersionAtLeastyBi1_Bw_BwBwtF
	tst	w0, #0x1
	mov	w8, #1
	cinc	x0, x8, ne
	ldp	x29, x30, [sp], #16
	ret
	.cfi_endproc

	.section	__TEXT,__swift5_entry,regular,no_dead_strip
	.p2align	2, 0x0
l_entry_point:
	.long	_main-l_entry_point
	.long	0

	.private_extern	___swift_reflection_version
	.section	__TEXT,__const
	.globl	___swift_reflection_version
	.weak_definition	___swift_reflection_version
	.p2align	1, 0x0
___swift_reflection_version:
	.short	3

	.no_dead_strip	l_entry_point
	.no_dead_strip	___swift_reflection_version
	.no_dead_strip	_main
	.linker_option "-lswift_Concurrency"
	.linker_option "-lswiftCore"
	.linker_option "-lswift_StringProcessing"
	.linker_option "-lobjc"
	.linker_option "-lswiftCompatibilityPacks"
	.section	__DATA,__objc_imageinfo,regular,no_dead_strip
L_OBJC_IMAGE_INFO:
	.long	0
	.long	100665152

.subsections_via_symbols

arm64-apple-macos14.asm

	.section	__TEXT,__text,regular,pure_instructions
	.build_version macos, 14, 0	sdk_version 15, 0
	.globl	_main
	.p2align	2
_main:
	mov	w0, #0
	ret

	.private_extern	_$s4test4mainSiyF
	.globl	_$s4test4mainSiyF
	.p2align	2
_$s4test4mainSiyF:
	mov	w0, #2
	ret

	.section	__TEXT,__swift5_entry,regular,no_dead_strip
	.p2align	2, 0x0
l_entry_point:
	.long	_main-l_entry_point
	.long	0

	.private_extern	___swift_reflection_version
	.section	__TEXT,__const
	.globl	___swift_reflection_version
	.weak_definition	___swift_reflection_version
	.p2align	1, 0x0
___swift_reflection_version:
	.short	3

	.no_dead_strip	l_entry_point
	.no_dead_strip	___swift_reflection_version
	.no_dead_strip	_main
	.linker_option "-lswift_Concurrency"
	.linker_option "-lswiftCore"
	.linker_option "-lswift_StringProcessing"
	.linker_option "-lobjc"
	.section	__DATA,__objc_imageinfo,regular,no_dead_strip
L_OBJC_IMAGE_INFO:
	.long	0
	.long	100665152

.subsections_via_symbols

test.swift

func main() -> Int {
    if #available(macOS 14, *) {
        return 2
    }
    return 1
}