clang_arm64_repro.c

// The buffer is terminated with "\n\0"
int count(const char *p) {
    int n = 0;
    while (*p) {
        while (*p != '\n') p++;
        n++;
        while (*p == '\n') p++;
    }
    return n;
}

clang_arm64_repro.s

	.section	__TEXT,__text,regular,pure_instructions
	.build_version macos, 11, 0
	.globl	_count                          ; -- Begin function count
	.p2align	2
_count:                                 ; @count
	.cfi_startproc
; %bb.0:                                ; %entry
	ldrb	w9, [x0]
	cbz	w9, LBB0_6
; %bb.1:                                ; %while.cond1.preheader.preheader
	mov	w8, #0
	and	w9, w9, #0xff
	cmp	w9, #10                         ; =10
	b.eq	LBB0_3
LBB0_2:                                 ; %while.cond1.while.cond1_crit_edge
                                        ; =>This Inner Loop Header: Depth=1
	ldrb	w9, [x0, #1]!
	cmp	w9, #10                         ; =10
	b.ne	LBB0_2
LBB0_3:                                 ; %while.body8
                                        ; =>This Inner Loop Header: Depth=1
	ldrb	w9, [x0, #1]!
	cmp	w9, #10                         ; =10
	b.eq	LBB0_3
; %bb.4:                                ; %while.cond.loopexit
                                        ;   in Loop: Header=BB0_3 Depth=1
	add	w8, w8, #1                      ; =1
	cbz	w9, LBB0_7
; %bb.5:                                ; %while.cond1.preheader
                                        ;   in Loop: Header=BB0_3 Depth=1
	and	w9, w9, #0xff
	cmp	w9, #10                         ; =10
	b.ne	LBB0_2
	b	LBB0_3
LBB0_6:
	mov	w8, #0
LBB0_7:                                 ; %while.end11
	mov	x0, x8
	ret
	.cfi_endproc
                                        ; -- End function
.subsections_via_symbols