The Codex of the Machine Tongue

typedef struct {
    char  a;    // 偏移 0（1字节）
                // 填充 3 字节（使 int 按 4 字节对齐）
    int   b;    // 偏移 4（4字节）
    char  c;    // 偏移 8（1字节）
                // 填充 3 字节（结构体大小需为 4 的倍数）
} example;      // sizeof = 12

typedef struct {
    char  a;    // 偏移 0
                // 填充 7 字节
    long  b;    // 偏移 8
} tricky;       // sizeof = 16

typedef union {
    struct { long u; } t1;
    struct { int a[2]; } t2;
} u_t;

ldr x1, [x0]       // t1.u
ldr w1, [x0]       // t2.a[0]
ldr w1, [x0, #4]   // t2.a[1]

if (a > b) {
    x = 1;
} else {
    x = 2;
}

cmp w0, w1
b.le .Lelse
mov w2, #1
b .Lend
.Lelse:
mov w2, #2
.Lend:

x = (a > b) ? a : b;

cmp w0, w1
csel w2, w0, w1, gt

while (i < n) {
    i++;
}

b .Ltest
.Lloop:
add w0, w0, #1
.Ltest:
cmp w0, w1
b.lt .Lloop

for (int k = 0; k < 8; k++) { }

cmp w0, #8
b.ge .Lexit
.Lloop:
add w0, w0, #1
cmp w0, #8
b.lt .Lloop
.Lexit:

do { } while (condition);

.Lloop:
b.cond .Lloop

if (a != NULL && a->value > 0)

cbz x0, .Lskip
ldr w1, [x0, #offset]
cmp w1, #0
b.le .Lskip

if (x >= 0 && x <= 7)
// 等价于
if ((unsigned)x <= 7)

cmp w0, #7
b.hi .Lskip

square:
mul w0, w0, w0
ret

stp x29, x30, [sp, #-32]!
mov x29, sp
str x19, [sp, #16]

ldr x19, [sp, #16]
ldp x29, x30, [sp], #32
ret

stp x29, x30, [sp, #-32]!
// → 栈帧大小 = 32 字节

cbz w3, .Lbase

stp x29, x30, [sp, #-32]!
mov x29, sp
str x19, [sp, #16]

bl recursive_func

ldr x19, [sp, #16]
ldp x29, x30, [sp], #32
ret

.Lbase:
mov w0, #0
ret