store

把寄存器的值保存到内存中

/* store register 'r' in lvalue 'v' */
ST_FUNC void store(int r, SValue *v)
{
    int fr, bt, ft, fc;

    ft = v->type.t;
    fc = v->c.ul;
    fr = v->r & VT_VALMASK;
    bt = ft & VT_BTYPE;
    /* XXX: incorrect if float reg to reg */
    if (bt == VT_FLOAT) {
        o(0xd9); /* fsts */
        r = 2;
    } else if (bt == VT_DOUBLE) {
        o(0xdd); /* fstpl */
        r = 2;
    } else if (bt == VT_LDOUBLE) {
        o(0xc0d9); /* fld %st(0) */
        o(0xdb); /* fstpt */
        r = 7;
    } else {

        16 位 prefix

        if (bt == VT_SHORT)
            o(0x66);
        if (bt == VT_BYTE || bt == VT_BOOL)
            o(0x88); 8 位偏移
        else
            o(0x89); 32 位
    }
    if (fr == VT_CONST ||
        fr == VT_LOCAL ||
        (v->r & VT_LVAL)) {
        gen_modrm(r, v->r, v->sym, fc);
    } else if (fr != r) {
        该判断是多余的？
        o(0xc0 + fr + r * 8); /* mov r, fr */
    }
}