Question

对于以下代码，

proctype A() 
{ 
byte cond1;

time = time + 1;
time = time + 2;
t[0] = 3;
a[0] = 2;
do
:: (a[0] == 0)->break;
:: else -> a[0] = a[0] - 1;
    do
    :: (t[0] <= t[1])->break;
    od;
    if 
        :: (cond1 != 0) ->
           lock(mutex);
           time = time + 1;
           time = time + 2;
           t[0] = t[0] + 3;
           unlock(mutex);
        :: (cond1 == 0) -> time = time + 1;
    fi
od;
t[0] = 1000;
}

我收到以下错误，

unreached in proctype A
code.pml:15, state 20, "time = (time+1)"
code.pml:14, state 23, "((mutex==0))"
code.pml:14, state 23, "else"
code.pml:18, state 25, "time = (time+1)"
code.pml:12, state 26, "((mutex==0))"
code.pml:12, state 26, "((mutex==1))"
code.pml:12, state 29, "((mutex==0))"
code.pml:12, state 29, "((mutex==1))"
code.pml:45, state 31, "time = (time+2)"
code.pml:46, state 32, "t[0] = (t[0]+3)"
(7 of 43 states)

为什么会这样？ Promela不应该为cond1的每个值执行（cond1 == 0和cond1！= 0）。至少这是here中写的内容。

在验证期间，没有进行此类调用，因为有效地将在此模式下探索所有行为选项，一次一个。

Answer 1

我通过使用select语句解决了这个问题。

select (cond1 : 0..1);

Answer 2

cond1的初始值为零，并且永远不会更改 - 无论是Spin还是代码。因此条件cond1 != 0永远不会成立。要使该选项执行，您需要设置验证以生成cond1的其他/其他值，例如：

proctype A() 
{ 
  byte cond1;
  if
  :: cond1 = 0;
  :: cond1 = 1;
  /* … */
  fi;

  …
}

Promela中未解决的错误

2 个答案: