> On Nov 16, 2017, at 6:24 PM, Martin Sebor <mse...@gmail.com> wrote:
>>
>> In my current local implementation, I used the following routine to get the
>> range info: (and use the MINMAXLEN[1]+1 for the length of the non-constant
>> string)
>>
>> /* Determine the minimum and maximum value or string length that ARG
>> refers to and store each in the first two elements of MINMAXLEN.
>> For expressions that point to strings of unknown lengths that are
>> character arrays, use the upper bound of the array as the maximum
>> length. For example, given an expression like 'x ? array : "xyz"'
>> and array declared as 'char array[8]', MINMAXLEN[0] will be set
>> to 3 and MINMAXLEN[1] to 7, the longest string that could be
>> stored in array.
>> Return true if the range of the string lengths has been obtained
>> from the upper bound of an array at the end of a struct. Such
>> an array may hold a string that's longer than its upper bound
>> due to it being used as a poor-man's flexible array member. */
>>
>> bool
>> get_range_strlen (tree arg, tree minmaxlen[2])
>> {
>> }
>>
>> However, this routine currently miss a very obvious case as the following:
>>
>> char s[100] = {'a','b','c','d’};
>>
>> __builtin_strcmp(s, "abc") != 0
>>
>> So, I have to change this routine to include such common case.
>
> There was a discussion some time ago about converting CONSTRUCTOR
> trees emitted for array initializers like the above to STRING_CST
> (see bug 71625 for some background). I think that would still be
> the ideal solution. Then you wouldn't have to change
> get_range_strlen.
thanks for the info, Martin.
In my case, it’s the size of “100” cannot be collected in the MINMAXLEN[1] for
the string “s”.
I need to make sure that the size of variable string s is larger than the size
of constant string “abc” to guarantee the safety of the transformation.
currently, “get_range_strlen” cannot identify the simple VAR_DECL with
array_type to determine the maximum size of the string.
Qing
>
> Martin
