Re: [Valgrind-users] helgrind and stlport

[Vojtech F. <voj...@se...>]

> Vectors are special: I'm not sure "_STLP_USE_NEWALLOC" catches
> vector<> resizing. Consider e.g. the following code:
> 
> struct C { int i; };
> int main()
> {
>   std::vector<C> V;
>   V.resize(2);
>   V[1].i = 1;
>   V.resize(1);
>   V.resize(2);
>   printf("V[1].i = %d\n", V[1].i);
>   return 0;
> }
> 
> Since std::vector<> does not reallocate the vector when resizing it
> from two to one elements, memcheck doesn't complain that the value
> read by the printf() call is undefined.
> 
> Bart.

You are right. It is more tricky than I thought.
But if the vector is accessed only from one thread it should not be a problem
for helgrind.
Probably helgrind does not see that the memory the vector occupies is eventually
deleted or STLPort recycles memory even with "new_alloc".
I don't know. I will have to investigate it further. 

Vojtech