Bug 28030

The following code only gets vectorized with explicitly copying the "size_" member to the local "sz" variable for 4.1.1, 4.2.0 rev. 114610 and autovect branch.

=========================================
template <class T>
class vec 
{
public:
  vec& multiply(const vec& other)
    {
      // do something to make sure restrict is valid...

      const T* __restrict__ op = other.data_;
      T* __restrict__ tp = data_;
      
      unsigned int sz = size_; // NEEDED!
      
      for (unsigned int i=0; i<sz; ++i) {
        tp[i] *= op[i];
      }
      return *this;
    }

private:
  unsigned int size_;
  T* data_;
};

template class vec<int>;
=========================================

Without the local variable I get the following output:

g++ -O3 -ftree-vectorize -ftree-vectorizer-verbose=7 -march=pentium-m -c vectorizer.cpp

vectorizer.cpp:16: note: ===== analyze_loop_nest =====
vectorizer.cpp:16: note: === vect_analyze_loop_form ===
vectorizer.cpp:16: note: split exit edge.
vectorizer.cpp:16: note: === get_loop_niters ===
vectorizer.cpp:16: note: not vectorized: number of iterations cannot be computed.
vectorizer.cpp:16: note: bad loop form.
vectorizer.cpp:16: note: vectorized 0 loops in function.
--------------------------------------------------------------------

It works fine for T in [float, double, long int] 

Using
typedef int aint __attribute__ ((__aligned__(16)));
as in the examples doesn't help.

Replacing the template declaration with int and using the class in main() leads to vectorization of the loop without needing the local variable.