[Bug middle-end/43182] GCC does not pull out a[0] from loop that changes a[i] for i:[1,n]

[changpeng dot fang at amd dot com]

------- Comment #4 from changpeng dot fang at amd dot com  2010-02-26 18:53 -------
Here is another similar case but more general. We know that a(j) and a(i)
never access the same memory location. intel ifort can vectorize this
triangular
loop:

      do 10 j = 1,n
         do 20 i = j+1, n
            a(i) = a(i) - aa(i,j) * a(j)
  20     continue
  10  continue


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43182