Currently, LLVM supports vectorization of horizontal reduction instructions with initial value set to 0. Patch supports vectorization of reduction with non-zero initial values. Also, it supports a vectorization of instructions with some extra arguments, like:
float f(float x[], int a, int b) { float p = a % b; p += x[0] + 3; for (int i = 1; i < 32; i++) p += x[i]; return p; }
Patch allows vectorization of this kind of horizontal reductions.