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ae4e1a94e3
If an outside loop user of the reduction value uses the header phi node we cannot just reduce the vectorized phi value in the vector code epilog because we would loose VF-1 reductions. lp: p = phi (0, lv) lv = lv + 1 ... brcond , lp, outside outside: usr = add 0, p (Say the loop iterates two times, the value of p coming out of the loop is one). We cannot just transform this to: vlp: p = phi (<0,0>, lv) lv = lv + <1,1> .. brcond , lp, outside outside: p_reduced = p[0] + [1]; usr = add 0, p_reduced (Because the original loop iterated two times the vectorized loop would iterate one time, but p_reduced ends up being zero instead of one). We would have to execute VF-1 iterations in the scalar remainder loop in such cases. For now, just disable vectorization. PR16522 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@186256 91177308-0d34-0410-b5e6-96231b3b80d8