Regressions on trunk at revision 234915 vs revision 234894

[Intel Automatic Testing System [Intel64 Core AVX2 PIC]]

New failures:

New passes:
FAIL: gcc.dg/tree-ssa/cunroll-10.c scan-tree-dump-times cunroll "Forced statement unreachable" 2
FAIL: gcc.dg/tree-ssa/prefetch-5.c scan-tree-dump-times aprefetch "Issued prefetch" 2
FAIL: gcc.dg/tree-ssa/prefetch-5.c scan-tree-dump-times aprefetch "Not prefetching" 1