Regressions on trunk at revision 159557 vs revision 159555

[H.J. Lu Intel64]

New failures:
FAIL: gcc.dg/tree-ssa/prefetch-3.c scan-tree-dump-times aprefetch "unroll factor 4" 1
FAIL: gcc.dg/tree-ssa/prefetch-5.c scan-tree-dump-times aprefetch "Issued prefetch" 2
FAIL: gcc.dg/tree-ssa/prefetch-6.c scan-assembler-times prefetchnta 3
FAIL: gcc.dg/tree-ssa/prefetch-6.c scan-tree-dump-times aprefetch "Issued nontemporal prefetch" 3
FAIL: gcc.dg/tree-ssa/update-unroll-1.c scan-tree-dump-not aprefetch "SUCC: 7 .100.0%"

New passes: