Regressions on trunk at revision 247721 vs revision 247720

[H.J. Lu ia32 -fpic]

New failures:
FAIL: gcc.dg/tree-ssa/ssa-dom-thread-4.c scan-tree-dump-times dom2 "Threaded" 2
FAIL: gcc.dg/tree-ssa/ssa-dom-thread-4.c scan-tree-dump-times vrp1 "Threaded" 2
FAIL: gcc.dg/tree-ssa/ssa-thread-17.c scan-tree-dump-times vrp1 "Folded into:[^\r\n]*ASSERT_EXPR*[^\r\n]* == 1" 1
FAIL: gcc.dg/tree-ssa/ssa-thread-17.c scan-tree-dump-times vrp1 "Threaded" 1

New passes: