Regressions on trunk at revision 227303 vs revision 227297

[H.J. Lu Intel64 Core i7]

New failures:
FAIL: gcc.dg/guality/pr54970.c   -Os  line 15 a[0] == 1
FAIL: gcc.dg/guality/pr54970.c   -Os  line 20 a[0] == 1
FAIL: gcc.dg/guality/pr54970.c   -Os  line 25 a[0] == 1
FAIL: gcc.dg/guality/pr54970.c   -Os  line 31 a[0] == 4
FAIL: gcc.dg/guality/pr54970.c   -Os  line 36 a[0] == 4
FAIL: gcc.dg/guality/pr54970.c   -Os  line 45 a[0] == 4
FAIL: gcc.dg/guality/pr54970.c   -Os  line 45 p[-2] == 4
FAIL: gcc.dg/guality/pr54970.c   -Os  line 45 q[-1] == 4

New passes:
FAIL: g++.dg/torture/pr64312.C   -O1  (test for excess errors)