Regressions on trunk at revision 263906 vs revision 263871

[H.J. Lu (Intel64 Core i7)]

New failures:
FAIL: gcc.dg/guality/pr41447-1.c   -O2 -flto -fuse-linker-plugin -fno-fat-lto-objects  -DPREVENT_OPTIMIZATION execution test

New passes:
FAIL: gcc.c-torture/execute/builtins/strnlen.c compilation,  -O1  (internal compiler error)
FAIL: gcc.c-torture/execute/builtins/strnlen.c compilation,  -O1  (internal compiler error)
FAIL: gcc.c-torture/execute/builtins/strnlen.c compilation,  -Og -g  (internal compiler error)
FAIL: gcc.c-torture/execute/builtins/strnlen.c compilation,  -Og -g  (internal compiler error)
FAIL: gcc.c-torture/execute/builtins/strnlen.c compilation,  -Os  (internal compiler error)
FAIL: gcc.c-torture/execute/builtins/strnlen.c compilation,  -Os  (internal compiler error)