Regressions on trunk at revision 175318 vs revision 175306

[H.J. Lu ia32]

New failures:

New passes:
FAIL: g++.dg/torture/pr43879-1_1.C  -O1  execution test
FAIL: g++.dg/torture/pr43879-1_1.C  -O2  execution test
FAIL: g++.dg/torture/pr43879-1_1.C  -O3 -fomit-frame-pointer  execution test
FAIL: g++.dg/torture/pr43879-1_1.C  -O3 -g  execution test
FAIL: g++.dg/torture/pr43879-1_1.C  -Os  execution test