Backport r180979 from branches/google/gcc-4_6. (issue 5501051)

[asharif@google.com]

Reviewers: xur, bjanakiraman_google.com, jingyu,

Message:
Please review this backport.



Please review this at http://codereview.appspot.com/5501051/

Affected files:
    M    gcc-4_6-mobile
   M     gcc-4_6-mobile/gcc/ChangeLog.google-4_6
   M     gcc-4_6-mobile/gcc/common.opt
   M     gcc-4_6-mobile/gcc/coverage.c
   M     gcc-4_6-mobile/gcc/flag-types.h
   M     gcc-4_6-mobile/gcc/mcf.c
   M     gcc-4_6-mobile/gcc/opts.c
   M     gcc-4_6-mobile/gcc/profile.c
   M     gcc-4_6-mobile/gcc/testsuite/g++.dg/tree-ssa/dom-invalid.C
   M     gcc-4_6-mobile/gcc/testsuite/gcc.dg/pr26570.c
   M     gcc-4_6-mobile/gcc/testsuite/gcc.dg/pr32773.c
   M     gcc-4_6-mobile/gcc/testsuite/gcc.dg/pr40209.c
   M     gcc-4_6-mobile/gcc/tree-profile.c
   M     gcc-4_6-mobile/gcc/value-prof.c