[Bug bootstrap/59528] New: Profiledbootstrap should use stage1 compiler during stagefeedback

[hubicka at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59528

            Bug ID: 59528
           Summary: Profiledbootstrap should use stage1 compiler during
                    stagefeedback
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: bootstrap
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hubicka at gcc dot gnu.org

I just noticed that recently profiledbootstrap uses stageprofile compiler to
build final binary (i.e. one with instrumentation in). This is not only
wasteful for CPU time, but more importantly will lead to different binary each
time during parallel compilation - at compiling object file X during final
compilation the profile depends on compilation of all before.

We used to rebuild using stage1 compiler for this reason - that is
 1) build stage1 compiler
 2) build stage profile compiler + runtime library that also serves as a train
run
 3) build stage feedback compiler using data stage1 compiler with profile data
collected at 2)