[Bug gcov-profile/51975] New: ICE in gcc in convert_move, at expr.c:326 with fprofile-use when source changes from fprofile-generate

["asharif at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51975

             Bug #: 51975
           Summary: ICE in gcc in convert_move, at expr.c:326 with
                    fprofile-use when source changes from
                    fprofile-generate
    Classification: Unclassified
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: gcov-profile
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: asharif@gcc.gnu.org


Created attachment 26438
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26438
Tarball containing the test files and the proposed fix.

Please see attached testcase, which fails with gcc-4.6.0:

gcc -o profile_io_data.o profile_io_data.ii -O2 -Wno-error -fpermissive
-fprofile-use -m32 -c

This happens because the profile .gcda file is oudated compared to the current
source. gcc's assignment of function ids on the current source is different
from the assignment when it did fprofile-generate. This causes an ICE later
down the pipeline.

I am also attaching a proposed fix, which builds a hash table of function ids
-> cfg checksums when reading in the profile files. At profile use time, in
check_ic_target(), gcc makes sure the target function's checksum matches the
checksum that is found in the gcda file.