[Bug debug/47684] New: -fcompare-debug failure with -O3

[zsojka at seznam dot cz]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47684

           Summary: -fcompare-debug failure with -O3
           Product: gcc
           Version: 4.6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: debug
        AssignedTo: unassig...@gcc.gnu.org
        ReportedBy: zso...@seznam.cz
                CC: aol...@gcc.gnu.org
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 23297
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=23297
reduced testcase

Compiler output:
$ gcc -O3 -fcompare-debug testcase.c
gcc: error: testcase.c: -fcompare-debug failure (length)

The generated code is very different with/without debug.

Tested revisions:
r169997 - fail
4.5 r168785 - fail