[Bug tree-optimization/50764] New: [4.7 Regression] ICE: in maybe_record_trace_start, at dwarf2cfi.c:2243 with -O2 -fsched2-use-superblocks -ftree-tail-merge

["zsojka at seznam dot cz" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50764

             Bug #: 50764
           Summary: [4.7 Regression] ICE: in maybe_record_trace_start, at
                    dwarf2cfi.c:2243 with -O2 -fsched2-use-superblocks
                    -ftree-tail-merge
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: zsojka@seznam.cz
                CC: vries@gcc.gnu.org
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu


Created attachment 25528
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=25528
reduced testcase

Compiler output:
$ gcc -O2 -fsched2-use-superblocks testcase.c
testcase.c: In function 'foo':
testcase.c:13:1: internal compiler error: in maybe_record_trace_start, at
dwarf2cfi.c:2243
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://gcc.gnu.org/bugs.html> for instructions.

Maybe related to -ftree-tail-merge, as it doesn't crash with
-fno-tree-tail-merge.

Tested revisions:
r180072 - crash
r179959 - crash
r178498 - OK
4.6 r177922 - OK