[Bug middle-end/51521] New: [4.7 Regression]: build fails on cris-elf building libstdc++-v3: verify_flow_info failed

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=51521

             Bug #: 51521
           Summary: [4.7 Regression]: build fails on cris-elf building
                    libstdc++-v3: verify_flow_info failed
    Classification: Unclassified
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Keywords: build, ice-on-valid-code
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: hp@gcc.gnu.org
                CC: dvyukov@gcc.gnu.org
              Host: x86_64-unknown-linux-gnu
            Target: cris-axis-elf


Created attachment 26065
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=26065
Repeat with cc1plus -fpreprocessed strstream.ii -O2

A patch in the revision range (last_known_working:first_known_failing)
r182243:182256 caused the build for cris-elf to fail as follows:

libtool: compile:  /tmp/hpautotest-gcc1/cris-elf/gccobj/./gcc/xgcc
-shared-libgcc -B/tmp/hpautotest-gcc1/cris-elf/gccobj/./gcc -nostdinc++
-L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/src
-L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/src/.libs
-nostdinc -B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/newlib/ -isystem
/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/newlib/targ-include -isystem
/tmp/hpautotest-gcc1/gcc/newlib/libc/include
-B/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libgloss/cris
-L/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libgloss/libnosys
-L/tmp/hpautotest-gcc1/gcc/libgloss/cris
-B/tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/bin/
-B/tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/lib/ -isystem
/tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/include -isystem
/tmp/hpautotest-gcc1/cris-elf/pre/cris-elf/sys-include
-I/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/cris-elf
-I/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include
-I/tmp/hpautotest-gcc1/gcc/libstdc++-v3/libsupc++ -fno-implicit-templates -Wall
-Wextra -Wwrite-strings -Wcast-qual -fdiagnostics-show-location=once
-ffunction-sections -fdata-sections -frandom-seed=strstream.lo -g -O2
-I/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/backward
-Wno-deprecated -c /tmp/hpautotest-gcc1/gcc/libstdc++-v3/src/strstream.cc -o
strstream.o
In file included from
/tmp/hpautotest-gcc1/gcc/libstdc++-v3/src/strstream.cc:45:0:
/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/backward/strstream:
In member function 'void std::istrstream::_ZTv0_n12_NSt10istrstreamD0Ev()':
/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/backward/strstream:134:13:
error: fallthru to exit from bb 2
/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/backward/strstream:134:13:
error: fallthru edge after a control statement in bb 2
/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/backward/strstream:134:13:
error: wrong outgoing edge flags at end of bb 2
/tmp/hpautotest-gcc1/cris-elf/gccobj/cris-elf/libstdc++-v3/include/backward/strstream:134:13:
internal compiler error: verify_flow_info failed

Author of the most suspect patch in the revision range (to gcc/cgraphunit.c,
r182248) CC:ed and preprocessed strstream.ii attached.