verify_flow_info check fails building libgcc2 on ia64

[Janis Johnson]

The mainline bootstrap of ia64-unknown-linux-gnu has been failing for
awhile now for various reasons, but currently it fails with a check in
verify_flow_info building libgcc2:

./xgcc -B./ -B/home/build/gcc_mainline/ia64/install/ia64-unknown-linux/bin/ -isystem /home/build/gcc_mainline/ia64/install/ia64-unknown-linux/include -isystem /home/build/gcc_mainline/ia64/install/ia64-unknown-linux/sys-include -O2  -DIN_GCC    -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -isystem ./include  -fPIC -g1  -DIN_LIBGCC2 -D__GCC_FLOAT_NOT_NEEDED  -I. -I. -I../../../gcc/gcc -I../../../gcc/gcc/. -I../../../gcc/gcc/config -I../../../gcc/gcc/../include  -DL_lshrdi3 -c ../../../gcc/gcc/libgcc2.c -o libgcc/./_lshrdi3.o
../../../gcc/gcc/libgcc2.c: In function `__lshrti3':
../../../gcc/gcc/libgcc2.c:266: verify_flow_info: REG_BR_PROB does not match cfg 5000 0
../../../gcc/gcc/libgcc2.c:266: verify_flow_info failed
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions

I've seen messages about problems with verify_flow_info building libjava
but haven't seen anything about this failure.  Honza, let me know if
you'd like more information about this.

Janis