bootstrap failure on ia64-linux building libgcc

[Janis Johnson <janis at us dot ibm dot com>]

A bootstrap or simple native build of C on ia64-unknown-linux, or an
ia64 cross build from i686-pc-linux-gnu, fails when compiling libgcc2.c:

./xgcc -B./ -B/home/janis/gnu/tools/ia64-unknown-linux/bin/ -isystem /home/janis/gnu/tools/ia64-unknown-linux/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-mainline/gcc -I../../gcc-mainline/gcc/. -I../../gcc-mainline/gcc/config -I../../gcc-mainline/gcc/../include -DL_fixdfdi -c ../../gcc-mainline/gcc/libgcc2.c -o libgcc/./_fixdfdi.o
cc1: warning: changing search order for system directory "include"
cc1: warning:   as it has already been specified as a system directory
cc1: warning: changing search order for system directory "/home/janis/gnu/tools/ia64-unknown-linux/include"
cc1: warning:   as it has already been specified as a system directory
../../gcc-mainline/gcc/libgcc2.c: In function `__fixdfti':
../../gcc-mainline/gcc/libgcc2.c:958: Internal compiler error in propagate_one_insn, at flow.c:4885
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://www.gnu.org/software/gcc/bugs.html> for instructions.

According to the comments in flow.c the abort happens for "trying to
delete a prologue or epilogue instruction that isn't flagged as possibly
being dead."

Janis