Per mailing list instructions and using a branch checkout from today,

../gimple-tuples-branch/configure --disable-libgomp --disable-libmudflap
make

on Darwin fails with an illegal instruction:

/Users/shebs/s/gcc/tuples/macosx/./prev-gcc/xgcc -B/Users/shebs/s/gcc/tuples/macosx/./prev-gcc/ -B/usr/local/i386-apple-darwin9.2.2/bin/ -c  -g -O2 -fomit-frame-pointer -DIN_GCC   -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition -Wmissing-format-attribute -pedantic -Wno-long-long -Wno-variadic-macros 				     -Wno-overlength-strings -Werror -Werror -Wno-return-type -fno-common  -DHAVE_CONFIG_H -I. -I. -I../../gimple-tuples-branch/gcc -I../../gimple-tuples-branch/gcc/. -I../../gimple-tuples-branch/gcc/../include -I./../intl -I../../gimple-tuples-branch/gcc/../libcpp/include  -I../../gimple-tuples-branch/gcc/../libdecnumber -I../../gimple-tuples-branch/gcc/../libdecnumber/dpd -I../libdecnumber  insn-attrtab.c -o insn-attrtab.o
xgcc: Internal error: Illegal instruction (program cc1)
Please submit a full bug report.
See <http://gcc.gnu.org/bugs.html> for instructions.
make[3]: *** [insn-attrtab.o] Error 1
make[2]: *** [all-stage3-gcc] Error 2
make[1]: *** [stage3-bubble] Error 2
make: *** [all] Error 2