[Bug bootstrap/58509] [4.9 regression] ICE in calc_dfs_tree, at dominance.c:397 breaks Ada bootstrap on sparc64-linux

["mikpe at it dot uu.se" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58509

--- Comment #2 from Mikael Pettersson <mikpe at it dot uu.se> ---
(gdb) break fancy_abort
Breakpoint 2 at 0x9e4a04
(gdb) run -gnatwa -quiet -nostdinc -dumpbase g-awk.adb -auxbase-strip g-awk.o
-O2 -Wextra -Wall -fPIC -g -gnatpg -mcpu=ultrasparc -gnatO g-awk.o g-awk.adb -o
/tmp/ccUyexwj.s
Starting program: /mnt/scratch/objdir49/gcc/gnat1 -gnatwa -quiet -nostdinc
-dumpbase g-awk.adb -auxbase-strip g-awk.o -O2 -Wextra -Wall -fPIC -g -gnatpg
-mcpu=ultrasparc -gnatO g-awk.o g-awk.adb -o /tmp/ccUyexwj.s

Breakpoint 2, 0x009e4a04 in fancy_abort(char const*, int, char const*) ()
(gdb) bt
#0  0x009e4a04 in fancy_abort(char const*, int, char const*) ()
#1  0x00409bbc in calc_dfs_tree(dom_info*, bool) () at
/mnt/scratch/gcc-4.9-20130922/gcc/dominance.c:397
#2  0x0040a234 in calculate_dominance_info(cdi_direction) () at
/mnt/scratch/gcc-4.9-20130922/gcc/dominance.c:658
#3  0x003be1f4 in flow_loops_find(loops*) ()
#4  0x00570630 in loop_optimizer_init(unsigned int) () at
/mnt/scratch/gcc-4.9-20130922/gcc/loop-init.c:91
#5  0x00965c30 in if_convert(bool) () at
/mnt/scratch/gcc-4.9-20130922/gcc/ifcvt.c:4377
#6  0x009676b0 in (anonymous namespace)::pass_if_after_reload::execute() () at
/mnt/scratch/gcc-4.9-20130922/gcc/ifcvt.c:4587
#7  0x005d9ef4 in execute_one_pass(opt_pass*) () at
/mnt/scratch/gcc-4.9-20130922/gcc/passes.c:2201
#8  0x005da13c in execute_pass_list(opt_pass*) () at
/mnt/scratch/gcc-4.9-20130922/gcc/passes.c:2253
#9  0x005da160 in execute_pass_list(opt_pass*) () at
/mnt/scratch/gcc-4.9-20130922/gcc/passes.c:2254
#10 0x005da160 in execute_pass_list(opt_pass*) () at
/mnt/scratch/gcc-4.9-20130922/gcc/passes.c:2254
#11 0x003d98f4 in expand_function(cgraph_node*) () at
/mnt/scratch/gcc-4.9-20130922/gcc/cgraphunit.c:1750
#12 0x003db730 in compile() () at
/mnt/scratch/gcc-4.9-20130922/gcc/cgraphunit.c:1855
#13 0x003dbb80 in finalize_compilation_unit() () at
/mnt/scratch/gcc-4.9-20130922/gcc/cgraphunit.c:2269
#14 0x0006bcbc in gnat_write_global_declarations() () at
/mnt/scratch/gcc-4.9-20130922/gcc/ada/gcc-interface/utils.c:5630
#15 0x00692200 in compile_file() ()
#16 0x006940bc in toplev_main(int, char**) ()
#17 0xf7d44234 in __libc_start_main () from /lib/libc.so.6
#18 0x00044054 in _start ()
(gdb)