https://gcc.gnu.org/bugzilla/show_bug.cgi?id=19852
--- Comment #6 from yjf.victor at foxmail dot com ---
According to my debugging on gdb, it failed to allocate the memory via the
`alloca()` function, and therefore resulted in Segmentation fault.
```
% gdb build/genmodes
GNU gdb 2002-11-11-cvs
Copyright 2002 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB. Type "show warranty" for details.
This GDB was configured as "i586-pc-interix3"...
.gdbinit:13: Error in sourced command file:
/dev/fs/E/22/gcc/gcc-5.5.0/gcc/gdbinit.in:212: Error in sourced command file:
Command not implemented yet.
(gdb) b genmodes.c:851
Breakpoint 1 at 0x403899: file /dev/fs/E/22/gcc/gcc-5.5.0/gcc/genmodes.c, line
8
51.
(gdb) r -h
Starting program: /dev/fs/E/22/gcc/bindir/gcc/build/genmodes -h
Breakpoint 1, _Z15calc_wider_modev ()
at /dev/fs/E/22/gcc/gcc-5.5.0/gcc/genmodes.c:851
851 sortbuf = XALLOCAVEC (struct mode_data *, max_n_modes + 1);
(gdb) n
Program received signal SIGSEGV, Segmentation fault.
0x0083ff7a in ?? ()
(gdb)
```
