Issues with compiler failures

[John Klos <john%ziaspace.com@localhost>]

We've had a number of issues with gcc 5.5.0, such as the following which 
happens when compiling pkgtools/digest:

gcc -DHAVE_CONFIG_H -I. -I. -DHOST=\"vax--netbsdelf\" 
-DVERSION=\"20180917\" -O -D_FORTIFY_SOURCE=2 -c blake2b.c -o blake2b.o

blake2b.c: In function 'blake2b_compress':
blake2b.c:171:1: internal compiler error: in cselib_invalidate_regno, at 
cselib.c:2169
 }
 ^
no stack trace because unwind library not available
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://www.NetBSD.org/support/send-pr.html> for instructions.

-O2 doesn't work, nor does -O, nor does -Os. It takes -O0


Likewise, in net/rsync:

gcc -I. -I. -I./zlib -I./popt -O2 -D_FORTIFY_SOURCE=2 -I/usr/include 
-DHAVE_CONFIG_H -Wall -W -I/usr/include -c checksum.c -o checksum.o
checksum.c: In function 'get_checksum2':
checksum.c:191:1: internal compiler error: in change_address_1, at 
emit-rtl.c:2125
 }
 ^
no stack trace because unwind library not available
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://www.NetBSD.org/support/send-pr.html> for instructions.
*** Error code 1

Using -O0 fixes this, too.

Does anyone know how to fix this properly?

John