see comment on mailing list: http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2020-July/008637.html

yep, that's down to changing of a "hack" function which is now
no longer appropriate

diff --git a/src/soc/decoder/pseudo/parser.py b/src/soc/decoder/pseudo/parser.py
index 346e3f98..3d75fbb0 100644
--- a/src/soc/decoder/pseudo/parser.py
+++ b/src/soc/decoder/pseudo/parser.py
@@ -615,7 +615,8 @@ class PowerParser:
                 l, r = p[1], p[3]
                 # actual call will be "dividend / divisor" - just check
                 # LHS name
-                if isinstance(l, ast.Name) and l.id == 'dividend':
+                # XXX DISABLE BAD HACK (False)
+                if False and isinstance(l, ast.Name) and l.id == 'dividend':
                     if p[2] == '/':
                         fn = 'trunc_divs'
                     else:

this is related to that helper function that you wrote (which is great btw).
it turns out that it's a signed (only) floor_div function, and that
calling "standard" (python3) floordiv is appropriate in unsigned cases
(such as divwuo)

i had messed up the parser and called the wrong function since changing
the pseudo-code to actually *explicitly* call DIVS:

http://lists.mailinglist.openpowerfoundation.org/pipermail/openpower-hdl-cores/2020-July/000078.html