[otbn,dv] Don't write to const registers with BN.LID in RIG
This hasn't come up until now because we didn't have any way to get
known register values (and, hence, const registers). However, Canberk
is working on a snippet generator that makes some and turning up quite
a few of these bugs.
Signed-off-by: Rupert Swarbrick <rswarbrick@lowrisc.org>
diff --git a/hw/ip/otbn/dv/rig/rig/gens/straight_line_insn.py b/hw/ip/otbn/dv/rig/rig/gens/straight_line_insn.py
index 4a1de07..10b94f9 100644
--- a/hw/ip/otbn/dv/rig/rig/gens/straight_line_insn.py
+++ b/hw/ip/otbn/dv/rig/rig/gens/straight_line_insn.py
@@ -183,8 +183,10 @@
Here, the GPR value must be known and must be at most 31. If wdr_is_src
then the WDR that it points to must also have an architectural value.
+ Otherwise, the WDR is a destination and must not be marked const.
'''
+ wdr_is_dest = not wdr_is_src
arch_wdrs = set(model.regs_with_architectural_vals('wdr'))
valid_gprs = []
for gpr, gpr_val in known_regs:
@@ -192,6 +194,8 @@
continue
if wdr_is_src and gpr_val not in arch_wdrs:
continue
+ if wdr_is_dest and model.is_const('wdr', gpr_val):
+ continue
valid_gprs.append(gpr)
