From 6994ea0046784f0f70f167c131720697c104ccca Mon Sep 17 00:00:00 2001
From: Danila Fedorin <danila.fedorin@gmail.com>
Date: Sun, 6 Dec 2020 17:40:52 -0800
Subject: [PATCH] Fix segmentation fault.

---
 bpred.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/bpred.c b/bpred.c
index d41f827..62969cc 100644
--- a/bpred.c
+++ b/bpred.c
@@ -966,7 +966,9 @@ bpred_update(struct bpred_t *pred,	/* branch predictor instance */
   /* update state (but not for jumps) */
   if (dir_update_ptr->pdir1)
     {
-      char pred_cutoff = (pred->dirpred.bimod->class == BPred3bit) ? 7 : 3;
+      struct bpred_dir_t* p1 =
+          pred->dirpred.bimod ? pred->dirpred.bimod : pred->dirpred.twolev;
+      char pred_cutoff = (p1->class == BPred3bit) ? 7 : 3;
       if (taken)
 	{
 	  if (*dir_update_ptr->pdir1 < pred_cutoff)
@@ -983,6 +985,7 @@ bpred_update(struct bpred_t *pred,	/* branch predictor instance */
   /* second direction predictor */
   if (dir_update_ptr->pdir2)
     {
+      /* Assumption: second predictor is always two-level. */
       char pred_cutoff = (pred->dirpred.twolev->class == BPred3bit) ? 7 : 3;
       if (taken)
 	{