commit fda07590df36d0b9bad690e8e6c5fbbd40a809c6
author Kaustav Goswami <kggoswami@ucdavis.edu> Mon Apr 25 18:19:18 2022 -0700
committer Kaustav Goswami <kggoswami@ucdavis.edu> Thu Apr 28 16:57:59 2022 +0000
tree 729bb78e2a29cbd8d2142a7ad83c7b8f39d8de8d
parent f8589a4719b6f506e40badd32afc5cc5046183a1

cpu: nullptr in a DPRINTF statement

This change fixes the crashing of gem5 when `Branch` debug flag
is enabled. A DPRINTF statement had a nullptr. This change
prints `INVALID_TARGET` if the nullptr is encountered.

Signed-off-by: Kaustav Goswami <kggoswami@ucdavis.edu>
Change-Id: I40bd42c07de25a493a3dd1094a2fd8cc0ce0a79b
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/59109
Tested-by: kokoro <noreply+kokoro@google.com>
Reviewed-by: Jason Lowe-Power <power.jg@gmail.com>
Maintainer: Jason Lowe-Power <power.jg@gmail.com>

src/cpu/pred/bpred_unit.cc

diff --git a/src/cpu/pred/bpred_unit.cc b/src/cpu/pred/bpred_unit.cc
index 0940ae1..ac51567 100644
--- a/src/cpu/pred/bpred_unit.cc
+++ b/src/cpu/pred/bpred_unit.cc
@@ -335,10 +335,19 @@
     while (!pred_hist.empty() &&
            pred_hist.front().seqNum > squashed_sn) {
         if (pred_hist.front().usedRAS) {
-            DPRINTF(Branch, "[tid:%i] [squash sn:%llu]"
-                    " Restoring top of RAS to: %i,"
-                    " target: %s\n", tid, squashed_sn,
-                    pred_hist.front().RASIndex, *pred_hist.front().RASTarget);
+            if (pred_hist.front().RASTarget != nullptr) {
+                DPRINTF(Branch, "[tid:%i] [squash sn:%llu]"
+                        " Restoring top of RAS to: %i,"
+                        " target: %s\n", tid, squashed_sn,
+                        pred_hist.front().RASIndex,
+                        *pred_hist.front().RASTarget);
+            }
+            else {
+                DPRINTF(Branch, "[tid:%i] [squash sn:%llu]"
+                        " Restoring top of RAS to: %i,"
+                        " target: INVALID_TARGET\n", tid, squashed_sn,
+                        pred_hist.front().RASIndex);
+            }
 
             RAS[tid].restore(pred_hist.front().RASIndex,
                              pred_hist.front().RASTarget.get());