mem: Check response only when needed in CommMonitor

CommMonitor checks pkt->isResponse() for all packets in recvAtomic().
This assertion fails when packets don't need response, such as WritebackDirty.
This change fixes this.

Signed-off-by: Chun-Chen TK Hsu
Change-Id: I168e349e179b14fa5472698d9300478dc89693fb
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19428
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Maintainer: Nikos Nikoleris <nikos.nikoleris@arm.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/mem/comm_monitor.cc

@@ -220,7 +220,8 @@ CommMonitor::recvAtomic(PacketPtr pkt)
     if (expects_response)
         stats.updateRespStats(req_pkt_info, delay, true);
 
-    assert(pkt->isResponse());
+    // Some packets, such as WritebackDirty, don't need response.
+    assert(pkt->isResponse() || !expects_response);
     ProbePoints::PacketInfo resp_pkt_info(pkt);
     ppPktResp->notify(resp_pkt_info);
     return delay;