Fix null pointer dereference after failing to extract DFF from memory.

Fixes #3110.

diff --git a/kernel/mem.cc b/kernel/mem.cc
index 746f667ea77f6333d3edec14c127a0ef88768718..96168ff76b3949aae086b7c8f353a1bd471197ff 100644 (file)
--- a/kernel/mem.cc
+++ b/kernel/mem.cc
@@ -985,7 +985,8 @@ Cell *Mem::extract_rdff(int idx, FfInitVals *initvals) {
                c = ff.emit();
        }
 
-       log("Extracted %s FF from read port %d of %s.%s: %s\n", trans_use_addr ? "addr" : "data",
+       if (c)
+               log("Extracted %s FF from read port %d of %s.%s: %s\n", trans_use_addr ? "addr" : "data",
                        idx, log_id(module), log_id(memid), log_id(c));
 
        port.en = State::S1;