From 9cadc8ddfd0b4597daab0bceb6a80cdac4cfffb4 Mon Sep 17 00:00:00 2001
From: Brian Demsky <bdemsky@uci.edu>
Date: Mon, 1 Oct 2012 21:48:34 -0700
Subject: [PATCH] Two change: (1) Bug fix...  Check that rf is non-null before
 calling r_modification

(2) Add a hook into assert mechanism for the debugger
---
 common.cc | 5 +++++
 common.h  | 4 +++-
 model.cc  | 3 ++-
 3 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/common.cc b/common.cc
index ac5cb596..e05e094e 100644
--- a/common.cc
+++ b/common.cc
@@ -29,3 +29,8 @@ void model_print_summary(void)
 {
 	model->print_summary();
 }
+
+void assert_hook(void)
+{
+	printf("Add breakpoint to line %u in file %s.\n",__LINE__,__FILE__);
+}
diff --git a/common.h b/common.h
index 2dc8b7d9..003dc805 100644
--- a/common.h
+++ b/common.h
@@ -18,12 +18,15 @@
 #define DBG_ENABLED() (0)
 #endif
 
+void assert_hook(void);
+
 #define ASSERT(expr) \
 do { \
 	if (!(expr)) { \
 		fprintf(stderr, "Error: assertion failed in %s at line %d\n", __FILE__, __LINE__); \
 		print_trace(); \
 		model_print_summary(); \
+		assert_hook();				 \
 		exit(EXIT_FAILURE); \
 	} \
 } while (0);
@@ -32,5 +35,4 @@ do { \
 
 void print_trace(void);
 void model_print_summary(void);
-
 #endif /* __COMMON_H__ */
diff --git a/model.cc b/model.cc
index 9dc1d37c..a22e0214 100644
--- a/model.cc
+++ b/model.cc
@@ -658,7 +658,8 @@ Thread * ModelChecker::check_current_action(ModelAction *curr)
 			bool updated = false;
 
 			if (act->is_read()) {
-				if (r_modification_order(act, act->get_reads_from()))
+				const ModelAction *rf = act->get_reads_from();
+				if (rf != NULL && r_modification_order(act, rf))
 					updated = true;
 			}
 			if (act->is_write()) {
-- 
2.34.1