[cilksan] Add two more rr commands for navigating to races from the c…

…urrent point during replay. These commands allow users to, for example, navigate to an arbitrary breakpoint, and then navigate to the nearest race before or after that breakpoint.

cilksan/rr_commands.py

@@ -35,7 +35,7 @@ class CilksanPrefixCommand(gdb.Command):
 For navigating between races, these commands maintain a current race
 target, which consists of:
 - the current race I,
-- the current racing pair (I, J) where J is among the racers of I, and
+- the current racing pair (I, J), where J is among the racers of I, and
 - an endpoint in that pair.
 Navigation commands can operate relative to the current race target
 and update that target.  The command `cilksan race-info` prints
@@ -266,6 +266,100 @@ def invoke(self, arg, from_tty):
 
 PrevRaceCommand()
 
+class FFToRaceCommand(gdb.Command):
+    """Fast-forward program execution to the next race after this time.
+
+Usage: cilksan ff-to-race
+
+Seek to the next determinacy race after the current point in the replay.
+Update the current race target."""
+
+    def __init__(self):
+        super(FFToRaceCommand, self).__init__('cilksan ff-to-race',
+                                              gdb.COMMAND_RUNNING,
+                                              gdb.COMPLETE_NONE, False)
+
+    def invoke(self, arg, from_tty):
+        if len(races) == 0:
+            print(no_races_error_msg)
+            return
+        # Get the current user time
+        when_user_time = gdb.execute('when-user-time', False, True)
+        parse = re.search("Current\s+user\s+time:\s+(-?\d+)", when_user_time)
+        current_user_time = int(parse.group(1))
+
+        # Binary search for the next race after the current user time
+        start = 0
+        end = len(races)
+        while end - start > 1:
+            mid = start + ((end - start) // 2)
+            next_race_time = time_for_race(mid)
+            if next_race_time <= current_user_time:
+                start = mid
+            else:
+                end = mid
+        if time_for_race(start) <= current_user_time:
+            start = start + 1
+        if start >= len(races):
+            print("No races after this point in the replay.")
+            return
+
+        # Seek to the race
+        next_race_time = time_for_race(start)
+        current_race[0] = start
+        current_race[1] = 0
+        current_race[2] = 0
+        gdb.execute('seek-user-time ' + str(next_race_time))
+
+FFToRaceCommand()
+
+class RWToRaceCommand(gdb.Command):
+    """Rewind program execution to the previous race before this time.
+
+Usage: cilksan rw-to-race
+
+Seek to the previous determinacy race before the current point in the replay.
+Update the current race target."""
+
+    def __init__(self):
+        super(RWToRaceCommand, self).__init__('cilksan rw-to-race',
+                                              gdb.COMMAND_RUNNING,
+                                              gdb.COMPLETE_NONE, False)
+
+    def invoke(self, arg, from_tty):
+        if len(races) == 0:
+            print(no_races_error_msg)
+            return
+        # Get the current user time
+        when_user_time = gdb.execute('when-user-time', False, True)
+        parse = re.search("Current\s+user\s+time:\s+(-?\d+)", when_user_time)
+        current_user_time = int(parse.group(1))
+
+        # Binary search for the next race after the current user time
+        start = 0
+        end = len(races)
+        while end - start > 1:
+            mid = start + ((end - start) // 2)
+            prev_race_time = time_for_race(mid)
+            if prev_race_time < current_user_time:
+                start = mid
+            else:
+                end = mid
+        if time_for_race(start) >= current_user_time:
+            if start == 0:
+                print("No races before this point in the replay.")
+                return
+            start = start - 1
+
+        # Seek to the race
+        next_race_time = time_for_race(start)
+        current_race[0] = start
+        current_race[1] = 0
+        current_race[2] = 0
+        gdb.execute('seek-user-time ' + str(next_race_time))
+
+RWToRaceCommand()
+
 class ToggleRaceCommand(gdb.Command):
     """Seek program execution to the opposite racing instruction.