X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=datarace.cc;h=f0d3dc619489d780ea7e9be237b2007d428a4b33;hb=84e24d516d4e9dbd30f1fff7e9a185d1540d20eb;hp=12a2e6bb1d60aa84a94d0e970617e703c324ecc3;hpb=d2f35798cdae344760a0cc7f22dd5adc9cbc7081;p=model-checker.git

diff --git a/datarace.cc b/datarace.cc
index 12a2e6b..f0d3dc6 100644
--- a/datarace.cc
+++ b/datarace.cc
@@ -5,14 +5,17 @@
 
 struct ShadowTable *root;
 
+/** This function initialized the data race detector. */
 void initRaceDetector() {
 	root=(struct ShadowTable *) calloc(sizeof(struct ShadowTable),1);
 }
 
+/** This function looks up the entry in the shadow table corresponding to a
+ * given address.*/
 static uint64_t * lookupAddressEntry(void * address) {
 	struct ShadowTable *currtable=root;
-#ifdef BIT48
-	currtable=(struct ShadowTable *) currtable->array[(((uintptr_t)address)>>32)&0xffff];
+#if BIT48
+	currtable=(struct ShadowTable *) currtable->array[(((uintptr_t)address)>>32)&MASK16BIT];
 	if (currtable==NULL) {
 		currtable=(struct ShadowTable *) (root->array[(((uintptr_t)address)>>32)&MASK16BIT]=calloc(sizeof(struct ShadowTable),1));
 	}
@@ -21,10 +24,29 @@ static uint64_t * lookupAddressEntry(void * address) {
 	struct ShadowBaseTable * basetable=(struct ShadowBaseTable *) currtable->array[(((uintptr_t)address)>>16)&MASK16BIT];
 	if (basetable==NULL) {
 		basetable=(struct ShadowBaseTable *) (currtable->array[(((uintptr_t)address)>>16)&MASK16BIT]=calloc(sizeof(struct ShadowBaseTable),1));
-	}	
+	}
 	return &basetable->array[((uintptr_t)address)&MASK16BIT];
 }
 
+/**
+ * Compares a current clock-vector/thread-ID pair with a clock/thread-ID pair
+ * to check the potential for a data race.
+ * @param clock1 The current clock vector
+ * @param tid1 The current thread; paired with clock1
+ * @param clock2 The clock value for the potentially-racing action
+ * @param tid2 The thread ID for the potentially-racing action
+ * @return true if the current clock allows a race with the event at clock2/tid2
+ */
+static bool clock_may_race(ClockVector *clock1, thread_id_t tid1,
+                           modelclock_t clock2, thread_id_t tid2)
+{
+	return tid1 != tid2 && clock2 != 0 && clock1->getClock(tid2) <= clock2;
+}
+
+/**
+ * Expands a record from the compact form to the full form.  This is
+ * necessary for multiple readers or for very large thread ids or time
+ * stamps. */
 static void expandRecord(uint64_t * shadow) {
 	uint64_t shadowval=*shadow;
 
@@ -48,10 +70,12 @@ static void expandRecord(uint64_t * shadow) {
 	*shadow=(uint64_t) record;
 }
 
+/** This function is called when we detect a data race.*/
 static void reportDataRace() {
 	printf("The reportDataRace method should report useful things about this datarace!\n");
 }
 
+/** This function does race detection for a write on an expanded record. */
 void fullRaceCheckWrite(thread_id_t thread, uint64_t * shadow, ClockVector *currClock) {
 	struct RaceRecord * record=(struct RaceRecord *) (*shadow);
 
@@ -60,29 +84,33 @@ void fullRaceCheckWrite(thread_id_t thread, uint64_t * shadow, ClockVector *curr
 	for(int i=0;i<record->numReads;i++) {
 		modelclock_t readClock = record->readClock[i];
 		thread_id_t readThread = record->thread[i];
-		
-		if (readThread != thread && readClock != 0 && currClock->getClock(readThread) <= readClock) {
+
+		/* Note that readClock can't actuall be zero here, so it could be
+			 optimized. */
+
+		if (clock_may_race(currClock, thread, readClock, readThread)) {
 			/* We have a datarace */
 			reportDataRace();
 		}
 	}
-	
+
 	/* Check for datarace against last write. */
-	
+
 	modelclock_t writeClock = record->writeClock;
 	thread_id_t writeThread = record->writeThread;
-	
-	if (writeThread != thread && writeClock != 0 && currClock->getClock(writeThread) <= writeClock) {
+
+	if (clock_may_race(currClock, thread, writeClock, writeThread)) {
 		/* We have a datarace */
 		reportDataRace();
 	}
-	
+
 	record->numReads=0;
 	record->writeThread=thread;
 	modelclock_t ourClock = currClock->getClock(thread);
 	record->writeClock=ourClock;
 }
 
+/** This function does race detection on a write. */
 void raceCheckWrite(thread_id_t thread, void *location, ClockVector *currClock) {
 	uint64_t * shadow=lookupAddressEntry(location);
 	uint64_t shadowval=*shadow;
@@ -95,20 +123,20 @@ void raceCheckWrite(thread_id_t thread, void *location, ClockVector *currClock)
 
 	int threadid = id_to_int(thread);
 	modelclock_t ourClock = currClock->getClock(thread);
-	
+
 	/* Thread ID is too large or clock is too large. */
 	if (threadid > MAXTHREADID || ourClock > MAXWRITEVECTOR) {
 		expandRecord(shadow);
 		fullRaceCheckWrite(thread, shadow, currClock);
 		return;
 	}
-	
+
 	/* Check for datarace against last read. */
 
 	modelclock_t readClock = READVECTOR(shadowval);
 	thread_id_t readThread = int_to_id(RDTHREADID(shadowval));
 
-	if (readThread != thread && readClock != 0 && currClock->getClock(readThread) <= readClock) {
+	if (clock_may_race(currClock, thread, readClock, readThread)) {
 		/* We have a datarace */
 		reportDataRace();
 	}
@@ -117,23 +145,24 @@ void raceCheckWrite(thread_id_t thread, void *location, ClockVector *currClock)
 
 	modelclock_t writeClock = WRITEVECTOR(shadowval);
 	thread_id_t writeThread = int_to_id(WRTHREADID(shadowval));
-	
-	if (writeThread != thread && writeClock != 0 && currClock->getClock(writeThread) <= writeClock) {
+
+	if (clock_may_race(currClock, thread, writeClock, writeThread)) {
 		/* We have a datarace */
 		reportDataRace();
 	}
 	*shadow = ENCODEOP(0, 0, threadid, ourClock);
 }
 
+/** This function does race detection on a read for an expanded record. */
 void fullRaceCheckRead(thread_id_t thread, uint64_t * shadow, ClockVector *currClock) {
 	struct RaceRecord * record=(struct RaceRecord *) (*shadow);
 
 	/* Check for datarace against last write. */
-	
+
 	modelclock_t writeClock = record->writeClock;
 	thread_id_t writeThread = record->writeThread;
-	
-	if (writeThread != thread && writeClock != 0 && currClock->getClock(writeThread) <= writeClock) {
+
+	if (clock_may_race(currClock, thread, writeClock, writeThread)) {
 		/* We have a datarace */
 		reportDataRace();
 	}
@@ -145,8 +174,14 @@ void fullRaceCheckRead(thread_id_t thread, uint64_t * shadow, ClockVector *currC
 	for(int i=0;i<record->numReads;i++) {
 		modelclock_t readClock = record->readClock[i];
 		thread_id_t readThread = record->thread[i];
-		
-		if (readThread != thread && currClock->getClock(readThread) <= readClock) {
+
+		/*  Note that is not really a datarace check as reads cannott
+				actually race.  It is just determining that this read subsumes
+				another in the sense that either this read races or neither
+				read races. Note that readClock can't actually be zero, so it
+				could be optimized.  */
+
+		if (clock_may_race(currClock, thread, readClock, readThread)) {
 			/* Still need this read in vector */
 			if (copytoindex!=i) {
 				record->readClock[copytoindex]=record->readClock[i];
@@ -155,7 +190,7 @@ void fullRaceCheckRead(thread_id_t thread, uint64_t * shadow, ClockVector *currC
 			copytoindex++;
 		}
 	}
-	
+
 	if (copytoindex>=record->capacity) {
 		int newCapacity=record->capacity*2;
 		thread_id_t *newthread=(thread_id_t *) malloc(sizeof(thread_id_t)*newCapacity);
@@ -170,12 +205,13 @@ void fullRaceCheckRead(thread_id_t thread, uint64_t * shadow, ClockVector *currC
 	}
 
 	modelclock_t ourClock = currClock->getClock(thread);
-	
+
 	record->thread[copytoindex]=thread;
 	record->readClock[copytoindex]=ourClock;
 	record->numReads=copytoindex+1;
 }
 
+/** This function does race detection on a read. */
 void raceCheckRead(thread_id_t thread, void *location, ClockVector *currClock) {
 	uint64_t * shadow=lookupAddressEntry(location);
 	uint64_t shadowval=*shadow;
@@ -188,7 +224,7 @@ void raceCheckRead(thread_id_t thread, void *location, ClockVector *currClock) {
 
 	int threadid = id_to_int(thread);
 	modelclock_t ourClock = currClock->getClock(thread);
-	
+
 	/* Thread ID is too large or clock is too large. */
 	if (threadid > MAXTHREADID || ourClock > MAXWRITEVECTOR) {
 		expandRecord(shadow);
@@ -200,21 +236,21 @@ void raceCheckRead(thread_id_t thread, void *location, ClockVector *currClock) {
 
 	modelclock_t writeClock = WRITEVECTOR(shadowval);
 	thread_id_t writeThread = int_to_id(WRTHREADID(shadowval));
-	
-	if (writeThread != thread && writeClock != 0 && currClock->getClock(writeThread) <= writeClock) {
+
+	if (clock_may_race(currClock, thread, writeClock, writeThread)) {
 		/* We have a datarace */
 		reportDataRace();
 	}
-	
+
 	modelclock_t readClock = READVECTOR(shadowval);
 	thread_id_t readThread = int_to_id(RDTHREADID(shadowval));
 
-	if (readThread != thread && readClock != 0 && currClock->getClock(readThread) <= readClock) {
+	if (clock_may_race(currClock, thread, readClock, readThread)) {
 		/* We don't subsume this read... Have to expand record. */
 		expandRecord(shadow);
 		fullRaceCheckRead(thread, shadow, currClock);
 		return;
 	}
-		
+
 	*shadow = ENCODEOP(writeThread, writeClock, threadid, ourClock);
 }