X-Git-Url: http://plrg.eecs.uci.edu/git/?p=c11tester.git;a=blobdiff_plain;f=datarace.cc;h=dd88c2fe98f095d678e55c3dbf1162d98298b9d7;hp=da9a3fc15c9716a5a0ec7320bf23bccfb5445ef1;hb=bb18310b8c8c97d8e396940bdfee740bd6d3e30a;hpb=bcb3a311780c22c8a344c1288f1dd883b7b1960a

diff --git a/datarace.cc b/datarace.cc
index da9a3fc1..dd88c2fe 100644
--- a/datarace.cc
+++ b/datarace.cc
@@ -1,95 +1,341 @@
 #include "datarace.h"
-#include "threads.h"
+#include "model.h"
+#include "threads-model.h"
 #include <stdio.h>
 #include <cstring>
+#include "mymemory.h"
+#include "clockvector.h"
+#include "config.h"
+#include "action.h"
+#include "execution.h"
+#include "stl-model.h"
+#include <execinfo.h>
+
+static struct ShadowTable *root;
+static void *memory_base;
+static void *memory_top;
+static RaceSet * raceset;
+
+static const ModelExecution * get_execution()
+{
+	return model->get_execution();
+}
 
-struct ShadowTable *root;
+/** This function initialized the data race detector. */
+void initRaceDetector()
+{
+	root = (struct ShadowTable *)snapshot_calloc(sizeof(struct ShadowTable), 1);
+	memory_base = snapshot_calloc(sizeof(struct ShadowBaseTable) * SHADOWBASETABLES, 1);
+	memory_top = ((char *)memory_base) + sizeof(struct ShadowBaseTable) * SHADOWBASETABLES;
+	raceset = new RaceSet();
+}
 
-void initRaceDetector() {
-	root=(struct ShadowTable *) calloc(sizeof(struct ShadowTable),1);
+void * table_calloc(size_t size)
+{
+	if ((((char *)memory_base) + size) > memory_top) {
+		return snapshot_calloc(size, 1);
+	} else {
+		void *tmp = memory_base;
+		memory_base = ((char *)memory_base) + size;
+		return tmp;
+	}
 }
 
-static uint64_t * lookupAddressEntry(void * address) {
-	struct ShadowTable *currtable=root;
-#ifdef BIT48
-	currtable=(struct ShadowTable *) currtable->array[(((uintptr_t)address)>>32)&0xffff];
-	if (currtable==NULL) {
-		currtable=(struct ShadowTable *) (root->array[(((uintptr_t)address)>>32)&MASK16BIT]=calloc(sizeof(struct ShadowTable),1));
+/** This function looks up the entry in the shadow table corresponding to a
+ * given address.*/
+static uint64_t * lookupAddressEntry(const void *address)
+{
+	struct ShadowTable *currtable = root;
+#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] = table_calloc(sizeof(struct ShadowTable)));
 	}
 #endif
 
-	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));
+	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] = table_calloc(sizeof(struct ShadowBaseTable)));
+	}
+	return &basetable->array[((uintptr_t)address) & MASK16BIT];
+}
+
+
+bool hasNonAtomicStore(const void *address) {
+	uint64_t * shadow = lookupAddressEntry(address);
+	uint64_t shadowval = *shadow;
+	if (ISSHORTRECORD(shadowval)) {
+		//Do we have a non atomic write with a non-zero clock
+		return ((WRITEVECTOR(shadowval) != 0) && !(ATOMICMASK & shadowval));
+	} else {
+		if (shadowval == 0)
+			return false;
+		struct RaceRecord *record = (struct RaceRecord *)shadowval;
+		return !record->isAtomic && record->writeClock != 0;
+	}
+}
+
+void setAtomicStoreFlag(const void *address) {
+	uint64_t * shadow = lookupAddressEntry(address);
+	uint64_t shadowval = *shadow;
+	if (ISSHORTRECORD(shadowval)) {
+		*shadow = shadowval | ATOMICMASK;
+	} else {
+		if (shadowval == 0)
+			return;
+		struct RaceRecord *record = (struct RaceRecord *)shadowval;
+		record->isAtomic = 1;
+	}
+}
+
+void getStoreThreadAndClock(const void *address, thread_id_t * thread, modelclock_t * clock) {
+	uint64_t * shadow = lookupAddressEntry(address);
+	uint64_t shadowval = *shadow;
+	if (ISSHORTRECORD(shadowval)) {
+		//Do we have a non atomic write with a non-zero clock
+		*thread = WRTHREADID(shadowval);
+		*clock = WRITEVECTOR(shadowval);
+	} else {
+		struct RaceRecord *record = (struct RaceRecord *)shadowval;
+		*thread = record->writeThread;
+		*clock = record->writeClock;
 	}
-	return &basetable->array[((uintptr_t)address)&MASK16BIT];
 }
 
-static void expandRecord(uint64_t * shadow) {
-	uint64_t shadowval=*shadow;
+/**
+ * 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;
 
 	modelclock_t readClock = READVECTOR(shadowval);
 	thread_id_t readThread = int_to_id(RDTHREADID(shadowval));
 	modelclock_t writeClock = WRITEVECTOR(shadowval);
 	thread_id_t writeThread = int_to_id(WRTHREADID(shadowval));
 
-	struct RaceRecord * record=(struct RaceRecord *)calloc(1,sizeof(struct RaceRecord));
-	record->writeThread=writeThread;
-	record->writeClock=writeClock;
+	struct RaceRecord *record = (struct RaceRecord *)snapshot_calloc(1, sizeof(struct RaceRecord));
+	record->writeThread = writeThread;
+	record->writeClock = writeClock;
+
+	if (readClock != 0) {
+		record->thread = (thread_id_t *)snapshot_malloc(sizeof(thread_id_t) * INITCAPACITY);
+		record->readClock = (modelclock_t *)snapshot_malloc(sizeof(modelclock_t) * INITCAPACITY);
+		record->numReads = 1;
+		ASSERT(readThread >= 0);
+		record->thread[0] = readThread;
+		record->readClock[0] = readClock;
+	}
+	if (shadowval & ATOMICMASK)
+		record->isAtomic = 1;
+	*shadow = (uint64_t) record;
+}
 
-	if (readClock!=0) {
-		record->capacity=INITCAPACITY;
-		record->thread=(thread_id_t *) malloc(sizeof(thread_id_t)*record->capacity);
-		record->readClock=(modelclock_t *) malloc(sizeof(modelclock_t)*record->capacity);
-		record->numReads=1;
-		record->thread[0]=readThread;
-		record->readClock[0]=readClock;
+#define FIRST_STACK_FRAME 2
+
+unsigned int race_hash(struct DataRace *race) {
+	unsigned int hash = 0;
+	for(int i=FIRST_STACK_FRAME;i < race->numframes;i++) {
+		hash ^= ((uintptr_t)race->backtrace[i]);
+		hash = (hash >> 3) | (hash << 29);
 	}
-	*shadow=(uint64_t) record;
+	return hash;
 }
 
-static void reportDataRace() {
-	printf("The reportDataRace method should report useful things about this datarace!\n");
+
+bool race_equals(struct DataRace *r1, struct DataRace *r2) {
+	if (r1->numframes != r2->numframes)
+		return false;
+	for(int i=FIRST_STACK_FRAME;i < r1->numframes;i++) {
+		if (r1->backtrace[i] != r2->backtrace[i])
+			return false;
+	}
+	return true;
 }
 
-void fullRaceCheckWrite(thread_id_t thread, uint64_t * shadow, ClockVector *currClock) {
-	struct RaceRecord * record=(struct RaceRecord *) (*shadow);
+/** This function is called when we detect a data race.*/
+static struct DataRace * reportDataRace(thread_id_t oldthread, modelclock_t oldclock, bool isoldwrite, ModelAction *newaction, bool isnewwrite, const void *address)
+{
+	struct DataRace *race = (struct DataRace *)model_malloc(sizeof(struct DataRace));
+	race->oldthread = oldthread;
+	race->oldclock = oldclock;
+	race->isoldwrite = isoldwrite;
+	race->newaction = newaction;
+	race->isnewwrite = isnewwrite;
+	race->address = address;
+	return race;
+}
+
+/**
+ * @brief Assert a data race
+ *
+ * Asserts a data race which is currently realized, causing the execution to
+ * end and stashing a message in the model-checker's bug list
+ *
+ * @param race The race to report
+ */
+void assert_race(struct DataRace *race)
+{
+	model_print("Race detected at location: \n");
+	backtrace_symbols_fd(race->backtrace, race->numframes, model_out);
+	model_print("\nData race detected @ address %p:\n"
+							"    Access 1: %5s in thread %2d @ clock %3u\n"
+							"    Access 2: %5s in thread %2d @ clock %3u\n\n",
+							race->address,
+							race->isoldwrite ? "write" : "read",
+							id_to_int(race->oldthread),
+							race->oldclock,
+							race->isnewwrite ? "write" : "read",
+							id_to_int(race->newaction->get_tid()),
+							race->newaction->get_seq_number()
+							);
+}
+
+/** This function does race detection for a write on an expanded record. */
+struct DataRace * fullRaceCheckWrite(thread_id_t thread, void *location, uint64_t *shadow, ClockVector *currClock)
+{
+	struct RaceRecord *record = (struct RaceRecord *)(*shadow);
+	struct DataRace * race = NULL;
 
 	/* Check for datarace against last read. */
 
-	for(int i=0;i<record->numReads;i++) {
+	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();
+			race = reportDataRace(readThread, readClock, false, get_execution()->get_parent_action(thread), true, location);
+			goto Exit;
 		}
 	}
 
 	/* Check for datarace against last write. */
 
-	modelclock_t writeClock = record->writeClock;
-	thread_id_t writeThread = record->writeThread;
+	{
+		modelclock_t writeClock = record->writeClock;
+		thread_id_t writeThread = record->writeThread;
 
-	if (writeThread != thread && writeClock != 0 && currClock->getClock(writeThread) <= writeClock) {
-		/* We have a datarace */
-		reportDataRace();
+		if (clock_may_race(currClock, thread, writeClock, writeThread)) {
+			/* We have a datarace */
+			race = reportDataRace(writeThread, writeClock, true, get_execution()->get_parent_action(thread), true, location);
+			goto Exit;
+		}
 	}
-
-	record->numReads=0;
-	record->writeThread=thread;
+Exit:
+	record->numReads = 0;
+	record->writeThread = thread;
+	record->isAtomic = 0;
 	modelclock_t ourClock = currClock->getClock(thread);
-	record->writeClock=ourClock;
+	record->writeClock = ourClock;
+	return race;
 }
 
-void raceCheckWrite(thread_id_t thread, void *location, ClockVector *currClock) {
-	uint64_t * shadow=lookupAddressEntry(location);
-	uint64_t shadowval=*shadow;
+/** This function does race detection on a write. */
+void raceCheckWrite(thread_id_t thread, void *location)
+{
+	uint64_t *shadow = lookupAddressEntry(location);
+	uint64_t shadowval = *shadow;
+	ClockVector *currClock = get_execution()->get_cv(thread);
+	if (currClock == NULL)
+		return;
 
+	struct DataRace * race = NULL;
 	/* Do full record */
-	if (shadowval!=0&&!ISSHORTRECORD(shadowval)) {
-		fullRaceCheckWrite(thread, shadow, currClock);
+	if (shadowval != 0 && !ISSHORTRECORD(shadowval)) {
+		race = fullRaceCheckWrite(thread, location, shadow, currClock);
+		goto Exit;
+	}
+
+	{
+		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);
+			race = fullRaceCheckWrite(thread, location, shadow, currClock);
+			goto Exit;
+		}
+
+
+
+		{
+			/* Check for datarace against last read. */
+
+			modelclock_t readClock = READVECTOR(shadowval);
+			thread_id_t readThread = int_to_id(RDTHREADID(shadowval));
+
+			if (clock_may_race(currClock, thread, readClock, readThread)) {
+				/* We have a datarace */
+				race = reportDataRace(readThread, readClock, false, get_execution()->get_parent_action(thread), true, location);
+				goto ShadowExit;
+			}
+		}
+
+		{
+			/* Check for datarace against last write. */
+
+			modelclock_t writeClock = WRITEVECTOR(shadowval);
+			thread_id_t writeThread = int_to_id(WRTHREADID(shadowval));
+
+			if (clock_may_race(currClock, thread, writeClock, writeThread)) {
+				/* We have a datarace */
+				race = reportDataRace(writeThread, writeClock, true, get_execution()->get_parent_action(thread), true, location);
+				goto ShadowExit;
+			}
+		}
+
+ShadowExit:
+		*shadow = ENCODEOP(0, 0, threadid, ourClock);
+	}
+
+Exit:
+	if (race) {
+		race->numframes=backtrace(race->backtrace, sizeof(race->backtrace)/sizeof(void*));
+		if (raceset->add(race))
+			assert_race(race);
+		else model_free(race);
+	}
+}
+
+/** This function does race detection for a write on an expanded record. */
+void fullRecordWrite(thread_id_t thread, void *location, uint64_t *shadow, ClockVector *currClock) {
+	struct RaceRecord *record = (struct RaceRecord *)(*shadow);
+	record->numReads = 0;
+	record->writeThread = thread;
+	modelclock_t ourClock = currClock->getClock(thread);
+	record->writeClock = ourClock;
+	record->isAtomic = 1;
+}
+
+/** This function just updates metadata on atomic write. */
+void recordWrite(thread_id_t thread, void *location) {
+	uint64_t *shadow = lookupAddressEntry(location);
+	uint64_t shadowval = *shadow;
+	ClockVector *currClock = get_execution()->get_cv(thread);
+	/* Do full record */
+	if (shadowval != 0 && !ISSHORTRECORD(shadowval)) {
+		fullRecordWrite(thread, location, shadow, currClock);
 		return;
 	}
 
@@ -99,122 +345,141 @@ void raceCheckWrite(thread_id_t thread, void *location, ClockVector *currClock)
 	/* Thread ID is too large or clock is too large. */
 	if (threadid > MAXTHREADID || ourClock > MAXWRITEVECTOR) {
 		expandRecord(shadow);
-		fullRaceCheckWrite(thread, shadow, currClock);
+		fullRecordWrite(thread, location, 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) {
-		/* We have a datarace */
-		reportDataRace();
-	}
-
-	/* Check for datarace against last write. */
-
-	modelclock_t writeClock = WRITEVECTOR(shadowval);
-	thread_id_t writeThread = int_to_id(WRTHREADID(shadowval));
-
-	if (writeThread != thread && writeClock != 0 && currClock->getClock(writeThread) <= writeClock) {
-		/* We have a datarace */
-		reportDataRace();
-	}
-	*shadow = ENCODEOP(0, 0, threadid, ourClock);
+	*shadow = ENCODEOP(0, 0, threadid, ourClock) | ATOMICMASK;
 }
 
-void fullRaceCheckRead(thread_id_t thread, uint64_t * shadow, ClockVector *currClock) {
-	struct RaceRecord * record=(struct RaceRecord *) (*shadow);
 
+
+/** This function does race detection on a read for an expanded record. */
+struct DataRace * fullRaceCheckRead(thread_id_t thread, const void *location, uint64_t *shadow, ClockVector *currClock)
+{
+	struct RaceRecord *record = (struct RaceRecord *) (*shadow);
+	struct DataRace * race = NULL;
 	/* 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();
+		race = reportDataRace(writeThread, writeClock, true, get_execution()->get_parent_action(thread), false, location);
 	}
 
 	/* Shorten vector when possible */
 
-	int copytoindex=0;
+	int copytoindex = 0;
 
-	for(int i=0;i<record->numReads;i++) {
+	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 cannot
+		                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];
-				record->thread[copytoindex]=record->thread[i];
+			if (copytoindex != i) {
+				ASSERT(record->thread[i] >= 0);
+				record->readClock[copytoindex] = record->readClock[i];
+				record->thread[copytoindex] = record->thread[i];
 			}
 			copytoindex++;
 		}
 	}
 
-	if (copytoindex>=record->capacity) {
-		int newCapacity=record->capacity*2;
-		thread_id_t *newthread=(thread_id_t *) malloc(sizeof(thread_id_t)*newCapacity);
-		modelclock_t * newreadClock=(modelclock_t *) malloc(sizeof(modelclock_t)*newCapacity);
-		std::memcpy(newthread, record->thread, record->capacity*sizeof(thread_id_t));
-		std::memcpy(newreadClock, record->readClock, record->capacity*sizeof(modelclock_t));
-		free(record->readClock);
-		free(record->thread);
-		record->readClock=newreadClock;
-		record->thread=newthread;
-		record->capacity=newCapacity;
+	if (__builtin_popcount(copytoindex) <= 1) {
+		if (copytoindex == 0) {
+			int newCapacity = INITCAPACITY;
+			record->thread = (thread_id_t *)snapshot_malloc(sizeof(thread_id_t) * newCapacity);
+			record->readClock = (modelclock_t *)snapshot_malloc(sizeof(modelclock_t) * newCapacity);
+		} else if (copytoindex>=INITCAPACITY) {
+			int newCapacity = copytoindex * 2;
+			thread_id_t *newthread = (thread_id_t *)snapshot_malloc(sizeof(thread_id_t) * newCapacity);
+			modelclock_t *newreadClock = (modelclock_t *)snapshot_malloc(sizeof(modelclock_t) * newCapacity);
+			std::memcpy(newthread, record->thread, copytoindex * sizeof(thread_id_t));
+			std::memcpy(newreadClock, record->readClock, copytoindex * sizeof(modelclock_t));
+			snapshot_free(record->readClock);
+			snapshot_free(record->thread);
+			record->readClock = newreadClock;
+			record->thread = newthread;
+		}
 	}
 
 	modelclock_t ourClock = currClock->getClock(thread);
 
-	record->thread[copytoindex]=thread;
-	record->readClock[copytoindex]=ourClock;
-	record->numReads=copytoindex+1;
+	ASSERT(thread >= 0);
+	record->thread[copytoindex] = thread;
+	record->readClock[copytoindex] = ourClock;
+	record->numReads = copytoindex + 1;
+	return race;
 }
 
-void raceCheckRead(thread_id_t thread, void *location, ClockVector *currClock) {
-	uint64_t * shadow=lookupAddressEntry(location);
-	uint64_t shadowval=*shadow;
+/** This function does race detection on a read. */
+void raceCheckRead(thread_id_t thread, const void *location)
+{
+	uint64_t *shadow = lookupAddressEntry(location);
+	uint64_t shadowval = *shadow;
+	ClockVector *currClock = get_execution()->get_cv(thread);
+	if (currClock == NULL)
+		return;
+
+	struct DataRace * race = NULL;
 
 	/* Do full record */
-	if (shadowval!=0&&!ISSHORTRECORD(shadowval)) {
-		fullRaceCheckRead(thread, shadow, currClock);
-		return;
+	if (shadowval != 0 && !ISSHORTRECORD(shadowval)) {
+		race = fullRaceCheckRead(thread, location, shadow, currClock);
+		goto Exit;
 	}
 
-	int threadid = id_to_int(thread);
-	modelclock_t ourClock = currClock->getClock(thread);
+	{
+		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);
-		fullRaceCheckRead(thread, shadow, currClock);
-		return;
-	}
+		/* Thread ID is too large or clock is too large. */
+		if (threadid > MAXTHREADID || ourClock > MAXWRITEVECTOR) {
+			expandRecord(shadow);
+			race = fullRaceCheckRead(thread, location, shadow, currClock);
+			goto Exit;
+		}
 
-	/* Check for datarace against last write. */
+		/* Check for datarace against last write. */
 
-	modelclock_t writeClock = WRITEVECTOR(shadowval);
-	thread_id_t writeThread = int_to_id(WRTHREADID(shadowval));
+		modelclock_t writeClock = WRITEVECTOR(shadowval);
+		thread_id_t writeThread = int_to_id(WRTHREADID(shadowval));
 
-	if (writeThread != thread && writeClock != 0 && currClock->getClock(writeThread) <= writeClock) {
-		/* We have a datarace */
-		reportDataRace();
-	}
+		if (clock_may_race(currClock, thread, writeClock, writeThread)) {
+			/* We have a datarace */
+			race = reportDataRace(writeThread, writeClock, true, get_execution()->get_parent_action(thread), false, location);
+			goto ShadowExit;
+		}
 
-	modelclock_t readClock = READVECTOR(shadowval);
-	thread_id_t readThread = int_to_id(RDTHREADID(shadowval));
+ShadowExit:
+		{
+			modelclock_t readClock = READVECTOR(shadowval);
+			thread_id_t readThread = int_to_id(RDTHREADID(shadowval));
 
-	if (readThread != thread && readClock != 0 && currClock->getClock(readThread) <= readClock) {
-		/* We don't subsume this read... Have to expand record. */
-		expandRecord(shadow);
-		fullRaceCheckRead(thread, shadow, currClock);
-		return;
-	}
+			if (clock_may_race(currClock, thread, readClock, readThread)) {
+				/* We don't subsume this read... Have to expand record. */
+				expandRecord(shadow);
+				fullRaceCheckRead(thread, location, shadow, currClock);
+				goto Exit;
+			}
+		}
 
-	*shadow = ENCODEOP(writeThread, writeClock, threadid, ourClock);
+		*shadow = ENCODEOP(threadid, ourClock, id_to_int(writeThread), writeClock) | (shadowval & ATOMICMASK);
+	}
+Exit:
+	if (race) {
+		race->numframes=backtrace(race->backtrace, sizeof(race->backtrace)/sizeof(void*));
+		if (raceset->add(race))
+			assert_race(race);
+		else model_free(race);
+	}
 }