GP-1222: Added comparison between times in a trace.

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/database/DBTraceUtils.java

@@ -19,7 +19,6 @@ import java.lang.reflect.Field;
 import java.net.MalformedURLException;
 import java.net.URL;
 import java.nio.ByteBuffer;
-import java.nio.charset.Charset;
 import java.util.Iterator;
 import java.util.Objects;
 import java.util.function.BiConsumer;

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/database/memory/DBTraceMemoryManager.java

@@ -327,6 +327,17 @@ public class DBTraceMemoryManager
 		return delegateRead(start.getAddressSpace(), m -> m.getBufferAt(snap, start, byteOrder));
 	}
 
+	@Override
+	public Long getSnapOfMostRecentChangeToBlock(long snap, Address address) {
+		return delegateRead(address.getAddressSpace(),
+			m -> m.getSnapOfMostRecentChangeToBlock(snap, address));
+	}
+
+	@Override
+	public int getBlockSize() {
+		return DBTraceMemorySpace.BLOCK_SIZE;
+	}
+
 	@Override
 	public void pack() {
 		delegateWriteAll(getActiveSpaces(), m -> m.pack());

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/database/memory/DBTraceMemorySpace.java

@@ -875,6 +875,26 @@ public class DBTraceMemorySpace implements Unfinished, TraceMemorySpace, DBTrace
 		return false;
 	}
 
+	@Override
+	public Long getSnapOfMostRecentChangeToBlock(long snap, Address address) {
+		assertInSpace(address);
+		try (LockHold hold = LockHold.lock(lock.readLock())) {
+			long offset = address.getOffset();
+			long roundOffset = offset & BLOCK_MASK;
+			OffsetSnap loc = new OffsetSnap(roundOffset, snap);
+			DBTraceMemoryBlockEntry ent = findMostRecentBlockEntry(loc, true);
+			if (ent == null) {
+				return null;
+			}
+			return ent.getSnap();
+		}
+	}
+
+	@Override
+	public int getBlockSize() {
+		return BLOCK_SIZE;
+	}
+
 	public long getFirstChange(Range<Long> span, AddressRange range) {
 		assertInSpace(range);
 		long lower = DBTraceUtils.lowerEndpoint(span);

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/memory/TraceMemoryOperations.java

@@ -472,6 +472,32 @@ public interface TraceMemoryOperations {
 					: ByteOrder.LITTLE_ENDIAN);
 	}
 
+	/**
+	 * Find the internal storage block that most-recently defines the value at the given snap and
+	 * address, and return the block's snap.
+	 * 
+	 * <p>
+	 * This method reveals portions of the internal storage so that clients can optimize difference
+	 * computations by eliminating corresponding ranges defined by the same block. If the underlying
+	 * implementation cannot answer this question, this returns the given snap.
+	 * 
+	 * @param snap the time
+	 * @param address the location
+	 * @return the most snap for the most recent containing block
+	 */
+	Long getSnapOfMostRecentChangeToBlock(long snap, Address address);
+
+	/**
+	 * Get the block size used by internal storage.
+	 * 
+	 * <p>
+	 * This method reveals portions of the internal storage so that clients can optimize searches.
+	 * If the underlying implementation cannot answer this question, this returns 0.
+	 * 
+	 * @return the block size
+	 */
+	int getBlockSize();
+
 	/**
 	 * Optimize storage space
 	 * 

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/time/schedule/Sequence.java

@@ -368,7 +368,7 @@ public class Sequence implements Comparable<Sequence> {
 	 * 
 	 * @param trace the trace to which the machine is bound
 	 * @param eventThread the thread for the first step, if it applies to the "last thread"
-	 * @param machine the machine to step
+	 * @param machine the machine to step, or null to validate the sequence
 	 * @param action the action to step each thread
 	 * @param monitor a monitor for cancellation and progress reports
 	 * @return the last trace thread stepped during execution
@@ -384,6 +384,22 @@ public class Sequence implements Comparable<Sequence> {
 		return thread;
 	}
 
+	/**
+	 * Validate this sequence for the given trace
+	 * 
+	 * @param trace the trace
+	 * @param eventThread the thread for the first step, if it applies to the "last thread"
+	 * @return the last trace thread that would be stepped by this sequence
+	 */
+	public TraceThread validate(Trace trace, TraceThread eventThread) {
+		try {
+			return execute(trace, eventThread, null, null, null);
+		}
+		catch (CancelledException e) {
+			throw new AssertionError(e);
+		}
+	}
+
 	/**
 	 * Get the key of the last thread stepped
 	 * 

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/time/schedule/Step.java

@@ -91,8 +91,8 @@ public interface Step extends Comparable<Step> {
 		TraceThread thread = isEventThread() ? eventThread : tm.getThread(getThreadKey());
 		if (thread == null) {
 			if (isEventThread()) {
-				throw new IllegalArgumentException(
-					"Thread key -1 can only be used if last/event thread is given");
+				throw new IllegalArgumentException("Thread must be given, e.g., 0:t1-3, " +
+					"since the last thread or snapshot event thread is not given.");
 			}
 			throw new IllegalArgumentException(
 				"Thread with key " + getThreadKey() + " does not exist in given trace");
@@ -160,6 +160,10 @@ public interface Step extends Comparable<Step> {
 			PcodeMachine<T> machine, Consumer<PcodeThread<T>> stepAction, TaskMonitor monitor)
 			throws CancelledException {
 		TraceThread thread = getThread(tm, eventThread);
+		if (machine == null) {
+			// Just performing validation (specifically thread parts)
+			return thread;
+		}
 		PcodeThread<T> emuThread = machine.getThread(thread.getPath(), true);
 		execute(emuThread, stepAction, monitor);
 		return thread;

Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/model/time/schedule/TraceSchedule.java

@@ -344,6 +344,22 @@ public class TraceSchedule implements Comparable<TraceSchedule> {
 			pSteps.execute(trace, lastThread, machine, PcodeThread::stepPcodeOp, monitor);
 	}
 
+	/**
+	 * Validate this schedule for the given trace
+	 * 
+	 * <p>
+	 * This performs a dry run of the sequence on the given trace. If the schedule starts on the
+	 * "last thread," it verifies the snapshot gives the event thread. It also checks that every
+	 * thread key in the sequence exists in the trace.
+	 * 
+	 * @param trace the trace against which to validate this schedule
+	 */
+	public void validate(Trace trace) {
+		TraceThread lastThread = getEventThread(trace);
+		lastThread = steps.validate(trace, lastThread);
+		lastThread = pSteps.validate(trace, lastThread);
+	}
+
 	/**
 	 * Realize the machine state for this schedule using the given trace and pre-positioned machine
 	 * 
@@ -385,13 +401,13 @@ public class TraceSchedule implements Comparable<TraceSchedule> {
 	 * This schedule is left unmodified. If it had any p-code steps, those steps are dropped in the
 	 * resulting schedule.
 	 * 
-	 * @param thread the thread to step
+	 * @param thread the thread to step, or null for the "last thread"
 	 * @param tickCount the number of ticks to take the thread forward
 	 * @return the resulting schedule
 	 */
 	public TraceSchedule steppedForward(TraceThread thread, long tickCount) {
 		Sequence steps = this.steps.clone();
-		steps.advance(new TickStep(thread.getKey(), tickCount));
+		steps.advance(new TickStep(thread == null ? -1 : thread.getKey(), tickCount));
 		return new TraceSchedule(snap, steps, new Sequence());
 	}
 
@@ -441,13 +457,13 @@ public class TraceSchedule implements Comparable<TraceSchedule> {
 	 * Returns the equivalent of executing the schedule followed by stepping the given thread
 	 * {@code pTickCount} more p-code operations
 	 * 
-	 * @param thread the thread to step
+	 * @param thread the thread to step, or null for the "last thread"
 	 * @param pTickCount the number of p-code ticks to take the thread forward
 	 * @return the resulting schedule
 	 */
 	public TraceSchedule steppedPcodeForward(TraceThread thread, int pTickCount) {
 		Sequence pTicks = this.pSteps.clone();
-		pTicks.advance(new TickStep(thread.getKey(), pTickCount));
+		pTicks.advance(new TickStep(thread == null ? -1 : thread.getKey(), pTickCount));
 		return new TraceSchedule(snap, steps.clone(), pTicks);
 	}