Extended the profiling API. When using the variable stack trace depth

buffer format, the buffer can now also contain other events than just
stack traces. ATM these are only references to the image events
(created/deleted). Therefore we no longer have to flush the profiling
buffer after such an event, since the debugger can exactly match the
samples. Since we couldn't flush when the profiling timer hit while the
thread was in the kernel, that wasn't working that well anyway.
"profile -f" fails to translate stack trace addresses only very rarely,
now.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@27775 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/debug/user_debugger.cpp

@@ -1192,11 +1192,25 @@ profiling_do_sample(bool& flushBuffer)
 
 	// Check, whether the buffer is full or an image event occurred since the
 	// last sample was taken.
+	int32 maxSamples = debugInfo.profile.max_samples;
 	int32 sampleCount = debugInfo.profile.sample_count;
 	int32 stackDepth = debugInfo.profile.stack_depth;
 	int32 imageEvent = thread->team->debug_info.image_event;
 	if (debugInfo.profile.sample_count > 0) {
-		if (debugInfo.profile.image_event < imageEvent
+		if (debugInfo.profile.last_image_event < imageEvent
+			&& debugInfo.profile.variable_stack_depth
+			&& sampleCount + 2 <= maxSamples) {
+			// an image event occurred, but we use variable stack depth and
+			// have enough room in the buffer to indicate an image event
+			addr_t* event = debugInfo.profile.samples + sampleCount;
+			event[0] = B_DEBUG_PROFILE_IMAGE_EVENT;
+			event[1] = imageEvent;
+			sampleCount += 2;
+			debugInfo.profile.sample_count = sampleCount;
+			debugInfo.profile.last_image_event = imageEvent;
+		}
+
+		if (debugInfo.profile.last_image_event < imageEvent
 			|| debugInfo.profile.flush_threshold - sampleCount < stackDepth) {
 			if (!IS_KERNEL_ADDRESS(arch_debug_get_interrupt_pc())) {
 				flushBuffer = true;
@@ -1206,7 +1220,7 @@ profiling_do_sample(bool& flushBuffer)
 			// We can't flush the buffer now, since we interrupted a kernel
 			// function. If the buffer is not full yet, we add the samples,
 			// otherwise we have to drop them.
-			if (debugInfo.profile.max_samples - sampleCount < stackDepth) {
+			if (maxSamples - sampleCount < stackDepth) {
 				debugInfo.profile.dropped_ticks++;
 				return true;
 			}
@@ -1214,6 +1228,7 @@ profiling_do_sample(bool& flushBuffer)
 	} else {
 		// first sample -- set the image event
 		debugInfo.profile.image_event = imageEvent;
+		debugInfo.profile.last_image_event = imageEvent;
 	}
 
 	// get the samples
@@ -2300,6 +2315,8 @@ debug_nub_thread(void *)
 							threadDebugInfo.profile.interval_left = interval;
 							threadDebugInfo.profile.installed_timer = NULL;
 							threadDebugInfo.profile.image_event = imageEvent;
+							threadDebugInfo.profile.last_image_event
+								= imageEvent;
 						} else
 							result = B_BAD_VALUE;
 					} else