renderer: avoid allocating for dirty range probes

src/graphics/host_gpu/rangeSet.h

@@ -59,6 +59,15 @@ public:
 		return result;
 	}
 
+	[[nodiscard]] bool Intersects(uint64_t address, uint64_t size) const {
+		const auto end = End(address, size);
+		auto       it  = m_ranges.lower_bound(address);
+		if (it != m_ranges.begin() && std::prev(it)->second > address) {
+			return true;
+		}
+		return it != m_ranges.end() && it->first < end;
+	}
+
 	[[nodiscard]] bool Contains(uint64_t address, uint64_t size) const {
 		const auto end = End(address, size);
 		auto       it  = m_ranges.upper_bound(address);

src/graphics/host_gpu/renderer/cache/bufferCache.cpp

@@ -167,7 +167,7 @@ void BufferCache::QueueGarbageDownload(std::span<const DownloadCopy> copies, Buf
 		// query therefore cannot orphan a dirty sibling on an edge page.
 		m_memory_tracker.UnmarkRegionAsGpuModified(address, size);
 		if (m_memory_tracker.IsRegionGpuModified(address, size) ||
-		    !m_gpu_modified_ranges.Intersections(address, size).empty()) {
+		    m_gpu_modified_ranges.Intersects(address, size)) {
 			EXIT("BufferCache: asynchronous garbage collection retained GPU ownership\n");
 		}
 		m_memory_tracker.UntrackMemory(address, size);
@@ -314,8 +314,7 @@ void BufferCache::UnmapMemory(uint64_t vaddr, uint64_t size) {
 		    !m_memory_tracker.IsRegionGpuModified(begin, buffer.Size())) {
 			continue;
 		}
-		const auto dirty = m_gpu_modified_ranges.Intersections(begin, buffer.Size());
+		if (!m_gpu_modified_ranges.Intersects(begin, buffer.Size())) {
-		if (dirty.empty()) {
 			EXIT("BufferCache: GPU-modified buffer has no dirty ranges\n");
 		}
 		modified_buffers.emplace_back(begin, buffer.Size());
@@ -350,7 +349,7 @@ void BufferCache::UnmapMemory(uint64_t vaddr, uint64_t size) {
 	for (const auto& [begin, bytes]: retired_buffers) {
 		m_memory_tracker.MarkRegionAsCpuModified(begin, bytes);
 	}
-	if (!m_gpu_modified_ranges.Intersections(vaddr, size).empty()) {
+	if (m_gpu_modified_ranges.Intersects(vaddr, size)) {
 		EXIT("BufferCache: unmap retained dirty byte ranges\n");
 	}
 	m_memory_tracker.UntrackMemory(vaddr, size);
@@ -557,8 +556,7 @@ std::pair<Buffer*, uint64_t> BufferCache::ObtainBufferForImage(uint64_t vaddr, u
 	{
 		const bool cpu_modified            = m_memory_tracker.IsRegionCpuModified(vaddr, size);
 		const bool gpu_modified            = m_memory_tracker.IsRegionGpuModified(vaddr, size);
-		const auto dirty                   = m_gpu_modified_ranges.Intersections(vaddr, size);
+		const bool has_dirty_buffer_source = m_gpu_modified_ranges.Intersects(vaddr, size);
-		const bool has_dirty_buffer_source = !dirty.empty();
 		m_memory_tracker.ValidateGpuDirtyOwnership(m_gpu_modified_ranges, vaddr, size,
 		                                           "image source");
 
@@ -592,8 +590,7 @@ std::pair<Buffer*, uint64_t> BufferCache::ObtainBufferForImage(uint64_t vaddr, u
 	}
 	m_staging_buffer.Commit();
 
-	const auto dirty                   = m_gpu_modified_ranges.Intersections(vaddr, size);
+	const bool has_dirty_buffer_source = m_gpu_modified_ranges.Intersects(vaddr, size);
-	const bool has_dirty_buffer_source = !dirty.empty();
 	auto*      owner                   = find_owner();
 	if (has_dirty_buffer_source && owner == nullptr) {
 		EXIT("BufferCache: GPU-dirty image source lost its native owner\n");
@@ -756,7 +753,7 @@ bool BufferCache::IsRegionGpuModified(uint64_t vaddr, uint64_t size) {
 }
 
 bool BufferCache::HasGpuDirtyBytes(uint64_t vaddr, uint64_t size) {
-	return !m_gpu_modified_ranges.Intersections(vaddr, size).empty();
+	return m_gpu_modified_ranges.Intersects(vaddr, size);
 }
 
 bool BufferCache::IsRegionCpuModified(uint64_t vaddr, uint64_t size) {

tests/MemoryTrackerTests.cpp

@@ -191,6 +191,10 @@ void TestRangeSet() {
   ranges.Add(0x1200, 0x40);
   Check(ranges.Contains(0x1010, 0xe0) && !ranges.Contains(0x1010, 0x200),
         "range set containment did not require full coverage");
+  Check(ranges.Intersects(0x0fff, 2) && ranges.Intersects(0x11ff, 2) &&
+            !ranges.Intersects(0x1100, 0x100) &&
+            !ranges.Intersects(0x1240, 1),
+        "range set intersection did not preserve half-open boundaries");
   auto intersections = ranges.Intersections(0x1070, 0x1b0);
   Check(intersections.size() == 2 && intersections[0].address == 0x1070 &&
             intersections[0].size == 0x90 &&