Fix shutdown performance regression

Author: hrydgard

Core/HLE/AtracCtx2.cpp

@@ -29,9 +29,6 @@
 // cmd1> C:\dev\ppsspp\pspautotests\tests\audio\atrac>copy /Y ..\..\..\__testoutput.txt stream.expected
 // Then run the test, see above.
 
-// TODO: Add an AT3 dumping facility (and/or replacement?). Although the old implementation could do it more easily...
-
-
 struct AT3BitrateMeta {
 	u16 sampleSize;
 	u8 dataByte;

Core/MIPS/JitCommon/JitBlockCache.cpp

@@ -120,10 +120,11 @@ void JitBlockCache::Shutdown() {
 // This clears the JIT cache. It's called from JitCache.cpp when the JIT cache
 // is full and when saving and loading states.
 void JitBlockCache::Clear() {
+	// Note: We intentionally clear the block_map_ first to avoid O(N^2) behavior in RemoveBlockMap
+	block_map_.clear();
 	for (int i = 0; i < num_blocks_; i++) {
 		DestroyBlock(i, DestroyType::CLEAR);
 	}
-	block_map_.clear();
 	proxyBlockMap_.clear();
 	links_to_.clear();
 	num_blocks_ = 0;
@@ -238,6 +239,7 @@ void JitBlockCache::RemoveBlockMap(int block_num) {
 		// TODO: This is O(n), so O(n^2) when called for every block.
 		for (auto it = block_map_.begin(); it != block_map_.end(); ++it) {
 			if (it->second == (u32)block_num) {
+				_dbg_assert_(false);
 				block_map_.erase(it);
 				break;
 			}