From 86702186f28770daf215737b89e7ba82e8fcc640 Mon Sep 17 00:00:00 2001
From: Eladash <elad3356p@gmail.com>
Date: Thu, 18 Aug 2022 16:10:24 +0300
Subject: [PATCH] PPU: Detect lwmutex reservation pattern and optimize it

---
 rpcs3/Emu/Cell/PPUThread.cpp | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/rpcs3/Emu/Cell/PPUThread.cpp b/rpcs3/Emu/Cell/PPUThread.cpp
index a8b3ed69a0..b15b06f8a5 100644
--- a/rpcs3/Emu/Cell/PPUThread.cpp
+++ b/rpcs3/Emu/Cell/PPUThread.cpp
@@ -2640,7 +2640,15 @@ static bool ppu_store_reservation(ppu_thread& ppu, u32 addr, u64 reg_value)
 		return false;
 	}())
 	{
-		res.notify_all(-128);
+		// Test a common pattern in lwmutex
+		constexpr u64 mutex_free = u64{static_cast<u32>(0 - 1)} << 32;
+		const bool may_be_lwmutex_related = sizeof(T) == 8 ?
+			(new_data == mutex_free && old_data == u64{ppu.id} << 32) : (old_data == mutex_free && new_data == u64{ppu.id} << 32);
+
+		if (!may_be_lwmutex_related)
+		{
+			res.notify_all(-128);
+		}
 
 		if (addr == ppu.last_faddr)
 		{