From aa7b13f35344d077b43b3be8a368ce3e998d6fb9 Mon Sep 17 00:00:00 2001
From: Martino Fontana <tinozzo123@gmail.com>
Date: Thu, 19 Jun 2025 15:41:02 +0200
Subject: [PATCH] PPCDebugInterface: Small refactor to ApplyMemoryPatch
 Invalidate icache only if target address has a different value. Take separate
 arguements, instead of a struct, to allow easier usage elsewhere. Overload
 with u8, u16 and u32 values for the same reason.

---
 .../Core/Core/Debugger/PPCDebugInterface.cpp  | 37 ++++++++++---------
 Source/Core/Core/Debugger/PPCDebugInterface.h | 14 ++++++-
 2 files changed, 33 insertions(+), 18 deletions(-)

diff --git a/Source/Core/Core/Debugger/PPCDebugInterface.cpp b/Source/Core/Core/Debugger/PPCDebugInterface.cpp
index 2c840d0ae5..92a0a26ea8 100644
--- a/Source/Core/Core/Debugger/PPCDebugInterface.cpp
+++ b/Source/Core/Core/Debugger/PPCDebugInterface.cpp
@@ -29,55 +29,58 @@
 #include "Core/PowerPC/PowerPC.h"
 #include "Core/System.h"
 
-void ApplyMemoryPatch(const Core::CPUThreadGuard& guard, Common::Debug::MemoryPatch& patch,
+void ApplyMemoryPatch(const Core::CPUThreadGuard& guard, std::span<u8> value, const u32 address,
                       bool store_existing_value)
 {
   if (AchievementManager::GetInstance().IsHardcoreModeActive())
     return;
 
-  if (patch.value.empty())
+  if (value.empty())
     return;
 
-  const u32 address = patch.address;
-  const std::size_t size = patch.value.size();
+  const std::size_t size = value.size();
   if (!PowerPC::MMU::HostIsRAMAddress(guard, address))
     return;
 
   auto& power_pc = guard.GetSystem().GetPowerPC();
+
+  bool should_invalidate_cache = false;
   for (u32 offset = 0; offset < size; ++offset)
   {
-    if (store_existing_value)
+    u8 old_value = PowerPC::MMU::HostRead_U8(guard, address + offset);
+    if (old_value != value[offset])
     {
-      const u8 value = PowerPC::MMU::HostRead_U8(guard, address + offset);
-      PowerPC::MMU::HostWrite_U8(guard, patch.value[offset], address + offset);
-      patch.value[offset] = value;
-    }
-    else
-    {
-      PowerPC::MMU::HostWrite_U8(guard, patch.value[offset], address + offset);
+      PowerPC::MMU::HostWrite_U8(guard, value[offset], address + offset);
+      should_invalidate_cache = true;
+      if (store_existing_value)
+        value[offset] = old_value;
     }
 
     if (((address + offset) % 4) == 3)
-      power_pc.ScheduleInvalidateCacheThreadSafe(Common::AlignDown(address + offset, 4));
+    {
+      if (should_invalidate_cache)
+        power_pc.ScheduleInvalidateCacheThreadSafe(Common::AlignDown(address + offset, 4));
+      should_invalidate_cache = false;
+    }
   }
-  if (((address + size) % 4) != 0)
+  if (should_invalidate_cache)
   {
     power_pc.ScheduleInvalidateCacheThreadSafe(
-        Common::AlignDown(address + static_cast<u32>(size), 4));
+        Common::AlignDown(address + static_cast<u32>(size) - 1, 4));
   }
 }
 
 void PPCPatches::ApplyExistingPatch(const Core::CPUThreadGuard& guard, std::size_t index)
 {
   auto& patch = m_patches[index];
-  ApplyMemoryPatch(guard, patch, false);
+  ApplyMemoryPatch(guard, patch.value, patch.address, false);
 }
 
 void PPCPatches::Patch(const Core::CPUThreadGuard& guard, std::size_t index)
 {
   auto& patch = m_patches[index];
   if (patch.type == Common::Debug::MemoryPatch::ApplyType::Once)
-    ApplyMemoryPatch(guard, patch);
+    ApplyMemoryPatch(guard, patch.value, patch.address);
   else
     PatchEngine::AddMemoryPatch(index);
 }
diff --git a/Source/Core/Core/Debugger/PPCDebugInterface.h b/Source/Core/Core/Debugger/PPCDebugInterface.h
index 797f2d5254..c68864583d 100644
--- a/Source/Core/Core/Debugger/PPCDebugInterface.h
+++ b/Source/Core/Core/Debugger/PPCDebugInterface.h
@@ -3,12 +3,15 @@
 
 #pragma once
 
+#include <concepts>
 #include <cstddef>
 #include <memory>
+#include <span>
 #include <string>
 
 #include "Common/Debug/MemoryPatches.h"
 #include "Common/Debug/Watches.h"
+#include "Common/Swap.h"
 #include "Core/Debugger/DebugInterface.h"
 #include "Core/NetworkCaptureLogger.h"
 
@@ -19,9 +22,18 @@ class System;
 }  // namespace Core
 class PPCSymbolDB;
 
-void ApplyMemoryPatch(const Core::CPUThreadGuard&, Common::Debug::MemoryPatch& patch,
+void ApplyMemoryPatch(const Core::CPUThreadGuard& guard, std::span<u8> value, const u32 address,
                       bool store_existing_value = true);
 
+template <std::unsigned_integral T>
+void ApplyMemoryPatch(const Core::CPUThreadGuard& guard, T value, const u32 address)
+{
+  Common::BigEndianValue<T> big_endian{value};
+  auto data =
+      std::span<u8, sizeof(T)>{reinterpret_cast<u8*>(std::addressof(big_endian)), sizeof(T)};
+  ApplyMemoryPatch(guard, data, address);
+}
+
 class PPCPatches final : public Common::Debug::MemoryPatches
 {
 public: