Kernel: Remove Thread::wait_objects_index and use wait_objects to hold all the objects that a thread is waiting on.

src/core/hle/kernel/kernel.cpp

@@ -55,10 +55,16 @@ SharedPtr<Thread> WaitObject::GetHighestPriorityReadyThread() {
         if (ShouldWait(thread.get()))
             continue;
 
-        bool ready_to_run = std::none_of(thread->wait_objects.begin(), thread->wait_objects.end(),
+        // A thread is ready to run if it's either in THREADSTATUS_WAIT_SYNCH_ANY or
+        // in THREADSTATUS_WAIT_SYNCH_ALL and the rest of the objects it is waiting on are ready.
+        bool ready_to_run = true;
+        if (thread->status == THREADSTATUS_WAIT_SYNCH_ALL) {
+            ready_to_run = std::none_of(thread->wait_objects.begin(), thread->wait_objects.end(),
                                         [&thread](const SharedPtr<WaitObject>& object) {
                                             return object->ShouldWait(thread.get());
                                         });
+        }
+
         if (ready_to_run) {
             candidate = thread.get();
             candidate_priority = thread->current_priority;

src/core/hle/kernel/thread.cpp

@@ -579,6 +579,11 @@ void Thread::SetWaitSynchronizationOutput(s32 output) {
     context.cpu_registers[1] = output;
 }
 
+s32 Thread::GetWaitObjectIndex(WaitObject* object) const {
+    auto match = std::find(wait_objects.rbegin(), wait_objects.rend(), object);
+    return std::distance(match, wait_objects.rend()) - 1;
+}
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
 void ThreadingInit() {

src/core/hle/kernel/thread.h

@@ -135,13 +135,14 @@ public:
 
     /**
      * Retrieves the index that this particular object occupies in the list of objects
-     * that the thread passed to WaitSynchronizationN.
+     * that the thread passed to WaitSynchronizationN, starting the search from the last element.
      * It is used to set the output value of WaitSynchronizationN when the thread is awakened.
+     * When a thread wakes up due to an object signal, the kernel will use the index of the last
+     * matching object in the wait objects list in case of having multiple instances of the same
+     * object in the list.
      * @param object Object to query the index of.
      */
-    s32 GetWaitObjectIndex(const WaitObject* object) const {
-        return wait_objects_index.at(object->GetObjectId());
-    }
+    s32 GetWaitObjectIndex(WaitObject* object) const;
 
     /**
      * Stops a thread, invalidating it from further use
@@ -190,13 +191,10 @@ public:
 
     SharedPtr<Process> owner_process; ///< Process that owns this thread
 
-    /// Objects that the thread is waiting on.
-    /// This is only populated when the thread should wait for all the objects to become ready.
+    /// Objects that the thread is waiting on, in the same order as they were
+    // passed to WaitSynchronization1/N.
     std::vector<SharedPtr<WaitObject>> wait_objects;
 
-    /// Mapping of Object ids to their position in the last waitlist that this object waited on.
-    boost::container::flat_map<int, s32> wait_objects_index;
-
     VAddr wait_address; ///< If waiting on an AddressArbiter, this is the arbitration address
 
     /// True if the WaitSynchronizationN output parameter should be set on thread wakeup.

src/core/hle/svc.cpp

@@ -277,6 +277,7 @@ static ResultCode WaitSynchronization1(Kernel::Handle handle, s64 nano_seconds)
         if (nano_seconds == 0)
             return ERR_SYNC_TIMEOUT;
 
+        thread->wait_objects = {object};
         object->AddWaitingThread(thread);
         thread->status = THREADSTATUS_WAIT_SYNCH_ANY;
 
@@ -325,11 +326,6 @@ static ResultCode WaitSynchronizationN(s32* out, Kernel::Handle* handles, s32 ha
         objects[i] = object;
     }
 
-    // Clear the mapping of wait object indices.
-    // We don't want any lingering state in this map.
-    // It will be repopulated later in the wait_all = false case.
-    thread->wait_objects_index.clear();
-
     if (wait_all) {
         bool all_available =
             std::all_of(objects.begin(), objects.end(),
@@ -358,7 +354,6 @@ static ResultCode WaitSynchronizationN(s32* out, Kernel::Handle* handles, s32 ha
             object->AddWaitingThread(thread);
         }
 
-        // Set the thread's waitlist to the list of objects passed to WaitSynchronizationN
         thread->wait_objects = std::move(objects);
 
         // Create an event to wake the thread up after the specified nanosecond delay has passed
@@ -395,17 +390,14 @@ static ResultCode WaitSynchronizationN(s32* out, Kernel::Handle* handles, s32 ha
         // Put the thread to sleep
         thread->status = THREADSTATUS_WAIT_SYNCH_ANY;
 
-        // Clear the thread's waitlist, we won't use it for wait_all = false
-        thread->wait_objects.clear();
-
         // Add the thread to each of the objects' waiting threads.
         for (size_t i = 0; i < objects.size(); ++i) {
             Kernel::WaitObject* object = objects[i].get();
-            // Set the index of this object in the mapping of Objects -> index for this thread.
-            thread->wait_objects_index[object->GetObjectId()] = static_cast<int>(i);
             object->AddWaitingThread(thread);
         }
 
+        thread->wait_objects = std::move(objects);
+
         // Note: If no handles and no timeout were given, then the thread will deadlock, this is
         // consistent with hardware behavior.