Kernel: Don't make a separate allocation for thread FPU state

We were allocating thread FPU state separately in order to ensure a
16-byte alignment. There should be no need to do that.

This patch makes it a regular value member of Thread instead, dodging
one heap allocation during thread creation.

Kernel/Thread.cpp

@@ -39,10 +39,6 @@ UNMAP_AFTER_INIT void Thread::initialize()
 
 KResultOr<NonnullRefPtr<Thread>> Thread::try_create(NonnullRefPtr<Process> process)
 {
-    auto fpu_state = try_make<FPUState>();
-    if (!fpu_state)
-        return ENOMEM;
-
     auto kernel_stack_region = MM.allocate_kernel_region(default_kernel_stack_size, {}, Region::Access::Read | Region::Access::Write, AllocationStrategy::AllocateNow);
     if (!kernel_stack_region)
         return ENOMEM;
@@ -54,17 +50,16 @@ KResultOr<NonnullRefPtr<Thread>> Thread::try_create(NonnullRefPtr<Process> proce
 
     auto name = KString::try_create(process->name());
 
-    auto thread = adopt_ref_if_nonnull(new (nothrow) Thread(move(process), kernel_stack_region.release_nonnull(), block_timer.release_nonnull(), fpu_state.release_nonnull(), move(name)));
+    auto thread = adopt_ref_if_nonnull(new (nothrow) Thread(move(process), kernel_stack_region.release_nonnull(), block_timer.release_nonnull(), move(name)));
     if (!thread)
         return ENOMEM;
 
     return thread.release_nonnull();
 }
 
-Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Region> kernel_stack_region, NonnullRefPtr<Timer> block_timer, NonnullOwnPtr<FPUState> fpu_state, OwnPtr<KString> name)
+Thread::Thread(NonnullRefPtr<Process> process, NonnullOwnPtr<Region> kernel_stack_region, NonnullRefPtr<Timer> block_timer, OwnPtr<KString> name)
     : m_process(move(process))
     , m_kernel_stack_region(move(kernel_stack_region))
-    , m_fpu_state(move(fpu_state))
     , m_name(move(name))
     , m_block_timer(block_timer)
     , m_global_procfs_inode_index(ProcFSComponentRegistry::the().allocate_inode_index())
@@ -1067,7 +1062,7 @@ RefPtr<Thread> Thread::clone(Process& process)
     auto signal_action_data_span = m_signal_action_data.span();
     signal_action_data_span.copy_to(clone->m_signal_action_data.span());
     clone->m_signal_mask = m_signal_mask;
-    memcpy(clone->m_fpu_state, m_fpu_state, sizeof(FPUState));
+    clone->m_fpu_state = m_fpu_state;
     clone->m_thread_specific_data = m_thread_specific_data;
     return clone;
 }
@@ -1267,7 +1262,7 @@ RefPtr<Thread> Thread::from_tid(ThreadID tid)
 
 void Thread::reset_fpu_state()
 {
-    memcpy(m_fpu_state, &Processor::current().clean_fpu_state(), sizeof(FPUState));
+    memcpy(&m_fpu_state, &Processor::current().clean_fpu_state(), sizeof(FPUState));
 }
 
 bool Thread::should_be_stopped() const

Kernel/Thread.h

@@ -1038,7 +1038,7 @@ public:
     u32 pending_signals() const;
     u32 pending_signals_for_state() const;
 
-    FPUState& fpu_state() { return *m_fpu_state; }
+    FPUState& fpu_state() { return m_fpu_state; }
 
     KResult make_thread_specific_region(Badge<Process>);
 
@@ -1215,7 +1215,7 @@ public:
     String backtrace();
 
 private:
-    Thread(NonnullRefPtr<Process>, NonnullOwnPtr<Region>, NonnullRefPtr<Timer>, NonnullOwnPtr<FPUState>, OwnPtr<KString>);
+    Thread(NonnullRefPtr<Process>, NonnullOwnPtr<Region>, NonnullRefPtr<Timer>, OwnPtr<KString>);
 
     IntrusiveListNode<Thread> m_process_thread_list_node;
     int m_runnable_priority { -1 };
@@ -1344,7 +1344,7 @@ private:
     unsigned m_ipv4_socket_read_bytes { 0 };
     unsigned m_ipv4_socket_write_bytes { 0 };
 
-    OwnPtr<FPUState> m_fpu_state;
+    FPUState m_fpu_state {};
     State m_state { Invalid };
     OwnPtr<KString> m_name;
     u32 m_priority { THREAD_PRIORITY_NORMAL };