using ARMeilleure.Diagnostics;
using ARMeilleure.Memory;
using ARMeilleure.Translation.PTC;
using System;
using System.Collections.Concurrent;
using System.Collections.Generic;
using System.Diagnostics;
using System.Runtime.InteropServices;
namespace ARMeilleure.Translation.Cache
{
class JumpTable : IDisposable
{
// The jump table is a block of (guestAddress, hostAddress) function mappings.
// Each entry corresponds to one branch in a JIT compiled function. The entries are
// reserved specifically for each call.
// The Dependants dictionary can be used to update the hostAddress for any functions that change.
public const int JumpTableStride = 16; // 8 byte guest address, 8 byte host address.
private const int JumpTableSize = 1048576;
private const int JumpTableByteSize = JumpTableSize * JumpTableStride;
// The dynamic table is also a block of (guestAddress, hostAddress) function mappings.
// The main difference is that indirect calls and jumps reserve _multiple_ entries on the table.
// These start out as all 0. When an indirect call is made, it tries to find the guest address on the table.
// If we get to an empty address, the guestAddress is set to the call that we want.
// If we get to a guestAddress that matches our own (or we just claimed it), the hostAddress is read.
// If it is non-zero, we immediately branch or call the host function.
// If it is 0, NativeInterface is called to find the rejited address of the call.
// If none is found, the hostAddress entry stays at 0. Otherwise, the new address is placed in the entry.
// If the table size is exhausted and we didn't find our desired address, we fall back to requesting
// the function from the JIT.
public const int DynamicTableElems = 1;
public const int DynamicTableStride = DynamicTableElems * JumpTableStride;
private const int DynamicTableSize = 1048576;
private const int DynamicTableByteSize = DynamicTableSize * DynamicTableStride;
public const int DynamicEntryTag = 1 << 31;
private readonly ReservedRegion _jumpRegion;
private readonly ReservedRegion _dynamicRegion;
public IntPtr JumpPointer => _jumpRegion.Pointer;
public IntPtr DynamicPointer => _dynamicRegion.Pointer;
public JumpTableEntryAllocator Table { get; }
public JumpTableEntryAllocator DynTable { get; }
public ConcurrentDictionary<ulong, TranslatedFunction> Targets { get; }
public ConcurrentDictionary<ulong, List<int>> Dependants { get; } // TODO: Attach to TranslatedFunction or a wrapper class.
public ConcurrentDictionary<ulong, List<int>> Owners { get; }
public JumpTable(IJitMemoryAllocator allocator)
{
_jumpRegion = new ReservedRegion(allocator, JumpTableByteSize);
_dynamicRegion = new ReservedRegion(allocator, DynamicTableByteSize);
Table = new JumpTableEntryAllocator();
DynTable = new JumpTableEntryAllocator();
Targets = new ConcurrentDictionary<ulong, TranslatedFunction>();
Dependants = new ConcurrentDictionary<ulong, List<int>>();
Owners = new ConcurrentDictionary<ulong, List<int>>();
Symbols.Add((ulong)_jumpRegion.Pointer.ToInt64(), JumpTableByteSize, JumpTableStride, "JMP_TABLE");
Symbols.Add((ulong)_dynamicRegion.Pointer.ToInt64(), DynamicTableByteSize, DynamicTableStride, "DYN_TABLE");
}
public void Initialize(PtcJumpTable ptcJumpTable, ConcurrentDictionary<ulong, TranslatedFunction> funcs)
{
foreach (ulong guestAddress in ptcJumpTable.Targets)
{
if (funcs.TryGetValue(guestAddress, out TranslatedFunction func))
{
Targets.TryAdd(guestAddress, func);
}
else
{
throw new KeyNotFoundException($"({nameof(guestAddress)} = 0x{guestAddress:X16})");
}
}
foreach (var kv in ptcJumpTable.Dependants)
{
Dependants.TryAdd(kv.Key, new List<int>(kv.Value));
}
foreach (var kv in ptcJumpTable.Owners)
{
Owners.TryAdd(kv.Key, new List<int>(kv.Value));
}
}
public void RegisterFunction(ulong address, TranslatedFunction func)
{
Targets.AddOrUpdate(address, func, (key, oldFunc) => func);
long funcPtr = func.FuncPtr.ToInt64();
// Update all jump table entries that target this address.
if (Dependants.TryGetValue(address, out List<int> myDependants))
{
lock (myDependants)
{
foreach (int entry in myDependants)
{
IntPtr addr = GetEntryAddressJumpTable(entry);
Marshal.WriteInt64(addr, 8, funcPtr);
}
}
}
}
public int ReserveTableEntry(ulong ownerGuestAddress, ulong address, bool isJump)
{
int entry = Table.AllocateEntry();
ExpandIfNeededJumpTable(entry);
// Is the address we have already registered? If so, put the function address in the jump table.
// If not, it will point to the direct call stub.
long value = DirectCallStubs.DirectCallStub(isJump).ToInt64();
if (Targets.TryGetValue(address, out TranslatedFunction func))
{
value = func.FuncPtr.ToInt64();
}
// Make sure changes to the function at the target address update this jump table entry.
List<int> targetDependants = Dependants.GetOrAdd(address, (addr) => new List<int>());
lock (targetDependants)
{
targetDependants.Add(entry);
}
// Keep track of ownership for jump table entries.
List<int> ownerEntries = Owners.GetOrAdd(ownerGuestAddress, (addr) => new List<int>());
lock (ownerEntries)
{
ownerEntries.Add(entry);
}
IntPtr addr = GetEntryAddressJumpTable(entry);
Marshal.WriteInt64(addr, 0, (long)address);
Marshal.WriteInt64(addr, 8, value);
return entry;
}
public int ReserveDynamicEntry(ulong ownerGuestAddress, bool isJump)
{
int entry = DynTable.AllocateEntry();
ExpandIfNeededDynamicTable(entry);
// Keep track of ownership for jump table entries.
List<int> ownerEntries = Owners.GetOrAdd(ownerGuestAddress, (addr) => new List<int>());
lock (ownerEntries)
{
ownerEntries.Add(entry | DynamicEntryTag);
}
// Initialize all host function pointers to the indirect call stub.
IntPtr addr = GetEntryAddressDynamicTable(entry);
long stubPtr = DirectCallStubs.IndirectCallStub(isJump).ToInt64();
for (int i = 0; i < DynamicTableElems; i++)
{
Marshal.WriteInt64(addr, i * JumpTableStride + 8, stubPtr);
}
return entry;
}
// For future use.
public void RemoveFunctionEntries(ulong guestAddress)
{
Targets.TryRemove(guestAddress, out _);
Dependants.TryRemove(guestAddress, out _);
if (Owners.TryRemove(guestAddress, out List<int> entries))
{
foreach (int entry in entries)
{
if ((entry & DynamicEntryTag) == 0)
{
IntPtr addr = GetEntryAddressJumpTable(entry);
Marshal.WriteInt64(addr, 0, 0L);
Marshal.WriteInt64(addr, 8, 0L);
Table.FreeEntry(entry);
}
else
{
IntPtr addr = GetEntryAddressDynamicTable(entry & ~DynamicEntryTag);
for (int j = 0; j < DynamicTableElems; j++)
{
Marshal.WriteInt64(addr + j * JumpTableStride, 0, 0L);
Marshal.WriteInt64(addr + j * JumpTableStride, 8, 0L);
}
DynTable.FreeEntry(entry & ~DynamicEntryTag);
}
}
}
}
public void ExpandIfNeededJumpTable(int entry)
{
Debug.Assert(entry >= 0);
if (entry < JumpTableSize)
{
_jumpRegion.ExpandIfNeeded((ulong)((entry + 1) * JumpTableStride));
}
else
{
throw new OutOfMemoryException("JIT Direct Jump Table exhausted.");
}
}
public void ExpandIfNeededDynamicTable(int entry)
{
Debug.Assert(entry >= 0);
if (entry < DynamicTableSize)
{
_dynamicRegion.ExpandIfNeeded((ulong)((entry + 1) * DynamicTableStride));
}
else
{
throw new OutOfMemoryException("JIT Dynamic Jump Table exhausted.");
}
}
public IntPtr GetEntryAddressJumpTable(int entry)
{
Debug.Assert(Table.EntryIsValid(entry));
return _jumpRegion.Pointer + entry * JumpTableStride;
}
public IntPtr GetEntryAddressDynamicTable(int entry)
{
Debug.Assert(DynTable.EntryIsValid(entry));
return _dynamicRegion.Pointer + entry * DynamicTableStride;
}
public bool CheckEntryFromAddressJumpTable(IntPtr entryAddress)
{
int entry = Math.DivRem((int)((ulong)entryAddress - (ulong)_jumpRegion.Pointer), JumpTableStride, out int rem);
return rem == 0 && Table.EntryIsValid(entry);
}
public bool CheckEntryFromAddressDynamicTable(IntPtr entryAddress)
{
int entry = Math.DivRem((int)((ulong)entryAddress - (ulong)_dynamicRegion.Pointer), DynamicTableStride, out int rem);
return rem == 0 && DynTable.EntryIsValid(entry);
}
public void Dispose()
{
_jumpRegion.Dispose();
_dynamicRegion.Dispose();
}
}
}