private static void EmitNativeCall(ArmEmitterContext context, Operand nativeContextPtr, Operand funcAddr, bool isJump = false)
{
context.StoreToContext();
if (isJump)
{
context.Tailcall(funcAddr, nativeContextPtr);
}
else
{
OpCode op = context.CurrOp;
Operand returnAddress = context.Call(funcAddr, OperandType.I64, nativeContextPtr);
context.LoadFromContext();
// Note: The return value of a translated function is always an Int64 with the address execution has
// returned to. We expect this address to be immediately after the current instruction, if it isn't we
// keep returning until we reach the dispatcher.
Operand nextAddr = Const((long)op.Address + op.OpCodeSizeInBytes);
// Try to continue within this block.
// If the return address isn't to our next instruction, we need to return so the JIT can figure out
// what to do.
Operand lblContinue = context.GetLabel(nextAddr.Value);
// We need to clear out the call flag for the return address before comparing it.
context.BranchIf(lblContinue, context.BitwiseAnd(returnAddress, Const(~CallFlag)), nextAddr, Comparison.Equal);
context.Return(returnAddress);
}
}
private static void EmitTableBranch(ArmEmitterContext context, Operand guestAddress, bool isJump)
{
context.StoreToContext();
if (guestAddress.Type == OperandType.I32)
{
guestAddress = context.ZeroExtend32(OperandType.I64, guestAddress);
}
// Store the target guest address into the native context. The stubs uses this address to dispatch into the
// next translation.
Operand nativeContext = context.LoadArgument(OperandType.I64, 0);
Operand dispAddressAddr = context.Add(nativeContext, Const((ulong)NativeContext.GetDispatchAddressOffset()));
context.Store(dispAddressAddr, guestAddress);
Operand hostAddress;
// If address is mapped onto the function table, we can skip the table walk. Otherwise we fallback
// onto the dispatch stub.
if (guestAddress.Kind == OperandKind.Constant && context.FunctionTable.IsValid(guestAddress.Value))
{
Operand hostAddressAddr = !context.HasPtc ?
Const(ref context.FunctionTable.GetValue(guestAddress.Value)) :
Const(ref context.FunctionTable.GetValue(guestAddress.Value), new Symbol(SymbolType.FunctionTable, guestAddress.Value));
hostAddress = context.Load(OperandType.I64, hostAddressAddr);
}
else
{
hostAddress = !context.HasPtc ?
Const((long)context.Stubs.DispatchStub) :
Const((long)context.Stubs.DispatchStub, Ptc.DispatchStubSymbol);
}
if (isJump)
{
context.Tailcall(hostAddress, nativeContext);
}
else
{
OpCode op = context.CurrOp;
Operand returnAddress = context.Call(hostAddress, OperandType.I64, nativeContext);
context.LoadFromContext();
// Note: The return value of a translated function is always an Int64 with the address execution has
// returned to. We expect this address to be immediately after the current instruction, if it isn't we
// keep returning until we reach the dispatcher.
Operand nextAddr = Const((long)op.Address + op.OpCodeSizeInBytes);
// Try to continue within this block.
// If the return address isn't to our next instruction, we need to return so the JIT can figure out
// what to do.
Operand lblContinue = context.GetLabel(nextAddr.Value);
context.BranchIf(lblContinue, returnAddress, nextAddr, Comparison.Equal, BasicBlockFrequency.Cold);
context.Return(returnAddress);
}
}