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using ARMeilleure.Decoders;
using ARMeilleure.Instructions;
using ARMeilleure.IntermediateRepresentation;
using ARMeilleure.Memory;
using ARMeilleure.State;
using System.Collections.Generic;
using static ARMeilleure.IntermediateRepresentation.OperandHelper;
namespace ARMeilleure.Translation
{
class ArmEmitterContext : EmitterContext
{
private Dictionary<ulong, Operand> _labels;
private OpCode _optOpLastCompare;
private OpCode _optOpLastFlagSet;
private Operand _optCmpTempN;
private Operand _optCmpTempM;
private Block _currBlock;
public Block CurrBlock
{
get
{
return _currBlock;
}
set
{
_currBlock = value;
ResetBlockState();
}
}
public OpCode CurrOp { get; set; }
public MemoryManager Memory { get; }
public Aarch32Mode Mode { get; }
public ArmEmitterContext(MemoryManager memory, Aarch32Mode mode)
{
Memory = memory;
Mode = mode;
_labels = new Dictionary<ulong, Operand>();
}
public Operand GetLabel(ulong address)
{
if (!_labels.TryGetValue(address, out Operand label))
{
label = Label();
_labels.Add(address, label);
}
return label;
}
public void MarkComparison(Operand n, Operand m)
{
_optOpLastCompare = CurrOp;
_optCmpTempN = Copy(n);
_optCmpTempM = Copy(m);
}
public void MarkFlagSet(PState stateFlag)
{
// Set this only if any of the NZCV flag bits were modified.
// This is used to ensure that when emiting a direct IL branch
// instruction for compare + branch sequences, we're not expecting
// to use comparison values from an old instruction, when in fact
// the flags were already overwritten by another instruction further along.
if (stateFlag >= PState.VFlag)
{
_optOpLastFlagSet = CurrOp;
}
}
private void ResetBlockState()
{
_optOpLastCompare = null;
_optOpLastFlagSet = null;
}
public Operand TryGetComparisonResult(Condition condition)
{
if (_optOpLastCompare == null || _optOpLastCompare != _optOpLastFlagSet)
{
return null;
}
Operand n = _optCmpTempN;
Operand m = _optCmpTempM;
InstName cmpName = _optOpLastCompare.Instruction.Name;
if (cmpName == InstName.Subs)
{
switch (condition)
{
case Condition.Eq: return ICompareEqual (n, m);
case Condition.Ne: return ICompareNotEqual (n, m);
case Condition.GeUn: return ICompareGreaterOrEqualUI(n, m);
case Condition.LtUn: return ICompareLessUI (n, m);
case Condition.GtUn: return ICompareGreaterUI (n, m);
case Condition.LeUn: return ICompareLessOrEqualUI (n, m);
case Condition.Ge: return ICompareGreaterOrEqual (n, m);
case Condition.Lt: return ICompareLess (n, m);
case Condition.Gt: return ICompareGreater (n, m);
case Condition.Le: return ICompareLessOrEqual (n, m);
}
}
else if (cmpName == InstName.Adds && _optOpLastCompare is IOpCodeAluImm op)
{
// There are several limitations that needs to be taken into account for CMN comparisons:
// - The unsigned comparisons are not valid, as they depend on the
// carry flag value, and they will have different values for addition and
// subtraction. For addition, it's carry, and for subtraction, it's borrow.
// So, we need to make sure we're not doing a unsigned compare for the CMN case.
// - We can only do the optimization for the immediate variants,
// because when the second operand value is exactly INT_MIN, we can't
// negate the value as theres no positive counterpart.
// Such invalid values can't be encoded on the immediate encodings.
if (op.RegisterSize == RegisterSize.Int32)
{
m = Const((int)-op.Immediate);
}
else
{
m = Const(-op.Immediate);
}
switch (condition)
{
case Condition.Eq: return ICompareEqual (n, m);
case Condition.Ne: return ICompareNotEqual (n, m);
case Condition.Ge: return ICompareGreaterOrEqual(n, m);
case Condition.Lt: return ICompareLess (n, m);
case Condition.Gt: return ICompareGreater (n, m);
case Condition.Le: return ICompareLessOrEqual (n, m);
}
}
return null;
}
}
}
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