private bool TryOptimiseToXor(MatchResult matchResult, ILInstructionExpression expression)
{
var lefts = matchResult.Captures["left"];
var rights = matchResult.Captures["right"];
if (((ILVariableExpression)lefts[0]).Variable == ((ILVariableExpression)lefts[1]).Variable &&
((ILVariableExpression)rights[0]).Variable == ((ILVariableExpression)rights[1]).Variable)
{
// Unregister remaining variable references.
((ILVariableExpression)lefts[1]).Variable = null;
((ILVariableExpression)rights[1]).Variable = null;
// Replace with XOR pseudo opcode.
var newExpression = new ILInstructionExpression(
expression.OriginalOffset,
ILOpCodes.__XOR_DWORD,
null,
VMType.Dword);
newExpression.Arguments.Add((ILExpression)lefts[0].Parent.Remove());
newExpression.Arguments.Add((ILExpression)rights[0].Parent.Remove());
newExpression.FlagsVariable = expression.FlagsVariable;
expression.FlagsVariable = null;
expression.ReplaceWith(newExpression);
return(true);
}
return(false);
}
private bool TryOptimiseToSub(MatchResult matchResult, ILInstructionExpression expression)
{
var(left, right) = GetOperands(matchResult);
// Replace with SUB pseudo opcode.
var newExpression = new ILInstructionExpression(
expression.OriginalOffset,
ILOpCodes.__SUB_DWORD,
null,
VMType.Dword);
newExpression.Arguments.Add((ILExpression)left.Parent.Remove());
newExpression.Arguments.Add((ILExpression)right.Parent.Remove());
newExpression.FlagsVariable = expression.FlagsVariable;
expression.FlagsVariable = null;
expression.ReplaceWith(newExpression);
return(true);
}
public override bool VisitInstructionExpression(ILInstructionExpression expression)
{
// Any push expression that pushes the same type as its argument is superfluous.
bool changed = base.VisitInstructionExpression(expression);
var match = PushPattern.Match(expression);
if (match.Success)
{
var expr = (ILExpression)match.Captures["expr"][0];
if (expression.ExpressionType == expr.ExpressionType)
{
expression.ReplaceWith(expr.Remove());
changed = true;
}
}
return(changed);
}
private static bool TryOptimiseToNot(ILInstructionExpression expression, MatchResult matchResult)
{
var(left, right) = GetOperands(matchResult);
if (left.Variable == right.Variable)
{
// Unregister one of the variable uses.
right.Variable = null;
// Replace with NOT pseudo opcode.
var newExpression = new ILInstructionExpression(
expression.OriginalOffset,
ILOpCodes.__NOT_DWORD,
null,
VMType.Dword);
newExpression.Arguments.Add((ILExpression)left.Parent.Remove());
newExpression.FlagsVariable = expression.FlagsVariable;
expression.FlagsVariable = null;
expression.ReplaceWith(newExpression);
return(true);
}
return(false);
}
