internal static bool AreEquivalent(Instruction source, Instruction target)
{
if (source.OpCode.Code != target.OpCode.Code)
return false;
if (source.OpCode.Code == Code.Ldstr)
return true;
//Check the types in ldarg stuff. Sometimes this scheme
//could lead us to false positives. We need an analysis
//which depends on the context.
if (source.IsLoadArgument ()) {
// case where 'ldarg this' is used (p.GetSequence () would be 0)
if (!Current.HasParameters && !Target.HasParameters)
return true;
return AreEquivalent (source.GetParameter (Current), target.GetParameter (Target));
}
// The same for ldloc / stloc
if (source.IsLoadLocal () || source.IsStoreLocal ())
return AreEquivalent (source.GetVariable (Current), target.GetVariable (Target));
//WARNING: Dirty Evil Hack: this should be in the
//Pattern class
if (source.OpCode.Code == Code.Ret && source.Previous != null &&
(source.Previous.OpCode.StackBehaviourPush == StackBehaviour.Pushi ||
source.Previous.OpCode.Code == Code.Ldnull ||
source.Previous.OpCode.StackBehaviourPush == StackBehaviour.Push1))
return false;
//if (source.Operand != target.Operand)
if (source.Operand != null && target.Operand != null) {
// we're sure that target.Operand is of the same type as source.Operand (same OpCode is used)
Instruction si = (source.Operand as Instruction);
if (si != null)
return (si.Offset == ((Instruction) target.Operand).Offset);
IMetadataTokenProvider sm = (source.Operand as IMetadataTokenProvider);
if (sm != null)
return sm.Equals (target.Operand as IMetadataTokenProvider);
if (source.Operand == target.Operand)
return true;
// last chance: we do call ToString
if (source.Operand.ToString () != target.Operand.ToString ())
return false;
}
return true;
}
static bool OriginsMatch (MethodDefinition method, Instruction lhs, Instruction rhs)
{
bool match = false;
object operand1 = lhs.GetOperand (method);
object operand2 = rhs.GetOperand (method);
if (lhs.OpCode.Code == rhs.OpCode.Code) {
if (lhs.IsLoadArgument ())
match = operand1.Equals (operand2);
else if (lhs.IsLoadElement ())
match = LoadElementMatch (method, lhs, rhs);
else if (lhs.IsLoadIndirect ())
match = LoadIndirectMatch (method, lhs, rhs);
else if (lhs.IsLoadLocal ())
match = LocalsMatch (operand1, operand2);
} else if (lhs.IsStoreLocal () && rhs.IsLoadLocal ())
match = LocalsMatch (operand1, operand2);
else if (lhs.IsLoadLocal () && rhs.IsStoreLocal ())
match = LocalsMatch (operand1, operand2);
return match;
}
private static Instruction StoreLoadLocal (MethodDefinition method, Instruction ins)
{
// check for a STLOC followed by a LDLOC
if (!ins.IsLoadLocal () || !ins.Previous.IsStoreLocal ())
return null;
// make sure it's about the same local variable
if (ins.GetVariable (method) != ins.Previous.GetVariable (method))
return null;
return ins.Previous.Previous;
}
private static bool CheckParameters (MethodDefinition method, Instruction ins)
{
Instruction prev;
if (ins.IsLoadLocal ()) {
prev = ins.Previous;
while (null != prev) {
// look for a STLOC* instruction and compare the variable indexes
if (prev.IsStoreLocal () && AreMirrorInstructions (ins, prev, method))
return IsGetNow (prev.Previous);
prev = prev.Previous;
}
} else if (ins.OpCode.Code == Code.Ldobj) {
prev = ins.TraceBack (method);
ParameterDefinition p = prev.GetParameter (method);
if (p == null)
return false;
int arg = p.GetSequence ();
prev = prev.Previous;
while (null != prev) {
// look for a STOBJ instruction and compare the objects
if (prev.OpCode.Code == Code.Stobj) {
prev = prev.TraceBack (method);
p = prev.GetParameter (method);
return (p == null) ? false : (arg == p.GetSequence ());
}
prev = prev.Previous;
}
} else {
return IsGetNow (ins);
}
return false;
}
void CheckForOutParameters (MethodDefinition method, Instruction ins)
{
Instruction iref = ins.TraceBack (method);
if (iref == null)
return;
ParameterDefinition p = iref.GetParameter (method);
if ((p != null) && p.IsOut) {
ins = ins.Previous;
if (ins.IsLoadLocal ())
Clear (method, ins);
}
}
void CheckForReturn (MethodDefinition method, Instruction ins)
{
if (ins.IsLoadLocal ())
Clear (method, ins);
}
private void Apply(Instruction instruction, Stack<Value> stack, ICollection<Value> values, IList<Value> locals)
{
// TODO: this method is a mess and needs to be refactored!!
var pushCount = instruction.GetPushCount();
var popCount = instruction.GetPopCount(_method);
if (popCount == Int32.MaxValue)
popCount = stack.Count;
var isCall = instruction.OpCode.FlowControl == FlowControl.Call;
var callParams = isCall ? (instruction.Operand as MethodReference).Parameters : NoParams;
// List of all popped values
var poppedValues = new List<Value>();
var inputArguments = new List<Value>();
for (var i = 0; i < popCount; i++)
{
// Instruction is a consumer
var value = stack.Pop();
poppedValues.Add(value);
// If we popped a value for an out parameter, we're not a consumer!
// Note that the first pop returns the last argument.
if (isCall && i < callParams.Count && callParams[callParams.Count - i - 1].IsOut)
{
inputArguments.Insert(0, null); // empty slot
continue;
}
value.Consumer = instruction;
inputArguments.Insert(0, value); //TODO: not 'this'!?!?
}
int storeIndex;
if (instruction.IsStoreLocal(out storeIndex))
{
Debug.Assert(popCount == 1);
locals[storeIndex] = poppedValues[0];
}
for (var i = 0; i < pushCount; i++)
{
Value newValue;
// Instruction is a producer
int loadIndex;
if (instruction.IsLoadLocal(out loadIndex))
{
Debug.Assert(pushCount == 1);
newValue = new Value(instruction);
values.Add(newValue);
// The local value can be null if we're passing loading a reference
// destined for an out parameter. Note that we can get a non-null
// value as well, so we have to sort things out when we handle the
// call to the method with the out parameter.
var localValue = locals[loadIndex];
if (localValue != null)
{
newValue.AddParents(new[] { localValue });
}
}
else
{
newValue = new Value(instruction);
values.Add(newValue);
newValue.AddParents(inputArguments.Where(a => a != null));
}
stack.Push(newValue);
}
if (isCall)
{
var argValues = new Value[callParams.Count];
for (var i = 0; i < argValues.Length; i++)
{
argValues[i] = poppedValues[argValues.Length - i - 1];
}
for (var i = 0; i < callParams.Count; i++)
{
// First of poppedValues is last argument
var inputArgument = poppedValues[callParams.Count - i - 1];
if (!callParams[i].IsRef() && !callParams[i].IsOut)
continue;
var newValue = new Value(instruction);
var storeAtIndex = (inputArgument.Producer.Operand as VariableDefinition).Index;
// Add all input values (including any refs) as parents!
for (var j = 0; j < callParams.Count; j++)
{
if (callParams[j].IsOut)
continue;
newValue.AddParents(new[] { argValues[j] });
}
// Don't push onto the stack, but save the value and store
// it in the locals array.
values.Add(newValue);
locals[storeAtIndex] = newValue;
}
}
}
static Instruction LocalTraceBack (IMethodSignature method, Instruction ins)
{
ins = ins.TraceBack (method);
while (ins != null) {
if (ins.IsLoadLocal () || ins.IsStoreLocal ())
return ins;
ins = ins.TraceBack (method);
}
return null;
}
