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;
}
private static bool CheckCeqInstruction (Instruction instruction, MethodDefinition method)
{
bool problem = false;
switch (instruction.OpCode.Code) {
case Code.Conv_R_Un:
case Code.Conv_R4:
case Code.Conv_R8:
return true;
case Code.Ldc_R4:
return !CheckFloatConstants ((float) instruction.Operand);
case Code.Ldc_R8:
return !CheckDoubleConstants ((double) instruction.Operand);
case Code.Ldelem_R4:
case Code.Ldelem_R8:
return true;
case Code.Ldloc_0:
case Code.Ldloc_1:
case Code.Ldloc_2:
case Code.Ldloc_3:
case Code.Ldloc_S:
case Code.Ldloc:
case Code.Ldloca:
case Code.Ldloca_S:
return instruction.GetVariable (method).VariableType.IsFloatingPoint ();
case Code.Ldarg_0:
case Code.Ldarg_1:
case Code.Ldarg_2:
case Code.Ldarg_3:
case Code.Ldarg:
case Code.Ldarg_S:
case Code.Ldarga:
case Code.Ldarga_S:
ParameterDefinition parameter = instruction.GetParameter (method);
// handle 'this'
if (parameter == null)
return method.DeclaringType.IsFloatingPoint ();
return parameter.ParameterType.IsFloatingPoint ();
case Code.Call:
case Code.Callvirt:
MethodReference call = instruction.Operand as MethodReference;
return call.ReturnType.IsFloatingPoint ();
case Code.Ldfld:
case Code.Ldflda:
case Code.Ldsfld:
case Code.Ldsflda:
FieldReference field = instruction.Operand as FieldReference;
return field.FieldType.IsFloatingPoint ();
}
return problem;
}
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 AreMirrorInstructions (Instruction ld, Instruction st, MethodDefinition method)
{
return (ld.GetVariable (method).Index == st.GetVariable (method).Index);
}
// true == handled
// false == unhandled
bool CheckIfStored (Instruction afterLdstr)
{
switch (afterLdstr.OpCode.Code) {
case Code.Stfld: // store into field
case Code.Stsfld:
CheckIdentifier ((afterLdstr.Operand as FieldReference).Name);
break;
default:
if (afterLdstr.IsStoreLocal ())
CheckIdentifier (afterLdstr.GetVariable (method_body.Method).Name);
else
return false;
break;
}
return true; // handled
}
static string CheckDoubleAssignementOnInstanceFields (MethodDefinition method, Instruction ins, Instruction next)
{
// for an instance fiels the pattern is more complex because we must check that we're assigning to the same instance
// first we go forward: DUP, STLOC, STFLD, LDLOC, STFLD
Instruction load = next.Next;
if ((load == null) || !load.IsLoadLocal ())
return String.Empty;
// check that this is the same variable
VariableDefinition vd1 = ins.GetVariable (method);
VariableDefinition vd2 = load.GetVariable (method);
if (vd1.Index != vd2.Index)
return String.Empty;
Instruction stfld = load.Next;
if ((stfld == null) || (stfld.OpCode.Code != Code.Stfld))
return String.Empty;
// check that we're assigning the same field twice
FieldReference fd1 = (next.Operand as FieldReference);
FieldReference fd2 = (stfld.Operand as FieldReference);
if (fd1.MetadataToken.RID != fd2.MetadataToken.RID)
return String.Empty;
// backward: DUP, (possible CONV), LD (value to be duplicated), LD instance, LD instance
if (stfld.TraceBack (method).GetOperand (method) != next.TraceBack (method).GetOperand (method))
return String.Empty;
return String.Format ("Instance field '{0}' on same variable '{1}'.", fd1.Name, vd1.Name);
}
static string CheckDoubleAssignement (MethodDefinition method, Instruction ins, Instruction next)
{
// for a static field the pattern is
// DUP, STSFLD, STSFLD
if (ins.OpCode.Code == Code.Stsfld) {
if (next.OpCode.Code != Code.Stsfld)
return String.Empty;
// check that we're assigning the same field twice
FieldDefinition fd1 = ins.GetField ();
FieldDefinition fd2 = next.GetField ();
if (fd1.MetadataToken.RID != fd2.MetadataToken.RID)
return String.Empty;
return String.Format ("Static field '{0}'.", fd1.Name);
} else if (ins.IsStoreLocal ()) {
// for a local variable the pattern is
// DUP, STLOC, STLOC
VariableDefinition vd2 = next.GetVariable (method);
// check that we're assigning the same variable twice
if (vd2 != null) {
VariableDefinition vd1 = ins.GetVariable (method);
if (vd1.Index != vd2.Index)
return String.Empty;
return String.Format ("Local variable '{0}'.", vd1.Name);
} else if (next.OpCode.Code == Code.Stfld) {
// instance fields are a bit more complex...
return CheckDoubleAssignementOnInstanceFields (method, ins, next);
}
}
return String.Empty;
}
void CheckReassignment (MethodDefinition method, Instruction ins)
{
VariableDefinition v = ins.GetVariable (method);
ulong index = (ulong) v.Index;
if (locals.Get (index)) {
string msg = String.Format (CultureInfo.InvariantCulture,
"Local {0}is not disposed before being re-assigned.",
GetFriendlyNameOrEmpty (v));
Runner.Report (method, ins, Severity.High, Confidence.Normal, msg);
} else {
locals.Set (index);
}
}
void Clear (MethodDefinition method, Instruction ins)
{
VariableDefinition v = ins.GetVariable (method);
if (v != null)
locals.Clear ((ulong) v.Index);
}
Instruction FindRelatedSuspectLocal (MethodDefinition method, Instruction ins)
{
ins = LocalTraceBack (method, ins);
if (null == ins)
return null;
int index = ins.GetVariable (method).Index;
foreach (var local in suspectLocals) {
if (local.GetVariable (method).Index == index)
return local;
}
return null;
}