private static void UpdateLocation(ref FMap <ILocalDefinition, Analysis.Instruction> currentLocals, ref FMap <IParameterDefinition, Analysis.Instruction> currentParameters, object localOrParameter, Analysis.Instruction newValue)
{
Contract.Requires(currentParameters != null);
Contract.Requires(currentLocals != null);
Contract.Ensures(Contract.ValueAtReturn(out currentParameters) != null);
Contract.Ensures(Contract.ValueAtReturn(out currentLocals) != null);
var local = localOrParameter as ILocalDefinition;
if (local != null)
{
currentLocals = currentLocals.Insert(local, newValue);
return;
}
var param = localOrParameter as IParameterDefinition;
if (param != null)
{
currentParameters = currentParameters.Insert(param, newValue);
return;
}
}
private static void ComputeDataFlowThroughLocals(ControlAndDataFlowGraph <BasicBlock, Instruction> cdg)
{
FMap <ILocalDefinition, Microsoft.Cci.Analysis.Instruction> currentLocals;
var todo = new Queue <BlockPC>();
var seen = new HashSet <BlockPC>();
var startBlock = cdg.RootBlocks[0];
FMap <IParameterDefinition, Microsoft.Cci.Analysis.Instruction> currentParameters = new FMap <IParameterDefinition, Microsoft.Cci.Analysis.Instruction>(k => k.Index);
var initialLocation = GetStartLocation(startBlock);
// push parameters onto start block
foreach (var arg in cdg.MethodBody.MethodDefinition.Parameters)
{
var initialOp = new InitialParameterAssignment(arg, initialLocation);
var initialDef = new Instruction()
{
Operation = initialOp
};
currentParameters = currentParameters.Insert(arg, initialDef);
}
startBlock.ParamDefs = currentParameters;
todo.Enqueue(new BlockPC(startBlock.Offset.Singleton()));
while (todo.Count > 0)
{
var currentPC = todo.Dequeue();
if (seen.Contains(currentPC))
{
continue;
}
seen.Add(currentPC);
var block = cdg.CurrentBlock(currentPC);
Contract.Assume(block != null);
currentLocals = block.LocalDefs;
currentParameters = block.ParamDefs;
foreach (var instr in block.Instructions)
{
if (instr.IsMergeNode)
{
continue;
}
switch (instr.Operation.OperationCode)
{
case OperationCode.Starg:
case OperationCode.Starg_S:
// without pdb we seem to have no parameter info.
var pdef = (IParameterDefinition)instr.Operation.Value;
if (pdef != null)
{
currentParameters = currentParameters.Insert(pdef, instr.Operand1);
}
break;
case OperationCode.Stloc:
case OperationCode.Stloc_0:
case OperationCode.Stloc_1:
case OperationCode.Stloc_2:
case OperationCode.Stloc_3:
case OperationCode.Stloc_S:
var ldef = (ILocalDefinition)instr.Operation.Value;
currentLocals = currentLocals.Insert(ldef, instr.Operand1);
break;
case OperationCode.Ldloc:
case OperationCode.Ldloc_0:
case OperationCode.Ldloc_1:
case OperationCode.Ldloc_2:
case OperationCode.Ldloc_3:
case OperationCode.Ldloc_S:
// save the source in Aux
{
currentLocals.TryGetValue((ILocalDefinition)instr.Operation.Value, out instr.Aux);
break;
}
case OperationCode.Ldarg:
case OperationCode.Ldarg_0:
case OperationCode.Ldarg_1:
case OperationCode.Ldarg_2:
case OperationCode.Ldarg_3:
case OperationCode.Ldarg_S:
// save the source in Aux
var pdef2 = (IParameterDefinition)instr.Operation.Value;
if (pdef2 == null)
{
// this parameter. Assume it's never overwritten
}
else
{
currentParameters.TryGetValue(pdef2, out instr.Aux);
}
break;
case OperationCode.Stind_I:
case OperationCode.Stind_I1:
case OperationCode.Stind_I2:
case OperationCode.Stind_I4:
case OperationCode.Stind_I8:
case OperationCode.Stind_R4:
case OperationCode.Stind_R8:
case OperationCode.Stind_Ref:
{
var location = cdg.LocalOrParameter(instr.Operand1);
UpdateLocation(ref currentLocals, ref currentParameters, location, (Analysis.Instruction)instr.Operand2);
break;
}
case OperationCode.Ldind_I:
case OperationCode.Ldind_I1:
case OperationCode.Ldind_I2:
case OperationCode.Ldind_I4:
case OperationCode.Ldind_I8:
case OperationCode.Ldind_R4:
case OperationCode.Ldind_R8:
case OperationCode.Ldind_Ref:
case OperationCode.Ldind_U1:
case OperationCode.Ldind_U2:
case OperationCode.Ldind_U4:
{
// save the read value in Aux
var location = cdg.LocalOrParameter(instr.Operand1);
instr.Aux = ReadLocation(currentLocals, currentParameters, location);
break;
}
case OperationCode.Call:
case OperationCode.Callvirt:
{
// update byref / out parameters
var methodRef = instr.Operation.Value as IMethodReference;
var args = instr.Operand2 as Instruction[];
if (args != null && methodRef != null)
{
foreach (var p in methodRef.Parameters)
{
if (p.IsByReference && p.Index < args.Length)
{
var arg = args[p.Index];
if (arg != null)
{
var loc = cdg.LocalOrParameter(arg);
var syntheticOp = new CallByRefAssignment(instr, p);
UpdateLocation(ref currentLocals, ref currentParameters, loc, new Instruction()
{
Operation = syntheticOp, Type = p.Type
});
}
}
}
}
break;
}
}
instr.PostLocalDefs = currentLocals;
instr.PostParamDefs = currentParameters;
}
foreach (var succ in cdg.Successors(currentPC))
{
MergeLocalsAndParameters(cdg.CurrentBlock(succ), currentLocals, currentParameters);
todo.Enqueue(succ);
}
}
}