private static void InjectAsyncStateMachineCheck(MethodDefinition method, TypeDefinition stateMachineType, WeavingContext weavingContext)
{
var bclReferences = weavingContext.BclReferences;
var moduleReferences = weavingContext.ModuleReferences;
if (!(GetMoveNextMethod(stateMachineType) is { } moveNextMethod))
{
WriteSkipWarning("'MoveNext' method not found.");
return;
}
var moveNextMethodBody = moveNextMethod.Body;
var instructions = moveNextMethodBody.Instructions;
if (!(GetSetResultMethodRef(instructions, out int index) is { } setResultMethodRef))
{
WriteSkipWarning("'SetResult' method not found.");
return;
}
if (!(GetSetExceptionMethodRef(setResultMethodRef.DeclaringType, bclReferences) is { } setExceptionMethodRef))
{
WriteSkipWarning("'SetException' method not found.");
return;
}
var resultType = ((GenericInstanceType)setResultMethodRef.DeclaringType).GenericArguments[0];
moveNextMethodBody.SimplifyMacros(); // For reliability just in case codegen is different and branches into this section of instructions exists
// Keep instruction that loads result value where is it so that branches stay pointed to it but insert another one that stays with the SetResult call.
var oldLoadResultInstruction = instructions[--index];
var newLoadResultInstruction = oldLoadResultInstruction.Clone();
instructions.Insert(++index, newLoadResultInstruction); // Don't increment index so this stays with the SetResult call
// Value on stack is the result value
ILHelpers.InsertGetValueRef(ref index, instructions, resultType);
const string message = "Async task result nullability contract was broken.";
ILHelpers.InsertThrowHelperCallIfValueRefIsNull(
ref index, instructions, moduleReferences.GetAsyncResultNullExceptionMethod, message, newLoadResultInstruction);
instructions.Insert(index++, Instruction.Create(OpCodes.Call, setExceptionMethodRef));
instructions.Insert(index++, Instruction.Create(OpCodes.Ret));
moveNextMethodBody.OptimizeMacros();
void WriteSkipWarning(string message) => weavingContext.WriteWarning($"Skipping async state machine result check on method '{method}': {message}");
}
private static void InjectIteratorStateMachineChecks(MethodDefinition method, TypeDefinition stateMachineType, WeavingContext weavingContext)
{
var moduleReferences = weavingContext.ModuleReferences;
if (!(GetMoveNextMethod(stateMachineType) is { } moveNextMethod))
{
WriteSkipWarning("'MoveNext' method not found on state machine.");
return;
}
if (!(GetFieldFromCurrentGetter(stateMachineType) is { } currentField))
{
WriteSkipWarning("'Current' getter with field reference not found.");
return;
}
var moveNextMethodBody = moveNextMethod.Body;
var instructions = moveNextMethodBody.Instructions;
moveNextMethodBody.SimplifyMacros();
for (int index = 1; index < instructions.Count; index++)
{
var instruction = instructions[index];
// Inject checks before all successful MoveNext operations.
if (instruction.OpCode == OpCodes.Ret && instruction.Previous.OpCode == OpCodes.Ldc_I4 && (int)instruction.Previous.Operand == 1)
{
index--;
instructions.Insert(index++, Instruction.Create(OpCodes.Ldarg_0));
instructions.Insert(index++, Instruction.Create(OpCodes.Ldfld, currentField));
ILHelpers.InsertGetValueRef(ref index, instructions, currentField.FieldType);
const string message = "Enumerator result nullability contract was broken.";
ILHelpers.InsertThrowHelperCallIfValueRefIsNull(
ref index, instructions, moduleReferences.ThrowOutputNullMethod, message, instructions[index]);
index += 2;
}
}
moveNextMethodBody.OptimizeMacros();
void WriteSkipWarning(string message) => weavingContext.WriteWarning($"Skipping iterator state machine result checks on method '{method}': {message}");
}
private static bool InjectSynchronousTaskResultCheck(MethodDefinition method, ReturnBlockInfo returnBlockInfo, WeavingContext weavingContext)
{
var bclReferences = weavingContext.BclReferences;
var moduleReferences = weavingContext.ModuleReferences;
var taskType = (GenericInstanceType)method.ReturnType;
var genericParameter = taskType.Resolve().GenericParameters[0];
var isCompletedGetter = new MethodReference("get_IsCompleted", bclReferences.BoolType, taskType)
{
HasThis = true
};
var isCanceledGetter = new MethodReference("get_IsCanceled", bclReferences.BoolType, taskType)
{
HasThis = true
};
var isFaultedGetter = new MethodReference("get_IsFaulted", bclReferences.BoolType, taskType)
{
HasThis = true
};
var resultGetter = new MethodReference("get_Result", genericParameter, taskType)
{
HasThis = true
};
if (isCompletedGetter.Resolve() == null)
{
WriteSkipWarning("'IsComplete' getter not found.");
return(false);
}
if (isCanceledGetter.Resolve() == null)
{
WriteSkipWarning("'IsCanceled' getter not found.");
return(false);
}
if (isFaultedGetter.Resolve() == null)
{
WriteSkipWarning("'IsFaulted' getter not found.");
return(false);
}
if (resultGetter.Resolve() == null)
{
WriteSkipWarning("'Result' getter not found.");
return(false);
}
var resultType = taskType.GenericArguments[0];
var instructions = method.Body.Instructions;
var returnBlockStartPoints = returnBlockInfo.NewStartPoints;
for (int i = 0; i < returnBlockStartPoints.Length; i++)
{
Instruction returnBlockStartPoint = returnBlockStartPoints[i];
int index = instructions.LastIndexOf(returnBlockStartPoint);
// Value on stack is the return task
var firstInstruction = Instruction.Create(OpCodes.Dup);
instructions.Insert(index++, firstInstruction);
instructions.Insert(index++, Instruction.Create(OpCodes.Call, isCompletedGetter));
instructions.Insert(index++, returnBlockInfo.CreateBranchInstruction(OpCodes.Brfalse_S, returnBlockStartPoint));
instructions.Insert(index++, Instruction.Create(OpCodes.Dup));
instructions.Insert(index++, Instruction.Create(OpCodes.Call, isCanceledGetter));
instructions.Insert(index++, returnBlockInfo.CreateBranchInstruction(OpCodes.Brtrue_S, returnBlockStartPoint));
instructions.Insert(index++, Instruction.Create(OpCodes.Dup));
instructions.Insert(index++, Instruction.Create(OpCodes.Call, isFaultedGetter));
instructions.Insert(index++, returnBlockInfo.CreateBranchInstruction(OpCodes.Brtrue_S, returnBlockStartPoint));
instructions.Insert(index++, Instruction.Create(OpCodes.Dup));
instructions.Insert(index++, Instruction.Create(OpCodes.Call, resultGetter));
ILHelpers.InsertGetValueRef(ref index, instructions, resultType);
const string message = "Task result nullability contract was broken.";
ILHelpers.InsertThrowHelperCallIfValueRefIsNull(
ref index, instructions, moduleReferences.ThrowOutputNullMethod, message, returnBlockStartPoint, returnBlockInfo);
returnBlockStartPoints[i] = firstInstruction;
}
return(true);
void WriteSkipWarning(string message) => weavingContext.WriteWarning($"Skipping synchronous task result check on method '{method}': {message}");
}
private static void InjectAsyncIteratorStateMachineChecks(MethodDefinition method, TypeDefinition stateMachineType, WeavingContext weavingContext)
{
var bclReferences = weavingContext.BclReferences;
var moduleReferences = weavingContext.ModuleReferences;
if (!(GetMoveNextMethod(stateMachineType) is { } moveNextMethod))
{
WriteSkipWarning("'MoveNext' method not found on state machine.");
return;
}
var moveNextMethodBody = moveNextMethod.Body;
var instructions = moveNextMethodBody.Instructions;
if (!(GetSetResultMethodRef(instructions, out int index) is { } setResultMethodRef))
{
WriteSkipWarning("'SetResult' method not found.");
return;
}
if (instructions[index - 1].OpCode != OpCodes.Ldc_I4_1)
{
WriteSkipWarning("Unexpected state machine implementation - 'SetResult' method argument was not true.");
return;
}
if (!(GetSetExceptionMethodRef(setResultMethodRef.DeclaringType, bclReferences) is { } setExceptionMethodRef))
{
WriteSkipWarning("'SetException' method not found.");
return;
}
if (!(GetFieldFromCurrentGetter(stateMachineType) is { } currentField))
{
WriteSkipWarning("'Current' getter with field reference not found.");
return;
}
moveNextMethodBody.SimplifyMacros(); // For reliability just in case codegen is different and branches into this section of instructions exists
// Go back one instruction to keep the argument for SetResult together with the call
var oldBlockStart = instructions[--index];
// Stack currently has the SetException/SetResult object on it
instructions.Insert(index++, Instruction.Create(OpCodes.Ldarg_0));
instructions.Insert(index++, Instruction.Create(OpCodes.Ldfld, currentField));
ILHelpers.InsertGetValueRef(ref index, instructions, currentField.FieldType);
const string message = "Async enumerator result nullability contract was broken.";
ILHelpers.InsertThrowHelperCallIfValueRefIsNull(
ref index, instructions, moduleReferences.GetAsyncResultNullExceptionMethod, message, oldBlockStart);
instructions.Insert(index++, Instruction.Create(OpCodes.Call, setExceptionMethodRef));
instructions.Insert(index++, Instruction.Create(OpCodes.Ret));
moveNextMethodBody.SimplifyMacros();
void WriteSkipWarning(string message) => weavingContext.WriteWarning($"Skipping async iterator state machine result checks on method '{method}': {message}");
}