private ExpressionSyntax GenCall(FuzzType type, bool allowNew)
{
Debug.Assert(!(type is RefType), "Cannot GenCall to ref type -- use GenExistingLValue for that");
FuncGenerator func;
if (allowNew && Random.FlipCoin(Options.GenNewMethodProb))
{
type = type ?? Types.PickType(Options.ReturnTypeIsByRefProb);
func = new FuncGenerator(_funcs, Random, Types, Statics, _genChecksumSiteId);
func.Generate(type, true);
}
else
{
IEnumerable <FuncGenerator> funcs = _funcs.Skip(_funcIndex + 1);
if (type != null)
{
funcs = funcs.Where(f => f.ReturnType.IsCastableTo(type) || (f.ReturnType is RefType rt && rt.InnerType.IsCastableTo(type)));
}
List <FuncGenerator> list = funcs.ToList();
if (list.Count == 0)
{
return(null);
}
func = Random.NextElement(list);
type = type ?? func.ReturnType;
}
ArgumentSyntax[] args = GenArgs(func, 0, out _);
InvocationExpressionSyntax invoc =
InvocationExpression(
IdentifierName(func.Name),
ArgumentList(
SeparatedList(args)));
if (func.ReturnType == type || func.ReturnType is RefType retRt && retRt.InnerType == type)
{
return(invoc);
}
return(CastExpression(type.GenReferenceTo(), invoc));
}
private ArgumentSyntax[] GenArgs(FuncGenerator funcToCall, int minRefEscapeScope, out int argsMinRefEscapeScope)
{
ArgumentSyntax[] args = new ArgumentSyntax[funcToCall.Parameters.Length];
argsMinRefEscapeScope = int.MaxValue;
for (int i = 0; i < args.Length; i++)
{
FuzzType paramType = funcToCall.Parameters[i].Type;
if (paramType is RefType rt)
{
LValueInfo lv = GenLValue(rt.InnerType, minRefEscapeScope);
argsMinRefEscapeScope = Math.Min(argsMinRefEscapeScope, lv.RefEscapeScope);
args[i] = Argument(lv.Expression).WithRefKindKeyword(Token(SyntaxKind.RefKeyword));
}
else
{
args[i] = Argument(GenExpression(paramType));
}
}
return(args);
}
private ExpressionSyntax GenCall(FuzzType type, bool allowNew)
{
Debug.Assert(!(type is RefType), "Cannot GenCall to ref type -- use GenExistingLValue for that");
FuncGenerator func;
if (allowNew && Random.FlipCoin(Options.GenNewFunctionProb) && !Options.FuncGenRejection.Reject(_funcs.Count, Random.Rng))
{
type = type ?? Types.PickType(Options.ReturnTypeIsByRefProb);
func = new FuncGenerator(_funcs, Random, Types, Statics, _genChecksumSiteId);
func.Generate(type, true);
}
else
{
IEnumerable <FuncGenerator> funcs =
_funcs
.Skip(_funcIndex + 1)
.Where(candidate =>
{
// Make sure we do not get too many leaf calls. Here we compute what the new transitive
// number of calls would be to each function, and if it's too much, reject this candidate.
// Note that we will never reject calling a leaf function directly, even if the +1 puts
// us over the cap. That is intentional. We only want to limit the exponential growth
// which happens when functions call functions multiple times, and those functions also
// call functions multiple times.
foreach (var(transFunc, transNumCall) in candidate._callCountMap)
{
_callCountMap.TryGetValue(transFunc, out long curNumCalls);
if (curNumCalls + transNumCall > Options.SingleFunctionMaxTotalCalls)
{
return(false);
}
}
return(true);
});
if (type != null)
{
funcs = funcs.Where(f => f.ReturnType.IsCastableTo(type) || (f.ReturnType is RefType rt && rt.InnerType.IsCastableTo(type)));
}
List <FuncGenerator> list = funcs.ToList();
if (list.Count == 0)
{
return(null);
}
func = Random.NextElement(list);
type = type ?? func.ReturnType;
}
// Update transitive call counts before generating args, so we decrease chance of
// calling the same methods in the arg expressions.
_callCountMap.TryGetValue(func._funcIndex, out long numCalls);
_callCountMap[func._funcIndex] = numCalls + 1;
foreach (var(transFunc, transNumCalls) in func._callCountMap)
{
_callCountMap.TryGetValue(transFunc, out long curNumCalls);
_callCountMap[transFunc] = curNumCalls + transNumCalls;
}
ArgumentSyntax[] args = GenArgs(func, 0, out _);
InvocationExpressionSyntax invoc =
InvocationExpression(
IdentifierName(func.Name),
ArgumentList(
SeparatedList(args)));
if (func.ReturnType == type || func.ReturnType is RefType retRt && retRt.InnerType == type)
{
return(invoc);
}
return(CastExpression(type.GenReferenceTo(), invoc));
}
private LValueInfo GenExistingLValue(FuzzType type, int minRefEscapeScope)
{
Debug.Assert(type == null || !(type is RefType));
LValueKind kind = (LValueKind)Options.ExistingLValueDist.Sample(Random.Rng);
if (kind == LValueKind.RefReturningCall)
{
List <FuncGenerator> refReturningFuncs = new List <FuncGenerator>();
foreach (FuncGenerator func in _funcs.Skip(_funcIndex + 1))
{
if (!(func.ReturnType is RefType rt))
{
continue;
}
if (type == null || type == rt.InnerType)
{
refReturningFuncs.Add(func);
}
}
// If we don't have a ref-returning function, fall back to local/static by retrying.
// The reason we don't always fall back to trying other options is that otherwise
// we may stack overflow in cases like ref int M(ref int a), if we have no locals
// or statics of type int. We would keep generating method calls in this case.
// This is kind of a hack, although it is pretty natural to pick statics/locals for
// lvalues, so it is not that big of a deal.
if (refReturningFuncs.Count == 0)
{
return(GenExistingLValue(type, minRefEscapeScope));
}
FuncGenerator funcToCall = Random.NextElement(refReturningFuncs);
// When calling a func that returns a by-ref, we need to take into account that the C# compiler
// performs 'escape-analysis' on by-refs. If we want to produce a non-local by-ref we are only
// allowed to pass non-local by-refs. The following example illustrates the analysis performed
// by the compiler:
// ref int M(ref int b, ref int c) {
// int a = 2;
// return ref Max(ref a, ref b); // compiler error, returned by-ref could point to 'a' and escape
// return ref Max(ref b, ref c); // ok, returned ref cannot point to local
// }
// ref int Max(ref int a, ref int b) { ... }
// This is the reason for the second arg passed to GenArgs. For example, if we want a call to return
// a ref that may escape, we need a minimum ref escape scope of 1, since 0 could pass refs to locals,
// and the result of that call would not be valid to return.
ArgumentSyntax[] args = GenArgs(funcToCall, minRefEscapeScope, out int argsMinRefEscapeScope);
InvocationExpressionSyntax invoc =
InvocationExpression(
IdentifierName(funcToCall.Name),
ArgumentList(
SeparatedList(
args)));
return(new LValueInfo(invoc, ((RefType)funcToCall.ReturnType).InnerType, argsMinRefEscapeScope));
}
List <LValueInfo> lvalues = CollectVariablePaths(type, minRefEscapeScope, kind == LValueKind.Local, kind == LValueKind.Static);
if (lvalues.Count == 0)
{
// We typically fall back to generating a static, so just try to find a static if we found no local.
if (kind != LValueKind.Local)
{
return(null);
}
lvalues = CollectVariablePaths(type, minRefEscapeScope, false, true);
if (lvalues.Count == 0)
{
return(null);
}
}
return(Random.NextElement(lvalues));
}
internal void GenerateMethods(Func <string> genChecksumSiteId)
{
FuncGenerator gen = new FuncGenerator(_funcs, Random, Types, Statics, genChecksumSiteId);
gen.Generate(null, false);
}