private BoundExpression MakePropertyAssignment(
SyntaxNode syntax,
BoundExpression rewrittenReceiver,
PropertySymbol property,
ImmutableArray <BoundExpression> rewrittenArguments,
ImmutableArray <RefKind> argumentRefKindsOpt,
bool expanded,
ImmutableArray <int> argsToParamsOpt,
BoundExpression rewrittenRight,
TypeSymbol type,
bool used)
{
// Rewrite property assignment into call to setter.
var setMethod = property.GetOwnOrInheritedSetMethod();
if ((object)setMethod == null)
{
Debug.Assert((property as SourcePropertySymbol)?.IsAutoProperty == true,
"only autoproperties can be assignable without having setters");
var backingField = (property as SourcePropertySymbol).BackingField;
return(_factory.AssignmentExpression(
_factory.Field(rewrittenReceiver, backingField),
rewrittenRight));
}
// We have already lowered each argument, but we may need some additional rewriting for the arguments,
// such as generating a params array, re-ordering arguments based on argsToParamsOpt map, inserting arguments for optional parameters, etc.
ImmutableArray <LocalSymbol> argTemps;
rewrittenArguments = MakeArguments(
syntax,
rewrittenArguments,
property,
setMethod,
expanded,
argsToParamsOpt,
ref argumentRefKindsOpt,
out argTemps,
invokedAsExtensionMethod: false,
enableCallerInfo: ThreeState.True);
if (used)
{
// Save expression value to a temporary before calling the
// setter, and restore the temporary after the setter, so the
// assignment can be used as an embedded expression.
TypeSymbol exprType = rewrittenRight.Type;
LocalSymbol rhsTemp = _factory.SynthesizedLocal(exprType);
BoundExpression boundRhs = new BoundLocal(syntax, rhsTemp, null, exprType);
BoundExpression rhsAssignment = new BoundAssignmentOperator(
syntax,
boundRhs,
rewrittenRight,
exprType);
BoundExpression setterCall = BoundCall.Synthesized(
syntax,
rewrittenReceiver,
setMethod,
AppendToPossibleNull(rewrittenArguments, rhsAssignment));
return(new BoundSequence(
syntax,
AppendToPossibleNull(argTemps, rhsTemp),
ImmutableArray.Create(setterCall),
boundRhs,
type));
}
else
{
BoundCall setterCall = BoundCall.Synthesized(
syntax,
rewrittenReceiver,
setMethod,
AppendToPossibleNull(rewrittenArguments, rewrittenRight));
if (argTemps.IsDefaultOrEmpty)
{
return(setterCall);
}
else
{
return(new BoundSequence(
syntax,
argTemps,
ImmutableArray <BoundExpression> .Empty,
setterCall,
setMethod.ReturnType));
}
}
}
private BoundIndexerAccess TransformIndexerAccess(BoundIndexerAccess indexerAccess, ArrayBuilder <BoundExpression> stores, ArrayBuilder <LocalSymbol> temps)
{
var receiverOpt = indexerAccess.ReceiverOpt;
Debug.Assert(receiverOpt != null);
BoundExpression transformedReceiver;
if (CanChangeValueBetweenReads(receiverOpt))
{
BoundExpression rewrittenReceiver = VisitExpression(receiverOpt);
BoundAssignmentOperator assignmentToTemp;
// SPEC VIOLATION: It is not very clear when receiver of constrained callvirt is dereferenced - when pushed (in lexical order),
// SPEC VIOLATION: or when actual call is executed. The actual behavior seems to be implementation specific in different JITs.
// SPEC VIOLATION: To not depend on that, the right thing to do here is to store the value of the variable
// SPEC VIOLATION: when variable has reference type (regular temp), and store variable's location when it has a value type. (ref temp)
// SPEC VIOLATION: in a case of unconstrained generic type parameter a runtime test (default(T) == null) would be needed
// SPEC VIOLATION: However, for compatibility with Dev12 we will continue treating all generic type parameters, constrained or not,
// SPEC VIOLATION: as value types.
var variableRepresentsLocation = rewrittenReceiver.Type.IsValueType || rewrittenReceiver.Type.Kind == SymbolKind.TypeParameter;
var receiverTemp = _factory.StoreToTemp(rewrittenReceiver, out assignmentToTemp, refKind: variableRepresentsLocation ? RefKind.Ref : RefKind.None);
transformedReceiver = receiverTemp;
stores.Add(assignmentToTemp);
temps.Add(receiverTemp.LocalSymbol);
}
else
{
transformedReceiver = VisitExpression(receiverOpt);
}
// Dealing with the arguments is a bit tricky because they can be named out-of-order arguments;
// we have to preserve both the source-code order of the side effects and the side effects
// only being executed once.
//
// This is a subtly different problem than the problem faced by the conventional call
// rewriter; with the conventional call rewriter we already know that the side effects
// will only be executed once because the arguments are only being pushed on the stack once.
// In a compound equality operator on an indexer the indices are placed on the stack twice.
// That is to say, if you have:
//
// C().M(z : Z(), x : X(), y : Y())
//
// then we can rewrite that into
//
// tempc = C()
// tempz = Z()
// tempc.M(X(), Y(), tempz)
//
// See, we can optimize away two of the temporaries, for x and y. But we cannot optimize away any of the
// temporaries in
//
// C().Collection[z : Z(), x : X(), y : Y()] += 1;
//
// because we have to ensure not just that Z() happens first, but in addition that X() and Y() are only
// called once. We have to generate this as
//
// tempc = C().Collection
// tempz = Z()
// tempx = X()
// tempy = Y()
// tempc[tempx, tempy, tempz] = tempc[tempx, tempy, tempz] + 1;
//
// Fortunately arguments to indexers are never ref or out, so we don't need to worry about that.
// However, we can still do the optimization where constants are not stored in
// temporaries; if we have
//
// C().Collection[z : 123, y : Y(), x : X()] += 1;
//
// Then we can generate that as
//
// tempc = C().Collection
// tempx = X()
// tempy = Y()
// tempc[tempx, tempy, 123] = tempc[tempx, tempy, 123] + 1;
ImmutableArray <BoundExpression> rewrittenArguments = VisitList(indexerAccess.Arguments);
SyntaxNode syntax = indexerAccess.Syntax;
PropertySymbol indexer = indexerAccess.Indexer;
ImmutableArray <RefKind> argumentRefKinds = indexerAccess.ArgumentRefKindsOpt;
bool expanded = indexerAccess.Expanded;
ImmutableArray <int> argsToParamsOpt = indexerAccess.ArgsToParamsOpt;
ImmutableArray <ParameterSymbol> parameters = indexer.Parameters;
BoundExpression[] actualArguments = new BoundExpression[parameters.Length]; // The actual arguments that will be passed; one actual argument per formal parameter.
ArrayBuilder <BoundAssignmentOperator> storesToTemps = ArrayBuilder <BoundAssignmentOperator> .GetInstance(rewrittenArguments.Length);
ArrayBuilder <RefKind> refKinds = ArrayBuilder <RefKind> .GetInstance(parameters.Length, RefKind.None);
// Step one: Store everything that is non-trivial into a temporary; record the
// stores in storesToTemps and make the actual argument a reference to the temp.
// Do not yet attempt to deal with params arrays or optional arguments.
BuildStoresToTemps(
expanded,
argsToParamsOpt,
parameters,
argumentRefKinds,
rewrittenArguments,
forceLambdaSpilling: true, // lambdas must produce exactly one delegate so they must be spilled into a temp
actualArguments,
refKinds,
storesToTemps);
// Step two: If we have a params array, build the array and fill in the argument.
if (expanded)
{
BoundExpression array = BuildParamsArray(syntax, indexer, argsToParamsOpt, rewrittenArguments, parameters, actualArguments[actualArguments.Length - 1]);
BoundAssignmentOperator storeToTemp;
var boundTemp = _factory.StoreToTemp(array, out storeToTemp);
stores.Add(storeToTemp);
temps.Add(boundTemp.LocalSymbol);
actualArguments[actualArguments.Length - 1] = boundTemp;
}
// Step three: Now fill in the optional arguments. (Dev11 uses the getter for optional arguments in
// compound assignments, but for deconstructions we use the setter if the getter is missing.)
var accessor = indexer.GetOwnOrInheritedGetMethod() ?? indexer.GetOwnOrInheritedSetMethod();
InsertMissingOptionalArguments(syntax, accessor.Parameters, actualArguments, refKinds);
// For a call, step four would be to optimize away some of the temps. However, we need them all to prevent
// duplicate side-effects, so we'll skip that step.
if (indexer.ContainingType.IsComImport)
{
RewriteArgumentsForComCall(parameters, actualArguments, refKinds, temps);
}
rewrittenArguments = actualArguments.AsImmutableOrNull();
foreach (BoundAssignmentOperator tempAssignment in storesToTemps)
{
temps.Add(((BoundLocal)tempAssignment.Left).LocalSymbol);
stores.Add(tempAssignment);
}
storesToTemps.Free();
argumentRefKinds = GetRefKindsOrNull(refKinds);
refKinds.Free();
// This is a temporary object that will be rewritten away before the lowering completes.
return(new BoundIndexerAccess(
syntax,
transformedReceiver,
indexer,
rewrittenArguments,
default(ImmutableArray <string>),
argumentRefKinds,
false,
default(ImmutableArray <int>),
null,
indexerAccess.UseSetterForDefaultArgumentGeneration,
indexerAccess.Type));
}
