private BoundDynamicIndexerAccess TransformDynamicIndexerAccess(BoundDynamicIndexerAccess indexerAccess, ArrayBuilder <BoundExpression> stores, ArrayBuilder <LocalSymbol> temps)
{
BoundExpression loweredReceiver;
if (CanChangeValueBetweenReads(indexerAccess.ReceiverOpt))
{
BoundAssignmentOperator assignmentToTemp;
var temp = _factory.StoreToTemp(VisitExpression(indexerAccess.ReceiverOpt), out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredReceiver = temp;
}
else
{
loweredReceiver = indexerAccess.ReceiverOpt;
}
var arguments = indexerAccess.Arguments;
var loweredArguments = new BoundExpression[arguments.Length];
for (int i = 0; i < arguments.Length; i++)
{
if (CanChangeValueBetweenReads(arguments[i]))
{
BoundAssignmentOperator assignmentToTemp;
var temp = _factory.StoreToTemp(VisitExpression(arguments[i]), out assignmentToTemp, indexerAccess.ArgumentRefKindsOpt.RefKinds(i) != RefKind.None ? RefKind.Ref : RefKind.None);
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredArguments[i] = temp;
}
else
{
loweredArguments[i] = arguments[i];
}
}
return(new BoundDynamicIndexerAccess(
indexerAccess.Syntax,
loweredReceiver,
loweredArguments.AsImmutableOrNull(),
indexerAccess.ArgumentNamesOpt,
indexerAccess.ArgumentRefKindsOpt,
indexerAccess.ApplicableIndexers,
indexerAccess.Type));
}
// Shared helper for MakeObjectCreationWithInitializer and MakeNewT
private BoundExpression MakeObjectCreationWithInitializer(
CSharpSyntaxNode syntax,
BoundExpression rewrittenObjectCreation,
BoundExpression initializerExpression,
TypeSymbol type)
{
Debug.Assert(!inExpressionLambda);
Debug.Assert(initializerExpression != null && !initializerExpression.HasErrors);
// Create a temp and assign it with the object creation expression.
BoundAssignmentOperator boundAssignmentToTemp;
BoundLocal boundTemp = this.factory.StoreToTemp(rewrittenObjectCreation, out boundAssignmentToTemp);
// Rewrite object/collection initializer expressions
ArrayBuilder <BoundExpression> dynamicSiteInitializers = null;
ArrayBuilder <BoundExpression> loweredInitializers = ArrayBuilder <BoundExpression> .GetInstance();
AddObjectOrCollectionInitializers(ref dynamicSiteInitializers, loweredInitializers, boundTemp, initializerExpression);
int dynamicSiteCount = (dynamicSiteInitializers != null) ? dynamicSiteInitializers.Count : 0;
var sideEffects = new BoundExpression[1 + dynamicSiteCount + loweredInitializers.Count];
sideEffects[0] = boundAssignmentToTemp;
if (dynamicSiteCount > 0)
{
dynamicSiteInitializers.CopyTo(sideEffects, 1);
dynamicSiteInitializers.Free();
}
loweredInitializers.CopyTo(sideEffects, 1 + dynamicSiteCount);
loweredInitializers.Free();
return(new BoundSequence(
syntax: syntax,
locals: ImmutableArray.Create(boundTemp.LocalSymbol),
sideEffects: sideEffects.AsImmutableOrNull(),
value: boundTemp,
type: type));
}
internal static ImmutableArray <BoundExpression> GetCallSiteArguments(BoundExpression callSiteFieldAccess, BoundExpression receiver, ImmutableArray <BoundExpression> arguments, BoundExpression right)
{
var result = new BoundExpression[1 + (receiver != null ? 1 : 0) + arguments.Length + (right != null ? 1 : 0)];
int j = 0;
result[j++] = callSiteFieldAccess;
if (receiver != null)
{
result[j++] = receiver;
}
arguments.CopyTo(result, j);
j += arguments.Length;
if (right != null)
{
result[j++] = right;
}
return(result.AsImmutableOrNull());
}
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, argumentRefKinds, rewrittenArguments, 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);
// 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));
}
public BoundExpression Array(TypeSymbol elementType, BoundExpression[] elements)
{
return Array(elementType, elements.AsImmutableOrNull());
}
public BoundExpression Sequence(BoundExpression[] sideEffects, BoundExpression result, TypeSymbol type = null)
{
return new BoundSequence(Syntax, ImmutableArray<LocalSymbol>.Empty, sideEffects.AsImmutableOrNull(), result, type ?? result.Type) { WasCompilerGenerated = true };
}
internal static ImmutableArray<BoundExpression> GetCallSiteArguments(BoundExpression callSiteFieldAccess, BoundExpression receiver, ImmutableArray<BoundExpression> arguments, BoundExpression right)
{
var result = new BoundExpression[1 + (receiver != null ? 1 : 0) + arguments.Length + (right != null ? 1 : 0)];
int j = 0;
result[j++] = callSiteFieldAccess;
if (receiver != null)
{
result[j++] = receiver;
}
arguments.CopyTo(result, j);
j += arguments.Length;
if (right != null)
{
result[j++] = right;
}
return result.AsImmutableOrNull();
}
private BoundExpression MakeBinderConstruction(WellKnownMember factoryMethod, BoundExpression[] args)
{
var binderFactory = _factory.WellKnownMember(factoryMethod);
if ((object)binderFactory == null)
{
return null;
}
return _factory.Call(null, (MethodSymbol)binderFactory, args.AsImmutableOrNull());
}
/// <summary>
/// Process tempStores and add them as sideeffects to arguments where needed. The return
/// value tells how many temps are actually needed. For unnecessary temps the corresponding
/// temp store will be cleared.
/// </summary>
private static int MergeArgumentsAndSideEffects(
BoundExpression[] arguments,
ArrayBuilder <RefKind> refKinds,
ArrayBuilder <BoundAssignmentOperator> tempStores)
{
Debug.Assert(arguments != null);
Debug.Assert(refKinds != null);
Debug.Assert(tempStores != null);
int tempsRemainedInUse = tempStores.Count;
// Suppose we've got temporaries: t0 = A(), t1 = B(), t2 = C(), t4 = D(), t5 = E()
// and arguments: t0, t2, t1, t4, 10, t5
//
// We wish to produce arguments list: A(), SEQ(t1=B(), C()), t1, D(), 10, E()
//
// Our algorithm essentially finds temp stores that must happen before given argument
// load, and if there are any they become side effects of the given load.
// Stores immediately followed by loads of the same thing can be eliminated.
//
// Constraints:
// Stores must happen before corresponding loads.
// Stores cannot move relative to other stores. If arg was movable it would not need a temp.
int firstUnclaimedStore = 0;
for (int a = 0; a < arguments.Length; ++a)
{
var argument = arguments[a];
// if argument is a load, search for corresponding store. if store is found, extract
// the actual expression we were storing and add it as an argument - this one does
// not need a temp. if there are any unclaimed stores before the found one, add them
// as side effects that precede this arg, they cannot happen later.
if (argument.Kind == BoundKind.Local)
{
var correspondingStore = -1;
for (int i = firstUnclaimedStore; i < tempStores.Count; i++)
{
if (tempStores[i].Left == argument)
{
correspondingStore = i;
break;
}
}
// store found?
if (correspondingStore != -1)
{
var value = tempStores[correspondingStore].Right;
// When we created the temp, we dropped the argument RefKind
// since the local contained its own RefKind. Since we're removing
// the temp, the argument RefKind needs to be restored.
refKinds[a] = ((BoundLocal)argument).LocalSymbol.RefKind;
// the matched store will not need to go into sideffects, only ones before it will
// remove the store to signal that we are not using its temp.
tempStores[correspondingStore] = null;
tempsRemainedInUse--;
// no need for sideeffects?
// just combine store and load
if (correspondingStore == firstUnclaimedStore)
{
arguments[a] = value;
}
else
{
var sideffects = new BoundExpression[correspondingStore - firstUnclaimedStore];
for (int s = 0; s < sideffects.Length; s++)
{
sideffects[s] = tempStores[firstUnclaimedStore + s];
}
arguments[a] = new BoundSequence(
value.Syntax,
// this sequence does not own locals. Note that temps that
// we use for the rewrite are stored in one arg and loaded
// in another so they must live in a scope above.
ImmutableArray <LocalSymbol> .Empty,
sideffects.AsImmutableOrNull(),
value,
value.Type);
}
firstUnclaimedStore = correspondingStore + 1;
}
}
}
Debug.Assert(firstUnclaimedStore == tempStores.Count, "not all sideeffects were claimed");
return(tempsRemainedInUse);
}
private BoundExpression BindAnonymousObjectCreation(AnonymousObjectCreationExpressionSyntax node, DiagnosticBag diagnostics)
{
// prepare
var initializers = node.Initializers;
int fieldCount = initializers.Count;
bool hasError = false;
// bind field initializers
BoundExpression[] boundExpressions = new BoundExpression[fieldCount];
AnonymousTypeField[] fields = new AnonymousTypeField[fieldCount];
CSharpSyntaxNode[] fieldSyntaxNodes = new CSharpSyntaxNode[fieldCount];
// WARNING: Note that SemanticModel.GetDeclaredSymbol for field initializer node relies on
// the fact that the order of properties in anonymous type template corresponds
// 1-to-1 to the appropriate filed initializer syntax nodes; This means such
// correspondence must be preserved all the time including erroneos scenarios
// set of names already used
HashSet<string> uniqueFieldNames = new HashSet<string>();
for (int i = 0; i < fieldCount; i++)
{
AnonymousObjectMemberDeclaratorSyntax fieldInitializer = initializers[i];
NameEqualsSyntax nameEquals = fieldInitializer.NameEquals;
ExpressionSyntax expression = fieldInitializer.Expression;
SyntaxToken nameToken = default(SyntaxToken);
if (nameEquals != null)
{
nameToken = nameEquals.Name.Identifier;
}
else
{
nameToken = expression.ExtractAnonymousTypeMemberName();
}
hasError = hasError || expression.HasErrors;
boundExpressions[i] = this.BindValue(expression, diagnostics, BindValueKind.RValue);
// check the name to be unique
string fieldName = null;
if (nameToken.Kind() == SyntaxKind.IdentifierToken)
{
fieldName = nameToken.ValueText;
if (uniqueFieldNames.Contains(fieldName))
{
// name duplication
Error(diagnostics, ErrorCode.ERR_AnonymousTypeDuplicatePropertyName, fieldInitializer);
hasError = true;
fieldName = null;
}
else
{
uniqueFieldNames.Add(fieldName);
}
}
else
{
// there is something wrong with field's name
hasError = true;
}
// calculate the expression's type and report errors if needed
TypeSymbol fieldType = GetAnonymousTypeFieldType(boundExpressions[i], fieldInitializer, diagnostics, ref hasError);
// build anonymous type field descriptor
fieldSyntaxNodes[i] = (nameToken.Kind() == SyntaxKind.IdentifierToken) ? (CSharpSyntaxNode)nameToken.Parent : fieldInitializer;
fields[i] = new AnonymousTypeField(fieldName == null ? "$" + i.ToString() : fieldName, fieldSyntaxNodes[i].Location, fieldType);
// NOTE: ERR_InvalidAnonymousTypeMemberDeclarator (CS0746) would be generated by parser if needed
}
// Create anonymous type
AnonymousTypeManager manager = this.Compilation.AnonymousTypeManager;
AnonymousTypeDescriptor descriptor = new AnonymousTypeDescriptor(fields.AsImmutableOrNull(), node.NewKeyword.GetLocation());
NamedTypeSymbol anonymousType = manager.ConstructAnonymousTypeSymbol(descriptor);
// declarators - bound nodes created for providing semantic info
// on anonymous type fields having explicitly specified name
ArrayBuilder<BoundAnonymousPropertyDeclaration> declarators =
ArrayBuilder<BoundAnonymousPropertyDeclaration>.GetInstance();
for (int i = 0; i < fieldCount; i++)
{
NameEqualsSyntax explicitName = initializers[i].NameEquals;
if (explicitName != null)
{
AnonymousTypeField field = fields[i];
if (field.Name != null)
{
// get property symbol and create a bound property declaration node
foreach (var symbol in anonymousType.GetMembers(field.Name))
{
if (symbol.Kind == SymbolKind.Property)
{
declarators.Add(new BoundAnonymousPropertyDeclaration(fieldSyntaxNodes[i], (PropertySymbol)symbol, field.Type));
break;
}
}
}
}
}
// check if anonymous object creation is allowed in this context
if (!this.IsAnonymousTypesAllowed())
{
Error(diagnostics, ErrorCode.ERR_AnonymousTypeNotAvailable, node.NewKeyword);
hasError = true;
}
// Finally create a bound node
return new BoundAnonymousObjectCreationExpression(
node,
anonymousType.InstanceConstructors[0],
boundExpressions.AsImmutableOrNull(),
declarators.ToImmutableAndFree(),
anonymousType,
hasError);
}
public ImmutableArray<BoundExpression> TypeOfs(ImmutableArray<TypeSymbol> typeArguments)
{
var result = new BoundExpression[typeArguments.Length];
for (int i = 0; i < typeArguments.Length; i++)
{
result[i] = Typeof(typeArguments[i]);
}
return result.AsImmutableOrNull();
}
private BoundDynamicIndexerAccess TransformDynamicIndexerAccess(BoundDynamicIndexerAccess indexerAccess, ArrayBuilder<BoundExpression> stores, ArrayBuilder<LocalSymbol> temps)
{
BoundExpression loweredReceiver;
if (CanChangeValueBetweenReads(indexerAccess.ReceiverOpt))
{
BoundAssignmentOperator assignmentToTemp;
var temp = _factory.StoreToTemp(VisitExpression(indexerAccess.ReceiverOpt), out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredReceiver = temp;
}
else
{
loweredReceiver = indexerAccess.ReceiverOpt;
}
var arguments = indexerAccess.Arguments;
var loweredArguments = new BoundExpression[arguments.Length];
for (int i = 0; i < arguments.Length; i++)
{
if (CanChangeValueBetweenReads(arguments[i]))
{
BoundAssignmentOperator assignmentToTemp;
var temp = _factory.StoreToTemp(VisitExpression(arguments[i]), out assignmentToTemp, indexerAccess.ArgumentRefKindsOpt.RefKinds(i) != RefKind.None ? RefKind.Ref : RefKind.None);
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredArguments[i] = temp;
}
else
{
loweredArguments[i] = arguments[i];
}
}
return new BoundDynamicIndexerAccess(
indexerAccess.Syntax,
loweredReceiver,
loweredArguments.AsImmutableOrNull(),
indexerAccess.ArgumentNamesOpt,
indexerAccess.ArgumentRefKindsOpt,
indexerAccess.ApplicableIndexers,
indexerAccess.Type);
}
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, argumentRefKinds, rewrittenArguments, 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.)
var getMethod = indexer.GetOwnOrInheritedGetMethod();
Debug.Assert((object)getMethod != null);
InsertMissingOptionalArguments(syntax, getMethod.Parameters, actualArguments);
// 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();
// CONSIDER: this is a temporary object that will be rewritten away before this lowering completes.
// Mitigation: this will only produce short-lived garbage for compound assignments and increments/decrements of indexers.
return new BoundIndexerAccess(
syntax,
transformedReceiver,
indexer,
rewrittenArguments,
default(ImmutableArray<string>),
argumentRefKinds,
false,
default(ImmutableArray<int>),
indexerAccess.Type);
}
/// <summary>
/// In the expanded form of a compound assignment (or increment/decrement), the LHS appears multiple times.
/// If we aren't careful, this can result in repeated side-effects. This creates (ordered) temps for all of the
/// subexpressions that could result in side-effects and returns a side-effect-free expression that can be used
/// in place of the LHS in the expanded form.
/// </summary>
/// <param name="originalLHS">The LHS sub-expression of the compound assignment (or increment/decrement).</param>
/// <param name="stores">Populated with a list of assignment expressions that initialize the temporary locals.</param>
/// <param name="temps">Populated with a list of temporary local symbols.</param>
/// <param name="isDynamicAssignment">True if the compound assignment is a dynamic operation.</param>
/// <returns>
/// A side-effect-free expression representing the LHS.
/// The returned node needs to be lowered but its children are already lowered.
/// </returns>
private BoundExpression TransformCompoundAssignmentLHS(BoundExpression originalLHS, ArrayBuilder <BoundExpression> stores, ArrayBuilder <LocalSymbol> temps, bool isDynamicAssignment)
{
// There are five possible cases.
//
// Case 1: receiver.Prop += value is transformed into
// temp = receiver
// temp.Prop = temp.Prop + value
// and a later rewriting will turn that into calls to getters and setters.
//
// Case 2: collection[i1, i2, i3] += value is transformed into
// tc = collection
// t1 = i1
// t2 = i2
// t3 = i3
// tc[t1, t2, t3] = tc[t1, t2, t3] + value
// and again, a later rewriting will turn that into getters and setters of the indexer.
//
// Case 3: local += value (and param += value) needs no temporaries; it simply
// becomes local = local + value.
//
// Case 4: staticField += value needs no temporaries either. However, classInst.field += value becomes
// temp = classInst
// temp.field = temp.field + value
//
// Case 5: otherwise, it must be structVariable.field += value or array[index] += value. Either way
// we have a variable on the left. Transform it into:
// ref temp = ref variable
// temp = temp + value
switch (originalLHS.Kind)
{
case BoundKind.PropertyAccess:
{
// We need to stash away the receiver so that it does not get evaluated twice.
// If the receiver is classified as a value of reference type then we can simply say
//
// R temp = receiver
// temp.prop = temp.prop + rhs
//
// But if the receiver is classified as a variable of struct type then we
// cannot make a copy of the value; we need to make sure that we mutate
// the original receiver, not the copy. We have to generate
//
// ref R temp = ref receiver
// temp.prop = temp.prop + rhs
//
// The rules of C# (in section 7.17.1) require that if you have receiver.prop
// as the target of an assignment such that receiver is a value type, it must
// be classified as a variable. If we've gotten this far in the rewriting,
// assume that was the case.
var prop = (BoundPropertyAccess)originalLHS;
// If the property is static or if the receiver is of kind "Base" or "this", then we can just generate prop = prop + value
if (prop.ReceiverOpt == null || prop.PropertySymbol.IsStatic || !IntroducingReadCanBeObservable(prop.ReceiverOpt))
{
return(prop);
}
Debug.Assert(prop.ReceiverOpt.Kind != BoundKind.TypeExpression);
BoundExpression rewrittenReceiver = VisitExpression(prop.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);
stores.Add(assignmentToTemp);
temps.Add(receiverTemp.LocalSymbol);
// CONSIDER: this is a temporary object that will be rewritten away before this lowering completes.
// Mitigation: this will only produce short-lived garbage for compound assignments and increments/decrements of properties.
return(new BoundPropertyAccess(prop.Syntax, receiverTemp, prop.PropertySymbol, prop.ResultKind, prop.Type));
}
case BoundKind.DynamicMemberAccess:
{
var memberAccess = (BoundDynamicMemberAccess)originalLHS;
if (!IntroducingReadCanBeObservable(memberAccess.Receiver))
{
return(memberAccess);
}
// store receiver to temp:
var rewrittenReceiver = VisitExpression(memberAccess.Receiver);
BoundAssignmentOperator assignmentToTemp;
var receiverTemp = _factory.StoreToTemp(rewrittenReceiver, out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(receiverTemp.LocalSymbol);
return(new BoundDynamicMemberAccess(memberAccess.Syntax, receiverTemp, memberAccess.TypeArgumentsOpt, memberAccess.Name, memberAccess.Invoked, memberAccess.Indexed, memberAccess.Type));
}
case BoundKind.IndexerAccess:
{
BoundIndexerAccess indexerAccess = (BoundIndexerAccess)originalLHS;
var receiverOpt = indexerAccess.ReceiverOpt;
Debug.Assert(receiverOpt != null);
BoundExpression transformedReceiver;
if (IntroducingReadCanBeObservable(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);
CSharpSyntaxNode 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, argumentRefKinds, rewrittenArguments, 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.)
var getMethod = indexer.GetOwnOrInheritedGetMethod();
Debug.Assert((object)getMethod != null);
InsertMissingOptionalArguments(syntax, getMethod.Parameters, actualArguments);
// 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();
// CONSIDER: this is a temporary object that will be rewritten away before this lowering completes.
// Mitigation: this will only produce short-lived garbage for compound assignments and increments/decrements of indexers.
return(new BoundIndexerAccess(
syntax,
transformedReceiver,
indexer,
rewrittenArguments,
default(ImmutableArray <string>),
argumentRefKinds,
false,
default(ImmutableArray <int>),
indexerAccess.Type));
}
case BoundKind.Local:
case BoundKind.Parameter:
case BoundKind.ThisReference: // a special kind of parameter
// No temporaries are needed. Just generate local = local + value
return(originalLHS);
case BoundKind.FieldAccess:
{
// * If the field is static then no temporaries are needed.
// * If the field is not static and the receiver is of reference type then generate t = r; t.f = t.f + value
// * If the field is not static and the receiver is a variable of value type then we'll fall into the
// general variable case below.
var fieldAccess = (BoundFieldAccess)originalLHS;
BoundExpression receiverOpt = fieldAccess.ReceiverOpt;
//If the receiver is static or is the receiver is of kind "Base" or "this", then we can just generate field = field + value
if (fieldAccess.FieldSymbol.IsStatic || !IntroducingReadCanBeObservable(receiverOpt))
{
return(fieldAccess);
}
if (receiverOpt.Type.IsReferenceType)
{
Debug.Assert(receiverOpt.Kind != BoundKind.TypeExpression);
BoundExpression rewrittenReceiver = VisitExpression(receiverOpt);
if (rewrittenReceiver.Type.IsTypeParameter())
{
var memberContainingType = fieldAccess.FieldSymbol.ContainingType;
// From the verifier prospective type parameters do not contain fields or methods.
// the instance must be "boxed" to access the field
// It makes sense to box receiver before storing into a temp - no need to box twice.
rewrittenReceiver = BoxReceiver(rewrittenReceiver, memberContainingType);
}
BoundAssignmentOperator assignmentToTemp;
var receiverTemp = _factory.StoreToTemp(rewrittenReceiver, out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(receiverTemp.LocalSymbol);
return(new BoundFieldAccess(fieldAccess.Syntax, receiverTemp, fieldAccess.FieldSymbol, null));
}
break;
}
case BoundKind.DynamicIndexerAccess:
{
var indexerAccess = (BoundDynamicIndexerAccess)originalLHS;
BoundExpression loweredReceiver;
if (IntroducingReadCanBeObservable(indexerAccess.ReceiverOpt))
{
BoundAssignmentOperator assignmentToTemp;
var temp = _factory.StoreToTemp(VisitExpression(indexerAccess.ReceiverOpt), out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredReceiver = temp;
}
else
{
loweredReceiver = indexerAccess.ReceiverOpt;
}
var arguments = indexerAccess.Arguments;
var loweredArguments = new BoundExpression[arguments.Length];
for (int i = 0; i < arguments.Length; i++)
{
if (IntroducingReadCanBeObservable(arguments[i]))
{
BoundAssignmentOperator assignmentToTemp;
var temp = _factory.StoreToTemp(VisitExpression(arguments[i]), out assignmentToTemp, refKind: indexerAccess.ArgumentRefKindsOpt.RefKinds(i));
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredArguments[i] = temp;
}
else
{
loweredArguments[i] = arguments[i];
}
}
return(new BoundDynamicIndexerAccess(
indexerAccess.Syntax,
loweredReceiver,
loweredArguments.AsImmutableOrNull(),
indexerAccess.ArgumentNamesOpt,
indexerAccess.ArgumentRefKindsOpt,
indexerAccess.ApplicableIndexers,
indexerAccess.Type));
}
case BoundKind.ArrayAccess:
if (isDynamicAssignment)
{
// In non-dynamic array[index] op= R we emit:
// T& tmp = &array[index];
// *tmp = *L op R;
// where T is the type of L.
//
// If L is an array access, the assignment is dynamic, the compile-time of the array is dynamic[]
// and the runtime type of the array is not object[] (but e.g. string[]) the pointer approach is broken.
// T is Object in such case and we can't take a read-write pointer of type Object& to an array element of non-object type.
//
// In this case we rewrite the assignment as follows:
//
// E t_array = array;
// I t_index = index; (possibly more indices)
// T value = t_array[t_index];
// t_array[t_index] = value op R;
var arrayAccess = (BoundArrayAccess)originalLHS;
var loweredArray = VisitExpression(arrayAccess.Expression);
var loweredIndices = VisitList(arrayAccess.Indices);
return(SpillArrayElementAccess(loweredArray, loweredIndices, stores, temps));
}
break;
case BoundKind.PointerElementAccess:
case BoundKind.PointerIndirectionOperator:
case BoundKind.RefValueOperator:
break;
default:
throw ExceptionUtilities.UnexpectedValue(originalLHS.Kind);
}
// We made no transformation above. Either we have array[index] += value or
// structVariable.field += value; either way we have a potentially complicated variable-
// producing expression on the left. Generate
// ref temp = ref variable; temp = temp + value
// Rewrite the variable. Here we depend on the fact that the only forms
// rewritten here are rewritten the same for lvalues and rvalues.
BoundExpression rewrittenVariable = VisitExpression(originalLHS);
BoundAssignmentOperator assignmentToTemp2;
var variableTemp = _factory.StoreToTemp(rewrittenVariable, out assignmentToTemp2, refKind: RefKind.Ref);
stores.Add(assignmentToTemp2);
temps.Add(variableTemp.LocalSymbol);
return(variableTemp);
}
// Shared helper for MakeObjectCreationWithInitializer and MakeNewT
private BoundExpression MakeObjectCreationWithInitializer(
CSharpSyntaxNode syntax,
BoundExpression rewrittenObjectCreation,
BoundExpression initializerExpression,
TypeSymbol type)
{
Debug.Assert(!inExpressionLambda);
Debug.Assert(initializerExpression != null && !initializerExpression.HasErrors);
// Create a temp and assign it with the object creation expression.
BoundAssignmentOperator boundAssignmentToTemp;
BoundLocal boundTemp = this.factory.StoreToTemp(rewrittenObjectCreation, out boundAssignmentToTemp);
// Rewrite object/collection initializer expressions
ArrayBuilder<BoundExpression> dynamicSiteInitializers = null;
ArrayBuilder<BoundExpression> loweredInitializers = ArrayBuilder<BoundExpression>.GetInstance();
AddObjectOrCollectionInitializers(ref dynamicSiteInitializers, loweredInitializers, boundTemp, initializerExpression);
int dynamicSiteCount = (dynamicSiteInitializers != null) ? dynamicSiteInitializers.Count : 0;
var sideEffects = new BoundExpression[1 + dynamicSiteCount + loweredInitializers.Count];
sideEffects[0] = boundAssignmentToTemp;
if (dynamicSiteCount > 0)
{
dynamicSiteInitializers.CopyTo(sideEffects, 1);
dynamicSiteInitializers.Free();
}
loweredInitializers.CopyTo(sideEffects, 1 + dynamicSiteCount);
loweredInitializers.Free();
return new BoundSequence(
syntax: syntax,
locals: ImmutableArray.Create(boundTemp.LocalSymbol),
sideEffects: sideEffects.AsImmutableOrNull(),
value: boundTemp,
type: type);
}
/// <summary>
/// Rewrites arguments of an invocation according to the receiving method or indexer.
/// It is assumed that each argument has already been lowered, but we may need
/// additional rewriting for the arguments, such as generating a params array, re-ordering
/// arguments based on <paramref name="argsToParamsOpt"/> map, inserting arguments for optional parameters, etc.
/// <paramref name="optionalParametersMethod"/> is the method used for values of any optional parameters.
/// For indexers, this method must be an accessor, and for methods it must be the method
/// itself. <paramref name="optionalParametersMethod"/> is needed for indexers since getter and setter
/// may have distinct optional parameter values.
/// </summary>
private ImmutableArray<BoundExpression> MakeArguments(
SyntaxNode syntax,
ImmutableArray<BoundExpression> rewrittenArguments,
Symbol methodOrIndexer,
MethodSymbol optionalParametersMethod,
bool expanded,
ImmutableArray<int> argsToParamsOpt,
ref ImmutableArray<RefKind> argumentRefKindsOpt,
out ImmutableArray<LocalSymbol> temps,
bool invokedAsExtensionMethod = false,
ThreeState enableCallerInfo = ThreeState.Unknown)
{
// Either the methodOrIndexer is a property, in which case the method used
// for optional parameters is an accessor of that property (or an overridden
// property), or the methodOrIndexer is used for optional parameters directly.
Debug.Assert(((methodOrIndexer.Kind == SymbolKind.Property) && optionalParametersMethod.IsAccessor()) ||
ReferenceEquals(methodOrIndexer, optionalParametersMethod));
// We need to do a fancy rewrite under the following circumstances:
// (1) a params array is being used; we need to generate the array.
// (2) there were named arguments that reordered the arguments; we might
// have to generate temporaries to ensure that the arguments are
// evaluated in source code order, not the actual call order.
// (3) there were optional parameters that had no corresponding arguments.
//
// If none of those are the case then we can just take an early out.
// An applicable "vararg" method could not possibly be applicable in its expanded
// form, and cannot possibly have named arguments or used optional parameters,
// because the __arglist() argument has to be positional and in the last position.
if (methodOrIndexer.GetIsVararg())
{
Debug.Assert(rewrittenArguments.Length == methodOrIndexer.GetParameterCount() + 1);
Debug.Assert(argsToParamsOpt.IsDefault);
Debug.Assert(!expanded);
temps = default(ImmutableArray<LocalSymbol>);
return rewrittenArguments;
}
var receiverNamedType = invokedAsExtensionMethod ?
((MethodSymbol)methodOrIndexer).Parameters[0].Type as NamedTypeSymbol :
methodOrIndexer.ContainingType;
bool isComReceiver = (object)receiverNamedType != null && receiverNamedType.IsComImport;
if (rewrittenArguments.Length == methodOrIndexer.GetParameterCount() &&
argsToParamsOpt.IsDefault &&
!expanded &&
!isComReceiver)
{
temps = default(ImmutableArray<LocalSymbol>);
return rewrittenArguments;
}
// We have:
// * a list of arguments, already converted to their proper types,
// in source code order. Some optional arguments might be missing.
// * a map showing which parameter each argument corresponds to. If
// this is null, then the argument to parameter mapping is one-to-one.
// * the ref kind of each argument, in source code order. That is, whether
// the argument was marked as ref, out, or value (neither).
// * a method symbol.
// * whether the call is expanded or normal form.
// We rewrite the call so that:
// * if in its expanded form, we create the params array.
// * if the call requires reordering of arguments because of named arguments, temporaries are generated as needed
// Doing this transformation can move around refness in interesting ways. For example, consider
//
// A().M(y : ref B()[C()], x : out D());
//
// This will be created as a call with receiver A(), symbol M, argument list ( B()[C()], D() ),
// name list ( y, x ) and ref list ( ref, out ). We can rewrite this into temporaries:
//
// A().M(
// seq ( ref int temp_y = ref B()[C()], out D() ),
// temp_y );
//
// Now we have a call with receiver A(), symbol M, argument list as shown, no name list,
// and ref list ( out, value ). We do not want to pass a *ref* to temp_y; the temporary
// storage is not the thing being ref'd! We want to pass the *value* of temp_y, which
// *contains* a reference.
// We attempt to minimize the number of temporaries required. Arguments which neither
// produce nor observe a side effect can be placed into their proper position without
// recourse to a temporary. For example:
//
// Where(predicate: x=>x.Length!=0, sequence: S())
//
// can be rewritten without any temporaries because the conversion from lambda to
// delegate does not produce any side effect that could be observed by S().
//
// By contrast:
//
// Foo(z: this.p, y: this.Q(), x: (object)10)
//
// The boxing of 10 can be reordered, but the fetch of this.p has to happen before the
// call to this.Q() because the call could change the value of this.p.
//
// We start by binding everything that is not obviously reorderable as a temporary, and
// then run an optimizer to remove unnecessary temporaries.
ImmutableArray<ParameterSymbol> parameters = methodOrIndexer.GetParameters();
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, argumentRefKindsOpt, rewrittenArguments, actualArguments, refKinds, storesToTemps);
// all the formal arguments, except missing optionals, are now in place.
// Optimize away unnecessary temporaries.
// Necessary temporaries have their store instructions merged into the appropriate
// argument expression.
ArrayBuilder<LocalSymbol> temporariesBuilder = ArrayBuilder<LocalSymbol>.GetInstance();
OptimizeTemporaries(actualArguments, refKinds, storesToTemps, temporariesBuilder);
// Step two: If we have a params array, build the array and fill in the argument.
if (expanded)
{
actualArguments[actualArguments.Length - 1] = BuildParamsArray(syntax, methodOrIndexer, argsToParamsOpt, rewrittenArguments, parameters, actualArguments[actualArguments.Length - 1]);
}
// Step three: Now fill in the optional arguments.
InsertMissingOptionalArguments(syntax, optionalParametersMethod.Parameters, actualArguments, enableCallerInfo);
if (isComReceiver)
{
RewriteArgumentsForComCall(parameters, actualArguments, refKinds, temporariesBuilder);
}
temps = temporariesBuilder.ToImmutableAndFree();
storesToTemps.Free();
// * The refkind map is now filled out to match the arguments.
// * The list of parameter names is now null because the arguments have been reordered.
// * The args-to-params map is now null because every argument exactly matches its parameter.
// * The call is no longer in its expanded form.
argumentRefKindsOpt = GetRefKindsOrNull(refKinds);
refKinds.Free();
return actualArguments.AsImmutableOrNull();
}
/// <summary>
/// In the expanded form of a compound assignment (or increment/decrement), the LHS appears multiple times.
/// If we aren't careful, this can result in repeated side-effects. This creates (ordered) temps for all of the
/// subexpressions that could result in side-effects and returns a side-effect-free expression that can be used
/// in place of the LHS in the expanded form.
/// </summary>
/// <param name="originalLHS">The LHS sub-expression of the compound assignment (or increment/decrement).</param>
/// <param name="stores">Populated with a list of assignment expressions that initialize the temporary locals.</param>
/// <param name="temps">Populated with a list of temporary local symbols.</param>
/// <param name="isDynamicAssignment">True if the compound assignment is a dynamic operation.</param>
/// <returns>
/// A side-effect-free expression representing the LHS.
/// The returned node needs to be lowered but its children are already lowered.
/// </returns>
private BoundExpression TransformCompoundAssignmentLHS(BoundExpression originalLHS, ArrayBuilder<BoundExpression> stores, ArrayBuilder<LocalSymbol> temps, bool isDynamicAssignment)
{
// There are five possible cases.
//
// Case 1: receiver.Prop += value is transformed into
// temp = receiver
// temp.Prop = temp.Prop + value
// and a later rewriting will turn that into calls to getters and setters.
//
// Case 2: collection[i1, i2, i3] += value is transformed into
// tc = collection
// t1 = i1
// t2 = i2
// t3 = i3
// tc[t1, t2, t3] = tc[t1, t2, t3] + value
// and again, a later rewriting will turn that into getters and setters of the indexer.
//
// Case 3: local += value (and param += value) needs no temporaries; it simply
// becomes local = local + value.
//
// Case 4: staticField += value needs no temporaries either. However, classInst.field += value becomes
// temp = classInst
// temp.field = temp.field + value
//
// Case 5: otherwise, it must be structVariable.field += value or array[index] += value. Either way
// we have a variable on the left. Transform it into:
// ref temp = ref variable
// temp = temp + value
switch (originalLHS.Kind)
{
case BoundKind.PropertyAccess:
{
// We need to stash away the receiver so that it does not get evaluated twice.
// If the receiver is classified as a value of reference type then we can simply say
//
// R temp = receiver
// temp.prop = temp.prop + rhs
//
// But if the receiver is classified as a variable of struct type then we
// cannot make a copy of the value; we need to make sure that we mutate
// the original receiver, not the copy. We have to generate
//
// ref R temp = ref receiver
// temp.prop = temp.prop + rhs
//
// The rules of C# (in section 7.17.1) require that if you have receiver.prop
// as the target of an assignment such that receiver is a value type, it must
// be classified as a variable. If we've gotten this far in the rewriting,
// assume that was the case.
var prop = (BoundPropertyAccess)originalLHS;
// If the property is static or is the receiver is of kind "Base" or "this", then we can just generate prop = prop + value
if (prop.ReceiverOpt == null || prop.PropertySymbol.IsStatic || !NeedsTemp(prop.ReceiverOpt))
{
return prop;
}
Debug.Assert(prop.ReceiverOpt.Kind != BoundKind.TypeExpression);
// Can we ever avoid storing the receiver in a temp? If the receiver is a variable then it
// might be modified by the computation of the getter, the value, or the operation.
// The receiver cannot be a null constant or constant of value type. It could be a
// constant of string type, but there are no mutable properties of a string.
// Similarly, there are no mutable properties of a Type object, so the receiver
// cannot be a typeof(T) expression. The only situation we know of is where we could
// optimize away the temp is if the receiver is a readonly field of reference type,
// we are not in a constructor, and the receiver of the *field*, if any, is also idempotent.
// It doesn't seem worthwhile to pursue an optimization for this exceedingly rare case.
BoundExpression rewrittenReceiver = VisitExpression(prop.ReceiverOpt);
if (rewrittenReceiver.Type.IsTypeParameter() && rewrittenReceiver.Type.IsReferenceType)
{
var memberContainingType = prop.PropertySymbol.ContainingType;
// From the verifier prospective type parameters do not contain fields or methods.
// the instance must be boxed/constrained to access the member even if known to be a reference
// It makes sense to box reference receiver before storing into a temp - no need to box/constrain twice.
rewrittenReceiver = BoxReceiver(rewrittenReceiver, memberContainingType);
}
BoundAssignmentOperator assignmentToTemp;
var receiverTemp = this.factory.StoreToTemp(rewrittenReceiver, out assignmentToTemp, refKind: rewrittenReceiver.Type.IsReferenceType ? RefKind.None : RefKind.Ref);
stores.Add(assignmentToTemp);
temps.Add(receiverTemp.LocalSymbol);
// CONSIDER: this is a temporary object that will be rewritten away before this lowering completes.
// Mitigation: this will only produce short-lived garbage for compound assignments and increments/decrements of properties.
return new BoundPropertyAccess(prop.Syntax, receiverTemp, prop.PropertySymbol, prop.ResultKind, prop.Type);
}
case BoundKind.DynamicMemberAccess:
{
var memberAccess = (BoundDynamicMemberAccess)originalLHS;
if (!NeedsTemp(memberAccess.Receiver))
{
return memberAccess;
}
// store receiver to temp:
var rewrittenReceiver = VisitExpression(memberAccess.Receiver);
BoundAssignmentOperator assignmentToTemp;
var receiverTemp = this.factory.StoreToTemp(rewrittenReceiver, out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(receiverTemp.LocalSymbol);
return new BoundDynamicMemberAccess(memberAccess.Syntax, receiverTemp, memberAccess.TypeArgumentsOpt, memberAccess.Name, memberAccess.Invoked, memberAccess.Indexed, memberAccess.Type);
}
case BoundKind.IndexerAccess:
{
BoundIndexerAccess indexerAccess = (BoundIndexerAccess)originalLHS;
var receiverOpt = indexerAccess.ReceiverOpt;
Debug.Assert(receiverOpt != null);
BoundExpression transformedReceiver;
if (NeedsTemp(receiverOpt))
{
BoundExpression rewrittenReceiver = VisitExpression(receiverOpt);
if (rewrittenReceiver.Type.IsTypeParameter() && rewrittenReceiver.Type.IsReferenceType)
{
var memberContainingType = indexerAccess.Indexer.ContainingType;
// From the verifier prospective type parameters do not contain fields or methods.
// the instance must be boxed/constrained to access the member even if known to be a reference
// It makes sense to box reference receiver before storing into a temp - no need to box/constrain twice.
rewrittenReceiver = BoxReceiver(rewrittenReceiver, memberContainingType);
}
BoundAssignmentOperator assignmentToTemp;
var receiverTemp = this.factory.StoreToTemp(rewrittenReceiver, out assignmentToTemp, refKind: rewrittenReceiver.Type.IsReferenceType ? RefKind.None : RefKind.Ref);
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);
CSharpSyntaxNode 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, argumentRefKinds, rewrittenArguments, 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 = this.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.)
var getMethod = indexer.GetOwnOrInheritedGetMethod();
Debug.Assert((object)getMethod != null);
InsertMissingOptionalArguments(syntax, getMethod.Parameters, actualArguments);
// 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();
// CONSIDER: this is a temporary object that will be rewritten away before this lowering completes.
// Mitigation: this will only produce short-lived garbage for compound assignments and increments/decrements of indexers.
return new BoundIndexerAccess(
syntax,
transformedReceiver,
indexer,
rewrittenArguments,
default(ImmutableArray<string>),
argumentRefKinds,
false,
default(ImmutableArray<int>),
indexerAccess.Type);
}
case BoundKind.Local:
case BoundKind.Parameter:
case BoundKind.ThisReference: // a special kind of parameter
// No temporaries are needed. Just generate local = local + value
return originalLHS;
case BoundKind.DeclarationExpression:
var rewrittenDeclExpr = (BoundExpression)VisitDeclarationExpression((BoundDeclarationExpression)originalLHS);
switch (rewrittenDeclExpr.Kind)
{
case BoundKind.Local:
return rewrittenDeclExpr;
case BoundKind.Sequence:
var sequence = (BoundSequence)rewrittenDeclExpr;
stores.AddRange(sequence.SideEffects);
temps.AddRange(sequence.Locals);
if (sequence.Value.Kind == BoundKind.Local)
{
return sequence.Value;
}
break;
}
throw ExceptionUtilities.Unreachable;
case BoundKind.FieldAccess:
{
// * If the field is static then no temporaries are needed.
// * If the field is not static and the receiver is of reference type then generate t = r; t.f = t.f + value
// * If the field is not static and the receiver is a variable of value type then we'll fall into the
// general variable case below.
var fieldAccess = (BoundFieldAccess)originalLHS;
BoundExpression receiverOpt = fieldAccess.ReceiverOpt;
//If the receiver is static or is the receiver is of kind "Base" or "this", then we can just generate field = field + value
if (receiverOpt == null || fieldAccess.FieldSymbol.IsStatic || !NeedsTemp(receiverOpt))
{
return fieldAccess;
}
if (receiverOpt.Type.IsReferenceType)
{
Debug.Assert(receiverOpt.Kind != BoundKind.TypeExpression);
BoundExpression rewrittenReceiver = VisitExpression(receiverOpt);
if (rewrittenReceiver.Type.IsTypeParameter())
{
var memberContainingType = fieldAccess.FieldSymbol.ContainingType;
// From the verifier prospective type parameters do not contain fields or methods.
// the instance must be "boxed" to access the field
// It makes sense to box receiver before storing into a temp - no need to box twice.
rewrittenReceiver = BoxReceiver(rewrittenReceiver, memberContainingType);
}
BoundAssignmentOperator assignmentToTemp;
var receiverTemp = this.factory.StoreToTemp(rewrittenReceiver, out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(receiverTemp.LocalSymbol);
return new BoundFieldAccess(fieldAccess.Syntax, receiverTemp, fieldAccess.FieldSymbol, null);
}
break;
}
case BoundKind.DynamicIndexerAccess:
{
var indexerAccess = (BoundDynamicIndexerAccess)originalLHS;
BoundExpression loweredReceiver;
if (NeedsTemp(indexerAccess.ReceiverOpt))
{
BoundAssignmentOperator assignmentToTemp;
var temp = this.factory.StoreToTemp(VisitExpression(indexerAccess.ReceiverOpt), out assignmentToTemp);
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredReceiver = temp;
}
else
{
loweredReceiver = indexerAccess.ReceiverOpt;
}
var arguments = indexerAccess.Arguments;
var loweredArguments = new BoundExpression[arguments.Length];
for (int i = 0; i < arguments.Length; i++)
{
if (NeedsTemp(arguments[i]))
{
BoundAssignmentOperator assignmentToTemp;
var temp = this.factory.StoreToTemp(VisitExpression(arguments[i]), out assignmentToTemp, refKind: indexerAccess.ArgumentRefKindsOpt.RefKinds(i));
stores.Add(assignmentToTemp);
temps.Add(temp.LocalSymbol);
loweredArguments[i] = temp;
}
else
{
loweredArguments[i] = arguments[i];
}
}
return new BoundDynamicIndexerAccess(
indexerAccess.Syntax,
loweredReceiver,
loweredArguments.AsImmutableOrNull(),
indexerAccess.ArgumentNamesOpt,
indexerAccess.ArgumentRefKindsOpt,
indexerAccess.ApplicableIndexers,
indexerAccess.Type);
}
case BoundKind.ArrayAccess:
if (isDynamicAssignment)
{
// In non-dynamic array[index] op= R we emit:
// T& tmp = &array[index];
// *tmp = *L op R;
// where T is the type of L.
//
// If L is an array access, the assignment is dynamic, the compile-time of the array is dynamic[]
// and the runtime type of the array is not object[] (but e.g. string[]) the pointer approach is broken.
// T is Object in such case and we can't take a read-write pointer of type Object& to an array element of non-object type.
//
// In this case we rewrite the assignment as follows:
//
// E t_array = array;
// I t_index = index; (possibly more indices)
// T value = t_array[t_index];
// t_array[t_index] = value op R;
var arrayAccess = (BoundArrayAccess)originalLHS;
var loweredArray = VisitExpression(arrayAccess.Expression);
var loweredIndices = VisitList(arrayAccess.Indices);
return SpillArrayElementAccess(loweredArray, loweredIndices, stores, temps);
}
break;
case BoundKind.PointerElementAccess:
case BoundKind.PointerIndirectionOperator:
case BoundKind.RefValueOperator:
break;
default:
throw ExceptionUtilities.UnexpectedValue(originalLHS.Kind);
}
// We made no transformation above. Either we have array[index] += value or
// structVariable.field += value; either way we have a potentially complicated variable-
// producing expression on the left. Generate
// ref temp = ref variable; temp = temp + value
// Rewrite the variable. Here we depend on the fact that the only forms
// rewritten here are rewritten the same for lvalues and rvalues.
BoundExpression rewrittenVariable = VisitExpression(originalLHS);
BoundAssignmentOperator assignmentToTemp2;
var variableTemp = this.factory.StoreToTemp(rewrittenVariable, out assignmentToTemp2, refKind: RefKind.Ref);
stores.Add(assignmentToTemp2);
temps.Add(variableTemp.LocalSymbol);
return variableTemp;
}
/// <summary>
/// Process tempStores and add them as side-effects to arguments where needed. The return
/// value tells how many temps are actually needed. For unnecessary temps the corresponding
/// temp store will be cleared.
/// </summary>
private static int MergeArgumentsAndSideEffects(
BoundExpression[] arguments,
ArrayBuilder<RefKind> refKinds,
ArrayBuilder<BoundAssignmentOperator> tempStores)
{
Debug.Assert(arguments != null);
Debug.Assert(refKinds != null);
Debug.Assert(tempStores != null);
int tempsRemainedInUse = tempStores.Count;
// Suppose we've got temporaries: t0 = A(), t1 = B(), t2 = C(), t4 = D(), t5 = E()
// and arguments: t0, t2, t1, t4, 10, t5
//
// We wish to produce arguments list: A(), SEQ(t1=B(), C()), t1, D(), 10, E()
//
// Our algorithm essentially finds temp stores that must happen before given argument
// load, and if there are any they become side effects of the given load.
// Stores immediately followed by loads of the same thing can be eliminated.
//
// Constraints:
// Stores must happen before corresponding loads.
// Stores cannot move relative to other stores. If arg was movable it would not need a temp.
int firstUnclaimedStore = 0;
for (int a = 0; a < arguments.Length; ++a)
{
var argument = arguments[a];
// if argument is a load, search for corresponding store. if store is found, extract
// the actual expression we were storing and add it as an argument - this one does
// not need a temp. if there are any unclaimed stores before the found one, add them
// as side effects that precede this arg, they cannot happen later.
// NOTE: missing optional parameters are not filled yet and therefore nulls - no need to do anything for them
if (argument?.Kind == BoundKind.Local)
{
var correspondingStore = -1;
for (int i = firstUnclaimedStore; i < tempStores.Count; i++)
{
if (tempStores[i].Left == argument)
{
correspondingStore = i;
break;
}
}
// store found?
if (correspondingStore != -1)
{
var value = tempStores[correspondingStore].Right;
// When we created the temp, we dropped the argument RefKind
// since the local contained its own RefKind. Since we're removing
// the temp, the argument RefKind needs to be restored.
refKinds[a] = ((BoundLocal)argument).LocalSymbol.RefKind;
// the matched store will not need to go into side-effects, only ones before it will
// remove the store to signal that we are not using its temp.
tempStores[correspondingStore] = null;
tempsRemainedInUse--;
// no need for side-effects?
// just combine store and load
if (correspondingStore == firstUnclaimedStore)
{
arguments[a] = value;
}
else
{
var sideeffects = new BoundExpression[correspondingStore - firstUnclaimedStore];
for (int s = 0; s < sideeffects.Length; s++)
{
sideeffects[s] = tempStores[firstUnclaimedStore + s];
}
arguments[a] = new BoundSequence(
value.Syntax,
// this sequence does not own locals. Note that temps that
// we use for the rewrite are stored in one arg and loaded
// in another so they must live in a scope above.
ImmutableArray<LocalSymbol>.Empty,
sideeffects.AsImmutableOrNull(),
value,
value.Type);
}
firstUnclaimedStore = correspondingStore + 1;
}
}
}
Debug.Assert(firstUnclaimedStore == tempStores.Count, "not all side-effects were claimed");
return tempsRemainedInUse;
}
private BoundExpression BindAnonymousObjectCreation(AnonymousObjectCreationExpressionSyntax node, DiagnosticBag diagnostics)
{
// prepare
var initializers = node.Initializers;
int fieldCount = initializers.Count;
bool hasError = false;
// bind field initializers
BoundExpression[] boundExpressions = new BoundExpression[fieldCount];
AnonymousTypeField[] fields = new AnonymousTypeField[fieldCount];
CSharpSyntaxNode[] fieldSyntaxNodes = new CSharpSyntaxNode[fieldCount];
// WARNING: Note that SemanticModel.GetDeclaredSymbol for field initializer node relies on
// the fact that the order of properties in anonymous type template corresponds
// 1-to-1 to the appropriate filed initializer syntax nodes; This means such
// correspondence must be preserved all the time including erroneos scenarios
// set of names already used
HashSet <string> uniqueFieldNames = new HashSet <string>();
for (int i = 0; i < fieldCount; i++)
{
AnonymousObjectMemberDeclaratorSyntax fieldInitializer = initializers[i];
NameEqualsSyntax nameEquals = fieldInitializer.NameEquals;
ExpressionSyntax expression = fieldInitializer.Expression;
SyntaxToken nameToken = default(SyntaxToken);
if (nameEquals != null)
{
nameToken = nameEquals.Name.Identifier;
}
else
{
nameToken = expression.ExtractAnonymousTypeMemberName();
}
hasError = hasError || expression.HasErrors;
boundExpressions[i] = this.BindValue(expression, diagnostics, BindValueKind.RValue);
// check the name to be unique
string fieldName = null;
if (nameToken.CSharpKind() == SyntaxKind.IdentifierToken)
{
fieldName = nameToken.ValueText;
if (uniqueFieldNames.Contains(fieldName))
{
// name duplication
Error(diagnostics, ErrorCode.ERR_AnonymousTypeDuplicatePropertyName, fieldInitializer);
hasError = true;
fieldName = null;
}
else
{
uniqueFieldNames.Add(fieldName);
}
}
else
{
// there is something wrong with field's name
hasError = true;
}
// calculate the expression's type and report errors if needed
TypeSymbol fieldType = GetAnonymousTypeFieldType(boundExpressions[i], fieldInitializer, diagnostics, ref hasError);
// build anonymous type field descriptor
fieldSyntaxNodes[i] = (nameToken.CSharpKind() == SyntaxKind.IdentifierToken) ? (CSharpSyntaxNode)nameToken.Parent : fieldInitializer;
fields[i] = new AnonymousTypeField(fieldName == null ? '$' + i.ToString() : fieldName, fieldSyntaxNodes[i].Location, fieldType);
// NOTE: ERR_InvalidAnonymousTypeMemberDeclarator (CS0746) would be generated by parser if needed
}
// Create anonymous type
AnonymousTypeManager manager = this.Compilation.AnonymousTypeManager;
AnonymousTypeDescriptor descriptor = new AnonymousTypeDescriptor(fields.AsImmutableOrNull(), node.NewKeyword.GetLocation());
NamedTypeSymbol anonymousType = manager.ConstructAnonymousTypeSymbol(descriptor);
// declarators - bound nodes created for providing semantic info
// on anonymous type fields having explicitly specified name
ArrayBuilder <BoundAnonymousPropertyDeclaration> declarators =
ArrayBuilder <BoundAnonymousPropertyDeclaration> .GetInstance();
for (int i = 0; i < fieldCount; i++)
{
NameEqualsSyntax explicitName = initializers[i].NameEquals;
if (explicitName != null)
{
AnonymousTypeField field = fields[i];
if (field.Name != null)
{
// get property symbol and create a bound property declaration node
foreach (var symbol in anonymousType.GetMembers(field.Name))
{
if (symbol.Kind == SymbolKind.Property)
{
declarators.Add(new BoundAnonymousPropertyDeclaration(fieldSyntaxNodes[i], (PropertySymbol)symbol, field.Type));
break;
}
}
}
}
}
// check if anonymous object creation is allowed in this context
if (!this.IsAnonymousTypesAllowed())
{
Error(diagnostics, ErrorCode.ERR_AnonymousTypeNotAvailable, node.NewKeyword);
hasError = true;
}
// Finally create a bound node
return(new BoundAnonymousObjectCreationExpression(
node,
anonymousType.InstanceConstructors[0],
boundExpressions.AsImmutableOrNull(),
declarators.ToImmutableAndFree(),
anonymousType,
hasError));
}
/// <summary>
/// Rewrites arguments of an invocation according to the receiving method or indexer.
/// It is assumed that the each argument has already been lowered, but we may need
/// additional rewriting for the arguments, such as generating a params array, re-ordering
/// arguments based on argsToParamsOpt map, inserting arguments for optional parameters, etc.
/// 'optionalParametersMethod' is the method used for values of any optional parameters.
/// For indexers, this method must be an accessor, and for methods it must be the method
/// itself. 'optionalParametersMethod' is needed for indexers since the getter and setter
/// may have distinct optional parameter values.
/// </summary>
private ImmutableArray <BoundExpression> MakeArguments(
CSharpSyntaxNode syntax,
ImmutableArray <BoundExpression> rewrittenArguments,
Symbol methodOrIndexer,
MethodSymbol optionalParametersMethod,
bool expanded,
ImmutableArray <int> argsToParamsOpt,
ref ImmutableArray <RefKind> argumentRefKindsOpt,
out ImmutableArray <LocalSymbol> temps,
bool invokedAsExtensionMethod = false)
{
// Either the methodOrIndexer is a property, in which case the method used
// for optional parameters is an accessor of that property (or an overridden
// property), or the methodOrIndexer is used for optional parameters directly.
Debug.Assert(((methodOrIndexer.Kind == SymbolKind.Property) && optionalParametersMethod.IsAccessor()) ||
ReferenceEquals(methodOrIndexer, optionalParametersMethod));
// We need to do a fancy rewrite under the following circumstances:
// (1) a params array is being used; we need to generate the array.
// (2) there were named arguments that reordered the arguments; we might
// have to generate temporaries to ensure that the arguments are
// evaluated in source code order, not the actual call order.
// (3) there were optional parameters that had no corresponding arguments.
//
// If none of those are the case then we can just take an early out.
// An applicable "vararg" method could not possibly be applicable in its expanded
// form, and cannot possibly have named arguments or used optional parameters,
// because the __arglist() argument has to be positional and in the last position.
if (methodOrIndexer.GetIsVararg())
{
Debug.Assert(rewrittenArguments.Length == methodOrIndexer.GetParameterCount() + 1);
Debug.Assert(argsToParamsOpt.IsDefault);
Debug.Assert(!expanded);
temps = default(ImmutableArray <LocalSymbol>);
return(rewrittenArguments);
}
var receiverNamedType = invokedAsExtensionMethod ?
((MethodSymbol)methodOrIndexer).Parameters[0].Type as NamedTypeSymbol :
methodOrIndexer.ContainingType;
bool isComReceiver = (object)receiverNamedType != null && receiverNamedType.IsComImport;
if (rewrittenArguments.Length == methodOrIndexer.GetParameterCount() &&
argsToParamsOpt.IsDefault &&
!expanded &&
!isComReceiver)
{
temps = default(ImmutableArray <LocalSymbol>);
return(rewrittenArguments);
}
// We have:
// * a list of arguments, already converted to their proper types,
// in source code order. Some optional arguments might be missing.
// * a map showing which parameter each argument corresponds to. If
// this is null, then the argument to parameter mapping is one-to-one.
// * the ref kind of each argument, in source code order. That is, whether
// the argument was marked as ref, out, or value (neither).
// * a method symbol.
// * whether the call is expanded or normal form.
// We rewrite the call so that:
// * if in its expanded form, we create the params array.
// * if the call requires reordering of arguments because of named arguments, temporaries are generated as needed
// Doing this transformation can move around refness in interesting ways. For example, consider
//
// A().M(y : ref B()[C()], x : out D());
//
// This will be created as a call with receiver A(), symbol M, argument list ( B()[C()], D() ),
// name list ( y, x ) and ref list ( ref, out ). We can rewrite this into temporaries:
//
// A().M(
// seq ( ref int temp_y = ref B()[C()], out D() ),
// temp_y );
//
// Now we have a call with receiver A(), symbol M, argument list as shown, no name list,
// and ref list ( out, value ). We do not want to pass a *ref* to temp_y; the temporary
// storage is not the thing being ref'd! We want to pass the *value* of temp_y, which
// *contains* a reference.
// We attempt to minimize the number of temporaries required. Arguments which neither
// produce nor observe a side effect can be placed into their proper position without
// recourse to a temporary. For example:
//
// Where(predicate: x=>x.Length!=0, sequence: S())
//
// can be rewritten without any temporaries because the conversion from lambda to
// delegate does not produce any side effect that could be observed by S().
//
// By contrast:
//
// Foo(z: this.p, y: this.Q(), x: (object)10)
//
// The boxing of 10 can be reordered, but the fetch of this.p has to happen before the
// call to this.Q() because the call could change the value of this.p.
//
// We start by binding everything that is not obviously reorderable as a temporary, and
// then run an optimizer to remove unnecessary temporaries.
ImmutableArray <ParameterSymbol> parameters = methodOrIndexer.GetParameters();
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, argumentRefKindsOpt, rewrittenArguments, actualArguments, refKinds, storesToTemps);
// Step two: If we have a params array, build the array and fill in the argument.
if (expanded)
{
actualArguments[actualArguments.Length - 1] = BuildParamsArray(syntax, methodOrIndexer, argsToParamsOpt, rewrittenArguments, parameters, actualArguments[actualArguments.Length - 1]);
}
// Step three: Now fill in the optional arguments.
InsertMissingOptionalArguments(syntax, optionalParametersMethod.Parameters, actualArguments);
// Step four: all the arguments are now in place. Optimize away unnecessary temporaries.
// Necessary temporaries have their store instructions merged into the appropriate
// argument expression.
ArrayBuilder <LocalSymbol> temporariesBuilder = ArrayBuilder <LocalSymbol> .GetInstance();
OptimizeTemporaries(actualArguments, refKinds, storesToTemps, temporariesBuilder);
if (isComReceiver)
{
RewriteArgumentsForComCall(parameters, actualArguments, refKinds, temporariesBuilder);
}
temps = temporariesBuilder.ToImmutableAndFree();
storesToTemps.Free();
// * The refkind map is now filled out to match the arguments.
// * The list of parameter names is now null because the arguments have been reordered.
// * The args-to-params map is now null because every argument exactly matches its parameter.
// * The call is no longer in its expanded form.
argumentRefKindsOpt = GetRefKindsOrNull(refKinds);
refKinds.Free();
return(actualArguments.AsImmutableOrNull());
}
