lib/SILGen/ArgumentSource.cpp - third_party/swift - Git at Google

 //===--- ArgumentSource.cpp - Latent value representation -----------------===//
 //
 // This source file is part of the Swift.org open source project
 //
 // Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 //
 //===----------------------------------------------------------------------===//
 //
 // A structure for holding a r-value or l-value
 //
 //===----------------------------------------------------------------------===//

 #include "ArgumentSource.h"
 #include "Conversion.h"
 #include "Initialization.h"

 using namespace swift;
 using namespace Lowering;

 RValue &ArgumentSource::peekRValue() & {
   assert(isRValue() && "Undefined behavior to call this method without the "
          "ArgumentSource actually being an RValue");
   return Storage.get<RValueStorage>(StoredKind).Value;
 }

 bool ArgumentSource::isShuffle() const {
   switch (StoredKind) {
   case Kind::Invalid:
     llvm_unreachable("argument source is invalid");
   case Kind::RValue:
   case Kind::LValue:
     return false;
   case Kind::Expr:
     // FIXME: TupleShuffleExprs come in two flavors:
     //
     // 1) as apply arguments, where they're used to insert default
     // argument value and collect varargs
     //
     // 2) as tuple conversions, where they can introduce, eliminate
     // and re-order fields
     //
     // Case 1) must be emitted by ArgEmitter, and Case 2) must be
     // emitted by RValueEmitter.
     //
     // It would be good to split up TupleShuffleExpr into these two
     // cases, and simplify ArgEmitter since it no longer has to deal
     // with re-ordering.
     return isa<TupleShuffleExpr>(asKnownExpr());
   }
   llvm_unreachable("bad kind");
 }

 RValue ArgumentSource::getAsRValue(SILGenFunction &SGF, SGFContext C) && {
   switch (StoredKind) {
   case Kind::Invalid:
     llvm_unreachable("argument source is invalid");
   case Kind::LValue:
     llvm_unreachable("cannot get l-value as r-value");
   case Kind::RValue:
     return std::move(*this).asKnownRValue(SGF);
   case Kind::Expr:
     return SGF.emitRValue(std::move(*this).asKnownExpr(), C);
   }
   llvm_unreachable("bad kind");
 }

 ManagedValue ArgumentSource::getAsSingleValue(SILGenFunction &SGF,
                                               SGFContext C) && {
   switch (StoredKind) {
   case Kind::Invalid:
     llvm_unreachable("argument source is invalid");
   case Kind::LValue: {
     auto loc = getKnownLValueLocation();
     LValue &&lv = std::move(*this).asKnownLValue();
     return SGF.emitAddressOfLValue(loc, std::move(lv));
   }
   case Kind::RValue: {
     auto loc = getKnownRValueLocation();
     if (auto init = C.getEmitInto()) {
       std::move(*this).asKnownRValue(SGF)
                       .ensurePlusOne(SGF, loc)
                       .forwardInto(SGF, loc, init);
       return ManagedValue::forInContext();
     } else {
       return std::move(*this).asKnownRValue(SGF).getAsSingleValue(SGF, loc);
     }
   }
   case Kind::Expr: {
     auto e = std::move(*this).asKnownExpr();
     if (e->isSemanticallyInOutExpr()) {
       auto lv = SGF.emitLValue(e, SGFAccessKind::ReadWrite);
       return SGF.emitAddressOfLValue(e, std::move(lv));
     } else {
       return SGF.emitRValueAsSingleValue(e, C);
     }
   }
   }
   llvm_unreachable("bad kind");
 }


 ManagedValue ArgumentSource::getAsSingleValue(SILGenFunction &SGF,
                                               AbstractionPattern origFormalType,
                                               SGFContext C) && {
   auto substFormalType = getSubstRValueType();
   auto conversion = Conversion::getSubstToOrig(origFormalType, substFormalType);
   return std::move(*this).getConverted(SGF, conversion, C);
 }

 ManagedValue ArgumentSource::getConverted(SILGenFunction &SGF,
                                           const Conversion &conversion,
                                           SGFContext C) && {
   switch (StoredKind) {
   case Kind::Invalid:
     llvm_unreachable("argument source is invalid");
   case Kind::LValue:
     llvm_unreachable("cannot get converted l-value");
   case Kind::RValue:
   case Kind::Expr:
     return SGF.emitConvertedRValue(getLocation(), conversion, C,
                 [&](SILGenFunction &SGF, SILLocation loc, SGFContext C) {
       return std::move(*this).getAsSingleValue(SGF, C);
     });
   }
   llvm_unreachable("bad kind");
 }

 void ArgumentSource::forwardInto(SILGenFunction &SGF, Initialization *dest) && {
   switch (StoredKind) {
   case Kind::Invalid:
     llvm_unreachable("argument source is invalid");
   case Kind::LValue:
     llvm_unreachable("cannot forward an l-value");
   case Kind::RValue: {
     auto loc = getKnownRValueLocation();
     std::move(*this).asKnownRValue(SGF).ensurePlusOne(SGF, loc).forwardInto(SGF, loc, dest);
     return;
   }
   case Kind::Expr: {
     auto e = std::move(*this).asKnownExpr();
     SGF.emitExprInto(e, dest);
     return;
   }
   }
   llvm_unreachable("bad kind");
 }

 // FIXME: Once uncurrying is removed, get rid of this constructor.
 ArgumentSource::ArgumentSource(SILLocation loc, RValue &&rv, Kind kind)
     : Storage(), StoredKind(kind) {
   Storage.emplaceAggregate<RValueStorage>(StoredKind, std::move(rv), loc);
 }

 ArgumentSource ArgumentSource::borrow(SILGenFunction &SGF) const & {
   switch (StoredKind) {
   case Kind::Invalid:
     llvm_unreachable("argument source is invalid");
   case Kind::LValue:
     llvm_unreachable("cannot borrow an l-value");
   case Kind::RValue: {
     auto loc = getKnownRValueLocation();
     return ArgumentSource(loc, asKnownRValue().borrow(SGF, loc));
   }
   case Kind::Expr: {
     llvm_unreachable("cannot borrow an expression");
   }
   }
   llvm_unreachable("bad kind");
 }

 ManagedValue ArgumentSource::materialize(SILGenFunction &SGF) && {
   if (isRValue()) {
     auto loc = getKnownRValueLocation();
     return std::move(*this).asKnownRValue(SGF).materialize(SGF, loc);
   }

   auto loc = getLocation();
   auto temp = SGF.emitTemporary(loc, SGF.getTypeLowering(getSubstRValueType()));
   std::move(*this).forwardInto(SGF, temp.get());
   return temp->getManagedAddress();
 }

 ManagedValue ArgumentSource::materialize(SILGenFunction &SGF,
                                          AbstractionPattern origFormalType,
                                          SILType destType) && {
   auto substFormalType = getSubstRValueType();
   assert(!destType || destType.getObjectType() ==
                SGF.SGM.Types.getLoweredType(origFormalType,
                                             substFormalType).getObjectType());

   // Fast path: if the types match exactly, no abstraction difference
   // is possible and we can just materialize as normal.
   if (origFormalType.isExactType(substFormalType))
     return std::move(*this).materialize(SGF);

   auto &destTL =
     (destType ? SGF.getTypeLowering(destType)
               : SGF.getTypeLowering(origFormalType, substFormalType));
   if (!destType) destType = destTL.getLoweredType();

   // If there's no abstraction difference, we can just materialize as normal.
   if (destTL.getLoweredType() == SGF.getLoweredType(substFormalType)) {
     return std::move(*this).materialize(SGF);
   }

   // Emit a temporary at the given address.
   auto temp = SGF.emitTemporary(getLocation(), destTL);

   // Forward into it.
   std::move(*this).forwardInto(SGF, origFormalType, temp.get(), destTL);

   return temp->getManagedAddress();
 }

 void ArgumentSource::forwardInto(SILGenFunction &SGF,
                                  AbstractionPattern origFormalType,
                                  Initialization *dest,
                                  const TypeLowering &destTL) && {
   auto substFormalType = getSubstRValueType();
   assert(destTL.getLoweredType() ==
                         SGF.getLoweredType(origFormalType, substFormalType));

   // If there are no abstraction changes, we can just forward
   // normally.
   if (origFormalType.isExactType(substFormalType) ||
       destTL.getLoweredType() == SGF.getLoweredType(substFormalType)) {
     std::move(*this).forwardInto(SGF, dest);
     return;
   }

   // Otherwise, emit as a single independent value.
   SILLocation loc = getLocation();
   ManagedValue outputValue =
       std::move(*this).getAsSingleValue(SGF, origFormalType,
                                         SGFContext(dest));

   if (outputValue.isInContext()) return;

   // Use RValue's forward-into-initialization code.  We have to lie to
   // RValue about the formal type (by using the lowered type) because
   // we're emitting into an abstracted value, which RValue doesn't
   // really handle.
   auto substLoweredType = destTL.getLoweredType().getASTType();
   RValue(SGF, loc, substLoweredType, outputValue).forwardInto(SGF, loc, dest);
 }

 void ArgumentSource::dump() const {
   dump(llvm::errs());
 }

 void ArgumentSource::dump(raw_ostream &out, unsigned indent) const {
   out.indent(indent) << "ArgumentSource::";
   switch (StoredKind) {
   case Kind::Invalid:
     out << "Invalid\n";
     return;
   case Kind::LValue:
     out << "LValue\n";
     Storage.get<LValueStorage>(StoredKind).Value.dump(out, indent + 2);
     return;
   case Kind::RValue:
     out << "RValue\n";
     Storage.get<RValueStorage>(StoredKind).Value.dump(out, indent + 2);
     return;
   case Kind::Expr:
     out << "Expr\n";
     Storage.get<Expr*>(StoredKind)->dump(out); // FIXME: indent
     out << "\n";
     return;
   }
   llvm_unreachable("bad kind");
 }

 void PreparedArguments::emplaceEmptyArgumentList(SILGenFunction &SGF) {
   emplace({}, /*scalar*/ false);
   assert(isValid());
 }

 PreparedArguments
 PreparedArguments::copy(SILGenFunction &SGF, SILLocation loc) const {
   if (isNull()) return PreparedArguments();

   assert(isValid());
   PreparedArguments result(getParams(), isScalar());
   for (auto &elt : Arguments) {
     assert(elt.isRValue());
     result.add(elt.getKnownRValueLocation(),
                elt.asKnownRValue().copy(SGF, loc));
   }
   assert(isValid());
   return result;
 }

 bool PreparedArguments::isObviouslyEqual(const PreparedArguments &other) const {
   if (isNull() != other.isNull())
     return false;
   if (isNull())
     return true;

   assert(isValid() && other.isValid());
   if (Arguments.size() != other.Arguments.size())
     return false;
   for (auto i : indices(Arguments)) {
     if (!Arguments[i].isObviouslyEqual(other.Arguments[i]))
       return false;
   }
   return true;
 }

 bool ArgumentSource::isObviouslyEqual(const ArgumentSource &other) const {
   if (StoredKind != other.StoredKind)
     return false;

   switch (StoredKind) {
   case Kind::Invalid:
     llvm_unreachable("argument source is invalid");
   case Kind::RValue:
     return asKnownRValue().isObviouslyEqual(other.asKnownRValue());
   case Kind::LValue:
     return false; // TODO?
   case Kind::Expr:
     return false; // TODO?
   }
   llvm_unreachable("bad kind");
 }

 PreparedArguments PreparedArguments::copyForDiagnostics() const {
   if (isNull())
     return PreparedArguments();

   assert(isValid());
   PreparedArguments result(getParams(), isScalar());
   for (auto &arg : Arguments) {
     result.Arguments.push_back(arg.copyForDiagnostics());
   }
   return result;
 }

 ArgumentSource ArgumentSource::copyForDiagnostics() const {
   switch (StoredKind) {
   case Kind::Invalid:
     return ArgumentSource();
   case Kind::LValue:
     // We have no way to copy an l-value for diagnostics.
     return {getKnownLValueLocation(), LValue()};
   case Kind::RValue:
     return {getKnownRValueLocation(), asKnownRValue().copyForDiagnostics()};
   case Kind::Expr:
     return asKnownExpr();
   }
   llvm_unreachable("bad kind");
 }
	//===--- ArgumentSource.cpp - Latent value representation -----------------===//
	//
	// This source file is part of the Swift.org open source project
	//
	// Copyright (c) 2014 - 2017 Apple Inc. and the Swift project authors
	// Licensed under Apache License v2.0 with Runtime Library Exception
	//
	// See https://swift.org/LICENSE.txt for license information
	// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
	//
	//===----------------------------------------------------------------------===//
	//
	// A structure for holding a r-value or l-value
	//
	//===----------------------------------------------------------------------===//

	#include "ArgumentSource.h"
	#include "Conversion.h"
	#include "Initialization.h"

	using namespace swift;
	using namespace Lowering;

	RValue &ArgumentSource::peekRValue() & {
	assert(isRValue() && "Undefined behavior to call this method without the "
	"ArgumentSource actually being an RValue");
	return Storage.get<RValueStorage>(StoredKind).Value;
	}

	bool ArgumentSource::isShuffle() const {
	switch (StoredKind) {
	case Kind::Invalid:
	llvm_unreachable("argument source is invalid");
	case Kind::RValue:
	case Kind::LValue:
	return false;
	case Kind::Expr:
	// FIXME: TupleShuffleExprs come in two flavors:
	//
	// 1) as apply arguments, where they're used to insert default
	// argument value and collect varargs
	//
	// 2) as tuple conversions, where they can introduce, eliminate
	// and re-order fields
	//
	// Case 1) must be emitted by ArgEmitter, and Case 2) must be
	// emitted by RValueEmitter.
	//
	// It would be good to split up TupleShuffleExpr into these two
	// cases, and simplify ArgEmitter since it no longer has to deal
	// with re-ordering.
	return isa<TupleShuffleExpr>(asKnownExpr());
	}
	llvm_unreachable("bad kind");
	}

	RValue ArgumentSource::getAsRValue(SILGenFunction &SGF, SGFContext C) && {
	switch (StoredKind) {
	case Kind::Invalid:
	llvm_unreachable("argument source is invalid");
	case Kind::LValue:
	llvm_unreachable("cannot get l-value as r-value");
	case Kind::RValue:
	return std::move(*this).asKnownRValue(SGF);
	case Kind::Expr:
	return SGF.emitRValue(std::move(*this).asKnownExpr(), C);
	}
	llvm_unreachable("bad kind");
	}

	ManagedValue ArgumentSource::getAsSingleValue(SILGenFunction &SGF,
	SGFContext C) && {
	switch (StoredKind) {
	case Kind::Invalid:
	llvm_unreachable("argument source is invalid");
	case Kind::LValue: {
	auto loc = getKnownLValueLocation();
	LValue &&lv = std::move(*this).asKnownLValue();
	return SGF.emitAddressOfLValue(loc, std::move(lv));
	}
	case Kind::RValue: {
	auto loc = getKnownRValueLocation();
	if (auto init = C.getEmitInto()) {
	std::move(*this).asKnownRValue(SGF)
	.ensurePlusOne(SGF, loc)
	.forwardInto(SGF, loc, init);
	return ManagedValue::forInContext();
	} else {
	return std::move(*this).asKnownRValue(SGF).getAsSingleValue(SGF, loc);
	}
	}
	case Kind::Expr: {
	auto e = std::move(*this).asKnownExpr();
	if (e->isSemanticallyInOutExpr()) {
	auto lv = SGF.emitLValue(e, SGFAccessKind::ReadWrite);
	return SGF.emitAddressOfLValue(e, std::move(lv));
	} else {
	return SGF.emitRValueAsSingleValue(e, C);
	}
	}
	}
	llvm_unreachable("bad kind");
	}


	ManagedValue ArgumentSource::getAsSingleValue(SILGenFunction &SGF,
	AbstractionPattern origFormalType,
	SGFContext C) && {
	auto substFormalType = getSubstRValueType();
	auto conversion = Conversion::getSubstToOrig(origFormalType, substFormalType);
	return std::move(*this).getConverted(SGF, conversion, C);
	}

	ManagedValue ArgumentSource::getConverted(SILGenFunction &SGF,
	const Conversion &conversion,
	SGFContext C) && {
	switch (StoredKind) {
	case Kind::Invalid:
	llvm_unreachable("argument source is invalid");
	case Kind::LValue:
	llvm_unreachable("cannot get converted l-value");
	case Kind::RValue:
	case Kind::Expr:
	return SGF.emitConvertedRValue(getLocation(), conversion, C,
	[&](SILGenFunction &SGF, SILLocation loc, SGFContext C) {
	return std::move(*this).getAsSingleValue(SGF, C);
	});
	}
	llvm_unreachable("bad kind");
	}

	void ArgumentSource::forwardInto(SILGenFunction &SGF, Initialization *dest) && {
	switch (StoredKind) {
	case Kind::Invalid:
	llvm_unreachable("argument source is invalid");
	case Kind::LValue:
	llvm_unreachable("cannot forward an l-value");
	case Kind::RValue: {
	auto loc = getKnownRValueLocation();
	std::move(*this).asKnownRValue(SGF).ensurePlusOne(SGF, loc).forwardInto(SGF, loc, dest);
	return;
	}
	case Kind::Expr: {
	auto e = std::move(*this).asKnownExpr();
	SGF.emitExprInto(e, dest);
	return;
	}
	}
	llvm_unreachable("bad kind");
	}

	// FIXME: Once uncurrying is removed, get rid of this constructor.
	ArgumentSource::ArgumentSource(SILLocation loc, RValue &&rv, Kind kind)
	: Storage(), StoredKind(kind) {
	Storage.emplaceAggregate<RValueStorage>(StoredKind, std::move(rv), loc);
	}

	ArgumentSource ArgumentSource::borrow(SILGenFunction &SGF) const & {
	switch (StoredKind) {
	case Kind::Invalid:
	llvm_unreachable("argument source is invalid");
	case Kind::LValue:
	llvm_unreachable("cannot borrow an l-value");
	case Kind::RValue: {
	auto loc = getKnownRValueLocation();
	return ArgumentSource(loc, asKnownRValue().borrow(SGF, loc));
	}
	case Kind::Expr: {
	llvm_unreachable("cannot borrow an expression");
	}
	}
	llvm_unreachable("bad kind");
	}

	ManagedValue ArgumentSource::materialize(SILGenFunction &SGF) && {
	if (isRValue()) {
	auto loc = getKnownRValueLocation();
	return std::move(*this).asKnownRValue(SGF).materialize(SGF, loc);
	}

	auto loc = getLocation();
	auto temp = SGF.emitTemporary(loc, SGF.getTypeLowering(getSubstRValueType()));
	std::move(*this).forwardInto(SGF, temp.get());
	return temp->getManagedAddress();
	}

	ManagedValue ArgumentSource::materialize(SILGenFunction &SGF,
	AbstractionPattern origFormalType,
	SILType destType) && {
	auto substFormalType = getSubstRValueType();
	assert(!destType \|\| destType.getObjectType() ==
	SGF.SGM.Types.getLoweredType(origFormalType,
	substFormalType).getObjectType());

	// Fast path: if the types match exactly, no abstraction difference
	// is possible and we can just materialize as normal.
	if (origFormalType.isExactType(substFormalType))
	return std::move(*this).materialize(SGF);

	auto &destTL =
	(destType ? SGF.getTypeLowering(destType)
	: SGF.getTypeLowering(origFormalType, substFormalType));
	if (!destType) destType = destTL.getLoweredType();

	// If there's no abstraction difference, we can just materialize as normal.
	if (destTL.getLoweredType() == SGF.getLoweredType(substFormalType)) {
	return std::move(*this).materialize(SGF);
	}

	// Emit a temporary at the given address.
	auto temp = SGF.emitTemporary(getLocation(), destTL);

	// Forward into it.
	std::move(*this).forwardInto(SGF, origFormalType, temp.get(), destTL);

	return temp->getManagedAddress();
	}

	void ArgumentSource::forwardInto(SILGenFunction &SGF,
	AbstractionPattern origFormalType,
	Initialization *dest,
	const TypeLowering &destTL) && {
	auto substFormalType = getSubstRValueType();
	assert(destTL.getLoweredType() ==
	SGF.getLoweredType(origFormalType, substFormalType));

	// If there are no abstraction changes, we can just forward
	// normally.
	if (origFormalType.isExactType(substFormalType) \|\|
	destTL.getLoweredType() == SGF.getLoweredType(substFormalType)) {
	std::move(*this).forwardInto(SGF, dest);
	return;
	}

	// Otherwise, emit as a single independent value.
	SILLocation loc = getLocation();
	ManagedValue outputValue =
	std::move(*this).getAsSingleValue(SGF, origFormalType,
	SGFContext(dest));

	if (outputValue.isInContext()) return;

	// Use RValue's forward-into-initialization code. We have to lie to
	// RValue about the formal type (by using the lowered type) because
	// we're emitting into an abstracted value, which RValue doesn't
	// really handle.
	auto substLoweredType = destTL.getLoweredType().getASTType();
	RValue(SGF, loc, substLoweredType, outputValue).forwardInto(SGF, loc, dest);
	}

	void ArgumentSource::dump() const {
	dump(llvm::errs());
	}

	void ArgumentSource::dump(raw_ostream &out, unsigned indent) const {
	out.indent(indent) << "ArgumentSource::";
	switch (StoredKind) {
	case Kind::Invalid:
	out << "Invalid\n";
	return;
	case Kind::LValue:
	out << "LValue\n";
	Storage.get<LValueStorage>(StoredKind).Value.dump(out, indent + 2);
	return;
	case Kind::RValue:
	out << "RValue\n";
	Storage.get<RValueStorage>(StoredKind).Value.dump(out, indent + 2);
	return;
	case Kind::Expr:
	out << "Expr\n";
	Storage.get<Expr*>(StoredKind)->dump(out); // FIXME: indent
	out << "\n";
	return;
	}
	llvm_unreachable("bad kind");
	}

	void PreparedArguments::emplaceEmptyArgumentList(SILGenFunction &SGF) {
	emplace({}, /scalar/ false);
	assert(isValid());
	}

	PreparedArguments
	PreparedArguments::copy(SILGenFunction &SGF, SILLocation loc) const {
	if (isNull()) return PreparedArguments();

	assert(isValid());
	PreparedArguments result(getParams(), isScalar());
	for (auto &elt : Arguments) {
	assert(elt.isRValue());
	result.add(elt.getKnownRValueLocation(),
	elt.asKnownRValue().copy(SGF, loc));
	}
	assert(isValid());
	return result;
	}

	bool PreparedArguments::isObviouslyEqual(const PreparedArguments &other) const {
	if (isNull() != other.isNull())
	return false;
	if (isNull())
	return true;

	assert(isValid() && other.isValid());
	if (Arguments.size() != other.Arguments.size())
	return false;
	for (auto i : indices(Arguments)) {
	if (!Arguments[i].isObviouslyEqual(other.Arguments[i]))
	return false;
	}
	return true;
	}

	bool ArgumentSource::isObviouslyEqual(const ArgumentSource &other) const {
	if (StoredKind != other.StoredKind)
	return false;

	switch (StoredKind) {
	case Kind::Invalid:
	llvm_unreachable("argument source is invalid");
	case Kind::RValue:
	return asKnownRValue().isObviouslyEqual(other.asKnownRValue());
	case Kind::LValue:
	return false; // TODO?
	case Kind::Expr:
	return false; // TODO?
	}
	llvm_unreachable("bad kind");
	}

	PreparedArguments PreparedArguments::copyForDiagnostics() const {
	if (isNull())
	return PreparedArguments();

	assert(isValid());
	PreparedArguments result(getParams(), isScalar());
	for (auto &arg : Arguments) {
	result.Arguments.push_back(arg.copyForDiagnostics());
	}
	return result;
	}

	ArgumentSource ArgumentSource::copyForDiagnostics() const {
	switch (StoredKind) {
	case Kind::Invalid:
	return ArgumentSource();
	case Kind::LValue:
	// We have no way to copy an l-value for diagnostics.
	return {getKnownLValueLocation(), LValue()};
	case Kind::RValue:
	return {getKnownRValueLocation(), asKnownRValue().copyForDiagnostics()};
	case Kind::Expr:
	return asKnownExpr();
	}
	llvm_unreachable("bad kind");
	}