llvm/lib/ProfileData/PGOCtxProfWriter.cpp - llvm-project.git - Git at Google

 //===- PGOCtxProfWriter.cpp - Contextual Instrumentation profile writer ---===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // Write a contextual profile to bitstream.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/ProfileData/PGOCtxProfWriter.h"
 #include "llvm/Bitstream/BitCodeEnums.h"
 #include "llvm/ProfileData/CtxInstrContextNode.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"

 using namespace llvm;
 using namespace llvm::ctx_profile;

 static cl::opt<bool>
     IncludeEmptyOpt("ctx-prof-include-empty", cl::init(false),
                     cl::desc("Also write profiles with all-zero counters. "
                              "Intended for testing/debugging."));

 PGOCtxProfileWriter::PGOCtxProfileWriter(
     raw_ostream &Out, std::optional<unsigned> VersionOverride,
     bool IncludeEmpty)
     : Writer(Out, 0),
       IncludeEmpty(IncludeEmptyOpt.getNumOccurrences() > 0 ? IncludeEmptyOpt
                                                            : IncludeEmpty) {
   static_assert(ContainerMagic.size() == 4);
   Out.write(ContainerMagic.data(), ContainerMagic.size());
   Writer.EnterBlockInfoBlock();
   {
     auto DescribeBlock = [&](unsigned ID, StringRef Name) {
       Writer.EmitRecord(bitc::BLOCKINFO_CODE_SETBID,
                         SmallVector<unsigned, 1>{ID});
       Writer.EmitRecord(bitc::BLOCKINFO_CODE_BLOCKNAME,
                         llvm::arrayRefFromStringRef(Name));
     };
     SmallVector<uint64_t, 16> Data;
     auto DescribeRecord = [&](unsigned RecordID, StringRef Name) {
       Data.clear();
       Data.push_back(RecordID);
       llvm::append_range(Data, Name);
       Writer.EmitRecord(bitc::BLOCKINFO_CODE_SETRECORDNAME, Data);
     };
     DescribeBlock(PGOCtxProfileBlockIDs::ProfileMetadataBlockID, "Metadata");
     DescribeRecord(PGOCtxProfileRecords::Version, "Version");
     DescribeBlock(PGOCtxProfileBlockIDs::ContextsSectionBlockID, "Contexts");
     DescribeBlock(PGOCtxProfileBlockIDs::ContextRootBlockID, "Root");
     DescribeRecord(PGOCtxProfileRecords::Guid, "GUID");
     DescribeRecord(PGOCtxProfileRecords::TotalRootEntryCount,
                    "TotalRootEntryCount");
     DescribeRecord(PGOCtxProfileRecords::Counters, "Counters");
     DescribeBlock(PGOCtxProfileBlockIDs::UnhandledBlockID, "Unhandled");
     DescribeBlock(PGOCtxProfileBlockIDs::ContextNodeBlockID, "Context");
     DescribeRecord(PGOCtxProfileRecords::Guid, "GUID");
     DescribeRecord(PGOCtxProfileRecords::CallsiteIndex, "CalleeIndex");
     DescribeRecord(PGOCtxProfileRecords::Counters, "Counters");
     DescribeBlock(PGOCtxProfileBlockIDs::FlatProfilesSectionBlockID,
                   "FlatProfiles");
     DescribeBlock(PGOCtxProfileBlockIDs::FlatProfileBlockID, "Flat");
     DescribeRecord(PGOCtxProfileRecords::Guid, "GUID");
     DescribeRecord(PGOCtxProfileRecords::Counters, "Counters");
   }
   Writer.ExitBlock();
   Writer.EnterSubblock(PGOCtxProfileBlockIDs::ProfileMetadataBlockID, CodeLen);
   const auto Version = VersionOverride.value_or(CurrentVersion);
   Writer.EmitRecord(PGOCtxProfileRecords::Version,
                     SmallVector<unsigned, 1>({Version}));
 }

 void PGOCtxProfileWriter::writeCounters(ArrayRef<uint64_t> Counters) {
   Writer.EmitCode(bitc::UNABBREV_RECORD);
   Writer.EmitVBR(PGOCtxProfileRecords::Counters, VBREncodingBits);
   Writer.EmitVBR(Counters.size(), VBREncodingBits);
   for (uint64_t C : Counters)
     Writer.EmitVBR64(C, VBREncodingBits);
 }

 void PGOCtxProfileWriter::writeGuid(ctx_profile::GUID Guid) {
   Writer.EmitRecord(PGOCtxProfileRecords::Guid, SmallVector<uint64_t, 1>{Guid});
 }

 void PGOCtxProfileWriter::writeCallsiteIndex(uint32_t CallsiteIndex) {
   Writer.EmitRecord(PGOCtxProfileRecords::CallsiteIndex,
                     SmallVector<uint64_t, 1>{CallsiteIndex});
 }

 void PGOCtxProfileWriter::writeRootEntryCount(uint64_t TotalRootEntryCount) {
   Writer.EmitRecord(PGOCtxProfileRecords::TotalRootEntryCount,
                     SmallVector<uint64_t, 1>{TotalRootEntryCount});
 }

 // recursively write all the subcontexts. We do need to traverse depth first to
 // model the context->subcontext implicitly, and since this captures call
 // stacks, we don't really need to be worried about stack overflow and we can
 // keep the implementation simple.
 void PGOCtxProfileWriter::writeNode(uint32_t CallsiteIndex,
                                     const ContextNode &Node) {
   // A node with no counters is an error. We don't expect this to happen from
   // the runtime, rather, this is interesting for testing the reader.
   if (!IncludeEmpty && (Node.counters_size() > 0 && Node.entrycount() == 0))
     return;
   Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextNodeBlockID, CodeLen);
   writeGuid(Node.guid());
   writeCallsiteIndex(CallsiteIndex);
   writeCounters({Node.counters(), Node.counters_size()});
   writeSubcontexts(Node);
   Writer.ExitBlock();
 }

 void PGOCtxProfileWriter::writeSubcontexts(const ContextNode &Node) {
   for (uint32_t I = 0U; I < Node.callsites_size(); ++I)
     for (const auto *Subcontext = Node.subContexts()[I]; Subcontext;
          Subcontext = Subcontext->next())
       writeNode(I, *Subcontext);
 }

 void PGOCtxProfileWriter::startContextSection() {
   Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextsSectionBlockID, CodeLen);
 }

 void PGOCtxProfileWriter::startFlatSection() {
   Writer.EnterSubblock(PGOCtxProfileBlockIDs::FlatProfilesSectionBlockID,
                        CodeLen);
 }

 void PGOCtxProfileWriter::endContextSection() { Writer.ExitBlock(); }
 void PGOCtxProfileWriter::endFlatSection() { Writer.ExitBlock(); }

 void PGOCtxProfileWriter::writeContextual(const ContextNode &RootNode,
                                           const ContextNode *Unhandled,
                                           uint64_t TotalRootEntryCount) {
   if (!IncludeEmpty && (!TotalRootEntryCount || (RootNode.counters_size() > 0 &&
                                                  RootNode.entrycount() == 0)))
     return;
   Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextRootBlockID, CodeLen);
   writeGuid(RootNode.guid());
   writeRootEntryCount(TotalRootEntryCount);
   writeCounters({RootNode.counters(), RootNode.counters_size()});

   Writer.EnterSubblock(PGOCtxProfileBlockIDs::UnhandledBlockID, CodeLen);
   for (const auto *P = Unhandled; P; P = P->next())
     writeFlat(P->guid(), P->counters(), P->counters_size());
   Writer.ExitBlock();

   writeSubcontexts(RootNode);
   Writer.ExitBlock();
 }

 void PGOCtxProfileWriter::writeFlat(ctx_profile::GUID Guid,
                                     const uint64_t *Buffer, size_t Size) {
   Writer.EnterSubblock(PGOCtxProfileBlockIDs::FlatProfileBlockID, CodeLen);
   writeGuid(Guid);
   writeCounters({Buffer, Size});
   Writer.ExitBlock();
 }

 namespace {

 /// Representation of the context node suitable for yaml serialization /
 /// deserialization.
 using SerializableFlatProfileRepresentation =
     std::pair<ctx_profile::GUID, std::vector<uint64_t>>;

 struct SerializableCtxRepresentation {
   ctx_profile::GUID Guid = 0;
   std::vector<uint64_t> Counters;
   std::vector<std::vector<SerializableCtxRepresentation>> Callsites;
 };

 struct SerializableRootRepresentation : public SerializableCtxRepresentation {
   uint64_t TotalRootEntryCount = 0;
   std::vector<SerializableFlatProfileRepresentation> Unhandled;
 };

 struct SerializableProfileRepresentation {
   std::vector<SerializableRootRepresentation> Contexts;
   std::vector<SerializableFlatProfileRepresentation> FlatProfiles;
 };

 ctx_profile::ContextNode *
 createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
            const std::vector<SerializableCtxRepresentation> &DCList);

 // Convert a DeserializableCtx into a ContextNode, potentially linking it to
 // its sibling (e.g. callee at same callsite) "Next".
 ctx_profile::ContextNode *
 createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
            const SerializableCtxRepresentation &DC,
            ctx_profile::ContextNode *Next = nullptr) {
   auto AllocSize = ctx_profile::ContextNode::getAllocSize(DC.Counters.size(),
                                                           DC.Callsites.size());
   auto *Mem = Nodes.emplace_back(std::make_unique<char[]>(AllocSize)).get();
   std::memset(Mem, 0, AllocSize);
   auto *Ret = new (Mem) ctx_profile::ContextNode(DC.Guid, DC.Counters.size(),
                                                  DC.Callsites.size(), Next);
   std::memcpy(Ret->counters(), DC.Counters.data(),
               sizeof(uint64_t) * DC.Counters.size());
   for (const auto &[I, DCList] : llvm::enumerate(DC.Callsites))
     Ret->subContexts()[I] = createNode(Nodes, DCList);
   return Ret;
 }

 // Convert a list of SerializableCtxRepresentation into a linked list of
 // ContextNodes.
 ctx_profile::ContextNode *
 createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
            const std::vector<SerializableCtxRepresentation> &DCList) {
   ctx_profile::ContextNode *List = nullptr;
   for (const auto &DC : DCList)
     List = createNode(Nodes, DC, List);
   return List;
 }
 } // namespace

 LLVM_YAML_IS_SEQUENCE_VECTOR(SerializableCtxRepresentation)
 LLVM_YAML_IS_SEQUENCE_VECTOR(std::vector<SerializableCtxRepresentation>)
 LLVM_YAML_IS_SEQUENCE_VECTOR(SerializableRootRepresentation)
 LLVM_YAML_IS_SEQUENCE_VECTOR(SerializableFlatProfileRepresentation)
 template <> struct yaml::MappingTraits<SerializableCtxRepresentation> {
   static void mapping(yaml::IO &IO, SerializableCtxRepresentation &SCR) {
     IO.mapRequired("Guid", SCR.Guid);
     IO.mapRequired("Counters", SCR.Counters);
     IO.mapOptional("Callsites", SCR.Callsites);
   }
 };

 template <> struct yaml::MappingTraits<SerializableRootRepresentation> {
   static void mapping(yaml::IO &IO, SerializableRootRepresentation &R) {
     yaml::MappingTraits<SerializableCtxRepresentation>::mapping(IO, R);
     IO.mapRequired("TotalRootEntryCount", R.TotalRootEntryCount);
     IO.mapOptional("Unhandled", R.Unhandled);
   }
 };

 template <> struct yaml::MappingTraits<SerializableProfileRepresentation> {
   static void mapping(yaml::IO &IO, SerializableProfileRepresentation &SPR) {
     IO.mapOptional("Contexts", SPR.Contexts);
     IO.mapOptional("FlatProfiles", SPR.FlatProfiles);
   }
 };

 template <> struct yaml::MappingTraits<SerializableFlatProfileRepresentation> {
   static void mapping(yaml::IO &IO,
                       SerializableFlatProfileRepresentation &SFPR) {
     IO.mapRequired("Guid", SFPR.first);
     IO.mapRequired("Counters", SFPR.second);
   }
 };

 Error llvm::createCtxProfFromYAML(StringRef Profile, raw_ostream &Out) {
   yaml::Input In(Profile);
   SerializableProfileRepresentation SPR;
   In >> SPR;
   if (In.error())
     return createStringError(In.error(), "incorrect yaml content");
   std::vector<std::unique_ptr<char[]>> Nodes;
   std::error_code EC;
   if (EC)
     return createStringError(EC, "failed to open output");
   PGOCtxProfileWriter Writer(Out);

   if (!SPR.Contexts.empty()) {
     Writer.startContextSection();
     for (const auto &DC : SPR.Contexts) {
       auto *TopList = createNode(Nodes, DC);
       if (!TopList)
         return createStringError(
             "Unexpected error converting internal structure to ctx profile");

       ctx_profile::ContextNode *FirstUnhandled = nullptr;
       for (const auto &U : DC.Unhandled) {
         SerializableCtxRepresentation Unhandled;
         Unhandled.Guid = U.first;
         Unhandled.Counters = U.second;
         FirstUnhandled = createNode(Nodes, Unhandled, FirstUnhandled);
       }
       Writer.writeContextual(*TopList, FirstUnhandled, DC.TotalRootEntryCount);
     }
     Writer.endContextSection();
   }
   if (!SPR.FlatProfiles.empty()) {
     Writer.startFlatSection();
     for (const auto &[Guid, Counters] : SPR.FlatProfiles)
       Writer.writeFlat(Guid, Counters.data(), Counters.size());
     Writer.endFlatSection();
   }
   if (EC)
     return createStringError(EC, "failed to write output");
   return Error::success();
 }
	//===- PGOCtxProfWriter.cpp - Contextual Instrumentation profile writer ---===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//
	//
	// Write a contextual profile to bitstream.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/ProfileData/PGOCtxProfWriter.h"
	#include "llvm/Bitstream/BitCodeEnums.h"
	#include "llvm/ProfileData/CtxInstrContextNode.h"
	#include "llvm/Support/CommandLine.h"
	#include "llvm/Support/Error.h"
	#include "llvm/Support/YAMLTraits.h"
	#include "llvm/Support/raw_ostream.h"

	using namespace llvm;
	using namespace llvm::ctx_profile;

	static cl::opt<bool>
	IncludeEmptyOpt("ctx-prof-include-empty", cl::init(false),
	cl::desc("Also write profiles with all-zero counters. "
	"Intended for testing/debugging."));

	PGOCtxProfileWriter::PGOCtxProfileWriter(
	raw_ostream &Out, std::optional<unsigned> VersionOverride,
	bool IncludeEmpty)
	: Writer(Out, 0),
	IncludeEmpty(IncludeEmptyOpt.getNumOccurrences() > 0 ? IncludeEmptyOpt
	: IncludeEmpty) {
	static_assert(ContainerMagic.size() == 4);
	Out.write(ContainerMagic.data(), ContainerMagic.size());
	Writer.EnterBlockInfoBlock();
	{
	auto DescribeBlock = [&](unsigned ID, StringRef Name) {
	Writer.EmitRecord(bitc::BLOCKINFO_CODE_SETBID,
	SmallVector<unsigned, 1>{ID});
	Writer.EmitRecord(bitc::BLOCKINFO_CODE_BLOCKNAME,
	llvm::arrayRefFromStringRef(Name));
	};
	SmallVector<uint64_t, 16> Data;
	auto DescribeRecord = [&](unsigned RecordID, StringRef Name) {
	Data.clear();
	Data.push_back(RecordID);
	llvm::append_range(Data, Name);
	Writer.EmitRecord(bitc::BLOCKINFO_CODE_SETRECORDNAME, Data);
	};
	DescribeBlock(PGOCtxProfileBlockIDs::ProfileMetadataBlockID, "Metadata");
	DescribeRecord(PGOCtxProfileRecords::Version, "Version");
	DescribeBlock(PGOCtxProfileBlockIDs::ContextsSectionBlockID, "Contexts");
	DescribeBlock(PGOCtxProfileBlockIDs::ContextRootBlockID, "Root");
	DescribeRecord(PGOCtxProfileRecords::Guid, "GUID");
	DescribeRecord(PGOCtxProfileRecords::TotalRootEntryCount,
	"TotalRootEntryCount");
	DescribeRecord(PGOCtxProfileRecords::Counters, "Counters");
	DescribeBlock(PGOCtxProfileBlockIDs::UnhandledBlockID, "Unhandled");
	DescribeBlock(PGOCtxProfileBlockIDs::ContextNodeBlockID, "Context");
	DescribeRecord(PGOCtxProfileRecords::Guid, "GUID");
	DescribeRecord(PGOCtxProfileRecords::CallsiteIndex, "CalleeIndex");
	DescribeRecord(PGOCtxProfileRecords::Counters, "Counters");
	DescribeBlock(PGOCtxProfileBlockIDs::FlatProfilesSectionBlockID,
	"FlatProfiles");
	DescribeBlock(PGOCtxProfileBlockIDs::FlatProfileBlockID, "Flat");
	DescribeRecord(PGOCtxProfileRecords::Guid, "GUID");
	DescribeRecord(PGOCtxProfileRecords::Counters, "Counters");
	}
	Writer.ExitBlock();
	Writer.EnterSubblock(PGOCtxProfileBlockIDs::ProfileMetadataBlockID, CodeLen);
	const auto Version = VersionOverride.value_or(CurrentVersion);
	Writer.EmitRecord(PGOCtxProfileRecords::Version,
	SmallVector<unsigned, 1>({Version}));
	}

	void PGOCtxProfileWriter::writeCounters(ArrayRef<uint64_t> Counters) {
	Writer.EmitCode(bitc::UNABBREV_RECORD);
	Writer.EmitVBR(PGOCtxProfileRecords::Counters, VBREncodingBits);
	Writer.EmitVBR(Counters.size(), VBREncodingBits);
	for (uint64_t C : Counters)
	Writer.EmitVBR64(C, VBREncodingBits);
	}

	void PGOCtxProfileWriter::writeGuid(ctx_profile::GUID Guid) {
	Writer.EmitRecord(PGOCtxProfileRecords::Guid, SmallVector<uint64_t, 1>{Guid});
	}

	void PGOCtxProfileWriter::writeCallsiteIndex(uint32_t CallsiteIndex) {
	Writer.EmitRecord(PGOCtxProfileRecords::CallsiteIndex,
	SmallVector<uint64_t, 1>{CallsiteIndex});
	}

	void PGOCtxProfileWriter::writeRootEntryCount(uint64_t TotalRootEntryCount) {
	Writer.EmitRecord(PGOCtxProfileRecords::TotalRootEntryCount,
	SmallVector<uint64_t, 1>{TotalRootEntryCount});
	}

	// recursively write all the subcontexts. We do need to traverse depth first to
	// model the context->subcontext implicitly, and since this captures call
	// stacks, we don't really need to be worried about stack overflow and we can
	// keep the implementation simple.
	void PGOCtxProfileWriter::writeNode(uint32_t CallsiteIndex,
	const ContextNode &Node) {
	// A node with no counters is an error. We don't expect this to happen from
	// the runtime, rather, this is interesting for testing the reader.
	if (!IncludeEmpty && (Node.counters_size() > 0 && Node.entrycount() == 0))
	return;
	Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextNodeBlockID, CodeLen);
	writeGuid(Node.guid());
	writeCallsiteIndex(CallsiteIndex);
	writeCounters({Node.counters(), Node.counters_size()});
	writeSubcontexts(Node);
	Writer.ExitBlock();
	}

	void PGOCtxProfileWriter::writeSubcontexts(const ContextNode &Node) {
	for (uint32_t I = 0U; I < Node.callsites_size(); ++I)
	for (const auto *Subcontext = Node.subContexts()[I]; Subcontext;
	Subcontext = Subcontext->next())
	writeNode(I, *Subcontext);
	}

	void PGOCtxProfileWriter::startContextSection() {
	Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextsSectionBlockID, CodeLen);
	}

	void PGOCtxProfileWriter::startFlatSection() {
	Writer.EnterSubblock(PGOCtxProfileBlockIDs::FlatProfilesSectionBlockID,
	CodeLen);
	}

	void PGOCtxProfileWriter::endContextSection() { Writer.ExitBlock(); }
	void PGOCtxProfileWriter::endFlatSection() { Writer.ExitBlock(); }

	void PGOCtxProfileWriter::writeContextual(const ContextNode &RootNode,
	const ContextNode *Unhandled,
	uint64_t TotalRootEntryCount) {
	if (!IncludeEmpty && (!TotalRootEntryCount \|\| (RootNode.counters_size() > 0 &&
	RootNode.entrycount() == 0)))
	return;
	Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextRootBlockID, CodeLen);
	writeGuid(RootNode.guid());
	writeRootEntryCount(TotalRootEntryCount);
	writeCounters({RootNode.counters(), RootNode.counters_size()});

	Writer.EnterSubblock(PGOCtxProfileBlockIDs::UnhandledBlockID, CodeLen);
	for (const auto *P = Unhandled; P; P = P->next())
	writeFlat(P->guid(), P->counters(), P->counters_size());
	Writer.ExitBlock();

	writeSubcontexts(RootNode);
	Writer.ExitBlock();
	}

	void PGOCtxProfileWriter::writeFlat(ctx_profile::GUID Guid,
	const uint64_t *Buffer, size_t Size) {
	Writer.EnterSubblock(PGOCtxProfileBlockIDs::FlatProfileBlockID, CodeLen);
	writeGuid(Guid);
	writeCounters({Buffer, Size});
	Writer.ExitBlock();
	}

	namespace {

	/// Representation of the context node suitable for yaml serialization /
	/// deserialization.
	using SerializableFlatProfileRepresentation =
	std::pair<ctx_profile::GUID, std::vector<uint64_t>>;

	struct SerializableCtxRepresentation {
	ctx_profile::GUID Guid = 0;
	std::vector<uint64_t> Counters;
	std::vector<std::vector<SerializableCtxRepresentation>> Callsites;
	};

	struct SerializableRootRepresentation : public SerializableCtxRepresentation {
	uint64_t TotalRootEntryCount = 0;
	std::vector<SerializableFlatProfileRepresentation> Unhandled;
	};

	struct SerializableProfileRepresentation {
	std::vector<SerializableRootRepresentation> Contexts;
	std::vector<SerializableFlatProfileRepresentation> FlatProfiles;
	};

	ctx_profile::ContextNode *
	createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
	const std::vector<SerializableCtxRepresentation> &DCList);

	// Convert a DeserializableCtx into a ContextNode, potentially linking it to
	// its sibling (e.g. callee at same callsite) "Next".
	ctx_profile::ContextNode *
	createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
	const SerializableCtxRepresentation &DC,
	ctx_profile::ContextNode *Next = nullptr) {
	auto AllocSize = ctx_profile::ContextNode::getAllocSize(DC.Counters.size(),
	DC.Callsites.size());
	auto *Mem = Nodes.emplace_back(std::make_unique<char[]>(AllocSize)).get();
	std::memset(Mem, 0, AllocSize);
	auto *Ret = new (Mem) ctx_profile::ContextNode(DC.Guid, DC.Counters.size(),
	DC.Callsites.size(), Next);
	std::memcpy(Ret->counters(), DC.Counters.data(),
	sizeof(uint64_t) * DC.Counters.size());
	for (const auto &[I, DCList] : llvm::enumerate(DC.Callsites))
	Ret->subContexts()[I] = createNode(Nodes, DCList);
	return Ret;
	}

	// Convert a list of SerializableCtxRepresentation into a linked list of
	// ContextNodes.
	ctx_profile::ContextNode *
	createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
	const std::vector<SerializableCtxRepresentation> &DCList) {
	ctx_profile::ContextNode *List = nullptr;
	for (const auto &DC : DCList)
	List = createNode(Nodes, DC, List);
	return List;
	}
	} // namespace

	LLVM_YAML_IS_SEQUENCE_VECTOR(SerializableCtxRepresentation)
	LLVM_YAML_IS_SEQUENCE_VECTOR(std::vector<SerializableCtxRepresentation>)
	LLVM_YAML_IS_SEQUENCE_VECTOR(SerializableRootRepresentation)
	LLVM_YAML_IS_SEQUENCE_VECTOR(SerializableFlatProfileRepresentation)
	template <> struct yaml::MappingTraits<SerializableCtxRepresentation> {
	static void mapping(yaml::IO &IO, SerializableCtxRepresentation &SCR) {
	IO.mapRequired("Guid", SCR.Guid);
	IO.mapRequired("Counters", SCR.Counters);
	IO.mapOptional("Callsites", SCR.Callsites);
	}
	};

	template <> struct yaml::MappingTraits<SerializableRootRepresentation> {
	static void mapping(yaml::IO &IO, SerializableRootRepresentation &R) {
	yaml::MappingTraits<SerializableCtxRepresentation>::mapping(IO, R);
	IO.mapRequired("TotalRootEntryCount", R.TotalRootEntryCount);
	IO.mapOptional("Unhandled", R.Unhandled);
	}
	};

	template <> struct yaml::MappingTraits<SerializableProfileRepresentation> {
	static void mapping(yaml::IO &IO, SerializableProfileRepresentation &SPR) {
	IO.mapOptional("Contexts", SPR.Contexts);
	IO.mapOptional("FlatProfiles", SPR.FlatProfiles);
	}
	};

	template <> struct yaml::MappingTraits<SerializableFlatProfileRepresentation> {
	static void mapping(yaml::IO &IO,
	SerializableFlatProfileRepresentation &SFPR) {
	IO.mapRequired("Guid", SFPR.first);
	IO.mapRequired("Counters", SFPR.second);
	}
	};

	Error llvm::createCtxProfFromYAML(StringRef Profile, raw_ostream &Out) {
	yaml::Input In(Profile);
	SerializableProfileRepresentation SPR;
	In >> SPR;
	if (In.error())
	return createStringError(In.error(), "incorrect yaml content");
	std::vector<std::unique_ptr<char[]>> Nodes;
	std::error_code EC;
	if (EC)
	return createStringError(EC, "failed to open output");
	PGOCtxProfileWriter Writer(Out);

	if (!SPR.Contexts.empty()) {
	Writer.startContextSection();
	for (const auto &DC : SPR.Contexts) {
	auto *TopList = createNode(Nodes, DC);
	if (!TopList)
	return createStringError(
	"Unexpected error converting internal structure to ctx profile");

	ctx_profile::ContextNode *FirstUnhandled = nullptr;
	for (const auto &U : DC.Unhandled) {
	SerializableCtxRepresentation Unhandled;
	Unhandled.Guid = U.first;
	Unhandled.Counters = U.second;
	FirstUnhandled = createNode(Nodes, Unhandled, FirstUnhandled);
	}
	Writer.writeContextual(*TopList, FirstUnhandled, DC.TotalRootEntryCount);
	}
	Writer.endContextSection();
	}
	if (!SPR.FlatProfiles.empty()) {
	Writer.startFlatSection();
	for (const auto &[Guid, Counters] : SPR.FlatProfiles)
	Writer.writeFlat(Guid, Counters.data(), Counters.size());
	Writer.endFlatSection();
	}
	if (EC)
	return createStringError(EC, "failed to write output");
	return Error::success();
	}