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//===- 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/JSON.h"
using namespace llvm;
using namespace llvm::ctx_profile;
PGOCtxProfileWriter::PGOCtxProfileWriter(
raw_ostream &Out, std::optional<unsigned> VersionOverride)
: Writer(Out, 0) {
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::ContextNodeBlockID, "Context");
DescribeRecord(PGOCtxProfileRecords::Guid, "GUID");
DescribeRecord(PGOCtxProfileRecords::CalleeIndex, "CalleeIndex");
DescribeRecord(PGOCtxProfileRecords::Counters, "Counters");
}
Writer.ExitBlock();
Writer.EnterSubblock(PGOCtxProfileBlockIDs::ProfileMetadataBlockID, CodeLen);
const auto Version = VersionOverride ? *VersionOverride : CurrentVersion;
Writer.EmitRecord(PGOCtxProfileRecords::Version,
SmallVector<unsigned, 1>({Version}));
}
void PGOCtxProfileWriter::writeCounters(const ContextNode &Node) {
Writer.EmitCode(bitc::UNABBREV_RECORD);
Writer.EmitVBR(PGOCtxProfileRecords::Counters, VBREncodingBits);
Writer.EmitVBR(Node.counters_size(), VBREncodingBits);
for (uint32_t I = 0U; I < Node.counters_size(); ++I)
Writer.EmitVBR64(Node.counters()[I], VBREncodingBits);
}
// 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::writeImpl(std::optional<uint32_t> CallerIndex,
const ContextNode &Node) {
Writer.EnterSubblock(PGOCtxProfileBlockIDs::ContextNodeBlockID, CodeLen);
Writer.EmitRecord(PGOCtxProfileRecords::Guid,
SmallVector<uint64_t, 1>{Node.guid()});
if (CallerIndex)
Writer.EmitRecord(PGOCtxProfileRecords::CalleeIndex,
SmallVector<uint64_t, 1>{*CallerIndex});
writeCounters(Node);
for (uint32_t I = 0U; I < Node.callsites_size(); ++I)
for (const auto *Subcontext = Node.subContexts()[I]; Subcontext;
Subcontext = Subcontext->next())
writeImpl(I, *Subcontext);
Writer.ExitBlock();
}
void PGOCtxProfileWriter::write(const ContextNode &RootNode) {
writeImpl(std::nullopt, RootNode);
}
namespace {
// A structural representation of the JSON input.
struct DeserializableCtx {
ctx_profile::GUID Guid = 0;
std::vector<uint64_t> Counters;
std::vector<std::vector<DeserializableCtx>> Callsites;
};
ctx_profile::ContextNode *
createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
const std::vector<DeserializableCtx> &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 DeserializableCtx &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 DeserializableCtx into a linked list of ContextNodes.
ctx_profile::ContextNode *
createNode(std::vector<std::unique_ptr<char[]>> &Nodes,
const std::vector<DeserializableCtx> &DCList) {
ctx_profile::ContextNode *List = nullptr;
for (const auto &DC : DCList)
List = createNode(Nodes, DC, List);
return List;
}
} // namespace
namespace llvm {
namespace json {
bool fromJSON(const Value &E, DeserializableCtx &R, Path P) {
json::ObjectMapper Mapper(E, P);
return Mapper && Mapper.map("Guid", R.Guid) &&
Mapper.map("Counters", R.Counters) &&
Mapper.mapOptional("Callsites", R.Callsites);
}
} // namespace json
} // namespace llvm
Error llvm::createCtxProfFromJSON(StringRef Profile, raw_ostream &Out) {
auto P = json::parse(Profile);
if (!P)
return P.takeError();
json::Path::Root R("");
std::vector<DeserializableCtx> DCList;
if (!fromJSON(*P, DCList, R))
return R.getError();
// Nodes provides memory backing for the ContextualNodes.
std::vector<std::unique_ptr<char[]>> Nodes;
std::error_code EC;
if (EC)
return createStringError(EC, "failed to open output");
PGOCtxProfileWriter Writer(Out);
for (const auto &DC : DCList) {
auto *TopList = createNode(Nodes, DC);
if (!TopList)
return createStringError(
"Unexpected error converting internal structure to ctx profile");
Writer.write(*TopList);
}
if (EC)
return createStringError(EC, "failed to write output");
return Error::success();
}
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