Non-debuginfo JITLink perf jitdump support

This patch ports PerfJITEventListener to a JITLink plugin, but adds unwind record support and drops debuginfo support temporarily. Debuginfo can be enabled in the future by providing a way to obtain a DWARFContext from a LinkGraph.

See D146060 for an experimental implementation that adds debuginfo parsing.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D146169

4 files changed, 784 insertions, 0 deletions

diff --git a/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt b/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt
index 1055e31..55e31b3 100644
--- a/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt
+++ b/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt
@@ -41,6 +41,7 @@ add_llvm_component_library(LLVMOrcJIT
   ObjectTransformLayer.cpp
   OrcABISupport.cpp
   OrcV2CBindings.cpp
+  PerfSupportPlugin.cpp
   RTDyldObjectLinkingLayer.cpp
   SimpleRemoteEPC.cpp
   Speculation.cpp
diff --git a/llvm/lib/ExecutionEngine/Orc/PerfSupportPlugin.cpp b/llvm/lib/ExecutionEngine/Orc/PerfSupportPlugin.cpp
new file mode 100644
index 0000000..bcb445e
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/PerfSupportPlugin.cpp
@@ -0,0 +1,317 @@
+//===----- PerfSupportPlugin.cpp --- Utils for perf support -----*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Handles support for registering code with perf
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/PerfSupportPlugin.h"
+
+#include "llvm/ExecutionEngine/Orc/Shared/WrapperFunctionUtils.h"
+
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+#include "llvm/ExecutionEngine/JITLink/x86_64.h"
+#include "llvm/ExecutionEngine/Orc/LookupAndRecordAddrs.h"
+
+#define DEBUG_TYPE "orc"
+
+using namespace llvm;
+using namespace llvm::orc;
+using namespace llvm::jitlink;
+
+namespace {
+
+// Creates an EH frame header prepared for a 32-bit relative relocation
+// to the start of the .eh_frame section. Absolute injects a 64-bit absolute
+// address space offset 4 bytes from the start instead of 4 bytes
+Expected<std::string> createX64EHFrameHeader(Section &EHFrame,
+                                             support::endianness endianness,
+                                             bool absolute) {
+  uint8_t Version = 1;
+  uint8_t EhFramePtrEnc = 0;
+  if (absolute) {
+    EhFramePtrEnc |= dwarf::DW_EH_PE_sdata8 | dwarf::DW_EH_PE_absptr;
+  } else {
+    EhFramePtrEnc |= dwarf::DW_EH_PE_sdata4 | dwarf::DW_EH_PE_datarel;
+  }
+  uint8_t FDECountEnc = dwarf::DW_EH_PE_omit;
+  uint8_t TableEnc = dwarf::DW_EH_PE_omit;
+  // X86_64_64 relocation to the start of the .eh_frame section
+  uint32_t EHFrameRelocation = 0;
+  // uint32_t FDECount = 0;
+  // Skip the FDE binary search table
+  // We'd have to reprocess the CIEs to get this information,
+  // which seems like more trouble than it's worth
+  // TODO consider implementing this.
+  // binary search table goes here
+
+  size_t HeaderSize =
+      (sizeof(Version) + sizeof(EhFramePtrEnc) + sizeof(FDECountEnc) +
+       sizeof(TableEnc) +
+       (absolute ? sizeof(uint64_t) : sizeof(EHFrameRelocation)));
+  std::string HeaderContent(HeaderSize, '\0');
+  BinaryStreamWriter Writer(
+      MutableArrayRef<uint8_t>(
+          reinterpret_cast<uint8_t *>(HeaderContent.data()), HeaderSize),
+      endianness);
+  if (auto Err = Writer.writeInteger(Version))
+    return std::move(Err);
+  if (auto Err = Writer.writeInteger(EhFramePtrEnc))
+    return std::move(Err);
+  if (auto Err = Writer.writeInteger(FDECountEnc))
+    return std::move(Err);
+  if (auto Err = Writer.writeInteger(TableEnc))
+    return std::move(Err);
+  if (absolute) {
+    uint64_t EHFrameAddr = SectionRange(EHFrame).getStart().getValue();
+    if (auto Err = Writer.writeInteger(EHFrameAddr))
+      return std::move(Err);
+  } else {
+    if (auto Err = Writer.writeInteger(EHFrameRelocation))
+      return std::move(Err);
+  }
+  return HeaderContent;
+}
+
+constexpr StringRef RegisterPerfStartSymbolName =
+    "llvm_orc_registerJITLoaderPerfStart";
+constexpr StringRef RegisterPerfEndSymbolName =
+    "llvm_orc_registerJITLoaderPerfEnd";
+constexpr StringRef RegisterPerfImplSymbolName =
+    "llvm_orc_registerJITLoaderPerfImpl";
+
+static inline uint64_t timespec_to_ns(const struct timespec *ts) {
+  const uint64_t NanoSecPerSec = 1000000000;
+  return ((uint64_t)ts->tv_sec * NanoSecPerSec) + ts->tv_nsec;
+}
+
+static inline uint64_t perf_get_timestamp() {
+#ifdef __linux__
+  struct timespec ts;
+  int ret;
+
+  ret = clock_gettime(CLOCK_MONOTONIC, &ts);
+  if (ret)
+    return 0;
+
+  return timespec_to_ns(&ts);
+#else
+  return 0;
+#endif
+}
+
+static PerfJITCodeLoadRecord
+getCodeLoadRecord(const Symbol &Sym, std::atomic<uint64_t> &CodeIndex) {
+  PerfJITCodeLoadRecord Record;
+  auto Name = Sym.getName();
+  auto Addr = Sym.getAddress();
+  auto Size = Sym.getSize();
+  Record.Prefix.Id = PerfJITRecordType::JIT_CODE_LOAD;
+  // Runtime sets PID
+  Record.Pid = 0;
+  // Runtime sets TID
+  Record.Tid = 0;
+  Record.Vma = Addr.getValue();
+  Record.CodeAddr = Addr.getValue();
+  Record.CodeSize = Size;
+  Record.CodeIndex = CodeIndex++;
+  Record.Name = Name.str();
+  // Initialize last, once all the other fields are filled
+  Record.Prefix.TotalSize =
+      (2 * sizeof(uint32_t)   // id, total_size
+       + sizeof(uint64_t)     // timestamp
+       + 2 * sizeof(uint32_t) // pid, tid
+       + 4 * sizeof(uint64_t) // vma, code_addr, code_size, code_index
+       + Name.size() + 1      // symbol name
+       + Record.CodeSize      // code
+      );
+  return Record;
+}
+
+static std::optional<PerfJITDebugInfoRecord>
+getDebugInfoRecord(const Symbol &Sym, DWARFContext *DC) {
+  if (!DC) {
+    LLVM_DEBUG(dbgs() << "No debug info available\n");
+    return std::nullopt;
+  }
+  auto &Section = Sym.getBlock().getSection();
+  auto Addr = Sym.getAddress();
+  auto Size = Sym.getSize();
+  auto SAddr = object::SectionedAddress{Addr.getValue(), Section.getOrdinal()};
+  LLVM_DEBUG(dbgs() << "Getting debug info for symbol " << Sym.getName()
+                    << " at address " << Addr.getValue() << " with size "
+                    << Size << "\n"
+                    << "Section ordinal: " << Section.getOrdinal() << "\n");
+  auto LInfo = DC->getLineInfoForAddressRange(
+      SAddr, Size, DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath);
+  if (LInfo.empty()) {
+    // No line info available
+    LLVM_DEBUG(dbgs() << "No line info available\n");
+    return std::nullopt;
+  }
+  PerfJITDebugInfoRecord Record;
+  Record.Prefix.Id = PerfJITRecordType::JIT_CODE_DEBUG_INFO;
+  Record.CodeAddr = Addr.getValue();
+  for (const auto &Entry : LInfo) {
+    auto Addr = Entry.first;
+    // The function re-created by perf is preceded by a elf
+    // header. Need to adjust for that, otherwise the results are
+    // wrong.
+    Addr += 0x40;
+    Record.Entries.push_back({Addr, Entry.second.Line,
+                              Entry.second.Discriminator,
+                              Entry.second.FileName});
+  }
+  size_t EntriesBytes = (2   // record header
+                         + 2 // record fields
+                         ) *
+                        sizeof(uint64_t);
+  for (const auto &Entry : Record.Entries) {
+    EntriesBytes +=
+        sizeof(uint64_t) + 2 * sizeof(uint32_t); // Addr, Line/Discrim
+    EntriesBytes += Entry.Name.size() + 1;       // Name
+  }
+  Record.Prefix.TotalSize = EntriesBytes;
+  LLVM_DEBUG(dbgs() << "Created debug info record\n"
+                    << "Total size: " << Record.Prefix.TotalSize << "\n"
+                    << "Nr entries: " << Record.Entries.size() << "\n");
+  return Record;
+}
+
+static Expected<PerfJITCodeUnwindingInfoRecord>
+getUnwindingRecord(LinkGraph &G) {
+  PerfJITCodeUnwindingInfoRecord Record;
+  Record.Prefix.Id = PerfJITRecordType::JIT_CODE_UNWINDING_INFO;
+  Record.Prefix.TotalSize = 0;
+  auto Eh_frame = G.findSectionByName(".eh_frame");
+  if (!Eh_frame) {
+    LLVM_DEBUG(dbgs() << "No .eh_frame section found\n");
+    return Record;
+  }
+  if (!G.getTargetTriple().isOSBinFormatELF()) {
+    LLVM_DEBUG(dbgs() << "Not an ELF file, will not emit unwinding info\n");
+    return Record;
+  }
+  auto SR = SectionRange(*Eh_frame);
+  auto EHFrameSize = SR.getSize();
+  auto Eh_frame_hdr = G.findSectionByName(".eh_frame_hdr");
+  if (!Eh_frame_hdr) {
+    if (G.getTargetTriple().getArch() == Triple::x86_64) {
+      auto Hdr = createX64EHFrameHeader(*Eh_frame, G.getEndianness(), true);
+      if (!Hdr)
+        return Hdr.takeError();
+      Record.EHFrameHdr = std::move(*Hdr);
+    } else {
+      LLVM_DEBUG(dbgs() << "No .eh_frame_hdr section found\n");
+      return Record;
+    }
+    Record.EHFrameHdrAddr = 0;
+    Record.EHFrameHdrSize = Record.EHFrameHdr.size();
+    Record.UnwindDataSize = EHFrameSize + Record.EHFrameHdrSize;
+    Record.MappedSize = 0; // Because the EHFrame header was not mapped
+  } else {
+    auto SR = SectionRange(*Eh_frame_hdr);
+    Record.EHFrameHdrAddr = SR.getStart().getValue();
+    Record.EHFrameHdrSize = SR.getSize();
+    Record.UnwindDataSize = EHFrameSize + Record.EHFrameHdrSize;
+    Record.MappedSize = Record.UnwindDataSize;
+  }
+  Record.EHFrameAddr = SR.getStart().getValue();
+  Record.Prefix.TotalSize =
+      (2 * sizeof(uint32_t) // id, total_size
+       + sizeof(uint64_t)   // timestamp
+       +
+       3 * sizeof(uint64_t) // unwind_data_size, eh_frame_hdr_size, mapped_size
+       + Record.UnwindDataSize // eh_frame_hdr, eh_frame
+      );
+  LLVM_DEBUG(dbgs() << "Created unwind record\n"
+                    << "Total size: " << Record.Prefix.TotalSize << "\n"
+                    << "Unwind size: " << Record.UnwindDataSize << "\n"
+                    << "EHFrame size: " << EHFrameSize << "\n"
+                    << "EHFrameHdr size: " << Record.EHFrameHdrSize << "\n");
+  return Record;
+}
+
+static PerfJITRecordBatch getRecords(ExecutionSession &ES, LinkGraph &G,
+                                     DWARFContext *DC,
+                                     std::atomic<uint64_t> &CodeIndex,
+                                     bool EmitUnwindInfo) {
+  PerfJITRecordBatch Batch;
+  for (auto Sym : G.defined_symbols()) {
+    if (!Sym->hasName() || !Sym->isCallable())
+      continue;
+    auto DebugInfo = getDebugInfoRecord(*Sym, DC);
+    if (DebugInfo)
+      Batch.DebugInfoRecords.push_back(std::move(*DebugInfo));
+    Batch.CodeLoadRecords.push_back(getCodeLoadRecord(*Sym, CodeIndex));
+  }
+  if (EmitUnwindInfo) {
+    auto UWR = getUnwindingRecord(G);
+    if (!UWR) {
+      ES.reportError(UWR.takeError());
+    } else {
+      Batch.UnwindingRecord = std::move(*UWR);
+    }
+  } else {
+    Batch.UnwindingRecord.Prefix.TotalSize = 0;
+  }
+  return Batch;
+}
+} // namespace
+
+PerfSupportPlugin::PerfSupportPlugin(ExecutorProcessControl &EPC,
+                                     ExecutorAddr RegisterPerfStartAddr,
+                                     ExecutorAddr RegisterPerfEndAddr,
+                                     ExecutorAddr RegisterPerfImplAddr,
+                                     bool EmitUnwindInfo)
+    : EPC(EPC), RegisterPerfStartAddr(RegisterPerfStartAddr),
+      RegisterPerfEndAddr(RegisterPerfEndAddr),
+      RegisterPerfImplAddr(RegisterPerfImplAddr), CodeIndex(0),
+      EmitUnwindInfo(EmitUnwindInfo) {
+  cantFail(EPC.callSPSWrapper<void()>(RegisterPerfStartAddr));
+}
+PerfSupportPlugin::~PerfSupportPlugin() {
+  cantFail(EPC.callSPSWrapper<void()>(RegisterPerfEndAddr));
+}
+
+void PerfSupportPlugin::modifyPassConfig(MaterializationResponsibility &MR,
+                                         LinkGraph &G,
+                                         PassConfiguration &Config) {
+  Config.PostFixupPasses.push_back([this, &MR](LinkGraph &G) {
+    // TODO get an actual DWARFContext for line info
+    DWARFContext *DWC = nullptr;
+    auto Batch = getRecords(EPC.getExecutionSession(), G, DWC, CodeIndex,
+                            EmitUnwindInfo);
+    G.allocActions().push_back(
+        {cantFail(shared::WrapperFunctionCall::Create<
+                  shared::SPSArgList<shared::SPSPerfJITRecordBatch>>(
+             RegisterPerfImplAddr, Batch)),
+         {}});
+    return Error::success();
+  });
+}
+
+Expected<std::unique_ptr<PerfSupportPlugin>>
+PerfSupportPlugin::Create(ExecutorProcessControl &EPC, JITDylib &JD,
+                          bool EmitUnwindInfo) {
+  if (!EPC.getTargetTriple().isOSBinFormatELF()) {
+    return make_error<StringError>(
+        "Perf support only available for ELF LinkGraphs!",
+        inconvertibleErrorCode());
+  }
+  auto &ES = EPC.getExecutionSession();
+  ExecutorAddr StartAddr, EndAddr, ImplAddr;
+  if (auto Err = lookupAndRecordAddrs(
+          ES, LookupKind::Static, makeJITDylibSearchOrder({&JD}),
+          {{ES.intern(RegisterPerfStartSymbolName), &StartAddr},
+           {ES.intern(RegisterPerfEndSymbolName), &EndAddr},
+           {ES.intern(RegisterPerfImplSymbolName), &ImplAddr}}))
+    return std::move(Err);
+  return std::make_unique<PerfSupportPlugin>(EPC, StartAddr, EndAddr, ImplAddr,
+                                             EmitUnwindInfo);
+}
diff --git a/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt b/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt
index d9cd7b6..f2005dc 100644
--- a/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt
+++ b/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt
@@ -5,6 +5,7 @@ endif()
 add_llvm_component_library(LLVMOrcTargetProcess
   ExecutorSharedMemoryMapperService.cpp
   JITLoaderGDB.cpp
+  JITLoaderPerf.cpp
   OrcRTBootstrap.cpp
   RegisterEHFrames.cpp
   SimpleExecutorDylibManager.cpp
diff --git a/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderPerf.cpp b/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderPerf.cpp
new file mode 100644
index 0000000..cf0d29c
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/TargetProcess/JITLoaderPerf.cpp
@@ -0,0 +1,465 @@
+//===------- JITLoaderPerf.cpp - Register profiler objects ------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Register objects for access by profilers via the perf JIT interface.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/TargetProcess/JITLoaderPerf.h"
+
+#include "llvm/ExecutionEngine/Orc/Shared/PerfSharedStructs.h"
+
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include "llvm/Support/Path.h"
+#include "llvm/Support/Process.h"
+#include "llvm/Support/Threading.h"
+
+#include <mutex>
+#include <optional>
+
+#ifdef __linux__
+
+#include <sys/mman.h> // mmap()
+#include <time.h>     // clock_gettime(), time(), localtime_r() */
+#include <unistd.h>   // for read(), close()
+
+#define DEBUG_TYPE "orc"
+
+// language identifier (XXX: should we generate something better from debug
+// info?)
+#define JIT_LANG "llvm-IR"
+#define LLVM_PERF_JIT_MAGIC                                                    \
+  ((uint32_t)'J' << 24 | (uint32_t)'i' << 16 | (uint32_t)'T' << 8 |            \
+   (uint32_t)'D')
+#define LLVM_PERF_JIT_VERSION 1
+
+using namespace llvm;
+using namespace llvm::orc;
+
+struct PerfState {
+  // cache lookups
+  uint32_t Pid;
+
+  // base directory for output data
+  std::string JitPath;
+
+  // output data stream, closed via Dumpstream
+  int DumpFd = -1;
+
+  // output data stream
+  std::unique_ptr<raw_fd_ostream> Dumpstream;
+
+  // perf mmap marker
+  void *MarkerAddr = NULL;
+};
+
+// prevent concurrent dumps from messing up the output file
+static std::mutex Mutex;
+static std::optional<PerfState> state;
+
+struct RecHeader {
+  uint32_t Id;
+  uint32_t TotalSize;
+  uint64_t Timestamp;
+};
+
+struct DIR {
+  RecHeader Prefix;
+  uint64_t CodeAddr;
+  uint64_t NrEntry;
+};
+
+struct DIE {
+  uint64_t CodeAddr;
+  uint32_t Line;
+  uint32_t Discrim;
+};
+
+struct CLR {
+  RecHeader Prefix;
+  uint32_t Pid;
+  uint32_t Tid;
+  uint64_t Vma;
+  uint64_t CodeAddr;
+  uint64_t CodeSize;
+  uint64_t CodeIndex;
+};
+
+struct UWR {
+  RecHeader Prefix;
+  uint64_t UnwindDataSize;
+  uint64_t EhFrameHeaderSize;
+  uint64_t MappedSize;
+};
+
+static inline uint64_t timespec_to_ns(const struct timespec *ts) {
+  const uint64_t NanoSecPerSec = 1000000000;
+  return ((uint64_t)ts->tv_sec * NanoSecPerSec) + ts->tv_nsec;
+}
+
+static inline uint64_t perf_get_timestamp() {
+  struct timespec ts;
+  int ret;
+
+  ret = clock_gettime(CLOCK_MONOTONIC, &ts);
+  if (ret)
+    return 0;
+
+  return timespec_to_ns(&ts);
+}
+
+static void writeDebugRecord(const PerfJITDebugInfoRecord &DebugRecord) {
+  assert(state && "PerfState not initialized");
+  LLVM_DEBUG(dbgs() << "Writing debug record with "
+                    << DebugRecord.Entries.size() << " entries\n");
+  size_t Written = 0;
+  DIR dir{RecHeader{static_cast<uint32_t>(DebugRecord.Prefix.Id),
+                    DebugRecord.Prefix.TotalSize, perf_get_timestamp()},
+          DebugRecord.CodeAddr, DebugRecord.Entries.size()};
+  state->Dumpstream->write(reinterpret_cast<const char *>(&dir), sizeof(dir));
+  Written += sizeof(dir);
+  for (auto &die : DebugRecord.Entries) {
+    DIE d{die.Addr, die.Lineno, die.Discrim};
+    state->Dumpstream->write(reinterpret_cast<const char *>(&d), sizeof(d));
+    state->Dumpstream->write(die.Name.data(), die.Name.size() + 1);
+    Written += sizeof(d) + die.Name.size() + 1;
+  }
+  LLVM_DEBUG(dbgs() << "wrote " << Written << " bytes of debug info\n");
+}
+
+static void writeCodeRecord(const PerfJITCodeLoadRecord &CodeRecord) {
+  assert(state && "PerfState not initialized");
+  uint32_t Tid = get_threadid();
+  LLVM_DEBUG(dbgs() << "Writing code record with code size "
+                    << CodeRecord.CodeSize << " and code index "
+                    << CodeRecord.CodeIndex << "\n");
+  CLR clr{RecHeader{static_cast<uint32_t>(CodeRecord.Prefix.Id),
+                    CodeRecord.Prefix.TotalSize, perf_get_timestamp()},
+          state->Pid,
+          Tid,
+          CodeRecord.Vma,
+          CodeRecord.CodeAddr,
+          CodeRecord.CodeSize,
+          CodeRecord.CodeIndex};
+  LLVM_DEBUG(dbgs() << "wrote " << sizeof(clr) << " bytes of CLR, "
+                    << CodeRecord.Name.size() + 1 << " bytes of name, "
+                    << CodeRecord.CodeSize << " bytes of code\n");
+  state->Dumpstream->write(reinterpret_cast<const char *>(&clr), sizeof(clr));
+  state->Dumpstream->write(CodeRecord.Name.data(), CodeRecord.Name.size() + 1);
+  state->Dumpstream->write((const char *)CodeRecord.CodeAddr,
+                           CodeRecord.CodeSize);
+}
+
+static void
+writeUnwindRecord(const PerfJITCodeUnwindingInfoRecord &UnwindRecord) {
+  assert(state && "PerfState not initialized");
+  dbgs() << "Writing unwind record with unwind data size "
+         << UnwindRecord.UnwindDataSize << " and EH frame header size "
+         << UnwindRecord.EHFrameHdrSize << " and mapped size "
+         << UnwindRecord.MappedSize << "\n";
+  UWR uwr{RecHeader{static_cast<uint32_t>(UnwindRecord.Prefix.Id),
+                    UnwindRecord.Prefix.TotalSize, perf_get_timestamp()},
+          UnwindRecord.UnwindDataSize, UnwindRecord.EHFrameHdrSize,
+          UnwindRecord.MappedSize};
+  LLVM_DEBUG(dbgs() << "wrote " << sizeof(uwr) << " bytes of UWR, "
+                    << UnwindRecord.EHFrameHdrSize
+                    << " bytes of EH frame header, "
+                    << UnwindRecord.UnwindDataSize - UnwindRecord.EHFrameHdrSize
+                    << " bytes of EH frame\n");
+  state->Dumpstream->write(reinterpret_cast<const char *>(&uwr), sizeof(uwr));
+  if (UnwindRecord.EHFrameHdrAddr) {
+    state->Dumpstream->write((const char *)UnwindRecord.EHFrameHdrAddr,
+                             UnwindRecord.EHFrameHdrSize);
+  } else {
+    state->Dumpstream->write(UnwindRecord.EHFrameHdr.data(),
+                             UnwindRecord.EHFrameHdrSize);
+  }
+  state->Dumpstream->write((const char *)UnwindRecord.EHFrameAddr,
+                           UnwindRecord.UnwindDataSize -
+                               UnwindRecord.EHFrameHdrSize);
+}
+
+static Error registerJITLoaderPerfImpl(const PerfJITRecordBatch &Batch) {
+  if (!state) {
+    return make_error<StringError>("PerfState not initialized",
+                                   inconvertibleErrorCode());
+  }
+
+  // Serialize the batch
+  std::lock_guard<std::mutex> Lock(Mutex);
+  if (Batch.UnwindingRecord.Prefix.TotalSize > 0) {
+    writeUnwindRecord(Batch.UnwindingRecord);
+  }
+  for (const auto &DebugInfo : Batch.DebugInfoRecords) {
+    writeDebugRecord(DebugInfo);
+  }
+  for (const auto &CodeLoad : Batch.CodeLoadRecords) {
+    writeCodeRecord(CodeLoad);
+  }
+
+  state->Dumpstream->flush();
+
+  return Error::success();
+}
+
+struct Header {
+  uint32_t Magic;     // characters "JiTD"
+  uint32_t Version;   // header version
+  uint32_t TotalSize; // total size of header
+  uint32_t ElfMach;   // elf mach target
+  uint32_t Pad1;      // reserved
+  uint32_t Pid;
+  uint64_t Timestamp; // timestamp
+  uint64_t Flags;     // flags
+};
+
+static Error OpenMarker(PerfState &state) {
+  // We mmap the jitdump to create an MMAP RECORD in perf.data file.  The mmap
+  // is captured either live (perf record running when we mmap) or in deferred
+  // mode, via /proc/PID/maps. The MMAP record is used as a marker of a jitdump
+  // file for more meta data info about the jitted code. Perf report/annotate
+  // detect this special filename and process the jitdump file.
+  //
+  // Mapping must be PROT_EXEC to ensure it is captured by perf record
+  // even when not using -d option.
+  state.MarkerAddr =
+      ::mmap(NULL, sys::Process::getPageSizeEstimate(), PROT_READ | PROT_EXEC,
+             MAP_PRIVATE, state.DumpFd, 0);
+
+  if (state.MarkerAddr == MAP_FAILED) {
+    return make_error<llvm::StringError>("could not mmap JIT marker",
+                                         inconvertibleErrorCode());
+  }
+  return Error::success();
+}
+
+void CloseMarker(PerfState &state) {
+  if (!state.MarkerAddr)
+    return;
+
+  munmap(state.MarkerAddr, sys::Process::getPageSizeEstimate());
+  state.MarkerAddr = nullptr;
+}
+
+static Expected<Header> FillMachine(PerfState &state) {
+  Header hdr;
+  hdr.Magic = LLVM_PERF_JIT_MAGIC;
+  hdr.Version = LLVM_PERF_JIT_VERSION;
+  hdr.TotalSize = sizeof(hdr);
+  hdr.Pid = state.Pid;
+  hdr.Timestamp = perf_get_timestamp();
+
+  char id[16];
+  struct {
+    uint16_t e_type;
+    uint16_t e_machine;
+  } info;
+
+  size_t RequiredMemory = sizeof(id) + sizeof(info);
+
+  ErrorOr<std::unique_ptr<MemoryBuffer>> MB =
+      MemoryBuffer::getFileSlice("/proc/self/exe", RequiredMemory, 0);
+
+  // This'll not guarantee that enough data was actually read from the
+  // underlying file. Instead the trailing part of the buffer would be
+  // zeroed. Given the ELF signature check below that seems ok though,
+  // it's unlikely that the file ends just after that, and the
+  // consequence would just be that perf wouldn't recognize the
+  // signature.
+  if (!MB) {
+    return make_error<llvm::StringError>("could not open /proc/self/exe",
+                                         MB.getError());
+  }
+
+  memcpy(&id, (*MB)->getBufferStart(), sizeof(id));
+  memcpy(&info, (*MB)->getBufferStart() + sizeof(id), sizeof(info));
+
+  // check ELF signature
+  if (id[0] != 0x7f || id[1] != 'E' || id[2] != 'L' || id[3] != 'F') {
+    return make_error<llvm::StringError>("invalid ELF signature",
+                                         inconvertibleErrorCode());
+  }
+
+  hdr.ElfMach = info.e_machine;
+
+  return hdr;
+}
+
+static Error InitDebuggingDir(PerfState &state) {
+  time_t Time;
+  struct tm LocalTime;
+  char TimeBuffer[sizeof("YYYYMMDD")];
+  SmallString<64> Path;
+
+  // search for location to dump data to
+  if (const char *BaseDir = getenv("JITDUMPDIR"))
+    Path.append(BaseDir);
+  else if (!sys::path::home_directory(Path))
+    Path = ".";
+
+  // create debug directory
+  Path += "/.debug/jit/";
+  if (auto EC = sys::fs::create_directories(Path)) {
+    std::string errstr;
+    raw_string_ostream errstream(errstr);
+    errstream << "could not create jit cache directory " << Path << ": "
+              << EC.message() << "\n";
+    return make_error<StringError>(std::move(errstr), inconvertibleErrorCode());
+  }
+
+  // create unique directory for dump data related to this process
+  time(&Time);
+  localtime_r(&Time, &LocalTime);
+  strftime(TimeBuffer, sizeof(TimeBuffer), "%Y%m%d", &LocalTime);
+  Path += JIT_LANG "-jit-";
+  Path += TimeBuffer;
+
+  SmallString<128> UniqueDebugDir;
+
+  using sys::fs::createUniqueDirectory;
+  if (auto EC = createUniqueDirectory(Path, UniqueDebugDir)) {
+    std::string errstr;
+    raw_string_ostream errstream(errstr);
+    errstream << "could not create unique jit cache directory "
+              << UniqueDebugDir << ": " << EC.message() << "\n";
+    return make_error<StringError>(std::move(errstr), inconvertibleErrorCode());
+  }
+
+  state.JitPath = std::string(UniqueDebugDir.str());
+
+  return Error::success();
+}
+
+static Error registerJITLoaderPerfStartImpl() {
+  PerfState tentative;
+  tentative.Pid = sys::Process::getProcessId();
+  // check if clock-source is supported
+  if (!perf_get_timestamp()) {
+    return make_error<StringError>("kernel does not support CLOCK_MONOTONIC",
+                                   inconvertibleErrorCode());
+  }
+
+  if (auto err = InitDebuggingDir(tentative)) {
+    return std::move(err);
+  }
+
+  std::string Filename;
+  raw_string_ostream FilenameBuf(Filename);
+  FilenameBuf << tentative.JitPath << "/jit-" << tentative.Pid << ".dump";
+
+  // Need to open ourselves, because we need to hand the FD to OpenMarker() and
+  // raw_fd_ostream doesn't expose the FD.
+  using sys::fs::openFileForWrite;
+  if (auto EC = openFileForReadWrite(FilenameBuf.str(), tentative.DumpFd,
+                                     sys::fs::CD_CreateNew, sys::fs::OF_None)) {
+    std::string errstr;
+    raw_string_ostream errstream(errstr);
+    errstream << "could not open JIT dump file " << FilenameBuf.str() << ": "
+              << EC.message() << "\n";
+    return make_error<StringError>(std::move(errstr), inconvertibleErrorCode());
+  }
+
+  tentative.Dumpstream =
+      std::make_unique<raw_fd_ostream>(tentative.DumpFd, true);
+
+  auto header = FillMachine(tentative);
+  if (!header) {
+    return header.takeError();
+  }
+
+  // signal this process emits JIT information
+  if (auto err = OpenMarker(tentative)) {
+    return std::move(err);
+  }
+
+  tentative.Dumpstream->write(reinterpret_cast<const char *>(&header.get()),
+                              sizeof(*header));
+
+  // Everything initialized, can do profiling now.
+  if (tentative.Dumpstream->has_error()) {
+    return make_error<StringError>("could not write JIT dump header",
+                                   inconvertibleErrorCode());
+  }
+  state = std::move(tentative);
+  return Error::success();
+}
+
+static Error registerJITLoaderPerfEndImpl() {
+  if (!state) {
+    return make_error<StringError>("PerfState not initialized",
+                                   inconvertibleErrorCode());
+  }
+  RecHeader close;
+  close.Id = static_cast<uint32_t>(PerfJITRecordType::JIT_CODE_CLOSE);
+  close.TotalSize = sizeof(close);
+  close.Timestamp = perf_get_timestamp();
+  state->Dumpstream->write(reinterpret_cast<const char *>(&close),
+                           sizeof(close));
+  if (state->MarkerAddr) {
+    CloseMarker(*state);
+  }
+  state.reset();
+  return Error::success();
+}
+
+extern "C" llvm::orc::shared::CWrapperFunctionResult
+llvm_orc_registerJITLoaderPerfImpl(const char *Data, uint64_t Size) {
+  using namespace orc::shared;
+  return WrapperFunction<SPSError(SPSPerfJITRecordBatch)>::handle(
+             Data, Size, registerJITLoaderPerfImpl)
+      .release();
+}
+
+extern "C" llvm::orc::shared::CWrapperFunctionResult
+llvm_orc_registerJITLoaderPerfStart(const char *Data, uint64_t Size) {
+  using namespace orc::shared;
+  return WrapperFunction<SPSError()>::handle(Data, Size,
+                                             registerJITLoaderPerfStartImpl)
+      .release();
+}
+
+extern "C" llvm::orc::shared::CWrapperFunctionResult
+llvm_orc_registerJITLoaderPerfEnd(const char *Data, uint64_t Size) {
+  using namespace orc::shared;
+  return WrapperFunction<SPSError()>::handle(Data, Size,
+                                             registerJITLoaderPerfEndImpl)
+      .release();
+}
+
+#else
+
+static Error badOS() {
+  return make_error<StringError>(
+      "unsupported OS (perf support is only available on linux!)",
+      inconvertibleErrorCode());
+}
+
+static Error badOSBatch(PerfJITRecordBatch &Batch) { return badOS(); }
+
+extern "C" llvm::orc::shared::CWrapperFunctionResult
+llvm_orc_registerJITLoaderPerfImpl(const char *Data, uint64_t Size) {
+  using namespace orc::shared;
+  return WrapperFunction<SPSError(SPSPerfJITRecordBatch)>::handle(Data, Size,
+                                                                  badOSBatch)
+      .release();
+}
+
+extern "C" llvm::orc::shared::CWrapperFunctionResult
+llvm_orc_registerJITLoaderPerfStart(const char *Data, uint64_t Size) {
+  using namespace orc::shared;
+  return WrapperFunction<SPSError()>::handle(Data, Size, badOS).release();
+}
+
+extern "C" llvm::orc::shared::CWrapperFunctionResult
+llvm_orc_registerJITLoaderPerfEnd(const char *Data, uint64_t Size) {
+  using namespace orc::shared;
+  return WrapperFunction<SPSError()>::handle(Data, Size, badOS).release();
+}
+
+#endif
\ No newline at end of file