[ORC] Add DWARFContext generation from LinkGraphs, use in perf support.

This patch adds line numbers to perf jitdump records emitted by the
PerfSupportPlugin, by parsing and using a DWARFContext from preserved debug
sections.

To avoid making the OrcJIT library depend on DebugInfoDWARF this patch
introduces a new OrcDebugging library.

Reviewed By: lhames

Differential Revision: https://reviews.llvm.org/D146391

llvm/include/llvm/ExecutionEngine/Orc/Debugging/DebugInfoSupport.h

@@ -0,0 +1,62 @@
+//===--- DebugInfoSupport.h ---- Utils for debug info 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Utilities to preserve and parse debug info from LinkGraphs.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_ORC_DEBUGINFOSUPPORT_H
+#define LLVM_EXECUTIONENGINE_ORC_DEBUGINFOSUPPORT_H
+
+#include "llvm/ExecutionEngine/Orc/Core.h"
+#include "llvm/ExecutionEngine/Orc/ObjectLinkingLayer.h"
+
+#include "llvm/DebugInfo/DWARF/DWARFContext.h"
+
+namespace llvm {
+
+namespace orc {
+
+Error preserveDebugSections(jitlink::LinkGraph &G);
+// The backing stringmap is also returned, for memory liftime management.
+Expected<std::pair<std::unique_ptr<DWARFContext>,
+                   StringMap<std::unique_ptr<MemoryBuffer>>>>
+createDWARFContext(jitlink::LinkGraph &G);
+
+// Thin wrapper around preserveDebugSections to be used as a standalone plugin.
+class DebugInfoPreservationPlugin : public ObjectLinkingLayer::Plugin {
+public:
+  void modifyPassConfig(MaterializationResponsibility &MR,
+                        jitlink::LinkGraph &LG,
+                        jitlink::PassConfiguration &PassConfig) override {
+    PassConfig.PrePrunePasses.push_back(preserveDebugSections);
+  }
+
+  Error notifyRemovingResources(JITDylib &JD, ResourceKey K) override {
+    // Do nothing.
+    return Error::success();
+  }
+  Error notifyFailed(MaterializationResponsibility &MR) override {
+    // Do nothing.
+    return Error::success();
+  }
+  void notifyTransferringResources(JITDylib &JD, ResourceKey DstKey,
+                                   ResourceKey SrcKey) override {
+    // Do nothing.
+  }
+
+  static Expected<std::unique_ptr<DebugInfoPreservationPlugin>> Create() {
+    return std::make_unique<DebugInfoPreservationPlugin>();
+  }
+};
+
+} // namespace orc
+
+} // namespace llvm
+
+#endif

llvm/include/llvm/ExecutionEngine/Orc/Debugging/PerfSupportPlugin.h

@@ -29,7 +29,8 @@ public:
   PerfSupportPlugin(ExecutorProcessControl &EPC,
                     ExecutorAddr RegisterPerfStartAddr,
                     ExecutorAddr RegisterPerfEndAddr,
-                    ExecutorAddr RegisterPerfImplAddr, bool EmitUnwindInfo);
+                    ExecutorAddr RegisterPerfImplAddr, bool EmitDebugInfo,
+                    bool EmitUnwindInfo);
   ~PerfSupportPlugin();
 
   void modifyPassConfig(MaterializationResponsibility &MR,
@@ -48,7 +49,8 @@ public:
                                    ResourceKey SrcKey) override {}
 
   static Expected<std::unique_ptr<PerfSupportPlugin>>
-  Create(ExecutorProcessControl &EPC, JITDylib &JD, bool EmitUnwindInfo);
+  Create(ExecutorProcessControl &EPC, JITDylib &JD, bool EmitDebugInfo,
+         bool EmitUnwindInfo);
 
 private:
   ExecutorProcessControl &EPC;
@@ -56,6 +58,7 @@ private:
   ExecutorAddr RegisterPerfEndAddr;
   ExecutorAddr RegisterPerfImplAddr;
   std::atomic<uint64_t> CodeIndex;
+  bool EmitDebugInfo;
   bool EmitUnwindInfo;
 };
 

llvm/lib/ExecutionEngine/Orc/CMakeLists.txt

@@ -42,7 +42,6 @@ add_llvm_component_library(LLVMOrcJIT
   ObjectTransformLayer.cpp
   OrcABISupport.cpp
   OrcV2CBindings.cpp
-  PerfSupportPlugin.cpp
   RTDyldObjectLinkingLayer.cpp
   SimpleRemoteEPC.cpp
   Speculation.cpp
@@ -78,6 +77,7 @@ add_llvm_component_library(LLVMOrcJIT
   TransformUtils
   )
 
+add_subdirectory(Debugging)
 add_subdirectory(Shared)
 add_subdirectory(TargetProcess)
 

llvm/lib/ExecutionEngine/Orc/Debugging/CMakeLists.txt

@@ -0,0 +1,22 @@
+if( CMAKE_HOST_UNIX AND HAVE_LIBRT )
+  set(rt_lib rt)
+endif()
+
+add_llvm_component_library(LLVMOrcDebugging
+  DebugInfoSupport.cpp
+  PerfSupportPlugin.cpp
+
+  ADDITIONAL_HEADER_DIRS
+  ${LLVM_MAIN_INCLUDE_DIR}/llvm/ExecutionEngine/Orc/Debugging/
+
+  LINK_LIBS
+  ${LLVM_PTHREAD_LIB}
+  ${rt_lib}
+
+  LINK_COMPONENTS
+  DebugInfoDWARF
+  OrcJIT
+  OrcShared
+  Support
+  TargetParser
+  )

llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp

@@ -0,0 +1,120 @@
+//===--- DebugInfoSupport.cpp -- Utils for debug info 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Utilities to preserve and parse debug info from LinkGraphs.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/Debugging/DebugInfoSupport.h"
+
+#include "llvm/Support/SmallVectorMemoryBuffer.h"
+
+#define DEBUG_TYPE "orc"
+
+using namespace llvm;
+using namespace llvm::orc;
+using namespace llvm::jitlink;
+
+namespace {
+static DenseSet<StringRef> DWARFSectionNames = {
+#define HANDLE_DWARF_SECTION(ENUM_NAME, ELF_NAME, CMDLINE_NAME, OPTION)        \
+  StringRef(ELF_NAME),
+#include "llvm/BinaryFormat/Dwarf.def"
+#undef HANDLE_DWARF_SECTION
+};
+
+// We might be able to drop relocations to symbols that do end up
+// being pruned by the linker, but for now we just preserve all
+static void preserveDWARFSection(LinkGraph &G, Section &Sec) {
+  DenseMap<Block *, Symbol *> Preserved;
+  for (auto Sym : Sec.symbols()) {
+    if (Sym->isLive())
+      Preserved[&Sym->getBlock()] = Sym;
+    else if (!Preserved.count(&Sym->getBlock()))
+      Preserved[&Sym->getBlock()] = Sym;
+  }
+  for (auto Block : Sec.blocks()) {
+    auto &PSym = Preserved[Block];
+    if (!PSym)
+      PSym = &G.addAnonymousSymbol(*Block, 0, 0, false, true);
+    else if (!PSym->isLive())
+      PSym->setLive(true);
+  }
+}
+
+static SmallVector<char, 0> getSectionData(Section &Sec) {
+  SmallVector<char, 0> SecData;
+  SmallVector<Block *, 8> SecBlocks(Sec.blocks().begin(), Sec.blocks().end());
+  std::sort(SecBlocks.begin(), SecBlocks.end(), [](Block *LHS, Block *RHS) {
+    return LHS->getAddress() < RHS->getAddress();
+  });
+  // Convert back to what object file would have, one blob of section content
+  // Assumes all zerofill
+  // TODO handle alignment?
+  // TODO handle alignment offset?
+  for (auto *Block : SecBlocks) {
+    if (Block->isZeroFill())
+      SecData.resize(SecData.size() + Block->getSize(), 0);
+    else
+      SecData.append(Block->getContent().begin(), Block->getContent().end());
+  }
+  return SecData;
+}
+
+static void dumpDWARFContext(DWARFContext &DC) {
+  auto options = llvm::DIDumpOptions();
+  options.DumpType &= ~DIDT_UUID;
+  options.DumpType &= ~(1 << DIDT_ID_DebugFrame);
+  LLVM_DEBUG(DC.dump(dbgs(), options));
+}
+
+} // namespace
+
+Error llvm::orc::preserveDebugSections(LinkGraph &G) {
+  if (!G.getTargetTriple().isOSBinFormatELF()) {
+    return make_error<StringError>(
+        "preserveDebugSections only supports ELF LinkGraphs!",
+        inconvertibleErrorCode());
+  }
+  for (auto &Sec : G.sections()) {
+    if (DWARFSectionNames.count(Sec.getName())) {
+      LLVM_DEBUG(dbgs() << "Preserving DWARF section " << Sec.getName()
+                        << "\n");
+      preserveDWARFSection(G, Sec);
+    }
+  }
+  return Error::success();
+}
+
+Expected<std::pair<std::unique_ptr<DWARFContext>,
+                   StringMap<std::unique_ptr<MemoryBuffer>>>>
+llvm::orc::createDWARFContext(LinkGraph &G) {
+  if (!G.getTargetTriple().isOSBinFormatELF()) {
+    return make_error<StringError>(
+        "createDWARFContext only supports ELF LinkGraphs!",
+        inconvertibleErrorCode());
+  }
+  StringMap<std::unique_ptr<MemoryBuffer>> DWARFSectionData;
+  for (auto &Sec : G.sections()) {
+    if (DWARFSectionNames.count(Sec.getName())) {
+      auto SecData = getSectionData(Sec);
+      auto Name = Sec.getName();
+      // DWARFContext expects the section name to not start with a dot
+      if (Name.startswith("."))
+        Name = Name.drop_front();
+      LLVM_DEBUG(dbgs() << "Creating DWARFContext section " << Name
+                        << " with size " << SecData.size() << "\n");
+      DWARFSectionData[Name] =
+          std::make_unique<SmallVectorMemoryBuffer>(std::move(SecData));
+    }
+  }
+  auto Ctx = DWARFContext::create(DWARFSectionData, G.getPointerSize(),
+                                  G.getEndianness() == support::little);
+  dumpDWARFContext(*Ctx);
+  return std::make_pair(std::move(Ctx), std::move(DWARFSectionData));
+}

llvm/lib/ExecutionEngine/Orc/Debugging/PerfSupportPlugin.cpp

@@ -10,13 +10,12 @@
 //
 //===----------------------------------------------------------------------===//
 
-#include "llvm/ExecutionEngine/Orc/PerfSupportPlugin.h"
+#include "llvm/ExecutionEngine/Orc/Debugging/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/Debugging/DebugInfoSupport.h"
 #include "llvm/ExecutionEngine/Orc/LookupAndRecordAddrs.h"
+#include "llvm/ExecutionEngine/Orc/Shared/WrapperFunctionUtils.h"
 
 #define DEBUG_TYPE "orc"
 
@@ -114,11 +113,7 @@ getCodeLoadRecord(const Symbol &Sym, std::atomic<uint64_t> &CodeIndex) {
 }
 
 static std::optional<PerfJITDebugInfoRecord>
-getDebugInfoRecord(const Symbol &Sym, DWARFContext *DC) {
-  if (!DC) {
-    LLVM_DEBUG(dbgs() << "No debug info available\n");
-    return std::nullopt;
-  }
+getDebugInfoRecord(const Symbol &Sym, DWARFContext &DC) {
   auto &Section = Sym.getBlock().getSection();
   auto Addr = Sym.getAddress();
   auto Size = Sym.getSize();
@@ -127,7 +122,7 @@ getDebugInfoRecord(const Symbol &Sym, DWARFContext *DC) {
                     << " at address " << Addr.getValue() << " with size "
                     << Size << "\n"
                     << "Section ordinal: " << Section.getOrdinal() << "\n");
-  auto LInfo = DC->getLineInfoForAddressRange(
+  auto LInfo = DC.getLineInfoForAddressRange(
       SAddr, Size, DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath);
   if (LInfo.empty()) {
     // No line info available
@@ -218,16 +213,29 @@ getUnwindingRecord(LinkGraph &G) {
 }
 
 static PerfJITRecordBatch getRecords(ExecutionSession &ES, LinkGraph &G,
-                                     DWARFContext *DC,
                                      std::atomic<uint64_t> &CodeIndex,
-                                     bool EmitUnwindInfo) {
+                                     bool EmitDebugInfo, bool EmitUnwindInfo) {
+  std::unique_ptr<DWARFContext> DC;
+  StringMap<std::unique_ptr<MemoryBuffer>> DCBacking;
+  if (EmitDebugInfo) {
+    auto EDC = createDWARFContext(G);
+    if (!EDC) {
+      ES.reportError(EDC.takeError());
+      EmitDebugInfo = false;
+    } else {
+      DC = std::move(EDC->first);
+      DCBacking = std::move(EDC->second);
+    }
+  }
   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));
+    if (EmitDebugInfo) {
+      auto DebugInfo = getDebugInfoRecord(*Sym, *DC);
+      if (DebugInfo)
+        Batch.DebugInfoRecords.push_back(std::move(*DebugInfo));
+    }
     Batch.CodeLoadRecords.push_back(getCodeLoadRecord(*Sym, CodeIndex));
   }
   if (EmitUnwindInfo) {
@@ -248,11 +256,11 @@ PerfSupportPlugin::PerfSupportPlugin(ExecutorProcessControl &EPC,
                                      ExecutorAddr RegisterPerfStartAddr,
                                      ExecutorAddr RegisterPerfEndAddr,
                                      ExecutorAddr RegisterPerfImplAddr,
-                                     bool EmitUnwindInfo)
+                                     bool EmitDebugInfo, bool EmitUnwindInfo)
     : EPC(EPC), RegisterPerfStartAddr(RegisterPerfStartAddr),
       RegisterPerfEndAddr(RegisterPerfEndAddr),
       RegisterPerfImplAddr(RegisterPerfImplAddr), CodeIndex(0),
-      EmitUnwindInfo(EmitUnwindInfo) {
+      EmitDebugInfo(EmitDebugInfo), EmitUnwindInfo(EmitUnwindInfo) {
   cantFail(EPC.callSPSWrapper<void()>(RegisterPerfStartAddr));
 }
 PerfSupportPlugin::~PerfSupportPlugin() {
@@ -263,10 +271,8 @@ void PerfSupportPlugin::modifyPassConfig(MaterializationResponsibility &MR,
                                          LinkGraph &G,
                                          PassConfiguration &Config) {
   Config.PostFixupPasses.push_back([this](LinkGraph &G) {
-    // TODO get an actual DWARFContext for line info
-    DWARFContext *DWC = nullptr;
-    auto Batch = getRecords(EPC.getExecutionSession(), G, DWC, CodeIndex,
-                            EmitUnwindInfo);
+    auto Batch = getRecords(EPC.getExecutionSession(), G, CodeIndex,
+                            EmitDebugInfo, EmitUnwindInfo);
     G.allocActions().push_back(
         {cantFail(shared::WrapperFunctionCall::Create<
                   shared::SPSArgList<shared::SPSPerfJITRecordBatch>>(
@@ -278,7 +284,7 @@ void PerfSupportPlugin::modifyPassConfig(MaterializationResponsibility &MR,
 
 Expected<std::unique_ptr<PerfSupportPlugin>>
 PerfSupportPlugin::Create(ExecutorProcessControl &EPC, JITDylib &JD,
-                          bool EmitUnwindInfo) {
+                          bool EmitDebugInfo, bool EmitUnwindInfo) {
   if (!EPC.getTargetTriple().isOSBinFormatELF()) {
     return make_error<StringError>(
         "Perf support only available for ELF LinkGraphs!",
@@ -293,5 +299,5 @@ PerfSupportPlugin::Create(ExecutorProcessControl &EPC, JITDylib &JD,
            {ES.intern(RegisterPerfImplSymbolName), &ImplAddr}}))
     return std::move(Err);
   return std::make_unique<PerfSupportPlugin>(EPC, StartAddr, EndAddr, ImplAddr,
-                                             EmitUnwindInfo);
+                                             EmitDebugInfo, EmitUnwindInfo);
 }

llvm/tools/llvm-jitlink/CMakeLists.txt

@@ -11,6 +11,7 @@ set(LLVM_LINK_COMPONENTS
   JITLink
   MC
   Object
+  OrcDebugging
   OrcJIT
   OrcShared
   OrcTargetProcess

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

@@ -19,6 +19,8 @@
 #include "llvm/ExecutionEngine/Orc/COFFVCRuntimeSupport.h"
 #include "llvm/ExecutionEngine/Orc/DebugObjectManagerPlugin.h"
 #include "llvm/ExecutionEngine/Orc/DebuggerSupportPlugin.h"
+#include "llvm/ExecutionEngine/Orc/Debugging/DebugInfoSupport.h"
+#include "llvm/ExecutionEngine/Orc/Debugging/PerfSupportPlugin.h"
 #include "llvm/ExecutionEngine/Orc/ELFNixPlatform.h"
 #include "llvm/ExecutionEngine/Orc/EPCDebugObjectRegistrar.h"
 #include "llvm/ExecutionEngine/Orc/EPCDynamicLibrarySearchGenerator.h"
@@ -28,7 +30,6 @@
 #include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
 #include "llvm/ExecutionEngine/Orc/MapperJITLinkMemoryManager.h"
 #include "llvm/ExecutionEngine/Orc/ObjectFileInterface.h"
-#include "llvm/ExecutionEngine/Orc/PerfSupportPlugin.h"
 #include "llvm/ExecutionEngine/Orc/Shared/OrcRTBridge.h"
 #include "llvm/ExecutionEngine/Orc/TargetProcess/JITLoaderGDB.h"
 #include "llvm/ExecutionEngine/Orc/TargetProcess/JITLoaderPerf.h"
@@ -990,9 +991,11 @@ Session::Session(std::unique_ptr<ExecutorProcessControl> EPC, Error &Err)
     ObjLayer.addPlugin(ExitOnErr(
         GDBJITDebugInfoRegistrationPlugin::Create(this->ES, *MainJD, TT)));
 
-  if (PerfSupport && TT.isOSBinFormatELF())
+  if (PerfSupport && TT.isOSBinFormatELF()) {
+    ObjLayer.addPlugin(ExitOnErr(DebugInfoPreservationPlugin::Create()));
     ObjLayer.addPlugin(ExitOnErr(PerfSupportPlugin::Create(
-        this->ES.getExecutorProcessControl(), *MainJD, true)));
+        this->ES.getExecutorProcessControl(), *MainJD, true, true)));
+  }
 
   // Set up the platform.
   if (TT.isOSBinFormatMachO() && !OrcRuntime.empty()) {