1 files changed, 506 insertions, 0 deletions
diff --git a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
new file mode 100644
index 000000000000..15c3aa79a2a8
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
@@ -0,0 +1,506 @@
+//===------ MachOPlatform.cpp - Utilities for executing MachO in Orc ------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
+
+#include "llvm/BinaryFormat/MachO.h"
+#include "llvm/ExecutionEngine/Orc/DebugUtils.h"
+#include "llvm/Support/BinaryByteStream.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "orc"
+
+namespace {
+
+struct objc_class;
+struct objc_image_info;
+struct objc_object;
+struct objc_selector;
+
+using Class = objc_class *;
+using id = objc_object *;
+using SEL = objc_selector *;
+
+using ObjCMsgSendTy = id (*)(id, SEL, ...);
+using ObjCReadClassPairTy = Class (*)(Class, const objc_image_info *);
+using SelRegisterNameTy = SEL (*)(const char *);
+
+enum class ObjCRegistrationAPI { Uninitialized, Unavailable, Initialized };
+
+ObjCRegistrationAPI ObjCRegistrationAPIState =
+    ObjCRegistrationAPI::Uninitialized;
+ObjCMsgSendTy objc_msgSend = nullptr;
+ObjCReadClassPairTy objc_readClassPair = nullptr;
+SelRegisterNameTy sel_registerName = nullptr;
+
+} // end anonymous namespace
+
+namespace llvm {
+namespace orc {
+
+template <typename FnTy>
+static Error setUpObjCRegAPIFunc(FnTy &Target, sys::DynamicLibrary &LibObjC,
+                                 const char *Name) {
+  if (void *Addr = LibObjC.getAddressOfSymbol(Name))
+    Target = reinterpret_cast<FnTy>(Addr);
+  else
+    return make_error<StringError>(
+        (Twine("Could not find address for ") + Name).str(),
+        inconvertibleErrorCode());
+  return Error::success();
+}
+
+Error enableObjCRegistration(const char *PathToLibObjC) {
+  // If we've already tried to initialize then just bail out.
+  if (ObjCRegistrationAPIState != ObjCRegistrationAPI::Uninitialized)
+    return Error::success();
+
+  ObjCRegistrationAPIState = ObjCRegistrationAPI::Unavailable;
+
+  std::string ErrMsg;
+  auto LibObjC =
+      sys::DynamicLibrary::getPermanentLibrary(PathToLibObjC, &ErrMsg);
+
+  if (!LibObjC.isValid())
+    return make_error<StringError>(std::move(ErrMsg), inconvertibleErrorCode());
+
+  if (auto Err = setUpObjCRegAPIFunc(objc_msgSend, LibObjC, "objc_msgSend"))
+    return Err;
+  if (auto Err = setUpObjCRegAPIFunc(objc_readClassPair, LibObjC,
+                                     "objc_readClassPair"))
+    return Err;
+  if (auto Err =
+          setUpObjCRegAPIFunc(sel_registerName, LibObjC, "sel_registerName"))
+    return Err;
+
+  ObjCRegistrationAPIState = ObjCRegistrationAPI::Initialized;
+  return Error::success();
+}
+
+bool objCRegistrationEnabled() {
+  return ObjCRegistrationAPIState == ObjCRegistrationAPI::Initialized;
+}
+
+void MachOJITDylibInitializers::runModInits() const {
+  for (const auto &ModInit : ModInitSections) {
+    for (uint64_t I = 0; I != ModInit.NumPtrs; ++I) {
+      auto *InitializerAddr = jitTargetAddressToPointer<uintptr_t *>(
+          ModInit.Address + (I * sizeof(uintptr_t)));
+      auto *Initializer =
+          jitTargetAddressToFunction<void (*)()>(*InitializerAddr);
+      Initializer();
+    }
+  }
+}
+
+void MachOJITDylibInitializers::registerObjCSelectors() const {
+  assert(objCRegistrationEnabled() && "ObjC registration not enabled.");
+
+  for (const auto &ObjCSelRefs : ObjCSelRefsSections) {
+    for (uint64_t I = 0; I != ObjCSelRefs.NumPtrs; ++I) {
+      auto SelEntryAddr = ObjCSelRefs.Address + (I * sizeof(uintptr_t));
+      const auto *SelName =
+          *jitTargetAddressToPointer<const char **>(SelEntryAddr);
+      auto Sel = sel_registerName(SelName);
+      *jitTargetAddressToPointer<SEL *>(SelEntryAddr) = Sel;
+    }
+  }
+}
+
+Error MachOJITDylibInitializers::registerObjCClasses() const {
+  assert(objCRegistrationEnabled() && "ObjC registration not enabled.");
+
+  struct ObjCClassCompiled {
+    void *Metaclass;
+    void *Parent;
+    void *Cache1;
+    void *Cache2;
+    void *Data;
+  };
+
+  auto *ImageInfo =
+      jitTargetAddressToPointer<const objc_image_info *>(ObjCImageInfoAddr);
+  auto ClassSelector = sel_registerName("class");
+
+  for (const auto &ObjCClassList : ObjCClassListSections) {
+    for (uint64_t I = 0; I != ObjCClassList.NumPtrs; ++I) {
+      auto ClassPtrAddr = ObjCClassList.Address + (I * sizeof(uintptr_t));
+      auto Cls = *jitTargetAddressToPointer<Class *>(ClassPtrAddr);
+      auto *ClassCompiled =
+          *jitTargetAddressToPointer<ObjCClassCompiled **>(ClassPtrAddr);
+      objc_msgSend(reinterpret_cast<id>(ClassCompiled->Parent), ClassSelector);
+      auto Registered = objc_readClassPair(Cls, ImageInfo);
+
+      // FIXME: Improve diagnostic by reporting the failed class's name.
+      if (Registered != Cls)
+        return make_error<StringError>("Unable to register Objective-C class",
+                                       inconvertibleErrorCode());
+    }
+  }
+  return Error::success();
+}
+
+MachOPlatform::MachOPlatform(
+    ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
+    std::unique_ptr<MemoryBuffer> StandardSymbolsObject)
+    : ES(ES), ObjLinkingLayer(ObjLinkingLayer),
+      StandardSymbolsObject(std::move(StandardSymbolsObject)) {
+  ObjLinkingLayer.addPlugin(std::make_unique<InitScraperPlugin>(*this));
+}
+
+Error MachOPlatform::setupJITDylib(JITDylib &JD) {
+  auto ObjBuffer = MemoryBuffer::getMemBuffer(
+      StandardSymbolsObject->getMemBufferRef(), false);
+  return ObjLinkingLayer.add(JD, std::move(ObjBuffer));
+}
+
+Error MachOPlatform::notifyAdding(JITDylib &JD, const MaterializationUnit &MU) {
+  const auto &InitSym = MU.getInitializerSymbol();
+  if (!InitSym)
+    return Error::success();
+
+  RegisteredInitSymbols[&JD].add(InitSym,
+                                 SymbolLookupFlags::WeaklyReferencedSymbol);
+  LLVM_DEBUG({
+    dbgs() << "MachOPlatform: Registered init symbol " << *InitSym << " for MU "
+           << MU.getName() << "\n";
+  });
+  return Error::success();
+}
+
+Error MachOPlatform::notifyRemoving(JITDylib &JD, VModuleKey K) {
+  llvm_unreachable("Not supported yet");
+}
+
+Expected<MachOPlatform::InitializerSequence>
+MachOPlatform::getInitializerSequence(JITDylib &JD) {
+
+  LLVM_DEBUG({
+    dbgs() << "MachOPlatform: Building initializer sequence for "
+           << JD.getName() << "\n";
+  });
+
+  std::vector<JITDylib *> DFSLinkOrder;
+
+  while (true) {
+
+    DenseMap<JITDylib *, SymbolLookupSet> NewInitSymbols;
+
+    ES.runSessionLocked([&]() {
+      DFSLinkOrder = getDFSLinkOrder(JD);
+
+      for (auto *InitJD : DFSLinkOrder) {
+        auto RISItr = RegisteredInitSymbols.find(InitJD);
+        if (RISItr != RegisteredInitSymbols.end()) {
+          NewInitSymbols[InitJD] = std::move(RISItr->second);
+          RegisteredInitSymbols.erase(RISItr);
+        }
+      }
+    });
+
+    if (NewInitSymbols.empty())
+      break;
+
+    LLVM_DEBUG({
+      dbgs() << "MachOPlatform: Issuing lookups for new init symbols: "
+                "(lookup may require multiple rounds)\n";
+      for (auto &KV : NewInitSymbols)
+        dbgs() << "  \"" << KV.first->getName() << "\": " << KV.second << "\n";
+    });
+
+    // Outside the lock, issue the lookup.
+    if (auto R = lookupInitSymbols(JD.getExecutionSession(), NewInitSymbols))
+      ; // Nothing to do in the success case.
+    else
+      return R.takeError();
+  }
+
+  LLVM_DEBUG({
+    dbgs() << "MachOPlatform: Init symbol lookup complete, building init "
+              "sequence\n";
+  });
+
+  // Lock again to collect the initializers.
+  InitializerSequence FullInitSeq;
+  {
+    std::lock_guard<std::mutex> Lock(InitSeqsMutex);
+    for (auto *InitJD : reverse(DFSLinkOrder)) {
+      LLVM_DEBUG({
+        dbgs() << "MachOPlatform: Appending inits for \"" << InitJD->getName()
+               << "\" to sequence\n";
+      });
+      auto ISItr = InitSeqs.find(InitJD);
+      if (ISItr != InitSeqs.end()) {
+        FullInitSeq.emplace_back(InitJD, std::move(ISItr->second));
+        InitSeqs.erase(ISItr);
+      }
+    }
+  }
+
+  return FullInitSeq;
+}
+
+Expected<MachOPlatform::DeinitializerSequence>
+MachOPlatform::getDeinitializerSequence(JITDylib &JD) {
+  std::vector<JITDylib *> DFSLinkOrder = getDFSLinkOrder(JD);
+
+  DeinitializerSequence FullDeinitSeq;
+  {
+    std::lock_guard<std::mutex> Lock(InitSeqsMutex);
+    for (auto *DeinitJD : DFSLinkOrder) {
+      FullDeinitSeq.emplace_back(DeinitJD, MachOJITDylibDeinitializers());
+    }
+  }
+
+  return FullDeinitSeq;
+}
+
+std::vector<JITDylib *> MachOPlatform::getDFSLinkOrder(JITDylib &JD) {
+  std::vector<JITDylib *> Result, WorkStack({&JD});
+  DenseSet<JITDylib *> Visited;
+
+  while (!WorkStack.empty()) {
+    auto *NextJD = WorkStack.back();
+    WorkStack.pop_back();
+    if (Visited.count(NextJD))
+      continue;
+    Visited.insert(NextJD);
+    Result.push_back(NextJD);
+    NextJD->withLinkOrderDo([&](const JITDylibSearchOrder &LO) {
+      for (auto &KV : LO)
+        WorkStack.push_back(KV.first);
+    });
+  }
+
+  return Result;
+}
+
+void MachOPlatform::registerInitInfo(
+    JITDylib &JD, JITTargetAddress ObjCImageInfoAddr,
+    MachOJITDylibInitializers::SectionExtent ModInits,
+    MachOJITDylibInitializers::SectionExtent ObjCSelRefs,
+    MachOJITDylibInitializers::SectionExtent ObjCClassList) {
+  std::lock_guard<std::mutex> Lock(InitSeqsMutex);
+
+  auto &InitSeq = InitSeqs[&JD];
+
+  InitSeq.setObjCImageInfoAddr(ObjCImageInfoAddr);
+
+  if (ModInits.Address)
+    InitSeq.addModInitsSection(std::move(ModInits));
+
+  if (ObjCSelRefs.Address)
+    InitSeq.addObjCSelRefsSection(std::move(ObjCSelRefs));
+
+  if (ObjCClassList.Address)
+    InitSeq.addObjCClassListSection(std::move(ObjCClassList));
+}
+
+static Expected<MachOJITDylibInitializers::SectionExtent>
+getSectionExtent(jitlink::LinkGraph &G, StringRef SectionName) {
+  auto *Sec = G.findSectionByName(SectionName);
+  if (!Sec)
+    return MachOJITDylibInitializers::SectionExtent();
+  jitlink::SectionRange R(*Sec);
+  if (R.getSize() % G.getPointerSize() != 0)
+    return make_error<StringError>(SectionName + " section size is not a "
+                                                 "multiple of the pointer size",
+                                   inconvertibleErrorCode());
+  return MachOJITDylibInitializers::SectionExtent(
+      R.getStart(), R.getSize() / G.getPointerSize());
+}
+
+void MachOPlatform::InitScraperPlugin::modifyPassConfig(
+    MaterializationResponsibility &MR, const Triple &TT,
+    jitlink::PassConfiguration &Config) {
+
+  Config.PrePrunePasses.push_back([this, &MR](jitlink::LinkGraph &G) -> Error {
+    JITLinkSymbolVector InitSectionSymbols;
+    preserveInitSectionIfPresent(InitSectionSymbols, G, "__mod_init_func");
+    preserveInitSectionIfPresent(InitSectionSymbols, G, "__objc_selrefs");
+    preserveInitSectionIfPresent(InitSectionSymbols, G, "__objc_classlist");
+
+    if (!InitSymbolDeps.empty()) {
+      std::lock_guard<std::mutex> Lock(InitScraperMutex);
+      InitSymbolDeps[&MR] = std::move(InitSectionSymbols);
+    }
+
+    if (auto Err = processObjCImageInfo(G, MR))
+      return Err;
+
+    return Error::success();
+  });
+
+  Config.PostFixupPasses.push_back([this, &JD = MR.getTargetJITDylib()](
+                                       jitlink::LinkGraph &G) -> Error {
+    MachOJITDylibInitializers::SectionExtent ModInits, ObjCSelRefs,
+        ObjCClassList;
+
+    JITTargetAddress ObjCImageInfoAddr = 0;
+    if (auto *ObjCImageInfoSec = G.findSectionByName("__objc_image_info")) {
+      if (auto Addr = jitlink::SectionRange(*ObjCImageInfoSec).getStart()) {
+        ObjCImageInfoAddr = Addr;
+        dbgs() << "Recorded __objc_imageinfo @ " << formatv("{0:x16}", Addr);
+      }
+    }
+
+    // Record __mod_init_func.
+    if (auto ModInitsOrErr = getSectionExtent(G, "__mod_init_func"))
+      ModInits = std::move(*ModInitsOrErr);
+    else
+      return ModInitsOrErr.takeError();
+
+    // Record __objc_selrefs.
+    if (auto ObjCSelRefsOrErr = getSectionExtent(G, "__objc_selrefs"))
+      ObjCSelRefs = std::move(*ObjCSelRefsOrErr);
+    else
+      return ObjCSelRefsOrErr.takeError();
+
+    // Record __objc_classlist.
+    if (auto ObjCClassListOrErr = getSectionExtent(G, "__objc_classlist"))
+      ObjCClassList = std::move(*ObjCClassListOrErr);
+    else
+      return ObjCClassListOrErr.takeError();
+
+    // Dump the scraped inits.
+    LLVM_DEBUG({
+      dbgs() << "MachOPlatform: Scraped " << G.getName() << " init sections:\n";
+      dbgs() << "  __objc_selrefs: ";
+      if (ObjCSelRefs.NumPtrs)
+        dbgs() << ObjCSelRefs.NumPtrs << " pointer(s) at "
+               << formatv("{0:x16}", ObjCSelRefs.Address) << "\n";
+      else
+        dbgs() << "none\n";
+
+      dbgs() << "  __objc_classlist: ";
+      if (ObjCClassList.NumPtrs)
+        dbgs() << ObjCClassList.NumPtrs << " pointer(s) at "
+               << formatv("{0:x16}", ObjCClassList.Address) << "\n";
+      else
+        dbgs() << "none\n";
+
+      dbgs() << "  __mod_init_func: ";
+      if (ModInits.NumPtrs)
+        dbgs() << ModInits.NumPtrs << " pointer(s) at "
+               << formatv("{0:x16}", ModInits.Address) << "\n";
+      else
+        dbgs() << "none\n";
+    });
+
+    MP.registerInitInfo(JD, ObjCImageInfoAddr, std::move(ModInits),
+                        std::move(ObjCSelRefs), std::move(ObjCClassList));
+
+    return Error::success();
+  });
+}
+
+ObjectLinkingLayer::Plugin::LocalDependenciesMap
+MachOPlatform::InitScraperPlugin::getSyntheticSymbolLocalDependencies(
+    MaterializationResponsibility &MR) {
+  std::lock_guard<std::mutex> Lock(InitScraperMutex);
+  auto I = InitSymbolDeps.find(&MR);
+  if (I != InitSymbolDeps.end()) {
+    LocalDependenciesMap Result;
+    Result[MR.getInitializerSymbol()] = std::move(I->second);
+    InitSymbolDeps.erase(&MR);
+    return Result;
+  }
+  return LocalDependenciesMap();
+}
+
+void MachOPlatform::InitScraperPlugin::preserveInitSectionIfPresent(
+    JITLinkSymbolVector &Symbols, jitlink::LinkGraph &G,
+    StringRef SectionName) {
+  if (auto *Sec = G.findSectionByName(SectionName)) {
+    auto SecBlocks = Sec->blocks();
+    if (!llvm::empty(SecBlocks))
+      Symbols.push_back(
+          &G.addAnonymousSymbol(**SecBlocks.begin(), 0, 0, false, true));
+  }
+}
+
+Error MachOPlatform::InitScraperPlugin::processObjCImageInfo(
+    jitlink::LinkGraph &G, MaterializationResponsibility &MR) {
+
+  // If there's an ObjC imagine info then either
+  //   (1) It's the first __objc_imageinfo we've seen in this JITDylib. In
+  //       this case we name and record it.
+  // OR
+  //   (2) We already have a recorded __objc_imageinfo for this JITDylib,
+  //       in which case we just verify it.
+  auto *ObjCImageInfo = G.findSectionByName("__objc_imageinfo");
+  if (!ObjCImageInfo)
+    return Error::success();
+
+  auto ObjCImageInfoBlocks = ObjCImageInfo->blocks();
+
+  // Check that the section is not empty if present.
+  if (llvm::empty(ObjCImageInfoBlocks))
+    return make_error<StringError>("Empty __objc_imageinfo section in " +
+                                       G.getName(),
+                                   inconvertibleErrorCode());
+
+  // Check that there's only one block in the section.
+  if (std::next(ObjCImageInfoBlocks.begin()) != ObjCImageInfoBlocks.end())
+    return make_error<StringError>("Multiple blocks in __objc_imageinfo "
+                                   "section in " +
+                                       G.getName(),
+                                   inconvertibleErrorCode());
+
+  // Check that the __objc_imageinfo section is unreferenced.
+  // FIXME: We could optimize this check if Symbols had a ref-count.
+  for (auto &Sec : G.sections()) {
+    if (&Sec != ObjCImageInfo)
+      for (auto *B : Sec.blocks())
+        for (auto &E : B->edges())
+          if (E.getTarget().isDefined() &&
+              &E.getTarget().getBlock().getSection() == ObjCImageInfo)
+            return make_error<StringError>("__objc_imageinfo is referenced "
+                                           "within file " +
+                                               G.getName(),
+                                           inconvertibleErrorCode());
+  }
+
+  auto &ObjCImageInfoBlock = **ObjCImageInfoBlocks.begin();
+  auto *ObjCImageInfoData = ObjCImageInfoBlock.getContent().data();
+  auto Version = support::endian::read32(ObjCImageInfoData, G.getEndianness());
+  auto Flags =
+      support::endian::read32(ObjCImageInfoData + 4, G.getEndianness());
+
+  // Lock the mutex while we verify / update the ObjCImageInfos map.
+  std::lock_guard<std::mutex> Lock(InitScraperMutex);
+
+  auto ObjCImageInfoItr = ObjCImageInfos.find(&MR.getTargetJITDylib());
+  if (ObjCImageInfoItr != ObjCImageInfos.end()) {
+    // We've already registered an __objc_imageinfo section. Verify the
+    // content of this new section matches, then delete it.
+    if (ObjCImageInfoItr->second.first != Version)
+      return make_error<StringError>(
+          "ObjC version in " + G.getName() +
+              " does not match first registered version",
+          inconvertibleErrorCode());
+    if (ObjCImageInfoItr->second.second != Flags)
+      return make_error<StringError>("ObjC flags in " + G.getName() +
+                                         " do not match first registered flags",
+                                     inconvertibleErrorCode());
+
+    // __objc_imageinfo is valid. Delete the block.
+    for (auto *S : ObjCImageInfo->symbols())
+      G.removeDefinedSymbol(*S);
+    G.removeBlock(ObjCImageInfoBlock);
+  } else {
+    // We haven't registered an __objc_imageinfo section yet. Register and
+    // move on. The section should already be marked no-dead-strip.
+    ObjCImageInfos[&MR.getTargetJITDylib()] = std::make_pair(Version, Flags);
+  }
+
+  return Error::success();
+}
+
+} // End namespace orc.
+} // End namespace llvm.