12 files changed, 163 insertions, 160 deletions

diff --git a/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt b/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt
index e5f5a99..65dd0c7 100644
--- a/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt
+++ b/llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt
@@ -3,6 +3,7 @@ tablegen(LLVM COFFOptions.inc -gen-opt-parser-defs)
 add_public_tablegen_target(JITLinkTableGen)
 
 add_llvm_component_library(LLVMJITLink
+  CompactUnwindSupport.cpp
   DWARFRecordSectionSplitter.cpp
   EHFrameSupport.cpp
   JITLink.cpp
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
index 3e757f7..179e458c 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
@@ -733,121 +733,5 @@ Error MachOLinkGraphBuilder::graphifyCStringSection(
   return Error::success();
 }
 
-Error CompactUnwindSplitter::operator()(LinkGraph &G) {
-  auto *CUSec = G.findSectionByName(CompactUnwindSectionName);
-  if (!CUSec)
-    return Error::success();
-
-  if (!G.getTargetTriple().isOSBinFormatMachO())
-    return make_error<JITLinkError>(
-        "Error linking " + G.getName() +
-        ": compact unwind splitting not supported on non-macho target " +
-        G.getTargetTriple().str());
-
-  unsigned CURecordSize = 0;
-  unsigned PersonalityEdgeOffset = 0;
-  unsigned LSDAEdgeOffset = 0;
-  switch (G.getTargetTriple().getArch()) {
-  case Triple::aarch64:
-  case Triple::x86_64:
-    // 64-bit compact-unwind record format:
-    // Range start: 8 bytes.
-    // Range size:  4 bytes.
-    // CU encoding: 4 bytes.
-    // Personality: 8 bytes.
-    // LSDA:        8 bytes.
-    CURecordSize = 32;
-    PersonalityEdgeOffset = 16;
-    LSDAEdgeOffset = 24;
-    break;
-  default:
-    return make_error<JITLinkError>(
-        "Error linking " + G.getName() +
-        ": compact unwind splitting not supported on " +
-        G.getTargetTriple().getArchName());
-  }
-
-  std::vector<Block *> OriginalBlocks(CUSec->blocks().begin(),
-                                      CUSec->blocks().end());
-  LLVM_DEBUG({
-    dbgs() << "In " << G.getName() << " splitting compact unwind section "
-           << CompactUnwindSectionName << " containing "
-           << OriginalBlocks.size() << " initial blocks...\n";
-  });
-
-  while (!OriginalBlocks.empty()) {
-    auto *B = OriginalBlocks.back();
-    OriginalBlocks.pop_back();
-
-    if (B->getSize() == 0) {
-      LLVM_DEBUG({
-        dbgs() << "  Skipping empty block at "
-               << formatv("{0:x16}", B->getAddress()) << "\n";
-      });
-      continue;
-    }
-
-    unsigned NumBlocks = B->getSize() / CURecordSize;
-
-    LLVM_DEBUG({
-      dbgs() << "  Splitting block at " << formatv("{0:x16}", B->getAddress())
-             << " into " << NumBlocks << " compact unwind record(s)\n";
-    });
-
-    if (B->getSize() % CURecordSize)
-      return make_error<JITLinkError>(
-          "Error splitting compact unwind record in " + G.getName() +
-          ": block at " + formatv("{0:x}", B->getAddress()) + " has size " +
-          formatv("{0:x}", B->getSize()) +
-          " (not a multiple of CU record size of " +
-          formatv("{0:x}", CURecordSize) + ")");
-
-    auto Blocks =
-        G.splitBlock(*B, map_range(seq(1U, NumBlocks), [=](Edge::OffsetT Idx) {
-          return Idx * CURecordSize;
-        }));
-
-    for (auto *CURec : Blocks) {
-      bool AddedKeepAlive = false;
-
-      for (auto &E : CURec->edges()) {
-        if (E.getOffset() == 0) {
-          LLVM_DEBUG({
-            dbgs() << "    Updating compact unwind record at "
-                   << CURec->getAddress() << " to point to "
-                   << (E.getTarget().hasName() ? *E.getTarget().getName()
-                                               : StringRef())
-                   << " (at " << E.getTarget().getAddress() << ")\n";
-          });
-
-          if (E.getTarget().isExternal())
-            return make_error<JITLinkError>(
-                "Error adding keep-alive edge for compact unwind record at " +
-                formatv("{0:x}", CURec->getAddress()) + ": target " +
-                *E.getTarget().getName() + " is an external symbol");
-          auto &TgtBlock = E.getTarget().getBlock();
-          auto &CURecSym =
-              G.addAnonymousSymbol(*CURec, 0, CURecordSize, false, false);
-          TgtBlock.addEdge(Edge::KeepAlive, 0, CURecSym, 0);
-          AddedKeepAlive = true;
-        } else if (E.getOffset() != PersonalityEdgeOffset &&
-                   E.getOffset() != LSDAEdgeOffset)
-          return make_error<JITLinkError>(
-              "Unexpected edge at offset " + formatv("{0:x}", E.getOffset()) +
-              " in compact unwind record at " +
-              formatv("{0:x}", CURec->getAddress()));
-      }
-
-      if (!AddedKeepAlive)
-        return make_error<JITLinkError>(
-            "Error adding keep-alive edge for compact unwind record at " +
-            formatv("{0:x}", CURec->getAddress()) +
-            ": no outgoing target edge at offset 0");
-    }
-  }
-
-  return Error::success();
-}
-
 } // end namespace jitlink
 } // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
index 6afa012..343218e 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.h
@@ -236,17 +236,6 @@ private:
   StringMap<SectionParserFunction> CustomSectionParserFunctions;
 };
 
-/// A pass to split up __LD,__compact_unwind sections.
-class CompactUnwindSplitter {
-public:
-  CompactUnwindSplitter(StringRef CompactUnwindSectionName)
-      : CompactUnwindSectionName(CompactUnwindSectionName) {}
-  Error operator()(LinkGraph &G);
-
-private:
-  StringRef CompactUnwindSectionName;
-};
-
 } // end namespace jitlink
 } // end namespace llvm
 
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
index 29061ff..f9f2f4e 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_arm64.cpp
@@ -14,6 +14,7 @@
 #include "llvm/ExecutionEngine/JITLink/DWARFRecordSectionSplitter.h"
 #include "llvm/ExecutionEngine/JITLink/aarch64.h"
 
+#include "CompactUnwindSupport.h"
 #include "DefineExternalSectionStartAndEndSymbols.h"
 #include "MachOLinkGraphBuilder.h"
 
@@ -625,6 +626,27 @@ static Error applyPACSigningToModInitPointers(LinkGraph &G) {
   return Error::success();
 }
 
+struct CompactUnwindTraits_MachO_arm64
+    : public CompactUnwindTraits<CompactUnwindTraits_MachO_arm64,
+                                 /* PointerSize = */ 8> {
+  // FIXME: Reinstate once we no longer need the MSVC workaround. See
+  //        FIXME for CompactUnwindTraits in CompactUnwindSupport.h.
+  // constexpr static size_t PointerSize = 8;
+
+  constexpr static endianness Endianness = endianness::little;
+
+  constexpr static uint32_t EncodingModeMask = 0x0f000000;
+
+  using GOTManager = aarch64::GOTTableManager;
+
+  static bool encodingSpecifiesDWARF(uint32_t Encoding) {
+    constexpr uint32_t DWARFMode = 0x03000000;
+    return (Encoding & EncodingModeMask) == DWARFMode;
+  }
+
+  static bool encodingCannotBeMerged(uint32_t Encoding) { return false; }
+};
+
 void link_MachO_arm64(std::unique_ptr<LinkGraph> G,
                       std::unique_ptr<JITLinkContext> Ctx) {
 
@@ -637,16 +659,21 @@ void link_MachO_arm64(std::unique_ptr<LinkGraph> G,
     else
       Config.PrePrunePasses.push_back(markAllSymbolsLive);
 
-    // Add compact unwind splitter pass.
-    Config.PrePrunePasses.push_back(
-        CompactUnwindSplitter("__LD,__compact_unwind"));
-
     // Add eh-frame passes.
-    // FIXME: Prune eh-frames for which compact-unwind is available once
-    // we support compact-unwind registration with libunwind.
     Config.PrePrunePasses.push_back(createEHFrameSplitterPass_MachO_arm64());
     Config.PrePrunePasses.push_back(createEHFrameEdgeFixerPass_MachO_arm64());
 
+    // Create a compact-unwind manager for use in passes below.
+    auto CompactUnwindMgr =
+        std::make_shared<CompactUnwindManager<CompactUnwindTraits_MachO_arm64>>(
+            "__LD,__compact_unwind", "__TEXT,__unwind_info",
+            "__TEXT,__eh_frame");
+
+    // Add compact unwind prepare pass.
+    Config.PrePrunePasses.push_back([CompactUnwindMgr](LinkGraph &G) {
+      return CompactUnwindMgr->prepareForPrune(G);
+    });
+
     // Resolve any external section start / end symbols.
     Config.PostAllocationPasses.push_back(
         createDefineExternalSectionStartAndEndSymbolsPass(
@@ -663,6 +690,16 @@ void link_MachO_arm64(std::unique_ptr<LinkGraph> G,
       Config.PreFixupPasses.push_back(
           aarch64::lowerPointer64AuthEdgesToSigningFunction);
     }
+
+    // Reserve unwind-info space.
+    Config.PostPrunePasses.push_back([CompactUnwindMgr](LinkGraph &G) {
+      return CompactUnwindMgr->processAndReserveUnwindInfo(G);
+    });
+
+    // Translate compact-unwind to unwind-info.
+    Config.PreFixupPasses.push_back([CompactUnwindMgr](LinkGraph &G) {
+      return CompactUnwindMgr->writeUnwindInfo(G);
+    });
   }
 
   if (auto Err = Ctx->modifyPassConfig(*G, Config))
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
index 9547266..218f8ce 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachO_x86_64.cpp
@@ -14,6 +14,7 @@
 #include "llvm/ExecutionEngine/JITLink/DWARFRecordSectionSplitter.h"
 #include "llvm/ExecutionEngine/JITLink/x86_64.h"
 
+#include "CompactUnwindSupport.h"
 #include "DefineExternalSectionStartAndEndSymbols.h"
 #include "MachOLinkGraphBuilder.h"
 
@@ -500,26 +501,56 @@ Expected<std::unique_ptr<LinkGraph>> createLinkGraphFromMachOObject_x86_64(
       .buildGraph();
 }
 
+struct CompactUnwindTraits_MachO_x86_64
+    : public CompactUnwindTraits<CompactUnwindTraits_MachO_x86_64,
+                                 /* PointerSize = */ 8> {
+  // FIXME: Reinstate once we no longer need the MSVC workaround. See
+  //        FIXME for CompactUnwindTraits in CompactUnwindSupport.h.
+  // constexpr static size_t PointerSize = 8;
+
+  constexpr static endianness Endianness = endianness::little;
+
+  constexpr static uint32_t EncodingModeMask = 0x0f000000;
+
+  using GOTManager = x86_64::GOTTableManager;
+
+  static bool encodingSpecifiesDWARF(uint32_t Encoding) {
+    constexpr uint32_t DWARFMode = 0x04000000;
+    return (Encoding & EncodingModeMask) == DWARFMode;
+  }
+
+  static bool encodingCannotBeMerged(uint32_t Encoding) {
+    constexpr uint32_t StackIndirectMode = 0x03000000;
+    return (Encoding & EncodingModeMask) == StackIndirectMode;
+  }
+};
+
 void link_MachO_x86_64(std::unique_ptr<LinkGraph> G,
                        std::unique_ptr<JITLinkContext> Ctx) {
 
   PassConfiguration Config;
 
   if (Ctx->shouldAddDefaultTargetPasses(G->getTargetTriple())) {
-    // Add eh-frame passes.
-    Config.PrePrunePasses.push_back(createEHFrameSplitterPass_MachO_x86_64());
-    Config.PrePrunePasses.push_back(createEHFrameEdgeFixerPass_MachO_x86_64());
-
-    // Add compact unwind splitter pass.
-    Config.PrePrunePasses.push_back(
-        CompactUnwindSplitter("__LD,__compact_unwind"));
-
     // Add a mark-live pass.
     if (auto MarkLive = Ctx->getMarkLivePass(G->getTargetTriple()))
       Config.PrePrunePasses.push_back(std::move(MarkLive));
     else
       Config.PrePrunePasses.push_back(markAllSymbolsLive);
 
+    // Add eh-frame passes.
+    Config.PrePrunePasses.push_back(createEHFrameSplitterPass_MachO_x86_64());
+    Config.PrePrunePasses.push_back(createEHFrameEdgeFixerPass_MachO_x86_64());
+
+    // Create a compact-unwind manager for use in passes below.
+    auto CompactUnwindMgr = std::make_shared<
+        CompactUnwindManager<CompactUnwindTraits_MachO_x86_64>>(
+        "__LD,__compact_unwind", "__TEXT,__unwind_info", "__TEXT,__eh_frame");
+
+    // Add compact unwind prepare pass.
+    Config.PrePrunePasses.push_back([CompactUnwindMgr](LinkGraph &G) {
+      return CompactUnwindMgr->prepareForPrune(G);
+    });
+
     // Resolve any external section start / end symbols.
     Config.PostAllocationPasses.push_back(
         createDefineExternalSectionStartAndEndSymbolsPass(
@@ -528,6 +559,16 @@ void link_MachO_x86_64(std::unique_ptr<LinkGraph> G,
     // Add an in-place GOT/Stubs pass.
     Config.PostPrunePasses.push_back(buildGOTAndStubs_MachO_x86_64);
 
+    // Reserve space for unwind-info.
+    Config.PostPrunePasses.push_back([CompactUnwindMgr](LinkGraph &G) {
+      return CompactUnwindMgr->processAndReserveUnwindInfo(G);
+    });
+
+    // Translate compact-unwind to unwind-info.
+    Config.PreFixupPasses.push_back([CompactUnwindMgr](LinkGraph &G) {
+      return CompactUnwindMgr->writeUnwindInfo(G);
+    });
+
     // Add GOT/Stubs optimizer pass.
     Config.PreFixupPasses.push_back(x86_64::optimizeGOTAndStubAccesses);
   }
diff --git a/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt b/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt
index 2ab5d6d..8a86629 100644
--- a/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt
+++ b/llvm/lib/ExecutionEngine/Orc/CMakeLists.txt
@@ -57,6 +57,7 @@ add_llvm_component_library(LLVMOrcJIT
   ExecutorProcessControl.cpp
   TaskDispatch.cpp
   ThreadSafeModule.cpp
+  UnwindInfoRegistrationPlugin.cpp
   RedirectionManager.cpp
   JITLinkRedirectableSymbolManager.cpp
   ReOptimizeLayer.cpp
diff --git a/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp b/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp
index 5d2f3cd..c4d65af 100644
--- a/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/CompileUtils.cpp
@@ -33,6 +33,9 @@ irManglingOptionsFromTargetOptions(const TargetOptions &Opts) {
 
 /// Compile a Module to an ObjectFile.
 Expected<SimpleCompiler::CompileResult> SimpleCompiler::operator()(Module &M) {
+  if (M.getDataLayout().isDefault())
+    M.setDataLayout(TM.createDataLayout());
+
   CompileResult CachedObject = tryToLoadFromObjectCache(M);
   if (CachedObject)
     return std::move(CachedObject);
diff --git a/llvm/lib/ExecutionEngine/Orc/Core.cpp b/llvm/lib/ExecutionEngine/Orc/Core.cpp
index d47eb44..9f466e7 100644
--- a/llvm/lib/ExecutionEngine/Orc/Core.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Core.cpp
@@ -1251,9 +1251,7 @@ JITDylib::JITDylib(ExecutionSession &ES, std::string Name)
   LinkOrder.push_back({this, JITDylibLookupFlags::MatchAllSymbols});
 }
 
-std::pair<JITDylib::AsynchronousSymbolQuerySet,
-          std::shared_ptr<SymbolDependenceMap>>
-JITDylib::IL_removeTracker(ResourceTracker &RT) {
+JITDylib::RemoveTrackerResult JITDylib::IL_removeTracker(ResourceTracker &RT) {
   // Note: Should be called under the session lock.
   assert(State != Closed && "JD is defunct");
 
@@ -1292,7 +1290,10 @@ JITDylib::IL_removeTracker(ResourceTracker &RT) {
       SymbolsToFail.push_back(Sym);
   }
 
-  auto Result = ES.IL_failSymbols(*this, std::move(SymbolsToFail));
+  auto [QueriesToFail, FailedSymbols] =
+      ES.IL_failSymbols(*this, std::move(SymbolsToFail));
+
+  std::vector<std::unique_ptr<MaterializationUnit>> DefunctMUs;
 
   // Removed symbols should be taken out of the table altogether.
   for (auto &Sym : SymbolsToRemove) {
@@ -1302,7 +1303,12 @@ JITDylib::IL_removeTracker(ResourceTracker &RT) {
     // Remove Materializer if present.
     if (I->second.hasMaterializerAttached()) {
       // FIXME: Should this discard the symbols?
-      UnmaterializedInfos.erase(Sym);
+      auto J = UnmaterializedInfos.find(Sym);
+      assert(J != UnmaterializedInfos.end() &&
+             "Symbol table indicates MU present, but no UMI record");
+      if (J->second->MU)
+        DefunctMUs.push_back(std::move(J->second->MU));
+      UnmaterializedInfos.erase(J);
     } else {
       assert(!UnmaterializedInfos.count(Sym) &&
              "Symbol has materializer attached");
@@ -1313,7 +1319,8 @@ JITDylib::IL_removeTracker(ResourceTracker &RT) {
 
   shrinkMaterializationInfoMemory();
 
-  return Result;
+  return {std::move(QueriesToFail), std::move(FailedSymbols),
+          std::move(DefunctMUs)};
 }
 
 void JITDylib::transferTracker(ResourceTracker &DstRT, ResourceTracker &SrcRT) {
@@ -2180,16 +2187,17 @@ Error ExecutionSession::removeResourceTracker(ResourceTracker &RT) {
   });
   std::vector<ResourceManager *> CurrentResourceManagers;
 
-  JITDylib::AsynchronousSymbolQuerySet QueriesToFail;
-  std::shared_ptr<SymbolDependenceMap> FailedSymbols;
+  JITDylib::RemoveTrackerResult R;
 
   runSessionLocked([&] {
     CurrentResourceManagers = ResourceManagers;
     RT.makeDefunct();
-    std::tie(QueriesToFail, FailedSymbols) =
-        RT.getJITDylib().IL_removeTracker(RT);
+    R = RT.getJITDylib().IL_removeTracker(RT);
   });
 
+  // Release any defunct MaterializationUnits.
+  R.DefunctMUs.clear();
+
   Error Err = Error::success();
 
   auto &JD = RT.getJITDylib();
@@ -2197,9 +2205,9 @@ Error ExecutionSession::removeResourceTracker(ResourceTracker &RT) {
     Err = joinErrors(std::move(Err),
                      L->handleRemoveResources(JD, RT.getKeyUnsafe()));
 
-  for (auto &Q : QueriesToFail)
-    Q->handleFailed(
-        make_error<FailedToMaterialize>(getSymbolStringPool(), FailedSymbols));
+  for (auto &Q : R.QueriesToFail)
+    Q->handleFailed(make_error<FailedToMaterialize>(getSymbolStringPool(),
+                                                    R.FailedSymbols));
 
   return Err;
 }
diff --git a/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp b/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp
index aa79968..b51fa24b 100644
--- a/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ExecutorProcessControl.cpp
@@ -45,6 +45,7 @@ SelfExecutorProcessControl::SelfExecutorProcessControl(
   this->DylibMgr = this;
   this->JDI = {ExecutorAddr::fromPtr(jitDispatchViaWrapperFunctionManager),
                ExecutorAddr::fromPtr(this)};
+
   if (this->TargetTriple.isOSBinFormatMachO())
     GlobalManglingPrefix = '_';
 
@@ -52,6 +53,12 @@ SelfExecutorProcessControl::SelfExecutorProcessControl(
       ExecutorAddr::fromPtr(&llvm_orc_registerEHFrameSectionWrapper);
   this->BootstrapSymbols[rt::DeregisterEHFrameSectionWrapperName] =
       ExecutorAddr::fromPtr(&llvm_orc_deregisterEHFrameSectionWrapper);
+
+#ifdef __APPLE__
+  this->UnwindInfoMgr = UnwindInfoManager::TryCreate();
+  if (this->UnwindInfoMgr)
+    this->UnwindInfoMgr->addBootstrapSymbols(this->BootstrapSymbols);
+#endif // __APPLE__
 }
 
 Expected<std::unique_ptr<SelfExecutorProcessControl>>
diff --git a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
index 80500d0..ab7f854 100644
--- a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
@@ -21,6 +21,7 @@
 #include "llvm/ExecutionEngine/Orc/ObjectTransformLayer.h"
 #include "llvm/ExecutionEngine/Orc/RTDyldObjectLinkingLayer.h"
 #include "llvm/ExecutionEngine/Orc/TargetProcess/RegisterEHFrames.h"
+#include "llvm/ExecutionEngine/Orc/UnwindInfoRegistrationPlugin.h"
 #include "llvm/ExecutionEngine/SectionMemoryManager.h"
 #include "llvm/IR/GlobalVariable.h"
 #include "llvm/IR/IRBuilder.h"
@@ -1220,12 +1221,28 @@ Expected<JITDylibSP> setUpGenericLLVMIRPlatform(LLJIT &J) {
 
   if (auto *OLL = dyn_cast<ObjectLinkingLayer>(&J.getObjLinkingLayer())) {
 
-    auto &ES = J.getExecutionSession();
-    if (auto EHFrameRegistrar = EPCEHFrameRegistrar::Create(ES))
-      OLL->addPlugin(std::make_unique<EHFrameRegistrationPlugin>(
-          ES, std::move(*EHFrameRegistrar)));
-    else
-      return EHFrameRegistrar.takeError();
+    bool CompactUnwindInfoSupported = false;
+
+    // Enable compact-unwind support if possible.
+    if (J.getTargetTriple().isOSDarwin() ||
+        J.getTargetTriple().isOSBinFormatMachO()) {
+      if (auto UIRP = UnwindInfoRegistrationPlugin::Create(
+              J.getIRCompileLayer(), PlatformJD)) {
+        CompactUnwindInfoSupported = true;
+        OLL->addPlugin(std::move(*UIRP));
+      } else
+        consumeError(UIRP.takeError());
+    }
+
+    // Otherwise fall back to standard unwind registration.
+    if (!CompactUnwindInfoSupported) {
+      auto &ES = J.getExecutionSession();
+      if (auto EHFrameRegistrar = EPCEHFrameRegistrar::Create(ES))
+        OLL->addPlugin(std::make_unique<EHFrameRegistrationPlugin>(
+            ES, std::move(*EHFrameRegistrar)));
+      else
+        return EHFrameRegistrar.takeError();
+    }
   }
 
   J.setPlatformSupport(
diff --git a/llvm/lib/ExecutionEngine/Orc/Shared/OrcRTBridge.cpp b/llvm/lib/ExecutionEngine/Orc/Shared/OrcRTBridge.cpp
index 54a25c0..fef3ff9 100644
--- a/llvm/lib/ExecutionEngine/Orc/Shared/OrcRTBridge.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Shared/OrcRTBridge.cpp
@@ -64,5 +64,19 @@ const char *RunAsIntFunctionWrapperName =
     "__llvm_orc_bootstrap_run_as_int_function_wrapper";
 
 } // end namespace rt
+namespace rt_alt {
+const char *UnwindInfoManagerInstanceName =
+    "orc_rt_alt_UnwindInfoManager_Instance";
+const char *UnwindInfoManagerFindSectionsHelperName =
+    "orc_rt_alt_UnwindInfoManager_findSectionsHelper";
+const char *UnwindInfoManagerEnableWrapperName =
+    "orc_rt_alt_UnwindInfoManager_enable";
+const char *UnwindInfoManagerDisableWrapperName =
+    "orc_rt_alt_UnwindInfoManager_disable";
+const char *UnwindInfoManagerRegisterActionName =
+    "orc_rt_alt_UnwindInfoManager_register";
+const char *UnwindInfoManagerDeregisterActionName =
+    "orc_rt_alt_UnwindInfoManager_deregister";
+} // end namespace rt_alt
 } // end namespace orc
 } // end namespace llvm
diff --git a/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt b/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt
index 3d1dfe7..ffc1bbf 100644
--- a/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt
+++ b/llvm/lib/ExecutionEngine/Orc/TargetProcess/CMakeLists.txt
@@ -20,6 +20,7 @@ add_llvm_component_library(LLVMOrcTargetProcess
   SimpleExecutorMemoryManager.cpp
   SimpleRemoteEPCServer.cpp
   TargetExecutionUtils.cpp
+  UnwindInfoManager.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/ExecutionEngine/Orc