vendor/llvm-project/llvmorg-18-init-15088-gd14ee76181fb

19 files changed, 222 insertions, 208 deletions

diff --git a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
index 46f8064bb168..a1fe9c5fcd73 100644
--- a/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/ELF_x86_64.cpp
@@ -349,11 +349,11 @@ identifyELFSectionStartAndEndSymbols(LinkGraph &G, Symbol &Sym) {
   constexpr StringRef EndSymbolPrefix = "__end";
 
   auto SymName = Sym.getName();
-  if (SymName.startswith(StartSymbolPrefix)) {
+  if (SymName.starts_with(StartSymbolPrefix)) {
     if (auto *Sec =
             G.findSectionByName(SymName.drop_front(StartSymbolPrefix.size())))
       return {*Sec, true};
-  } else if (SymName.startswith(EndSymbolPrefix)) {
+  } else if (SymName.starts_with(EndSymbolPrefix)) {
     if (auto *Sec =
             G.findSectionByName(SymName.drop_front(EndSymbolPrefix.size())))
       return {*Sec, false};
diff --git a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
index bcbc429cae12..bb21f633d982 100644
--- a/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
+++ b/llvm/lib/ExecutionEngine/JITLink/MachOLinkGraphBuilder.cpp
@@ -73,7 +73,7 @@ Linkage MachOLinkGraphBuilder::getLinkage(uint16_t Desc) {
 
 Scope MachOLinkGraphBuilder::getScope(StringRef Name, uint8_t Type) {
   if (Type & MachO::N_EXT) {
-    if ((Type & MachO::N_PEXT) || Name.startswith("l"))
+    if ((Type & MachO::N_PEXT) || Name.starts_with("l"))
       return Scope::Hidden;
     else
       return Scope::Default;
diff --git a/llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp b/llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp
index b541db3672f4..f65ec27ff875 100644
--- a/llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Debugging/DebugInfoSupport.cpp
@@ -105,7 +105,7 @@ llvm::orc::createDWARFContext(LinkGraph &G) {
       auto SecData = getSectionData(Sec);
       auto Name = Sec.getName();
       // DWARFContext expects the section name to not start with a dot
-      if (Name.startswith("."))
+      if (Name.starts_with("."))
         Name = Name.drop_front();
       LLVM_DEBUG(dbgs() << "Creating DWARFContext section " << Name
                         << " with size " << SecData.size() << "\n");
diff --git a/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupport.cpp b/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupport.cpp
index 9ba6dd90f50d..1668473c0eb4 100644
--- a/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupport.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupport.cpp
@@ -39,7 +39,7 @@ Error enableDebuggerSupport(LLJIT &J) {
     if (!Registrar)
       return Registrar.takeError();
     ObjLinkingLayer->addPlugin(std::make_unique<DebugObjectManagerPlugin>(
-        ES, std::move(*Registrar), true, true));
+        ES, std::move(*Registrar), false, true));
     return Error::success();
   }
   case Triple::MachO: {
diff --git a/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupportPlugin.cpp b/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupportPlugin.cpp
index c6ffd9f7c2e3..e387b06ee934 100644
--- a/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupportPlugin.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Debugging/DebuggerSupportPlugin.cpp
@@ -34,7 +34,7 @@ class MachODebugObjectSynthesizerBase
     : public GDBJITDebugInfoRegistrationPlugin::DebugSectionSynthesizer {
 public:
   static bool isDebugSection(Section &Sec) {
-    return Sec.getName().startswith("__DWARF,");
+    return Sec.getName().starts_with("__DWARF,");
   }
 
   MachODebugObjectSynthesizerBase(LinkGraph &G, ExecutorAddr RegisterActionAddr)
diff --git a/llvm/lib/ExecutionEngine/Orc/Debugging/LLJITUtilsCBindings.cpp b/llvm/lib/ExecutionEngine/Orc/Debugging/LLJITUtilsCBindings.cpp
new file mode 100644
index 000000000000..2df5aef733fb
--- /dev/null
+++ b/llvm/lib/ExecutionEngine/Orc/Debugging/LLJITUtilsCBindings.cpp
@@ -0,0 +1,22 @@
+//===--------- LLJITUtilsCBindings.cpp - Advanced LLJIT features ----------===//
+//
+// 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-c/LLJIT.h"
+#include "llvm-c/LLJITUtils.h"
+
+#include "llvm/ExecutionEngine/Orc/Debugging/DebuggerSupport.h"
+#include "llvm/ExecutionEngine/Orc/LLJIT.h"
+
+using namespace llvm;
+using namespace llvm::orc;
+
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLJIT, LLVMOrcLLJITRef)
+
+LLVMErrorRef LLVMOrcLLJITEnableDebugSupport(LLVMOrcLLJITRef J) {
+  return wrap(llvm::orc::enableDebuggerSupport(*unwrap(J)));
+}
diff --git a/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
index 7316b2dce8ab..8d5608cc4d4c 100644
--- a/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ExecutionUtils.cpp
@@ -103,8 +103,8 @@ bool StaticInitGVIterator::isStaticInitGlobal(GlobalValue &GV) {
     // FIXME: These section checks are too strict: We should match first and
     // second word split by comma.
     if (GV.hasSection() &&
-        (GV.getSection().startswith("__DATA,__objc_classlist") ||
-         GV.getSection().startswith("__DATA,__objc_selrefs")))
+        (GV.getSection().starts_with("__DATA,__objc_classlist") ||
+         GV.getSection().starts_with("__DATA,__objc_selrefs")))
       return true;
   }
 
@@ -503,7 +503,7 @@ Error DLLImportDefinitionGenerator::tryToGenerate(
   DenseMap<StringRef, SymbolLookupFlags> ToLookUpSymbols;
   for (auto &KV : Symbols) {
     StringRef Deinterned = *KV.first;
-    if (Deinterned.startswith(getImpPrefix()))
+    if (Deinterned.starts_with(getImpPrefix()))
       Deinterned = Deinterned.drop_front(StringRef(getImpPrefix()).size());
     // Don't degrade the required state
     if (ToLookUpSymbols.count(Deinterned) &&
diff --git a/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp b/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp
index adf38659de3d..f9efff148df9 100644
--- a/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/IndirectionUtils.cpp
@@ -285,7 +285,7 @@ std::vector<GlobalValue *> SymbolLinkagePromoter::operator()(Module &M) {
     // Rename if necessary.
     if (!GV.hasName())
       GV.setName("__orc_anon." + Twine(NextId++));
-    else if (GV.getName().startswith("\01L"))
+    else if (GV.getName().starts_with("\01L"))
       GV.setName("__" + GV.getName().substr(1) + "." + Twine(NextId++));
     else if (GV.hasLocalLinkage())
       GV.setName("__orc_lcl." + GV.getName() + "." + Twine(NextId++));
diff --git a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
index 90123b3f0a96..a19e17029810 100644
--- a/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/LLJIT.cpp
@@ -84,65 +84,6 @@ Function *addHelperAndWrapper(Module &M, StringRef WrapperName,
   return WrapperFn;
 }
 
-class ORCPlatformSupport : public LLJIT::PlatformSupport {
-public:
-  ORCPlatformSupport(orc::LLJIT &J) : J(J) {}
-
-  Error initialize(orc::JITDylib &JD) override {
-    using llvm::orc::shared::SPSExecutorAddr;
-    using llvm::orc::shared::SPSString;
-    using SPSDLOpenSig = SPSExecutorAddr(SPSString, int32_t);
-    enum dlopen_mode : int32_t {
-      ORC_RT_RTLD_LAZY = 0x1,
-      ORC_RT_RTLD_NOW = 0x2,
-      ORC_RT_RTLD_LOCAL = 0x4,
-      ORC_RT_RTLD_GLOBAL = 0x8
-    };
-
-    auto &ES = J.getExecutionSession();
-    auto MainSearchOrder = J.getMainJITDylib().withLinkOrderDo(
-        [](const JITDylibSearchOrder &SO) { return SO; });
-
-    if (auto WrapperAddr =
-            ES.lookup(MainSearchOrder,
-                      J.mangleAndIntern("__orc_rt_jit_dlopen_wrapper"))) {
-      return ES.callSPSWrapper<SPSDLOpenSig>(WrapperAddr->getAddress(),
-                                             DSOHandles[&JD], JD.getName(),
-                                             int32_t(ORC_RT_RTLD_LAZY));
-    } else
-      return WrapperAddr.takeError();
-  }
-
-  Error deinitialize(orc::JITDylib &JD) override {
-    using llvm::orc::shared::SPSExecutorAddr;
-    using SPSDLCloseSig = int32_t(SPSExecutorAddr);
-
-    auto &ES = J.getExecutionSession();
-    auto MainSearchOrder = J.getMainJITDylib().withLinkOrderDo(
-        [](const JITDylibSearchOrder &SO) { return SO; });
-
-    if (auto WrapperAddr =
-            ES.lookup(MainSearchOrder,
-                      J.mangleAndIntern("__orc_rt_jit_dlclose_wrapper"))) {
-      int32_t result;
-      auto E = J.getExecutionSession().callSPSWrapper<SPSDLCloseSig>(
-          WrapperAddr->getAddress(), result, DSOHandles[&JD]);
-      if (E)
-        return E;
-      else if (result)
-        return make_error<StringError>("dlclose failed",
-                                       inconvertibleErrorCode());
-      DSOHandles.erase(&JD);
-    } else
-      return WrapperAddr.takeError();
-    return Error::success();
-  }
-
-private:
-  orc::LLJIT &J;
-  DenseMap<orc::JITDylib *, orc::ExecutorAddr> DSOHandles;
-};
-
 class GenericLLVMIRPlatformSupport;
 
 /// orc::Platform component of Generic LLVM IR Platform support.
@@ -272,11 +213,11 @@ public:
       // will trigger a lookup to materialize the module) and the InitFunctions
       // map (which holds the names of the symbols to execute).
       for (auto &KV : MU.getSymbols())
-        if ((*KV.first).startswith(InitFunctionPrefix)) {
+        if ((*KV.first).starts_with(InitFunctionPrefix)) {
           InitSymbols[&JD].add(KV.first,
                                SymbolLookupFlags::WeaklyReferencedSymbol);
           InitFunctions[&JD].add(KV.first);
-        } else if ((*KV.first).startswith(DeInitFunctionPrefix)) {
+        } else if ((*KV.first).starts_with(DeInitFunctionPrefix)) {
           DeInitFunctions[&JD].add(KV.first);
         }
     }
@@ -656,6 +597,54 @@ public:
 namespace llvm {
 namespace orc {
 
+Error ORCPlatformSupport::initialize(orc::JITDylib &JD) {
+  using llvm::orc::shared::SPSExecutorAddr;
+  using llvm::orc::shared::SPSString;
+  using SPSDLOpenSig = SPSExecutorAddr(SPSString, int32_t);
+  enum dlopen_mode : int32_t {
+    ORC_RT_RTLD_LAZY = 0x1,
+    ORC_RT_RTLD_NOW = 0x2,
+    ORC_RT_RTLD_LOCAL = 0x4,
+    ORC_RT_RTLD_GLOBAL = 0x8
+  };
+
+  auto &ES = J.getExecutionSession();
+  auto MainSearchOrder = J.getMainJITDylib().withLinkOrderDo(
+      [](const JITDylibSearchOrder &SO) { return SO; });
+
+  if (auto WrapperAddr = ES.lookup(
+          MainSearchOrder, J.mangleAndIntern("__orc_rt_jit_dlopen_wrapper"))) {
+    return ES.callSPSWrapper<SPSDLOpenSig>(WrapperAddr->getAddress(),
+                                           DSOHandles[&JD], JD.getName(),
+                                           int32_t(ORC_RT_RTLD_LAZY));
+  } else
+    return WrapperAddr.takeError();
+}
+
+Error ORCPlatformSupport::deinitialize(orc::JITDylib &JD) {
+  using llvm::orc::shared::SPSExecutorAddr;
+  using SPSDLCloseSig = int32_t(SPSExecutorAddr);
+
+  auto &ES = J.getExecutionSession();
+  auto MainSearchOrder = J.getMainJITDylib().withLinkOrderDo(
+      [](const JITDylibSearchOrder &SO) { return SO; });
+
+  if (auto WrapperAddr = ES.lookup(
+          MainSearchOrder, J.mangleAndIntern("__orc_rt_jit_dlclose_wrapper"))) {
+    int32_t result;
+    auto E = J.getExecutionSession().callSPSWrapper<SPSDLCloseSig>(
+        WrapperAddr->getAddress(), result, DSOHandles[&JD]);
+    if (E)
+      return E;
+    else if (result)
+      return make_error<StringError>("dlclose failed",
+                                     inconvertibleErrorCode());
+    DSOHandles.erase(&JD);
+  } else
+    return WrapperAddr.takeError();
+  return Error::success();
+}
+
 void LLJIT::PlatformSupport::setInitTransform(
     LLJIT &J, IRTransformLayer::TransformFunction T) {
   J.InitHelperTransformLayer->setTransform(std::move(T));
diff --git a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
index a155b39ae263..9057300bf043 100644
--- a/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/MachOPlatform.cpp
@@ -15,6 +15,7 @@
 #include "llvm/ExecutionEngine/Orc/DebugUtils.h"
 #include "llvm/ExecutionEngine/Orc/ExecutionUtils.h"
 #include "llvm/ExecutionEngine/Orc/LookupAndRecordAddrs.h"
+#include "llvm/ExecutionEngine/Orc/MachOBuilder.h"
 #include "llvm/ExecutionEngine/Orc/Shared/ObjectFormats.h"
 #include "llvm/Support/BinaryByteStream.h"
 #include "llvm/Support/Debug.h"
@@ -115,100 +116,6 @@ std::unique_ptr<jitlink::LinkGraph> createPlatformGraph(MachOPlatform &MOP,
                                               jitlink::getGenericEdgeKindName);
 }
 
-// Generates a MachO header.
-class MachOHeaderMaterializationUnit : public MaterializationUnit {
-public:
-  MachOHeaderMaterializationUnit(MachOPlatform &MOP,
-                                 const SymbolStringPtr &HeaderStartSymbol)
-      : MaterializationUnit(createHeaderInterface(MOP, HeaderStartSymbol)),
-        MOP(MOP) {}
-
-  StringRef getName() const override { return "MachOHeaderMU"; }
-
-  void materialize(std::unique_ptr<MaterializationResponsibility> R) override {
-    auto G = createPlatformGraph(MOP, "<MachOHeaderMU>");
-    addMachOHeader(*G, MOP, R->getInitializerSymbol());
-    MOP.getObjectLinkingLayer().emit(std::move(R), std::move(G));
-  }
-
-  void discard(const JITDylib &JD, const SymbolStringPtr &Sym) override {}
-
-  static void addMachOHeader(jitlink::LinkGraph &G, MachOPlatform &MOP,
-                             const SymbolStringPtr &InitializerSymbol) {
-    auto &HeaderSection = G.createSection("__header", MemProt::Read);
-    auto &HeaderBlock = createHeaderBlock(G, HeaderSection);
-
-    // Init symbol is header-start symbol.
-    G.addDefinedSymbol(HeaderBlock, 0, *InitializerSymbol,
-                       HeaderBlock.getSize(), jitlink::Linkage::Strong,
-                       jitlink::Scope::Default, false, true);
-    for (auto &HS : AdditionalHeaderSymbols)
-      G.addDefinedSymbol(HeaderBlock, HS.Offset, HS.Name, HeaderBlock.getSize(),
-                         jitlink::Linkage::Strong, jitlink::Scope::Default,
-                         false, true);
-  }
-
-private:
-  struct HeaderSymbol {
-    const char *Name;
-    uint64_t Offset;
-  };
-
-  static constexpr HeaderSymbol AdditionalHeaderSymbols[] = {
-      {"___mh_executable_header", 0}};
-
-  static jitlink::Block &createHeaderBlock(jitlink::LinkGraph &G,
-                                           jitlink::Section &HeaderSection) {
-    MachO::mach_header_64 Hdr;
-    Hdr.magic = MachO::MH_MAGIC_64;
-    switch (G.getTargetTriple().getArch()) {
-    case Triple::aarch64:
-      Hdr.cputype = MachO::CPU_TYPE_ARM64;
-      Hdr.cpusubtype = MachO::CPU_SUBTYPE_ARM64_ALL;
-      break;
-    case Triple::x86_64:
-      Hdr.cputype = MachO::CPU_TYPE_X86_64;
-      Hdr.cpusubtype = MachO::CPU_SUBTYPE_X86_64_ALL;
-      break;
-    default:
-      llvm_unreachable("Unrecognized architecture");
-    }
-    Hdr.filetype = MachO::MH_DYLIB; // Custom file type?
-    Hdr.ncmds = 0;
-    Hdr.sizeofcmds = 0;
-    Hdr.flags = 0;
-    Hdr.reserved = 0;
-
-    if (G.getEndianness() != llvm::endianness::native)
-      MachO::swapStruct(Hdr);
-
-    auto HeaderContent = G.allocateContent(
-        ArrayRef<char>(reinterpret_cast<const char *>(&Hdr), sizeof(Hdr)));
-
-    return G.createContentBlock(HeaderSection, HeaderContent, ExecutorAddr(), 8,
-                                0);
-  }
-
-  static MaterializationUnit::Interface
-  createHeaderInterface(MachOPlatform &MOP,
-                        const SymbolStringPtr &HeaderStartSymbol) {
-    SymbolFlagsMap HeaderSymbolFlags;
-
-    HeaderSymbolFlags[HeaderStartSymbol] = JITSymbolFlags::Exported;
-    for (auto &HS : AdditionalHeaderSymbols)
-      HeaderSymbolFlags[MOP.getExecutionSession().intern(HS.Name)] =
-          JITSymbolFlags::Exported;
-
-    return MaterializationUnit::Interface(std::move(HeaderSymbolFlags),
-                                          HeaderStartSymbol);
-  }
-
-  MachOPlatform &MOP;
-};
-
-constexpr MachOHeaderMaterializationUnit::HeaderSymbol
-    MachOHeaderMaterializationUnit::AdditionalHeaderSymbols[];
-
 // Creates a Bootstrap-Complete LinkGraph to run deferred actions.
 class MachOPlatformCompleteBootstrapMaterializationUnit
     : public MaterializationUnit {
@@ -352,6 +259,7 @@ Expected<std::unique_ptr<MachOPlatform>>
 MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
                       JITDylib &PlatformJD,
                       std::unique_ptr<DefinitionGenerator> OrcRuntime,
+                      MachOHeaderMUBuilder BuildMachOHeaderMU,
                       std::optional<SymbolAliasMap> RuntimeAliases) {
 
   // If the target is not supported then bail out immediately.
@@ -382,8 +290,9 @@ MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
 
   // Create the instance.
   Error Err = Error::success();
-  auto P = std::unique_ptr<MachOPlatform>(new MachOPlatform(
-      ES, ObjLinkingLayer, PlatformJD, std::move(OrcRuntime), Err));
+  auto P = std::unique_ptr<MachOPlatform>(
+      new MachOPlatform(ES, ObjLinkingLayer, PlatformJD, std::move(OrcRuntime),
+                        std::move(BuildMachOHeaderMU), Err));
   if (Err)
     return std::move(Err);
   return std::move(P);
@@ -392,6 +301,7 @@ MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
 Expected<std::unique_ptr<MachOPlatform>>
 MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
                       JITDylib &PlatformJD, const char *OrcRuntimePath,
+                      MachOHeaderMUBuilder BuildMachOHeaderMU,
                       std::optional<SymbolAliasMap> RuntimeAliases) {
 
   // Create a generator for the ORC runtime archive.
@@ -402,12 +312,11 @@ MachOPlatform::Create(ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
 
   return Create(ES, ObjLinkingLayer, PlatformJD,
                 std::move(*OrcRuntimeArchiveGenerator),
-                std::move(RuntimeAliases));
+                std::move(BuildMachOHeaderMU), std::move(RuntimeAliases));
 }
 
 Error MachOPlatform::setupJITDylib(JITDylib &JD) {
-  if (auto Err = JD.define(std::make_unique<MachOHeaderMaterializationUnit>(
-          *this, MachOHeaderStartSymbol)))
+  if (auto Err = JD.define(BuildMachOHeaderMU(*this)))
     return Err;
 
   return ES.lookup({&JD}, MachOHeaderStartSymbol).takeError();
@@ -522,8 +431,10 @@ MachOPlatform::flagsForSymbol(jitlink::Symbol &Sym) {
 MachOPlatform::MachOPlatform(
     ExecutionSession &ES, ObjectLinkingLayer &ObjLinkingLayer,
     JITDylib &PlatformJD,
-    std::unique_ptr<DefinitionGenerator> OrcRuntimeGenerator, Error &Err)
-    : ES(ES), PlatformJD(PlatformJD), ObjLinkingLayer(ObjLinkingLayer) {
+    std::unique_ptr<DefinitionGenerator> OrcRuntimeGenerator,
+    MachOHeaderMUBuilder BuildMachOHeaderMU, Error &Err)
+    : ES(ES), PlatformJD(PlatformJD), ObjLinkingLayer(ObjLinkingLayer),
+      BuildMachOHeaderMU(std::move(BuildMachOHeaderMU)) {
   ErrorAsOutParameter _(&Err);
   ObjLinkingLayer.addPlugin(std::make_unique<MachOPlatformPlugin>(*this));
   PlatformJD.addGenerator(std::move(OrcRuntimeGenerator));
@@ -586,8 +497,7 @@ MachOPlatform::MachOPlatform(
   //    the support methods callable. The bootstrap is now complete.
 
   // Step (1) Add header materialization unit and request.
-  if ((Err = PlatformJD.define(std::make_unique<MachOHeaderMaterializationUnit>(
-           *this, MachOHeaderStartSymbol))))
+  if ((Err = PlatformJD.define(this->BuildMachOHeaderMU(*this))))
     return;
   if ((Err = ES.lookup(&PlatformJD, MachOHeaderStartSymbol).takeError()))
     return;
@@ -1755,5 +1665,97 @@ Error MachOPlatform::MachOPlatformPlugin::addSymbolTableRegistration(
 
   return Error::success();
 }
+
+template <typename MachOTraits>
+jitlink::Block &createTrivialHeaderBlock(MachOPlatform &MOP,
+                                         jitlink::LinkGraph &G,
+                                         jitlink::Section &HeaderSection) {
+  auto HdrInfo =
+      getMachOHeaderInfoFromTriple(MOP.getExecutionSession().getTargetTriple());
+  MachOBuilder<MachOTraits> B(HdrInfo.PageSize);
+
+  B.Header.filetype = MachO::MH_DYLIB;
+  B.Header.cputype = HdrInfo.CPUType;
+  B.Header.cpusubtype = HdrInfo.CPUSubType;
+
+  auto HeaderContent = G.allocateBuffer(B.layout());
+  B.write(HeaderContent);
+
+  return G.createContentBlock(HeaderSection, HeaderContent, ExecutorAddr(), 8,
+                              0);
+}
+
+SimpleMachOHeaderMU::SimpleMachOHeaderMU(MachOPlatform &MOP,
+                                         SymbolStringPtr HeaderStartSymbol)
+    : MaterializationUnit(
+          createHeaderInterface(MOP, std::move(HeaderStartSymbol))),
+      MOP(MOP) {}
+
+void SimpleMachOHeaderMU::materialize(
+    std::unique_ptr<MaterializationResponsibility> R) {
+  auto G = createPlatformGraph(MOP, "<MachOHeaderMU>");
+  addMachOHeader(R->getTargetJITDylib(), *G, R->getInitializerSymbol());
+  MOP.getObjectLinkingLayer().emit(std::move(R), std::move(G));
+}
+
+void SimpleMachOHeaderMU::discard(const JITDylib &JD,
+                                  const SymbolStringPtr &Sym) {}
+
+void SimpleMachOHeaderMU::addMachOHeader(
+    JITDylib &JD, jitlink::LinkGraph &G,
+    const SymbolStringPtr &InitializerSymbol) {
+  auto &HeaderSection = G.createSection("__header", MemProt::Read);
+  auto &HeaderBlock = createHeaderBlock(JD, G, HeaderSection);
+
+  // Init symbol is header-start symbol.
+  G.addDefinedSymbol(HeaderBlock, 0, *InitializerSymbol, HeaderBlock.getSize(),
+                     jitlink::Linkage::Strong, jitlink::Scope::Default, false,
+                     true);
+  for (auto &HS : AdditionalHeaderSymbols)
+    G.addDefinedSymbol(HeaderBlock, HS.Offset, HS.Name, HeaderBlock.getSize(),
+                       jitlink::Linkage::Strong, jitlink::Scope::Default, false,
+                       true);
+}
+
+jitlink::Block &
+SimpleMachOHeaderMU::createHeaderBlock(JITDylib &JD, jitlink::LinkGraph &G,
+                                       jitlink::Section &HeaderSection) {
+  switch (MOP.getExecutionSession().getTargetTriple().getArch()) {
+  case Triple::aarch64:
+  case Triple::x86_64:
+    return createTrivialHeaderBlock<MachO64LE>(MOP, G, HeaderSection);
+  default:
+    llvm_unreachable("Unsupported architecture");
+  }
+}
+
+MaterializationUnit::Interface SimpleMachOHeaderMU::createHeaderInterface(
+    MachOPlatform &MOP, const SymbolStringPtr &HeaderStartSymbol) {
+  SymbolFlagsMap HeaderSymbolFlags;
+
+  HeaderSymbolFlags[HeaderStartSymbol] = JITSymbolFlags::Exported;
+  for (auto &HS : AdditionalHeaderSymbols)
+    HeaderSymbolFlags[MOP.getExecutionSession().intern(HS.Name)] =
+        JITSymbolFlags::Exported;
+
+  return MaterializationUnit::Interface(std::move(HeaderSymbolFlags),
+                                        HeaderStartSymbol);
+}
+
+MachOHeaderInfo getMachOHeaderInfoFromTriple(const Triple &TT) {
+  switch (TT.getArch()) {
+  case Triple::aarch64:
+    return {/* PageSize   = */ 16 * 1024,
+            /* CPUType    = */ MachO::CPU_TYPE_ARM64,
+            /* CPUSubType = */ MachO::CPU_SUBTYPE_ARM64_ALL};
+  case Triple::x86_64:
+    return {/* PageSize   = */ 4 * 1024,
+            /* CPUType    = */ MachO::CPU_TYPE_X86_64,
+            /* CPUSubType = */ MachO::CPU_SUBTYPE_X86_64_ALL};
+  default:
+    llvm_unreachable("Unrecognized architecture");
+  }
+}
+
 } // End namespace orc.
 } // End namespace llvm.
diff --git a/llvm/lib/ExecutionEngine/Orc/ObjectFileInterface.cpp b/llvm/lib/ExecutionEngine/Orc/ObjectFileInterface.cpp
index 7c8fa63477d0..0286b0c93197 100644
--- a/llvm/lib/ExecutionEngine/Orc/ObjectFileInterface.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/ObjectFileInterface.cpp
@@ -72,7 +72,7 @@ getMachOObjectFileSymbolInfo(ExecutionSession &ES,
       return SymFlags.takeError();
 
     // Strip the 'exported' flag from MachO linker-private symbols.
-    if (Name->startswith("l"))
+    if (Name->starts_with("l"))
       *SymFlags &= ~JITSymbolFlags::Exported;
 
     I.SymbolFlags[ES.intern(*Name)] = std::move(*SymFlags);
diff --git a/llvm/lib/ExecutionEngine/Orc/Shared/ObjectFormats.cpp b/llvm/lib/ExecutionEngine/Orc/Shared/ObjectFormats.cpp
index 1d9d23e64158..a407fcab6ae3 100644
--- a/llvm/lib/ExecutionEngine/Orc/Shared/ObjectFormats.cpp
+++ b/llvm/lib/ExecutionEngine/Orc/Shared/ObjectFormats.cpp
@@ -102,7 +102,7 @@ bool isELFInitializerSection(StringRef SecName) {
 }
 
 bool isCOFFInitializerSection(StringRef SecName) {
-  return SecName.startswith(".CRT");
+  return SecName.starts_with(".CRT");
 }
 
 } // namespace orc
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/JITSymbol.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/JITSymbol.cpp
index 210fbf6e43e3..c153b4464568 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/JITSymbol.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/JITSymbol.cpp
@@ -42,7 +42,7 @@ JITSymbolFlags llvm::JITSymbolFlags::fromGlobalValue(const GlobalValue &GV) {
     const auto &DL = M->getDataLayout();
     StringRef LPGP = DL.getLinkerPrivateGlobalPrefix();
     if (!LPGP.empty() && GV.getName().front() == '\01' &&
-        GV.getName().substr(1).startswith(LPGP))
+        GV.getName().substr(1).starts_with(LPGP))
       Flags &= ~JITSymbolFlags::Exported;
   }
 
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldCOFF.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldCOFF.cpp
index 9255311f992d..25a2d8780fb5 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldCOFF.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldCOFF.cpp
@@ -83,7 +83,8 @@ uint64_t RuntimeDyldCOFF::getDLLImportOffset(unsigned SectionID, StubMap &Stubs,
                                              StringRef Name,
                                              bool SetSectionIDMinus1) {
   LLVM_DEBUG(dbgs() << "Getting DLLImport entry for " << Name << "... ");
-  assert(Name.startswith(getImportSymbolPrefix()) && "Not a DLLImport symbol?");
+  assert(Name.starts_with(getImportSymbolPrefix()) &&
+         "Not a DLLImport symbol?");
   RelocationValueRef Reloc;
   Reloc.SymbolName = Name.data();
   auto I = Stubs.find(Reloc);
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
index 68497305f06b..7fadbdd6a1ff 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/RuntimeDyldChecker.cpp
@@ -142,7 +142,7 @@ private:
       std::tie(Token, Remaining) = parseNumberString(Expr);
     else {
       unsigned TokLen = 1;
-      if (Expr.startswith("<<") || Expr.startswith(">>"))
+      if (Expr.starts_with("<<") || Expr.starts_with(">>"))
         TokLen = 2;
       Token = Expr.substr(0, TokLen);
     }
@@ -177,9 +177,9 @@ private:
       return std::make_pair(BinOpToken::Invalid, "");
 
     // Handle the two 2-character tokens.
-    if (Expr.startswith("<<"))
+    if (Expr.starts_with("<<"))
       return std::make_pair(BinOpToken::ShiftLeft, Expr.substr(2).ltrim());
-    if (Expr.startswith(">>"))
+    if (Expr.starts_with(">>"))
       return std::make_pair(BinOpToken::ShiftRight, Expr.substr(2).ltrim());
 
     // Handle one-character tokens.
@@ -242,7 +242,7 @@ private:
   // On success, returns a pair containing the value of the operand, plus
   // the expression remaining to be evaluated.
   std::pair<EvalResult, StringRef> evalDecodeOperand(StringRef Expr) const {
-    if (!Expr.startswith("("))
+    if (!Expr.starts_with("("))
       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
     StringRef RemainingExpr = Expr.substr(1).ltrim();
     StringRef Symbol;
@@ -273,7 +273,7 @@ private:
           "");
     }
 
-    if (!RemainingExpr.startswith(","))
+    if (!RemainingExpr.starts_with(","))
       return std::make_pair(
           unexpectedToken(RemainingExpr, RemainingExpr, "expected ','"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -283,7 +283,7 @@ private:
     if (OpIdxExpr.hasError())
       return std::make_pair(OpIdxExpr, "");
 
-    if (!RemainingExpr.startswith(")"))
+    if (!RemainingExpr.starts_with(")"))
       return std::make_pair(
           unexpectedToken(RemainingExpr, RemainingExpr, "expected ')'"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -343,7 +343,7 @@ private:
   // expression remaining to be evaluated.
   std::pair<EvalResult, StringRef> evalNextPC(StringRef Expr,
                                               ParseContext PCtx) const {
-    if (!Expr.startswith("("))
+    if (!Expr.starts_with("("))
       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
     StringRef RemainingExpr = Expr.substr(1).ltrim();
     StringRef Symbol;
@@ -354,7 +354,7 @@ private:
           EvalResult(("Cannot decode unknown symbol '" + Symbol + "'").str()),
           "");
 
-    if (!RemainingExpr.startswith(")"))
+    if (!RemainingExpr.starts_with(")"))
       return std::make_pair(
           unexpectedToken(RemainingExpr, RemainingExpr, "expected ')'"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -381,7 +381,7 @@ private:
   // remaining to be evaluated.
   std::pair<EvalResult, StringRef>
   evalStubOrGOTAddr(StringRef Expr, ParseContext PCtx, bool IsStubAddr) const {
-    if (!Expr.startswith("("))
+    if (!Expr.starts_with("("))
       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
     StringRef RemainingExpr = Expr.substr(1).ltrim();
 
@@ -392,7 +392,7 @@ private:
     StubContainerName = RemainingExpr.substr(0, ComaIdx).rtrim();
     RemainingExpr = RemainingExpr.substr(ComaIdx).ltrim();
 
-    if (!RemainingExpr.startswith(","))
+    if (!RemainingExpr.starts_with(","))
       return std::make_pair(
           unexpectedToken(RemainingExpr, Expr, "expected ','"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -400,7 +400,7 @@ private:
     StringRef Symbol;
     std::tie(Symbol, RemainingExpr) = parseSymbol(RemainingExpr);
 
-    if (!RemainingExpr.startswith(")"))
+    if (!RemainingExpr.starts_with(")"))
       return std::make_pair(
           unexpectedToken(RemainingExpr, Expr, "expected ')'"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -418,7 +418,7 @@ private:
 
   std::pair<EvalResult, StringRef> evalSectionAddr(StringRef Expr,
                                                    ParseContext PCtx) const {
-    if (!Expr.startswith("("))
+    if (!Expr.starts_with("("))
       return std::make_pair(unexpectedToken(Expr, Expr, "expected '('"), "");
     StringRef RemainingExpr = Expr.substr(1).ltrim();
 
@@ -429,7 +429,7 @@ private:
     FileName = RemainingExpr.substr(0, ComaIdx).rtrim();
     RemainingExpr = RemainingExpr.substr(ComaIdx).ltrim();
 
-    if (!RemainingExpr.startswith(","))
+    if (!RemainingExpr.starts_with(","))
       return std::make_pair(
           unexpectedToken(RemainingExpr, Expr, "expected ','"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -439,7 +439,7 @@ private:
     SectionName = RemainingExpr.substr(0, CloseParensIdx).rtrim();
     RemainingExpr = RemainingExpr.substr(CloseParensIdx).ltrim();
 
-    if (!RemainingExpr.startswith(")"))
+    if (!RemainingExpr.starts_with(")"))
       return std::make_pair(
           unexpectedToken(RemainingExpr, Expr, "expected ')'"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -480,7 +480,7 @@ private:
       std::string ErrMsg("No known address for symbol '");
       ErrMsg += Symbol;
       ErrMsg += "'";
-      if (Symbol.startswith("L"))
+      if (Symbol.starts_with("L"))
         ErrMsg += " (this appears to be an assembler local label - "
                   " perhaps drop the 'L'?)";
 
@@ -501,7 +501,7 @@ private:
   // pair representing the number and the expression remaining to be parsed.
   std::pair<StringRef, StringRef> parseNumberString(StringRef Expr) const {
     size_t FirstNonDigit = StringRef::npos;
-    if (Expr.startswith("0x")) {
+    if (Expr.starts_with("0x")) {
       FirstNonDigit = Expr.find_first_not_of("0123456789abcdefABCDEF", 2);
       if (FirstNonDigit == StringRef::npos)
         FirstNonDigit = Expr.size();
@@ -535,14 +535,14 @@ private:
   // remaining to be parsed.
   std::pair<EvalResult, StringRef> evalParensExpr(StringRef Expr,
                                                   ParseContext PCtx) const {
-    assert(Expr.startswith("(") && "Not a parenthesized expression");
+    assert(Expr.starts_with("(") && "Not a parenthesized expression");
     EvalResult SubExprResult;
     StringRef RemainingExpr;
     std::tie(SubExprResult, RemainingExpr) =
         evalComplexExpr(evalSimpleExpr(Expr.substr(1).ltrim(), PCtx), PCtx);
     if (SubExprResult.hasError())
       return std::make_pair(SubExprResult, "");
-    if (!RemainingExpr.startswith(")"))
+    if (!RemainingExpr.starts_with(")"))
       return std::make_pair(
           unexpectedToken(RemainingExpr, Expr, "expected ')'"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -554,11 +554,11 @@ private:
   // Return a pair containing the result, plus the expression remaining to be
   // parsed.
   std::pair<EvalResult, StringRef> evalLoadExpr(StringRef Expr) const {
-    assert(Expr.startswith("*") && "Not a load expression");
+    assert(Expr.starts_with("*") && "Not a load expression");
     StringRef RemainingExpr = Expr.substr(1).ltrim();
 
     // Parse read size.
-    if (!RemainingExpr.startswith("{"))
+    if (!RemainingExpr.starts_with("{"))
       return std::make_pair(EvalResult("Expected '{' following '*'."), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
     EvalResult ReadSizeExpr;
@@ -568,7 +568,7 @@ private:
     uint64_t ReadSize = ReadSizeExpr.getValue();
     if (ReadSize < 1 || ReadSize > 8)
       return std::make_pair(EvalResult("Invalid size for dereference."), "");
-    if (!RemainingExpr.startswith("}"))
+    if (!RemainingExpr.starts_with("}"))
       return std::make_pair(EvalResult("Missing '}' for dereference."), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
 
@@ -625,7 +625,7 @@ private:
       return std::make_pair(SubExprResult, RemainingExpr);
 
     // Evaluate bit-slice if present.
-    if (RemainingExpr.startswith("["))
+    if (RemainingExpr.starts_with("["))
       std::tie(SubExprResult, RemainingExpr) =
           evalSliceExpr(std::make_pair(SubExprResult, RemainingExpr));
 
@@ -645,7 +645,7 @@ private:
     StringRef RemainingExpr;
     std::tie(SubExprResult, RemainingExpr) = Ctx;
 
-    assert(RemainingExpr.startswith("[") && "Not a slice expr.");
+    assert(RemainingExpr.starts_with("[") && "Not a slice expr.");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
 
     EvalResult HighBitExpr;
@@ -654,7 +654,7 @@ private:
     if (HighBitExpr.hasError())
       return std::make_pair(HighBitExpr, RemainingExpr);
 
-    if (!RemainingExpr.startswith(":"))
+    if (!RemainingExpr.starts_with(":"))
       return std::make_pair(
           unexpectedToken(RemainingExpr, RemainingExpr, "expected ':'"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -665,7 +665,7 @@ private:
     if (LowBitExpr.hasError())
       return std::make_pair(LowBitExpr, RemainingExpr);
 
-    if (!RemainingExpr.startswith("]"))
+    if (!RemainingExpr.starts_with("]"))
       return std::make_pair(
           unexpectedToken(RemainingExpr, RemainingExpr, "expected ']'"), "");
     RemainingExpr = RemainingExpr.substr(1).ltrim();
@@ -846,7 +846,7 @@ bool RuntimeDyldCheckerImpl::checkAllRulesInBuffer(StringRef RulePrefix,
       ++LineEnd;
 
     StringRef Line(LineStart, LineEnd - LineStart);
-    if (Line.startswith(RulePrefix))
+    if (Line.starts_with(RulePrefix))
       CheckExpr += Line.substr(RulePrefix.size()).str();
 
     // If there's a check expr string...
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFAArch64.h b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFAArch64.h
index a1151b81d141..66c9753a72fd 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFAArch64.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFAArch64.h
@@ -174,7 +174,7 @@ public:
     unsigned TargetSectionID = -1;
     uint64_t TargetOffset = -1;
 
-    if (TargetName.startswith(getImportSymbolPrefix())) {
+    if (TargetName.starts_with(getImportSymbolPrefix())) {
       TargetSectionID = SectionID;
       TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName);
       TargetName = StringRef();
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFI386.h b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFI386.h
index 2a54728fd0bf..0d5afc289b8c 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFI386.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFI386.h
@@ -60,7 +60,7 @@ public:
 
     unsigned TargetSectionID = -1;
     uint64_t TargetOffset = -1;
-    if (TargetName.startswith(getImportSymbolPrefix())) {
+    if (TargetName.starts_with(getImportSymbolPrefix())) {
       TargetSectionID = SectionID;
       TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName, true);
       TargetName = StringRef();
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFThumb.h b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFThumb.h
index a3e66c6bc0ec..c079d8896c1d 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFThumb.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFThumb.h
@@ -129,7 +129,7 @@ public:
     unsigned TargetSectionID = -1;
     uint64_t TargetOffset = -1;
 
-    if (TargetName.startswith(getImportSymbolPrefix())) {
+    if (TargetName.starts_with(getImportSymbolPrefix())) {
       TargetSectionID = SectionID;
       TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName, true);
       TargetName = StringRef();
diff --git a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h
index 43ce64af8685..984a8d765c84 100644
--- a/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h
+++ b/llvm/lib/ExecutionEngine/RuntimeDyld/Targets/RuntimeDyldCOFFX86_64.h
@@ -226,7 +226,7 @@ public:
     unsigned TargetSectionID = 0;
     uint64_t TargetOffset = 0;
 
-    if (TargetName.startswith(getImportSymbolPrefix())) {
+    if (TargetName.starts_with(getImportSymbolPrefix())) {
       assert(IsExtern && "DLLImport not marked extern?");
       TargetSectionID = SectionID;
       TargetOffset = getDLLImportOffset(SectionID, Stubs, TargetName);