[JITLink][COFF] Initial COFF support.

[sunho]

Summary

Adds initial COFF support in JITLink. This is able to run a hello world c program in x86 windows successfully.

Implemented

• COFF object loader
• Static local symbols
• Absolute symbols
• External symbols
• Weak external symbols
• Common symbols
• COFF jitlink-check support
• All COMDAT selection type execpt largest
• Implicit symobl size calculation
• Rel32 relocation with PLT stub.
• IMAGE_REL_AMD64_ADDR32NB relocation

[sunho]

Add tests and rel32 relocation.

[sunho]

Finish up object file detection. Add more test cases.

[sunho]

Refactor symobol handling, calculate implicit size, support jitlink-check.

[sunho]

Support weak external symbols.

[housel]

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

136

Maybe this should be an error return rather than an assert

414

contains a selection type... are handled

[sunho]

Address comments and fix builds.

[lhames]

Really great work -- a fully separated COFFLinkGraphBuilder and x86-64 backend, test infrastructure hooked up and tests already written!

This is a big step forward for ORC Windows support.

Comments below.

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

98–100

No braces needed here.

124

MemProt Prot; will default-initialize -- no need to be explicit here.

146

No need for the brace initializers -- ArrayRef<T> will default initialize.

185

Is SectionName only used for debug logging? If so, could this be refactored into a separate function (e.g. as below)? That way it will naturally compile out when we build with NDEBUG.

std::string getSectionName(COFFSectionIndex SectionIndex, const object::coff_section *Sec) {
StringRef SectionName;
    if (SectionIndex == COFF::IMAGE_SYM_UNDEFINED) {
      if (Sym->getValue())
        return "(common)";
      else
        return "(external)";
    } else if (SectionIndex == COFF::IMAGE_SYM_ABSOLUTE)
      return "(absolute)";
    else if (SectionIndex == COFF::IMAGE_SYM_DEBUG)
      return "(debug)"; // Used with .file symbol
    else {
      // Non reserved regular section number
      if (Sec) {
        if (Expected<StringRef> SecNameOrErr = Obj.getSectionName(*SecOrErr))
          return *SecNameOrErr;
        else
          return "(section name unavailable due to error: " + toString(SecNameOrErr.takeError()) + ")";
      }
      return "(section unspecified)"
    }
}

...
    COFFSectionIndex SectionIndex = Sym->getSectionNumber();
    const object::coff_section *Sec = nullptr;

    switch (SectionIndex) {
      case COFF::IMAGE_SYM_UNDEFINED:
      case COFF::IMAGE_SYM_ABSOLUTE:
      case COFF::IMAGE_SYM_DEBUG:
        break;
      default: {
        Expected<const object::coff_section *> SecOrErr =
          Obj.getSection(SectionIndex);
        if (auto SecOrErr = Obj.getSection(SectionIndex)))
          Sec = *SecOrErr;
        else
          return make_error<JITLinkError>("Invalid COFF section number:" +
                                        formatv("{0:d}: ", SectionIndex) +
                                        " (" + toString(SecOrErr.takeError()) + ")");
    }
...
      dbgs() << "    " << SymIndex << ": Skipping FileRecord symbol \""
             << SymbolName << "\" in " << getSectionName(SectionIndex, Sec)
             << " (index: " << SectionIndex << ") \n";
      });
...

200–202

if (SecOrErr.takeError())
  return make_error<JITLinkError>("Invalid COFF section number:" +
                                  formatv("{0:d}: ", SectionIndex));

This idiom is unsafe: The .takeError() method will return an llvm::Error, and in the success case the fact that you're implicitly converting to bool will count as checking the error, but in the failure case you're not returning it, but instead creating a new Error.

Whenever you check an error you want it to be a named value, because you'll need to do something with that named value in the failure case.

Two alternative approaches are:

(1) Return the error directly (easy, maintains error type, but doesn't give context to the error):

if (auto Err = SecOrErr.takeError())
  return std::move(Err);

(2) Build a new error (loses original type, but provides more context for error messages)

if (auto Err = SecOrErr.takeError())
  return make_error<JITLinkError>("Invalid COFF section number:" +
                                  formatv("{0:d}: ", SectionIndex) +
                                  " (" + toString(std::move(Err)) + ")");

231

I'm not very familiar with COFF, but just took a look at https://docs.microsoft.com/en-us/windows/win32/debug/pe-format#auxiliary-format-3-weak-externals.

It sounds like IMAGE_SYM_CLASS_WEAK_EXTERNAL behaves differently depending on the value of the Characteristics field:

• "IMAGE_WEAK_EXTERN_SEARCH_NOLIBRARY indicates that no library search for sym1 should be performed". That sounds a bit vague, but additional conversation (e.g. here) helps to clarify:

The SVR4 ABI uses (and bfd currently supports)
the equivalent of IMAGE_WEAK_EXTERN_SEARCH_NOLIBRARY semantics (a
library member does not resolve a weak symbol unless a strong symbol
cause the member to be linked in)

Some thoughts off the top of my head:

ORC can't currently support this. ORC lookups have the related concept of a LookupKind (static linking context, or a dynamic lookup context) which we use to decide whether to pull in definitions from static archives: -- static links pull in archive defs, dynamic lookups don't.

This would be something new: "don't pull this symbol in at all, but bind it if it's already present", and it's a per-symbol behavior, rather than per-lookup.

We could support this by adding a new "ReallyWeakLinkage" type to the LinkGraph, and SymbolLookupFlags::ReallyWeaklyReferencedSymbol value.

It's worth filing a GitHub issue for this, but for now I think this patch is right to treat it as unsupported and return an error.

• "IMAGE_WEAK_EXTERN_SEARCH_LIBRARY indicates that a library search for sym1 should be performed". We can probably implement this as a plain weak external symbol in the LinkGraph. This should be added to COFFLinkGraphBuilder in this patch or a follow-up.

• "IMAGE_WEAK_EXTERN_SEARCH_ALIAS indicates that sym1 is an alias for sym2". We should add an explicit symbol alias representation to the LinkGraph -- MachO and ELF both need it too (though actual use is rare). For now the approach used in this patch is good.

352–358

If NDEBUG is set this condition will apply to Symbol->setSize(CandSize) below -- is that intended?

If the if (!CandSize) check is for debugging purposes only it can be moved inside the LLVM_DEBUG macro.

407

I guess we should be able to implement these semantics in the future with a new LinkGraph Section flags and a custom dead-stripping pass?

429–431

Does this mean that the second symbol in the sequence will always follow immediately after the first?
Do we need an array for ComdatLeaders, or just the most recent COMDAT leader symbol?

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.h

68

Can we assert !COFF::isReservedSectionNumber(SecIndex) here? Or is that already checked elsewhere?

llvm/lib/ExecutionEngine/JITLink/COFF_x86_64.cpp

48–50

This shouldn't extend Edge::Kind -- they're both enums, but there's a translation step to get from COFFX86RelocationKind to a valid Edge::Kind. I'd leave this as a plain enum with no explicit type specified.

154

This should take a COFFX86RelocationKind, rather than an Edge::Kind.

[sunho]

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

124

Looks like it doesn't default initialize, but I made it more explicit by using MemProt::None.

231

Let me do it in a follow up patch -- it will require an additional test case. Only IMAGE_WEAK_EXTERN_SEARCH_ALIAS is used in all the testcases added in this patch. Supporting alias natively in LinkGraph level is indeed interesting to look at.

407

Yes. We can dead strip these sections when parent section was dead stripped. So, we might add "parent" relationship between sections too.

429–431

In the spec, it says "The first symbol having the section value of the COMDAT section." So technically, the second symbol might be separted in the global symbol list. Practically, it should be fine to store the only most recent one though. I went with array way ultimately to potentially deal with largest symbol later. lld does some interesting "combines" of multiple COMDAT symbols to a single leader symbol when it deals with largest selection type.

[lhames]

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

124

Quite right -- my mistake!

231

Sounds good to me.

407

COFF sections are single-block, right? If so, in the short term we should use KeepAlive edges for this.

Longer term we can think about if/how to introduce COMDAT concepts into LinkGraph itself.

429–431

Do we need to worry about combines? I've been assuming that COMDAT sections are unique within an individual .o.

[sunho]

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

429–431

I looked into this again and you're right -- it should be across object files. I've updated the code to only look at most recent one and made naming more clear. To detect failrue (e.g. MC somehow sneak in comdat symbol of another section), I've added a bunch of error checkings.

[lhames]

LGTM. Thanks @sunho!

[chapuni]

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

340

LastDifferentOffset is not used with -Asserts.

[sunho]

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

340

@chapuni Hi, I'll fix this shortly. Thanks for letting me know.

[sunho]

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

340

Fixed in https://github.com/llvm/llvm-project/commit/18a6ab5b8d1f1bd44fdd8f61785922edbeb35357.

llvm/include/llvm/ExecutionEngine/JITLink/COFF.h

+//===------- COFF.h - Generic JIT link function for COFF ------*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Generic jit-link functions for COFF.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_JITLINK_COFF_H
+#define LLVM_EXECUTIONENGINE_JITLINK_COFF_H
+
+#include "llvm/ExecutionEngine/JITLink/JITLink.h"
+
+namespace llvm {
+namespace jitlink {
+
+/// Create a LinkGraph from an COFF relocatable object.
+///
+/// Note: The graph does not take ownership of the underlying buffer, nor copy
+/// its contents. The caller is responsible for ensuring that the object buffer
+/// outlives the graph.
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromCOFFObject(MemoryBufferRef ObjectBuffer);
+
+/// Link the given graph.
+///
+/// Uses conservative defaults for GOT and stub handling based on the target
+/// platform.
+void link_COFF(std::unique_ptr<LinkGraph> G,
+               std::unique_ptr<JITLinkContext> Ctx);
+
+} // end namespace jitlink
+} // end namespace llvm
+
+#endif // LLVM_EXECUTIONENGINE_JITLINK_COFF_H

llvm/include/llvm/ExecutionEngine/JITLink/COFF_x86_64.h

+//===--- COFF_x86_64.h - JIT link functions for COFF/x86-64 ---*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// jit-link functions for COFF/x86-64.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_EXECUTIONENGINE_JITLINK_COFF_X86_64_H
+#define LLVM_EXECUTIONENGINE_JITLINK_COFF_X86_64_H
+
+#include "llvm/ExecutionEngine/JITLink/JITLink.h"
+
+namespace llvm {
+namespace jitlink {
+
+/// Create a LinkGraph from an COFF/x86-64 relocatable object.
+///
+/// Note: The graph does not take ownership of the underlying buffer, nor copy
+/// its contents. The caller is responsible for ensuring that the object buffer
+/// outlives the graph.
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromCOFFObject_x86_64(MemoryBufferRef ObjectBuffer);
+
+/// jit-link the given object buffer, which must be a COFF x86-64 object file.
+void link_COFF_x86_64(std::unique_ptr<LinkGraph> G,
+                      std::unique_ptr<JITLinkContext> Ctx);
+
+/// Return the string name of the given COFF x86-64 edge kind.
+const char *getCOFFX86RelocationKindName(Edge::Kind R);
+} // end namespace jitlink
+} // end namespace llvm
+
+#endif // LLVM_EXECUTIONENGINE_JITLINK_COFF_X86_64_H

llvm/lib/ExecutionEngine/JITLink/CMakeLists.txt

add_llvm_component_library(LLVMJITLink
 
   # ELF
   ELF.cpp
   ELFLinkGraphBuilder.cpp
   ELF_aarch64.cpp
   ELF_riscv.cpp
   ELF_x86_64.cpp
 
+  # COFF
+  COFF.cpp
+  COFFLinkGraphBuilder.cpp
+  COFF_x86_64.cpp
+
   # Architectures:
   aarch64.cpp
   riscv.cpp
   x86_64.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/ExecutionEngine/JITLink
 

llvm/lib/ExecutionEngine/JITLink/COFF.cpp

+//===-------------- COFF.cpp - JIT linker function for COFF -------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// COFF jit-link function.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/JITLink/COFF.h"
+
+#include "llvm/BinaryFormat/COFF.h"
+#include "llvm/ExecutionEngine/JITLink/COFF_x86_64.h"
+#include "llvm/Object/COFF.h"
+#include "llvm/Support/Endian.h"
+#include "llvm/Support/Format.h"
+#include "llvm/Support/MemoryBuffer.h"
+#include <cstring>
+
+using namespace llvm;
+
+#define DEBUG_TYPE "jitlink"
+
+namespace llvm {
+namespace jitlink {
+
+static StringRef getMachineName(uint16_t Machine) {
+  switch (Machine) {
+  case COFF::IMAGE_FILE_MACHINE_I386:
+    return "i386";
+  case COFF::IMAGE_FILE_MACHINE_AMD64:
+    return "x86_64";
+  case COFF::IMAGE_FILE_MACHINE_ARMNT:
+    return "ARM";
+  case COFF::IMAGE_FILE_MACHINE_ARM64:
+    return "ARM64";
+  default:
+    return "unknown";
+  }
+}
+
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromCOFFObject(MemoryBufferRef ObjectBuffer) {
+  StringRef Data = ObjectBuffer.getBuffer();
+
+  // Check magic
+  auto Magic = identify_magic(ObjectBuffer.getBuffer());
+  if (Magic != file_magic::coff_object)
+    return make_error<JITLinkError>("Invalid COFF buffer");
+
+  if (Data.size() < sizeof(object::coff_file_header))
+    return make_error<JITLinkError>("Truncated COFF buffer");
+
+  uint64_t CurPtr = 0;
+  bool IsPE = false;
+
+  // Check if this is a PE/COFF file.
+  if (Data.size() >= sizeof(object::dos_header) + sizeof(COFF::PEMagic)) {
+    const auto *DH =
+        reinterpret_cast<const object::dos_header *>(Data.data() + CurPtr);
+    if (DH->Magic[0] == 'M' && DH->Magic[1] == 'Z') {
+      // Check the PE magic bytes. ("PE\0\0")
+      CurPtr = DH->AddressOfNewExeHeader;
+      if (memcmp(Data.data() + CurPtr, COFF::PEMagic, sizeof(COFF::PEMagic)) !=
+          0) {
+        return make_error<JITLinkError>("Incorrect PE magic");
+      }
+      CurPtr += sizeof(COFF::PEMagic);
+      IsPE = true;
+    }
+  }
+  if (Data.size() < CurPtr + sizeof(object::coff_file_header))
+    return make_error<JITLinkError>("Truncated COFF buffer");
+
+  const object::coff_file_header *COFFHeader =
+      reinterpret_cast<const object::coff_file_header *>(Data.data() + CurPtr);
+  const object::coff_bigobj_file_header *COFFBigObjHeader = nullptr;
+
+  // Deal with bigobj file
+  if (!IsPE && COFFHeader->Machine == COFF::IMAGE_FILE_MACHINE_UNKNOWN &&
+      COFFHeader->NumberOfSections == uint16_t(0xffff) &&
+      Data.size() >= sizeof(object::coff_bigobj_file_header)) {
+    if (Data.size() < sizeof(object::coff_file_header)) {
+      return make_error<JITLinkError>("Truncated COFF buffer");
+    }
+    COFFBigObjHeader =
+        reinterpret_cast<const object::coff_bigobj_file_header *>(Data.data() +
+                                                                  CurPtr);
+
+    // Verify that we are dealing with bigobj.
+    if (COFFBigObjHeader->Version >= COFF::BigObjHeader::MinBigObjectVersion &&
+        std::memcmp(COFFBigObjHeader->UUID, COFF::BigObjMagic,
+                    sizeof(COFF::BigObjMagic)) == 0) {
+      COFFHeader = nullptr;
+      CurPtr += sizeof(object::coff_bigobj_file_header);
+    } else
+      COFFBigObjHeader = nullptr;
+  }
+
+  uint16_t Machine =
+      COFFHeader ? COFFHeader->Machine : COFFBigObjHeader->Machine;
+  LLVM_DEBUG({
+    dbgs() << "jitLink_COFF: PE = " << (IsPE ? "yes" : "no")
+           << ", bigobj = " << (COFFBigObjHeader ? "yes" : "no")
+           << ", identifier = \"" << ObjectBuffer.getBufferIdentifier() << "\" "
+           << "machine = " << getMachineName(Machine) << "\n";
+  });
+
+  switch (Machine) {
+  case COFF::IMAGE_FILE_MACHINE_AMD64:
+    return createLinkGraphFromCOFFObject_x86_64(ObjectBuffer);
+  default:
+    return make_error<JITLinkError>(
+        "Unsupported target machine architecture in COFF object " +
+        ObjectBuffer.getBufferIdentifier() + ": " + getMachineName(Machine));
+  }
+}
+
+void link_COFF(std::unique_ptr<LinkGraph> G,
+               std::unique_ptr<JITLinkContext> Ctx) {
+  switch (G->getTargetTriple().getArch()) {
+  case Triple::x86_64:
+    link_COFF_x86_64(std::move(G), std::move(Ctx));
+    return;
+  default:
+    Ctx->notifyFailed(make_error<JITLinkError>(
+        "Unsupported target machine architecture in COFF link graph " +
+        G->getName()));
+    return;
+  }
+}
+
+} // end namespace jitlink
+} // end namespace llvm

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.h

+//===----- COFFLinkGraphBuilder.h - COFF LinkGraph builder ----*- 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Generic COFF LinkGraph building code.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LIB_EXECUTIONENGINE_JITLINK_COFFLINKGRAPHBUILDER_H
+#define LIB_EXECUTIONENGINE_JITLINK_COFFLINKGRAPHBUILDER_H
+
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/StringMap.h"
+#include "llvm/ExecutionEngine/JITLink/JITLink.h"
+#include "llvm/Object/COFF.h"
+
+#include "EHFrameSupportImpl.h"
+#include "JITLinkGeneric.h"
+
+#define DEBUG_TYPE "jitlink"
+
+#include <list>
+
+namespace llvm {
+namespace jitlink {
+
+class COFFLinkGraphBuilder {
+public:
+  virtual ~COFFLinkGraphBuilder();
+  Expected<std::unique_ptr<LinkGraph>> buildGraph();
+
+protected:
+  using COFFSectionIndex = int32_t;
+  using COFFSymbolIndex = int32_t;
+
+  COFFLinkGraphBuilder(const object::COFFObjectFile &Obj, Triple TT,
+                       LinkGraph::GetEdgeKindNameFunction GetEdgeKindName);
+
+  LinkGraph &getGraph() const { return *G; }
+
+  const object::COFFObjectFile &getObject() const { return Obj; }
+
+  virtual Error addRelocations() = 0;
+
+  Error graphifySections();
+  Error graphifySymbols();
+
+  void setGraphSymbol(COFFSectionIndex SecIndex, COFFSymbolIndex SymIndex,
+                      Symbol &Sym) {
+    assert(!GraphSymbols[SymIndex] && "Duplicate symbol at index");
+    GraphSymbols[SymIndex] = &Sym;
+    if (!COFF::isReservedSectionNumber(SecIndex))
+      SymbolSets[SecIndex].insert({Sym.getOffset(), &Sym});
+  }
+
+  Symbol *getGraphSymbol(COFFSymbolIndex SymIndex) const {
+    if (SymIndex < 0 || SymIndex >= GraphSymbols.size())
+      return nullptr;
+    return GraphSymbols[SymIndex];
+  }
+
+  void setGraphBlock(COFFSectionIndex SecIndex, Block *B) {
+    assert(!GraphBlocks[SecIndex] && "Duplicate section at index");
+    GraphBlocks[SecIndex] = B;
+  }
+
+  Block *getGraphBlock(COFFSectionIndex SecIndex) const {
+    if (SecIndex <= 0 || SecIndex >= GraphSymbols.size())
+      return nullptr;
+    return GraphBlocks[SecIndex];
+  }
+
+  object::COFFObjectFile::section_iterator_range sections() const {
+    return Obj.sections();
+  }
+
+  /// Traverse all matching relocation records in the given section. The handler
+  /// function Func should be callable with this signature:
+  ///   Error(const object::RelocationRef&,
+  ///         const object::SectionRef&, Section &)
+  ///
+  template <typename RelocHandlerFunction>
+  Error forEachRelocation(const object::SectionRef &RelSec,
+                          RelocHandlerFunction &&Func,
+                          bool ProcessDebugSections = false);
+
+  /// Traverse all matching relocation records in the given section. Convenience
+  /// wrapper to allow passing a member function for the handler.
+  ///
+  template <typename ClassT, typename RelocHandlerMethod>
+  Error forEachRelocation(const object::SectionRef &RelSec, ClassT *Instance,
+                          RelocHandlerMethod &&Method,
+                          bool ProcessDebugSections = false) {
+    return forEachRelocation(
+        RelSec,
+        [Instance, Method](const auto &Rel, const auto &Target, auto &GS) {
+          return (Instance->*Method)(Rel, Target, GS);
+        },
+        ProcessDebugSections);
+  }
+
+private:
+  // The first symbol of COMDAT sequence.
+  // This symbol contains the actual definition of the symbol and proper linkage
+  // mode specified by the selection type. This symbol will be exported when
+  // second symbol of COMDAT sequence is processed which contains the external
+  // name of the symbol.
+  struct ComdatLeader {
+    COFFSymbolIndex Index;
+    Linkage Linkage;
+  };
+  std::vector<Optional<ComdatLeader>> ComdatLeaders;
+
+  // This represents a pending request to create a weak external symbol with a
+  // name.
+  struct WeakAliasRequest {
+    COFFSymbolIndex Alias;
+    COFFSymbolIndex Target;
+    StringRef SymbolName;
+  };
+  std::vector<WeakAliasRequest> WeakAliasRequests;
+
+  // Per COFF section jitlink symbol set sorted by offset.
+  // Used for calculating implicit size of defined symbols.
+  // vector of set is used to have O(log n) time complexity for
+  // sorted symbol insertion.
+  using SymbolSet = std::set<std::pair<orc::ExecutorAddrDiff, Symbol *>>;
+  std::vector<SymbolSet> SymbolSets;
+
+  Section &getCommonSection();
+
+  Expected<Symbol *> createDefinedSymbol(COFFSymbolIndex SymIndex,
+                                         StringRef SymbolName,
+                                         object::COFFSymbolRef Symbol,
+                                         const object::coff_section *Section);
+  Expected<Symbol *> createCOMDATLeaderSymbol(
+      COFFSymbolIndex SymIndex, object::COFFSymbolRef Symbol,
+      const object::coff_aux_section_definition *Definition);
+  Expected<Symbol *> exportCOMDATSymbol(COFFSymbolIndex SymIndex,
+                                        StringRef SymbolName,
+                                        object::COFFSymbolRef Symbol);
+  Error flushWeakAliasRequests();
+  Error calculateImplicitSizeOfSymbols();
+
+  static uint64_t getSectionAddress(const object::COFFObjectFile &Obj,
+                                    const object::coff_section *Section);
+  static uint64_t getSectionSize(const object::COFFObjectFile &Obj,
+                                 const object::coff_section *Section);
+  static bool isComdatSection(const object::coff_section *Section);
+  static unsigned getPointerSize(const object::COFFObjectFile &Obj);
+  static support::endianness getEndianness(const object::COFFObjectFile &Obj);
+
+  const object::COFFObjectFile &Obj;
+  std::unique_ptr<LinkGraph> G;
+
+  Section *CommonSection = nullptr;
+  std::vector<Block *> GraphBlocks;
+  std::vector<Symbol *> GraphSymbols;
+};
+
+template <typename RelocHandlerFunction>
+Error COFFLinkGraphBuilder::forEachRelocation(const object::SectionRef &RelSec,
+                                              RelocHandlerFunction &&Func,
+                                              bool ProcessDebugSections) {
+
+  auto COFFRelSect = Obj.getCOFFSection(RelSec);
+
+  // Target sections have names in valid ELF object files.
+  Expected<StringRef> Name = Obj.getSectionName(COFFRelSect);
+  if (!Name)
+    return Name.takeError();
+  LLVM_DEBUG(dbgs() << "  " << *Name << ":\n");
+
+  // Lookup the link-graph node corresponding to the target section name.
+  auto *BlockToFix = getGraphBlock(RelSec.getIndex() + 1);
+  if (!BlockToFix)
+    return make_error<StringError>(
+        "Referencing a section that wasn't added to the graph: " + *Name,
+        inconvertibleErrorCode());
+
+  // Let the callee process relocation entries one by one.
+  for (const auto &R : RelSec.relocations())
+    if (Error Err = Func(R, RelSec, *BlockToFix))
+      return Err;
+
+  LLVM_DEBUG(dbgs() << "\n");
+  return Error::success();
+}
+
+} // end namespace jitlink
+} // end namespace llvm
+
+#endif // LIB_EXECUTIONENGINE_JITLINK_COFFLINKGRAPHBUILDER_H

llvm/lib/ExecutionEngine/JITLink/COFFLinkGraphBuilder.cpp

+//=--------- COFFLinkGraphBuilder.cpp - COFF LinkGraph builder ----------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// Generic COFF LinkGraph buliding code.
+//
+//===----------------------------------------------------------------------===//
+#include "COFFLinkGraphBuilder.h"
+
+#define DEBUG_TYPE "jitlink"
+
+static const char *CommonSectionName = "__common";
+
+namespace llvm {
+namespace jitlink {
+
+COFFLinkGraphBuilder::COFFLinkGraphBuilder(
+    const object::COFFObjectFile &Obj, Triple TT,
+    LinkGraph::GetEdgeKindNameFunction GetEdgeKindName)
+    : G(std::make_unique<LinkGraph>(
+          Obj.getFileName().str(), Triple(std::move(TT)), getPointerSize(Obj),
+          getEndianness(Obj), std::move(GetEdgeKindName))),
+      Obj(Obj) {
+  LLVM_DEBUG({
+    dbgs() << "Created COFFLinkGraphBuilder for \"" << Obj.getFileName()
+           << "\"\n";
+  });
+}
+
+COFFLinkGraphBuilder::~COFFLinkGraphBuilder() = default;
+
+unsigned
+COFFLinkGraphBuilder::getPointerSize(const object::COFFObjectFile &Obj) {
+  return Obj.getBytesInAddress();
+}
+
+support::endianness
+COFFLinkGraphBuilder::getEndianness(const object::COFFObjectFile &Obj) {
+  return Obj.isLittleEndian() ? support::little : support::big;
+}
+
+uint64_t COFFLinkGraphBuilder::getSectionSize(const object::COFFObjectFile &Obj,
+                                              const object::coff_section *Sec) {
+  // Consider the difference between executable form and object form.
+  // More information is inside COFFObjectFile::getSectionSize
+  if (Obj.getDOSHeader())
+    return std::min(Sec->VirtualSize, Sec->SizeOfRawData);
+  return Sec->SizeOfRawData;
+}
+
+uint64_t
+COFFLinkGraphBuilder::getSectionAddress(const object::COFFObjectFile &Obj,
+                                        const object::coff_section *Section) {
+  return Section->VirtualAddress + Obj.getImageBase();
+}
+
+bool COFFLinkGraphBuilder::isComdatSection(
+    const object::coff_section *Section) {
+  return Section->Characteristics & COFF::IMAGE_SCN_LNK_COMDAT;
+}
+
+Section &COFFLinkGraphBuilder::getCommonSection() {
+  if (!CommonSection)
+    CommonSection =
+        &G->createSection(CommonSectionName, MemProt::Read | MemProt::Write);
+  return *CommonSection;
+}
+
+Expected<std::unique_ptr<LinkGraph>> COFFLinkGraphBuilder::buildGraph() {
+  if (!Obj.isRelocatableObject())
+    return make_error<JITLinkError>("Object is not a relocatable COFF file");
+
+  if (auto Err = graphifySections())
+    return std::move(Err);
+
+  if (auto Err = graphifySymbols())
+    return std::move(Err);
+
+  if (auto Err = addRelocations())
+    return std::move(Err);
+
+  return std::move(G);
+}
+
+Error COFFLinkGraphBuilder::graphifySections() {
+  LLVM_DEBUG(dbgs() << "  Creating graph sections...\n");
+
+  GraphBlocks.resize(Obj.getNumberOfSections() + 1);
+  // For each section...
+  for (COFFSectionIndex SecIndex = 1; SecIndex <= Obj.getNumberOfSections();
+       SecIndex++) {
+    Expected<const object::coff_section *> Sec = Obj.getSection(SecIndex);
+    if (!Sec) {
+      return Sec.takeError();
+    }
+
+    StringRef SectionName;
+    if (Expected<StringRef> SecNameOrErr = Obj.getSectionName(*Sec))
+      SectionName = *SecNameOrErr;
+
+    bool IsDiscardable =
+        (*Sec)->Characteristics &
+        (COFF::IMAGE_SCN_MEM_DISCARDABLE | COFF::IMAGE_SCN_LNK_INFO);
+    dbgs() << getSectionSize(Obj, *Sec) << "\n";
+    if (IsDiscardable) {
+      LLVM_DEBUG(dbgs() << "    " << SecIndex << ": \"" << SectionName
+                        << "\" is discardable: "
+                           "No graph section will be created.\n");
+      continue;
+    }
+
+    // FIXME: Skip debug info sections
+
+    LLVM_DEBUG({
+      dbgs() << "    "
+             << "Creating section for \"" << SectionName << "\"\n";
+    });
+
+    // Get the section's memory protection flags.
+    MemProt Prot = {};
+    if ((*Sec)->Characteristics & COFF::IMAGE_SCN_MEM_EXECUTE)
+      Prot |= MemProt::Exec;
+    if ((*Sec)->Characteristics & COFF::IMAGE_SCN_MEM_READ)
+      Prot |= MemProt::Read;
+    if ((*Sec)->Characteristics & COFF::IMAGE_SCN_MEM_WRITE)
+      Prot |= MemProt::Write;
+
+    // Look for existing sections first.
+    auto *GraphSec = G->findSectionByName(SectionName);
+    if (!GraphSec)
+      GraphSec = &G->createSection(SectionName, Prot);
+    assert(GraphSec->getMemProt() == Prot && "MemProt should match");
+
+    Block *B = nullptr;
+    if ((*Sec)->Characteristics & COFF::IMAGE_SCN_CNT_UNINITIALIZED_DATA)
+      B = &G->createZeroFillBlock(
+          *GraphSec, getSectionSize(Obj, *Sec),
+          orc::ExecutorAddr(getSectionAddress(Obj, *Sec)),
+          (*Sec)->getAlignment(), 0);
+    else {
+      ArrayRef<uint8_t> Data{};
+      if (auto Err = Obj.getSectionContents(*Sec, Data))
+        return Err;
+
+      B = &G->createContentBlock(
+          *GraphSec,
+          ArrayRef<char>(reinterpret_cast<const char *>(Data.data()),
+                         Data.size()),
+          orc::ExecutorAddr(getSectionAddress(Obj, *Sec)),
+          (*Sec)->getAlignment(), 0);
+    }
+
+    setGraphBlock(SecIndex, B);
+  }
+
+  return Error::success();
+}
+
+Error COFFLinkGraphBuilder::graphifySymbols() {
+  LLVM_DEBUG(dbgs() << "  Creating graph symbols...\n");
+
+  ComdatLeaders.resize(Obj.getNumberOfSections() + 1);
+  SymbolSets.resize(Obj.getNumberOfSections() + 1);
+  GraphSymbols.resize(Obj.getNumberOfSymbols());
+
+  for (COFFSymbolIndex SymIndex = 0; SymIndex < Obj.getNumberOfSymbols();
+       SymIndex++) {
+    Expected<object::COFFSymbolRef> Sym = Obj.getSymbol(SymIndex);
+    if (!Sym)
+      return Sym.takeError();
+
+    StringRef SymbolName;
+    if (Expected<StringRef> SymNameOrErr = Obj.getSymbolName(*Sym))
+      SymbolName = *SymNameOrErr;
+
+    COFFSectionIndex SectionIndex = Sym->getSectionNumber();
+    const object::coff_section *Sec = nullptr;
+
+    // Get section name
+    StringRef SectionName;
+    if (SectionIndex == COFF::IMAGE_SYM_UNDEFINED) {
+      if (Sym->getValue())
+        SectionName = "(common)";
+      else
+        SectionName = "(external)";
+    } else if (SectionIndex == COFF::IMAGE_SYM_ABSOLUTE)
+      SectionName = "(absolute)";
+    else if (SectionIndex == COFF::IMAGE_SYM_DEBUG) {
+      // Used with .file symbol
+      SectionName = "(debug)";
+    } else {
+      // Non reserved regular section number
+      Expected<const object::coff_section *> SecOrErr =
+          Obj.getSection(SectionIndex);
+      if (SecOrErr.takeError())
+        return make_error<JITLinkError>("Invalid COFF section number:" +
+                                        formatv("{0:d}: ", SectionIndex));
+      if (Expected<StringRef> SecNameOrErr = Obj.getSectionName(*SecOrErr))
+        SectionName = *SecNameOrErr;
+      Sec = *SecOrErr;
+    }
+
+    // Create jitlink symbol
+    jitlink::Symbol *GSym = nullptr;
+    if (Sym->isFileRecord())
+      LLVM_DEBUG({
+        dbgs() << "    " << SymIndex << ": Skipping FileRecord symbol \""
+               << SymbolName << "\" in " << SectionName
+               << " (index: " << SectionIndex << ") \n";
+      });
+    else if (Sym->isUndefined()) {
+      LLVM_DEBUG({
+        dbgs() << "    " << SymIndex
+               << ": Creating external graph symbol for COFF symbol \""
+               << SymbolName << "\" in " << SectionName
+               << " (index: " << SectionIndex << ") \n";
+      });
+      GSym =
+          &G->addExternalSymbol(SymbolName, Sym->getValue(), Linkage::Strong);
+    } else if (Sym->isWeakExternal()) {
+      COFFSymbolIndex TagIndex =
+          Sym->getAux<object::coff_aux_weak_external>()->TagIndex;
+      WeakAliasRequests.push_back({SymIndex, TagIndex, SymbolName});
+    } else {
+      Expected<jitlink::Symbol *> NewGSym =
+          createDefinedSymbol(SymIndex, SymbolName, *Sym, Sec);
+      if (!NewGSym) {
+        LLVM_DEBUG({
+          dbgs() << "    " << SymIndex
+                 << ": Not creating graph symbol for COFF symbol \""
+                 << SymbolName << "\" in " << SectionName
+                 << " with an error : " << NewGSym.takeError() << "\n";
+        });
+        SymIndex += Sym->getNumberOfAuxSymbols();
+        continue;
+      }
+      GSym = *NewGSym;
+      if (GSym) {
+        LLVM_DEBUG({
+          dbgs() << "    " << SymIndex
+                 << ": Creating defined graph symbol for COFF symbol \""
+                 << SymbolName << "\" in " << SectionName
+                 << " (index: " << SectionIndex << ") \n";
+          dbgs() << "      " << *GSym << "\n";
+        });
+      }
+    }
+
+    // Register the symbol
+    if (GSym)
+      setGraphSymbol(SectionIndex, SymIndex, *GSym);
+    SymIndex += Sym->getNumberOfAuxSymbols();
+  }
+
+  if (auto Err = flushWeakAliasRequests())
+    return Err;
+
+  if (auto Err = calculateImplicitSizeOfSymbols())
+    return Err;
+
+  return Error::success();
+}
+
+Error COFFLinkGraphBuilder::flushWeakAliasRequests() {
+  // Export the weak external symbols and alias it
+  for (auto &WeakAlias : WeakAliasRequests) {
+    if (auto *Target = getGraphSymbol(WeakAlias.Target)) {
+      assert((llvm::count_if(G->defined_symbols(),
+                             [&](const jitlink::Symbol *Sym) {
+                               return Sym->getName() == WeakAlias.SymbolName;
+                             }) == 0) &&
+             "Duplicate defined symbol");
+
+      Expected<object::COFFSymbolRef> AliasSymbol =
+          Obj.getSymbol(WeakAlias.Alias);
+      if (!AliasSymbol)
+        return AliasSymbol.takeError();
+
+      jitlink::Symbol *NewSymbol = &G->addDefinedSymbol(
+          Target->getBlock(), Target->getOffset(), WeakAlias.SymbolName,
+          Target->getSize(), Linkage::Weak, Scope::Default,
+          Target->isCallable(), false);
+      setGraphSymbol(AliasSymbol->getSectionNumber(), WeakAlias.Alias,
+                     *NewSymbol);
+      LLVM_DEBUG({
+        dbgs() << "    " << WeakAlias.Alias
+               << ": Creating weak external symbol for COFF symbol \""
+               << WeakAlias.SymbolName << "\" in section "
+               << AliasSymbol->getSectionNumber() << "\n";
+        dbgs() << "      " << *NewSymbol << "\n";
+      });
+    } else
+      return make_error<JITLinkError>("Weak symbol alias requested but actual "
+                                      "symbol not defined in symbol " +
+                                      WeakAlias.Alias);
+  }
+  return Error::success();
+}
+
+Error COFFLinkGraphBuilder::calculateImplicitSizeOfSymbols() {
+  for (COFFSectionIndex SecIndex = 1; SecIndex <= Obj.getNumberOfSections();
+       SecIndex++) {
+    auto &SymbolSet = SymbolSets[SecIndex];
+    jitlink::Block *B = getGraphBlock(SecIndex);
+    orc::ExecutorAddrDiff LastOffset = B->getSize();
+    orc::ExecutorAddrDiff LastDifferentOffset = B->getSize();
+    orc::ExecutorAddrDiff LastSize = 0;
+    for (auto It = SymbolSet.rbegin(); It != SymbolSet.rend(); It++) {
+      orc::ExecutorAddrDiff Offset = It->first;
+      jitlink::Symbol *Symbol = It->second;
+      orc::ExecutorAddrDiff CandSize;
+      // Last offset can be same when aliasing happened
+      if (Symbol->getOffset() == LastOffset)
+        CandSize = LastSize;
+      else
+        CandSize = LastOffset - Offset;
+
+      if (LastOffset != Offset)
+        LastDifferentOffset = Offset;
+      LastSize = CandSize;
+      LastOffset = Offset;
+      if (Symbol->getSize()) {
+        // Non empty symbol can happen by COMDAT symbol.
+        // We don't consider the possibility of overlapping symbol range that
+        // could be introduced by disparity between inferred symbol size and
+        // defined symbol size because symbol size information is currently only
+        // used by jitlink-check.
+        LLVM_DEBUG({
+          if (Offset + Symbol->getSize() > LastDifferentOffset)
+            dbgs() << "  Overlapping symbol range generated for the following "
+                      "symbol:"
+                   << "\n"
+                   << "    " << *Symbol << "\n";
+        });
+        (void)LastDifferentOffset;
+        continue;
+      }
+      if (!CandSize)
+        LLVM_DEBUG({
+          dbgs() << "  Empty implicit symbol size generated for the following "
+                    "symbol:"
+                 << "\n"
+                 << "    " << *Symbol << "\n";
+        });
+
+      Symbol->setSize(CandSize);
+    }
+  }
+  return Error::success();
+}
+
+Expected<Symbol *> COFFLinkGraphBuilder::createDefinedSymbol(
+    COFFSymbolIndex SymIndex, StringRef SymbolName,
+    object::COFFSymbolRef Symbol, const object::coff_section *Section) {
+  if (Symbol.isCommon()) {
+    // FIXME: correct alignment
+    return &G->addCommonSymbol(SymbolName, Scope::Default, getCommonSection(),
+                               orc::ExecutorAddr(), Symbol.getValue(),
+                               Symbol.getValue(), false);
+  }
+  if (Symbol.isAbsolute())
+    return &G->addAbsoluteSymbol(SymbolName,
+                                 orc::ExecutorAddr(Symbol.getValue()), 0,
+                                 Linkage::Strong, Scope::Local, false);
+
+  if (llvm::COFF::isReservedSectionNumber(Symbol.getSectionNumber()))
+    return make_error<JITLinkError>(
+        "Reserved section number used in regular symbol " +
+        formatv("{0:d}", SymIndex));
+
+  Block *B = getGraphBlock(Symbol.getSectionNumber());
+  if (Symbol.isExternal()) {
+    // This is not a comdat sequence, export the symbol as it is
+    if (!ComdatLeaders[Symbol.getSectionNumber()])
+      return &G->addDefinedSymbol(
+          *B, Symbol.getValue(), SymbolName, 0, Linkage::Strong, Scope::Default,
+          Symbol.getComplexType() == COFF::IMAGE_SYM_DTYPE_FUNCTION, false);
+    else
+      return exportCOMDATSymbol(SymIndex, SymbolName, Symbol);
+  }
+
+  if (Symbol.getStorageClass() == COFF::IMAGE_SYM_CLASS_STATIC) {
+    const object::coff_aux_section_definition *Definition =
+        Symbol.getSectionDefinition();
+    if (!Definition || !isComdatSection(Section) ||
+        ComdatLeaders[Symbol.getSectionNumber()]) {
+      // Handle typical static symbol
+      return &G->addDefinedSymbol(
+          *B, Symbol.getValue(), SymbolName, 0, Linkage::Strong, Scope::Local,
+          Symbol.getComplexType() == COFF::IMAGE_SYM_DTYPE_FUNCTION, false);
+    }
+    if (Definition->Selection == COFF::IMAGE_COMDAT_SELECT_ASSOCIATIVE) {
+      // FIXME: don't dead strip this when parent section is alive
+      return &G->addDefinedSymbol(
+          *B, Symbol.getValue(), SymbolName, 0, Linkage::Strong, Scope::Local,
+          Symbol.getComplexType() == COFF::IMAGE_SYM_DTYPE_FUNCTION, false);
+    }
+
+    return createCOMDATLeaderSymbol(SymIndex, Symbol, Definition);
+  }
+  return make_error<JITLinkError>("Unsupported storage class " +
+                                  formatv("{0:d}", Symbol.getStorageClass()) +
+                                  " in symbol " + formatv("{0:d}", SymIndex));
+}
+// COMDAT handling:
+// When IMAGE_SCN_LNK_COMDAT flag is set in the flags of a section,
+// the section is called a COMDAT section. It contains two symbols
+// in a sequence that specifes the behavior. First symbol is the section
+// symbol which contains the size and name of the section. It also contains
+// selectino type that specifies how duplicates of the symbol is handled.
+// Second symbol is COMDAT symbol which usually defines the external name and
+// data type.
+//
+// Since two symbols always come in a specific order, we store the first
+// symbol to ComdatLeaders table and emits it as a external symbol when
+// we encounter the COMDAT symbol.
+
+// Process the first symbol of COMDAT sequence.
+Expected<Symbol *> COFFLinkGraphBuilder::createCOMDATLeaderSymbol(
+    COFFSymbolIndex SymIndex, object::COFFSymbolRef Symbol,
+    const object::coff_aux_section_definition *Definition) {
+  Block *B = getGraphBlock(Symbol.getSectionNumber());
+  Linkage L = Linkage::Strong;
+  switch (Definition->Selection) {
+  case COFF::IMAGE_COMDAT_SELECT_NODUPLICATES: {
+    L = Linkage::Strong;
+    break;
+  }
+  case COFF::IMAGE_COMDAT_SELECT_ANY: {
+    L = Linkage::Weak;
+    break;
+  }
+  case COFF::IMAGE_COMDAT_SELECT_EXACT_MATCH:
+  case COFF::IMAGE_COMDAT_SELECT_SAME_SIZE: {
+    // FIXME: Implement size/content validation when LinkGraph is able to
+    // handle this.
+    L = Linkage::Weak;
+    break;
+  }
+  case COFF::IMAGE_COMDAT_SELECT_LARGEST: {
+    // FIXME: Support IMAGE_COMDAT_SELECT_LARGEST when LinkGraph is able to
+    // handle this.
+    return make_error<JITLinkError>(
+        "IMAGE_COMDAT_SELECT_LARGEST is not supported.");
+  }
+  case COFF::IMAGE_COMDAT_SELECT_NEWEST: {
+    // Even link.exe doesn't support this selection properly.
+    return make_error<JITLinkError>(
+        "IMAGE_COMDAT_SELECT_NEWEST is not supported.");
+  }
+  default: {
+    return make_error<JITLinkError>("Invalid comdat selection type: " +
+                                    formatv("{0:d}", Definition->Selection));
+  }
+  }
+  return &G->addAnonymousSymbol(*B, Symbol.getValue(), Definition->Length,
+                                false, false);
+}
+
+// Process the second symbol of COMDAT sequence.
+Expected<Symbol *>
+COFFLinkGraphBuilder::exportCOMDATSymbol(COFFSymbolIndex SymIndex,
+                                         StringRef SymbolName,
+                                         object::COFFSymbolRef Symbol) {
+  auto Leader = *ComdatLeaders[Symbol.getSectionNumber()];
+  COFFSymbolIndex TargetIndex = Leader.Index;
+  Linkage L = Leader.Linkage;
+  jitlink::Symbol *Target = getGraphSymbol(TargetIndex);
+  assert(Target && "COMDAT leaader is invalid.");
+  assert((llvm::count_if(G->defined_symbols(),
+                         [&](const jitlink::Symbol *Sym) {
+                           return Sym->getName() == SymbolName;
+                         }) == 0) &&
+         "Duplicate defined symbol");
+  Target->setName(SymbolName);
+  Target->setLinkage(L);
+  Target->setCallable(Symbol.getComplexType() ==
+                      COFF::IMAGE_SYM_DTYPE_FUNCTION);
+  Target->setScope(Scope::Default);
+  LLVM_DEBUG({
+    dbgs() << "    " << SymIndex
+           << ": Exporting COMDAT graph symbol for COFF symbol \"" << SymbolName
+           << "\" in section " << Symbol.getSectionNumber() << "\n";
+    dbgs() << "      " << *Target << "\n";
+  });
+  return Target;
+}
+
+} // namespace jitlink
+} // namespace llvm
 No newline at end of file

llvm/lib/ExecutionEngine/JITLink/COFF_x86_64.cpp

+//===----- COFF_x86_64.cpp - JIT linker implementation for ELF/aarch64 ----===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// COFF/x86_64 jit-link implementation.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/ExecutionEngine/JITLink/COFF_x86_64.h"
+#include "COFFLinkGraphBuilder.h"
+#include "EHFrameSupportImpl.h"
+#include "JITLinkGeneric.h"
+#include "llvm/BinaryFormat/COFF.h"
+#include "llvm/ExecutionEngine/JITLink/x86_64.h"
+#include "llvm/Object/COFF.h"
+#include "llvm/Support/Endian.h"
+
+#define DEBUG_TYPE "jitlink"
+
+using namespace llvm;
+using namespace llvm::jitlink;
+
+namespace {
+
+class COFFJITLinker_x86_64 : public JITLinker<COFFJITLinker_x86_64> {
+  friend class JITLinker<COFFJITLinker_x86_64>;
+
+public:
+  COFFJITLinker_x86_64(std::unique_ptr<JITLinkContext> Ctx,
+                       std::unique_ptr<LinkGraph> G,
+                       PassConfiguration PassConfig)
+      : JITLinker(std::move(Ctx), std::move(G), std::move(PassConfig)) {}
+
+private:
+  Error applyFixup(LinkGraph &G, Block &B, const Edge &E) const {
+    return x86_64::applyFixup(G, B, E, nullptr);
+  }
+};
+
+class COFFLinkGraphBuilder_x86_64 : public COFFLinkGraphBuilder {
+private:
+  enum COFFX86RelocationKind : Edge::Kind {
+    COFFAddr32NB = Edge::FirstRelocation,
+    COFFRel32,
+  };
+
+  static Expected<COFFX86RelocationKind>
+  getRelocationKind(const uint32_t Type) {
+    switch (Type) {
+    case COFF::RelocationTypeAMD64::IMAGE_REL_AMD64_ADDR32NB:
+      return COFFAddr32NB;
+    case COFF::RelocationTypeAMD64::IMAGE_REL_AMD64_REL32:
+      return COFFRel32;
+    }
+
+    return make_error<JITLinkError>("Unsupported x86_64 relocation:" +
+                                    formatv("{0:d}", Type));
+  }
+
+  Error addRelocations() override {
+
+    LLVM_DEBUG(dbgs() << "Processing relocations:\n");
+
+    for (const auto &RelSect : sections())
+      if (Error Err = COFFLinkGraphBuilder::forEachRelocation(
+              RelSect, this, &COFFLinkGraphBuilder_x86_64::addSingleRelocation))
+        return Err;
+
+    return Error::success();
+  }
+
+  Error addSingleRelocation(const object::RelocationRef &Rel,
+                            const object::SectionRef &FixupSect,
+                            Block &BlockToFix) {
+
+    const object::coff_relocation *COFFRel = getObject().getCOFFRelocation(Rel);
+    auto SymbolIt = Rel.getSymbol();
+    if (SymbolIt == getObject().symbol_end()) {
+      return make_error<StringError>(
+          formatv("Invalid symbol index in relocation entry. "
+                  "index: {0}, section: {1}",
+                  COFFRel->SymbolTableIndex, FixupSect.getIndex()),
+          inconvertibleErrorCode());
+    }
+
+    object::COFFSymbolRef COFFSymbol = getObject().getCOFFSymbol(*SymbolIt);
+    COFFSymbolIndex SymIndex = getObject().getSymbolIndex(COFFSymbol);
+
+    Symbol *GraphSymbol = getGraphSymbol(SymIndex);
+    if (!GraphSymbol)
+      return make_error<StringError>(
+          formatv("Could not find symbol at given index, did you add it to "
+                  "JITSymbolTable? index: {0}, section: {1}",
+                  SymIndex, FixupSect.getIndex()),
+          inconvertibleErrorCode());
+
+    Expected<COFFX86RelocationKind> RelocKind =
+        getRelocationKind(Rel.getType());
+    if (!RelocKind)
+      return RelocKind.takeError();
+
+    int64_t Addend = 0;
+    orc::ExecutorAddr FixupAddress =
+        orc::ExecutorAddr(FixupSect.getAddress()) + Rel.getOffset();
+    Edge::OffsetT Offset = FixupAddress - BlockToFix.getAddress();
+
+    // Get a pointer to the fixup content.
+    const void *FixupContent = BlockToFix.getContent().data() +
+                               (FixupAddress - BlockToFix.getAddress());
+
+    Edge::Kind Kind = Edge::Invalid;
+
+    switch (*RelocKind) {
+    case COFFAddr32NB: {
+      Kind = x86_64::Pointer32;
+      break;
+    }
+    case COFFRel32: {
+      Kind = x86_64::BranchPCRel32;
+      break;
+    }
+    };
+
+    Edge GE(Kind, Offset, *GraphSymbol, Addend);
+    LLVM_DEBUG({
+      dbgs() << "    ";
+      printEdge(dbgs(), BlockToFix, GE, x86_64::getEdgeKindName(Kind));
+      dbgs() << "\n";
+    });
+
+    BlockToFix.addEdge(std::move(GE));
+    return Error::success();
+  }
+
+  /// Return the string name of the given COFF x86_64 edge kind.
+  const char *getCOFFX86RelocationKindName(Edge::Kind R) {
+    switch (R) {
+    case COFFAddr32NB:
+      return "COFFAddr32NB";
+    case COFFRel32:
+      return "COFFRel32";
+    default:
+      return getGenericEdgeKindName(static_cast<Edge::Kind>(R));
+    }
+  }
+
+public:
+  COFFLinkGraphBuilder_x86_64(const object::COFFObjectFile &Obj, const Triple T)
+      : COFFLinkGraphBuilder(Obj, std::move(T), x86_64::getEdgeKindName) {}
+};
+
+Error buildTables_COFF_x86_64(LinkGraph &G) {
+  LLVM_DEBUG(dbgs() << "Visiting edges in graph:\n");
+
+  x86_64::GOTTableManager GOT;
+  x86_64::PLTTableManager PLT(GOT);
+  visitExistingEdges(G, GOT, PLT);
+  return Error::success();
+}
+} // namespace
+
+namespace llvm {
+namespace jitlink {
+
+Expected<std::unique_ptr<LinkGraph>>
+createLinkGraphFromCOFFObject_x86_64(MemoryBufferRef ObjectBuffer) {
+  LLVM_DEBUG({
+    dbgs() << "Building jitlink graph for new input "
+           << ObjectBuffer.getBufferIdentifier() << "...\n";
+  });
+
+  auto COFFObj = object::ObjectFile::createCOFFObjectFile(ObjectBuffer);
+  if (!COFFObj)
+    return COFFObj.takeError();
+
+  return COFFLinkGraphBuilder_x86_64(**COFFObj, (*COFFObj)->makeTriple())
+      .buildGraph();
+}
+
+void link_COFF_x86_64(std::unique_ptr<LinkGraph> G,
+                      std::unique_ptr<JITLinkContext> Ctx) {
+  PassConfiguration Config;
+  const Triple &TT = G->getTargetTriple();
+  if (Ctx->shouldAddDefaultTargetPasses(TT)) {
+    // Add a mark-live pass.
+    if (auto MarkLive = Ctx->getMarkLivePass(TT))
+      Config.PrePrunePasses.push_back(std::move(MarkLive));
+    else
+      Config.PrePrunePasses.push_back(markAllSymbolsLive);
+
+    // Add an in-place GOT/Stubs/TLSInfoEntry build pass.
+    Config.PostPrunePasses.push_back(buildTables_COFF_x86_64);
+
+    // Add GOT/Stubs optimizer pass.
+    Config.PreFixupPasses.push_back(x86_64::optimizeGOTAndStubAccesses);
+  }
+
+  if (auto Err = Ctx->modifyPassConfig(*G, Config))
+    return Ctx->notifyFailed(std::move(Err));
+
+  COFFJITLinker_x86_64::link(std::move(Ctx), std::move(G), std::move(Config));
+}
+
+} // namespace jitlink
+} // namespace llvm

llvm/lib/ExecutionEngine/JITLink/JITLink.cpp

 //===------------- JITLink.cpp - Core Run-time JIT linker APIs ------------===//
 //
 // 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/JITLink/JITLink.h"
 
 #include "llvm/BinaryFormat/Magic.h"
+#include "llvm/ExecutionEngine/JITLink/COFF.h"
 #include "llvm/ExecutionEngine/JITLink/ELF.h"
 #include "llvm/ExecutionEngine/JITLink/MachO.h"
 #include "llvm/Support/Format.h"
 #include "llvm/Support/ManagedStatic.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
 
 using namespace llvm;

 Expected<std::unique_ptr<LinkGraph>>
 createLinkGraphFromObject(MemoryBufferRef ObjectBuffer) {
   auto Magic = identify_magic(ObjectBuffer.getBuffer());
   switch (Magic) {
   case file_magic::macho_object:
     return createLinkGraphFromMachOObject(ObjectBuffer);
   case file_magic::elf_relocatable:
     return createLinkGraphFromELFObject(ObjectBuffer);
+  case file_magic::coff_object:
+    return createLinkGraphFromCOFFObject(ObjectBuffer);
   default:
     return make_error<JITLinkError>("Unsupported file format");
   };
 }
 
 void link(std::unique_ptr<LinkGraph> G, std::unique_ptr<JITLinkContext> Ctx) {
   switch (G->getTargetTriple().getObjectFormat()) {
   case Triple::MachO:
     return link_MachO(std::move(G), std::move(Ctx));
   case Triple::ELF:
     return link_ELF(std::move(G), std::move(Ctx));
+  case Triple::COFF:
+    return link_COFF(std::move(G), std::move(Ctx));
   default:
     Ctx->notifyFailed(make_error<JITLinkError>("Unsupported object format"));
   };
 }
 
 } // end namespace jitlink
 } // end namespace llvm

llvm/lib/ExecutionEngine/Orc/ObjectFileInterface.cpp

 //===------ ObjectFileInterface.cpp - MU interface utils for objects ------===//
 //
 // 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/ObjectFileInterface.h"
 #include "llvm/ExecutionEngine/Orc/ELFNixPlatform.h"
 #include "llvm/ExecutionEngine/Orc/MachOPlatform.h"
+#include "llvm/Object/COFF.h"
 #include "llvm/Object/ELFObjectFile.h"
 #include "llvm/Object/MachO.h"
 #include "llvm/Object/ObjectFile.h"
 #include "llvm/Support/Debug.h"
 
 #define DEBUG_TYPE "orc"
 
 namespace llvm {
if (auto SecName = Sec.getName()) {
         break;
       }
     }
   }
 
   return I;
 }
 
+static Expected<MaterializationUnit::Interface>
+getCOFFObjectFileSymbolInfo(ExecutionSession &ES,
+                            const object::COFFObjectFile &Obj) {
+  MaterializationUnit::Interface I;
+
+  for (auto &Sym : Obj.symbols()) {
+    Expected<uint32_t> SymFlagsOrErr = Sym.getFlags();
+    if (!SymFlagsOrErr)
+      // TODO: Test this error.
+      return SymFlagsOrErr.takeError();
+
+    // Skip symbols not defined in this object file.
+    if (*SymFlagsOrErr & object::BasicSymbolRef::SF_Undefined)
+      continue;
+
+    // Skip symbols that are not global.
+    if (!(*SymFlagsOrErr & object::BasicSymbolRef::SF_Global))
+      continue;
+
+    // Skip symbols that have type SF_File.
+    if (auto SymType = Sym.getType()) {
+      if (*SymType == object::SymbolRef::ST_File)
+        continue;
+    } else
+      return SymType.takeError();
+
+    auto Name = Sym.getName();
+    if (!Name)
+      return Name.takeError();
+
+    auto SymFlags = JITSymbolFlags::fromObjectSymbol(Sym);
+    if (!SymFlags)
+      return SymFlags.takeError();
+
+    auto COFFSym = Obj.getCOFFSymbol(Sym);
+    if (!COFFSym.isUndefined() && COFFSym.isExternal()) {
+      *SymFlags |= JITSymbolFlags::Exported;
+    }
+    if (COFFSym.isWeakExternal()) {
+      *SymFlags |= JITSymbolFlags::Weak;
+    }
+
+    I.SymbolFlags[ES.intern(*Name)] = std::move(*SymFlags);
+  }
+
+  // FIXME: handle init symbols
+
+  return I;
+}
+
 Expected<MaterializationUnit::Interface>
 getGenericObjectFileSymbolInfo(ExecutionSession &ES,
                                const object::ObjectFile &Obj) {
   MaterializationUnit::Interface I;
 
   for (auto &Sym : Obj.symbols()) {
     Expected<uint32_t> SymFlagsOrErr = Sym.getFlags();
     if (!SymFlagsOrErr)
getObjectFileInterface(ExecutionSession &ES, MemoryBufferRef ObjBuffer) {
 
   if (!Obj)
     return Obj.takeError();
 
   if (auto *MachOObj = dyn_cast<object::MachOObjectFile>(Obj->get()))
     return getMachOObjectFileSymbolInfo(ES, *MachOObj);
   else if (auto *ELFObj = dyn_cast<object::ELFObjectFileBase>(Obj->get()))
     return getELFObjectFileSymbolInfo(ES, *ELFObj);
+  else if (auto *COFFObj = dyn_cast<object::COFFObjectFile>(Obj->get()))
+    return getCOFFObjectFileSymbolInfo(ES, *COFFObj);
 
   return getGenericObjectFileSymbolInfo(ES, **Obj);
 }
 
 } // End namespace orc.
 } // End namespace llvm.

llvm/test/ExecutionEngine/JITLink/X86/COFF_abs.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check absolute symbol is created with a correct value.
+#
+# CHECK: Creating graph symbols...
+# CHECK:   6: Creating defined graph symbol for COFF symbol "abs" in (absolute) (index: -1)
+# CHECK-NEXT:  0x53 (addressable + 0x00000000): size: 0x00000000, linkage: strong, scope: local, dead  -   abs
+
+  .text
+  .def  abs;
+  .scl  3;
+  .type 0;
+  .endef
+  .globl  abs
+.set abs, 0x53
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main
+  .p2align  4, 0x90
+main:
+  retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_basic.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink -noexec %t
+# 
+# Check a basic COFF object file loads successfully.
+
+  .text
+  .def  @feat.00;
+  .scl  3;
+  .type 0;
+  .endef
+  .globl  @feat.00
+.set @feat.00, 0
+  .file "main.c"
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main
+  .p2align  4, 0x90
+main:
+    .seh_proc main
+  pushq %rax
+  .seh_stackalloc 8
+  .seh_endprologue
+  movl  $0, 4(%rsp)
+  xorl  %eax, %eax
+  popq  %rcx
+  retq
+  .seh_endproc

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_any.test

+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+# 
+# Check a weak symbol is created for a COMDAT symbol with IMAGE_COMDAT_SELECT_ANY selection type.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      2: Creating defined graph symbol for COFF symbol ".text" in .text (index: 2)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: local, dead  -   <anonymous symbol>
+# CHECK-NEXT: 4: Exporting COMDAT graph symbol for COFF symbol "func" in section 2
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: weak, scope: default, dead  -   func
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            .text
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          2
+      Selection:       IMAGE_COMDAT_SELECT_ANY
+  - Name:            func
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_associative.test

+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec --debug-only=jitlink -noexec %t 2>&1
+# 
+# Check COMDAT associative symbol is emitted as local symbol.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      2: Creating defined graph symbol for COFF symbol ".text" in .text (index: 2)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: local, dead  -   <anonymous symbol>
+# CHECK-NEXT: 4: Exporting COMDAT graph symbol for COFF symbol "func" in section 2
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: weak, scope: default, dead  -   func
+# CHECK-NEXT: 5: Creating defined graph symbol for COFF symbol ".xdata" in .xdata (index: 3)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000000, linkage: strong, scope: local, dead  -   .xdata
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+  - Name:            .xdata
+    Characteristics: [ IMAGE_SCN_CNT_INITIALIZED_DATA, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_READ ]
+    Alignment:       4
+    SectionData:     '0100000000000000'
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            .text
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          2
+      Selection:       IMAGE_COMDAT_SELECT_ANY
+  - Name:            func
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            .xdata
+    Value:           0
+    SectionNumber:   3
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          8
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        3433693342
+      Number:          2
+      Selection:       IMAGE_COMDAT_SELECT_ASSOCIATIVE
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_exact_match.test

+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+# 
+# Check a weak symbol is created for a COMDAT symbol with IMAGE_COMDAT_SELECT_EXACT_MATCH selection type.
+# Doesn't check the content validation.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      2: Creating defined graph symbol for COFF symbol ".text" in .text (index: 2)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: local, dead  -   <anonymous symbol>
+# CHECK-NEXT: 4: Exporting COMDAT graph symbol for COFF symbol "func" in section 2
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: weak, scope: default, dead  -   func
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            .text
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          2
+      Selection:       IMAGE_COMDAT_SELECT_EXACT_MATCH
+  - Name:            func
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_largest.test

+# XFAIL: *
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec --debug-only=jitlink -noexec %t 2>&1
+# 
+# Check jitlink return an error when IMAGE_COMDAT_SELECT_LARGEST selection type is encountered.
+#
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            .text
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          2
+      Selection:       IMAGE_COMDAT_SELECT_LARGEST
+  - Name:            func
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_noduplicate.test

+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+# 
+# Check a strong symbol is created for a COMDAT symbol with IMAGE_COMDAT_SELECT_NODUPLICATES selection type.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      2: Creating defined graph symbol for COFF symbol ".text" in .text (index: 2)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: local, dead  -   <anonymous symbol>
+# CHECK-NEXT: 4: Exporting COMDAT graph symbol for COFF symbol "func" in section 2
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: default, dead  -   func
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            .text
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          2
+      Selection:       IMAGE_COMDAT_SELECT_NODUPLICATES
+  - Name:            func
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_same_size.test

+# RUN: yaml2obj %s -o %t
+# RUN: llvm-jitlink -noexec --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+# 
+# Check a weak symbol is created for a COMDAT symbol with IMAGE_COMDAT_SELECT_SAME_SIZE selection type.
+# Doesn't check the size validation.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      2: Creating defined graph symbol for COFF symbol ".text" in .text (index: 2)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: local, dead  -   <anonymous symbol>
+# CHECK-NEXT: 4: Exporting COMDAT graph symbol for COFF symbol "func" in section 2
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: weak, scope: default, dead  -   func
+
+--- !COFF
+header:
+  Machine:         IMAGE_FILE_MACHINE_AMD64
+  Characteristics: [  ]
+sections:
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+  - Name:            .text
+    Characteristics: [ IMAGE_SCN_CNT_CODE, IMAGE_SCN_LNK_COMDAT, IMAGE_SCN_MEM_EXECUTE, IMAGE_SCN_MEM_READ ]
+    Alignment:       16
+    SectionData:     C3
+symbols:
+  - Name:            .text
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          1
+  - Name:            .text
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_NULL
+    StorageClass:    IMAGE_SYM_CLASS_STATIC
+    SectionDefinition:
+      Length:          1
+      NumberOfRelocations: 0
+      NumberOfLinenumbers: 0
+      CheckSum:        40735498
+      Number:          2
+      Selection:       IMAGE_COMDAT_SELECT_SAME_SIZE
+  - Name:            func
+    Value:           0
+    SectionNumber:   2
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+  - Name:            main
+    Value:           0
+    SectionNumber:   1
+    SimpleType:      IMAGE_SYM_TYPE_NULL
+    ComplexType:     IMAGE_SYM_DTYPE_FUNCTION
+    StorageClass:    IMAGE_SYM_CLASS_EXTERNAL
+...

llvm/test/ExecutionEngine/JITLink/X86/COFF_comdat_weak.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check a COMDAT any symbol is exported as a weak symbol.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      6: Creating defined graph symbol for COFF symbol ".text" in .text (index: 4)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: strong, scope: local, dead  -   <anonymous symbol>
+# CHECK-NEXT: 8: Exporting COMDAT graph symbol for COFF symbol "func" in section 4
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000001, linkage: weak, scope: default, dead  -   func
+
+  .text
+
+  .def  func;
+  .scl  2;
+  .type 32;
+  .endef
+  .section  .text,"xr",discard,func
+  .globl  func
+  .p2align  4, 0x90
+func:
+  retq
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .text
+  .globl  main
+  .p2align  4, 0x90
+main:
+  retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_common_symbol.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check a common symbol is created.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      7: Creating defined graph symbol for COFF symbol "var" in (common) (index: 0)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000004, linkage: weak, scope: default, dead  -   var
+
+  .text
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main
+  .p2align  4
+main:
+  movl  var(%rip), %eax
+  retq
+
+  .comm var,4,2

llvm/test/ExecutionEngine/JITLink/X86/COFF_external_func.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink -abs func=0xcafef00d --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check an external symbol to a functon is created.
+#
+# CHECK: Creating graph symbols...
+# CHECK:   7: Creating external graph symbol for COFF symbol "func" in (external) (index: 0)
+
+  .text
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main
+  .p2align  4, 0x90
+main:
+  callq func
+  retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_external_var.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink -abs var=0xcafef00d --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check an external symbol to a variable is created.
+#
+# CHECK: Creating graph symbols...
+# CHECK:   7: Creating external graph symbol for COFF symbol "var" in (external) (index: 0)
+
+  .text
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main 
+  .p2align  4, 0x90
+main:
+  movl  var(%rip), %eax
+  retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_file_debug.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink -abs var=0xcafef00d --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check a file debug symbol is skipped.
+#
+# CHECK: Creating graph symbols...
+# CHECK:   8: Skipping FileRecord symbol ".file" in (debug) (index: -2)
+
+  .text
+
+  .file "skip_this_file_symbol"
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main
+  .p2align  4, 0x90
+main:
+  callq func
+  retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_static_var.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink -abs var=0xcafef00d --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check a local symbol is created for a static variable.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      7: Creating defined graph symbol for COFF symbol "var" in .data (index: 2)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000000, linkage: strong, scope: local, dead  -   var
+
+  .text
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main
+  .p2align  4, 0x90
+main:
+  retq
+
+  .data
+  .p2align  2
+var:
+  .long 53

llvm/test/ExecutionEngine/JITLink/X86/COFF_weak_external.s

+# RUN: llvm-mc -filetype=obj -triple=x86_64-windows-msvc %s -o %t
+# RUN: llvm-jitlink -abs var=0xcafef00d --debug-only=jitlink -noexec %t 2>&1 | FileCheck %s
+#
+# Check a local symbol is aliased as a weak external symbol.
+#
+# CHECK: Creating graph symbols...
+# CHECK:      8: Creating defined graph symbol for COFF symbol ".weak.func.default.main" in .text (index: 1)
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000000, linkage: strong, scope: default, dead  -   .weak.func.default.main 
+# CHECK-NEXT: 9: Creating defined graph symbol for COFF symbol "main" in .text (index: 1)
+# CHECK-NEXT:   0x10 (block + 0x00000010): size: 0x00000000, linkage: strong, scope: default, dead  -   main
+# CHECK-NEXT: 6: Creating weak alias symbol for COFF symbol "func" in section 0
+# CHECK-NEXT:   0x0 (block + 0x00000000): size: 0x00000000, linkage: weak, scope: default, dead  -   func
+
+  .text
+
+  .def  func;
+  .scl  2;
+  .type 32;
+  .endef
+  .weak func
+  .p2align  4, 0x90
+func:
+  retq
+
+  .def  main;
+  .scl  2;
+  .type 32;
+  .endef
+  .globl  main
+  .p2align  4, 0x90
+main:
+  retq

llvm/test/ExecutionEngine/JITLink/X86/COFF_x86-64_small_pic_relocations.s

+# RUN: rm -rf %t && mkdir -p %t
+# RUN: llvm-mc -triple=x86_64-windows-msvc -relax-relocations=false \
+# RUN:   -position-independent -filetype=obj -o %t/coff_sm_reloc.o %s
+# RUN: llvm-jitlink -noexec \
+# RUN:              -slab-allocate 100Kb -slab-address 0xfff00000 -slab-page-size 4096 \
+# RUN:              -abs external_data=0xdeadbeef \
+# RUN:              -abs extern_out_of_range32=0x7fff00000000 \
+# RUN:              -check %s %t/coff_sm_reloc.o
+
+  .text
+
+  .def main;
+  .scl 2;
+  .type 32;
+  .endef
+  .globl main
+  .p2align 4, 0x90
+main:
+  retq
+
+# Check a IMAGE_REL_AMD64_REL32 relocation to local function symbol.
+# jitlink-check: decode_operand(test_rel32_func, 0) = named_func - next_pc(test_rel32_func)
+  .def test_rel32_func;
+  .scl 2;
+  .type 32;
+  .endef
+  .globl test_rel32_func
+  .p2align 4, 0x90
+test_rel32_func:
+  callq named_func
+
+# Check a IMAGE_REL_AMD64_REL32 relocation to local data symbol.
+# jitlink-check: decode_operand(test_rel32_data, 4) = named_data - next_pc(test_rel32_data)
+  .def test_rel32_data;
+  .scl 2;
+  .type 32;
+  .endef
+  .globl test_rel32_data
+  .p2align 4, 0x90
+test_rel32_data:
+    leaq named_data(%rip), %rax
+
+# Check that calls to external functions out-of-range from the callsite trigger 
+# the generation of stubs and GOT entries. This produces a BranchPCRel32 edge, 
+# but STUB table manager will create a STUB sequence because external function 
+# is out-of-range from the callsite.
+#
+# jitlink-check: decode_operand(test_call_extern_out_of_range32, 0) = \
+# jitlink-check:     stub_addr(coff_sm_reloc.o, extern_out_of_range32) - \
+# jitlink-check:        next_pc(test_call_extern_out_of_range32)
+# jitlink-check: *{8}(got_addr(coff_sm_reloc.o, extern_out_of_range32)) = \
+# jitlink-check:     extern_out_of_range32
+  .def test_call_extern_out_of_range32;
+  .scl 2;
+  .type 32;
+  .endef
+  .globl main
+  .p2align 4, 0x90
+test_call_extern_out_of_range32:
+  callq extern_out_of_range32
+  retq
+
+# Local named data/func that is used in conjunction with other test cases
+  .text
+  .def named_func;
+  .scl 2;
+  .type 32;
+  .endef
+  .globl named_func
+  .p2align 4, 0x90
+named_func:
+  retq
+
+  .data
+  .p2align 3
+named_data:
+  .quad 53
+

llvm/tools/llvm-jitlink/CMakeLists.txt

set(LLVM_LINK_COMPONENTS
   OrcShared
   OrcTargetProcess
   RuntimeDyld
   Support
   )
 
 add_llvm_tool(llvm-jitlink
   llvm-jitlink.cpp
+  llvm-jitlink-coff.cpp
   llvm-jitlink-elf.cpp
   llvm-jitlink-macho.cpp
   )
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "Haiku")
   target_link_libraries(llvm-jitlink PRIVATE network)
 endif()
 
 if(${CMAKE_SYSTEM_NAME} MATCHES "SunOS")
   target_link_libraries(llvm-jitlink PRIVATE socket nsl)
 endif()
 
 export_executable_symbols(llvm-jitlink)

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

+//===--- llvm-jitlink-coff.cpp -- COFF parsing support for llvm-jitlink ---===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// COFF parsing support for llvm-jitlink.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm-jitlink.h"
+
+#include "llvm/Support/Error.h"
+#include "llvm/Support/Path.h"
+
+#define DEBUG_TYPE "llvm_jitlink"
+
+using namespace llvm;
+using namespace llvm::jitlink;
+
+static bool isCOFFGOTSection(Section &S) { return S.getName() == "$__GOT"; }
+
+static bool isCOFFStubsSection(Section &S) { return S.getName() == "$__STUBS"; }
+
+static Expected<Edge &> getFirstRelocationEdge(LinkGraph &G, Block &B) {
+  auto EItr = std::find_if(B.edges().begin(), B.edges().end(),
+                           [](Edge &E) { return E.isRelocation(); });
+  if (EItr == B.edges().end())
+    return make_error<StringError>("GOT entry in " + G.getName() + ", \"" +
+                                       B.getSection().getName() +
+                                       "\" has no relocations",
+                                   inconvertibleErrorCode());
+  return *EItr;
+}
+
+static Expected<Symbol &> getCOFFGOTTarget(LinkGraph &G, Block &B) {
+  auto E = getFirstRelocationEdge(G, B);
+  if (!E)
+    return E.takeError();
+  auto &TargetSym = E->getTarget();
+  if (!TargetSym.hasName())
+    return make_error<StringError>(
+        "GOT entry in " + G.getName() + ", \"" +
+            TargetSym.getBlock().getSection().getName() +
+            "\" points to anonymous "
+            "symbol",
+        inconvertibleErrorCode());
+  return TargetSym;
+}
+
+static Expected<Symbol &> getCOFFStubTarget(LinkGraph &G, Block &B) {
+  auto E = getFirstRelocationEdge(G, B);
+  if (!E)
+    return E.takeError();
+  auto &GOTSym = E->getTarget();
+  if (!GOTSym.isDefined() || !isCOFFGOTSection(GOTSym.getBlock().getSection()))
+    return make_error<StringError>(
+        "Stubs entry in " + G.getName() + ", \"" +
+            GOTSym.getBlock().getSection().getName() +
+            "\" does not point to GOT entry",
+        inconvertibleErrorCode());
+  return getCOFFGOTTarget(G, GOTSym.getBlock());
+}
+
+namespace llvm {
+Error registerCOFFGraphInfo(Session &S, LinkGraph &G) {
+  auto FileName = sys::path::filename(G.getName());
+  if (S.FileInfos.count(FileName)) {
+    return make_error<StringError>("When -check is passed, file names must be "
+                                   "distinct (duplicate: \"" +
+                                       FileName + "\")",
+                                   inconvertibleErrorCode());
+  }
+
+  auto &FileInfo = S.FileInfos[FileName];
+  LLVM_DEBUG(
+      { dbgs() << "Registering COFF file info for \"" << FileName << "\"\n"; });
+  for (auto &Sec : G.sections()) {
+    LLVM_DEBUG({
+      dbgs() << "  Section \"" << Sec.getName() << "\": "
+             << (llvm::empty(Sec.symbols()) ? "empty. skipping."
+                                            : "processing...")
+             << "\n";
+    });
+
+    // Skip empty sections.
+    if (llvm::empty(Sec.symbols()))
+      continue;
+
+    if (FileInfo.SectionInfos.count(Sec.getName()))
+      return make_error<StringError>("Encountered duplicate section name \"" +
+                                         Sec.getName() + "\" in \"" + FileName +
+                                         "\"",
+                                     inconvertibleErrorCode());
+
+    bool isGOTSection = isCOFFGOTSection(Sec);
+    bool isStubsSection = isCOFFStubsSection(Sec);
+
+    bool SectionContainsContent = false;
+    bool SectionContainsZeroFill = false;
+
+    auto *FirstSym = *Sec.symbols().begin();
+    auto *LastSym = FirstSym;
+    for (auto *Sym : Sec.symbols()) {
+      if (Sym->getAddress() < FirstSym->getAddress())
+        FirstSym = Sym;
+      if (Sym->getAddress() > LastSym->getAddress())
+        LastSym = Sym;
+
+      if (isGOTSection) {
+        if (Sym->isSymbolZeroFill())
+          return make_error<StringError>("zero-fill atom in GOT section",
+                                         inconvertibleErrorCode());
+
+        // If this is a GOT symbol with size (i.e. not the GOT start symbol)
+        // then add it to the GOT entry info table.
+        if (Sym->getSize() != 0) {
+          if (auto TS = getCOFFGOTTarget(G, Sym->getBlock()))
+            FileInfo.GOTEntryInfos[TS->getName()] = {
+                Sym->getSymbolContent(), Sym->getAddress().getValue()};
+          else
+            return TS.takeError();
+        }
+        SectionContainsContent = true;
+      } else if (isStubsSection) {
+        if (Sym->isSymbolZeroFill())
+          return make_error<StringError>("zero-fill atom in Stub section",
+                                         inconvertibleErrorCode());
+
+        if (auto TS = getCOFFStubTarget(G, Sym->getBlock()))
+          FileInfo.StubInfos[TS->getName()] = {Sym->getSymbolContent(),
+                                               Sym->getAddress().getValue()};
+        else
+          return TS.takeError();
+        SectionContainsContent = true;
+      }
+
+      if (Sym->hasName()) {
+        if (Sym->isSymbolZeroFill()) {
+          S.SymbolInfos[Sym->getName()] = {Sym->getSize(),
+                                           Sym->getAddress().getValue()};
+          SectionContainsZeroFill = true;
+        } else {
+          S.SymbolInfos[Sym->getName()] = {Sym->getSymbolContent(),
+                                           Sym->getAddress().getValue()};
+          SectionContainsContent = true;
+        }
+      }
+    }
+
+    auto SecAddr = FirstSym->getAddress();
+    auto SecSize =
+        (LastSym->getBlock().getAddress() + LastSym->getBlock().getSize()) -
+        SecAddr;
+
+    if (SectionContainsZeroFill && SectionContainsContent)
+      return make_error<StringError>("Mixed zero-fill and content sections not "
+                                     "supported yet",
+                                     inconvertibleErrorCode());
+
+    if (SectionContainsZeroFill)
+      FileInfo.SectionInfos[Sec.getName()] = {SecSize, SecAddr.getValue()};
+    else
+      FileInfo.SectionInfos[Sec.getName()] = {
+          ArrayRef<char>(FirstSym->getBlock().getContent().data(), SecSize),
+          SecAddr.getValue()};
+  }
+
+  return Error::success();
+}
+
+} // end namespace llvm

llvm/tools/llvm-jitlink/llvm-jitlink.h

 };
 
 /// Record symbols, GOT entries, stubs, and sections for ELF file.
 Error registerELFGraphInfo(Session &S, jitlink::LinkGraph &G);
 
 /// Record symbols, GOT entries, stubs, and sections for MachO file.
 Error registerMachOGraphInfo(Session &S, jitlink::LinkGraph &G);
 
+/// Record symbols, GOT entries, stubs, and sections for COFF file.
+Error registerCOFFGraphInfo(Session &S, jitlink::LinkGraph &G);
+
 } // end namespace llvm
 
 #endif // LLVM_TOOLS_LLVM_JITLINK_LLVM_JITLINK_H

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

Session::Session(std::unique_ptr<ExecutorProcessControl> EPC, Error &Err)
   } else if (TT.isOSBinFormatELF() && !OrcRuntime.empty()) {
     if (auto P =
             ELFNixPlatform::Create(ES, ObjLayer, *MainJD, OrcRuntime.c_str()))
       ES.setPlatform(std::move(*P));
     else {
       Err = P.takeError();
       return;
     }
-  } else if (!TT.isOSWindows() && !TT.isOSBinFormatMachO()) {
+  } else if (TT.isOSBinFormatELF()) {
     if (!NoExec)
       ObjLayer.addPlugin(std::make_unique<EHFrameRegistrationPlugin>(
           ES, ExitOnErr(EPCEHFrameRegistrar::Create(this->ES))));
     if (DebuggerSupport)
       ObjLayer.addPlugin(std::make_unique<DebugObjectManagerPlugin>(
           ES, ExitOnErr(createJITLoaderGDBRegistrar(this->ES))));
   }
 
if (!CheckFiles.empty())
     PassConfig.PostFixupPasses.push_back([this](LinkGraph &G) {
       auto &EPC = ES.getExecutorProcessControl();
       if (EPC.getTargetTriple().getObjectFormat() == Triple::ELF)
         return registerELFGraphInfo(*this, G);
 
       if (EPC.getTargetTriple().getObjectFormat() == Triple::MachO)
         return registerMachOGraphInfo(*this, G);
 
+      if (EPC.getTargetTriple().isOSWindows())
+        return registerCOFFGraphInfo(*this, G);
+
       return make_error<StringError>("Unsupported object format for GOT/stub "
                                      "registration",
                                      inconvertibleErrorCode());
     });
 
   if (ShowLinkGraph)
     PassConfig.PostFixupPasses.push_back([](LinkGraph &G) -> Error {
       outs() << "Link graph \"" << G.getName() << "\" post-fixup:\n";

 
 } // end namespace llvm
 
 static Triple getFirstFileTriple() {
   static Triple FirstTT = []() {
     assert(!InputFiles.empty() && "InputFiles can not be empty");
     for (auto InputFile : InputFiles) {
       auto ObjBuffer = ExitOnErr(getFile(InputFile));
-      switch (identify_magic(ObjBuffer->getBuffer())) {
+      file_magic Magic = identify_magic(ObjBuffer->getBuffer());
+      switch (Magic) {
+      case file_magic::coff_object:
       case file_magic::elf_relocatable:
-      case file_magic::macho_object:
-      case file_magic::coff_object: {
+      case file_magic::macho_object: {
         auto Obj = ExitOnErr(
             object::ObjectFile::createObjectFile(ObjBuffer->getMemBufferRef()));
-        return Obj->makeTriple();
+        Triple TT = Obj->makeTriple();
+        if (Magic == file_magic::coff_object)
+          TT.setOS(Triple::OSType::Win32);
+        return TT;
       }
       default:
         break;
       }
     }
     return Triple();
   }();