Boilerplate for producing XCOFF object files from the PowerPC backend.

Stubs out a number of the classes needed to produce a new object file format
(XCOFF) for the powerpc-aix target. For testing input is an empty module which
produces an object file with just a file header.

Differential Revision: https://reviews.llvm.org/D61694

llvm-svn: 365541
diff --git a/llvm/lib/MC/CMakeLists.txt b/llvm/lib/MC/CMakeLists.txt
index ba36d99..14e965b 100644
--- a/llvm/lib/MC/CMakeLists.txt
+++ b/llvm/lib/MC/CMakeLists.txt
@@ -7,6 +7,7 @@
   MCAsmInfoDarwin.cpp
   MCAsmInfoELF.cpp
   MCAsmInfoWasm.cpp
+  MCAsmInfoXCOFF.cpp
   MCAsmMacro.cpp
   MCAsmStreamer.cpp
   MCAssembler.cpp
@@ -38,6 +39,7 @@
   MCSectionELF.cpp
   MCSectionMachO.cpp
   MCSectionWasm.cpp
+  MCSectionXCOFF.cpp
   MCStreamer.cpp
   MCSubtargetInfo.cpp
   MCSymbol.cpp
@@ -49,11 +51,14 @@
   MCWin64EH.cpp
   MCWinCOFFStreamer.cpp
   MCWinEH.cpp
+  MCXCOFFObjectTargetWriter.cpp
+  MCXCOFFStreamer.cpp
   MachObjectWriter.cpp
   StringTableBuilder.cpp
   SubtargetFeature.cpp
   WasmObjectWriter.cpp
   WinCOFFObjectWriter.cpp
+  XCOFFObjectWriter.cpp
 
   ADDITIONAL_HEADER_DIRS
   ${LLVM_MAIN_INCLUDE_DIR}/llvm/MC
diff --git a/llvm/lib/MC/MCAsmBackend.cpp b/llvm/lib/MC/MCAsmBackend.cpp
index 912bec9..9b1102c 100644
--- a/llvm/lib/MC/MCAsmBackend.cpp
+++ b/llvm/lib/MC/MCAsmBackend.cpp
@@ -16,6 +16,7 @@
 #include "llvm/MC/MCObjectWriter.h"
 #include "llvm/MC/MCWasmObjectWriter.h"
 #include "llvm/MC/MCWinCOFFObjectWriter.h"
+#include "llvm/MC/MCXCOFFObjectWriter.h"
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
@@ -43,6 +44,9 @@
   case Triple::Wasm:
     return createWasmObjectWriter(cast<MCWasmObjectTargetWriter>(std::move(TW)),
                                   OS);
+  case Triple::XCOFF:
+    return createXCOFFObjectWriter(
+        cast<MCXCOFFObjectTargetWriter>(std::move(TW)), OS);
   default:
     llvm_unreachable("unexpected object format");
   }
diff --git a/llvm/lib/MC/MCAsmInfoXCOFF.cpp b/llvm/lib/MC/MCAsmInfoXCOFF.cpp
new file mode 100644
index 0000000..74c21f0
--- /dev/null
+++ b/llvm/lib/MC/MCAsmInfoXCOFF.cpp
@@ -0,0 +1,18 @@
+//===- MC/MCAsmInfoXCOFF.cpp - XCOFF asm properties ------------ *- 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCAsmInfoXCOFF.h"
+
+using namespace llvm;
+
+void MCAsmInfoXCOFF::anchor() {}
+
+MCAsmInfoXCOFF::MCAsmInfoXCOFF() {
+  IsLittleEndian = false;
+  HasDotTypeDotSizeDirective = false;
+}
diff --git a/llvm/lib/MC/MCContext.cpp b/llvm/lib/MC/MCContext.cpp
index 5ec03ee..0dc2e2d 100644
--- a/llvm/lib/MC/MCContext.cpp
+++ b/llvm/lib/MC/MCContext.cpp
@@ -26,6 +26,7 @@
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCSectionWasm.h"
+#include "llvm/MC/MCSectionXCOFF.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCSymbolCOFF.h"
@@ -86,6 +87,7 @@
   COFFAllocator.DestroyAll();
   ELFAllocator.DestroyAll();
   MachOAllocator.DestroyAll();
+  XCOFFAllocator.DestroyAll();
 
   MCSubtargetAllocator.DestroyAll();
   UsedNames.clear();
@@ -107,6 +109,7 @@
   ELFUniquingMap.clear();
   COFFUniquingMap.clear();
   WasmUniquingMap.clear();
+  XCOFFUniquingMap.clear();
 
   NextID.clear();
   AllowTemporaryLabels = true;
@@ -526,6 +529,38 @@
   return Result;
 }
 
+MCSectionXCOFF *MCContext::getXCOFFSection(StringRef Section,
+                                           XCOFF::StorageMappingClass SMC,
+                                           SectionKind Kind,
+                                           const char *BeginSymName) {
+  // Do the lookup. If we have a hit, return it.
+  auto IterBool = XCOFFUniquingMap.insert(
+      std::make_pair(XCOFFSectionKey{Section.str(), SMC}, nullptr));
+  auto &Entry = *IterBool.first;
+  if (!IterBool.second)
+    return Entry.second;
+
+  // Otherwise, return a new section.
+  StringRef CachedName = Entry.first.SectionName;
+
+  MCSymbol *Begin = nullptr;
+  if (BeginSymName)
+    Begin = createTempSymbol(BeginSymName, false);
+
+  MCSectionXCOFF *Result = new (XCOFFAllocator.Allocate())
+      MCSectionXCOFF(CachedName, SMC, Kind, Begin);
+  Entry.second = Result;
+
+  auto *F = new MCDataFragment();
+  Result->getFragmentList().insert(Result->begin(), F);
+  F->setParent(Result);
+
+  if (Begin)
+    Begin->setFragment(F);
+
+  return Result;
+}
+
 MCSubtargetInfo &MCContext::getSubtargetCopy(const MCSubtargetInfo &STI) {
   return *new (MCSubtargetAllocator.Allocate()) MCSubtargetInfo(STI);
 }
diff --git a/llvm/lib/MC/MCObjectFileInfo.cpp b/llvm/lib/MC/MCObjectFileInfo.cpp
index 0faa236..9f555ab 100644
--- a/llvm/lib/MC/MCObjectFileInfo.cpp
+++ b/llvm/lib/MC/MCObjectFileInfo.cpp
@@ -18,6 +18,7 @@
 #include "llvm/MC/MCSectionELF.h"
 #include "llvm/MC/MCSectionMachO.h"
 #include "llvm/MC/MCSectionWasm.h"
+#include "llvm/MC/MCSectionXCOFF.h"
 
 using namespace llvm;
 
@@ -761,6 +762,15 @@
   // TODO: Define more sections.
 }
 
+void MCObjectFileInfo::initXCOFFMCObjectFileInfo(const Triple &T) {
+  // The default csect for program code. Functions without a specified section
+  // get placed into this csect. The choice of csect name is not a property of
+  // the ABI or object file format. For example, the XL compiler uses an unnamed
+  // csect for program code.
+  TextSection = Ctx->getXCOFFSection(
+      ".text", XCOFF::StorageMappingClass::XMC_PR, SectionKind::getText());
+}
+
 void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple, bool PIC,
                                             MCContext &ctx,
                                             bool LargeCodeModel) {
@@ -809,8 +819,7 @@
     break;
   case Triple::XCOFF:
     Env = IsXCOFF;
-    // TODO: Initialize MCObjectFileInfo for XCOFF format when
-    // MCSectionXCOFF is ready.
+    initXCOFFMCObjectFileInfo(TT);
     break;
   case Triple::UnknownObjectFormat:
     report_fatal_error("Cannot initialize MC for unknown object file format.");
diff --git a/llvm/lib/MC/MCSectionXCOFF.cpp b/llvm/lib/MC/MCSectionXCOFF.cpp
new file mode 100644
index 0000000..d1a6373
--- /dev/null
+++ b/llvm/lib/MC/MCSectionXCOFF.cpp
@@ -0,0 +1,33 @@
+//===- lib/MC/MCSectionXCOFF.cpp - XCOFF Code Section Representation ------===//
+//
+// 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/MC/MCSectionXCOFF.h"
+#include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/Support/raw_ostream.h"
+
+using namespace llvm;
+
+MCSectionXCOFF::~MCSectionXCOFF() = default;
+
+void MCSectionXCOFF::PrintSwitchToSection(const MCAsmInfo &MAI, const Triple &T,
+                                          raw_ostream &OS,
+                                          const MCExpr *Subsection) const {
+  if (getKind().isText()) {
+    OS << "\t.csect " << getSectionName() << "["
+       << "PR"
+       << "]" << '\n';
+    return;
+  }
+
+  report_fatal_error("Printing for this SectionKind is unimplemented.");
+}
+
+bool MCSectionXCOFF::UseCodeAlign() const { return getKind().isText(); }
+
+bool MCSectionXCOFF::isVirtualSection() const { return !getKind().isCommon(); }
diff --git a/llvm/lib/MC/MCXCOFFObjectTargetWriter.cpp b/llvm/lib/MC/MCXCOFFObjectTargetWriter.cpp
new file mode 100644
index 0000000..504e333
--- /dev/null
+++ b/llvm/lib/MC/MCXCOFFObjectTargetWriter.cpp
@@ -0,0 +1,16 @@
+//===- MCXCOFFObjectTargetWriter.cpp - XCOFF Target Writer Subclass -------===//
+//
+// 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/MC/MCXCOFFObjectWriter.h"
+
+using namespace llvm;
+
+MCXCOFFObjectTargetWriter::MCXCOFFObjectTargetWriter(bool Is64Bit)
+    : Is64Bit(Is64Bit) {}
+
+MCXCOFFObjectTargetWriter::~MCXCOFFObjectTargetWriter() = default;
diff --git a/llvm/lib/MC/MCXCOFFStreamer.cpp b/llvm/lib/MC/MCXCOFFStreamer.cpp
new file mode 100644
index 0000000..071de02
--- /dev/null
+++ b/llvm/lib/MC/MCXCOFFStreamer.cpp
@@ -0,0 +1,59 @@
+//===- lib/MC/MCXCOFFStreamer.cpp - XCOFF Object Output -------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file assembles .s files and emits XCOFF .o object files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCXCOFFStreamer.h"
+#include "llvm/MC/MCAsmBackend.h"
+#include "llvm/MC/MCCodeEmitter.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/Support/TargetRegistry.h"
+
+using namespace llvm;
+
+MCXCOFFStreamer::MCXCOFFStreamer(MCContext &Context,
+                                 std::unique_ptr<MCAsmBackend> MAB,
+                                 std::unique_ptr<MCObjectWriter> OW,
+                                 std::unique_ptr<MCCodeEmitter> Emitter)
+    : MCObjectStreamer(Context, std::move(MAB), std::move(OW),
+                       std::move(Emitter)) {}
+
+bool MCXCOFFStreamer::EmitSymbolAttribute(MCSymbol *Symbol,
+                                          MCSymbolAttr Attribute) {
+  report_fatal_error("Symbol attributes not implemented for XCOFF.");
+}
+
+void MCXCOFFStreamer::EmitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
+                                       unsigned ByteAlignment) {
+  report_fatal_error("Emiting common symbols not implemented for XCOFF.");
+}
+
+void MCXCOFFStreamer::EmitZerofill(MCSection *Section, MCSymbol *Symbol,
+                                   uint64_t Size, unsigned ByteAlignment,
+                                   SMLoc Loc) {
+  report_fatal_error("Zero fill not implemented for XCOFF.");
+}
+
+void MCXCOFFStreamer::EmitInstToData(const MCInst &Inst,
+                                     const MCSubtargetInfo &) {
+  report_fatal_error("Instruction emission not implemented for XCOFF.");
+}
+
+MCStreamer *llvm::createXCOFFStreamer(MCContext &Context,
+                                      std::unique_ptr<MCAsmBackend> &&MAB,
+                                      std::unique_ptr<MCObjectWriter> &&OW,
+                                      std::unique_ptr<MCCodeEmitter> &&CE,
+                                      bool RelaxAll) {
+  MCXCOFFStreamer *S = new MCXCOFFStreamer(Context, std::move(MAB),
+                                           std::move(OW), std::move(CE));
+  if (RelaxAll)
+    S->getAssembler().setRelaxAll(true);
+  return S;
+}
diff --git a/llvm/lib/MC/XCOFFObjectWriter.cpp b/llvm/lib/MC/XCOFFObjectWriter.cpp
new file mode 100644
index 0000000..ea586d6
--- /dev/null
+++ b/llvm/lib/MC/XCOFFObjectWriter.cpp
@@ -0,0 +1,94 @@
+//===-- lib/MC/XCOFFObjectWriter.cpp - XCOFF file writer ------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements XCOFF object file writer information.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/MC/MCAssembler.h"
+#include "llvm/MC/MCObjectWriter.h"
+#include "llvm/MC/MCValue.h"
+#include "llvm/MC/MCXCOFFObjectWriter.h"
+
+using namespace llvm;
+
+namespace {
+
+class XCOFFObjectWriter : public MCObjectWriter {
+  support::endian::Writer W;
+  std::unique_ptr<MCXCOFFObjectTargetWriter> TargetObjectWriter;
+
+  void executePostLayoutBinding(MCAssembler &, const MCAsmLayout &) override;
+
+  void recordRelocation(MCAssembler &, const MCAsmLayout &, const MCFragment *,
+                        const MCFixup &, MCValue, uint64_t &) override;
+
+  uint64_t writeObject(MCAssembler &, const MCAsmLayout &) override;
+
+public:
+  XCOFFObjectWriter(std::unique_ptr<MCXCOFFObjectTargetWriter> MOTW,
+                    raw_pwrite_stream &OS);
+};
+
+XCOFFObjectWriter::XCOFFObjectWriter(
+    std::unique_ptr<MCXCOFFObjectTargetWriter> MOTW, raw_pwrite_stream &OS)
+    : W(OS, support::big), TargetObjectWriter(std::move(MOTW)) {}
+
+void XCOFFObjectWriter::executePostLayoutBinding(MCAssembler &,
+                                                 const MCAsmLayout &) {
+  // TODO Implement once we have sections and symbols to handle.
+}
+
+void XCOFFObjectWriter::recordRelocation(MCAssembler &, const MCAsmLayout &,
+                                         const MCFragment *, const MCFixup &,
+                                         MCValue, uint64_t &) {
+  report_fatal_error("XCOFF relocations not supported.");
+}
+
+uint64_t XCOFFObjectWriter::writeObject(MCAssembler &Asm, const MCAsmLayout &) {
+  // We always emit a timestamp of 0 for reproducibility, so ensure incremental
+  // linking is not enabled, in case, like with Windows COFF, such a timestamp
+  // is incompatible with incremental linking of XCOFF.
+  if (Asm.isIncrementalLinkerCompatible())
+    report_fatal_error("Incremental linking not supported for XCOFF.");
+
+  if (TargetObjectWriter->is64Bit())
+    report_fatal_error("64-bit XCOFF object files are not supported yet.");
+
+  uint64_t StartOffset = W.OS.tell();
+
+  // TODO FIXME Assign section numbers/finalize sections.
+
+  // TODO FIXME Finalize symbols.
+
+  // Magic.
+  W.write<uint16_t>(0x01df);
+  // Number of sections.
+  W.write<uint16_t>(0);
+  // Timestamp field. For reproducible output we write a 0, which represents no
+  // timestamp.
+  W.write<int32_t>(0);
+  // Byte Offset to the start of the symbol table.
+  W.write<uint32_t>(0);
+  // Number of entries in the symbol table.
+  W.write<int32_t>(0);
+  // Size of the optional header.
+  W.write<uint16_t>(0);
+  // Flags.
+  W.write<uint16_t>(0);
+
+  return W.OS.tell() - StartOffset;
+}
+
+} // end anonymous namespace
+
+std::unique_ptr<MCObjectWriter>
+llvm::createXCOFFObjectWriter(std::unique_ptr<MCXCOFFObjectTargetWriter> MOTW,
+                              raw_pwrite_stream &OS) {
+  return make_unique<XCOFFObjectWriter>(std::move(MOTW), OS);
+}
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/CMakeLists.txt b/llvm/lib/Target/PowerPC/MCTargetDesc/CMakeLists.txt
index 147e0ef..5a2f605 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/CMakeLists.txt
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/CMakeLists.txt
@@ -8,4 +8,5 @@
   PPCPredicates.cpp
   PPCMachObjectWriter.cpp
   PPCELFObjectWriter.cpp
+  PPCXCOFFObjectWriter.cpp
   )
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
index ec4eb70..8778e91 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCAsmBackend.cpp
@@ -229,6 +229,17 @@
   Optional<MCFixupKind> getFixupKind(StringRef Name) const override;
 };
 
+class XCOFFPPCAsmBackend : public PPCAsmBackend {
+public:
+  XCOFFPPCAsmBackend(const Target &T, const Triple &TT)
+      : PPCAsmBackend(T, TT) {}
+
+  std::unique_ptr<MCObjectTargetWriter>
+  createObjectTargetWriter() const override {
+    return createPPCXCOFFObjectWriter(TT.isArch64Bit());
+  }
+};
+
 } // end anonymous namespace
 
 Optional<MCFixupKind> ELFPPCAsmBackend::getFixupKind(StringRef Name) const {
@@ -250,5 +261,8 @@
   if (TT.isOSDarwin())
     return new DarwinPPCAsmBackend(T, TT);
 
+  if (TT.isOSBinFormatXCOFF())
+    return new XCOFFPPCAsmBackend(T, TT);
+
   return new ELFPPCAsmBackend(T, TT);
 }
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp
index b9e35124..5f0005e 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.cpp
@@ -81,3 +81,9 @@
   UseIntegratedAssembler = true;
 }
 
+void PPCXCOFFMCAsmInfo::anchor() {}
+
+PPCXCOFFMCAsmInfo::PPCXCOFFMCAsmInfo(bool Is64Bit, const Triple &T) {
+  assert(!IsLittleEndian && "Little-endian XCOFF not supported.");
+  CodePointerSize = CalleeSaveStackSlotSize = Is64Bit ? 8 : 4;
+}
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.h b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.h
index 6a10b6e..42cb62a 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.h
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCAsmInfo.h
@@ -6,7 +6,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This file contains the declaration of the MCAsmInfoDarwin class.
+// This file contains the declarations of the PowerPC MCAsmInfo classes.
 //
 //===----------------------------------------------------------------------===//
 
@@ -15,6 +15,7 @@
 
 #include "llvm/MC/MCAsmInfoDarwin.h"
 #include "llvm/MC/MCAsmInfoELF.h"
+#include "llvm/MC/MCAsmInfoXCOFF.h"
 
 namespace llvm {
 class Triple;
@@ -33,6 +34,13 @@
   explicit PPCELFMCAsmInfo(bool is64Bit, const Triple &);
 };
 
+class PPCXCOFFMCAsmInfo : public MCAsmInfoXCOFF {
+  virtual void anchor();
+
+public:
+  explicit PPCXCOFFMCAsmInfo(bool is64Bit, const Triple &);
+};
+
 } // namespace llvm
 
 #endif
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
index c980d27..90c3c8d 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.cpp
@@ -83,6 +83,8 @@
   MCAsmInfo *MAI;
   if (TheTriple.isOSDarwin())
     MAI = new PPCMCAsmInfoDarwin(isPPC64, TheTriple);
+  else if (TheTriple.isOSBinFormatXCOFF())
+    MAI = new PPCXCOFFMCAsmInfo(isPPC64, TheTriple);
   else
     MAI = new PPCELFMCAsmInfo(isPPC64, TheTriple);
 
@@ -235,6 +237,27 @@
   }
 };
 
+class PPCTargetXCOFFStreamer : public PPCTargetStreamer {
+public:
+  PPCTargetXCOFFStreamer(MCStreamer &S) : PPCTargetStreamer(S) {}
+
+  void emitTCEntry(const MCSymbol &S) override {
+    report_fatal_error("TOC entries not supported yet.");
+  }
+
+  void emitMachine(StringRef CPU) override {
+    llvm_unreachable("Machine pseudo-ops are invalid for XCOFF.");
+  }
+
+  void emitAbiVersion(int AbiVersion) override {
+    llvm_unreachable("ABI-version pseudo-ops are invalid for XCOFF.");
+  }
+
+  void emitLocalEntry(MCSymbolELF *S, const MCExpr *LocalOffset) override {
+    llvm_unreachable("Local-entry pseudo-ops are invalid for XCOFF.");
+  }
+};
+
 } // end anonymous namespace
 
 static MCTargetStreamer *createAsmTargetStreamer(MCStreamer &S,
@@ -249,6 +272,8 @@
   const Triple &TT = STI.getTargetTriple();
   if (TT.isOSBinFormatELF())
     return new PPCTargetELFStreamer(S);
+  if (TT.isOSBinFormatXCOFF())
+    return new PPCTargetXCOFFStreamer(S);
   return new PPCTargetMachOStreamer(S);
 }
 
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.h b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.h
index 4829fed..74b67bd 100644
--- a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.h
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCMCTargetDesc.h
@@ -51,6 +51,9 @@
 std::unique_ptr<MCObjectTargetWriter>
 createPPCMachObjectWriter(bool Is64Bit, uint32_t CPUType, uint32_t CPUSubtype);
 
+/// Construct a PPC XCOFF object writer.
+std::unique_ptr<MCObjectTargetWriter> createPPCXCOFFObjectWriter(bool Is64Bit);
+
 /// Returns true iff Val consists of one contiguous run of 1s with any number of
 /// 0s on either side.  The 1s are allowed to wrap from LSB to MSB, so
 /// 0x000FFF0, 0x0000FFFF, and 0xFF0000FF are all runs.  0x0F0F0000 is not,
diff --git a/llvm/lib/Target/PowerPC/MCTargetDesc/PPCXCOFFObjectWriter.cpp b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCXCOFFObjectWriter.cpp
new file mode 100644
index 0000000..9c66128
--- /dev/null
+++ b/llvm/lib/Target/PowerPC/MCTargetDesc/PPCXCOFFObjectWriter.cpp
@@ -0,0 +1,29 @@
+//===-- PPCXCOFFObjectWriter.cpp - PowerPC XCOFF Writer -------------------===//
+//
+//
+// 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 "PPCMCTargetDesc.h"
+#include "llvm/MC/MCXCOFFObjectWriter.h"
+
+using namespace llvm;
+
+namespace {
+class PPCXCOFFObjectWriter : public MCXCOFFObjectTargetWriter {
+
+public:
+  PPCXCOFFObjectWriter(bool Is64Bit);
+};
+} // end anonymous namespace
+
+PPCXCOFFObjectWriter::PPCXCOFFObjectWriter(bool Is64Bit)
+    : MCXCOFFObjectTargetWriter(Is64Bit) {}
+
+std::unique_ptr<MCObjectTargetWriter>
+llvm::createPPCXCOFFObjectWriter(bool Is64Bit) {
+  return llvm::make_unique<PPCXCOFFObjectWriter>(Is64Bit);
+}
diff --git a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
index 0d8c848..bd87ce0 100644
--- a/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
+++ b/llvm/lib/Target/PowerPC/PPCAsmPrinter.cpp
@@ -158,6 +158,14 @@
   void EmitStartOfAsmFile(Module &M) override;
 };
 
+class PPCAIXAsmPrinter : public PPCAsmPrinter {
+public:
+  PPCAIXAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
+      : PPCAsmPrinter(TM, std::move(Streamer)) {}
+
+  StringRef getPassName() const override { return "AIX PPC Assembly Printer"; }
+};
+
 } // end anonymous namespace
 
 void PPCAsmPrinter::PrintSymbolOperand(const MachineOperand &MO,
@@ -1644,6 +1652,9 @@
                         std::unique_ptr<MCStreamer> &&Streamer) {
   if (tm.getTargetTriple().isMacOSX())
     return new PPCDarwinAsmPrinter(tm, std::move(Streamer));
+  if (tm.getTargetTriple().isOSAIX())
+    return new PPCAIXAsmPrinter(tm, std::move(Streamer));
+
   return new PPCLinuxAsmPrinter(tm, std::move(Streamer));
 }