[PPC][GlobalISel] Add initial GlobalIsel infrastructure

[kbarton]

Summary

This adds the initial GlobalISel skeleton for PowerPC. It can only run
ir-translator and legalizer for ret void.

This is largely based on the initial GlobalISel patch for RISCV
(https://reviews.llvm.org/D65219).

[arsenm]

llvm/lib/Target/PowerPC/PPC.h

88–89

These should be const?

llvm/lib/Target/PowerPC/PPCInstructionSelector.cpp

39 ↗

(On Diff #275251)

I'm pretty sure you don't need these and all the other places that override this are dead code

[kbarton]

Add const to all parameters of createPPCInstructionSelector.

[kbarton]

Refreshing diff.

[kbarton]

Refreshing diff

[kbarton]

I had some problems refreshing the patch using arcanist. I *think* I have fixed everything now, but if things look odd please let me know.

llvm/lib/Target/PowerPC/PPC.h

88–89

Yup, thanks for catching this. Fixed.

llvm/lib/Target/PowerPC/PPCInstructionSelector.cpp

39 ↗

(On Diff #275251)

I don't follow this.
Both select and getName seem to be required - getName is needed by the base InstructionSelector implementation in GlobalISel; select is needed by the PPCGenGlobalISel.inc file generated below.

It is entirely possible I'm doing something incorrect though. Could you explain some more?

[tschuett]

AArch64 has a sub-directory for GlobalISel related things:
https://reviews.llvm.org/D81116

[madhur13490]

llvm/lib/Target/PowerPC/PPCCallLowering.cpp

42 ↗

(On Diff #275412)

Why not do "return VRegs.empty()"? You can add a comment if it needs readability.

llvm/lib/Target/PowerPC/PPCInstructionSelector.cpp

23 ↗

(On Diff #275412)

May be ppc-gisel better?

[tschuett]

llvm/lib/Target/PowerPC/PPCLegalizerInfo.h

21 ↗

(On Diff #275412)

Legalizer or register banks?

[arsenm]

llvm/lib/Target/PowerPC/PPCInstructionSelector.cpp

39 ↗

(On Diff #275251)

Oh right, this isn't the direct pass. I think manual getName overrides are dead code on passes and set by the INITIALIZE_PASS* macros

[kbarton]

• Address review comments - minor clean in PPC::lowerFormalArguments and update comments.

[kbarton]

In D83100#2130726, @tschuett wrote:

AArch64 has a sub-directory for GlobalISel related things:
https://reviews.llvm.org/D81116

I like this idea. I will do the refactoring in a subsequent commit and update the patch, so if others do not like it it's easy to undo.

llvm/lib/Target/PowerPC/PPCInstructionSelector.cpp

23 ↗

(On Diff #275412)

Yes, this is a better idea. Will change it.

39 ↗

(On Diff #275251)

Yes, that could be. I haven't looked at the implementation for how it works on passes.

Are you OK marking this as done?

llvm/lib/Target/PowerPC/PPCLegalizerInfo.h

21 ↗

(On Diff #275412)

Good catch. Updated to legalizer.

[arsenm]

In D83100#2134028, @kbarton wrote:

In D83100#2130726, @tschuett wrote:

AArch64 has a sub-directory for GlobalISel related things:
https://reviews.llvm.org/D81116

I like this idea. I will do the refactoring in a subsequent commit and update the patch, so if others do not like it it's easy to undo.

I don't particularly like the AArch64 split. There isn't an entirely clean break between globalisel parts and the rest of the backend. The other target subdirectories are used for places where there's a separate library

[kbarton]

• Put all new GlobalISel related files into new GISel subdirectory.

[tschuett]

Pardon my cmake, but don't you need a CMakeLists.txt in the GISel sub-directory?

[kbarton]

In D83100#2134249, @tschuett wrote:

Pardon my cmake, but don't you need a CMakeLists.txt in the GISel sub-directory?

I thought I would too, but I added GISel/ prefix to the CMake in the PowerPC directory, which works.
This is the way it was done in the Aarch64 patch that did the refactoring.

That said, I am by no means a cmake expert, so if having a separate CMakeLists.txt file in the GISel directory is "better", I can add one there also.

[arsenm]

In D83100#2136392, @kbarton wrote:

In D83100#2134249, @tschuett wrote:

Pardon my cmake, but don't you need a CMakeLists.txt in the GISel sub-directory?

I thought I would too, but I added GISel/ prefix to the CMake in the PowerPC directory, which works.
This is the way it was done in the Aarch64 patch that did the refactoring.

That said, I am by no means a cmake expert, so if having a separate CMakeLists.txt file in the GISel directory is "better", I can add one there also.

It's not a separate library, so it's not better. Things are not layered to make this possible

[kbarton]

Fix warnings from clang-tidy and clang-format and rebase to latest version of master.

[arsenm]

llvm/lib/Target/PowerPC/PPCSubtarget.h

171

InlineAsmLowering is another boilerplate field, but you can also leave that for later

[kbarton]

• Add const to all parameters of createPPCInstructionSelector.
• Address review comments - minor clean in PPC::lowerFormalArguments and update comments.
• Put all new GlobalISel related files into new GISel subdirectory.
• Fix warnings from clang-tidy and clang-format.
• Remove unnecessary whitespace.

[arsenm]

llvm/test/CodeGen/PowerPC/GlobalISel/legalize-ret.mir

2

Don't need -global-isel if directly running MIR passes

llvm/lib/Target/PowerPC/CMakeLists.txt

 set(LLVM_TARGET_DEFINITIONS PPC.td)
 
 tablegen(LLVM PPCGenAsmMatcher.inc -gen-asm-matcher)
 tablegen(LLVM PPCGenAsmWriter.inc -gen-asm-writer)
 tablegen(LLVM PPCGenCallingConv.inc -gen-callingconv)
 tablegen(LLVM PPCGenDAGISel.inc -gen-dag-isel)
 tablegen(LLVM PPCGenDisassemblerTables.inc -gen-disassembler)
 tablegen(LLVM PPCGenFastISel.inc -gen-fast-isel)
 tablegen(LLVM PPCGenInstrInfo.inc -gen-instr-info)
 tablegen(LLVM PPCGenMCCodeEmitter.inc -gen-emitter)
 tablegen(LLVM PPCGenRegisterInfo.inc -gen-register-info)
 tablegen(LLVM PPCGenSubtargetInfo.inc -gen-subtarget)
 tablegen(LLVM PPCGenExegesis.inc -gen-exegesis)
+tablegen(LLVM PPCGenRegisterBank.inc -gen-register-bank)
+tablegen(LLVM PPCGenGlobalISel.inc -gen-global-isel)
 
 add_public_tablegen_target(PowerPCCommonTableGen)
 
 add_llvm_target(PowerPCCodeGen
+  GISel/PPCInstructionSelector.cpp
   PPCBoolRetToInt.cpp
   PPCAsmPrinter.cpp
   PPCBranchSelector.cpp
   PPCBranchCoalescing.cpp
   PPCCallingConv.cpp
   PPCCCState.cpp
   PPCCTRLoops.cpp
   PPCHazardRecognizers.cpp
add_llvm_target(PowerPCCodeGen
   PPCTLSDynamicCall.cpp
   PPCVSXCopy.cpp
   PPCReduceCRLogicals.cpp
   PPCVSXFMAMutate.cpp
   PPCVSXSwapRemoval.cpp
   PPCExpandISEL.cpp
   PPCPreEmitPeephole.cpp
   PPCLowerMASSVEntries.cpp
+  GISel/PPCCallLowering.cpp
+  GISel/PPCRegisterBankInfo.cpp
+  GISel/PPCLegalizerInfo.cpp
   )
 
 add_subdirectory(AsmParser)
 add_subdirectory(Disassembler)
 add_subdirectory(MCTargetDesc)
 add_subdirectory(TargetInfo)

llvm/lib/Target/PowerPC/GISel/PPCCallLowering.h

+//===-- PPCCallLowering.h - Call lowering for GlobalISel -------*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file describes how to lower LLVM calls to machine code calls.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_POWERPC_PPCCALLLOWERING_H
+#define LLVM_LIB_TARGET_POWERPC_PPCCALLLOWERING_H
+
+#include "PPCISelLowering.h"
+#include "llvm/CodeGen/GlobalISel/CallLowering.h"
+#include "llvm/IR/CallingConv.h"
+
+namespace llvm {
+
+class PPCTargetLowering;
+
+class PPCCallLowering : public CallLowering {
+public:
+  PPCCallLowering(const PPCTargetLowering &TLI);
+
+  bool lowerReturn(MachineIRBuilder &MIRBuilder, const Value *Val,
+                   ArrayRef<Register> VRegs,
+                   Register SwiftErrorVReg) const override;
+  bool lowerFormalArguments(MachineIRBuilder &MIRBuilder, const Function &F,
+                            ArrayRef<ArrayRef<Register>> VRegs) const override;
+  bool lowerCall(MachineIRBuilder &MIRBuilder,
+                 CallLoweringInfo &Info) const override;
+};
+} // end namespace llvm
+
+#endif

llvm/lib/Target/PowerPC/GISel/PPCCallLowering.cpp

+//===-- PPCCallLowering.h - Call lowering for GlobalISel -------*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file implements the lowering of LLVM calls to machine code calls for
+/// GlobalISel.
+///
+//===----------------------------------------------------------------------===//
+
+#include "PPCCallLowering.h"
+#include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "ppc-call-lowering"
+
+using namespace llvm;
+
+PPCCallLowering::PPCCallLowering(const PPCTargetLowering &TLI)
+    : CallLowering(&TLI) {}
+
+bool PPCCallLowering::lowerReturn(MachineIRBuilder &MIRBuilder,
+                                  const Value *Val, ArrayRef<Register> VRegs,
+                                  Register SwiftErrorVReg) const {
+  assert(((Val && !VRegs.empty()) || (!Val && VRegs.empty())) &&
+         "Return value without a vreg");
+  if (VRegs.size() > 0)
+    return false;
+
+  MIRBuilder.buildInstr(PPC::BLR8);
+  return true;
+}
+
+bool PPCCallLowering::lowerFormalArguments(
+    MachineIRBuilder &MIRBuilder, const Function &F,
+    ArrayRef<ArrayRef<Register>> VRegs) const {
+
+  // If VRegs is empty, then there are no formal arguments to lower and thus can
+  // always return true. If there are formal arguments, we currently do not
+  // handle them and thus return false.
+  return VRegs.empty();
+}
+
+bool PPCCallLowering::lowerCall(MachineIRBuilder &MIRBuilder,
+                                CallLoweringInfo &Info) const {
+  return false;
+}

llvm/lib/Target/PowerPC/GISel/PPCInstructionSelector.cpp

+//===- PPCInstructionSelector.cpp --------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file implements the targeting of the InstructionSelector class for
+/// PowerPC.
+//===----------------------------------------------------------------------===//
+
+#include "PPCInstrInfo.h"
+#include "PPCRegisterBankInfo.h"
+#include "PPCSubtarget.h"
+#include "PPCTargetMachine.h"
+#include "llvm/CodeGen/GlobalISel/InstructionSelector.h"
+#include "llvm/CodeGen/GlobalISel/InstructionSelectorImpl.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/IR/IntrinsicsPowerPC.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "ppc-gisel"
+
+using namespace llvm;
+
+namespace {
+
+#define GET_GLOBALISEL_PREDICATE_BITSET
+#include "PPCGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATE_BITSET
+
+class PPCInstructionSelector : public InstructionSelector {
+public:
+  PPCInstructionSelector(const PPCTargetMachine &TM, const PPCSubtarget &STI,
+                         const PPCRegisterBankInfo &RBI);
+
+  bool select(MachineInstr &I) override;
+  static const char *getName() { return DEBUG_TYPE; }
+
+private:
+  /// tblgen generated 'select' implementation that is used as the initial
+  /// selector for the patterns that do not require complex C++.
+  bool selectImpl(MachineInstr &I, CodeGenCoverage &CoverageInfo) const;
+
+  const PPCInstrInfo &TII;
+  const PPCRegisterInfo &TRI;
+  const PPCRegisterBankInfo &RBI;
+
+#define GET_GLOBALISEL_PREDICATES_DECL
+#include "PPCGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATES_DECL
+
+#define GET_GLOBALISEL_TEMPORARIES_DECL
+#include "PPCGenGlobalISel.inc"
+#undef GET_GLOBALISEL_TEMPORARIES_DECL
+};
+
+} // end anonymous namespace
+
+#define GET_GLOBALISEL_IMPL
+#include "PPCGenGlobalISel.inc"
+#undef GET_GLOBALISEL_IMPL
+
+PPCInstructionSelector::PPCInstructionSelector(const PPCTargetMachine &TM,
+                                               const PPCSubtarget &STI,
+                                               const PPCRegisterBankInfo &RBI)
+    : InstructionSelector(), TII(*STI.getInstrInfo()),
+      TRI(*STI.getRegisterInfo()), RBI(RBI),
+#define GET_GLOBALISEL_PREDICATES_INIT
+#include "PPCGenGlobalISel.inc"
+#undef GET_GLOBALISEL_PREDICATES_INIT
+#define GET_GLOBALISEL_TEMPORARIES_INIT
+#include "PPCGenGlobalISel.inc"
+#undef GET_GLOBALISEL_TEMPORARIES_INIT
+{
+}
+
+bool PPCInstructionSelector::select(MachineInstr &I) {
+  if (selectImpl(I, *CoverageInfo))
+    return true;
+  return false;
+}
+
+namespace llvm {
+InstructionSelector *
+createPPCInstructionSelector(const PPCTargetMachine &TM,
+                             const PPCSubtarget &Subtarget,
+                             const PPCRegisterBankInfo &RBI) {
+  return new PPCInstructionSelector(TM, Subtarget, RBI);
+}
+} // end namespace llvm

llvm/lib/Target/PowerPC/GISel/PPCLegalizerInfo.h

+//===- PPCLegalizerInfo.h ----------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file declares the targeting of the Machinelegalizer class for PowerPC
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_POWERPC_PPCMACHINELEGALIZER_H
+#define LLVM_LIB_TARGET_POWERPC_PPCMACHINELEGALIZER_H
+
+#include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
+
+namespace llvm {
+
+class PPCSubtarget;
+
+/// This class provides the information for the PowerPC target legalizer for
+/// GlobalISel.
+class PPCLegalizerInfo : public LegalizerInfo {
+public:
+  PPCLegalizerInfo(const PPCSubtarget &ST);
+};
+} // namespace llvm
+#endif

llvm/lib/Target/PowerPC/GISel/PPCLegalizerInfo.cpp

+//===- PPCLegalizerInfo.h ----------------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file implements the targeting of the Machinelegalizer class for PowerPC
+//===----------------------------------------------------------------------===//
+
+#include "PPCLegalizerInfo.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "ppc-legalinfo"
+
+using namespace llvm;
+using namespace LegalizeActions;
+
+PPCLegalizerInfo::PPCLegalizerInfo(const PPCSubtarget &ST) { computeTables(); }

llvm/lib/Target/PowerPC/GISel/PPCRegisterBankInfo.h

+//===-- PPCRegisterBankInfo.h -----------------------------------*- 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// This file declares the targeting of the RegisterBankInfo class for PowerPC.
+///
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_TARGET_PPC_PPCREGISTERBANKINFO_H
+#define LLVM_LIB_TARGET_PPC_PPCREGISTERBANKINFO_H
+
+#include "llvm/CodeGen/GlobalISel/RegisterBank.h"
+#include "llvm/CodeGen/GlobalISel/RegisterBankInfo.h"
+#include "llvm/CodeGen/TargetRegisterInfo.h"
+
+#define GET_REGBANK_DECLARATIONS
+#include "PPCGenRegisterBank.inc"
+
+namespace llvm {
+class TargetRegisterInfo;
+
+class PPCGenRegisterBankInfo : public RegisterBankInfo {
+protected:
+#define GET_TARGET_REGBANK_CLASS
+#include "PPCGenRegisterBank.inc"
+};
+
+class PPCRegisterBankInfo final : public PPCGenRegisterBankInfo {
+public:
+  PPCRegisterBankInfo(const TargetRegisterInfo &TRI);
+};
+} // namespace llvm
+
+#endif

llvm/lib/Target/PowerPC/GISel/PPCRegisterBankInfo.cpp

+//===- PPCRegisterBankInfo.cpp --------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+/// \file
+/// This file implements the targeting of the RegisterBankInfo class for
+/// PowerPC.
+//===----------------------------------------------------------------------===//
+
+#include "PPCRegisterBankInfo.h"
+#include "PPCRegisterInfo.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/Debug.h"
+
+#define DEBUG_TYPE "ppc-reg-bank-info"
+
+#define GET_TARGET_REGBANK_IMPL
+#include "PPCGenRegisterBank.inc"
+
+using namespace llvm;
+
+PPCRegisterBankInfo::PPCRegisterBankInfo(const TargetRegisterInfo &TRI)
+    : PPCGenRegisterBankInfo() {}

llvm/lib/Target/PowerPC/GISel/PPCRegisterBanks.td

+//===-- PPCRegisterBanks.td - Describe the PPC Banks -------*- tablegen -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// Define the PPC register banks used for GlobalISel.
+///
+//===----------------------------------------------------------------------===//
+
+/// General Purpose Registers
+def GPRRegBank : RegisterBank<"GPR", [G8RC]>;

llvm/lib/Target/PowerPC/LLVMBuild.txt

 has_asmprinter = 1
 has_disassembler = 1
 has_jit = 1
 
 [component_1]
 type = Library
 name = PowerPCCodeGen
 parent = PowerPC
-required_libraries = Analysis AsmPrinter CodeGen Core MC PowerPCDesc PowerPCInfo Scalar SelectionDAG Support Target TransformUtils
+required_libraries = Analysis AsmPrinter CodeGen Core MC PowerPCDesc PowerPCInfo Scalar SelectionDAG Support Target TransformUtils GlobalISel
 add_to_library_groups = PowerPC

llvm/lib/Target/PowerPC/PPC.h

 #define LLVM_LIB_TARGET_POWERPC_PPC_H
 
 #include "llvm/Support/CodeGen.h"
 
 // GCC #defines PPC on Linux but we use it as our namespace name
 #undef PPC
 
 namespace llvm {
-  class PPCTargetMachine;
-  class PassRegistry;
-  class FunctionPass;
-  class MachineInstr;
-  class MachineOperand;
-  class AsmPrinter;
-  class MCInst;
-  class MCOperand;
-  class ModulePass;
-  
-  FunctionPass *createPPCCTRLoops();
+class PPCRegisterBankInfo;
+class PPCSubtarget;
+class InstructionSelector;
 #ifndef NDEBUG
   FunctionPass *createPPCCTRLoopsVerify();
 #endif
   FunctionPass *createPPCLoopInstrFormPrepPass(PPCTargetMachine &TM);
   FunctionPass *createPPCTOCRegDepsPass();
   FunctionPass *createPPCEarlyReturnPass();
   FunctionPass *createPPCVSXCopyPass();
   FunctionPass *createPPCVSXFMAMutatePass();
#endif
   void initializePPCTLSDynamicCallPass(PassRegistry &);
   void initializePPCMIPeepholePass(PassRegistry&);
 
   extern char &PPCVSXFMAMutateID;
 
   ModulePass *createPPCLowerMASSVEntriesPass();
   void initializePPCLowerMASSVEntriesPass(PassRegistry &);
   extern char &PPCLowerMASSVEntriesID;
-  
+  InstructionSelector *
+  createPPCInstructionSelector(const PPCTargetMachine &, const PPCSubtarget &,
+                               const PPCRegisterBankInfo &);
   namespace PPCII {
 
   /// Target Operand Flag enum.
   enum TOF {
     //===------------------------------------------------------------------===//
     // PPC Specific MachineOperand flags.
     MO_NO_FLAG,
 

llvm/lib/Target/PowerPC/PPC.td

 }
 
 //===----------------------------------------------------------------------===//
 // Register File Description
 //===----------------------------------------------------------------------===//
 
 include "PPCRegisterInfo.td"
 include "PPCSchedule.td"
+include "GISel/PPCRegisterBanks.td"
 
 //===----------------------------------------------------------------------===//
 // PowerPC processors supported.
 //
 
 def : Processor<"generic", G3Itineraries, [Directive32, FeatureHardFloat,
                                            FeatureMFTB]>;
 def : ProcessorModel<"440", PPC440Model, [Directive440, FeatureISEL,

llvm/lib/Target/PowerPC/PPCSubtarget.h

 
 #ifndef LLVM_LIB_TARGET_POWERPC_PPCSUBTARGET_H
 #define LLVM_LIB_TARGET_POWERPC_PPCSUBTARGET_H
 
 #include "PPCFrameLowering.h"
 #include "PPCISelLowering.h"
 #include "PPCInstrInfo.h"
 #include "llvm/ADT/Triple.h"
+#include "llvm/CodeGen/GlobalISel/CallLowering.h"
+#include "llvm/CodeGen/GlobalISel/LegalizerInfo.h"
+#include "llvm/CodeGen/GlobalISel/RegisterBankInfo.h"
 #include "llvm/CodeGen/SelectionDAGTargetInfo.h"
 #include "llvm/CodeGen/TargetSubtargetInfo.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/MC/MCInstrItineraries.h"
 #include <string>
 
 #define GET_SUBTARGETINFO_HEADER
 #include "PPCGenSubtargetInfo.inc"
protected:
   bool IsQPXStackUnaligned;
 
   const PPCTargetMachine &TM;
   PPCFrameLowering FrameLowering;
   PPCInstrInfo InstrInfo;
   PPCTargetLowering TLInfo;
   SelectionDAGTargetInfo TSInfo;
 
+  /// GlobalISel related APIs.
+  std::unique_ptr<CallLowering> CallLoweringInfo;
+  std::unique_ptr<LegalizerInfo> Legalizer;
+  std::unique_ptr<RegisterBankInfo> RegBankInfo;
+  std::unique_ptr<InstructionSelector> InstSelector;
+
 public:
   /// This constructor initializes the data members to match that
   /// of the specified triple.
   ///
   PPCSubtarget(const Triple &TT, const std::string &CPU, const std::string &FS,
                const PPCTargetMachine &TM);
 
   /// ParseSubtargetFeatures - Parses features string setting specified
MCRegister getStackPointerRegister() const {
     return IsPPC64 ? PPC::X1 : PPC::R1;
   }
 
   bool isXRaySupported() const override { return IsPPC64 && IsLittleEndian; }
 
   bool isPredictableSelectIsExpensive() const {
     return PredictableSelectIsExpensive;
   }
+
+  // GlobalISEL
+  const CallLowering *getCallLowering() const override;
+  const RegisterBankInfo *getRegBankInfo() const override;
+  const LegalizerInfo *getLegalizerInfo() const override;
+  InstructionSelector *getInstructionSelector() const override;
 };
 } // End llvm namespace
 
 #endif

llvm/lib/Target/PowerPC/PPCSubtarget.cpp

 //===-- PowerPCSubtarget.cpp - PPC Subtarget Information ------------------===//
 //
 // 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 the PPC specific subclass of TargetSubtargetInfo.
 //
 //===----------------------------------------------------------------------===//
 
 #include "PPCSubtarget.h"
 #include "PPC.h"
+#include "GISel/PPCCallLowering.h"
+#include "GISel/PPCLegalizerInfo.h"
+#include "GISel/PPCRegisterBankInfo.h"
 #include "PPCRegisterInfo.h"
 #include "PPCTargetMachine.h"
+#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
 #include "llvm/CodeGen/MachineFunction.h"
 #include "llvm/CodeGen/MachineScheduler.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/GlobalValue.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetMachine.h"

 }
 
 PPCSubtarget::PPCSubtarget(const Triple &TT, const std::string &CPU,
                            const std::string &FS, const PPCTargetMachine &TM)
     : PPCGenSubtargetInfo(TT, CPU, FS), TargetTriple(TT),
       IsPPC64(TargetTriple.getArch() == Triple::ppc64 ||
               TargetTriple.getArch() == Triple::ppc64le),
       TM(TM), FrameLowering(initializeSubtargetDependencies(CPU, FS)),
-      InstrInfo(*this), TLInfo(TM, *this) {}
+      InstrInfo(*this), TLInfo(TM, *this) {
+  CallLoweringInfo.reset(new PPCCallLowering(*getTargetLowering()));
+  Legalizer.reset(new PPCLegalizerInfo(*this));
+  auto *RBI = new PPCRegisterBankInfo(*getRegisterInfo());
+  RegBankInfo.reset(RBI);
+
+  InstSelector.reset(createPPCInstructionSelector(
+      *static_cast<const PPCTargetMachine *>(&TM), *this, *RBI));
+}
 
 void PPCSubtarget::initializeEnvironment() {
   StackAlignment = Align(16);
   CPUDirective = PPC::DIR_NONE;
   HasMFOCRF = false;
   Has64BitSupport = false;
   Use64BitRegs = false;
   UseCRBits = false;

 
 bool PPCSubtarget::isELFv2ABI() const { return TM.isELFv2ABI(); }
 bool PPCSubtarget::isPPC64() const { return TM.isPPC64(); }
 
 bool PPCSubtarget::isUsingPCRelativeCalls() const {
   return isPPC64() && hasPCRelativeMemops() && isELFv2ABI() &&
          CodeModel::Medium == getTargetMachine().getCodeModel();
 }
+
+// GlobalISEL
+const CallLowering *PPCSubtarget::getCallLowering() const {
+  return CallLoweringInfo.get();
+}
+
+const RegisterBankInfo *PPCSubtarget::getRegBankInfo() const {
+  return RegBankInfo.get();
+}
+
+const LegalizerInfo *PPCSubtarget::getLegalizerInfo() const {
+  return Legalizer.get();
+}
+
+InstructionSelector *PPCSubtarget::getInstructionSelector() const {
+  return InstSelector.get();
+}

llvm/lib/Target/PowerPC/PPCTargetMachine.cpp

 #include "PPCTargetObjectFile.h"
 #include "PPCTargetTransformInfo.h"
 #include "TargetInfo/PowerPCTargetInfo.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/CodeGen/GlobalISel/IRTranslator.h"
+#include "llvm/CodeGen/GlobalISel/InstructionSelect.h"
+#include "llvm/CodeGen/GlobalISel/Legalizer.h"
+#include "llvm/CodeGen/GlobalISel/Localizer.h"
+#include "llvm/CodeGen/GlobalISel/RegBankSelect.h"
+#include "llvm/CodeGen/MachineScheduler.h"
 #include "llvm/CodeGen/Passes.h"
 #include "llvm/CodeGen/TargetPassConfig.h"
-#include "llvm/CodeGen/MachineScheduler.h"
 #include "llvm/IR/Attributes.h"
 #include "llvm/IR/DataLayout.h"
 #include "llvm/IR/Function.h"
+#include "llvm/InitializePasses.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/CodeGen.h"
 #include "llvm/Support/CommandLine.h"
 #include "llvm/Support/TargetRegistry.h"
 #include "llvm/Target/TargetLoweringObjectFile.h"
 #include "llvm/Target/TargetOptions.h"
 #include "llvm/Transforms/Scalar.h"
 #include <cassert>
#endif
   initializePPCBranchCoalescingPass(PR);
   initializePPCQPXLoadSplatPass(PR);
   initializePPCBoolRetToIntPass(PR);
   initializePPCExpandISELPass(PR);
   initializePPCPreEmitPeepholePass(PR);
   initializePPCTLSDynamicCallPass(PR);
   initializePPCMIPeepholePass(PR);
   initializePPCLowerMASSVEntriesPass(PR);
+  initializeGlobalISel(PR);
 }
 
 /// Return the datalayout string of a subtarget.
 static std::string getDataLayoutString(const Triple &T) {
   bool is64Bit = T.getArch() == Triple::ppc64 || T.getArch() == Triple::ppc64le;
   std::string Ret;
 
   // Most PPC* platforms are big endian, PPC64LE is little endian.
public:
   void addIRPasses() override;
   bool addPreISel() override;
   bool addILPOpts() override;
   bool addInstSelector() override;
   void addMachineSSAOptimization() override;
   void addPreRegAlloc() override;
   void addPreSched2() override;
   void addPreEmitPass() override;
+  // GlobalISEL
+  bool addIRTranslator() override;
+  bool addLegalizeMachineIR() override;
+  bool addRegBankSelect() override;
+  bool addGlobalInstructionSelect() override;
+
   ScheduleDAGInstrs *
   createMachineScheduler(MachineSchedContext *C) const override {
     return createPPCMachineScheduler(C);
   }
   ScheduleDAGInstrs *
   createPostMachineScheduler(MachineSchedContext *C) const override {
     return createPPCPostMachineScheduler(C);
   }

 PPCPreRASchedRegistry("ppc-prera",
                       "Run PowerPC PreRA specific scheduler",
                       createPPCMachineScheduler);
 
 static MachineSchedRegistry
 PPCPostRASchedRegistry("ppc-postra",
                        "Run PowerPC PostRA specific scheduler",
                        createPPCPostMachineScheduler);
+
+// Global ISEL
+bool PPCPassConfig::addIRTranslator() {
+  addPass(new IRTranslator());
+  return false;
+}
+
+bool PPCPassConfig::addLegalizeMachineIR() {
+  addPass(new Legalizer());
+  return false;
+}
+
+bool PPCPassConfig::addRegBankSelect() {
+  addPass(new RegBankSelect());
+  return false;
+}
+
+bool PPCPassConfig::addGlobalInstructionSelect() {
+  addPass(new InstructionSelect());
+  return false;
+}

llvm/test/CodeGen/PowerPC/GlobalISel/irtranslator-ret.ll

+; RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -global-isel -verify-machineinstrs -stop-after=irtranslator < %s | FileCheck %s
+
+; CHECK: name: f
+; CHECK: BLR8
+define void @f() {
+  ret void
+}

llvm/test/CodeGen/PowerPC/GlobalISel/legalize-ret.mir

+# RUN: llc -mtriple=powerpc64le-unknown-linux-gnu -global-isel -run-pass=legalizer -verify-machineinstrs %s -o - | FileCheck %s
+
+---
+name:            test_simple
+body:             |
+  ; CHECK-LABEL: name: test_simple
+  ; CHECK: [[IN:%[0-9]+]]:_(s64) = COPY $x3
+  ; CHECK: $x3 = COPY [[IN]]
+  ; CHECK: BLR8 implicit $lr8, implicit $rm, implicit $x3
+  bb.1.entry:
+    liveins: $x3
+  
+    %0:_(s64) = COPY $x3
+    $x3 = COPY %0(s64)
+    BLR8 implicit $lr8, implicit $rm, implicit $x3
+
+...