Change XCoreAsmPrinter to lower MachineInstrs to MCInsts before emission.

This change adds XCoreMCInstLower to do the lowering to MCInst and
XCoreInstPrinter to print the MCInsts.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@170288 91177308-0d34-0410-b5e6-96231b3b80d8

14 files changed, 401 insertions, 27 deletions

diff --git a/lib/Target/XCore/CMakeLists.txt b/lib/Target/XCore/CMakeLists.txt
index ca94f03..8742857 100644
--- a/lib/Target/XCore/CMakeLists.txt
+++ b/lib/Target/XCore/CMakeLists.txt
@@ -15,6 +15,7 @@ add_llvm_target(XCoreCodeGen
   XCoreISelDAGToDAG.cpp
   XCoreISelLowering.cpp
   XCoreMachineFunctionInfo.cpp
+  XCoreMCInstLower.cpp
   XCoreRegisterInfo.cpp
   XCoreSubtarget.cpp
   XCoreTargetMachine.cpp
@@ -24,5 +25,6 @@ add_llvm_target(XCoreCodeGen
 
 add_dependencies(LLVMXCoreCodeGen intrinsics_gen)
 
+add_subdirectory(InstPrinter)
 add_subdirectory(TargetInfo)
 add_subdirectory(MCTargetDesc)
diff --git a/lib/Target/XCore/InstPrinter/CMakeLists.txt b/lib/Target/XCore/InstPrinter/CMakeLists.txt
new file mode 100644
index 0000000..930e733
--- /dev/null
+++ b/lib/Target/XCore/InstPrinter/CMakeLists.txt
@@ -0,0 +1,7 @@
+include_directories( ${CMAKE_CURRENT_BINARY_DIR}/.. ${CMAKE_CURRENT_SOURCE_DIR}/.. )
+
+add_llvm_library(LLVMXCoreAsmPrinter
+  XCoreInstPrinter.cpp
+  )
+
+add_dependencies(LLVMXCoreAsmPrinter XCoreCommonTableGen)
diff --git a/lib/Target/XCore/InstPrinter/LLVMBuild.txt b/lib/Target/XCore/InstPrinter/LLVMBuild.txt
new file mode 100644
index 0000000..8750bc7
--- /dev/null
+++ b/lib/Target/XCore/InstPrinter/LLVMBuild.txt
@@ -0,0 +1,23 @@
+;===- ./lib/Target/XCore/InstPrinter/LLVMBuild.txt -------------*- Conf -*--===;
+;
+;                     The LLVM Compiler Infrastructure
+;
+; This file is distributed under the University of Illinois Open Source
+; License. See LICENSE.TXT for details.
+;
+;===------------------------------------------------------------------------===;
+;
+; This is an LLVMBuild description file for the components in this subdirectory.
+;
+; For more information on the LLVMBuild system, please see:
+;
+;   http://llvm.org/docs/LLVMBuild.html
+;
+;===------------------------------------------------------------------------===;
+
+[component_0]
+type = Library
+name = XCoreAsmPrinter
+parent = XCore
+required_libraries = MC Support
+add_to_library_groups = XCore
diff --git a/lib/Target/XCore/InstPrinter/Makefile b/lib/Target/XCore/InstPrinter/Makefile
new file mode 100644
index 0000000..1c1c612
--- /dev/null
+++ b/lib/Target/XCore/InstPrinter/Makefile
@@ -0,0 +1,16 @@
+##===- lib/Target/XCore/AsmPrinter/Makefile ----------------*- Makefile -*-===##
+#
+#                     The LLVM Compiler Infrastructure
+#
+# This file is distributed under the University of Illinois Open Source
+# License. See LICENSE.TXT for details.
+#
+##===----------------------------------------------------------------------===##
+
+LEVEL = ../../../..
+LIBRARYNAME = LLVMXCoreAsmPrinter
+
+# Hack: we need to include 'main' xcore target directory to grab private headers
+CPP.Flags += -I$(PROJ_OBJ_DIR)/.. -I$(PROJ_SRC_DIR)/..
+
+include $(LEVEL)/Makefile.common
diff --git a/lib/Target/XCore/InstPrinter/XCoreInstPrinter.cpp b/lib/Target/XCore/InstPrinter/XCoreInstPrinter.cpp
new file mode 100644
index 0000000..0ecbf63
--- /dev/null
+++ b/lib/Target/XCore/InstPrinter/XCoreInstPrinter.cpp
@@ -0,0 +1,96 @@
+//===-- XCoreInstPrinter.cpp - Convert XCore MCInst to assembly syntax ----===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class prints an XCore MCInst to a .s file.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "asm-printer"
+#include "XCoreInstPrinter.h"
+#include "llvm/ADT/StringExtras.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCSymbol.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+using namespace llvm;
+
+#include "XCoreGenAsmWriter.inc"
+
+void XCoreInstPrinter::printRegName(raw_ostream &OS, unsigned RegNo) const {
+  OS << StringRef(getRegisterName(RegNo)).lower();
+}
+
+void XCoreInstPrinter::printInst(const MCInst *MI, raw_ostream &O,
+                                 StringRef Annot) {
+  printInstruction(MI, O);
+  printAnnotation(O, Annot);
+}
+
+void XCoreInstPrinter::
+printInlineJT(const MCInst *MI, int opNum, raw_ostream &O) {
+  report_fatal_error("can't handle InlineJT");
+}
+
+void XCoreInstPrinter::
+printInlineJT32(const MCInst *MI, int opNum, raw_ostream &O) {
+  report_fatal_error("can't handle InlineJT32");
+}
+
+static void printExpr(const MCExpr *Expr, raw_ostream &OS) {
+  int Offset = 0;
+  const MCSymbolRefExpr *SRE;
+
+  if (const MCBinaryExpr *BE = dyn_cast<MCBinaryExpr>(Expr)) {
+    SRE = dyn_cast<MCSymbolRefExpr>(BE->getLHS());
+    const MCConstantExpr *CE = dyn_cast<MCConstantExpr>(BE->getRHS());
+    assert(SRE && CE && "Binary expression must be sym+const.");
+    Offset = CE->getValue();
+  } else if (!(SRE = dyn_cast<MCSymbolRefExpr>(Expr))) {
+    assert(false && "Unexpected MCExpr type.");
+  }
+  assert(SRE->getKind() == MCSymbolRefExpr::VK_None);
+
+  OS << SRE->getSymbol();
+
+  if (Offset) {
+    if (Offset > 0)
+      OS << '+';
+    OS << Offset;
+  }
+}
+
+void XCoreInstPrinter::
+printOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O) {
+  const MCOperand &Op = MI->getOperand(OpNo);
+  if (Op.isReg()) {
+    printRegName(O, Op.getReg());
+    return;
+  }
+
+  if (Op.isImm()) {
+    O << Op.getImm();
+    return;
+  }
+
+  assert(Op.isExpr() && "unknown operand kind in printOperand");
+  printExpr(Op.getExpr(), O);
+}
+
+void XCoreInstPrinter::
+printMemOperand(const MCInst *MI, int opNum, raw_ostream &O) {
+  printOperand(MI, opNum, O);
+
+  if (MI->getOperand(opNum+1).isImm() && MI->getOperand(opNum+1).getImm() == 0)
+    return;
+
+  O << "+";
+  printOperand(MI, opNum+1, O);
+}
diff --git a/lib/Target/XCore/InstPrinter/XCoreInstPrinter.h b/lib/Target/XCore/InstPrinter/XCoreInstPrinter.h
new file mode 100644
index 0000000..c394560
--- /dev/null
+++ b/lib/Target/XCore/InstPrinter/XCoreInstPrinter.h
@@ -0,0 +1,42 @@
+//== XCoreInstPrinter.h - Convert XCore MCInst to assembly syntax -*- C++ -*-=//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This class prints a XCore MCInst to a .s file.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef XCOREINSTPRINTER_H
+#define XCOREINSTPRINTER_H
+#include "llvm/MC/MCInstPrinter.h"
+
+namespace llvm {
+
+class TargetMachine;
+
+class XCoreInstPrinter : public MCInstPrinter {
+public:
+  XCoreInstPrinter(const MCAsmInfo &MAI, const MCInstrInfo &MII,
+                  const MCRegisterInfo &MRI)
+    : MCInstPrinter(MAI, MII, MRI) {}
+
+  // Autogenerated by tblgen.
+  void printInstruction(const MCInst *MI, raw_ostream &O);
+  static const char *getRegisterName(unsigned RegNo);
+
+  virtual void printRegName(raw_ostream &OS, unsigned RegNo) const;
+  virtual void printInst(const MCInst *MI, raw_ostream &O, StringRef Annot);
+private:
+  void printInlineJT(const MCInst *MI, int opNum, raw_ostream &O);
+  void printInlineJT32(const MCInst *MI, int opNum, raw_ostream &O);
+  void printOperand(const MCInst *MI, unsigned OpNo, raw_ostream &O);
+  void printMemOperand(const MCInst *MI, int opNum, raw_ostream &O);
+};
+} // end namespace llvm
+
+#endif
diff --git a/lib/Target/XCore/LLVMBuild.txt b/lib/Target/XCore/LLVMBuild.txt
index 53b4a9e..8c19dae 100644
--- a/lib/Target/XCore/LLVMBuild.txt
+++ b/lib/Target/XCore/LLVMBuild.txt
@@ -16,7 +16,7 @@
 ;===------------------------------------------------------------------------===;
 
 [common]
-subdirectories = MCTargetDesc TargetInfo
+subdirectories = InstPrinter MCTargetDesc TargetInfo
 
 [component_0]
 type = TargetGroup
diff --git a/lib/Target/XCore/MCTargetDesc/LLVMBuild.txt b/lib/Target/XCore/MCTargetDesc/LLVMBuild.txt
index a80c939..8213f9e 100644
--- a/lib/Target/XCore/MCTargetDesc/LLVMBuild.txt
+++ b/lib/Target/XCore/MCTargetDesc/LLVMBuild.txt
@@ -19,5 +19,5 @@
 type = Library
 name = XCoreDesc
 parent = XCore
-required_libraries = MC XCoreInfo
+required_libraries = MC XCoreAsmPrinter XCoreInfo
 add_to_library_groups = XCore
diff --git a/lib/Target/XCore/MCTargetDesc/XCoreMCTargetDesc.cpp b/lib/Target/XCore/MCTargetDesc/XCoreMCTargetDesc.cpp
index bbfdd43..048f9eb 100644
--- a/lib/Target/XCore/MCTargetDesc/XCoreMCTargetDesc.cpp
+++ b/lib/Target/XCore/MCTargetDesc/XCoreMCTargetDesc.cpp
@@ -13,6 +13,7 @@
 
 #include "XCoreMCTargetDesc.h"
 #include "XCoreMCAsmInfo.h"
+#include "InstPrinter/XCoreInstPrinter.h"
 #include "llvm/MC/MCCodeGenInfo.h"
 #include "llvm/MC/MCInstrInfo.h"
 #include "llvm/MC/MCRegisterInfo.h"
@@ -69,6 +70,15 @@ static MCCodeGenInfo *createXCoreMCCodeGenInfo(StringRef TT, Reloc::Model RM,
   return X;
 }
 
+static MCInstPrinter *createXCoreMCInstPrinter(const Target &T,
+                                               unsigned SyntaxVariant,
+                                               const MCAsmInfo &MAI,
+                                               const MCInstrInfo &MII,
+                                               const MCRegisterInfo &MRI,
+                                               const MCSubtargetInfo &STI) {
+  return new XCoreInstPrinter(MAI, MII, MRI);
+}
+
 // Force static initialization.
 extern "C" void LLVMInitializeXCoreTargetMC() {
   // Register the MC asm info.
@@ -87,4 +97,8 @@ extern "C" void LLVMInitializeXCoreTargetMC() {
   // Register the MC subtarget info.
   TargetRegistry::RegisterMCSubtargetInfo(TheXCoreTarget,
                                           createXCoreMCSubtargetInfo);
+
+  // Register the MCInstPrinter
+  TargetRegistry::RegisterMCInstPrinter(TheXCoreTarget,
+                                        createXCoreMCInstPrinter);
 }
diff --git a/lib/Target/XCore/Makefile b/lib/Target/XCore/Makefile
index b823c4e..7d6f920 100644
--- a/lib/Target/XCore/Makefile
+++ b/lib/Target/XCore/Makefile
@@ -17,7 +17,7 @@ BUILT_SOURCES = XCoreGenRegisterInfo.inc XCoreGenInstrInfo.inc \
                 XCoreGenDAGISel.inc XCoreGenCallingConv.inc \
 		XCoreGenSubtargetInfo.inc
 
-DIRS = TargetInfo MCTargetDesc
+DIRS = InstPrinter TargetInfo MCTargetDesc
 
 include $(LEVEL)/Makefile.common
 
diff --git a/lib/Target/XCore/XCore.td b/lib/Target/XCore/XCore.td
index 04a1dd5..e9a6d88 100644
--- a/lib/Target/XCore/XCore.td
+++ b/lib/Target/XCore/XCore.td
@@ -41,7 +41,13 @@ def : Proc<"xs1b-generic", []>;
 // Declare the target which we are implementing
 //===----------------------------------------------------------------------===//
 
+def XCoreAsmWriter : AsmWriter {
+  string AsmWriterClassName  = "InstPrinter";
+  bit isMCAsmWriter = 1;
+}
+
 def XCore : Target {
   // Pull in Instruction Info:
   let InstructionSet = XCoreInstrInfo;
+  let AssemblyWriters = [XCoreAsmWriter];
 }
diff --git a/lib/Target/XCore/XCoreAsmPrinter.cpp b/lib/Target/XCore/XCoreAsmPrinter.cpp
index 6760641..474d3aa 100644
--- a/lib/Target/XCore/XCoreAsmPrinter.cpp
+++ b/lib/Target/XCore/XCoreAsmPrinter.cpp
@@ -15,6 +15,8 @@
 #define DEBUG_TYPE "asm-printer"
 #include "XCore.h"
 #include "XCoreInstrInfo.h"
+#include "XCoreMCInstLower.h"
+#include "InstPrinter/XCoreInstPrinter.h"
 #include "XCoreSubtarget.h"
 #include "XCoreTargetMachine.h"
 #include "llvm/ADT/SmallString.h"
@@ -30,6 +32,7 @@
 #include "llvm/DebugInfo.h"
 #include "llvm/DerivedTypes.h"
 #include "llvm/MC/MCAsmInfo.h"
+#include "llvm/MC/MCInst.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/Module.h"
@@ -52,16 +55,17 @@ static cl::opt<unsigned> MaxThreads("xcore-max-threads", cl::Optional,
 namespace {
   class XCoreAsmPrinter : public AsmPrinter {
     const XCoreSubtarget &Subtarget;
+    XCoreMCInstLower MCInstLowering;
     void PrintDebugValueComment(const MachineInstr *MI, raw_ostream &OS);
   public:
     explicit XCoreAsmPrinter(TargetMachine &TM, MCStreamer &Streamer)
-      : AsmPrinter(TM, Streamer), Subtarget(TM.getSubtarget<XCoreSubtarget>()){}
+      : AsmPrinter(TM, Streamer), Subtarget(TM.getSubtarget<XCoreSubtarget>()),
+        MCInstLowering(*this) {}
 
     virtual const char *getPassName() const {
       return "XCore Assembly Printer";
     }
 
-    void printMemOperand(const MachineInstr *MI, int opNum, raw_ostream &O);
     void printInlineJT(const MachineInstr *MI, int opNum, raw_ostream &O,
                        const std::string &directive = ".jmptable");
     void printInlineJT32(const MachineInstr *MI, int opNum, raw_ostream &O) {
@@ -75,18 +79,14 @@ namespace {
     void emitArrayBound(MCSymbol *Sym, const GlobalVariable *GV);
     virtual void EmitGlobalVariable(const GlobalVariable *GV);
 
-    void printInstruction(const MachineInstr *MI, raw_ostream &O); // autogen'd.
-    static const char *getRegisterName(unsigned RegNo);
-
     void EmitFunctionEntryLabel();
     void EmitInstruction(const MachineInstr *MI);
+    void EmitFunctionBodyStart();
     void EmitFunctionBodyEnd();
     virtual MachineLocation getDebugValueLocation(const MachineInstr *MI) const;
   };
 } // end of anonymous namespace
 
-#include "XCoreGenAsmWriter.inc"
-
 void XCoreAsmPrinter::emitArrayBound(MCSymbol *Sym, const GlobalVariable *GV) {
   assert(((GV->hasExternalLinkage() ||
     GV->hasWeakLinkage()) ||
@@ -177,6 +177,10 @@ void XCoreAsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
   OutStreamer.EmitRawText("\t.cc_bottom " + Twine(GVSym->getName()) + ".data");
 }
 
+void XCoreAsmPrinter::EmitFunctionBodyStart() {
+  MCInstLowering.Initialize(Mang, &MF->getContext());
+}
+
 /// EmitFunctionBodyEnd - Targets can override this to emit stuff after
 /// the last basic block in the function.
 void XCoreAsmPrinter::EmitFunctionBodyEnd() {
@@ -192,17 +196,6 @@ void XCoreAsmPrinter::EmitFunctionEntryLabel() {
   OutStreamer.EmitLabel(CurrentFnSym);
 }
 
-void XCoreAsmPrinter::printMemOperand(const MachineInstr *MI, int opNum,
-                                      raw_ostream &O) {
-  printOperand(MI, opNum, O);
-  
-  if (MI->getOperand(opNum+1).isImm() && MI->getOperand(opNum+1).getImm() == 0)
-    return;
-  
-  O << "+";
-  printOperand(MI, opNum+1, O);
-}
-
 void XCoreAsmPrinter::
 printInlineJT(const MachineInstr *MI, int opNum, raw_ostream &O,
               const std::string &directive) {
@@ -225,7 +218,7 @@ void XCoreAsmPrinter::printOperand(const MachineInstr *MI, int opNum,
   const MachineOperand &MO = MI->getOperand(opNum);
   switch (MO.getType()) {
   case MachineOperand::MO_Register:
-    O << getRegisterName(MO.getReg());
+    O << XCoreInstPrinter::getRegisterName(MO.getReg());
     break;
   case MachineOperand::MO_Immediate:
     O << MO.getImm();
@@ -270,7 +263,7 @@ bool XCoreAsmPrinter::PrintAsmOperand(const MachineInstr *MI, unsigned OpNo,
       return AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, O);
     }
 
-printOperand(MI, OpNo, O);
+  printOperand(MI, OpNo, O);
   return false;
 }
 
@@ -317,15 +310,30 @@ void XCoreAsmPrinter::EmitInstruction(const MachineInstr *MI) {
   }
   case XCore::ADD_2rus:
     if (MI->getOperand(2).getImm() == 0) {
-      O << "\tmov " << getRegisterName(MI->getOperand(0).getReg()) << ", "
-        << getRegisterName(MI->getOperand(1).getReg());
+      O << "\tmov "
+        << XCoreInstPrinter::getRegisterName(MI->getOperand(0).getReg()) << ", "
+        << XCoreInstPrinter::getRegisterName(MI->getOperand(1).getReg());
       OutStreamer.EmitRawText(O.str());
       return;
     }
     break;
+  case XCore::BR_JT:
+  case XCore::BR_JT32:
+    O << "\tbru "
+      << XCoreInstPrinter::getRegisterName(MI->getOperand(1).getReg()) << '\n';
+    if (MI->getOpcode() == XCore::BR_JT)
+      printInlineJT(MI, 0, O);
+    else
+      printInlineJT32(MI, 0, O);
+    O << '\n';
+    OutStreamer.EmitRawText(O.str());
+    return;
   }
-  printInstruction(MI, O);
-  OutStreamer.EmitRawText(O.str());
+
+  MCInst TmpInst;
+  MCInstLowering.Lower(MI, TmpInst);
+
+  OutStreamer.EmitInstruction(TmpInst);
 }
 
 // Force static initialization.
diff --git a/lib/Target/XCore/XCoreMCInstLower.cpp b/lib/Target/XCore/XCoreMCInstLower.cpp
new file mode 100644
index 0000000..7cdbada
--- /dev/null
+++ b/lib/Target/XCore/XCoreMCInstLower.cpp
@@ -0,0 +1,116 @@
+//===-- XCoreMCInstLower.cpp - Convert XCore MachineInstr to MCInst -------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains code to lower XCore MachineInstrs to their corresponding
+// MCInst records.
+//
+//===----------------------------------------------------------------------===//
+#include "XCoreMCInstLower.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/MC/MCContext.h"
+#include "llvm/MC/MCExpr.h"
+#include "llvm/MC/MCInst.h"
+#include "llvm/Target/Mangler.h"
+
+using namespace llvm;
+
+XCoreMCInstLower::XCoreMCInstLower(class AsmPrinter &asmprinter)
+: Printer(asmprinter) {}
+
+void XCoreMCInstLower::Initialize(Mangler *M, MCContext *C) {
+  Mang = M;
+  Ctx = C;
+}
+
+MCOperand XCoreMCInstLower::LowerSymbolOperand(const MachineOperand &MO,
+                                               MachineOperandType MOTy,
+                                               unsigned Offset) const {
+  MCSymbolRefExpr::VariantKind Kind = MCSymbolRefExpr::VK_None;
+  const MCSymbol *Symbol;
+
+  switch (MOTy) {
+    case MachineOperand::MO_MachineBasicBlock:
+      Symbol = MO.getMBB()->getSymbol();
+      break;
+    case MachineOperand::MO_GlobalAddress:
+      Symbol = Mang->getSymbol(MO.getGlobal());
+      Offset += MO.getOffset();
+      break;
+    case MachineOperand::MO_BlockAddress:
+      Symbol = Printer.GetBlockAddressSymbol(MO.getBlockAddress());
+      Offset += MO.getOffset();
+      break;
+    case MachineOperand::MO_ExternalSymbol:
+      Symbol = Printer.GetExternalSymbolSymbol(MO.getSymbolName());
+      Offset += MO.getOffset();
+      break;
+    case MachineOperand::MO_JumpTableIndex:
+      Symbol = Printer.GetJTISymbol(MO.getIndex());
+      break;
+    case MachineOperand::MO_ConstantPoolIndex:
+      Symbol = Printer.GetCPISymbol(MO.getIndex());
+      Offset += MO.getOffset();
+      break;
+    default:
+      llvm_unreachable("<unknown operand type>");
+  }
+
+  const MCSymbolRefExpr *MCSym = MCSymbolRefExpr::Create(Symbol, Kind, *Ctx);
+
+  if (!Offset)
+    return MCOperand::CreateExpr(MCSym);
+
+  // Assume offset is never negative.
+  assert(Offset > 0);
+
+  const MCConstantExpr *OffsetExpr =  MCConstantExpr::Create(Offset, *Ctx);
+  const MCBinaryExpr *Add = MCBinaryExpr::CreateAdd(MCSym, OffsetExpr, *Ctx);
+  return MCOperand::CreateExpr(Add);
+}
+
+MCOperand XCoreMCInstLower::LowerOperand(const MachineOperand &MO,
+                                         unsigned offset) const {
+  MachineOperandType MOTy = MO.getType();
+
+  switch (MOTy) {
+    default: llvm_unreachable("unknown operand type");
+    case MachineOperand::MO_Register:
+      // Ignore all implicit register operands.
+      if (MO.isImplicit()) break;
+      return MCOperand::CreateReg(MO.getReg());
+    case MachineOperand::MO_Immediate:
+      return MCOperand::CreateImm(MO.getImm() + offset);
+    case MachineOperand::MO_MachineBasicBlock:
+    case MachineOperand::MO_GlobalAddress:
+    case MachineOperand::MO_ExternalSymbol:
+    case MachineOperand::MO_JumpTableIndex:
+    case MachineOperand::MO_ConstantPoolIndex:
+    case MachineOperand::MO_BlockAddress:
+      return LowerSymbolOperand(MO, MOTy, offset);
+    case MachineOperand::MO_RegisterMask:
+      break;
+  }
+
+  return MCOperand();
+}
+
+void XCoreMCInstLower::Lower(const MachineInstr *MI, MCInst &OutMI) const {
+  OutMI.setOpcode(MI->getOpcode());
+
+  for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+    const MachineOperand &MO = MI->getOperand(i);
+    MCOperand MCOp = LowerOperand(MO);
+
+    if (MCOp.isValid())
+      OutMI.addOperand(MCOp);
+  }
+}
diff --git a/lib/Target/XCore/XCoreMCInstLower.h b/lib/Target/XCore/XCoreMCInstLower.h
new file mode 100644
index 0000000..10bf5d8
--- /dev/null
+++ b/lib/Target/XCore/XCoreMCInstLower.h
@@ -0,0 +1,44 @@
+//===-- XCoreMCInstLower.h - Lower MachineInstr to MCInst ------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef XCOREMCINSTLOWER_H
+#define XCOREMCINSTLOWER_H
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/CodeGen/MachineOperand.h"
+#include "llvm/Support/Compiler.h"
+
+namespace llvm {
+  class MCContext;
+  class MCInst;
+  class MCOperand;
+  class MachineInstr;
+  class MachineFunction;
+  class Mangler;
+  class AsmPrinter;
+
+/// XCoreMCInstLower - This class is used to lower an MachineInstr into an
+//                     MCInst.
+class LLVM_LIBRARY_VISIBILITY XCoreMCInstLower {
+  typedef MachineOperand::MachineOperandType MachineOperandType;
+  MCContext *Ctx;
+  Mangler *Mang;
+  AsmPrinter &Printer;
+public:
+  XCoreMCInstLower(class AsmPrinter &asmprinter);
+  void Initialize(Mangler *mang, MCContext *C);
+  void Lower(const MachineInstr *MI, MCInst &OutMI) const;
+  MCOperand LowerOperand(const MachineOperand& MO, unsigned offset = 0) const;
+
+private:
+  MCOperand LowerSymbolOperand(const MachineOperand &MO,
+                               MachineOperandType MOTy, unsigned Offset) const;
+};
+}
+
+#endif