Addition of the PPC32 Pattern ISel. While it is far from complete, it will

be brought up to parity with the current simple ISel in the coming days.
Currently, -pattern-isel is required to trigger it.

llvm-svn: 20805

3 files changed, 761 insertions, 0 deletions

diff --git a/llvm/lib/Target/PowerPC/PPC32ISelPattern.cpp b/llvm/lib/Target/PowerPC/PPC32ISelPattern.cpp
new file mode 100644
index 00000000000..5ea31ef6187
--- /dev/null
+++ b/llvm/lib/Target/PowerPC/PPC32ISelPattern.cpp
@@ -0,0 +1,756 @@
+//===-- PPC32ISelPattern.cpp - A pattern matching inst selector for PPC32 -===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and is distributed under
+// the University of Illinois Open Source License. See LICENSE.TXT for details.
+// 
+//===----------------------------------------------------------------------===//
+//
+// This file defines a pattern matching instruction selector for 32 bit PowerPC.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PowerPC.h"
+#include "PowerPCInstrBuilder.h"
+#include "PowerPCInstrInfo.h"
+#include "PPC32RegisterInfo.h"
+#include "llvm/Constants.h"                   // FIXME: REMOVE
+#include "llvm/Function.h"
+#include "llvm/CodeGen/MachineConstantPool.h" // FIXME: REMOVE
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/SelectionDAG.h"
+#include "llvm/CodeGen/SelectionDAGISel.h"
+#include "llvm/CodeGen/SSARegMap.h"
+#include "llvm/Target/TargetData.h"
+#include "llvm/Target/TargetLowering.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/MathExtras.h"
+#include "llvm/ADT/Statistic.h"
+#include <set>
+#include <algorithm>
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//  PPC32TargetLowering - PPC32 Implementation of the TargetLowering interface
+namespace {
+  class PPC32TargetLowering : public TargetLowering {
+    int VarArgsFrameIndex;            // FrameIndex for start of varargs area.
+    int ReturnAddrIndex;              // FrameIndex for return slot.
+  public:
+    PPC32TargetLowering(TargetMachine &TM) : TargetLowering(TM) {
+      // Set up the TargetLowering object.
+
+      // Set up the register classes.
+      addRegisterClass(MVT::i32, PPC32::GPRCRegisterClass);
+      addRegisterClass(MVT::f32, PPC32::GPRCRegisterClass);
+      addRegisterClass(MVT::f64, PPC32::FPRCRegisterClass);
+      
+      computeRegisterProperties();
+    }
+
+    /// LowerArguments - This hook must be implemented to indicate how we should
+    /// lower the arguments for the specified function, into the specified DAG.
+    virtual std::vector<SDOperand>
+    LowerArguments(Function &F, SelectionDAG &DAG);
+    
+    /// LowerCallTo - This hook lowers an abstract call to a function into an
+    /// actual call.
+    virtual std::pair<SDOperand, SDOperand>
+    LowerCallTo(SDOperand Chain, const Type *RetTy, SDOperand Callee,
+                ArgListTy &Args, SelectionDAG &DAG);
+    
+    virtual std::pair<SDOperand, SDOperand>
+    LowerVAStart(SDOperand Chain, SelectionDAG &DAG);
+    
+    virtual std::pair<SDOperand,SDOperand>
+    LowerVAArgNext(bool isVANext, SDOperand Chain, SDOperand VAList,
+                   const Type *ArgTy, SelectionDAG &DAG);
+
+    virtual std::pair<SDOperand, SDOperand>
+    LowerFrameReturnAddress(bool isFrameAddr, SDOperand Chain, unsigned Depth,
+                            SelectionDAG &DAG);
+  };
+}
+
+
+std::vector<SDOperand>
+PPC32TargetLowering::LowerArguments(Function &F, SelectionDAG &DAG) {
+  //
+  // add beautiful description of PPC stack frame format, or at least some docs
+  //
+  MachineFunction &MF = DAG.getMachineFunction();
+  MachineFrameInfo *MFI = MF.getFrameInfo();
+  MachineBasicBlock& BB = MF.front();
+  std::vector<SDOperand> ArgValues;
+  
+  // Due to the rather complicated nature of the PowerPC ABI, rather than a 
+  // fixed size array of physical args, for the sake of simplicity let the STL
+  // handle tracking them for us.
+  std::vector<unsigned> argVR, argPR, argOp;
+  unsigned ArgOffset = 24;
+  unsigned GPR_remaining = 8;
+  unsigned FPR_remaining = 13;
+  unsigned GPR_idx = 0, FPR_idx = 0;
+  static const unsigned GPR[] = { 
+    PPC::R3, PPC::R4, PPC::R5, PPC::R6,
+    PPC::R7, PPC::R8, PPC::R9, PPC::R10,
+  };
+  static const unsigned FPR[] = {
+    PPC::F1, PPC::F2, PPC::F3, PPC::F4, PPC::F5, PPC::F6, PPC::F7,
+    PPC::F8, PPC::F9, PPC::F10, PPC::F11, PPC::F12, PPC::F13
+  };
+
+  // Add DAG nodes to load the arguments...  On entry to a function on PPC,
+  // the arguments start at offset 24, although they are likely to be passed
+  // in registers.
+  for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) {
+    SDOperand newroot, argt;
+    unsigned ObjSize;
+    bool needsLoad = false;
+    MVT::ValueType ObjectVT = getValueType(I->getType());
+    
+    switch (ObjectVT) {
+    default: assert(0 && "Unhandled argument type!");
+    case MVT::i1:
+    case MVT::i8:
+    case MVT::i16:
+    case MVT::i32: 
+      ObjSize = 4;
+      if (GPR_remaining > 0) {
+        BuildMI(&BB, PPC::IMPLICIT_DEF, 0, GPR[GPR_idx]);
+        unsigned virtReg = 
+          MF.getSSARegMap()->createVirtualRegister(getRegClassFor(MVT::i32));
+        argt = newroot = DAG.getCopyFromReg(virtReg, MVT::i32, DAG.getRoot());
+        if (ObjectVT != MVT::i32)
+          argt = DAG.getNode(ISD::TRUNCATE, ObjectVT, newroot);
+        argVR.push_back(virtReg);
+        argPR.push_back(GPR[GPR_idx]);
+        argOp.push_back(PPC::OR);
+      } else {
+        needsLoad = true;
+      }
+      break;
+      case MVT::i64: ObjSize = 8; 
+      if (GPR_remaining > 1) {
+        BuildMI(&BB, PPC::IMPLICIT_DEF, 0, GPR[GPR_idx]);
+        BuildMI(&BB, PPC::IMPLICIT_DEF, 0, GPR[GPR_idx+1]);
+        MF.getSSARegMap()->createVirtualRegister(getRegClassFor(MVT::i32));
+        unsigned virtReg = 
+          MF.getSSARegMap()->createVirtualRegister(getRegClassFor(MVT::i32))-1;
+        // FIXME: is this correct?
+        argt = newroot = DAG.getCopyFromReg(virtReg, MVT::i32, DAG.getRoot());
+        argt = DAG.getCopyFromReg(virtReg+1, MVT::i32, newroot);
+        // Push the arguments for emitting into BB later
+        argVR.push_back(virtReg);       argVR.push_back(virtReg+1);
+        argPR.push_back(GPR[GPR_idx]);  argPR.push_back(GPR[GPR_idx+1]);
+        argOp.push_back(PPC::OR);       argOp.push_back(PPC::OR);
+      } else {
+        needsLoad = true; 
+      }
+      break;
+      case MVT::f32: ObjSize = 4;
+      case MVT::f64: ObjSize = 8;
+      if (FPR_remaining > 0) {
+        BuildMI(&BB, PPC::IMPLICIT_DEF, 0, FPR[FPR_idx]);
+        unsigned virtReg = 
+          MF.getSSARegMap()->createVirtualRegister(getRegClassFor(ObjectVT));
+        argt = newroot = DAG.getCopyFromReg(virtReg, ObjectVT, DAG.getRoot());
+        argVR.push_back(virtReg);
+        argPR.push_back(FPR[FPR_idx]);
+        argOp.push_back(PPC::FMR);
+        --FPR_remaining;
+        ++FPR_idx;
+      } else {
+        needsLoad = true;
+      }
+      break;
+    }
+    
+    // We need to load the argument to a virtual register if we determined above
+    // that we ran out of physical registers of the appropriate type 
+    if (needsLoad) {
+      int FI = MFI->CreateFixedObject(ObjSize, ArgOffset);
+      SDOperand FIN = DAG.getFrameIndex(FI, MVT::i32);
+      argt = newroot = DAG.getLoad(ObjectVT, DAG.getEntryNode(), FIN);
+    }
+    
+    // Every 4 bytes of argument space consumes one of the GPRs available for
+    // argument passing.
+    if (GPR_remaining > 0) {
+      unsigned delta = (GPR_remaining > 1 && ObjSize == 8) ? 2 : 1;
+      GPR_remaining -= delta;
+      GPR_idx += delta;
+    }
+    ArgOffset += ObjSize;
+    
+    DAG.setRoot(newroot.getValue(1));
+    ArgValues.push_back(argt);
+  }
+
+  for (int i = 0, count = argVR.size(); i < count; ++i) {
+    if (argOp[i] == PPC::FMR)
+      BuildMI(&BB, argOp[i], 1, argVR[i]).addReg(argPR[i]);
+    else
+      BuildMI(&BB, argOp[i], 2, argVR[i]).addReg(argPR[i]).addReg(argPR[i]);
+  }
+
+  // If the function takes variable number of arguments, make a frame index for
+  // the start of the first vararg value... for expansion of llvm.va_start.
+  if (F.isVarArg())
+    VarArgsFrameIndex = MFI->CreateFixedObject(4, ArgOffset);
+
+  return ArgValues;
+}
+
+std::pair<SDOperand, SDOperand>
+PPC32TargetLowering::LowerCallTo(SDOperand Chain,
+				 const Type *RetTy, SDOperand Callee,
+				 ArgListTy &Args, SelectionDAG &DAG) {
+  // FIXME
+  int NumBytes = 56;
+
+  Chain = DAG.getNode(ISD::ADJCALLSTACKDOWN, MVT::Other, Chain,
+		      DAG.getConstant(NumBytes, getPointerTy()));
+  std::vector<SDOperand> args_to_use;
+  for (unsigned i = 0, e = Args.size(); i != e; ++i)
+  {
+    switch (getValueType(Args[i].second)) {
+    default: assert(0 && "Unexpected ValueType for argument!");
+    case MVT::i1:
+    case MVT::i8:
+    case MVT::i16:
+    case MVT::i32:
+    case MVT::i64:
+    case MVT::f64:
+    case MVT::f32:
+      break;
+    }
+    args_to_use.push_back(Args[i].first);
+  }
+  
+  std::vector<MVT::ValueType> RetVals;
+  MVT::ValueType RetTyVT = getValueType(RetTy);
+  if (RetTyVT != MVT::isVoid)
+    RetVals.push_back(RetTyVT);
+  RetVals.push_back(MVT::Other);
+
+  SDOperand TheCall = SDOperand(DAG.getCall(RetVals, 
+                                            Chain, Callee, args_to_use), 0);
+  Chain = TheCall.getValue(RetTyVT != MVT::isVoid);
+  Chain = DAG.getNode(ISD::ADJCALLSTACKUP, MVT::Other, Chain,
+                      DAG.getConstant(NumBytes, getPointerTy()));
+  return std::make_pair(TheCall, Chain);
+}
+
+std::pair<SDOperand, SDOperand>
+PPC32TargetLowering::LowerVAStart(SDOperand Chain, SelectionDAG &DAG) {
+  //vastart just returns the address of the VarArgsFrameIndex slot.
+  return std::make_pair(DAG.getFrameIndex(VarArgsFrameIndex, MVT::i32), Chain);
+}
+
+std::pair<SDOperand,SDOperand> PPC32TargetLowering::
+LowerVAArgNext(bool isVANext, SDOperand Chain, SDOperand VAList,
+               const Type *ArgTy, SelectionDAG &DAG) {
+  abort();
+}
+               
+
+std::pair<SDOperand, SDOperand> PPC32TargetLowering::
+LowerFrameReturnAddress(bool isFrameAddress, SDOperand Chain, unsigned Depth,
+                        SelectionDAG &DAG) {
+  abort();
+}
+
+namespace {
+
+//===--------------------------------------------------------------------===//
+/// ISel - PPC32 specific code to select PPC32 machine instructions for
+/// SelectionDAG operations.
+//===--------------------------------------------------------------------===//
+class ISel : public SelectionDAGISel {
+  
+  /// Comment Here.
+  PPC32TargetLowering PPC32Lowering;
+  
+  /// ExprMap - As shared expressions are codegen'd, we keep track of which
+  /// vreg the value is produced in, so we only emit one copy of each compiled
+  /// tree.
+  std::map<SDOperand, unsigned> ExprMap;
+  
+public:
+  ISel(TargetMachine &TM) : SelectionDAGISel(PPC32Lowering), PPC32Lowering(TM) 
+  {}
+  
+  /// InstructionSelectBasicBlock - This callback is invoked by
+  /// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
+  virtual void InstructionSelectBasicBlock(SelectionDAG &DAG) {
+    DEBUG(BB->dump());
+    // Codegen the basic block.
+    Select(DAG.getRoot());
+    
+    // Clear state used for selection.
+    ExprMap.clear();
+  }
+  
+  unsigned SelectExpr(SDOperand N);
+  unsigned SelectExprFP(SDOperand N, unsigned Result);
+  void Select(SDOperand N);
+  
+  void SelectAddr(SDOperand N, unsigned& Reg, int& offset);
+  void SelectBranchCC(SDOperand N);
+};
+
+/// canUseAsImmediateForOpcode - This method returns a value indicating whether
+/// the ConstantSDNode N can be used as an immediate to Opcode.  The return
+/// values are either 0, 1 or 2.  0 indicates that either N is not a
+/// ConstantSDNode, or is not suitable for use by that opcode.  A return value 
+/// of 1 indicates that the constant may be used in normal immediate form.  A
+/// return value of 2 indicates that the constant may be used in shifted
+/// immediate form.  If the return value is nonzero, the constant value is
+/// placed in Imm.
+///
+static unsigned canUseAsImmediateForOpcode(SDOperand N, unsigned Opcode,
+                                           unsigned& Imm) {
+  if (N.getOpcode() != ISD::Constant) return 0;
+
+  int v = (int)cast<ConstantSDNode>(N)->getSignExtended();
+  
+  switch(Opcode) {
+  default: return 0;
+  case ISD::ADD:
+    if (v <= 32767 && v >= -32768) { Imm = v & 0xFFFF; return 1; }
+    if ((v & 0x0000FFFF) == 0) { Imm = v >> 16; return 2; }
+    break;
+  case ISD::AND:
+  case ISD::XOR:
+  case ISD::OR:
+    if (v >= 0 && v <= 65535) { Imm = v & 0xFFFF; return 1; }
+    if ((v & 0x0000FFFF) == 0) { Imm = v >> 16; return 2; }
+    break;
+  }
+  return 0;
+}
+}
+
+//Check to see if the load is a constant offset from a base register
+void ISel::SelectAddr(SDOperand N, unsigned& Reg, int& offset)
+{
+  Reg = SelectExpr(N);
+  offset = 0;
+  return;
+}
+
+void ISel::SelectBranchCC(SDOperand N)
+{
+  assert(N.getOpcode() == ISD::BRCOND && "Not a BranchCC???");
+  MachineBasicBlock *Dest = 
+    cast<BasicBlockSDNode>(N.getOperand(2))->getBasicBlock();
+  unsigned Opc;
+  
+  Select(N.getOperand(0));  //chain
+  SDOperand CC = N.getOperand(1);
+  
+  //Giveup and do the stupid thing
+  unsigned Tmp1 = SelectExpr(CC);
+  BuildMI(BB, PPC::BNE, 2).addReg(Tmp1).addMBB(Dest);
+  return;
+}
+
+unsigned ISel::SelectExprFP(SDOperand N, unsigned Result)
+{
+  unsigned Tmp1, Tmp2, Tmp3;
+  unsigned Opc = 0;
+  SDNode *Node = N.Val;
+  MVT::ValueType DestType = N.getValueType();
+  unsigned opcode = N.getOpcode();
+
+  switch (opcode) {
+  default:
+    Node->dump();
+    assert(0 && "Node not handled!\n");
+
+  case ISD::SELECT:
+    abort();
+    
+  case ISD::FP_ROUND:
+    assert (DestType == MVT::f32 && 
+            N.getOperand(0).getValueType() == MVT::f64 && 
+            "only f64 to f32 conversion supported here");
+    Tmp1 = SelectExpr(N.getOperand(0));
+    BuildMI(BB, PPC::FRSP, 1, Result).addReg(Tmp1);
+    return Result;
+
+  case ISD::FP_EXTEND:
+    assert (DestType == MVT::f64 && 
+            N.getOperand(0).getValueType() == MVT::f32 && 
+            "only f32 to f64 conversion supported here");
+    Tmp1 = SelectExpr(N.getOperand(0));
+    BuildMI(BB, PPC::FMR, 1, Result).addReg(Tmp1);
+    return Result;
+
+  case ISD::CopyFromReg:
+    // FIXME: Handle copy from physregs!
+    // Just use the specified register as our input.
+    return dyn_cast<RegSDNode>(Node)->getReg();
+    
+  case ISD::LOAD:
+    abort();
+    
+  case ISD::ConstantFP:
+    abort();
+    
+  case ISD::MUL:
+  case ISD::ADD:
+  case ISD::SUB:
+  case ISD::SDIV:
+    switch( opcode ) {
+    case ISD::MUL:  Opc = DestType == MVT::f64 ? PPC::FMUL : PPC::FMULS; break;
+    case ISD::ADD:  Opc = DestType == MVT::f64 ? PPC::FADD : PPC::FADDS; break;
+    case ISD::SUB:  Opc = DestType == MVT::f64 ? PPC::FSUB : PPC::FSUBS; break;
+    case ISD::SDIV: Opc = DestType == MVT::f64 ? PPC::FDIV : PPC::FDIVS; break;
+    };
+
+    Tmp1 = SelectExpr(N.getOperand(0));
+    Tmp2 = SelectExpr(N.getOperand(1));
+    BuildMI(BB, Opc, 2, Result).addReg(Tmp1).addReg(Tmp2);
+    return Result;
+
+  case ISD::EXTLOAD:
+    abort();
+
+  case ISD::UINT_TO_FP:
+  case ISD::SINT_TO_FP:
+    abort();
+  }
+  assert(0 && "should not get here");
+  return 0;
+}
+
+unsigned ISel::SelectExpr(SDOperand N) {
+  unsigned Result;
+  unsigned Tmp1, Tmp2, Tmp3;
+  unsigned Opc = 0;
+  unsigned opcode = N.getOpcode();
+
+  SDNode *Node = N.Val;
+  MVT::ValueType DestType = N.getValueType();
+
+  unsigned &Reg = ExprMap[N];
+  if (Reg) return Reg;
+
+  if (DestType == MVT::f64 || DestType == MVT::f32)
+    return SelectExprFP(N, Result);
+
+  if (N.getOpcode() != ISD::CALL)
+    Reg = Result = (N.getValueType() != MVT::Other) ?
+      MakeReg(N.getValueType()) : 1;
+  else
+    abort(); // FIXME: Implement Call
+
+  switch (opcode) {
+  default:
+    Node->dump();
+    assert(0 && "Node not handled!\n");
+ 
+  case ISD::DYNAMIC_STACKALLOC:
+    abort();
+
+  case ISD::ConstantPool:
+    abort();
+
+  case ISD::FrameIndex:
+    abort();
+  
+  case ISD::EXTLOAD:
+  case ISD::ZEXTLOAD:
+  case ISD::SEXTLOAD:
+  case ISD::LOAD:
+  case ISD::GlobalAddress:
+  case ISD::CALL:
+    abort();
+
+  case ISD::SIGN_EXTEND:
+  case ISD::SIGN_EXTEND_INREG:
+    Tmp1 = SelectExpr(N.getOperand(0));
+    BuildMI(BB, PPC::EXTSH, 1, Result).addReg(Tmp1);
+    return Result;
+    
+  case ISD::ZERO_EXTEND_INREG:
+    Tmp1 = SelectExpr(N.getOperand(0));
+    switch(cast<MVTSDNode>(Node)->getExtraValueType()) {
+    default:
+      Node->dump();
+      assert(0 && "Zero Extend InReg not there yet");
+      break;
+    case MVT::i16:  Tmp2 = 16; break;
+    case MVT::i8:   Tmp2 = 24; break;
+    case MVT::i1:   Tmp2 = 31; break;
+    }
+    BuildMI(BB, PPC::RLWINM, 5, Result).addReg(Tmp1).addImm(0).addImm(0)
+      .addImm(Tmp2).addImm(31);
+    return Result;
+    
+  case ISD::SETCC:
+    abort();
+    
+  case ISD::CopyFromReg:
+    if (Result == 1)
+      Result = ExprMap[N.getValue(0)] = MakeReg(N.getValue(0).getValueType());
+    Tmp1 = dyn_cast<RegSDNode>(Node)->getReg();
+    BuildMI(BB, PPC::OR, 2, Result).addReg(Tmp1).addReg(Tmp1);
+    return Result;
+
+  case ISD::SHL:
+  case ISD::SRL:
+  case ISD::SRA:
+  case ISD::MUL:
+    abort();
+    
+  case ISD::ADD:
+    assert (DestType == MVT::i32 && "Only do arithmetic on i32s!");
+    Tmp1 = SelectExpr(N.getOperand(0));
+    switch(canUseAsImmediateForOpcode(N.getOperand(1), opcode, Tmp2)) {
+      default: assert(0 && "unhandled result code");
+      case 0: // No immediate
+        Tmp2 = SelectExpr(N.getOperand(1));
+        BuildMI(BB, PPC::ADD, 2, Result).addReg(Tmp1).addReg(Tmp2);
+        break;
+      case 1: // Low immediate
+        BuildMI(BB, PPC::ADDI, 2, Result).addReg(Tmp1).addSImm(Tmp2);
+        break;
+      case 2: // Shifted immediate
+        BuildMI(BB, PPC::ADDIS, 2, Result).addReg(Tmp1).addSImm(Tmp2);
+        break;
+    }
+    return Result;
+    
+  case ISD::SUB:
+    abort();
+ 
+  case ISD::AND:
+  case ISD::OR:
+  case ISD::XOR:
+    assert (DestType == MVT::i32 && "Only do arithmetic on i32s!");
+    Tmp1 = SelectExpr(N.getOperand(0));
+    switch(canUseAsImmediateForOpcode(N.getOperand(1), opcode, Tmp2)) {
+      default: assert(0 && "unhandled result code");
+      case 0: // No immediate
+        Tmp2 = SelectExpr(N.getOperand(1));
+        switch (opcode) {
+        case ISD::AND: Tmp3 = PPC::AND; break;
+        case ISD::OR:  Tmp3 = PPC::OR;  break;
+        case ISD::XOR: Tmp3 = PPC::XOR; break;
+        }
+        BuildMI(BB, Tmp3, 2, Result).addReg(Tmp1).addReg(Tmp2);
+        break;
+      case 1: // Low immediate
+        switch (opcode) {
+        case ISD::AND: Tmp3 = PPC::ANDIo; break;
+        case ISD::OR:  Tmp3 = PPC::ORI;   break;
+        case ISD::XOR: Tmp3 = PPC::XORI;  break;
+        }
+        BuildMI(BB, Tmp3, 2, Result).addReg(Tmp1).addImm(Tmp2);
+        break;
+      case 2: // Shifted immediate
+        switch (opcode) {
+        case ISD::AND: Tmp3 = PPC::ANDISo;  break;
+        case ISD::OR:  Tmp3 = PPC::ORIS;    break;
+        case ISD::XOR: Tmp3 = PPC::XORIS;   break;
+        }
+        BuildMI(BB, Tmp3, 2, Result).addReg(Tmp1).addImm(Tmp2);
+        break;
+    }
+    return Result;
+    
+  case ISD::UREM:
+  case ISD::SREM:
+  case ISD::SDIV:
+  case ISD::UDIV:
+    abort();
+
+  case ISD::FP_TO_UINT:
+  case ISD::FP_TO_SINT:
+    abort();
+ 
+  case ISD::SELECT:
+    abort();
+
+  case ISD::Constant:
+    switch (N.getValueType()) {
+    default: assert(0 && "Cannot use constants of this type!");
+    case MVT::i1:
+      BuildMI(BB, PPC::LI, 1, Result)
+        .addSImm(!cast<ConstantSDNode>(N)->isNullValue());
+      break;
+    case MVT::i32:
+      {
+        int v = (int)cast<ConstantSDNode>(N)->getSignExtended();
+        if (v < 32768 && v >= -32768) {
+          BuildMI(BB, PPC::LI, 1, Result).addSImm(v);
+        } else {
+          unsigned Temp = MakeReg(MVT::i32);
+          BuildMI(BB, PPC::LIS, 1, Temp).addSImm(v >> 16);
+          BuildMI(BB, PPC::ORI, 2, Result).addReg(Temp).addImm(v & 0xFFFF);
+        }
+      }
+    }
+    return Result;
+  }
+
+  return 0;
+}
+
+void ISel::Select(SDOperand N) {
+  unsigned Tmp1, Tmp2, Opc;
+  unsigned opcode = N.getOpcode();
+
+  if (!ExprMap.insert(std::make_pair(N, 1)).second)
+    return;  // Already selected.
+
+  SDNode *Node = N.Val;
+  
+  switch (Node->getOpcode()) {
+  default:
+    Node->dump(); std::cerr << "\n";
+    assert(0 && "Node not handled yet!");
+  case ISD::EntryToken: return;  // Noop
+  case ISD::TokenFactor:
+    for (unsigned i = 0, e = Node->getNumOperands(); i != e; ++i)
+      Select(Node->getOperand(i));
+    return;
+  case ISD::ADJCALLSTACKDOWN:
+  case ISD::ADJCALLSTACKUP:
+    Select(N.getOperand(0));
+    Tmp1 = cast<ConstantSDNode>(N.getOperand(1))->getValue();
+    Opc = N.getOpcode() == ISD::ADJCALLSTACKDOWN ? PPC::ADJCALLSTACKDOWN :
+      PPC::ADJCALLSTACKUP;
+    BuildMI(BB, Opc, 1).addImm(Tmp1);
+    return;
+  case ISD::BR: {
+    MachineBasicBlock *Dest =
+      cast<BasicBlockSDNode>(N.getOperand(1))->getBasicBlock();
+
+    Select(N.getOperand(0));
+    BuildMI(BB, PPC::B, 1).addMBB(Dest);
+    return;
+  }
+  case ISD::BRCOND: 
+    SelectBranchCC(N);
+    return;
+  case ISD::CopyToReg:
+    Select(N.getOperand(0));
+    Tmp1 = SelectExpr(N.getOperand(1));
+    Tmp2 = cast<RegSDNode>(N)->getReg();
+    
+    if (Tmp1 != Tmp2) {
+      if (N.getOperand(1).getValueType() == MVT::f64 || 
+          N.getOperand(1).getValueType() == MVT::f32)
+        BuildMI(BB, PPC::FMR, 1, Tmp2).addReg(Tmp1);
+      else
+        BuildMI(BB, PPC::OR, 2, Tmp2).addReg(Tmp1).addReg(Tmp1);
+    }
+    return;
+  case ISD::ImplicitDef:
+    Select(N.getOperand(0));
+    BuildMI(BB, PPC::IMPLICIT_DEF, 0, cast<RegSDNode>(N)->getReg());
+    return;
+  case ISD::RET:
+    switch (N.getNumOperands()) {
+    default:
+      assert(0 && "Unknown return instruction!");
+    case 3:
+      assert(N.getOperand(1).getValueType() == MVT::i32 &&
+             N.getOperand(2).getValueType() == MVT::i32 &&
+	           "Unknown two-register value!");
+      Select(N.getOperand(0));
+      Tmp1 = SelectExpr(N.getOperand(1));
+      Tmp2 = SelectExpr(N.getOperand(2));
+      BuildMI(BB, PPC::OR, 2, PPC::R3).addReg(Tmp1).addReg(Tmp1);
+      BuildMI(BB, PPC::OR, 2, PPC::R4).addReg(Tmp2).addReg(Tmp2);
+      break;
+    case 2:
+      Select(N.getOperand(0));
+      Tmp1 = SelectExpr(N.getOperand(1));
+      switch (N.getOperand(1).getValueType()) {
+        default:
+          assert(0 && "Unknown return type!");
+        case MVT::f64:
+        case MVT::f32:
+          BuildMI(BB, PPC::FMR, 1, PPC::F1).addReg(Tmp1);
+          break;
+        case MVT::i32:
+          BuildMI(BB, PPC::OR, 2, PPC::R3).addReg(Tmp1).addReg(Tmp1);
+          break;
+      }
+    }
+    BuildMI(BB, PPC::BLR, 0); // Just emit a 'ret' instruction
+    return;
+
+  case ISD::TRUNCSTORE: 
+  case ISD::STORE: 
+    {
+      SDOperand Chain   = N.getOperand(0);
+      SDOperand Value   = N.getOperand(1);
+      SDOperand Address = N.getOperand(2);
+      Select(Chain);
+
+      Tmp1 = SelectExpr(Value); //value
+
+      if (opcode == ISD::STORE) {
+        switch(Value.getValueType()) {
+        default: assert(0 && "unknown Type in store");
+        case MVT::i32: Opc = PPC::STW; break;
+        case MVT::f64: Opc = PPC::STFD; break;
+        case MVT::f32: Opc = PPC::STFS; break;
+        }
+      } else { //ISD::TRUNCSTORE
+        switch(cast<MVTSDNode>(Node)->getExtraValueType()) {
+        default: assert(0 && "unknown Type in store");
+        case MVT::i1: //FIXME: DAG does not promote this load
+        case MVT::i8: Opc  = PPC::STB; break;
+        case MVT::i16: Opc = PPC::STH; break;
+        }
+      }
+
+      if (Address.getOpcode() == ISD::GlobalAddress)
+      {
+        BuildMI(BB, Opc, 2).addReg(Tmp1)
+          .addGlobalAddress(cast<GlobalAddressSDNode>(Address)->getGlobal());
+      }
+      else if(Address.getOpcode() == ISD::FrameIndex)
+      {
+        BuildMI(BB, Opc, 2).addReg(Tmp1)
+          .addFrameIndex(cast<FrameIndexSDNode>(Address)->getIndex());
+      }
+      else
+      {
+        int offset;
+        SelectAddr(Address, Tmp2, offset);
+        BuildMI(BB, Opc, 3).addReg(Tmp1).addImm(offset).addReg(Tmp2);
+      }
+      return;
+    }
+  case ISD::EXTLOAD:
+  case ISD::SEXTLOAD:
+  case ISD::ZEXTLOAD:
+  case ISD::LOAD:
+  case ISD::CopyFromReg:
+  case ISD::CALL:
+  case ISD::DYNAMIC_STACKALLOC:
+    ExprMap.erase(N);
+    SelectExpr(N);
+    return;
+  }
+  assert(0 && "Should not be reached!");
+}
+
+
+/// createPPC32PatternInstructionSelector - This pass converts an LLVM function
+/// into a machine code representation using pattern matching and a machine
+/// description file.
+///
+FunctionPass *llvm::createPPC32ISelPattern(TargetMachine &TM) {
+  return new ISel(TM);  
+}
\ No newline at end of file
diff --git a/llvm/lib/Target/PowerPC/PowerPC.h b/llvm/lib/Target/PowerPC/PowerPC.h
index 7ca87d9ba52..bd1f2ac8ce5 100644
--- a/llvm/lib/Target/PowerPC/PowerPC.h
+++ b/llvm/lib/Target/PowerPC/PowerPC.h
@@ -24,6 +24,7 @@ class TargetMachine;
 
 FunctionPass *createPPCBranchSelectionPass();
 FunctionPass *createPPC32ISelSimple(TargetMachine &TM);
+FunctionPass *createPPC32ISelPattern(TargetMachine &TM);
 FunctionPass *createPPC64ISelSimple(TargetMachine &TM);
 FunctionPass *createDarwinAsmPrinter(std::ostream &OS, TargetMachine &TM);
 FunctionPass *createAIXAsmPrinter(std::ostream &OS, TargetMachine &TM);
diff --git a/llvm/lib/Target/PowerPC/PowerPCTargetMachine.cpp b/llvm/lib/Target/PowerPC/PowerPCTargetMachine.cpp
index dd40e1333c7..75f1fc36371 100644
--- a/llvm/lib/Target/PowerPC/PowerPCTargetMachine.cpp
+++ b/llvm/lib/Target/PowerPC/PowerPCTargetMachine.cpp
@@ -37,6 +37,8 @@ namespace llvm {
   cl::opt<bool> EnablePPCLSR("enable-lsr-for-ppc", 
                              cl::desc("Enable LSR for PPC (beta option!)"), 
                              cl::Hidden);
+  cl::opt<bool> EnablePatternISel("pattern-isel", cl::Hidden,
+                                cl::desc("Enable the pattern isel XXX FIXME"));
 }
 
 namespace {
@@ -96,6 +98,8 @@ bool PowerPCTargetMachine::addPassesToEmitAssembly(PassManager &PM,
 
   if (LP64)
     PM.add(createPPC64ISelSimple(*this));
+  else if (EnablePatternISel)
+    PM.add(createPPC32ISelPattern(*this));
   else
     PM.add(createPPC32ISelSimple(*this));