Check in LLVM r95781.
diff --git a/lib/Target/X86/X86FloatingPoint.cpp b/lib/Target/X86/X86FloatingPoint.cpp
new file mode 100644
index 0000000..6d6fe77
--- /dev/null
+++ b/lib/Target/X86/X86FloatingPoint.cpp
@@ -0,0 +1,1207 @@
+//===-- X86FloatingPoint.cpp - Floating point Reg -> Stack converter ------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the pass which converts floating point instructions from
+// virtual registers into register stack instructions.  This pass uses live
+// variable information to indicate where the FPn registers are used and their
+// lifetimes.
+//
+// This pass is hampered by the lack of decent CFG manipulation routines for
+// machine code.  In particular, this wants to be able to split critical edges
+// as necessary, traverse the machine basic block CFG in depth-first order, and
+// allow there to be multiple machine basic blocks for each LLVM basicblock
+// (needed for critical edge splitting).
+//
+// In particular, this pass currently barfs on critical edges.  Because of this,
+// it requires the instruction selector to insert FP_REG_KILL instructions on
+// the exits of any basic block that has critical edges going from it, or which
+// branch to a critical basic block.
+//
+// FIXME: this is not implemented yet.  The stackifier pass only works on local
+// basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "x86-codegen"
+#include "X86.h"
+#include "X86InstrInfo.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include <algorithm>
+using namespace llvm;
+
+STATISTIC(NumFXCH, "Number of fxch instructions inserted");
+STATISTIC(NumFP  , "Number of floating point instructions");
+
+namespace {
+  struct FPS : public MachineFunctionPass {
+    static char ID;
+    FPS() : MachineFunctionPass(&ID) {}
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+      AU.addPreservedID(MachineLoopInfoID);
+      AU.addPreservedID(MachineDominatorsID);
+      MachineFunctionPass::getAnalysisUsage(AU);
+    }
+
+    virtual bool runOnMachineFunction(MachineFunction &MF);
+
+    virtual const char *getPassName() const { return "X86 FP Stackifier"; }
+
+  private:
+    const TargetInstrInfo *TII; // Machine instruction info.
+    MachineBasicBlock *MBB;     // Current basic block
+    unsigned Stack[8];          // FP<n> Registers in each stack slot...
+    unsigned RegMap[8];         // Track which stack slot contains each register
+    unsigned StackTop;          // The current top of the FP stack.
+
+    void dumpStack() const {
+      dbgs() << "Stack contents:";
+      for (unsigned i = 0; i != StackTop; ++i) {
+        dbgs() << " FP" << Stack[i];
+        assert(RegMap[Stack[i]] == i && "Stack[] doesn't match RegMap[]!");
+      }
+      dbgs() << "\n";
+    }
+  private:
+    /// isStackEmpty - Return true if the FP stack is empty.
+    bool isStackEmpty() const {
+      return StackTop == 0;
+    }
+    
+    // getSlot - Return the stack slot number a particular register number is
+    // in.
+    unsigned getSlot(unsigned RegNo) const {
+      assert(RegNo < 8 && "Regno out of range!");
+      return RegMap[RegNo];
+    }
+
+    // getStackEntry - Return the X86::FP<n> register in register ST(i).
+    unsigned getStackEntry(unsigned STi) const {
+      assert(STi < StackTop && "Access past stack top!");
+      return Stack[StackTop-1-STi];
+    }
+
+    // getSTReg - Return the X86::ST(i) register which contains the specified
+    // FP<RegNo> register.
+    unsigned getSTReg(unsigned RegNo) const {
+      return StackTop - 1 - getSlot(RegNo) + llvm::X86::ST0;
+    }
+
+    // pushReg - Push the specified FP<n> register onto the stack.
+    void pushReg(unsigned Reg) {
+      assert(Reg < 8 && "Register number out of range!");
+      assert(StackTop < 8 && "Stack overflow!");
+      Stack[StackTop] = Reg;
+      RegMap[Reg] = StackTop++;
+    }
+
+    bool isAtTop(unsigned RegNo) const { return getSlot(RegNo) == StackTop-1; }
+    void moveToTop(unsigned RegNo, MachineBasicBlock::iterator I) {
+      MachineInstr *MI = I;
+      DebugLoc dl = MI->getDebugLoc();
+      if (isAtTop(RegNo)) return;
+      
+      unsigned STReg = getSTReg(RegNo);
+      unsigned RegOnTop = getStackEntry(0);
+
+      // Swap the slots the regs are in.
+      std::swap(RegMap[RegNo], RegMap[RegOnTop]);
+
+      // Swap stack slot contents.
+      assert(RegMap[RegOnTop] < StackTop);
+      std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
+
+      // Emit an fxch to update the runtime processors version of the state.
+      BuildMI(*MBB, I, dl, TII->get(X86::XCH_F)).addReg(STReg);
+      NumFXCH++;
+    }
+
+    void duplicateToTop(unsigned RegNo, unsigned AsReg, MachineInstr *I) {
+      DebugLoc dl = I->getDebugLoc();
+      unsigned STReg = getSTReg(RegNo);
+      pushReg(AsReg);   // New register on top of stack
+
+      BuildMI(*MBB, I, dl, TII->get(X86::LD_Frr)).addReg(STReg);
+    }
+
+    // popStackAfter - Pop the current value off of the top of the FP stack
+    // after the specified instruction.
+    void popStackAfter(MachineBasicBlock::iterator &I);
+
+    // freeStackSlotAfter - Free the specified register from the register stack,
+    // so that it is no longer in a register.  If the register is currently at
+    // the top of the stack, we just pop the current instruction, otherwise we
+    // store the current top-of-stack into the specified slot, then pop the top
+    // of stack.
+    void freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned Reg);
+
+    bool processBasicBlock(MachineFunction &MF, MachineBasicBlock &MBB);
+
+    void handleZeroArgFP(MachineBasicBlock::iterator &I);
+    void handleOneArgFP(MachineBasicBlock::iterator &I);
+    void handleOneArgFPRW(MachineBasicBlock::iterator &I);
+    void handleTwoArgFP(MachineBasicBlock::iterator &I);
+    void handleCompareFP(MachineBasicBlock::iterator &I);
+    void handleCondMovFP(MachineBasicBlock::iterator &I);
+    void handleSpecialFP(MachineBasicBlock::iterator &I);
+  };
+  char FPS::ID = 0;
+}
+
+FunctionPass *llvm::createX86FloatingPointStackifierPass() { return new FPS(); }
+
+/// getFPReg - Return the X86::FPx register number for the specified operand.
+/// For example, this returns 3 for X86::FP3.
+static unsigned getFPReg(const MachineOperand &MO) {
+  assert(MO.isReg() && "Expected an FP register!");
+  unsigned Reg = MO.getReg();
+  assert(Reg >= X86::FP0 && Reg <= X86::FP6 && "Expected FP register!");
+  return Reg - X86::FP0;
+}
+
+
+/// runOnMachineFunction - Loop over all of the basic blocks, transforming FP
+/// register references into FP stack references.
+///
+bool FPS::runOnMachineFunction(MachineFunction &MF) {
+  // We only need to run this pass if there are any FP registers used in this
+  // function.  If it is all integer, there is nothing for us to do!
+  bool FPIsUsed = false;
+
+  assert(X86::FP6 == X86::FP0+6 && "Register enums aren't sorted right!");
+  for (unsigned i = 0; i <= 6; ++i)
+    if (MF.getRegInfo().isPhysRegUsed(X86::FP0+i)) {
+      FPIsUsed = true;
+      break;
+    }
+
+  // Early exit.
+  if (!FPIsUsed) return false;
+
+  TII = MF.getTarget().getInstrInfo();
+  StackTop = 0;
+
+  // Process the function in depth first order so that we process at least one
+  // of the predecessors for every reachable block in the function.
+  SmallPtrSet<MachineBasicBlock*, 8> Processed;
+  MachineBasicBlock *Entry = MF.begin();
+
+  bool Changed = false;
+  for (df_ext_iterator<MachineBasicBlock*, SmallPtrSet<MachineBasicBlock*, 8> >
+         I = df_ext_begin(Entry, Processed), E = df_ext_end(Entry, Processed);
+       I != E; ++I)
+    Changed |= processBasicBlock(MF, **I);
+
+  // Process any unreachable blocks in arbitrary order now.
+  if (MF.size() == Processed.size())
+    return Changed;
+
+  for (MachineFunction::iterator BB = MF.begin(), E = MF.end(); BB != E; ++BB)
+    if (Processed.insert(BB))
+      Changed |= processBasicBlock(MF, *BB);
+  
+  return Changed;
+}
+
+/// processBasicBlock - Loop over all of the instructions in the basic block,
+/// transforming FP instructions into their stack form.
+///
+bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
+  bool Changed = false;
+  MBB = &BB;
+
+  for (MachineBasicBlock::iterator I = BB.begin(); I != BB.end(); ++I) {
+    MachineInstr *MI = I;
+    unsigned Flags = MI->getDesc().TSFlags;
+    
+    unsigned FPInstClass = Flags & X86II::FPTypeMask;
+    if (MI->isInlineAsm())
+      FPInstClass = X86II::SpecialFP;
+    
+    if (FPInstClass == X86II::NotFP)
+      continue;  // Efficiently ignore non-fp insts!
+
+    MachineInstr *PrevMI = 0;
+    if (I != BB.begin())
+      PrevMI = prior(I);
+
+    ++NumFP;  // Keep track of # of pseudo instrs
+    DEBUG(dbgs() << "\nFPInst:\t" << *MI);
+
+    // Get dead variables list now because the MI pointer may be deleted as part
+    // of processing!
+    SmallVector<unsigned, 8> DeadRegs;
+    for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+      const MachineOperand &MO = MI->getOperand(i);
+      if (MO.isReg() && MO.isDead())
+        DeadRegs.push_back(MO.getReg());
+    }
+
+    switch (FPInstClass) {
+    case X86II::ZeroArgFP:  handleZeroArgFP(I); break;
+    case X86II::OneArgFP:   handleOneArgFP(I);  break;  // fstp ST(0)
+    case X86II::OneArgFPRW: handleOneArgFPRW(I); break; // ST(0) = fsqrt(ST(0))
+    case X86II::TwoArgFP:   handleTwoArgFP(I);  break;
+    case X86II::CompareFP:  handleCompareFP(I); break;
+    case X86II::CondMovFP:  handleCondMovFP(I); break;
+    case X86II::SpecialFP:  handleSpecialFP(I); break;
+    default: llvm_unreachable("Unknown FP Type!");
+    }
+
+    // Check to see if any of the values defined by this instruction are dead
+    // after definition.  If so, pop them.
+    for (unsigned i = 0, e = DeadRegs.size(); i != e; ++i) {
+      unsigned Reg = DeadRegs[i];
+      if (Reg >= X86::FP0 && Reg <= X86::FP6) {
+        DEBUG(dbgs() << "Register FP#" << Reg-X86::FP0 << " is dead!\n");
+        freeStackSlotAfter(I, Reg-X86::FP0);
+      }
+    }
+
+    // Print out all of the instructions expanded to if -debug
+    DEBUG(
+      MachineBasicBlock::iterator PrevI(PrevMI);
+      if (I == PrevI) {
+        dbgs() << "Just deleted pseudo instruction\n";
+      } else {
+        MachineBasicBlock::iterator Start = I;
+        // Rewind to first instruction newly inserted.
+        while (Start != BB.begin() && prior(Start) != PrevI) --Start;
+        dbgs() << "Inserted instructions:\n\t";
+        Start->print(dbgs(), &MF.getTarget());
+        while (++Start != llvm::next(I)) {}
+      }
+      dumpStack();
+    );
+
+    Changed = true;
+  }
+
+  assert(isStackEmpty() && "Stack not empty at end of basic block?");
+  return Changed;
+}
+
+//===----------------------------------------------------------------------===//
+// Efficient Lookup Table Support
+//===----------------------------------------------------------------------===//
+
+namespace {
+  struct TableEntry {
+    unsigned from;
+    unsigned to;
+    bool operator<(const TableEntry &TE) const { return from < TE.from; }
+    friend bool operator<(const TableEntry &TE, unsigned V) {
+      return TE.from < V;
+    }
+    friend bool operator<(unsigned V, const TableEntry &TE) {
+      return V < TE.from;
+    }
+  };
+}
+
+#ifndef NDEBUG
+static bool TableIsSorted(const TableEntry *Table, unsigned NumEntries) {
+  for (unsigned i = 0; i != NumEntries-1; ++i)
+    if (!(Table[i] < Table[i+1])) return false;
+  return true;
+}
+#endif
+
+static int Lookup(const TableEntry *Table, unsigned N, unsigned Opcode) {
+  const TableEntry *I = std::lower_bound(Table, Table+N, Opcode);
+  if (I != Table+N && I->from == Opcode)
+    return I->to;
+  return -1;
+}
+
+#ifdef NDEBUG
+#define ASSERT_SORTED(TABLE)
+#else
+#define ASSERT_SORTED(TABLE)                                              \
+  { static bool TABLE##Checked = false;                                   \
+    if (!TABLE##Checked) {                                                \
+       assert(TableIsSorted(TABLE, array_lengthof(TABLE)) &&              \
+              "All lookup tables must be sorted for efficient access!");  \
+       TABLE##Checked = true;                                             \
+    }                                                                     \
+  }
+#endif
+
+//===----------------------------------------------------------------------===//
+// Register File -> Register Stack Mapping Methods
+//===----------------------------------------------------------------------===//
+
+// OpcodeTable - Sorted map of register instructions to their stack version.
+// The first element is an register file pseudo instruction, the second is the
+// concrete X86 instruction which uses the register stack.
+//
+static const TableEntry OpcodeTable[] = {
+  { X86::ABS_Fp32     , X86::ABS_F     },
+  { X86::ABS_Fp64     , X86::ABS_F     },
+  { X86::ABS_Fp80     , X86::ABS_F     },
+  { X86::ADD_Fp32m    , X86::ADD_F32m  },
+  { X86::ADD_Fp64m    , X86::ADD_F64m  },
+  { X86::ADD_Fp64m32  , X86::ADD_F32m  },
+  { X86::ADD_Fp80m32  , X86::ADD_F32m  },
+  { X86::ADD_Fp80m64  , X86::ADD_F64m  },
+  { X86::ADD_FpI16m32 , X86::ADD_FI16m },
+  { X86::ADD_FpI16m64 , X86::ADD_FI16m },
+  { X86::ADD_FpI16m80 , X86::ADD_FI16m },
+  { X86::ADD_FpI32m32 , X86::ADD_FI32m },
+  { X86::ADD_FpI32m64 , X86::ADD_FI32m },
+  { X86::ADD_FpI32m80 , X86::ADD_FI32m },
+  { X86::CHS_Fp32     , X86::CHS_F     },
+  { X86::CHS_Fp64     , X86::CHS_F     },
+  { X86::CHS_Fp80     , X86::CHS_F     },
+  { X86::CMOVBE_Fp32  , X86::CMOVBE_F  },
+  { X86::CMOVBE_Fp64  , X86::CMOVBE_F  },
+  { X86::CMOVBE_Fp80  , X86::CMOVBE_F  },
+  { X86::CMOVB_Fp32   , X86::CMOVB_F   },
+  { X86::CMOVB_Fp64   , X86::CMOVB_F  },
+  { X86::CMOVB_Fp80   , X86::CMOVB_F  },
+  { X86::CMOVE_Fp32   , X86::CMOVE_F  },
+  { X86::CMOVE_Fp64   , X86::CMOVE_F   },
+  { X86::CMOVE_Fp80   , X86::CMOVE_F   },
+  { X86::CMOVNBE_Fp32 , X86::CMOVNBE_F },
+  { X86::CMOVNBE_Fp64 , X86::CMOVNBE_F },
+  { X86::CMOVNBE_Fp80 , X86::CMOVNBE_F },
+  { X86::CMOVNB_Fp32  , X86::CMOVNB_F  },
+  { X86::CMOVNB_Fp64  , X86::CMOVNB_F  },
+  { X86::CMOVNB_Fp80  , X86::CMOVNB_F  },
+  { X86::CMOVNE_Fp32  , X86::CMOVNE_F  },
+  { X86::CMOVNE_Fp64  , X86::CMOVNE_F  },
+  { X86::CMOVNE_Fp80  , X86::CMOVNE_F  },
+  { X86::CMOVNP_Fp32  , X86::CMOVNP_F  },
+  { X86::CMOVNP_Fp64  , X86::CMOVNP_F  },
+  { X86::CMOVNP_Fp80  , X86::CMOVNP_F  },
+  { X86::CMOVP_Fp32   , X86::CMOVP_F   },
+  { X86::CMOVP_Fp64   , X86::CMOVP_F   },
+  { X86::CMOVP_Fp80   , X86::CMOVP_F   },
+  { X86::COS_Fp32     , X86::COS_F     },
+  { X86::COS_Fp64     , X86::COS_F     },
+  { X86::COS_Fp80     , X86::COS_F     },
+  { X86::DIVR_Fp32m   , X86::DIVR_F32m },
+  { X86::DIVR_Fp64m   , X86::DIVR_F64m },
+  { X86::DIVR_Fp64m32 , X86::DIVR_F32m },
+  { X86::DIVR_Fp80m32 , X86::DIVR_F32m },
+  { X86::DIVR_Fp80m64 , X86::DIVR_F64m },
+  { X86::DIVR_FpI16m32, X86::DIVR_FI16m},
+  { X86::DIVR_FpI16m64, X86::DIVR_FI16m},
+  { X86::DIVR_FpI16m80, X86::DIVR_FI16m},
+  { X86::DIVR_FpI32m32, X86::DIVR_FI32m},
+  { X86::DIVR_FpI32m64, X86::DIVR_FI32m},
+  { X86::DIVR_FpI32m80, X86::DIVR_FI32m},
+  { X86::DIV_Fp32m    , X86::DIV_F32m  },
+  { X86::DIV_Fp64m    , X86::DIV_F64m  },
+  { X86::DIV_Fp64m32  , X86::DIV_F32m  },
+  { X86::DIV_Fp80m32  , X86::DIV_F32m  },
+  { X86::DIV_Fp80m64  , X86::DIV_F64m  },
+  { X86::DIV_FpI16m32 , X86::DIV_FI16m },
+  { X86::DIV_FpI16m64 , X86::DIV_FI16m },
+  { X86::DIV_FpI16m80 , X86::DIV_FI16m },
+  { X86::DIV_FpI32m32 , X86::DIV_FI32m },
+  { X86::DIV_FpI32m64 , X86::DIV_FI32m },
+  { X86::DIV_FpI32m80 , X86::DIV_FI32m },
+  { X86::ILD_Fp16m32  , X86::ILD_F16m  },
+  { X86::ILD_Fp16m64  , X86::ILD_F16m  },
+  { X86::ILD_Fp16m80  , X86::ILD_F16m  },
+  { X86::ILD_Fp32m32  , X86::ILD_F32m  },
+  { X86::ILD_Fp32m64  , X86::ILD_F32m  },
+  { X86::ILD_Fp32m80  , X86::ILD_F32m  },
+  { X86::ILD_Fp64m32  , X86::ILD_F64m  },
+  { X86::ILD_Fp64m64  , X86::ILD_F64m  },
+  { X86::ILD_Fp64m80  , X86::ILD_F64m  },
+  { X86::ISTT_Fp16m32 , X86::ISTT_FP16m},
+  { X86::ISTT_Fp16m64 , X86::ISTT_FP16m},
+  { X86::ISTT_Fp16m80 , X86::ISTT_FP16m},
+  { X86::ISTT_Fp32m32 , X86::ISTT_FP32m},
+  { X86::ISTT_Fp32m64 , X86::ISTT_FP32m},
+  { X86::ISTT_Fp32m80 , X86::ISTT_FP32m},
+  { X86::ISTT_Fp64m32 , X86::ISTT_FP64m},
+  { X86::ISTT_Fp64m64 , X86::ISTT_FP64m},
+  { X86::ISTT_Fp64m80 , X86::ISTT_FP64m},
+  { X86::IST_Fp16m32  , X86::IST_F16m  },
+  { X86::IST_Fp16m64  , X86::IST_F16m  },
+  { X86::IST_Fp16m80  , X86::IST_F16m  },
+  { X86::IST_Fp32m32  , X86::IST_F32m  },
+  { X86::IST_Fp32m64  , X86::IST_F32m  },
+  { X86::IST_Fp32m80  , X86::IST_F32m  },
+  { X86::IST_Fp64m32  , X86::IST_FP64m },
+  { X86::IST_Fp64m64  , X86::IST_FP64m },
+  { X86::IST_Fp64m80  , X86::IST_FP64m },
+  { X86::LD_Fp032     , X86::LD_F0     },
+  { X86::LD_Fp064     , X86::LD_F0     },
+  { X86::LD_Fp080     , X86::LD_F0     },
+  { X86::LD_Fp132     , X86::LD_F1     },
+  { X86::LD_Fp164     , X86::LD_F1     },
+  { X86::LD_Fp180     , X86::LD_F1     },
+  { X86::LD_Fp32m     , X86::LD_F32m   },
+  { X86::LD_Fp32m64   , X86::LD_F32m   },
+  { X86::LD_Fp32m80   , X86::LD_F32m   },
+  { X86::LD_Fp64m     , X86::LD_F64m   },
+  { X86::LD_Fp64m80   , X86::LD_F64m   },
+  { X86::LD_Fp80m     , X86::LD_F80m   },
+  { X86::MUL_Fp32m    , X86::MUL_F32m  },
+  { X86::MUL_Fp64m    , X86::MUL_F64m  },
+  { X86::MUL_Fp64m32  , X86::MUL_F32m  },
+  { X86::MUL_Fp80m32  , X86::MUL_F32m  },
+  { X86::MUL_Fp80m64  , X86::MUL_F64m  },
+  { X86::MUL_FpI16m32 , X86::MUL_FI16m },
+  { X86::MUL_FpI16m64 , X86::MUL_FI16m },
+  { X86::MUL_FpI16m80 , X86::MUL_FI16m },
+  { X86::MUL_FpI32m32 , X86::MUL_FI32m },
+  { X86::MUL_FpI32m64 , X86::MUL_FI32m },
+  { X86::MUL_FpI32m80 , X86::MUL_FI32m },
+  { X86::SIN_Fp32     , X86::SIN_F     },
+  { X86::SIN_Fp64     , X86::SIN_F     },
+  { X86::SIN_Fp80     , X86::SIN_F     },
+  { X86::SQRT_Fp32    , X86::SQRT_F    },
+  { X86::SQRT_Fp64    , X86::SQRT_F    },
+  { X86::SQRT_Fp80    , X86::SQRT_F    },
+  { X86::ST_Fp32m     , X86::ST_F32m   },
+  { X86::ST_Fp64m     , X86::ST_F64m   },
+  { X86::ST_Fp64m32   , X86::ST_F32m   },
+  { X86::ST_Fp80m32   , X86::ST_F32m   },
+  { X86::ST_Fp80m64   , X86::ST_F64m   },
+  { X86::ST_FpP80m    , X86::ST_FP80m  },
+  { X86::SUBR_Fp32m   , X86::SUBR_F32m },
+  { X86::SUBR_Fp64m   , X86::SUBR_F64m },
+  { X86::SUBR_Fp64m32 , X86::SUBR_F32m },
+  { X86::SUBR_Fp80m32 , X86::SUBR_F32m },
+  { X86::SUBR_Fp80m64 , X86::SUBR_F64m },
+  { X86::SUBR_FpI16m32, X86::SUBR_FI16m},
+  { X86::SUBR_FpI16m64, X86::SUBR_FI16m},
+  { X86::SUBR_FpI16m80, X86::SUBR_FI16m},
+  { X86::SUBR_FpI32m32, X86::SUBR_FI32m},
+  { X86::SUBR_FpI32m64, X86::SUBR_FI32m},
+  { X86::SUBR_FpI32m80, X86::SUBR_FI32m},
+  { X86::SUB_Fp32m    , X86::SUB_F32m  },
+  { X86::SUB_Fp64m    , X86::SUB_F64m  },
+  { X86::SUB_Fp64m32  , X86::SUB_F32m  },
+  { X86::SUB_Fp80m32  , X86::SUB_F32m  },
+  { X86::SUB_Fp80m64  , X86::SUB_F64m  },
+  { X86::SUB_FpI16m32 , X86::SUB_FI16m },
+  { X86::SUB_FpI16m64 , X86::SUB_FI16m },
+  { X86::SUB_FpI16m80 , X86::SUB_FI16m },
+  { X86::SUB_FpI32m32 , X86::SUB_FI32m },
+  { X86::SUB_FpI32m64 , X86::SUB_FI32m },
+  { X86::SUB_FpI32m80 , X86::SUB_FI32m },
+  { X86::TST_Fp32     , X86::TST_F     },
+  { X86::TST_Fp64     , X86::TST_F     },
+  { X86::TST_Fp80     , X86::TST_F     },
+  { X86::UCOM_FpIr32  , X86::UCOM_FIr  },
+  { X86::UCOM_FpIr64  , X86::UCOM_FIr  },
+  { X86::UCOM_FpIr80  , X86::UCOM_FIr  },
+  { X86::UCOM_Fpr32   , X86::UCOM_Fr   },
+  { X86::UCOM_Fpr64   , X86::UCOM_Fr   },
+  { X86::UCOM_Fpr80   , X86::UCOM_Fr   },
+};
+
+static unsigned getConcreteOpcode(unsigned Opcode) {
+  ASSERT_SORTED(OpcodeTable);
+  int Opc = Lookup(OpcodeTable, array_lengthof(OpcodeTable), Opcode);
+  assert(Opc != -1 && "FP Stack instruction not in OpcodeTable!");
+  return Opc;
+}
+
+//===----------------------------------------------------------------------===//
+// Helper Methods
+//===----------------------------------------------------------------------===//
+
+// PopTable - Sorted map of instructions to their popping version.  The first
+// element is an instruction, the second is the version which pops.
+//
+static const TableEntry PopTable[] = {
+  { X86::ADD_FrST0 , X86::ADD_FPrST0  },
+
+  { X86::DIVR_FrST0, X86::DIVR_FPrST0 },
+  { X86::DIV_FrST0 , X86::DIV_FPrST0  },
+
+  { X86::IST_F16m  , X86::IST_FP16m   },
+  { X86::IST_F32m  , X86::IST_FP32m   },
+
+  { X86::MUL_FrST0 , X86::MUL_FPrST0  },
+
+  { X86::ST_F32m   , X86::ST_FP32m    },
+  { X86::ST_F64m   , X86::ST_FP64m    },
+  { X86::ST_Frr    , X86::ST_FPrr     },
+
+  { X86::SUBR_FrST0, X86::SUBR_FPrST0 },
+  { X86::SUB_FrST0 , X86::SUB_FPrST0  },
+
+  { X86::UCOM_FIr  , X86::UCOM_FIPr   },
+
+  { X86::UCOM_FPr  , X86::UCOM_FPPr   },
+  { X86::UCOM_Fr   , X86::UCOM_FPr    },
+};
+
+/// popStackAfter - Pop the current value off of the top of the FP stack after
+/// the specified instruction.  This attempts to be sneaky and combine the pop
+/// into the instruction itself if possible.  The iterator is left pointing to
+/// the last instruction, be it a new pop instruction inserted, or the old
+/// instruction if it was modified in place.
+///
+void FPS::popStackAfter(MachineBasicBlock::iterator &I) {
+  MachineInstr* MI = I;
+  DebugLoc dl = MI->getDebugLoc();
+  ASSERT_SORTED(PopTable);
+  assert(StackTop > 0 && "Cannot pop empty stack!");
+  RegMap[Stack[--StackTop]] = ~0;     // Update state
+
+  // Check to see if there is a popping version of this instruction...
+  int Opcode = Lookup(PopTable, array_lengthof(PopTable), I->getOpcode());
+  if (Opcode != -1) {
+    I->setDesc(TII->get(Opcode));
+    if (Opcode == X86::UCOM_FPPr)
+      I->RemoveOperand(0);
+  } else {    // Insert an explicit pop
+    I = BuildMI(*MBB, ++I, dl, TII->get(X86::ST_FPrr)).addReg(X86::ST0);
+  }
+}
+
+/// freeStackSlotAfter - Free the specified register from the register stack, so
+/// that it is no longer in a register.  If the register is currently at the top
+/// of the stack, we just pop the current instruction, otherwise we store the
+/// current top-of-stack into the specified slot, then pop the top of stack.
+void FPS::freeStackSlotAfter(MachineBasicBlock::iterator &I, unsigned FPRegNo) {
+  if (getStackEntry(0) == FPRegNo) {  // already at the top of stack? easy.
+    popStackAfter(I);
+    return;
+  }
+
+  // Otherwise, store the top of stack into the dead slot, killing the operand
+  // without having to add in an explicit xchg then pop.
+  //
+  unsigned STReg    = getSTReg(FPRegNo);
+  unsigned OldSlot  = getSlot(FPRegNo);
+  unsigned TopReg   = Stack[StackTop-1];
+  Stack[OldSlot]    = TopReg;
+  RegMap[TopReg]    = OldSlot;
+  RegMap[FPRegNo]   = ~0;
+  Stack[--StackTop] = ~0;
+  MachineInstr *MI  = I;
+  DebugLoc dl = MI->getDebugLoc();
+  I = BuildMI(*MBB, ++I, dl, TII->get(X86::ST_FPrr)).addReg(STReg);
+}
+
+
+//===----------------------------------------------------------------------===//
+// Instruction transformation implementation
+//===----------------------------------------------------------------------===//
+
+/// handleZeroArgFP - ST(0) = fld0    ST(0) = flds <mem>
+///
+void FPS::handleZeroArgFP(MachineBasicBlock::iterator &I) {
+  MachineInstr *MI = I;
+  unsigned DestReg = getFPReg(MI->getOperand(0));
+
+  // Change from the pseudo instruction to the concrete instruction.
+  MI->RemoveOperand(0);   // Remove the explicit ST(0) operand
+  MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
+  
+  // Result gets pushed on the stack.
+  pushReg(DestReg);
+}
+
+/// handleOneArgFP - fst <mem>, ST(0)
+///
+void FPS::handleOneArgFP(MachineBasicBlock::iterator &I) {
+  MachineInstr *MI = I;
+  unsigned NumOps = MI->getDesc().getNumOperands();
+  assert((NumOps == X86AddrNumOperands + 1 || NumOps == 1) &&
+         "Can only handle fst* & ftst instructions!");
+
+  // Is this the last use of the source register?
+  unsigned Reg = getFPReg(MI->getOperand(NumOps-1));
+  bool KillsSrc = MI->killsRegister(X86::FP0+Reg);
+
+  // FISTP64m is strange because there isn't a non-popping versions.
+  // If we have one _and_ we don't want to pop the operand, duplicate the value
+  // on the stack instead of moving it.  This ensure that popping the value is
+  // always ok.
+  // Ditto FISTTP16m, FISTTP32m, FISTTP64m, ST_FpP80m.
+  //
+  if (!KillsSrc &&
+      (MI->getOpcode() == X86::IST_Fp64m32 ||
+       MI->getOpcode() == X86::ISTT_Fp16m32 ||
+       MI->getOpcode() == X86::ISTT_Fp32m32 ||
+       MI->getOpcode() == X86::ISTT_Fp64m32 ||
+       MI->getOpcode() == X86::IST_Fp64m64 ||
+       MI->getOpcode() == X86::ISTT_Fp16m64 ||
+       MI->getOpcode() == X86::ISTT_Fp32m64 ||
+       MI->getOpcode() == X86::ISTT_Fp64m64 ||
+       MI->getOpcode() == X86::IST_Fp64m80 ||
+       MI->getOpcode() == X86::ISTT_Fp16m80 ||
+       MI->getOpcode() == X86::ISTT_Fp32m80 ||
+       MI->getOpcode() == X86::ISTT_Fp64m80 ||
+       MI->getOpcode() == X86::ST_FpP80m)) {
+    duplicateToTop(Reg, 7 /*temp register*/, I);
+  } else {
+    moveToTop(Reg, I);            // Move to the top of the stack...
+  }
+  
+  // Convert from the pseudo instruction to the concrete instruction.
+  MI->RemoveOperand(NumOps-1);    // Remove explicit ST(0) operand
+  MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
+
+  if (MI->getOpcode() == X86::IST_FP64m ||
+      MI->getOpcode() == X86::ISTT_FP16m ||
+      MI->getOpcode() == X86::ISTT_FP32m ||
+      MI->getOpcode() == X86::ISTT_FP64m ||
+      MI->getOpcode() == X86::ST_FP80m) {
+    assert(StackTop > 0 && "Stack empty??");
+    --StackTop;
+  } else if (KillsSrc) { // Last use of operand?
+    popStackAfter(I);
+  }
+}
+
+
+/// handleOneArgFPRW: Handle instructions that read from the top of stack and
+/// replace the value with a newly computed value.  These instructions may have
+/// non-fp operands after their FP operands.
+///
+///  Examples:
+///     R1 = fchs R2
+///     R1 = fadd R2, [mem]
+///
+void FPS::handleOneArgFPRW(MachineBasicBlock::iterator &I) {
+  MachineInstr *MI = I;
+#ifndef NDEBUG
+  unsigned NumOps = MI->getDesc().getNumOperands();
+  assert(NumOps >= 2 && "FPRW instructions must have 2 ops!!");
+#endif
+
+  // Is this the last use of the source register?
+  unsigned Reg = getFPReg(MI->getOperand(1));
+  bool KillsSrc = MI->killsRegister(X86::FP0+Reg);
+
+  if (KillsSrc) {
+    // If this is the last use of the source register, just make sure it's on
+    // the top of the stack.
+    moveToTop(Reg, I);
+    assert(StackTop > 0 && "Stack cannot be empty!");
+    --StackTop;
+    pushReg(getFPReg(MI->getOperand(0)));
+  } else {
+    // If this is not the last use of the source register, _copy_ it to the top
+    // of the stack.
+    duplicateToTop(Reg, getFPReg(MI->getOperand(0)), I);
+  }
+
+  // Change from the pseudo instruction to the concrete instruction.
+  MI->RemoveOperand(1);   // Drop the source operand.
+  MI->RemoveOperand(0);   // Drop the destination operand.
+  MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
+}
+
+
+//===----------------------------------------------------------------------===//
+// Define tables of various ways to map pseudo instructions
+//
+
+// ForwardST0Table - Map: A = B op C  into: ST(0) = ST(0) op ST(i)
+static const TableEntry ForwardST0Table[] = {
+  { X86::ADD_Fp32  , X86::ADD_FST0r },
+  { X86::ADD_Fp64  , X86::ADD_FST0r },
+  { X86::ADD_Fp80  , X86::ADD_FST0r },
+  { X86::DIV_Fp32  , X86::DIV_FST0r },
+  { X86::DIV_Fp64  , X86::DIV_FST0r },
+  { X86::DIV_Fp80  , X86::DIV_FST0r },
+  { X86::MUL_Fp32  , X86::MUL_FST0r },
+  { X86::MUL_Fp64  , X86::MUL_FST0r },
+  { X86::MUL_Fp80  , X86::MUL_FST0r },
+  { X86::SUB_Fp32  , X86::SUB_FST0r },
+  { X86::SUB_Fp64  , X86::SUB_FST0r },
+  { X86::SUB_Fp80  , X86::SUB_FST0r },
+};
+
+// ReverseST0Table - Map: A = B op C  into: ST(0) = ST(i) op ST(0)
+static const TableEntry ReverseST0Table[] = {
+  { X86::ADD_Fp32  , X86::ADD_FST0r  },   // commutative
+  { X86::ADD_Fp64  , X86::ADD_FST0r  },   // commutative
+  { X86::ADD_Fp80  , X86::ADD_FST0r  },   // commutative
+  { X86::DIV_Fp32  , X86::DIVR_FST0r },
+  { X86::DIV_Fp64  , X86::DIVR_FST0r },
+  { X86::DIV_Fp80  , X86::DIVR_FST0r },
+  { X86::MUL_Fp32  , X86::MUL_FST0r  },   // commutative
+  { X86::MUL_Fp64  , X86::MUL_FST0r  },   // commutative
+  { X86::MUL_Fp80  , X86::MUL_FST0r  },   // commutative
+  { X86::SUB_Fp32  , X86::SUBR_FST0r },
+  { X86::SUB_Fp64  , X86::SUBR_FST0r },
+  { X86::SUB_Fp80  , X86::SUBR_FST0r },
+};
+
+// ForwardSTiTable - Map: A = B op C  into: ST(i) = ST(0) op ST(i)
+static const TableEntry ForwardSTiTable[] = {
+  { X86::ADD_Fp32  , X86::ADD_FrST0  },   // commutative
+  { X86::ADD_Fp64  , X86::ADD_FrST0  },   // commutative
+  { X86::ADD_Fp80  , X86::ADD_FrST0  },   // commutative
+  { X86::DIV_Fp32  , X86::DIVR_FrST0 },
+  { X86::DIV_Fp64  , X86::DIVR_FrST0 },
+  { X86::DIV_Fp80  , X86::DIVR_FrST0 },
+  { X86::MUL_Fp32  , X86::MUL_FrST0  },   // commutative
+  { X86::MUL_Fp64  , X86::MUL_FrST0  },   // commutative
+  { X86::MUL_Fp80  , X86::MUL_FrST0  },   // commutative
+  { X86::SUB_Fp32  , X86::SUBR_FrST0 },
+  { X86::SUB_Fp64  , X86::SUBR_FrST0 },
+  { X86::SUB_Fp80  , X86::SUBR_FrST0 },
+};
+
+// ReverseSTiTable - Map: A = B op C  into: ST(i) = ST(i) op ST(0)
+static const TableEntry ReverseSTiTable[] = {
+  { X86::ADD_Fp32  , X86::ADD_FrST0 },
+  { X86::ADD_Fp64  , X86::ADD_FrST0 },
+  { X86::ADD_Fp80  , X86::ADD_FrST0 },
+  { X86::DIV_Fp32  , X86::DIV_FrST0 },
+  { X86::DIV_Fp64  , X86::DIV_FrST0 },
+  { X86::DIV_Fp80  , X86::DIV_FrST0 },
+  { X86::MUL_Fp32  , X86::MUL_FrST0 },
+  { X86::MUL_Fp64  , X86::MUL_FrST0 },
+  { X86::MUL_Fp80  , X86::MUL_FrST0 },
+  { X86::SUB_Fp32  , X86::SUB_FrST0 },
+  { X86::SUB_Fp64  , X86::SUB_FrST0 },
+  { X86::SUB_Fp80  , X86::SUB_FrST0 },
+};
+
+
+/// handleTwoArgFP - Handle instructions like FADD and friends which are virtual
+/// instructions which need to be simplified and possibly transformed.
+///
+/// Result: ST(0) = fsub  ST(0), ST(i)
+///         ST(i) = fsub  ST(0), ST(i)
+///         ST(0) = fsubr ST(0), ST(i)
+///         ST(i) = fsubr ST(0), ST(i)
+///
+void FPS::handleTwoArgFP(MachineBasicBlock::iterator &I) {
+  ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table);
+  ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable);
+  MachineInstr *MI = I;
+
+  unsigned NumOperands = MI->getDesc().getNumOperands();
+  assert(NumOperands == 3 && "Illegal TwoArgFP instruction!");
+  unsigned Dest = getFPReg(MI->getOperand(0));
+  unsigned Op0 = getFPReg(MI->getOperand(NumOperands-2));
+  unsigned Op1 = getFPReg(MI->getOperand(NumOperands-1));
+  bool KillsOp0 = MI->killsRegister(X86::FP0+Op0);
+  bool KillsOp1 = MI->killsRegister(X86::FP0+Op1);
+  DebugLoc dl = MI->getDebugLoc();
+
+  unsigned TOS = getStackEntry(0);
+
+  // One of our operands must be on the top of the stack.  If neither is yet, we
+  // need to move one.
+  if (Op0 != TOS && Op1 != TOS) {   // No operand at TOS?
+    // We can choose to move either operand to the top of the stack.  If one of
+    // the operands is killed by this instruction, we want that one so that we
+    // can update right on top of the old version.
+    if (KillsOp0) {
+      moveToTop(Op0, I);         // Move dead operand to TOS.
+      TOS = Op0;
+    } else if (KillsOp1) {
+      moveToTop(Op1, I);
+      TOS = Op1;
+    } else {
+      // All of the operands are live after this instruction executes, so we
+      // cannot update on top of any operand.  Because of this, we must
+      // duplicate one of the stack elements to the top.  It doesn't matter
+      // which one we pick.
+      //
+      duplicateToTop(Op0, Dest, I);
+      Op0 = TOS = Dest;
+      KillsOp0 = true;
+    }
+  } else if (!KillsOp0 && !KillsOp1) {
+    // If we DO have one of our operands at the top of the stack, but we don't
+    // have a dead operand, we must duplicate one of the operands to a new slot
+    // on the stack.
+    duplicateToTop(Op0, Dest, I);
+    Op0 = TOS = Dest;
+    KillsOp0 = true;
+  }
+
+  // Now we know that one of our operands is on the top of the stack, and at
+  // least one of our operands is killed by this instruction.
+  assert((TOS == Op0 || TOS == Op1) && (KillsOp0 || KillsOp1) &&
+         "Stack conditions not set up right!");
+
+  // We decide which form to use based on what is on the top of the stack, and
+  // which operand is killed by this instruction.
+  const TableEntry *InstTable;
+  bool isForward = TOS == Op0;
+  bool updateST0 = (TOS == Op0 && !KillsOp1) || (TOS == Op1 && !KillsOp0);
+  if (updateST0) {
+    if (isForward)
+      InstTable = ForwardST0Table;
+    else
+      InstTable = ReverseST0Table;
+  } else {
+    if (isForward)
+      InstTable = ForwardSTiTable;
+    else
+      InstTable = ReverseSTiTable;
+  }
+
+  int Opcode = Lookup(InstTable, array_lengthof(ForwardST0Table),
+                      MI->getOpcode());
+  assert(Opcode != -1 && "Unknown TwoArgFP pseudo instruction!");
+
+  // NotTOS - The register which is not on the top of stack...
+  unsigned NotTOS = (TOS == Op0) ? Op1 : Op0;
+
+  // Replace the old instruction with a new instruction
+  MBB->remove(I++);
+  I = BuildMI(*MBB, I, dl, TII->get(Opcode)).addReg(getSTReg(NotTOS));
+
+  // If both operands are killed, pop one off of the stack in addition to
+  // overwriting the other one.
+  if (KillsOp0 && KillsOp1 && Op0 != Op1) {
+    assert(!updateST0 && "Should have updated other operand!");
+    popStackAfter(I);   // Pop the top of stack
+  }
+
+  // Update stack information so that we know the destination register is now on
+  // the stack.
+  unsigned UpdatedSlot = getSlot(updateST0 ? TOS : NotTOS);
+  assert(UpdatedSlot < StackTop && Dest < 7);
+  Stack[UpdatedSlot]   = Dest;
+  RegMap[Dest]         = UpdatedSlot;
+  MBB->getParent()->DeleteMachineInstr(MI); // Remove the old instruction
+}
+
+/// handleCompareFP - Handle FUCOM and FUCOMI instructions, which have two FP
+/// register arguments and no explicit destinations.
+///
+void FPS::handleCompareFP(MachineBasicBlock::iterator &I) {
+  ASSERT_SORTED(ForwardST0Table); ASSERT_SORTED(ReverseST0Table);
+  ASSERT_SORTED(ForwardSTiTable); ASSERT_SORTED(ReverseSTiTable);
+  MachineInstr *MI = I;
+
+  unsigned NumOperands = MI->getDesc().getNumOperands();
+  assert(NumOperands == 2 && "Illegal FUCOM* instruction!");
+  unsigned Op0 = getFPReg(MI->getOperand(NumOperands-2));
+  unsigned Op1 = getFPReg(MI->getOperand(NumOperands-1));
+  bool KillsOp0 = MI->killsRegister(X86::FP0+Op0);
+  bool KillsOp1 = MI->killsRegister(X86::FP0+Op1);
+
+  // Make sure the first operand is on the top of stack, the other one can be
+  // anywhere.
+  moveToTop(Op0, I);
+
+  // Change from the pseudo instruction to the concrete instruction.
+  MI->getOperand(0).setReg(getSTReg(Op1));
+  MI->RemoveOperand(1);
+  MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
+
+  // If any of the operands are killed by this instruction, free them.
+  if (KillsOp0) freeStackSlotAfter(I, Op0);
+  if (KillsOp1 && Op0 != Op1) freeStackSlotAfter(I, Op1);
+}
+
+/// handleCondMovFP - Handle two address conditional move instructions.  These
+/// instructions move a st(i) register to st(0) iff a condition is true.  These
+/// instructions require that the first operand is at the top of the stack, but
+/// otherwise don't modify the stack at all.
+void FPS::handleCondMovFP(MachineBasicBlock::iterator &I) {
+  MachineInstr *MI = I;
+
+  unsigned Op0 = getFPReg(MI->getOperand(0));
+  unsigned Op1 = getFPReg(MI->getOperand(2));
+  bool KillsOp1 = MI->killsRegister(X86::FP0+Op1);
+
+  // The first operand *must* be on the top of the stack.
+  moveToTop(Op0, I);
+
+  // Change the second operand to the stack register that the operand is in.
+  // Change from the pseudo instruction to the concrete instruction.
+  MI->RemoveOperand(0);
+  MI->RemoveOperand(1);
+  MI->getOperand(0).setReg(getSTReg(Op1));
+  MI->setDesc(TII->get(getConcreteOpcode(MI->getOpcode())));
+  
+  // If we kill the second operand, make sure to pop it from the stack.
+  if (Op0 != Op1 && KillsOp1) {
+    // Get this value off of the register stack.
+    freeStackSlotAfter(I, Op1);
+  }
+}
+
+
+/// handleSpecialFP - Handle special instructions which behave unlike other
+/// floating point instructions.  This is primarily intended for use by pseudo
+/// instructions.
+///
+void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
+  MachineInstr *MI = I;
+  DebugLoc dl = MI->getDebugLoc();
+  switch (MI->getOpcode()) {
+  default: llvm_unreachable("Unknown SpecialFP instruction!");
+  case X86::FpGET_ST0_32:// Appears immediately after a call returning FP type!
+  case X86::FpGET_ST0_64:// Appears immediately after a call returning FP type!
+  case X86::FpGET_ST0_80:// Appears immediately after a call returning FP type!
+    assert(StackTop == 0 && "Stack should be empty after a call!");
+    pushReg(getFPReg(MI->getOperand(0)));
+    break;
+  case X86::FpGET_ST1_32:// Appears immediately after a call returning FP type!
+  case X86::FpGET_ST1_64:// Appears immediately after a call returning FP type!
+  case X86::FpGET_ST1_80:{// Appears immediately after a call returning FP type!
+    // FpGET_ST1 should occur right after a FpGET_ST0 for a call or inline asm.
+    // The pattern we expect is:
+    //  CALL
+    //  FP1 = FpGET_ST0
+    //  FP4 = FpGET_ST1
+    //
+    // At this point, we've pushed FP1 on the top of stack, so it should be
+    // present if it isn't dead.  If it was dead, we already emitted a pop to
+    // remove it from the stack and StackTop = 0.
+    
+    // Push FP4 as top of stack next.
+    pushReg(getFPReg(MI->getOperand(0)));
+
+    // If StackTop was 0 before we pushed our operand, then ST(0) must have been
+    // dead.  In this case, the ST(1) value is the only thing that is live, so
+    // it should be on the TOS (after the pop that was emitted) and is.  Just
+    // continue in this case.
+    if (StackTop == 1)
+      break;
+    
+    // Because pushReg just pushed ST(1) as TOS, we now have to swap the two top
+    // elements so that our accounting is correct.
+    unsigned RegOnTop = getStackEntry(0);
+    unsigned RegNo = getStackEntry(1);
+    
+    // Swap the slots the regs are in.
+    std::swap(RegMap[RegNo], RegMap[RegOnTop]);
+    
+    // Swap stack slot contents.
+    assert(RegMap[RegOnTop] < StackTop);
+    std::swap(Stack[RegMap[RegOnTop]], Stack[StackTop-1]);
+    break;
+  }
+  case X86::FpSET_ST0_32:
+  case X86::FpSET_ST0_64:
+  case X86::FpSET_ST0_80: {
+    unsigned Op0 = getFPReg(MI->getOperand(0));
+
+    // FpSET_ST0_80 is generated by copyRegToReg for both function return
+    // and inline assembly with the "st" constrain. In the latter case,
+    // it is possible for ST(0) to be alive after this instruction.
+    if (!MI->killsRegister(X86::FP0 + Op0)) {
+      // Duplicate Op0
+      duplicateToTop(0, 7 /*temp register*/, I);
+    } else {
+      moveToTop(Op0, I);
+    }
+    --StackTop;   // "Forget" we have something on the top of stack!
+    break;
+  }
+  case X86::FpSET_ST1_32:
+  case X86::FpSET_ST1_64:
+  case X86::FpSET_ST1_80:
+    // StackTop can be 1 if a FpSET_ST0_* was before this. Exchange them.
+    if (StackTop == 1) {
+      BuildMI(*MBB, I, dl, TII->get(X86::XCH_F)).addReg(X86::ST1);
+      NumFXCH++;
+      StackTop = 0;
+      break;
+    }
+    assert(StackTop == 2 && "Stack should have two element on it to return!");
+    --StackTop;   // "Forget" we have something on the top of stack!
+    break;
+  case X86::MOV_Fp3232:
+  case X86::MOV_Fp3264:
+  case X86::MOV_Fp6432:
+  case X86::MOV_Fp6464: 
+  case X86::MOV_Fp3280:
+  case X86::MOV_Fp6480:
+  case X86::MOV_Fp8032:
+  case X86::MOV_Fp8064: 
+  case X86::MOV_Fp8080: {
+    const MachineOperand &MO1 = MI->getOperand(1);
+    unsigned SrcReg = getFPReg(MO1);
+
+    const MachineOperand &MO0 = MI->getOperand(0);
+    // These can be created due to inline asm. Two address pass can introduce
+    // copies from RFP registers to virtual registers.
+    if (MO0.getReg() == X86::ST0 && SrcReg == 0) {
+      assert(MO1.isKill());
+      // Treat %ST0<def> = MOV_Fp8080 %FP0<kill>
+      // like  FpSET_ST0_80 %FP0<kill>, %ST0<imp-def>
+      assert((StackTop == 1 || StackTop == 2)
+             && "Stack should have one or two element on it to return!");
+      --StackTop;   // "Forget" we have something on the top of stack!
+      break;
+    } else if (MO0.getReg() == X86::ST1 && SrcReg == 1) {
+      assert(MO1.isKill());
+      // Treat %ST1<def> = MOV_Fp8080 %FP1<kill>
+      // like  FpSET_ST1_80 %FP0<kill>, %ST1<imp-def>
+      // StackTop can be 1 if a FpSET_ST0_* was before this. Exchange them.
+      if (StackTop == 1) {
+        BuildMI(*MBB, I, dl, TII->get(X86::XCH_F)).addReg(X86::ST1);
+        NumFXCH++;
+        StackTop = 0;
+        break;
+      }
+      assert(StackTop == 2 && "Stack should have two element on it to return!");
+      --StackTop;   // "Forget" we have something on the top of stack!
+      break;
+    }
+
+    unsigned DestReg = getFPReg(MO0);
+    if (MI->killsRegister(X86::FP0+SrcReg)) {
+      // If the input operand is killed, we can just change the owner of the
+      // incoming stack slot into the result.
+      unsigned Slot = getSlot(SrcReg);
+      assert(Slot < 7 && DestReg < 7 && "FpMOV operands invalid!");
+      Stack[Slot] = DestReg;
+      RegMap[DestReg] = Slot;
+
+    } else {
+      // For FMOV we just duplicate the specified value to a new stack slot.
+      // This could be made better, but would require substantial changes.
+      duplicateToTop(SrcReg, DestReg, I);
+    }
+    }
+    break;
+  case TargetOpcode::INLINEASM: {
+    // The inline asm MachineInstr currently only *uses* FP registers for the
+    // 'f' constraint.  These should be turned into the current ST(x) register
+    // in the machine instr.  Also, any kills should be explicitly popped after
+    // the inline asm.
+    unsigned Kills[7];
+    unsigned NumKills = 0;
+    for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+      MachineOperand &Op = MI->getOperand(i);
+      if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
+        continue;
+      assert(Op.isUse() && "Only handle inline asm uses right now");
+      
+      unsigned FPReg = getFPReg(Op);
+      Op.setReg(getSTReg(FPReg));
+      
+      // If we kill this operand, make sure to pop it from the stack after the
+      // asm.  We just remember it for now, and pop them all off at the end in
+      // a batch.
+      if (Op.isKill())
+        Kills[NumKills++] = FPReg;
+    }
+
+    // If this asm kills any FP registers (is the last use of them) we must
+    // explicitly emit pop instructions for them.  Do this now after the asm has
+    // executed so that the ST(x) numbers are not off (which would happen if we
+    // did this inline with operand rewriting).
+    //
+    // Note: this might be a non-optimal pop sequence.  We might be able to do
+    // better by trying to pop in stack order or something.
+    MachineBasicBlock::iterator InsertPt = MI;
+    while (NumKills)
+      freeStackSlotAfter(InsertPt, Kills[--NumKills]);
+
+    // Don't delete the inline asm!
+    return;
+  }
+      
+  case X86::RET:
+  case X86::RETI:
+    // If RET has an FP register use operand, pass the first one in ST(0) and
+    // the second one in ST(1).
+    if (isStackEmpty()) return;  // Quick check to see if any are possible.
+    
+    // Find the register operands.
+    unsigned FirstFPRegOp = ~0U, SecondFPRegOp = ~0U;
+    
+    for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
+      MachineOperand &Op = MI->getOperand(i);
+      if (!Op.isReg() || Op.getReg() < X86::FP0 || Op.getReg() > X86::FP6)
+        continue;
+      // FP Register uses must be kills unless there are two uses of the same
+      // register, in which case only one will be a kill.
+      assert(Op.isUse() &&
+             (Op.isKill() ||                        // Marked kill.
+              getFPReg(Op) == FirstFPRegOp ||       // Second instance.
+              MI->killsRegister(Op.getReg())) &&    // Later use is marked kill.
+             "Ret only defs operands, and values aren't live beyond it");
+
+      if (FirstFPRegOp == ~0U)
+        FirstFPRegOp = getFPReg(Op);
+      else {
+        assert(SecondFPRegOp == ~0U && "More than two fp operands!");
+        SecondFPRegOp = getFPReg(Op);
+      }
+
+      // Remove the operand so that later passes don't see it.
+      MI->RemoveOperand(i);
+      --i, --e;
+    }
+    
+    // There are only four possibilities here:
+    // 1) we are returning a single FP value.  In this case, it has to be in
+    //    ST(0) already, so just declare success by removing the value from the
+    //    FP Stack.
+    if (SecondFPRegOp == ~0U) {
+      // Assert that the top of stack contains the right FP register.
+      assert(StackTop == 1 && FirstFPRegOp == getStackEntry(0) &&
+             "Top of stack not the right register for RET!");
+      
+      // Ok, everything is good, mark the value as not being on the stack
+      // anymore so that our assertion about the stack being empty at end of
+      // block doesn't fire.
+      StackTop = 0;
+      return;
+    }
+    
+    // Otherwise, we are returning two values:
+    // 2) If returning the same value for both, we only have one thing in the FP
+    //    stack.  Consider:  RET FP1, FP1
+    if (StackTop == 1) {
+      assert(FirstFPRegOp == SecondFPRegOp && FirstFPRegOp == getStackEntry(0)&&
+             "Stack misconfiguration for RET!");
+      
+      // Duplicate the TOS so that we return it twice.  Just pick some other FPx
+      // register to hold it.
+      unsigned NewReg = (FirstFPRegOp+1)%7;
+      duplicateToTop(FirstFPRegOp, NewReg, MI);
+      FirstFPRegOp = NewReg;
+    }
+    
+    /// Okay we know we have two different FPx operands now:
+    assert(StackTop == 2 && "Must have two values live!");
+    
+    /// 3) If SecondFPRegOp is currently in ST(0) and FirstFPRegOp is currently
+    ///    in ST(1).  In this case, emit an fxch.
+    if (getStackEntry(0) == SecondFPRegOp) {
+      assert(getStackEntry(1) == FirstFPRegOp && "Unknown regs live");
+      moveToTop(FirstFPRegOp, MI);
+    }
+    
+    /// 4) Finally, FirstFPRegOp must be in ST(0) and SecondFPRegOp must be in
+    /// ST(1).  Just remove both from our understanding of the stack and return.
+    assert(getStackEntry(0) == FirstFPRegOp && "Unknown regs live");
+    assert(getStackEntry(1) == SecondFPRegOp && "Unknown regs live");
+    StackTop = 0;
+    return;
+  }
+
+  I = MBB->erase(I);  // Remove the pseudo instruction
+  --I;
+}