Add Om1 lowering with no optimizations

src/IceTargetLoweringX8632.cpp

Index: src/IceTargetLoweringX8632.cpp
diff --git a/src/IceTargetLoweringX8632.cpp b/src/IceTargetLoweringX8632.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..cca4c1fdeb0672d89e1cd7d6160ecf980278c38f
--- /dev/null
+++ b/src/IceTargetLoweringX8632.cpp
@@ -0,0 +1,1869 @@
+//===- subzero/src/IceTargetLoweringX8632.cpp - x86-32 lowering -----------===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements the TargetLoweringX8632 class, which
+// consists almost entirely of the lowering sequence for each
+// high-level instruction.  It also implements
+// TargetX8632Fast::postLower() which does the simplest possible
+// register allocation for the "fast" target.
+//
+//===----------------------------------------------------------------------===//
+
+#include "IceDefs.h"
+#include "IceCfg.h"
+#include "IceCfgNode.h"
+#include "IceInstX8632.h"
+#include "IceOperand.h"
+#include "IceTargetLoweringX8632.def"
+#include "IceTargetLoweringX8632.h"
+
+namespace Ice {
+
+namespace {
+
+// The following table summarizes the logic for lowering the fcmp instruction.
+// There is one table entry for each of the 16 conditions.  A comment in
+// lowerFcmp() describes the lowering template.  In the most general case, there
+// is a compare followed by two conditional branches, because some fcmp
+// conditions don't map to a single x86 conditional branch.  However, in many
+// cases it is possible to swap the operands in the comparison and have a single
+// conditional branch.  Since it's quite tedious to validate the table by hand,
+// good execution tests are helpful.
+
+const struct _TableFcmp {
+  uint32_t Default;
+  bool SwapOperands;
+  InstX8632Br::BrCond C1, C2;
+} TableFcmp[] = {
+#define X(val, dflt, swap, C1, C2)                                             \
+  { dflt, swap, InstX8632Br::C1, InstX8632Br::C2 }                      \
+  ,
+    FCMPX8632_TABLE
+#undef X
+  };
+const size_t TableFcmpSize = llvm::array_lengthof(TableFcmp);
+
+// The following table summarizes the logic for lowering the icmp instruction
+// for i32 and narrower types.  Each icmp condition has a clear mapping to an
+// x86 conditional branch instruction.
+
+const struct _TableIcmp32 {
+  InstX8632Br::BrCond Mapping;
+} TableIcmp32[] = {
+#define X(val, C_32, C1_64, C2_64, C3_64)                                      \
+  { InstX8632Br::C_32 }                                                 \
+  ,
+    ICMPX8632_TABLE
+#undef X
+  };
+const size_t TableIcmp32Size = llvm::array_lengthof(TableIcmp32);
+
+// The following table summarizes the logic for lowering the icmp instruction
+// for the i64 type.  For Eq and Ne, two separate 32-bit comparisons and
+// conditional branches are needed.  For the other conditions, three separate
+// conditional branches are needed.
+const struct _TableIcmp64 {
+  InstX8632Br::BrCond C1, C2, C3;
+} TableIcmp64[] = {
+#define X(val, C_32, C1_64, C2_64, C3_64)                                       \
+  { InstX8632Br::C1_64, InstX8632Br::C2_64, InstX8632Br::C3_64 } \
+  ,
+    ICMPX8632_TABLE
+#undef X
+  };
+const size_t TableIcmp64Size = llvm::array_lengthof(TableIcmp64);
+
+InstX8632Br::BrCond getIcmp32Mapping(InstIcmp::ICond Cond) {
+  size_t Index = static_cast<size_t>(Cond);
+  assert(Index < TableIcmp32Size);
+  return TableIcmp32[Index].Mapping;
+}
+
+// In some cases, there are x-macros tables for both high-level and
+// low-level instructions/operands that use the same enum key value.
+// The tables are kept separate to maintain a proper separation
+// between abstraction layers.  There is a risk that the tables
+// could get out of sync if enum values are reordered or if entries
+// are added or deleted.  This dummy function uses static_assert to
+// ensure everything is kept in sync.
+void xMacroIntegrityCheck() {
+  // Validate the enum values in FCMPX8632_TABLE.
+  {
+    // Define a temporary set of enum values based on low-level
+    // table entries.
+    enum _tmp_enum {
+#define X(val, dflt, swap, C1, C2) _tmp_##val,
+      FCMPX8632_TABLE
+#undef X
+    };
+// Define a set of constants based on high-level table entries.
+#define X(tag, str) static const int _table1_##tag = InstFcmp::tag;
+    ICEINSTFCMP_TABLE;
+#undef X
+// Define a set of constants based on low-level table entries,
+// and ensure the table entry keys are consistent.
+#define X(val, dflt, swap, C1, C2)                                             \
+  static const int _table2_##val = _tmp_##val;                                 \
+  STATIC_ASSERT(_table1_##val == _table2_##val);
+    FCMPX8632_TABLE;
+#undef X
+// Repeat the static asserts with respect to the high-level
+// table entries in case the high-level table has extra entries.
+#define X(tag, str) STATIC_ASSERT(_table1_##tag == _table2_##tag);
+    ICEINSTFCMP_TABLE;
+#undef X
+  }
+
+  // Validate the enum values in ICMPX8632_TABLE.
+  {
+    // Define a temporary set of enum values based on low-level
+    // table entries.
+    enum _tmp_enum {
+#define X(val, C_32, C1_64, C2_64, C3_64) _tmp_##val,
+      ICMPX8632_TABLE
+#undef X
+    };
+// Define a set of constants based on high-level table entries.
+#define X(tag, str) static const int _table1_##tag = InstIcmp::tag;
+    ICEINSTICMP_TABLE;
+#undef X
+// Define a set of constants based on low-level table entries,
+// and ensure the table entry keys are consistent.
+#define X(val, C_32, C1_64, C2_64, C3_64)                                      \
+  static const int _table2_##val = _tmp_##val;                                 \
+  STATIC_ASSERT(_table1_##val == _table2_##val);
+    ICMPX8632_TABLE;
+#undef X
+// Repeat the static asserts with respect to the high-level
+// table entries in case the high-level table has extra entries.
+#define X(tag, str) STATIC_ASSERT(_table1_##tag == _table2_##tag);
+    ICEINSTICMP_TABLE;
+#undef X
+  }
+
+  // Validate the enum values in ICETYPEX8632_TABLE.
+  {
+    // Define a temporary set of enum values based on low-level
+    // table entries.
+    enum _tmp_enum {
+#define X(tag, cvt, sdss, width) _tmp_##tag,
+      ICETYPEX8632_TABLE
+#undef X
+    };
+// Define a set of constants based on high-level table entries.
+#define X(tag, size, align, str) static const int _table1_##tag = tag;
+    ICETYPE_TABLE;
+#undef X
+// Define a set of constants based on low-level table entries,
+// and ensure the table entry keys are consistent.
+#define X(tag, cvt, sdss, width)                                      \
+  static const int _table2_##tag = _tmp_##tag;                                 \
+  STATIC_ASSERT(_table1_##tag == _table2_##tag);
+    ICETYPEX8632_TABLE;
+#undef X
+// Repeat the static asserts with respect to the high-level
+// table entries in case the high-level table has extra entries.
+#define X(tag, size, align, str) STATIC_ASSERT(_table1_##tag == _table2_##tag);
+    ICETYPE_TABLE;
+#undef X
+  }
+}
+
+} // end of anonymous namespace
+
+TargetX8632::TargetX8632(Cfg *Func)
+    : TargetLowering(Func), IsEbpBasedFrame(false), FrameSizeLocals(0),
+      LocalsSizeBytes(0), NextLabelNumber(0), ComputedLiveRanges(false),
+      PhysicalRegisters(VarList(Reg_NUM)) {
+  llvm::SmallBitVector IntegerRegisters(Reg_NUM);
+  llvm::SmallBitVector IntegerRegistersI8(Reg_NUM);
+  llvm::SmallBitVector FloatRegisters(Reg_NUM);
+  llvm::SmallBitVector InvalidRegisters(Reg_NUM);
+  ScratchRegs.resize(Reg_NUM);
+#define X(val, init, name, name16, name8, scratch, preserved, stackptr,        \
+          frameptr, isI8, isInt, isFP)                                         \
+  IntegerRegisters[val] = isInt;                                               \
+  IntegerRegistersI8[val] = isI8;                                              \
+  FloatRegisters[val] = isFP;                                                  \
+  ScratchRegs[val] = scratch;
+  REGX8632_TABLE;
+#undef X
+  TypeToRegisterSet[IceType_void] = InvalidRegisters;
+  TypeToRegisterSet[IceType_i1] = IntegerRegistersI8;
+  TypeToRegisterSet[IceType_i8] = IntegerRegistersI8;
+  TypeToRegisterSet[IceType_i16] = IntegerRegisters;
+  TypeToRegisterSet[IceType_i32] = IntegerRegisters;
+  TypeToRegisterSet[IceType_i64] = IntegerRegisters;
+  TypeToRegisterSet[IceType_f32] = FloatRegisters;
+  TypeToRegisterSet[IceType_f64] = FloatRegisters;
+}
+
+void TargetX8632::translateOm1() {
+  GlobalContext *Context = Func->getContext();
+  Ostream &Str = Context->getStrDump();
+  Timer T_placePhiLoads;
+  Func->placePhiLoads();
+  if (Func->hasError())
+    return;
+  T_placePhiLoads.printElapsedUs(Context, "placePhiLoads()");
+  Timer T_placePhiStores;
+  Func->placePhiStores();
+  if (Func->hasError())
+    return;
+  T_placePhiStores.printElapsedUs(Context, "placePhiStores()");
+  Timer T_deletePhis;
+  Func->deletePhis();
+  if (Func->hasError())
+    return;
+  T_deletePhis.printElapsedUs(Context, "deletePhis()");
+  if (Context->isVerbose())
+    Str << "================ After Phi lowering ================\n";
+  Func->dump();
+
+  Timer T_genCode;
+  Func->genCode();
+  if (Func->hasError())
+    return;
+  T_genCode.printElapsedUs(Context, "genCode()");
+  if (Context->isVerbose())
+    Str << "================ After initial x8632 codegen ================\n";
+  Func->dump();
+
+  Timer T_genFrame;
+  Func->genFrame();
+  if (Func->hasError())
+    return;
+  T_genFrame.printElapsedUs(Context, "genFrame()");
+  if (Context->isVerbose())
+    Str << "================ After stack frame mapping ================\n";
+  Func->dump();
+}
+
+IceString TargetX8632::RegNames[] = {
+#define X(val, init, name, name16, name8, scratch, preserved, stackptr,        \
+          frameptr, isI8, isInt, isFP)                                         \
+  name,
+  REGX8632_TABLE
+#undef X
+};
+
+Variable *TargetX8632::getPhysicalRegister(SizeT RegNum) {
+  assert(RegNum < PhysicalRegisters.size());
+  Variable *Reg = PhysicalRegisters[RegNum];
+  if (Reg == NULL) {
+    CfgNode *Node = NULL; // NULL means multi-block lifetime
+    Reg = Func->makeVariable(IceType_i32, Node);
+    Reg->setRegNum(RegNum);
+    PhysicalRegisters[RegNum] = Reg;
+  }
+  return Reg;
+}
+
+IceString TargetX8632::getRegName(SizeT RegNum, Type Ty) const {
+  assert(RegNum < Reg_NUM);
+  static IceString RegNames8[] = {
+#define X(val, init, name, name16, name8, scratch, preserved, stackptr,        \
+          frameptr, isI8, isInt, isFP)                                         \
+  "" name8,
+    REGX8632_TABLE
+#undef X
+  };
+  static IceString RegNames16[] = {
+#define X(val, init, name, name16, name8, scratch, preserved, stackptr,        \
+          frameptr, isI8, isInt, isFP)                                         \
+  "" name16,
+    REGX8632_TABLE
+#undef X
+  };
+  switch (Ty) {
+  case IceType_i1:
+  case IceType_i8:
+    return RegNames8[RegNum];
+  case IceType_i16:
+    return RegNames16[RegNum];
+  default:
+    return RegNames[RegNum];
+  }
+}
+
+void TargetX8632::emitVariable(const Variable *Var,
+                               const Cfg *Func) const {
+  Ostream &Str = Ctx->getStrEmit();
+  assert(Var->getLocalUseNode() == NULL || Var->getLocalUseNode() == Func->getCurrentNode());
+  if (Var->hasReg()) {
+    Str << getRegName(Var->getRegNum(), Var->getType());
+    return;
+  }
+  Str << InstX8632::getWidthString(Var->getType());
+  Str << " [" << getRegName(
+                         getFrameOrStackReg(), IceType_i32);
+  int32_t Offset = Var->getStackOffset() + getStackAdjustment();
+  if (Offset) {
+    if (Offset > 0)
+      Str << "+";
+    Str << Offset;
+  }
+  Str << "]";
+}
+
+// Helper function for addProlog().  Sets the frame offset for Arg,
+// updates InArgsSizeBytes according to Arg's width, and generates an
+// instruction to copy Arg into its assigned register if applicable.
+// For an I64 arg that has been split into Lo and Hi components, it
+// calls itself recursively on the components, taking care to handle
+// Lo first because of the little-endian architecture.
+void TargetX8632::setArgOffsetAndCopy(Variable *Arg, Variable *FramePtr,
+                                      int32_t BasicFrameOffset,
+                                      int32_t &InArgsSizeBytes) {
+  Variable *Lo = Arg->getLo();
+  Variable *Hi = Arg->getHi();
+  Type Ty = Arg->getType();
+  if (Lo && Hi && Ty == IceType_i64) {
+    assert(Lo->getType() != IceType_i64); // don't want infinite recursion
+    assert(Hi->getType() != IceType_i64); // don't want infinite recursion
+    setArgOffsetAndCopy(Lo, FramePtr, BasicFrameOffset, InArgsSizeBytes);
+    setArgOffsetAndCopy(Hi, FramePtr, BasicFrameOffset, InArgsSizeBytes);
+    return;
+  }
+  Arg->setStackOffset(BasicFrameOffset + InArgsSizeBytes);
+  if (Arg->hasReg()) {
+    assert(Ty != IceType_i64);
+    OperandX8632Mem *Mem = OperandX8632Mem::create(
+        Func, Ty, FramePtr,
+        Ctx->getConstantInt(IceType_i32, Arg->getStackOffset()));
+    _mov(Arg, Mem);
+  }
+  InArgsSizeBytes += typeWidthInBytesOnStack(Ty);
+}
+
+void TargetX8632::addProlog(CfgNode *Node) {
+  // If SimpleCoalescing is false, each variable without a register
+  // gets its own unique stack slot, which leads to large stack
+  // frames.  If SimpleCoalescing is true, then each "global" variable
+  // without a register gets its own slot, but "local" variable slots
+  // are reused across basic blocks.  E.g., if A and B are local to
+  // block 1 and C is local to block 2, then C may share a slot with A
+  // or B.
+  const bool SimpleCoalescing = true;
+  int32_t InArgsSizeBytes = 0;
+  int32_t RetIpSizeBytes = 4;
+  int32_t PreservedRegsSizeBytes = 0;
+  LocalsSizeBytes = 0;
+  Context.init(Node);
+  Context.setInsertPoint(Context.getCur());
+
+  // Determine stack frame offsets for each Variable without a
+  // register assignment.  This can be done as one variable per stack
+  // slot.  Or, do coalescing by running the register allocator again
+  // with an infinite set of registers (as a side effect, this gives
+  // variables a second chance at physical register assignment).
+  //
+  // A middle ground approach is to leverage sparsity and allocate one
+  // block of space on the frame for globals (variables with
+  // multi-block lifetime), and one block to share for locals
+  // (single-block lifetime).
+
+  llvm::SmallBitVector CalleeSaves =
+      getRegisterSet(RegSet_CalleeSave, RegSet_None);
+
+  int32_t GlobalsSize = 0;
+  std::vector<int> LocalsSize(Func->getNumNodes());
+
+  // Prepass.  Compute RegsUsed, PreservedRegsSizeBytes, and
+  // LocalsSizeBytes.
+  RegsUsed = llvm::SmallBitVector(CalleeSaves.size());
+  const VarList &Variables = Func->getVariables();
+  const VarList &Args = Func->getArgs();
+  for (VarList::const_iterator I = Variables.begin(), E = Variables.end();
+       I != E; ++I) {
+    Variable *Var = *I;
+    if (Var->hasReg()) {
+      RegsUsed[Var->getRegNum()] = true;
+      continue;
+    }
+    // An argument passed on the stack already has a stack slot.
+    if (Var->getIsArg())
+      continue;
+    // A spill slot linked to a variable with a stack slot should reuse
+    // that stack slot.
+    if (Var->getWeight() == RegWeight::Zero && Var->getRegisterOverlap()) {
+      if (Variable *Linked = Var->getPreferredRegister()) {
+        if (!Linked->hasReg())
+          continue;
+      }
+    }
+    int32_t Increment = typeWidthInBytesOnStack(Var->getType());
+    if (SimpleCoalescing) {
+      if (Var->isMultiblockLife()) {
+        GlobalsSize += Increment;
+      } else {
+        SizeT NodeIndex = Var->getLocalUseNode()->getIndex();
+        LocalsSize[NodeIndex] += Increment;
+        if (LocalsSize[NodeIndex] > LocalsSizeBytes)
+          LocalsSizeBytes = LocalsSize[NodeIndex];
+      }
+    } else {
+      LocalsSizeBytes += Increment;
+    }
+  }
+  LocalsSizeBytes += GlobalsSize;
+
+  // Add push instructions for preserved registers.
+  for (SizeT i = 0; i < CalleeSaves.size(); ++i) {
+    if (CalleeSaves[i] && RegsUsed[i]) {
+      PreservedRegsSizeBytes += 4;
+      const bool SuppressStackAdjustment = true;
+      _push(getPhysicalRegister(i), SuppressStackAdjustment);
+    }
+  }
+
+  // Generate "push ebp; mov ebp, esp"
+  if (IsEbpBasedFrame) {
+    assert((RegsUsed & getRegisterSet(RegSet_FramePointer, RegSet_None))
+               .count() == 0);
+    PreservedRegsSizeBytes += 4;
+    Variable *ebp = getPhysicalRegister(Reg_ebp);
+    Variable *esp = getPhysicalRegister(Reg_esp);
+    const bool SuppressStackAdjustment = true;
+    _push(ebp, SuppressStackAdjustment);
+    _mov(ebp, esp);
+  }
+
+  // Generate "sub esp, LocalsSizeBytes"
+  if (LocalsSizeBytes)
+    _sub(getPhysicalRegister(Reg_esp),
+         Ctx->getConstantInt(IceType_i32, LocalsSizeBytes));
+
+  resetStackAdjustment();
+
+  // Fill in stack offsets for args, and copy args into registers for
+  // those that were register-allocated.  Args are pushed right to
+  // left, so Arg[0] is closest to the stack/frame pointer.
+  //
+  // TODO: Make this right for different width args, calling
+  // conventions, etc.  For one thing, args passed in registers will
+  // need to be copied/shuffled to their home registers (the
+  // RegManager code may have some permutation logic to leverage),
+  // and if they have no home register, home space will need to be
+  // allocated on the stack to copy into.
+  Variable *FramePtr = getPhysicalRegister(getFrameOrStackReg());
+  int32_t BasicFrameOffset = PreservedRegsSizeBytes + RetIpSizeBytes;
+  if (!IsEbpBasedFrame)
+    BasicFrameOffset += LocalsSizeBytes;
+  for (SizeT i = 0; i < Args.size(); ++i) {
+    Variable *Arg = Args[i];
+    setArgOffsetAndCopy(Arg, FramePtr, BasicFrameOffset, InArgsSizeBytes);
+  }
+
+  // Fill in stack offsets for locals.
+  int32_t TotalGlobalsSize = GlobalsSize;
+  GlobalsSize = 0;
+  LocalsSize.assign(LocalsSize.size(), 0);
+  int32_t NextStackOffset = 0;
+  for (VarList::const_iterator I = Variables.begin(), E = Variables.end();
+       I != E; ++I) {
+    Variable *Var = *I;
+    if (Var->hasReg()) {
+      RegsUsed[Var->getRegNum()] = true;
+      continue;
+    }
+    if (Var->getIsArg())
+      continue;
+    if (Var->getWeight() == RegWeight::Zero && Var->getRegisterOverlap()) {
+      if (Variable *Linked = Var->getPreferredRegister()) {
+        if (!Linked->hasReg()) {
+          // TODO: Make sure Linked has already been assigned a stack
+          // slot.
+          Var->setStackOffset(Linked->getStackOffset());
+          continue;
+        }
+      }
+    }
+    int32_t Increment = typeWidthInBytesOnStack(Var->getType());
+    if (SimpleCoalescing) {
+      if (Var->isMultiblockLife()) {
+        GlobalsSize += Increment;
+        NextStackOffset = GlobalsSize;
+      } else {
+        SizeT NodeIndex = Var->getLocalUseNode()->getIndex();
+        LocalsSize[NodeIndex] += Increment;
+        NextStackOffset = TotalGlobalsSize + LocalsSize[NodeIndex];
+      }
+    } else {
+      NextStackOffset += Increment;
+    }
+    if (IsEbpBasedFrame)
+      Var->setStackOffset(-NextStackOffset);
+    else
+      Var->setStackOffset(LocalsSizeBytes - NextStackOffset);
+  }
+  this->FrameSizeLocals = NextStackOffset;
+  this->HasComputedFrame = true;
+
+  if (Func->getContext()->isVerbose(IceV_Frame)) {
+    Func->getContext()->getStrDump() << "LocalsSizeBytes=" << LocalsSizeBytes
+                                     << "\n"
+                                     << "InArgsSizeBytes=" << InArgsSizeBytes
+                                     << "\n"
+                                     << "PreservedRegsSizeBytes="
+                                     << PreservedRegsSizeBytes << "\n";
+  }
+}
+
+void TargetX8632::addEpilog(CfgNode *Node) {
+  InstList &Insts = Node->getInsts();
+  InstList::reverse_iterator RI, E;
+  for (RI = Insts.rbegin(), E = Insts.rend(); RI != E; ++RI) {
+    if (llvm::isa<InstX8632Ret>(*RI))
+      break;
+  }
+  if (RI == E)
+    return;
+
+  // Convert the reverse_iterator position into its corresponding
+  // (forward) iterator position.
+  InstList::iterator InsertPoint = RI.base();
+  --InsertPoint;
+  Context.init(Node);
+  Context.setInsertPoint(InsertPoint);
+
+  Variable *esp = getPhysicalRegister(Reg_esp);
+  if (IsEbpBasedFrame) {
+    Variable *ebp = getPhysicalRegister(Reg_ebp);
+    _mov(esp, ebp);
+    _pop(ebp);
+  } else {
+    // add esp, LocalsSizeBytes
+    if (LocalsSizeBytes)
+      _add(esp, Ctx->getConstantInt(IceType_i32, LocalsSizeBytes));
+  }
+
+  // Add pop instructions for preserved registers.
+  llvm::SmallBitVector CalleeSaves =
+      getRegisterSet(RegSet_CalleeSave, RegSet_None);
+  for (SizeT i = 0; i < CalleeSaves.size(); ++i) {
+    SizeT j = CalleeSaves.size() - i - 1;
+    if (j == Reg_ebp && IsEbpBasedFrame)
+      continue;
+    if (CalleeSaves[j] && RegsUsed[j]) {
+      _pop(getPhysicalRegister(j));
+    }
+  }
+}
+
+void TargetX8632::split64(Variable *Var) {
+  switch (Var->getType()) {
+  default:
+    return;
+  case IceType_i64:
+  // TODO: Only consider F64 if we need to push each half when
+  // passing as an argument to a function call.  Note that each half
+  // is still typed as I32.
+  case IceType_f64:
+    break;
+  }
+  Variable *Lo = Var->getLo();
+  Variable *Hi = Var->getHi();
+  if (Lo) {
+    assert(Hi);
+    return;
+  }
+  assert(Hi == NULL);
+  Lo = Func->makeVariable(IceType_i32, Context.getNode(),
+                          Var->getName() + "__lo");
+  Hi = Func->makeVariable(IceType_i32, Context.getNode(),
+                          Var->getName() + "__hi");
+  Var->setLoHi(Lo, Hi);
+  if (Var->getIsArg()) {
+    Lo->setIsArg(Func);
+    Hi->setIsArg(Func);
+  }
+}
+
+Operand *TargetX8632::loOperand(Operand *Operand) {
+  assert(Operand->getType() == IceType_i64);
+  if (Operand->getType() != IceType_i64)
+    return Operand;
+  if (Variable *Var = llvm::dyn_cast<Variable>(Operand)) {
+    split64(Var);
+    return Var->getLo();
+  }
+  if (ConstantInteger *Const = llvm::dyn_cast<ConstantInteger>(Operand)) {
+    uint64_t Mask = (1ull << 32) - 1;
+    return Ctx->getConstantInt(IceType_i32, Const->getValue() & Mask);
+  }
+  if (OperandX8632Mem *Mem = llvm::dyn_cast<OperandX8632Mem>(Operand)) {
+    return OperandX8632Mem::create(Func, IceType_i32, Mem->getBase(),
+                                   Mem->getOffset(), Mem->getIndex(),
+                                   Mem->getShift());
+  }
+  llvm_unreachable("Unsupported operand type");
+  return NULL;
+}
+
+Operand *TargetX8632::hiOperand(Operand *Operand) {
+  assert(Operand->getType() == IceType_i64);
+  if (Operand->getType() != IceType_i64)
+    return Operand;
+  if (Variable *Var = llvm::dyn_cast<Variable>(Operand)) {
+    split64(Var);
+    return Var->getHi();
+  }
+  if (ConstantInteger *Const = llvm::dyn_cast<ConstantInteger>(Operand)) {
+    return Ctx->getConstantInt(IceType_i32, Const->getValue() >> 32);
+  }
+  if (OperandX8632Mem *Mem = llvm::dyn_cast<OperandX8632Mem>(Operand)) {
+    Constant *Offset = Mem->getOffset();
+    if (Offset == NULL)
+      Offset = Ctx->getConstantInt(IceType_i32, 4);
+    else if (ConstantInteger *IntOffset =
+                 llvm::dyn_cast<ConstantInteger>(Offset)) {
+      Offset = Ctx->getConstantInt(IceType_i32, 4 + IntOffset->getValue());
+    } else if (ConstantRelocatable *SymOffset =
+                   llvm::dyn_cast<ConstantRelocatable>(Offset)) {
+      Offset = Ctx->getConstantSym(IceType_i32, 4 + SymOffset->getOffset(),
+                                   SymOffset->getName());
+    }
+    return OperandX8632Mem::create(Func, IceType_i32, Mem->getBase(), Offset,
+                                   Mem->getIndex(), Mem->getShift());
+  }
+  llvm_unreachable("Unsupported operand type");
+  return NULL;
+}
+
+llvm::SmallBitVector TargetX8632::getRegisterSet(RegSetMask Include,
+                                                 RegSetMask Exclude) const {
+  llvm::SmallBitVector Registers(Reg_NUM);
+
+#define X(val, init, name, name16, name8, scratch, preserved, stackptr,        \
+          frameptr, isI8, isInt, isFP)                                         \
+  if (scratch && (Include & RegSet_CallerSave))                                \
+    Registers[val] = true;                                                     \
+  if (preserved && (Include & RegSet_CalleeSave))                              \
+    Registers[val] = true;                                                     \
+  if (stackptr && (Include & RegSet_StackPointer))                             \
+    Registers[val] = true;                                                     \
+  if (frameptr && (Include & RegSet_FramePointer))                             \
+    Registers[val] = true;                                                     \
+  if (scratch && (Exclude & RegSet_CallerSave))                                \
+    Registers[val] = false;                                                    \
+  if (preserved && (Exclude & RegSet_CalleeSave))                              \
+    Registers[val] = false;                                                    \
+  if (stackptr && (Exclude & RegSet_StackPointer))                             \
+    Registers[val] = false;                                                    \
+  if (frameptr && (Exclude & RegSet_FramePointer))                             \
+    Registers[val] = false;
+
+  REGX8632_TABLE
+
+#undef X
+
+  return Registers;
+}
+
+void TargetX8632::lowerAlloca(const InstAlloca *Inst) {
+  IsEbpBasedFrame = true;
+  // TODO(sehr,stichnot): align allocated memory, keep stack aligned, minimize
+  // the number of adjustments of esp, etc.
+  Variable *esp = getPhysicalRegister(Reg_esp);
+  Operand *TotalSize = legalize(Inst->getSizeInBytes());
+  Variable *Dest = Inst->getDest();
+  _sub(esp, TotalSize);
+  _mov(Dest, esp);
+}
+
+void TargetX8632::lowerArithmetic(const InstArithmetic *Inst) {
+  Variable *Dest = Inst->getDest();
+  Operand *Src0 = legalize(Inst->getSrc(0));
+  Operand *Src1 = legalize(Inst->getSrc(1));
+  if (Dest->getType() == IceType_i64) {
+    Variable *DestLo = llvm::cast<Variable>(loOperand(Dest));
+    Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
+    Operand *Src0Lo = loOperand(Src0);
+    Operand *Src0Hi = hiOperand(Src0);
+    Operand *Src1Lo = loOperand(Src1);
+    Operand *Src1Hi = hiOperand(Src1);
+    Variable *T_Lo = NULL, *T_Hi = NULL;
+    switch (Inst->getOp()) {
+    case InstArithmetic::Add:
+      _mov(T_Lo, Src0Lo);
+      _add(T_Lo, Src1Lo);
+      _mov(DestLo, T_Lo);
+      _mov(T_Hi, Src0Hi);
+      _adc(T_Hi, Src1Hi);
+      _mov(DestHi, T_Hi);
+      break;
+    case InstArithmetic::And:
+      _mov(T_Lo, Src0Lo);
+      _and(T_Lo, Src1Lo);
+      _mov(DestLo, T_Lo);
+      _mov(T_Hi, Src0Hi);
+      _and(T_Hi, Src1Hi);
+      _mov(DestHi, T_Hi);
+      break;
+    case InstArithmetic::Or:
+      _mov(T_Lo, Src0Lo);
+      _or(T_Lo, Src1Lo);
+      _mov(DestLo, T_Lo);
+      _mov(T_Hi, Src0Hi);
+      _or(T_Hi, Src1Hi);
+      _mov(DestHi, T_Hi);
+      break;
+    case InstArithmetic::Xor:
+      _mov(T_Lo, Src0Lo);
+      _xor(T_Lo, Src1Lo);
+      _mov(DestLo, T_Lo);
+      _mov(T_Hi, Src0Hi);
+      _xor(T_Hi, Src1Hi);
+      _mov(DestHi, T_Hi);
+      break;
+    case InstArithmetic::Sub:
+      _mov(T_Lo, Src0Lo);
+      _sub(T_Lo, Src1Lo);
+      _mov(DestLo, T_Lo);
+      _mov(T_Hi, Src0Hi);
+      _sbb(T_Hi, Src1Hi);
+      _mov(DestHi, T_Hi);
+      break;
+    case InstArithmetic::Mul: {
+      Variable *T_1 = NULL, *T_2 = NULL, *T_3 = NULL;
+      Variable *T_4Lo = makeReg(IceType_i32, Reg_eax);
+      Variable *T_4Hi = makeReg(IceType_i32, Reg_edx);
+      // gcc does the following:
+      // a=b*c ==>
+      //   t1 = b.hi; t1 *=(imul) c.lo
+      //   t2 = c.hi; t2 *=(imul) b.lo
+      //   t3:eax = b.lo
+      //   t4.hi:edx,t4.lo:eax = t3:eax *(mul) c.lo
+      //   a.lo = t4.lo
+      //   t4.hi += t1
+      //   t4.hi += t2
+      //   a.hi = t4.hi
+      _mov(T_1, Src0Hi);
+      _imul(T_1, Src1Lo);
+      _mov(T_2, Src1Hi);
+      _imul(T_2, Src0Lo);
+      _mov(T_3, Src0Lo, Reg_eax);
+      _mul(T_4Lo, T_3, Src1Lo);
+      // The mul instruction produces two dest variables, edx:eax.  We
+      // create a fake definition of edx to account for this.
+      Context.insert(InstFakeDef::create(Func, T_4Hi, T_4Lo));
+      _mov(DestLo, T_4Lo);
+      _add(T_4Hi, T_1);
+      _add(T_4Hi, T_2);
+      _mov(DestHi, T_4Hi);
+    } break;
+    case InstArithmetic::Shl: {
+      // TODO: Refactor the similarities between Shl, Lshr, and Ashr.
+      // gcc does the following:
+      // a=b<<c ==>
+      //   t1:ecx = c.lo & 0xff
+      //   t2 = b.lo
+      //   t3 = b.hi
+      //   t3 = shld t3, t2, t1
+      //   t2 = shl t2, t1
+      //   test t1, 0x20
+      //   je L1
+      //   use(t3)
+      //   t3 = t2
+      //   t2 = 0
+      // L1:
+      //   a.lo = t2
+      //   a.hi = t3
+      Variable *T_1 = NULL, *T_2 = NULL, *T_3 = NULL;
+      Constant *BitTest = Ctx->getConstantInt(IceType_i32, 0x20);
+      Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+      InstX8632Label *Label = InstX8632Label::create(Func, this);
+      _mov(T_1, Src1Lo, Reg_ecx);
+      _mov(T_2, Src0Lo);
+      _mov(T_3, Src0Hi);
+      _shld(T_3, T_2, T_1);
+      _shl(T_2, T_1);
+      _test(T_1, BitTest);
+      _br(InstX8632Br::Br_e, Label);
+      // Because of the intra-block control flow, we need to fake a use
+      // of T_3 to prevent its earlier definition from being dead-code
+      // eliminated in the presence of its later definition.
+      Context.insert(InstFakeUse::create(Func, T_3));
+      _mov(T_3, T_2);
+      _mov(T_2, Zero);
+      Context.insert(Label);
+      _mov(DestLo, T_2);
+      _mov(DestHi, T_3);
+    } break;
+    case InstArithmetic::Lshr: {
+      // a=b>>c (unsigned) ==>
+      //   t1:ecx = c.lo & 0xff
+      //   t2 = b.lo
+      //   t3 = b.hi
+      //   t2 = shrd t2, t3, t1
+      //   t3 = shr t3, t1
+      //   test t1, 0x20
+      //   je L1
+      //   use(t2)
+      //   t2 = t3
+      //   t3 = 0
+      // L1:
+      //   a.lo = t2
+      //   a.hi = t3
+      Variable *T_1 = NULL, *T_2 = NULL, *T_3 = NULL;
+      Constant *BitTest = Ctx->getConstantInt(IceType_i32, 0x20);
+      Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+      InstX8632Label *Label = InstX8632Label::create(Func, this);
+      _mov(T_1, Src1Lo, Reg_ecx);
+      _mov(T_2, Src0Lo);
+      _mov(T_3, Src0Hi);
+      _shrd(T_2, T_3, T_1);
+      _shr(T_3, T_1);
+      _test(T_1, BitTest);
+      _br(InstX8632Br::Br_e, Label);
+      // Because of the intra-block control flow, we need to fake a use
+      // of T_3 to prevent its earlier definition from being dead-code
+      // eliminated in the presence of its later definition.
+      Context.insert(InstFakeUse::create(Func, T_2));
+      _mov(T_2, T_3);
+      _mov(T_3, Zero);
+      Context.insert(Label);
+      _mov(DestLo, T_2);
+      _mov(DestHi, T_3);
+    } break;
+    case InstArithmetic::Ashr: {
+      // a=b>>c (signed) ==>
+      //   t1:ecx = c.lo & 0xff
+      //   t2 = b.lo
+      //   t3 = b.hi
+      //   t2 = shrd t2, t3, t1
+      //   t3 = sar t3, t1
+      //   test t1, 0x20
+      //   je L1
+      //   use(t2)
+      //   t2 = t3
+      //   t3 = sar t3, 0x1f
+      // L1:
+      //   a.lo = t2
+      //   a.hi = t3
+      Variable *T_1 = NULL, *T_2 = NULL, *T_3 = NULL;
+      Constant *BitTest = Ctx->getConstantInt(IceType_i32, 0x20);
+      Constant *SignExtend = Ctx->getConstantInt(IceType_i32, 0x1f);
+      InstX8632Label *Label = InstX8632Label::create(Func, this);
+      _mov(T_1, Src1Lo, Reg_ecx);
+      _mov(T_2, Src0Lo);
+      _mov(T_3, Src0Hi);
+      _shrd(T_2, T_3, T_1);
+      _sar(T_3, T_1);
+      _test(T_1, BitTest);
+      _br(InstX8632Br::Br_e, Label);
+      // Because of the intra-block control flow, we need to fake a use
+      // of T_3 to prevent its earlier definition from being dead-code
+      // eliminated in the presence of its later definition.
+      Context.insert(InstFakeUse::create(Func, T_2));
+      _mov(T_2, T_3);
+      _sar(T_3, SignExtend);
+      Context.insert(Label);
+      _mov(DestLo, T_2);
+      _mov(DestHi, T_3);
+    } break;
+    case InstArithmetic::Udiv: {
+      const SizeT MaxSrcs = 2;
+      InstCall *Call = makeHelperCall("__udivdi3", Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      Call->addArg(Inst->getSrc(1));
+      lowerCall(Call);
+    } break;
+    case InstArithmetic::Sdiv: {
+      const SizeT MaxSrcs = 2;
+      InstCall *Call = makeHelperCall("__divdi3", Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      Call->addArg(Inst->getSrc(1));
+      lowerCall(Call);
+    } break;
+    case InstArithmetic::Urem: {
+      const SizeT MaxSrcs = 2;
+      InstCall *Call = makeHelperCall("__umoddi3", Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      Call->addArg(Inst->getSrc(1));
+      lowerCall(Call);
+    } break;
+    case InstArithmetic::Srem: {
+      const SizeT MaxSrcs = 2;
+      InstCall *Call = makeHelperCall("__moddi3", Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      Call->addArg(Inst->getSrc(1));
+      lowerCall(Call);
+    } break;
+    case InstArithmetic::Fadd:
+    case InstArithmetic::Fsub:
+    case InstArithmetic::Fmul:
+    case InstArithmetic::Fdiv:
+    case InstArithmetic::Frem:
+      llvm_unreachable("FP instruction with i64 type");
+      break;
+    }
+  } else { // Dest->getType() != IceType_i64
+    Variable *T_edx = NULL;
+    Variable *T = NULL;
+    switch (Inst->getOp()) {
+    case InstArithmetic::Add:
+      _mov(T, Src0);
+      _add(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::And:
+      _mov(T, Src0);
+      _and(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Or:
+      _mov(T, Src0);
+      _or(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Xor:
+      _mov(T, Src0);
+      _xor(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Sub:
+      _mov(T, Src0);
+      _sub(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Mul:
+      // TODO: Optimize for llvm::isa<Constant>(Src1)
+      // TODO: Strength-reduce multiplications by a constant,
+      // particularly -1 and powers of 2.  Advanced: use lea to
+      // multiply by 3, 5, 9.
+      //
+      // The 8-bit version of imul only allows the form "imul r/m8"
+      // where T must be in eax.
+      if (Dest->getType() == IceType_i8)
+        _mov(T, Src0, Reg_eax);
+      else
+        _mov(T, Src0);
+      _imul(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Shl:
+      _mov(T, Src0);
+      if (!llvm::isa<Constant>(Src1))
+        Src1 = legalizeToVar(Src1, false, Reg_ecx);
+      _shl(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Lshr:
+      _mov(T, Src0);
+      if (!llvm::isa<Constant>(Src1))
+        Src1 = legalizeToVar(Src1, false, Reg_ecx);
+      _shr(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Ashr:
+      _mov(T, Src0);
+      if (!llvm::isa<Constant>(Src1))
+        Src1 = legalizeToVar(Src1, false, Reg_ecx);
+      _sar(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Udiv:
+      if (Dest->getType() == IceType_i8) {
+        Variable *T_ah = NULL;
+        Constant *Zero = Ctx->getConstantInt(IceType_i8, 0);
+        _mov(T, Src0, Reg_eax);
+        _mov(T_ah, Zero, Reg_ah);
+        _div(T_ah, Src1, T);
+        Context.insert(InstFakeUse::create(Func, T_ah));
+        _mov(Dest, T);
+      } else {
+        // TODO: fix for 8-bit, see Urem
+        Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+        _mov(T, Src0, Reg_eax);
+        _mov(T_edx, Zero, Reg_edx);
+        _div(T, Src1, T_edx);
+        _mov(Dest, T);
+      }
+      break;
+    case InstArithmetic::Sdiv:
+      T_edx = makeReg(IceType_i32, Reg_edx);
+      _mov(T, Src0, Reg_eax);
+      _cdq(T_edx, T);
+      _idiv(T, Src1, T_edx);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Urem:
+      if (Dest->getType() == IceType_i8) {
+        Variable *T_ah = NULL;
+        Constant *Zero = Ctx->getConstantInt(IceType_i8, 0);
+        _mov(T, Src0, Reg_eax);
+        _mov(T_ah, Zero, Reg_ah);
+        _div(T_ah, Src1, T);
+        _mov(Dest, T_ah);
+      } else {
+        Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+        _mov(T_edx, Zero, Reg_edx);
+        _mov(T, Src0, Reg_eax);
+        _div(T_edx, Src1, T);
+        _mov(Dest, T_edx);
+      }
+      break;
+    case InstArithmetic::Srem:
+      T_edx = makeReg(IceType_i32, Reg_edx);
+      _mov(T, Src0, Reg_eax);
+      _cdq(T_edx, T);
+      _idiv(T_edx, Src1, T);
+      _mov(Dest, T_edx);
+      break;
+    case InstArithmetic::Fadd:
+      _mov(T, Src0);
+      _addss(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Fsub:
+      _mov(T, Src0);
+      _subss(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Fmul:
+      _mov(T, Src0);
+      _mulss(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Fdiv:
+      _mov(T, Src0);
+      _divss(T, Src1);
+      _mov(Dest, T);
+      break;
+    case InstArithmetic::Frem: {
+      const SizeT MaxSrcs = 2;
+      Type Ty = Dest->getType();
+      InstCall *Call =
+          makeHelperCall(Ty == IceType_f32 ? "fmodf" : "fmod", Dest, MaxSrcs);
+      Call->addArg(Src0);
+      Call->addArg(Src1);
+      return lowerCall(Call);
+    } break;
+    }
+  }
+}
+
+void TargetX8632::lowerAssign(const InstAssign *Inst) {
+  Variable *Dest = Inst->getDest();
+  Operand *Src0 = legalize(Inst->getSrc(0));
+  assert(Dest->getType() == Src0->getType());
+  if (Dest->getType() == IceType_i64) {
+    Operand *Src0Lo = loOperand(Src0);
+    Operand *Src0Hi = hiOperand(Src0);
+    Variable *DestLo = llvm::cast<Variable>(loOperand(Dest));
+    Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
+    Variable *T_Lo = NULL, *T_Hi = NULL;
+    _mov(T_Lo, Src0Lo);
+    _mov(DestLo, T_Lo);
+    _mov(T_Hi, Src0Hi);
+    _mov(DestHi, T_Hi);
+  } else {
+    const bool AllowOverlap = true;
+    // RI is either a physical register or an immediate.
+    Operand *RI = legalize(Src0, Legal_Reg | Legal_Imm, AllowOverlap);
+    _mov(Dest, RI);
+  }
+}
+
+void TargetX8632::lowerBr(const InstBr *Inst) {
+  if (Inst->isUnconditional()) {
+    _br(Inst->getTargetUnconditional());
+  } else {
+    Operand *Src0 = legalize(Inst->getCondition());
+    Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+    _cmp(Src0, Zero);
+    _br(InstX8632Br::Br_ne, Inst->getTargetTrue(), Inst->getTargetFalse());
+  }
+}
+
+void TargetX8632::lowerCall(const InstCall *Instr) {
+  // Generate a sequence of push instructions, pushing right to left,
+  // keeping track of stack offsets in case a push involves a stack
+  // operand and we are using an esp-based frame.
+  uint32_t StackOffset = 0;
+  // TODO: If for some reason the call instruction gets dead-code
+  // eliminated after lowering, we would need to ensure that the
+  // pre-call push instructions and the post-call esp adjustment get
+  // eliminated as well.
+  for (SizeT NumArgs = Instr->getNumArgs(), i = 0; i < NumArgs; ++i) {
+    Operand *Arg = legalize(Instr->getArg(NumArgs - i - 1));
+    if (Arg->getType() == IceType_i64) {
+      _push(hiOperand(Arg));
+      _push(loOperand(Arg));
+    } else if (Arg->getType() == IceType_f64) {
+      // If the Arg turns out to be a memory operand, we need to push
+      // 8 bytes, which requires two push instructions.  This ends up
+      // being somewhat clumsy in the current IR, so we use a
+      // workaround.  Force the operand into a (xmm) register, and
+      // then push the register.  An xmm register push is actually not
+      // possible in x86, but the Push instruction emitter handles
+      // this by decrementing the stack pointer and directly writing
+      // the xmm register value.
+      Variable *T = NULL;
+      _mov(T, Arg);
+      _push(T);
+    } else {
+      _push(Arg);
+    }
+    StackOffset += typeWidthInBytesOnStack(Arg->getType());
+  }
+  // Generate the call instruction.  Assign its result to a temporary
+  // with high register allocation weight.
+  Variable *Dest = Instr->getDest();
+  Variable *eax = NULL; // doubles as RegLo as necessary
+  Variable *edx = NULL;
+  if (Dest) {
+    switch (Dest->getType()) {
+    case IceType_NUM:
+      llvm_unreachable("Invalid Call dest type");
+      break;
+    case IceType_void:
+      break;
+    case IceType_i1:
+    case IceType_i8:
+    case IceType_i16:
+    case IceType_i32:
+      eax = makeReg(Dest->getType(), Reg_eax);
+      break;
+    case IceType_i64:
+      eax = makeReg(IceType_i32, Reg_eax);
+      edx = makeReg(IceType_i32, Reg_edx);
+      break;
+    case IceType_f32:
+    case IceType_f64:
+      // Leave eax==edx==NULL, and capture the result with the fstp
+      // instruction.
+      break;
+    }
+  }
+  Operand *CallTarget = legalize(Instr->getCallTarget());
+  Inst *NewCall = InstX8632Call::create(Func, eax, CallTarget);
+  Context.insert(NewCall);
+  if (edx)
+    Context.insert(InstFakeDef::create(Func, edx));
+
+  // Add the appropriate offset to esp.
+  if (StackOffset) {
+    Variable *esp = Func->getTarget()->getPhysicalRegister(Reg_esp);
+    _add(esp, Ctx->getConstantInt(IceType_i32, StackOffset));
+  }
+
+  // Insert a register-kill pseudo instruction.
+  VarList KilledRegs;
+  for (SizeT i = 0; i < ScratchRegs.size(); ++i) {
+    if (ScratchRegs[i])
+      KilledRegs.push_back(Func->getTarget()->getPhysicalRegister(i));
+  }
+  if (!KilledRegs.empty()) {
+    Inst *Kill = InstFakeKill::create(Func, KilledRegs, NewCall);
+    Context.insert(Kill);
+  }
+
+  // Generate a FakeUse to keep the call live if necessary.
+  if (Instr->hasSideEffects() && eax) {
+    Inst *FakeUse = InstFakeUse::create(Func, eax);
+    Context.insert(FakeUse);
+  }
+
+  // Generate Dest=eax assignment.
+  if (Dest && eax) {
+    if (edx) {
+      split64(Dest);
+      Variable *DestLo = Dest->getLo();
+      Variable *DestHi = Dest->getHi();
+      DestLo->setPreferredRegister(eax, false);
+      DestHi->setPreferredRegister(edx, false);
+      _mov(DestLo, eax);
+      _mov(DestHi, edx);
+    } else {
+      Dest->setPreferredRegister(eax, false);
+      _mov(Dest, eax);
+    }
+  }
+
+  // Special treatment for an FP function which returns its result in
+  // st(0).
+  if (Dest &&
+      (Dest->getType() == IceType_f32 || Dest->getType() == IceType_f64)) {
+    _fstp(Dest);
+    // If Dest ends up being a physical xmm register, the fstp emit
+    // code will route st(0) through a temporary stack slot.
+  }
+}
+
+void TargetX8632::lowerCast(const InstCast *Inst) {
+  // a = cast(b) ==> t=cast(b); a=t; (link t->b, link a->t, no overlap)
+  InstCast::OpKind CastKind = Inst->getCastKind();
+  Variable *Dest = Inst->getDest();
+  // Src0RM is the source operand legalized to physical register or memory, but
+  // not immediate, since the relevant x86 native instructions don't allow an
+  // immediate operand.  If the operand is an immediate, we could consider
+  // computing the strength-reduced result at translation time, but we're
+  // unlikely to see something like that in the bitcode that the optimizer
+  // wouldn't have already taken care of.
+  Operand *Src0RM = legalize(Inst->getSrc(0), Legal_Reg | Legal_Mem, true);
+  switch (CastKind) {
+  default:
+    Func->setError("Cast type not supported");
+    return;
+  case InstCast::Sext:
+    if (Dest->getType() == IceType_i64) {
+      // t1=movsx src; t2=t1; t2=sar t2, 31; dst.lo=t1; dst.hi=t2
+      Variable *DestLo = llvm::cast<Variable>(loOperand(Dest));
+      Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
+      Variable *T_Lo = makeReg(DestLo->getType());
+      if (Src0RM->getType() == IceType_i32)
+        _mov(T_Lo, Src0RM);
+      else
+        _movsx(T_Lo, Src0RM);
+      _mov(DestLo, T_Lo);
+      Variable *T_Hi = NULL;
+      Constant *Shift = Ctx->getConstantInt(IceType_i32, 31);
+      _mov(T_Hi, T_Lo);
+      _sar(T_Hi, Shift);
+      _mov(DestHi, T_Hi);
+    } else {
+      // TODO: Sign-extend an i1 via "shl reg, 31; sar reg, 31", and
+      // also copy to the high operand of a 64-bit variable.
+      // t1 = movsx src; dst = t1
+      Variable *T = makeReg(Dest->getType());
+      _movsx(T, Src0RM);
+      _mov(Dest, T);
+    }
+    break;
+  case InstCast::Zext:
+    if (Dest->getType() == IceType_i64) {
+      // t1=movzx src; dst.lo=t1; dst.hi=0
+      Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+      Variable *DestLo = llvm::cast<Variable>(loOperand(Dest));
+      Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
+      Variable *Tmp = makeReg(DestLo->getType());
+      if (Src0RM->getType() == IceType_i32)
+        _mov(Tmp, Src0RM);
+      else
+        _movzx(Tmp, Src0RM);
+      _mov(DestLo, Tmp);
+      _mov(DestHi, Zero);
+    } else if (Src0RM->getType() == IceType_i1) {
+      // t = Src0RM; t &= 1; Dest = t
+      Operand *One = Ctx->getConstantInt(IceType_i32, 1);
+      Variable *T = makeReg(IceType_i32);
+      _movzx(T, Src0RM);
+      _and(T, One);
+      _mov(Dest, T);
+    } else {
+      // t1 = movzx src; dst = t1
+      Variable *T = makeReg(Dest->getType());
+      _movzx(T, Src0RM);
+      _mov(Dest, T);
+    }
+    break;
+  case InstCast::Trunc: {
+    if (Src0RM->getType() == IceType_i64)
+      Src0RM = loOperand(Src0RM);
+    // t1 = trunc Src0RM; Dest = t1
+    Variable *T = NULL;
+    _mov(T, Src0RM);
+    _mov(Dest, T);
+    break;
+  }
+  case InstCast::Fptrunc:
+  case InstCast::Fpext: {
+    // t1 = cvt Src0RM; Dest = t1
+    Variable *T = makeReg(Dest->getType());
+    _cvt(T, Src0RM);
+    _mov(Dest, T);
+    break;
+  }
+  case InstCast::Fptosi:
+    if (Dest->getType() == IceType_i64) {
+      // Use a helper for converting floating-point values to 64-bit
+      // integers.  SSE2 appears to have no way to convert from xmm
+      // registers to something like the edx:eax register pair, and
+      // gcc and clang both want to use x87 instructions complete with
+      // temporary manipulation of the status word.  This helper is
+      // not needed for x86-64.
+      split64(Dest);
+      const SizeT MaxSrcs = 1;
+      Type SrcType = Inst->getSrc(0)->getType();
+      InstCall *Call = makeHelperCall(
+          SrcType == IceType_f32 ? "cvtftosi64" : "cvtdtosi64", Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      lowerCall(Call);
+    } else {
+      // t1.i32 = cvt Src0RM; t2.dest_type = t1; Dest = t2.dest_type
+      Variable *T_1 = makeReg(IceType_i32);
+      Variable *T_2 = makeReg(Dest->getType());
+      _cvt(T_1, Src0RM);
+      _mov(T_2, T_1); // T_1 and T_2 may have different integer types
+      _mov(Dest, T_2);
+      T_2->setPreferredRegister(T_1, true);
+    }
+    break;
+  case InstCast::Fptoui:
+    if (Dest->getType() == IceType_i64 || Dest->getType() == IceType_i32) {
+      // Use a helper for both x86-32 and x86-64.
+      split64(Dest);
+      const SizeT MaxSrcs = 1;
+      Type DestType = Dest->getType();
+      Type SrcType = Src0RM->getType();
+      IceString DstSubstring = (DestType == IceType_i64 ? "64" : "32");
+      IceString SrcSubstring = (SrcType == IceType_f32 ? "f" : "d");
+      // Possibilities are cvtftoui32, cvtdtoui32, cvtftoui64, cvtdtoui64
+      IceString TargetString = "cvt" + SrcSubstring + "toui" + DstSubstring;
+      InstCall *Call = makeHelperCall(TargetString, Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      lowerCall(Call);
+      return;
+    } else {
+      // t1.i32 = cvt Src0RM; t2.dest_type = t1; Dest = t2.dest_type
+      Variable *T_1 = makeReg(IceType_i32);
+      Variable *T_2 = makeReg(Dest->getType());
+      _cvt(T_1, Src0RM);
+      _mov(T_2, T_1); // T_1 and T_2 may have different integer types
+      _mov(Dest, T_2);
+      T_2->setPreferredRegister(T_1, true);
+    }
+    break;
+  case InstCast::Sitofp:
+    if (Src0RM->getType() == IceType_i64) {
+      // Use a helper for x86-32.
+      const SizeT MaxSrcs = 1;
+      Type DestType = Dest->getType();
+      InstCall *Call = makeHelperCall(
+          DestType == IceType_f32 ? "cvtsi64tof" : "cvtsi64tod", Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      lowerCall(Call);
+      return;
+    } else {
+      // Sign-extend the operand.
+      // t1.i32 = movsx Src0RM; t2 = Cvt t1.i32; Dest = t2
+      Variable *T_1 = makeReg(IceType_i32);
+      Variable *T_2 = makeReg(Dest->getType());
+      if (Src0RM->getType() == IceType_i32)
+        _mov(T_1, Src0RM);
+      else
+        _movsx(T_1, Src0RM);
+      _cvt(T_2, T_1);
+      _mov(Dest, T_2);
+    }
+    break;
+  case InstCast::Uitofp:
+    if (Src0RM->getType() == IceType_i64 || Src0RM->getType() == IceType_i32) {
+      // Use a helper for x86-32 and x86-64.  Also use a helper for
+      // i32 on x86-32.
+      const SizeT MaxSrcs = 1;
+      Type DestType = Dest->getType();
+      IceString SrcSubstring = (Src0RM->getType() == IceType_i64 ? "64" : "32");
+      IceString DstSubstring = (DestType == IceType_f32 ? "f" : "d");
+      // Possibilities are cvtui32tof, cvtui32tod, cvtui64tof, cvtui64tod
+      IceString TargetString = "cvtui" + SrcSubstring + "to" + DstSubstring;
+      InstCall *Call = makeHelperCall(TargetString, Dest, MaxSrcs);
+      Call->addArg(Inst->getSrc(0));
+      lowerCall(Call);
+      return;
+    } else {
+      // Zero-extend the operand.
+      // t1.i32 = movzx Src0RM; t2 = Cvt t1.i32; Dest = t2
+      Variable *T_1 = makeReg(IceType_i32);
+      Variable *T_2 = makeReg(Dest->getType());
+      if (Src0RM->getType() == IceType_i32)
+        _mov(T_1, Src0RM);
+      else
+        _movzx(T_1, Src0RM);
+      _cvt(T_2, T_1);
+      _mov(Dest, T_2);
+    }
+    break;
+  case InstCast::Bitcast:
+    if (Dest->getType() == Src0RM->getType()) {
+      InstAssign *Assign = InstAssign::create(Func, Dest, Src0RM);
+      lowerAssign(Assign);
+      llvm_unreachable("Pointer bitcasts aren't lowered correctly.");
+      return;
+    }
+    switch (Dest->getType()) {
+    default:
+      llvm_unreachable("Unexpected Bitcast dest type");
+    case IceType_i32:
+    case IceType_f32: {
+      Type DestType = Dest->getType();
+      Type SrcType = Src0RM->getType();
+      assert((DestType == IceType_i32 && SrcType == IceType_f32) ||
+             (DestType == IceType_f32 && SrcType == IceType_i32));
+      // a.i32 = bitcast b.f32 ==>
+      //   t.f32 = b.f32
+      //   s.f32 = spill t.f32
+      //   a.i32 = s.f32
+      Variable *T = NULL;
+      // TODO: Should be able to force a spill setup by calling legalize() with
+      // Legal_Mem and not Legal_Reg or Legal_Imm.
+      Variable *Spill = Func->makeVariable(SrcType, Context.getNode());
+      Spill->setWeight(RegWeight::Zero);
+      Spill->setPreferredRegister(Dest, true);
+      _mov(T, Src0RM);
+      _mov(Spill, T);
+      _mov(Dest, Spill);
+    } break;
+    case IceType_i64: {
+      assert(Src0RM->getType() == IceType_f64);
+      // a.i64 = bitcast b.f64 ==>
+      //   s.f64 = spill b.f64
+      //   t_lo.i32 = lo(s.f64)
+      //   a_lo.i32 = t_lo.i32
+      //   t_hi.i32 = hi(s.f64)
+      //   a_hi.i32 = t_hi.i32
+      Variable *Spill = Func->makeVariable(IceType_f64, Context.getNode());
+      Spill->setWeight(RegWeight::Zero);
+      Spill->setPreferredRegister(llvm::dyn_cast<Variable>(Src0RM), true);
+      _mov(Spill, Src0RM);
+
+      Variable *DestLo = llvm::cast<Variable>(loOperand(Dest));
+      Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
+      Variable *T_Lo = makeReg(IceType_i32);
+      Variable *T_Hi = makeReg(IceType_i32);
+      VariableSplit *SpillLo =
+          VariableSplit::create(Func, Spill, VariableSplit::Low);
+      VariableSplit *SpillHi =
+          VariableSplit::create(Func, Spill, VariableSplit::High);
+
+      _mov(T_Lo, SpillLo);
+      _mov(DestLo, T_Lo);
+      _mov(T_Hi, SpillHi);
+      _mov(DestHi, T_Hi);
+    } break;
+    case IceType_f64: {
+      assert(Src0RM->getType() == IceType_i64);
+      // a.f64 = bitcast b.i64 ==>
+      //   t_lo.i32 = b_lo.i32
+      //   lo(s.f64) = t_lo.i32
+      //   FakeUse(s.f64)
+      //   t_hi.i32 = b_hi.i32
+      //   hi(s.f64) = t_hi.i32
+      //   a.f64 = s.f64
+      Variable *Spill = Func->makeVariable(IceType_f64, Context.getNode());
+      Spill->setWeight(RegWeight::Zero);
+      Spill->setPreferredRegister(Dest, true);
+
+      Context.insert(InstFakeDef::create(Func, Spill));
+
+      Variable *T_Lo = NULL, *T_Hi = NULL;
+      VariableSplit *SpillLo =
+          VariableSplit::create(Func, Spill, VariableSplit::Low);
+      VariableSplit *SpillHi =
+          VariableSplit::create(Func, Spill, VariableSplit::High);
+      _mov(T_Lo, loOperand(Src0RM));
+      _store(T_Lo, SpillLo);
+      _mov(T_Hi, hiOperand(Src0RM));
+      _store(T_Hi, SpillHi);
+      _mov(Dest, Spill);
+    } break;
+    }
+    break;
+  }
+}
+
+void TargetX8632::lowerFcmp(const InstFcmp *Inst) {
+  Operand *Src0 = Inst->getSrc(0);
+  Operand *Src1 = Inst->getSrc(1);
+  Variable *Dest = Inst->getDest();
+  // Lowering a = fcmp cond, b, c
+  //   ucomiss b, c       /* only if C1 != Br_None */
+  //                      /* but swap b,c order if SwapOperands==true */
+  //   mov a, <default>
+  //   j<C1> label        /* only if C1 != Br_None */
+  //   j<C2> label        /* only if C2 != Br_None */
+  //   FakeUse(a)         /* only if C1 != Br_None */
+  //   mov a, !<default>  /* only if C1 != Br_None */
+  //   label:             /* only if C1 != Br_None */
+  InstFcmp::FCond Condition = Inst->getCondition();
+  size_t Index = static_cast<size_t>(Condition);
+  assert(Index < TableFcmpSize);
+  // The table is indexed by InstFcmp::Condition.  Make sure it didn't fall
+  // out of order.
+  if (TableFcmp[Index].SwapOperands) {
+    Operand *Tmp = Src0;
+    Src0 = Src1;
+    Src1 = Tmp;
+  }
+  bool HasC1 = (TableFcmp[Index].C1 != InstX8632Br::Br_None);
+  bool HasC2 = (TableFcmp[Index].C2 != InstX8632Br::Br_None);
+  if (HasC1) {
+    Src0 = legalize(Src0);
+    Operand *Src1RM = legalize(Src1, Legal_Reg | Legal_Mem);
+    Variable *T = NULL;
+    _mov(T, Src0);
+    _ucomiss(T, Src1RM);
+  }
+  Constant *Default =
+      Ctx->getConstantInt(IceType_i32, TableFcmp[Index].Default);
+  _mov(Dest, Default);
+  if (HasC1) {
+    InstX8632Label *Label = InstX8632Label::create(Func, this);
+    _br(TableFcmp[Index].C1, Label);
+    if (HasC2) {
+      _br(TableFcmp[Index].C2, Label);
+    }
+    Context.insert(InstFakeUse::create(Func, Dest));
+    Constant *NonDefault =
+        Ctx->getConstantInt(IceType_i32, !TableFcmp[Index].Default);
+    _mov(Dest, NonDefault);
+    Context.insert(Label);
+  }
+}
+
+void TargetX8632::lowerIcmp(const InstIcmp *Inst) {
+  Operand *Src0 = legalize(Inst->getSrc(0));
+  Operand *Src1 = legalize(Inst->getSrc(1));
+  Variable *Dest = Inst->getDest();
+
+  // If Src1 is an immediate, or known to be a physical register, we can
+  // allow Src0 to be a memory operand.  Otherwise, Src0 must be copied into
+  // a physical register.  (Actually, either Src0 or Src1 can be chosen for
+  // the physical register, but unfortunately we have to commit to one or
+  // the other before register allocation.)
+  bool IsSrc1ImmOrReg = false;
+  if (llvm::isa<Constant>(Src1))
+    IsSrc1ImmOrReg = true;
+  else if (Variable *Var = llvm::dyn_cast<Variable>(Src1)) {
+    if (Var->hasReg())
+      IsSrc1ImmOrReg = true;
+  }
+
+  // a=icmp cond, b, c ==> cmp b,c; a=1; br cond,L1; FakeUse(a); a=0; L1:
+  Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+  Constant *One = Ctx->getConstantInt(IceType_i32, 1);
+  if (Src0->getType() == IceType_i64) {
+    InstIcmp::ICond Condition = Inst->getCondition();
+    size_t Index = static_cast<size_t>(Condition);
+    assert(Index < TableIcmp64Size);
+    // The table is indexed by InstIcmp::Condition.  Make sure it didn't fall
+    // out of order.
+    Operand *Src1LoRI = legalize(loOperand(Src1), Legal_Reg | Legal_Imm);
+    Operand *Src1HiRI = legalize(hiOperand(Src1), Legal_Reg | Legal_Imm);
+    if (Condition == InstIcmp::Eq || Condition == InstIcmp::Ne) {
+      InstX8632Label *Label = InstX8632Label::create(Func, this);
+      _mov(Dest, (Condition == InstIcmp::Eq ? Zero : One));
+      _cmp(loOperand(Src0), Src1LoRI);
+      _br(InstX8632Br::Br_ne, Label);
+      _cmp(hiOperand(Src0), Src1HiRI);
+      _br(InstX8632Br::Br_ne, Label);
+      Context.insert(InstFakeUse::create(Func, Dest));
+      _mov(Dest, (Condition == InstIcmp::Eq ? One : Zero));
+      Context.insert(Label);
+    } else {
+      InstX8632Label *LabelFalse = InstX8632Label::create(Func, this);
+      InstX8632Label *LabelTrue = InstX8632Label::create(Func, this);
+      _mov(Dest, One);
+      _cmp(hiOperand(Src0), Src1HiRI);
+      _br(TableIcmp64[Index].C1, LabelTrue);
+      _br(TableIcmp64[Index].C2, LabelFalse);
+      _cmp(loOperand(Src0), Src1LoRI);
+      _br(TableIcmp64[Index].C3, LabelTrue);
+      Context.insert(LabelFalse);
+      Context.insert(InstFakeUse::create(Func, Dest));
+      _mov(Dest, Zero);
+      Context.insert(LabelTrue);
+    }
+    return;
+  }
+  // cmp b, c
+  Operand *Src0New =
+      legalize(Src0, IsSrc1ImmOrReg ? Legal_All : Legal_Reg, true);
+  InstX8632Label *Label = InstX8632Label::create(Func, this);
+  _cmp(Src0New, Src1);
+  _mov(Dest, One);
+  _br(getIcmp32Mapping(Inst->getCondition()), Label);
+  Context.insert(InstFakeUse::create(Func, Dest));
+  _mov(Dest, Zero);
+  Context.insert(Label);
+}
+
+void TargetX8632::lowerLoad(const InstLoad *Inst) {
+  // A Load instruction can be treated the same as an Assign
+  // instruction, after the source operand is transformed into an
+  // OperandX8632Mem operand.  Note that the address mode
+  // optimization already creates an OperandX8632Mem operand, so it
+  // doesn't need another level of transformation.
+  Type Ty = Inst->getDest()->getType();
+  Operand *Src0 = Inst->getSourceAddress();
+  // Address mode optimization already creates an OperandX8632Mem
+  // operand, so it doesn't need another level of transformation.
+  if (!llvm::isa<OperandX8632Mem>(Src0)) {
+    Variable *Base = llvm::dyn_cast<Variable>(Src0);
+    Constant *Offset = llvm::dyn_cast<Constant>(Src0);
+    assert(Base || Offset);
+    Src0 = OperandX8632Mem::create(Func, Ty, Base, Offset);
+  }
+
+  InstAssign *Assign = InstAssign::create(Func, Inst->getDest(), Src0);
+  lowerAssign(Assign);
+}
+
+void TargetX8632::lowerPhi(const InstPhi * /*Inst*/) {
+  Func->setError("Phi lowering not implemented");
+}
+
+void TargetX8632::lowerRet(const InstRet *Inst) {
+  Variable *Reg = NULL;
+  if (Inst->hasRetValue()) {
+    Operand *Src0 = legalize(Inst->getRetValue());
+    if (Src0->getType() == IceType_i64) {
+      Variable *eax = legalizeToVar(loOperand(Src0), false, Reg_eax);
+      Variable *edx = legalizeToVar(hiOperand(Src0), false, Reg_edx);
+      Reg = eax;
+      Context.insert(InstFakeUse::create(Func, edx));
+    } else if (Src0->getType() == IceType_f32 ||
+               Src0->getType() == IceType_f64) {
+      _fld(Src0);
+    } else {
+      _mov(Reg, Src0, Reg_eax);
+    }
+  }
+  _ret(Reg);
+  // Add a fake use of esp to make sure esp stays alive for the entire
+  // function.  Otherwise post-call esp adjustments get dead-code
+  // eliminated.  TODO: Are there more places where the fake use
+  // should be inserted?  E.g. "void f(int n){while(1) g(n);}" may not
+  // have a ret instruction.
+  Variable *esp = Func->getTarget()->getPhysicalRegister(Reg_esp);
+  Context.insert(InstFakeUse::create(Func, esp));
+}
+
+void TargetX8632::lowerSelect(const InstSelect *Inst) {
+  // a=d?b:c ==> cmp d,0; a=b; jne L1; FakeUse(a); a=c; L1:
+  Variable *Dest = Inst->getDest();
+  Operand *SrcT = Inst->getTrueOperand();
+  Operand *SrcF = Inst->getFalseOperand();
+  Operand *Condition = legalize(Inst->getCondition());
+  Constant *Zero = Ctx->getConstantInt(IceType_i32, 0);
+  InstX8632Label *Label = InstX8632Label::create(Func, this);
+
+  if (Dest->getType() == IceType_i64) {
+    Variable *DestLo = llvm::cast<Variable>(loOperand(Dest));
+    Variable *DestHi = llvm::cast<Variable>(hiOperand(Dest));
+    Operand *SrcLoRI = legalize(loOperand(SrcT), Legal_Reg | Legal_Imm, true);
+    Operand *SrcHiRI = legalize(hiOperand(SrcT), Legal_Reg | Legal_Imm, true);
+    _cmp(Condition, Zero);
+    _mov(DestLo, SrcLoRI);
+    _mov(DestHi, SrcHiRI);
+    _br(InstX8632Br::Br_ne, Label);
+    Context.insert(InstFakeUse::create(Func, DestLo));
+    Context.insert(InstFakeUse::create(Func, DestHi));
+    Operand *SrcFLo = loOperand(SrcF);
+    Operand *SrcFHi = hiOperand(SrcF);
+    SrcLoRI = legalize(SrcFLo, Legal_Reg | Legal_Imm, true);
+    SrcHiRI = legalize(SrcFHi, Legal_Reg | Legal_Imm, true);
+    _mov(DestLo, SrcLoRI);
+    _mov(DestHi, SrcHiRI);
+  } else {
+    _cmp(Condition, Zero);
+    SrcT = legalize(SrcT, Legal_Reg | Legal_Imm, true);
+    _mov(Dest, SrcT);
+    _br(InstX8632Br::Br_ne, Label);
+    Context.insert(InstFakeUse::create(Func, Dest));
+    SrcF = legalize(SrcF, Legal_Reg | Legal_Imm, true);
+    _mov(Dest, SrcF);
+  }
+
+  Context.insert(Label);
+}
+
+void TargetX8632::lowerStore(const InstStore *Inst) {
+  Operand *Value = Inst->getData();
+  Operand *Addr = Inst->getAddr();
+  OperandX8632Mem *NewAddr = llvm::dyn_cast<OperandX8632Mem>(Addr);
+  // Address mode optimization already creates an OperandX8632Mem
+  // operand, so it doesn't need another level of transformation.
+  if (!NewAddr) {
+    // The address will be either a constant (which represents a global
+    // variable) or a variable, so either the Base or Offset component
+    // of the OperandX8632Mem will be set.
+    Variable *Base = llvm::dyn_cast<Variable>(Addr);
+    Constant *Offset = llvm::dyn_cast<Constant>(Addr);
+    assert(Base || Offset);
+    NewAddr = OperandX8632Mem::create(Func, Value->getType(), Base, Offset);
+  }
+  NewAddr = llvm::cast<OperandX8632Mem>(legalize(NewAddr));
+
+  if (NewAddr->getType() == IceType_i64) {
+    Value = legalize(Value);
+    Operand *ValueHi = legalize(hiOperand(Value), Legal_Reg | Legal_Imm, true);
+    Operand *ValueLo = legalize(loOperand(Value), Legal_Reg | Legal_Imm, true);
+    _store(ValueHi, llvm::cast<OperandX8632Mem>(hiOperand(NewAddr)));
+    _store(ValueLo, llvm::cast<OperandX8632Mem>(loOperand(NewAddr)));
+  } else {
+    Value = legalize(Value, Legal_Reg | Legal_Imm, true);
+    _store(Value, NewAddr);
+  }
+}
+
+void TargetX8632::lowerSwitch(const InstSwitch *Inst) {
+  // This implements the most naive possible lowering.
+  // cmp a,val[0]; jeq label[0]; cmp a,val[1]; jeq label[1]; ... jmp default
+  Operand *Src0 = Inst->getComparison();
+  SizeT NumCases = Inst->getNumCases();
+  // OK, we'll be slightly less naive by forcing Src into a physical
+  // register if there are 2 or more uses.
+  if (NumCases >= 2)
+    Src0 = legalizeToVar(Src0, true);
+  else
+    Src0 = legalize(Src0, Legal_All, true);
+  for (SizeT I = 0; I < NumCases; ++I) {
+    Operand *Value = Ctx->getConstantInt(IceType_i32, Inst->getValue(I));
+    _cmp(Src0, Value);
+    _br(InstX8632Br::Br_e, Inst->getLabel(I));
+  }
+
+  _br(Inst->getLabelDefault());
+}
+
+void TargetX8632::lowerUnreachable(const InstUnreachable * /*Inst*/) {
+  const SizeT MaxSrcs = 0;
+  Variable *Dest = NULL;
+  InstCall *Call = makeHelperCall("ice_unreachable", Dest, MaxSrcs);
+  lowerCall(Call);
+}
+
+Operand *TargetX8632::legalize(Operand *From, LegalMask Allowed,
+                               bool AllowOverlap, int32_t RegNum) {
+  assert(Allowed & Legal_Reg);
+  assert(RegNum == Variable::NoRegister || Allowed == Legal_Reg);
+  if (OperandX8632Mem *Mem = llvm::dyn_cast<OperandX8632Mem>(From)) {
+    Variable *Base = Mem->getBase();
+    Variable *Index = Mem->getIndex();
+    Variable *RegBase = Base;
+    Variable *RegIndex = Index;
+    if (Base) {
+      RegBase = legalizeToVar(Base, true);
+    }
+    if (Index) {
+      RegIndex = legalizeToVar(Index, true);
+    }
+    if (Base != RegBase || Index != RegIndex) {
+      From =
+          OperandX8632Mem::create(Func, Mem->getType(), RegBase,
+                                  Mem->getOffset(), RegIndex, Mem->getShift());
+    }
+
+    if (!(Allowed & Legal_Mem)) {
+      Variable *Reg = makeReg(From->getType(), RegNum);
+      _mov(Reg, From, RegNum);
+      From = Reg;
+    }
+    return From;
+  }
+  if (llvm::isa<Constant>(From)) {
+    if (!(Allowed & Legal_Imm)) {
+      Variable *Reg = makeReg(From->getType(), RegNum);
+      _mov(Reg, From);
+      From = Reg;
+    }
+    return From;
+  }
+  if (Variable *Var = llvm::dyn_cast<Variable>(From)) {
+    // We need a new physical register for the operand if:
+    //   Mem is not allowed and Var->getRegNum() is unknown, or
+    //   RegNum is required and Var->getRegNum() doesn't match.
+    if ((!(Allowed & Legal_Mem) && !Var->hasReg()) ||
+        (RegNum != Variable::NoRegister && RegNum != Var->getRegNum())) {
+      Variable *Reg = makeReg(From->getType(), RegNum);
+      if (RegNum == Variable::NoRegister) {
+        Reg->setPreferredRegister(Var, AllowOverlap);
+      }
+      _mov(Reg, From);
+      From = Reg;
+    }
+    return From;
+  }
+  llvm_unreachable("Unhandled operand kind in legalize()");
+  return From;
+}
+
+Variable *TargetX8632::legalizeToVar(Operand *From, bool AllowOverlap,
+                                     int32_t RegNum) {
+  return llvm::cast<Variable>(legalize(From, Legal_Reg, AllowOverlap, RegNum));
+}
+
+Variable *TargetX8632::makeReg(Type Type, int32_t RegNum) {
+  Variable *Reg = Func->makeVariable(Type, Context.getNode());
+  if (RegNum == Variable::NoRegister)
+    Reg->setWeightInfinite();
+  else
+    Reg->setRegNum(RegNum);
+  return Reg;
+}
+
+void TargetX8632::postLower() {
+  if (Ctx->getOptLevel() != Opt_m1)
+    return;
+  // TODO: Avoid recomputing WhiteList every instruction.
+  llvm::SmallBitVector WhiteList = getRegisterSet(RegSet_All, RegSet_None);
+  // Make one pass to black-list pre-colored registers.  TODO: If
+  // there was some prior register allocation pass that made register
+  // assignments, those registers need to be black-listed here as
+  // well.
+  for (InstList::iterator I = Context.getCur(), E = Context.getEnd(); I != E;
+       ++I) {
+    const Inst *Inst = *I;
+    if (Inst->isDeleted())
+      continue;
+    if (llvm::isa<InstFakeKill>(Inst))
+      continue;
+    SizeT VarIndex = 0;
+    for (SizeT SrcNum = 0; SrcNum < Inst->getSrcSize(); ++SrcNum) {
+      Operand *Src = Inst->getSrc(SrcNum);
+      SizeT NumVars = Src->getNumVars();
+      for (SizeT J = 0; J < NumVars; ++J, ++VarIndex) {
+        const Variable *Var = Src->getVar(J);
+        if (!Var->hasReg())
+          continue;
+        WhiteList[Var->getRegNum()] = false;
+      }
+    }
+  }
+  // The second pass colors infinite-weight variables.
+  llvm::SmallBitVector AvailableRegisters = WhiteList;
+  for (InstList::iterator I = Context.getCur(), E = Context.getEnd(); I != E;
+       ++I) {
+    const Inst *Inst = *I;
+    if (Inst->isDeleted())
+      continue;
+    SizeT VarIndex = 0;
+    for (SizeT SrcNum = 0; SrcNum < Inst->getSrcSize(); ++SrcNum) {
+      Operand *Src = Inst->getSrc(SrcNum);
+      SizeT NumVars = Src->getNumVars();
+      for (SizeT J = 0; J < NumVars; ++J, ++VarIndex) {
+        Variable *Var = Src->getVar(J);
+        if (Var->hasReg())
+          continue;
+        if (!Var->getWeight().isInf())
+          continue;
+        llvm::SmallBitVector AvailableTypedRegisters =
+            AvailableRegisters & getRegisterSetForType(Var->getType());
+        if (!AvailableTypedRegisters.any()) {
+          // This is a hack in case we run out of physical registers
+          // due to an excessive number of "push" instructions from
+          // lowering a call.
+          AvailableRegisters = WhiteList;
+          AvailableTypedRegisters =
+              AvailableRegisters & getRegisterSetForType(Var->getType());
+        }
+        assert(AvailableTypedRegisters.any());
+        int32_t RegNum = AvailableTypedRegisters.find_first();
+        Var->setRegNum(RegNum);
+        AvailableRegisters[RegNum] = false;
+      }
+    }
+  }
+}
+
+} // end of namespace Ice