Add a basic TargetARM32 skeleton which knows nothing.

src/IceTargetLoweringARM32.cpp

+//===- subzero/src/IceTargetLoweringARM32.cpp - ARM32 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 TargetLoweringARM32 class, which

[Jim Stichnoth, 2015/04/17 19:16:01]

Reformat to 80-col lines?  (this is probably an artifact of the old name
"IceTargetLoweringX8632" plus emacs fill column = 70)

[jvoung (off chromium), 2015/04/21 17:05:30]

Done.

+// consists almost entirely of the lowering sequence for each
+// high-level instruction.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/MathExtras.h"
+
+#include "IceCfg.h"
+#include "IceCfgNode.h"
+#include "IceClFlags.h"
+#include "IceDefs.h"
+#include "IceELFObjectWriter.h"
+#include "IceGlobalInits.h"
+#include "IceInstARM32.h"
+#include "IceLiveness.h"
+#include "IceOperand.h"
+#include "IceRegistersARM32.h"
+#include "IceTargetLoweringARM32.def"
+#include "IceTargetLoweringARM32.h"
+#include "IceUtils.h"
+
+namespace Ice {
+
+TargetARM32::TargetARM32(Cfg *Func)
+    : TargetLowering(Func), UsesFramePointer(false), NextLabelNumber(0) {
+  // TODO: Don't initialize IntegerRegisters and friends every time.
+  // Instead, initialize in some sort of static initializer for the
+  // class.
+  llvm::SmallBitVector IntegerRegisters(RegARM32::Reg_NUM);
+  llvm::SmallBitVector FloatRegisters(RegARM32::Reg_NUM);
+  llvm::SmallBitVector VectorRegisters(RegARM32::Reg_NUM);
+  llvm::SmallBitVector InvalidRegisters(RegARM32::Reg_NUM);
+  ScratchRegs.resize(RegARM32::Reg_NUM);
+#define X(val, encode, name, scratch, preserved, stackptr, frameptr, isInt,    \
+          isFP)                                                                \
+  IntegerRegisters[RegARM32::val] = isInt;                                     \
+  FloatRegisters[RegARM32::val] = isFP;                                        \
+  VectorRegisters[RegARM32::val] = isFP;                                       \
+  ScratchRegs[RegARM32::val] = scratch;
+  REGARM32_TABLE;
+#undef X
+  TypeToRegisterSet[IceType_void] = InvalidRegisters;
+  TypeToRegisterSet[IceType_i1] = IntegerRegisters;
+  TypeToRegisterSet[IceType_i8] = IntegerRegisters;
+  TypeToRegisterSet[IceType_i16] = IntegerRegisters;
+  TypeToRegisterSet[IceType_i32] = IntegerRegisters;
+  TypeToRegisterSet[IceType_i64] = IntegerRegisters;
+  TypeToRegisterSet[IceType_f32] = FloatRegisters;
+  TypeToRegisterSet[IceType_f64] = FloatRegisters;
+  TypeToRegisterSet[IceType_v4i1] = VectorRegisters;
+  TypeToRegisterSet[IceType_v8i1] = VectorRegisters;
+  TypeToRegisterSet[IceType_v16i1] = VectorRegisters;
+  TypeToRegisterSet[IceType_v16i8] = VectorRegisters;
+  TypeToRegisterSet[IceType_v8i16] = VectorRegisters;
+  TypeToRegisterSet[IceType_v4i32] = VectorRegisters;
+  TypeToRegisterSet[IceType_v4f32] = VectorRegisters;
+}
+
+void TargetARM32::translateO2() {
+  TimerMarker T(TimerStack::TT_O2, Func);
+
+  // TODO: share passes with X86?

[Jim Stichnoth, 2015/04/17 19:16:01]

Definitely.  This would presumably be done as part of
https://code.google.com/p/nativeclient/issues/detail?id=4094 .  Maybe note the
issue here

[jvoung (off chromium), 2015/04/21 17:05:30]

Done.

+
+  if (!Ctx->getFlags().getPhiEdgeSplit()) {
+    // Lower Phi instructions.
+    Func->placePhiLoads();
+    if (Func->hasError())
+      return;
+    Func->placePhiStores();
+    if (Func->hasError())
+      return;
+    Func->deletePhis();
+    if (Func->hasError())
+      return;
+    Func->dump("After Phi lowering");
+  }
+
+  // Address mode optimization.
+  Func->getVMetadata()->init(VMK_SingleDefs);
+  Func->doAddressOpt();
+
+  // Argument lowering
+  Func->doArgLowering();
+
+  // Target lowering.  This requires liveness analysis for some parts
+  // of the lowering decisions, such as compare/branch fusing.  If
+  // non-lightweight liveness analysis is used, the instructions need
+  // to be renumbered first.  TODO: This renumbering should only be
+  // necessary if we're actually calculating live intervals, which we
+  // only do for register allocation.
+  Func->renumberInstructions();
+  if (Func->hasError())
+    return;
+
+  // TODO: It should be sufficient to use the fastest liveness
+  // calculation, i.e. livenessLightweight().  However, for some
+  // reason that slows down the rest of the translation.  Investigate.
+  Func->liveness(Liveness_Basic);
+  if (Func->hasError())
+    return;
+  Func->dump("After ARM32 address mode opt");
+
+  Func->genCode();
+  if (Func->hasError())
+    return;
+  Func->dump("After ARM32 codegen");
+
+  // Register allocation.  This requires instruction renumbering and
+  // full liveness analysis.
+  Func->renumberInstructions();
+  if (Func->hasError())
+    return;
+  Func->liveness(Liveness_Intervals);
+  if (Func->hasError())
+    return;
+  // Validate the live range computations.  The expensive validation
+  // call is deliberately only made when assertions are enabled.
+  assert(Func->validateLiveness());
+  // The post-codegen dump is done here, after liveness analysis and
+  // associated cleanup, to make the dump cleaner and more useful.
+  Func->dump("After initial ARM32 codegen");
+  Func->getVMetadata()->init(VMK_All);
+  regAlloc(RAK_Global);
+  if (Func->hasError())
+    return;
+  Func->dump("After linear scan regalloc");
+
+  if (Ctx->getFlags().getPhiEdgeSplit()) {
+    Func->advancedPhiLowering();
+    Func->dump("After advanced Phi lowering");
+  }
+
+  // Stack frame mapping.
+  Func->genFrame();
+  if (Func->hasError())
+    return;
+  Func->dump("After stack frame mapping");
+
+  Func->contractEmptyNodes();
+  Func->reorderNodes();
+
+  // Branch optimization.  This needs to be done just before code
+  // emission.  In particular, no transformations that insert or
+  // reorder CfgNodes should be done after branch optimization.  We go
+  // ahead and do it before nop insertion to reduce the amount of work
+  // needed for searching for opportunities.
+  Func->doBranchOpt();
+  Func->dump("After branch optimization");
+
+  // Nop insertion
+  if (Ctx->getFlags().shouldDoNopInsertion()) {
+    Func->doNopInsertion();
+  }
+}
+
+void TargetARM32::translateOm1() {
+  TimerMarker T(TimerStack::TT_Om1, Func);
+
+  // TODO: share passes with X86?
+
+  Func->placePhiLoads();
+  if (Func->hasError())
+    return;
+  Func->placePhiStores();
+  if (Func->hasError())
+    return;
+  Func->deletePhis();
+  if (Func->hasError())
+    return;
+  Func->dump("After Phi lowering");
+
+  Func->doArgLowering();
+
+  Func->genCode();
+  if (Func->hasError())
+    return;
+  Func->dump("After initial ARM32 codegen");
+
+  regAlloc(RAK_InfOnly);
+  if (Func->hasError())
+    return;
+  Func->dump("After regalloc of infinite-weight variables");
+
+  Func->genFrame();
+  if (Func->hasError())
+    return;
+  Func->dump("After stack frame mapping");
+
+  // Nop insertion
+  if (Ctx->getFlags().shouldDoNopInsertion()) {
+    Func->doNopInsertion();
+  }
+}
+
+bool TargetARM32::doBranchOpt(Inst *I, const CfgNode *NextNode) {
+  (void)I;
+  (void)NextNode;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+IceString TargetARM32::RegNames[] = {
+#define X(val, encode, name, scratch, preserved, stackptr, frameptr, isInt,    \
+          isFP)                                                                \
+  name,
+    REGARM32_TABLE
+#undef X
+};
+
+IceString TargetARM32::getRegName(SizeT RegNum, Type Ty) const {
+  assert(RegNum < RegARM32::Reg_NUM);
+  (void)Ty;
+  return RegNames[RegNum];
+}
+
+Variable *TargetARM32::getPhysicalRegister(SizeT RegNum, Type Ty) {
+  if (Ty == IceType_void)
+    Ty = IceType_i32;
+  if (PhysicalRegisters[Ty].empty())
+    PhysicalRegisters[Ty].resize(RegARM32::Reg_NUM);
+  assert(RegNum < PhysicalRegisters[Ty].size());
+  Variable *Reg = PhysicalRegisters[Ty][RegNum];
+  if (Reg == nullptr) {
+    Reg = Func->makeVariable(Ty);
+    Reg->setRegNum(RegNum);
+    PhysicalRegisters[Ty][RegNum] = Reg;
+    // Specially mark SP as an "argument" so that it is considered
+    // live upon function entry.
+    if (RegNum == RegARM32::Reg_sp) {
+      Func->addImplicitArg(Reg);
+      Reg->setIgnoreLiveness();
+    }
+  }
+  return Reg;
+}
+
+void TargetARM32::emitVariable(const Variable *Var) const {
+  Ostream &Str = Ctx->getStrEmit();
+  (void)Var;
+  (void)Str;
+  llvm::report_fatal_error("emitVariable: Not yet implemented");
+}
+
+void TargetARM32::lowerArguments() {
+  llvm::report_fatal_error("lowerArguments: Not yet implemented");
+}
+
+Type TargetARM32::stackSlotType() { return IceType_i32; }
+
+void TargetARM32::addProlog(CfgNode *Node) {
+  (void)Node;
+  llvm::report_fatal_error("addProlog: Not yet implemented");
+}
+
+void TargetARM32::addEpilog(CfgNode *Node) {
+  (void)Node;
+  llvm::report_fatal_error("addEpilog: Not yet implemented");
+}
+
+llvm::SmallBitVector TargetARM32::getRegisterSet(RegSetMask Include,
+                                                 RegSetMask Exclude) const {
+  llvm::SmallBitVector Registers(RegARM32::Reg_NUM);
+
+#define X(val, encode, name, scratch, preserved, stackptr, frameptr, isInt,    \
+          isFP)                                                                \
+  if (scratch && (Include & RegSet_CallerSave))                                \
+    Registers[RegARM32::val] = true;                                           \
+  if (preserved && (Include & RegSet_CalleeSave))                              \
+    Registers[RegARM32::val] = true;                                           \
+  if (stackptr && (Include & RegSet_StackPointer))                             \
+    Registers[RegARM32::val] = true;                                           \
+  if (frameptr && (Include & RegSet_FramePointer))                             \
+    Registers[RegARM32::val] = true;                                           \
+  if (scratch && (Exclude & RegSet_CallerSave))                                \
+    Registers[RegARM32::val] = false;                                          \
+  if (preserved && (Exclude & RegSet_CalleeSave))                              \
+    Registers[RegARM32::val] = false;                                          \
+  if (stackptr && (Exclude & RegSet_StackPointer))                             \
+    Registers[RegARM32::val] = false;                                          \
+  if (frameptr && (Exclude & RegSet_FramePointer))                             \
+    Registers[RegARM32::val] = false;
+
+  REGARM32_TABLE
+
+#undef X
+
+  return Registers;
+}
+
+void TargetARM32::lowerAlloca(const InstAlloca *Inst) {
+  UsesFramePointer = true;
+  // Conservatively require the stack to be aligned.  Some stack
+  // adjustment operations implemented below assume that the stack is
+  // aligned before the alloca.  All the alloca code ensures that the
+  // stack alignment is preserved after the alloca.  The stack alignment
+  // restriction can be relaxed in some cases.
+  NeedsStackAlignment = true;
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerArithmetic(const InstArithmetic *Inst) {
+  switch (Inst->getOp()) {
+  case InstArithmetic::_num:
+    llvm_unreachable("Unknown arithmetic operator");
+    break;
+  case InstArithmetic::Add:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::And:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Or:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Xor:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Sub:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Mul:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Shl:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Lshr:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Ashr:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Udiv:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Sdiv:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Urem:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Srem:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Fadd:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Fsub:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Fmul:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Fdiv:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstArithmetic::Frem:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  }
+}
+
+void TargetARM32::lowerAssign(const InstAssign *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerBr(const InstBr *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerCall(const InstCall *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerCast(const InstCast *Inst) {
+  InstCast::OpKind CastKind = Inst->getCastKind();
+  switch (CastKind) {
+  default:
+    Func->setError("Cast type not supported");
+    return;
+  case InstCast::Sext: {
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  }
+  case InstCast::Zext: {
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  }
+  case InstCast::Trunc: {
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  }
+  case InstCast::Fptrunc:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstCast::Fpext: {
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  }
+  case InstCast::Fptosi:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstCast::Fptoui:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstCast::Sitofp:
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  case InstCast::Uitofp: {
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  }
+  case InstCast::Bitcast: {
+    llvm::report_fatal_error("Not yet implemented");
+    break;
+  }
+  }
+}
+
+void TargetARM32::lowerExtractElement(const InstExtractElement *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerFcmp(const InstFcmp *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerIcmp(const InstIcmp *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerInsertElement(const InstInsertElement *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerIntrinsicCall(const InstIntrinsicCall *Instr) {
+  switch (Intrinsics::IntrinsicID ID = Instr->getIntrinsicInfo().ID) {
+  case Intrinsics::AtomicCmpxchg: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::AtomicFence:
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  case Intrinsics::AtomicFenceAll:
+    // NOTE: FenceAll should prevent and load/store from being moved
+    // across the fence (both atomic and non-atomic). The InstARM32Mfence
+    // instruction is currently marked coarsely as "HasSideEffects".
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  case Intrinsics::AtomicIsLockFree: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::AtomicLoad: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::AtomicRMW:
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  case Intrinsics::AtomicStore: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Bswap: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Ctpop: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Ctlz: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Cttz: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Fabs: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Longjmp: {
+    InstCall *Call = makeHelperCall(H_call_longjmp, nullptr, 2);
+    Call->addArg(Instr->getArg(0));
+    Call->addArg(Instr->getArg(1));
+    lowerCall(Call);
+    return;
+  }
+  case Intrinsics::Memcpy: {
+    // In the future, we could potentially emit an inline memcpy/memset, etc.
+    // for intrinsic calls w/ a known length.
+    InstCall *Call = makeHelperCall(H_call_memcpy, nullptr, 3);
+    Call->addArg(Instr->getArg(0));
+    Call->addArg(Instr->getArg(1));
+    Call->addArg(Instr->getArg(2));
+    lowerCall(Call);
+    return;
+  }
+  case Intrinsics::Memmove: {
+    InstCall *Call = makeHelperCall(H_call_memmove, nullptr, 3);
+    Call->addArg(Instr->getArg(0));
+    Call->addArg(Instr->getArg(1));
+    Call->addArg(Instr->getArg(2));
+    lowerCall(Call);
+    return;
+  }
+  case Intrinsics::Memset: {
+    // The value operand needs to be extended to a stack slot size
+    // because the PNaCl ABI requires arguments to be at least 32 bits
+    // wide.
+    Operand *ValOp = Instr->getArg(1);
+    assert(ValOp->getType() == IceType_i8);
+    Variable *ValExt = Func->makeVariable(stackSlotType());
+    lowerCast(InstCast::create(Func, InstCast::Zext, ValExt, ValOp));
+    InstCall *Call = makeHelperCall(H_call_memset, nullptr, 3);
+    Call->addArg(Instr->getArg(0));
+    Call->addArg(ValExt);
+    Call->addArg(Instr->getArg(2));
+    lowerCall(Call);
+    return;
+  }
+  case Intrinsics::NaClReadTP: {
+    if (Ctx->getFlags().getUseSandboxing()) {
+      llvm::report_fatal_error("Not yet implemented");
+    } else {
+      InstCall *Call = makeHelperCall(H_call_read_tp, Instr->getDest(), 0);
+      lowerCall(Call);
+    }
+    return;
+  }
+  case Intrinsics::Setjmp: {
+    InstCall *Call = makeHelperCall(H_call_setjmp, Instr->getDest(), 1);
+    Call->addArg(Instr->getArg(0));
+    lowerCall(Call);
+    return;
+  }
+  case Intrinsics::Sqrt: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Stacksave: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Stackrestore: {
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  }
+  case Intrinsics::Trap:
+    llvm::report_fatal_error("Not yet implemented");
+    return;
+  case Intrinsics::UnknownIntrinsic:
+    Func->setError("Should not be lowering UnknownIntrinsic");
+    return;
+  }
+  return;
+}
+
+void TargetARM32::lowerLoad(const InstLoad *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::doAddressOptLoad() {
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::randomlyInsertNop(float Probability) {
+  RandomNumberGeneratorWrapper RNG(Ctx->getRNG());
+  if (RNG.getTrueWithProbability(Probability)) {
+    llvm::report_fatal_error("Not yet implemented");
+  }
+}
+
+void TargetARM32::lowerPhi(const InstPhi * /*Inst*/) {
+  Func->setError("Phi found in regular instruction list");
+}
+
+void TargetARM32::lowerRet(const InstRet *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerSelect(const InstSelect *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerStore(const InstStore *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::doAddressOptStore() {
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerSwitch(const InstSwitch *Inst) {
+  (void)Inst;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::lowerUnreachable(const InstUnreachable * /*Inst*/) {
+  llvm_unreachable("Not yet implemented");
+}
+
+// Turn an i64 Phi instruction into a pair of i32 Phi instructions, to
+// preserve integrity of liveness analysis.  Undef values are also
+// turned into zeroes, since loOperand() and hiOperand() don't expect
+// Undef input.
+void TargetARM32::prelowerPhis() {
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+// Lower the pre-ordered list of assignments into mov instructions.
+// Also has to do some ad-hoc register allocation as necessary.
+void TargetARM32::lowerPhiAssignments(CfgNode *Node,
+                                      const AssignList &Assignments) {
+  (void)Node;
+  (void)Assignments;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::postLower() {
+  if (Ctx->getFlags().getOptLevel() == Opt_m1)
+    return;
+  // Find two-address non-SSA instructions where Dest==Src0, and set
+  // the DestNonKillable flag to keep liveness analysis consistent.
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetARM32::makeRandomRegisterPermutation(
+    llvm::SmallVectorImpl<int32_t> &Permutation,
+    const llvm::SmallBitVector &ExcludeRegisters) const {
+  (void)Permutation;
+  (void)ExcludeRegisters;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+/* TODO(jvoung): avoid duplicate symbols with multiple targets.
+void ConstantUndef::emitWithoutDollar(GlobalContext *) const {
+  llvm_unreachable("Not expecting to emitWithoutDollar undef");
+}
+
+void ConstantUndef::emit(GlobalContext *) const {
+  llvm_unreachable("undef value encountered by emitter.");
+}
+*/
+
+TargetDataARM32::TargetDataARM32(GlobalContext *Ctx)
+    : TargetDataLowering(Ctx) {}
+
+void TargetDataARM32::lowerGlobal(const VariableDeclaration &Var) const {
+  (void)Var;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+void TargetDataARM32::lowerGlobals(
+    std::unique_ptr<VariableDeclarationList> Vars) const {
+  switch (Ctx->getFlags().getOutFileType()) {
+  case FT_Elf: {
+    ELFObjectWriter *Writer = Ctx->getObjectWriter();
+    Writer->writeDataSection(*Vars, llvm::ELF::R_ARM_ABS32);
+  } break;
+  case FT_Asm:
+  case FT_Iasm: {
+    const IceString &TranslateOnly = Ctx->getFlags().getTranslateOnly();
+    OstreamLocker L(Ctx);
+    for (const VariableDeclaration *Var : *Vars) {
+      if (GlobalContext::matchSymbolName(Var->getName(), TranslateOnly)) {
+        lowerGlobal(*Var);
+      }
+    }
+  } break;
+  }
+}
+
+void TargetDataARM32::lowerConstants() const {
+  if (Ctx->getFlags().getDisableTranslation())
+    return;
+  llvm::report_fatal_error("Not yet implemented");
+}
+
+} // end of namespace Ice