Add AArch64 as an experimental target.

This patch adds support for AArch64 (ARM's 64-bit architecture) to
LLVM in the "experimental" category. Currently, it won't be built
unless requested explicitly.

This initial commit should have support for:
    + Assembly of all scalar (i.e. non-NEON, non-Crypto) instructions
      (except the late addition CRC instructions).
    + CodeGen features required for C++03 and C99.
    + Compilation for the "small" memory model: code+static data <
      4GB.
    + Absolute and position-independent code.
    + GNU-style (i.e. "__thread") TLS.
    + Debugging information.

The principal omission, currently, is performance tuning.

This patch excludes the NEON support also reviewed due to an outbreak of
batshit insanity in our legal department. That will be committed soon bringing
the changes to precisely what has been approved.

Further reviews would be gratefully received.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174054 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 805 insertions, 0 deletions

diff --git a/lib/Target/AArch64/AArch64InstrInfo.cpp b/lib/Target/AArch64/AArch64InstrInfo.cpp
new file mode 100644
index 0000000000..967960c1e5
--- /dev/null
+++ b/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -0,0 +1,805 @@
+//===- AArch64InstrInfo.cpp - AArch64 Instruction Information -------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the AArch64 implementation of the TargetInstrInfo class.
+//
+//===----------------------------------------------------------------------===//
+
+#include "AArch64.h"
+#include "AArch64InstrInfo.h"
+#include "AArch64MachineFunctionInfo.h"
+#include "AArch64TargetMachine.h"
+#include "MCTargetDesc/AArch64BaseInfo.h"
+#include "MCTargetDesc/AArch64MCTargetDesc.h"
+#include "llvm/CodeGen/MachineConstantPool.h"
+#include "llvm/CodeGen/MachineDominators.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/IR/Function.h"
+#include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/TargetRegistry.h"
+
+#include <algorithm>
+
+#define GET_INSTRINFO_CTOR
+#include "AArch64GenInstrInfo.inc"
+
+using namespace llvm;
+
+AArch64InstrInfo::AArch64InstrInfo(const AArch64Subtarget &STI)
+  : AArch64GenInstrInfo(AArch64::ADJCALLSTACKDOWN, AArch64::ADJCALLSTACKUP),
+    RI(*this, STI), Subtarget(STI) {}
+
+void AArch64InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
+                                   MachineBasicBlock::iterator I, DebugLoc DL,
+                                   unsigned DestReg, unsigned SrcReg,
+                                   bool KillSrc) const {
+  unsigned Opc = 0;
+  unsigned ZeroReg = 0;
+  if (DestReg == AArch64::XSP || SrcReg == AArch64::XSP) {
+    // E.g. ADD xDst, xsp, #0 (, lsl #0)
+    BuildMI(MBB, I, DL, get(AArch64::ADDxxi_lsl0_s), DestReg)
+      .addReg(SrcReg)
+      .addImm(0);
+    return;
+  } else if (DestReg == AArch64::WSP || SrcReg == AArch64::WSP) {
+    // E.g. ADD wDST, wsp, #0 (, lsl #0)
+    BuildMI(MBB, I, DL, get(AArch64::ADDwwi_lsl0_s), DestReg)
+      .addReg(SrcReg)
+      .addImm(0);
+    return;
+  } else if (DestReg == AArch64::NZCV) {
+    assert(AArch64::GPR64RegClass.contains(SrcReg));
+    // E.g. MSR NZCV, xDST
+    BuildMI(MBB, I, DL, get(AArch64::MSRix))
+      .addImm(A64SysReg::NZCV)
+      .addReg(SrcReg);
+  } else if (SrcReg == AArch64::NZCV) {
+    assert(AArch64::GPR64RegClass.contains(DestReg));
+    // E.g. MRS xDST, NZCV
+    BuildMI(MBB, I, DL, get(AArch64::MRSxi), DestReg)
+      .addImm(A64SysReg::NZCV);
+  } else if (AArch64::GPR64RegClass.contains(DestReg)) {
+    assert(AArch64::GPR64RegClass.contains(SrcReg));
+    Opc = AArch64::ORRxxx_lsl;
+    ZeroReg = AArch64::XZR;
+  } else if (AArch64::GPR32RegClass.contains(DestReg)) {
+    assert(AArch64::GPR32RegClass.contains(SrcReg));
+    Opc = AArch64::ORRwww_lsl;
+    ZeroReg = AArch64::WZR;
+  } else if (AArch64::FPR32RegClass.contains(DestReg)) {
+    assert(AArch64::FPR32RegClass.contains(SrcReg));
+    BuildMI(MBB, I, DL, get(AArch64::FMOVss), DestReg)
+      .addReg(SrcReg);
+    return;
+  } else if (AArch64::FPR64RegClass.contains(DestReg)) {
+    assert(AArch64::FPR64RegClass.contains(SrcReg));
+    BuildMI(MBB, I, DL, get(AArch64::FMOVdd), DestReg)
+      .addReg(SrcReg);
+    return;
+  } else if (AArch64::FPR128RegClass.contains(DestReg)) {
+    assert(AArch64::FPR128RegClass.contains(SrcReg));
+
+    // FIXME: there's no good way to do this, at least without NEON:
+    //   + There's no single move instruction for q-registers
+    //   + We can't create a spill slot and use normal STR/LDR because stack
+    //     allocation has already happened
+    //   + We can't go via X-registers with FMOV because register allocation has
+    //     already happened.
+    // This may not be efficient, but at least it works.
+    BuildMI(MBB, I, DL, get(AArch64::LSFP128_PreInd_STR), AArch64::XSP)
+      .addReg(SrcReg)
+      .addReg(AArch64::XSP)
+      .addImm(0x1ff & -16);
+
+    BuildMI(MBB, I, DL, get(AArch64::LSFP128_PostInd_LDR), DestReg)
+      .addReg(AArch64::XSP, RegState::Define)
+      .addReg(AArch64::XSP)
+      .addImm(16);
+    return;
+  } else {
+    llvm_unreachable("Unknown register class in copyPhysReg");
+  }
+
+  // E.g. ORR xDst, xzr, xSrc, lsl #0
+  BuildMI(MBB, I, DL, get(Opc), DestReg)
+    .addReg(ZeroReg)
+    .addReg(SrcReg)
+    .addImm(0);
+}
+
+MachineInstr *
+AArch64InstrInfo::emitFrameIndexDebugValue(MachineFunction &MF, int FrameIx,
+                                           uint64_t Offset, const MDNode *MDPtr,
+                                           DebugLoc DL) const {
+  MachineInstrBuilder MIB = BuildMI(MF, DL, get(AArch64::DBG_VALUE))
+    .addFrameIndex(FrameIx).addImm(0)
+    .addImm(Offset)
+    .addMetadata(MDPtr);
+  return &*MIB;
+}
+
+/// Does the Opcode represent a conditional branch that we can remove and re-add
+/// at the end of a basic block?
+static bool isCondBranch(unsigned Opc) {
+  return Opc == AArch64::Bcc || Opc == AArch64::CBZw || Opc == AArch64::CBZx ||
+         Opc == AArch64::CBNZw || Opc == AArch64::CBNZx ||
+         Opc == AArch64::TBZwii || Opc == AArch64::TBZxii ||
+         Opc == AArch64::TBNZwii || Opc == AArch64::TBNZxii;
+}
+
+/// Takes apart a given conditional branch MachineInstr (see isCondBranch),
+/// setting TBB to the destination basic block and populating the Cond vector
+/// with data necessary to recreate the conditional branch at a later
+/// date. First element will be the opcode, and subsequent ones define the
+/// conditions being branched on in an instruction-specific manner.
+static void classifyCondBranch(MachineInstr *I, MachineBasicBlock *&TBB,
+                               SmallVectorImpl<MachineOperand> &Cond) {
+  switch(I->getOpcode()) {
+  case AArch64::Bcc:
+  case AArch64::CBZw:
+  case AArch64::CBZx:
+  case AArch64::CBNZw:
+  case AArch64::CBNZx:
+    // These instructions just have one predicate operand in position 0 (either
+    // a condition code or a register being compared).
+    Cond.push_back(MachineOperand::CreateImm(I->getOpcode()));
+    Cond.push_back(I->getOperand(0));
+    TBB = I->getOperand(1).getMBB();
+    return;
+  case AArch64::TBZwii:
+  case AArch64::TBZxii:
+  case AArch64::TBNZwii:
+  case AArch64::TBNZxii:
+    // These have two predicate operands: a register and a bit position.
+    Cond.push_back(MachineOperand::CreateImm(I->getOpcode()));
+    Cond.push_back(I->getOperand(0));
+    Cond.push_back(I->getOperand(1));
+    TBB = I->getOperand(2).getMBB();
+    return;
+  default:
+    llvm_unreachable("Unknown conditional branch to classify");
+  }
+}
+
+
+bool
+AArch64InstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB,
+                                MachineBasicBlock *&FBB,
+                                SmallVectorImpl<MachineOperand> &Cond,
+                                bool AllowModify) const {
+  // If the block has no terminators, it just falls into the block after it.
+  MachineBasicBlock::iterator I = MBB.end();
+  if (I == MBB.begin())
+    return false;
+  --I;
+  while (I->isDebugValue()) {
+    if (I == MBB.begin())
+      return false;
+    --I;
+  }
+  if (!isUnpredicatedTerminator(I))
+    return false;
+
+  // Get the last instruction in the block.
+  MachineInstr *LastInst = I;
+
+  // If there is only one terminator instruction, process it.
+  unsigned LastOpc = LastInst->getOpcode();
+  if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
+    if (LastOpc == AArch64::Bimm) {
+      TBB = LastInst->getOperand(0).getMBB();
+      return false;
+    }
+    if (isCondBranch(LastOpc)) {
+      classifyCondBranch(LastInst, TBB, Cond);
+      return false;
+    }
+    return true;  // Can't handle indirect branch.
+  }
+
+  // Get the instruction before it if it is a terminator.
+  MachineInstr *SecondLastInst = I;
+  unsigned SecondLastOpc = SecondLastInst->getOpcode();
+
+  // If AllowModify is true and the block ends with two or more unconditional
+  // branches, delete all but the first unconditional branch.
+  if (AllowModify && LastOpc == AArch64::Bimm) {
+    while (SecondLastOpc == AArch64::Bimm) {
+      LastInst->eraseFromParent();
+      LastInst = SecondLastInst;
+      LastOpc = LastInst->getOpcode();
+      if (I == MBB.begin() || !isUnpredicatedTerminator(--I)) {
+        // Return now the only terminator is an unconditional branch.
+        TBB = LastInst->getOperand(0).getMBB();
+        return false;
+      } else {
+        SecondLastInst = I;
+        SecondLastOpc = SecondLastInst->getOpcode();
+      }
+    }
+  }
+
+  // If there are three terminators, we don't know what sort of block this is.
+  if (SecondLastInst && I != MBB.begin() && isUnpredicatedTerminator(--I))
+    return true;
+
+  // If the block ends with a B and a Bcc, handle it.
+  if (LastOpc == AArch64::Bimm) {
+    if (SecondLastOpc == AArch64::Bcc) {
+      TBB =  SecondLastInst->getOperand(1).getMBB();
+      Cond.push_back(MachineOperand::CreateImm(AArch64::Bcc));
+      Cond.push_back(SecondLastInst->getOperand(0));
+      FBB = LastInst->getOperand(0).getMBB();
+      return false;
+    } else if (isCondBranch(SecondLastOpc)) {
+      classifyCondBranch(SecondLastInst, TBB, Cond);
+      FBB = LastInst->getOperand(0).getMBB();
+      return false;
+    }
+  }
+
+  // If the block ends with two unconditional branches, handle it.  The second
+  // one is not executed, so remove it.
+  if (SecondLastOpc == AArch64::Bimm && LastOpc == AArch64::Bimm) {
+    TBB = SecondLastInst->getOperand(0).getMBB();
+    I = LastInst;
+    if (AllowModify)
+      I->eraseFromParent();
+    return false;
+  }
+
+  // Otherwise, can't handle this.
+  return true;
+}
+
+bool AArch64InstrInfo::ReverseBranchCondition(
+                                  SmallVectorImpl<MachineOperand> &Cond) const {
+  switch (Cond[0].getImm()) {
+  case AArch64::Bcc: {
+    A64CC::CondCodes CC = static_cast<A64CC::CondCodes>(Cond[1].getImm());
+    CC = A64InvertCondCode(CC);
+    Cond[1].setImm(CC);
+    return false;
+  }
+  case AArch64::CBZw:
+    Cond[0].setImm(AArch64::CBNZw);
+    return false;
+  case AArch64::CBZx:
+    Cond[0].setImm(AArch64::CBNZx);
+    return false;
+  case AArch64::CBNZw:
+    Cond[0].setImm(AArch64::CBZw);
+    return false;
+  case AArch64::CBNZx:
+    Cond[0].setImm(AArch64::CBZx);
+    return false;
+  case AArch64::TBZwii:
+    Cond[0].setImm(AArch64::TBNZwii);
+    return false;
+  case AArch64::TBZxii:
+    Cond[0].setImm(AArch64::TBNZxii);
+    return false;
+  case AArch64::TBNZwii:
+    Cond[0].setImm(AArch64::TBZwii);
+    return false;
+  case AArch64::TBNZxii:
+    Cond[0].setImm(AArch64::TBZxii);
+    return false;
+  default:
+    llvm_unreachable("Unknown branch type");
+  }
+}
+
+
+unsigned
+AArch64InstrInfo::InsertBranch(MachineBasicBlock &MBB, MachineBasicBlock *TBB,
+                               MachineBasicBlock *FBB,
+                               const SmallVectorImpl<MachineOperand> &Cond,
+                               DebugLoc DL) const {
+  if (FBB == 0 && Cond.empty()) {
+    BuildMI(&MBB, DL, get(AArch64::Bimm)).addMBB(TBB);
+    return 1;
+  } else if (FBB == 0) {
+    MachineInstrBuilder MIB = BuildMI(&MBB, DL, get(Cond[0].getImm()));
+    for (int i = 1, e = Cond.size(); i != e; ++i)
+      MIB.addOperand(Cond[i]);
+    MIB.addMBB(TBB);
+    return 1;
+  }
+
+  MachineInstrBuilder MIB = BuildMI(&MBB, DL, get(Cond[0].getImm()));
+  for (int i = 1, e = Cond.size(); i != e; ++i)
+    MIB.addOperand(Cond[i]);
+  MIB.addMBB(TBB);
+
+  BuildMI(&MBB, DL, get(AArch64::Bimm)).addMBB(FBB);
+  return 2;
+}
+
+unsigned AArch64InstrInfo::RemoveBranch(MachineBasicBlock &MBB) const {
+  MachineBasicBlock::iterator I = MBB.end();
+  if (I == MBB.begin()) return 0;
+  --I;
+  while (I->isDebugValue()) {
+    if (I == MBB.begin())
+      return 0;
+    --I;
+  }
+  if (I->getOpcode() != AArch64::Bimm && !isCondBranch(I->getOpcode()))
+    return 0;
+
+  // Remove the branch.
+  I->eraseFromParent();
+
+  I = MBB.end();
+
+  if (I == MBB.begin()) return 1;
+  --I;
+  if (!isCondBranch(I->getOpcode()))
+    return 1;
+
+  // Remove the branch.
+  I->eraseFromParent();
+  return 2;
+}
+
+bool
+AArch64InstrInfo::expandPostRAPseudo(MachineBasicBlock::iterator MBBI) const {
+  MachineInstr &MI = *MBBI;
+  MachineBasicBlock &MBB = *MI.getParent();
+
+  unsigned Opcode = MI.getOpcode();
+  switch (Opcode) {
+  case AArch64::TLSDESC_BLRx: {
+    MachineInstr *NewMI =
+      BuildMI(MBB, MBBI, MI.getDebugLoc(), get(AArch64::TLSDESCCALL))
+        .addOperand(MI.getOperand(1));
+    MI.setDesc(get(AArch64::BLRx));
+
+    llvm::finalizeBundle(MBB, NewMI, *++MBBI);
+    return true;
+    }
+  default:
+    return false;
+  }
+
+  return false;
+}
+
+void
+AArch64InstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
+                                      MachineBasicBlock::iterator MBBI,
+                                      unsigned SrcReg, bool isKill,
+                                      int FrameIdx,
+                                      const TargetRegisterClass *RC,
+                                      const TargetRegisterInfo *TRI) const {
+  DebugLoc DL = MBB.findDebugLoc(MBBI);
+  MachineFunction &MF = *MBB.getParent();
+  MachineFrameInfo &MFI = *MF.getFrameInfo();
+  unsigned Align = MFI.getObjectAlignment(FrameIdx);
+
+  MachineMemOperand *MMO
+    = MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FrameIdx),
+                              MachineMemOperand::MOStore,
+                              MFI.getObjectSize(FrameIdx),
+                              Align);
+
+  unsigned StoreOp = 0;
+  if (RC->hasType(MVT::i64) || RC->hasType(MVT::i32)) {
+    switch(RC->getSize()) {
+    case 4: StoreOp = AArch64::LS32_STR; break;
+    case 8: StoreOp = AArch64::LS64_STR; break;
+    default:
+      llvm_unreachable("Unknown size for regclass");
+    }
+  } else {
+    assert((RC->hasType(MVT::f32) || RC->hasType(MVT::f64) ||
+            RC->hasType(MVT::f128))
+           && "Expected integer or floating type for store");
+    switch (RC->getSize()) {
+    case 4: StoreOp = AArch64::LSFP32_STR; break;
+    case 8: StoreOp = AArch64::LSFP64_STR; break;
+    case 16: StoreOp = AArch64::LSFP128_STR; break;
+    default:
+      llvm_unreachable("Unknown size for regclass");
+    }
+  }
+
+  MachineInstrBuilder NewMI = BuildMI(MBB, MBBI, DL, get(StoreOp));
+  NewMI.addReg(SrcReg, getKillRegState(isKill))
+    .addFrameIndex(FrameIdx)
+    .addImm(0)
+    .addMemOperand(MMO);
+
+}
+
+void
+AArch64InstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
+                                       MachineBasicBlock::iterator MBBI,
+                                       unsigned DestReg, int FrameIdx,
+                                       const TargetRegisterClass *RC,
+                                       const TargetRegisterInfo *TRI) const {
+  DebugLoc DL = MBB.findDebugLoc(MBBI);
+  MachineFunction &MF = *MBB.getParent();
+  MachineFrameInfo &MFI = *MF.getFrameInfo();
+  unsigned Align = MFI.getObjectAlignment(FrameIdx);
+
+  MachineMemOperand *MMO
+    = MF.getMachineMemOperand(MachinePointerInfo::getFixedStack(FrameIdx),
+                              MachineMemOperand::MOLoad,
+                              MFI.getObjectSize(FrameIdx),
+                              Align);
+
+  unsigned LoadOp = 0;
+  if (RC->hasType(MVT::i64) || RC->hasType(MVT::i32)) {
+    switch(RC->getSize()) {
+    case 4: LoadOp = AArch64::LS32_LDR; break;
+    case 8: LoadOp = AArch64::LS64_LDR; break;
+    default:
+      llvm_unreachable("Unknown size for regclass");
+    }
+  } else {
+    assert((RC->hasType(MVT::f32) || RC->hasType(MVT::f64)
+            || RC->hasType(MVT::f128))
+           && "Expected integer or floating type for store");
+    switch (RC->getSize()) {
+    case 4: LoadOp = AArch64::LSFP32_LDR; break;
+    case 8: LoadOp = AArch64::LSFP64_LDR; break;
+    case 16: LoadOp = AArch64::LSFP128_LDR; break;
+    default:
+      llvm_unreachable("Unknown size for regclass");
+    }
+  }
+
+  MachineInstrBuilder NewMI = BuildMI(MBB, MBBI, DL, get(LoadOp), DestReg);
+  NewMI.addFrameIndex(FrameIdx)
+       .addImm(0)
+       .addMemOperand(MMO);
+}
+
+unsigned AArch64InstrInfo::estimateRSStackLimit(MachineFunction &MF) const {
+  unsigned Limit = (1 << 16) - 1;
+  for (MachineFunction::iterator BB = MF.begin(),E = MF.end(); BB != E; ++BB) {
+    for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end();
+         I != E; ++I) {
+      for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
+        if (!I->getOperand(i).isFI()) continue;
+
+        // When using ADDxxi_lsl0_s to get the address of a stack object, 0xfff
+        // is the largest offset guaranteed to fit in the immediate offset.
+        if (I->getOpcode() == AArch64::ADDxxi_lsl0_s) {
+          Limit = std::min(Limit, 0xfffu);
+          break;
+        }
+
+        int AccessScale, MinOffset, MaxOffset;
+        getAddressConstraints(*I, AccessScale, MinOffset, MaxOffset);
+        Limit = std::min(Limit, static_cast<unsigned>(MaxOffset));
+
+        break; // At most one FI per instruction
+      }
+    }
+  }
+
+  return Limit;
+}
+void AArch64InstrInfo::getAddressConstraints(const MachineInstr &MI,
+                                             int &AccessScale, int &MinOffset,
+                                             int &MaxOffset) const {
+  switch (MI.getOpcode()) {
+  default: llvm_unreachable("Unkown load/store kind");
+  case TargetOpcode::DBG_VALUE:
+    AccessScale = 1;
+    MinOffset = INT_MIN;
+    MaxOffset = INT_MAX;
+    return;
+  case AArch64::LS8_LDR: case AArch64::LS8_STR:
+  case AArch64::LSFP8_LDR: case AArch64::LSFP8_STR:
+  case AArch64::LDRSBw:
+  case AArch64::LDRSBx:
+    AccessScale = 1;
+    MinOffset = 0;
+    MaxOffset = 0xfff;
+    return;
+  case AArch64::LS16_LDR: case AArch64::LS16_STR:
+  case AArch64::LSFP16_LDR: case AArch64::LSFP16_STR:
+  case AArch64::LDRSHw:
+  case AArch64::LDRSHx:
+    AccessScale = 2;
+    MinOffset = 0;
+    MaxOffset = 0xfff * AccessScale;
+    return;
+  case AArch64::LS32_LDR:  case AArch64::LS32_STR:
+  case AArch64::LSFP32_LDR: case AArch64::LSFP32_STR:
+  case AArch64::LDRSWx:
+  case AArch64::LDPSWx:
+    AccessScale = 4;
+    MinOffset = 0;
+    MaxOffset = 0xfff * AccessScale;
+    return;
+  case AArch64::LS64_LDR: case AArch64::LS64_STR:
+  case AArch64::LSFP64_LDR: case AArch64::LSFP64_STR:
+  case AArch64::PRFM:
+    AccessScale = 8;
+    MinOffset = 0;
+    MaxOffset = 0xfff * AccessScale;
+    return;
+  case AArch64::LSFP128_LDR: case AArch64::LSFP128_STR:
+    AccessScale = 16;
+    MinOffset = 0;
+    MaxOffset = 0xfff * AccessScale;
+    return;
+  case AArch64::LSPair32_LDR: case AArch64::LSPair32_STR:
+  case AArch64::LSFPPair32_LDR: case AArch64::LSFPPair32_STR:
+    AccessScale = 4;
+    MinOffset = -0x40 * AccessScale;
+    MaxOffset = 0x3f * AccessScale;
+    return;
+  case AArch64::LSPair64_LDR: case AArch64::LSPair64_STR:
+  case AArch64::LSFPPair64_LDR: case AArch64::LSFPPair64_STR:
+    AccessScale = 8;
+    MinOffset = -0x40 * AccessScale;
+    MaxOffset = 0x3f * AccessScale;
+    return;
+  case AArch64::LSFPPair128_LDR: case AArch64::LSFPPair128_STR:
+    AccessScale = 16;
+    MinOffset = -0x40 * AccessScale;
+    MaxOffset = 0x3f * AccessScale;
+    return;
+  }
+}
+
+unsigned AArch64InstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
+  const MCInstrDesc &MCID = MI.getDesc();
+  const MachineBasicBlock &MBB = *MI.getParent();
+  const MachineFunction &MF = *MBB.getParent();
+  const MCAsmInfo &MAI = *MF.getTarget().getMCAsmInfo();
+
+  if (MCID.getSize())
+    return MCID.getSize();
+
+  if (MI.getOpcode() == AArch64::INLINEASM)
+    return getInlineAsmLength(MI.getOperand(0).getSymbolName(), MAI);
+
+  if (MI.isLabel())
+    return 0;
+
+  switch (MI.getOpcode()) {
+  case TargetOpcode::BUNDLE:
+    return getInstBundleLength(MI);
+  case TargetOpcode::IMPLICIT_DEF:
+  case TargetOpcode::KILL:
+  case TargetOpcode::PROLOG_LABEL:
+  case TargetOpcode::EH_LABEL:
+  case TargetOpcode::DBG_VALUE:
+    return 0;
+  case AArch64::CONSTPOOL_ENTRY:
+    return MI.getOperand(2).getImm();
+  case AArch64::TLSDESCCALL:
+    return 0;
+  default:
+    llvm_unreachable("Unknown instruction class");
+  }
+}
+
+unsigned AArch64InstrInfo::getInstBundleLength(const MachineInstr &MI) const {
+  unsigned Size = 0;
+  MachineBasicBlock::const_instr_iterator I = MI;
+  MachineBasicBlock::const_instr_iterator E = MI.getParent()->instr_end();
+  while (++I != E && I->isInsideBundle()) {
+    assert(!I->isBundle() && "No nested bundle!");
+    Size += getInstSizeInBytes(*I);
+  }
+  return Size;
+}
+
+bool llvm::rewriteA64FrameIndex(MachineInstr &MI, unsigned FrameRegIdx,
+                                unsigned FrameReg, int &Offset,
+                                const AArch64InstrInfo &TII) {
+  MachineBasicBlock &MBB = *MI.getParent();
+  MachineFunction &MF = *MBB.getParent();
+  MachineFrameInfo &MFI = *MF.getFrameInfo();
+
+  MFI.getObjectOffset(FrameRegIdx);
+  llvm_unreachable("Unimplemented rewriteFrameIndex");
+}
+
+void llvm::emitRegUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator MBBI,
+                         DebugLoc dl, const TargetInstrInfo &TII,
+                         unsigned DstReg, unsigned SrcReg, unsigned ScratchReg,
+                         int64_t NumBytes, MachineInstr::MIFlag MIFlags) {
+  if (NumBytes == 0 && DstReg == SrcReg)
+    return;
+  else if (abs(NumBytes) & ~0xffffff) {
+    // Generically, we have to materialize the offset into a temporary register
+    // and subtract it. There are a couple of ways this could be done, for now
+    // we'll go for a literal-pool load.
+    MachineFunction &MF = *MBB.getParent();
+    MachineConstantPool *MCP = MF.getConstantPool();
+    const Constant *C
+      = ConstantInt::get(Type::getInt64Ty(MF.getFunction()->getContext()),
+                         abs(NumBytes));
+    unsigned CPI = MCP->getConstantPoolIndex(C, 8);
+
+    // LDR xTMP, .LITPOOL
+    BuildMI(MBB, MBBI, dl, TII.get(AArch64::LDRx_lit), ScratchReg)
+      .addConstantPoolIndex(CPI)
+      .setMIFlag(MIFlags);
+
+    // ADD DST, SRC, xTMP (, lsl #0)
+    unsigned AddOp = NumBytes > 0 ? AArch64::ADDxxx_uxtx : AArch64::SUBxxx_uxtx;
+    BuildMI(MBB, MBBI, dl, TII.get(AddOp), DstReg)
+      .addReg(SrcReg, RegState::Kill)
+      .addReg(ScratchReg, RegState::Kill)
+      .addImm(0)
+      .setMIFlag(MIFlags);
+    return;
+  }
+
+  // Now we know that the adjustment can be done in at most two add/sub
+  // (immediate) instructions, which is always more efficient than a
+  // literal-pool load, or even a hypothetical movz/movk/add sequence
+
+  // Decide whether we're doing addition or subtraction
+  unsigned LowOp, HighOp;
+  if (NumBytes >= 0) {
+    LowOp = AArch64::ADDxxi_lsl0_s;
+    HighOp = AArch64::ADDxxi_lsl12_s;
+  } else {
+    LowOp = AArch64::SUBxxi_lsl0_s;
+    HighOp = AArch64::SUBxxi_lsl12_s;
+    NumBytes = abs(NumBytes);
+  }
+
+  // If we're here, at the very least a move needs to be produced, which just
+  // happens to be materializable by an ADD.
+  if ((NumBytes & 0xfff) || NumBytes == 0) {
+    BuildMI(MBB, MBBI, dl, TII.get(LowOp), DstReg)
+      .addReg(SrcReg, RegState::Kill)
+      .addImm(NumBytes & 0xfff)
+      .setMIFlag(MIFlags);
+
+    // Next update should use the register we've just defined.
+    SrcReg = DstReg;
+  }
+
+  if (NumBytes & 0xfff000) {
+    BuildMI(MBB, MBBI, dl, TII.get(HighOp), DstReg)
+      .addReg(SrcReg, RegState::Kill)
+      .addImm(NumBytes >> 12)
+      .setMIFlag(MIFlags);
+  }
+}
+
+void llvm::emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
+                        DebugLoc dl, const TargetInstrInfo &TII,
+                        unsigned ScratchReg, int64_t NumBytes,
+                        MachineInstr::MIFlag MIFlags) {
+  emitRegUpdate(MBB, MI, dl, TII, AArch64::XSP, AArch64::XSP, AArch64::X16,
+                NumBytes, MIFlags);
+}
+
+
+namespace {
+  struct LDTLSCleanup : public MachineFunctionPass {
+    static char ID;
+    LDTLSCleanup() : MachineFunctionPass(ID) {}
+
+    virtual bool runOnMachineFunction(MachineFunction &MF) {
+      AArch64MachineFunctionInfo* MFI = MF.getInfo<AArch64MachineFunctionInfo>();
+      if (MFI->getNumLocalDynamicTLSAccesses() < 2) {
+        // No point folding accesses if there isn't at least two.
+        return false;
+      }
+
+      MachineDominatorTree *DT = &getAnalysis<MachineDominatorTree>();
+      return VisitNode(DT->getRootNode(), 0);
+    }
+
+    // Visit the dominator subtree rooted at Node in pre-order.
+    // If TLSBaseAddrReg is non-null, then use that to replace any
+    // TLS_base_addr instructions. Otherwise, create the register
+    // when the first such instruction is seen, and then use it
+    // as we encounter more instructions.
+    bool VisitNode(MachineDomTreeNode *Node, unsigned TLSBaseAddrReg) {
+      MachineBasicBlock *BB = Node->getBlock();
+      bool Changed = false;
+
+      // Traverse the current block.
+      for (MachineBasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;
+           ++I) {
+        switch (I->getOpcode()) {
+        case AArch64::TLSDESC_BLRx:
+          // Make sure it's a local dynamic access.
+          if (!I->getOperand(1).isSymbol() ||
+              strcmp(I->getOperand(1).getSymbolName(), "_TLS_MODULE_BASE_"))
+            break;
+
+          if (TLSBaseAddrReg)
+            I = ReplaceTLSBaseAddrCall(I, TLSBaseAddrReg);
+          else
+            I = SetRegister(I, &TLSBaseAddrReg);
+          Changed = true;
+          break;
+        default:
+          break;
+        }
+      }
+
+      // Visit the children of this block in the dominator tree.
+      for (MachineDomTreeNode::iterator I = Node->begin(), E = Node->end();
+           I != E; ++I) {
+        Changed |= VisitNode(*I, TLSBaseAddrReg);
+      }
+
+      return Changed;
+    }
+
+    // Replace the TLS_base_addr instruction I with a copy from
+    // TLSBaseAddrReg, returning the new instruction.
+    MachineInstr *ReplaceTLSBaseAddrCall(MachineInstr *I,
+                                         unsigned TLSBaseAddrReg) {
+      MachineFunction *MF = I->getParent()->getParent();
+      const AArch64TargetMachine *TM =
+          static_cast<const AArch64TargetMachine *>(&MF->getTarget());
+      const AArch64InstrInfo *TII = TM->getInstrInfo();
+
+      // Insert a Copy from TLSBaseAddrReg to x0, which is where the rest of the
+      // code sequence assumes the address will be.
+      MachineInstr *Copy = BuildMI(*I->getParent(), I, I->getDebugLoc(),
+                                   TII->get(TargetOpcode::COPY),
+                                   AArch64::X0)
+        .addReg(TLSBaseAddrReg);
+
+      // Erase the TLS_base_addr instruction.
+      I->eraseFromParent();
+
+      return Copy;
+    }
+
+    // Create a virtal register in *TLSBaseAddrReg, and populate it by
+    // inserting a copy instruction after I. Returns the new instruction.
+    MachineInstr *SetRegister(MachineInstr *I, unsigned *TLSBaseAddrReg) {
+      MachineFunction *MF = I->getParent()->getParent();
+      const AArch64TargetMachine *TM =
+          static_cast<const AArch64TargetMachine *>(&MF->getTarget());
+      const AArch64InstrInfo *TII = TM->getInstrInfo();
+
+      // Create a virtual register for the TLS base address.
+      MachineRegisterInfo &RegInfo = MF->getRegInfo();
+      *TLSBaseAddrReg = RegInfo.createVirtualRegister(&AArch64::GPR64RegClass);
+
+      // Insert a copy from X0 to TLSBaseAddrReg for later.
+      MachineInstr *Next = I->getNextNode();
+      MachineInstr *Copy = BuildMI(*I->getParent(), Next, I->getDebugLoc(),
+                                   TII->get(TargetOpcode::COPY),
+                                   *TLSBaseAddrReg)
+        .addReg(AArch64::X0);
+
+      return Copy;
+    }
+
+    virtual const char *getPassName() const {
+      return "Local Dynamic TLS Access Clean-up";
+    }
+
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+      AU.addRequired<MachineDominatorTree>();
+      MachineFunctionPass::getAnalysisUsage(AU);
+    }
+  };
+}
+
+char LDTLSCleanup::ID = 0;
+FunctionPass*
+llvm::createAArch64CleanupLocalDynamicTLSPass() { return new LDTLSCleanup(); }