Bring in fixes for Cortex-A53 errata + build updates.

Bug: 18034609

Change-Id: I2cf0094eb9df801a84274ff29018431d75da89dd

16 files changed, 1035 insertions, 11 deletions

diff --git a/lib/CodeGen/CriticalAntiDepBreaker.cpp b/lib/CodeGen/CriticalAntiDepBreaker.cpp
index d3ffcc7..d2231ec 100644
--- a/lib/CodeGen/CriticalAntiDepBreaker.cpp
+++ b/lib/CodeGen/CriticalAntiDepBreaker.cpp
@@ -94,7 +94,14 @@ void CriticalAntiDepBreaker::FinishBlock() {
 
 void CriticalAntiDepBreaker::Observe(MachineInstr *MI, unsigned Count,
                                      unsigned InsertPosIndex) {
-  if (MI->isDebugValue())
+  // Kill instructions can define registers but are really nops, and there might
+  // be a real definition earlier that needs to be paired with uses dominated by
+  // this kill.
+
+  // FIXME: It may be possible to remove the isKill() restriction once PR18663
+  // has been properly fixed. There can be value in processing kills as seen in
+  // the AggressiveAntiDepBreaker class.
+  if (MI->isDebugValue() || MI->isKill())
     return;
   assert(Count < InsertPosIndex && "Instruction index out of expected range!");
 
@@ -237,6 +244,7 @@ void CriticalAntiDepBreaker::ScanInstruction(MachineInstr *MI,
   // Update liveness.
   // Proceeding upwards, registers that are defed but not used in this
   // instruction are now dead.
+  assert(!MI->isKill() && "Attempting to scan a kill instruction");
 
   if (!TII->isPredicated(MI)) {
     // Predicated defs are modeled as read + write, i.e. similar to two
@@ -527,7 +535,14 @@ BreakAntiDependencies(const std::vector<SUnit>& SUnits,
   unsigned Count = InsertPosIndex - 1;
   for (MachineBasicBlock::iterator I = End, E = Begin; I != E; --Count) {
     MachineInstr *MI = --I;
-    if (MI->isDebugValue())
+    // Kill instructions can define registers but are really nops, and there
+    // might be a real definition earlier that needs to be paired with uses
+    // dominated by this kill.
+    
+    // FIXME: It may be possible to remove the isKill() restriction once PR18663
+    // has been properly fixed. There can be value in processing kills as seen
+    // in the AggressiveAntiDepBreaker class.
+    if (MI->isDebugValue() || MI->isKill())
       continue;
 
     // Check if this instruction has a dependence on the critical path that
diff --git a/lib/CodeGen/LiveRangeEdit.cpp b/lib/CodeGen/LiveRangeEdit.cpp
index 431241f..c27d630 100644
--- a/lib/CodeGen/LiveRangeEdit.cpp
+++ b/lib/CodeGen/LiveRangeEdit.cpp
@@ -135,7 +135,7 @@ bool LiveRangeEdit::canRematerializeAt(Remat &RM,
   }
 
   // If only cheap remats were requested, bail out early.
-  if (cheapAsAMove && !RM.OrigMI->isAsCheapAsAMove())
+  if (cheapAsAMove && !TII.isAsCheapAsAMove(RM.OrigMI))
     return false;
 
   // Verify that all used registers are available with the same values.
diff --git a/lib/CodeGen/MachineCSE.cpp b/lib/CodeGen/MachineCSE.cpp
index 7da439c..c2ab76e 100644
--- a/lib/CodeGen/MachineCSE.cpp
+++ b/lib/CodeGen/MachineCSE.cpp
@@ -380,7 +380,7 @@ bool MachineCSE::isProfitableToCSE(unsigned CSReg, unsigned Reg,
   // Heuristics #1: Don't CSE "cheap" computation if the def is not local or in
   // an immediate predecessor. We don't want to increase register pressure and
   // end up causing other computation to be spilled.
-  if (MI->isAsCheapAsAMove()) {
+  if (TII->isAsCheapAsAMove(MI)) {
     MachineBasicBlock *CSBB = CSMI->getParent();
     MachineBasicBlock *BB = MI->getParent();
     if (CSBB != BB && !CSBB->isSuccessor(BB))
diff --git a/lib/CodeGen/MachineLICM.cpp b/lib/CodeGen/MachineLICM.cpp
index 68d2efd..94cdab5 100644
--- a/lib/CodeGen/MachineLICM.cpp
+++ b/lib/CodeGen/MachineLICM.cpp
@@ -1039,7 +1039,7 @@ bool MachineLICM::HasHighOperandLatency(MachineInstr &MI,
 /// IsCheapInstruction - Return true if the instruction is marked "cheap" or
 /// the operand latency between its def and a use is one or less.
 bool MachineLICM::IsCheapInstruction(MachineInstr &MI) const {
-  if (MI.isAsCheapAsAMove() || MI.isCopyLike())
+  if (TII->isAsCheapAsAMove(&MI) || MI.isCopyLike())
     return true;
   if (!InstrItins || InstrItins->isEmpty())
     return false;
diff --git a/lib/CodeGen/MachineSink.cpp b/lib/CodeGen/MachineSink.cpp
index f44e4d1..0ae495c 100644
--- a/lib/CodeGen/MachineSink.cpp
+++ b/lib/CodeGen/MachineSink.cpp
@@ -292,7 +292,7 @@ bool MachineSinking::isWorthBreakingCriticalEdge(MachineInstr *MI,
   if (!CEBCandidates.insert(std::make_pair(From, To)))
     return true;
 
-  if (!MI->isCopy() && !MI->isAsCheapAsAMove())
+  if (!MI->isCopy() && !TII->isAsCheapAsAMove(MI))
     return true;
 
   // MI is cheap, we probably don't want to break the critical edge for it.
diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp
index 5aaeb87..65b0528 100644
--- a/lib/CodeGen/RegisterCoalescer.cpp
+++ b/lib/CodeGen/RegisterCoalescer.cpp
@@ -751,7 +751,7 @@ bool RegisterCoalescer::reMaterializeTrivialDef(CoalescerPair &CP,
     IsDefCopy = true;
     return false;
   }
-  if (!DefMI->isAsCheapAsAMove())
+  if (!TII->isAsCheapAsAMove(DefMI))
     return false;
   if (!TII->isTriviallyReMaterializable(DefMI, AA))
     return false;
diff --git a/lib/Target/AArch64/AArch64.h b/lib/Target/AArch64/AArch64.h
index 1c022aa..7b52e55 100644
--- a/lib/Target/AArch64/AArch64.h
+++ b/lib/Target/AArch64/AArch64.h
@@ -37,6 +37,8 @@ FunctionPass *createAArch64ExpandPseudoPass();
 FunctionPass *createAArch64LoadStoreOptimizationPass();
 ModulePass *createAArch64PromoteConstantPass();
 FunctionPass *createAArch64AddressTypePromotionPass();
+FunctionPass *createAArch64A57FPLoadBalancing();
+FunctionPass *createAArch64A53Fix835769();
 /// \brief Creates an ARM-specific Target Transformation Info pass.
 ImmutablePass *
 createAArch64TargetTransformInfoPass(const AArch64TargetMachine *TM);
diff --git a/lib/Target/AArch64/AArch64A53Fix835769.cpp b/lib/Target/AArch64/AArch64A53Fix835769.cpp
new file mode 100644
index 0000000..852a635
--- /dev/null
+++ b/lib/Target/AArch64/AArch64A53Fix835769.cpp
@@ -0,0 +1,240 @@
+//===-- AArch64A53Fix835769.cpp -------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// This pass changes code to work around Cortex-A53 erratum 835769.
+// It works around it by inserting a nop instruction in code sequences that
+// in some circumstances may trigger the erratum.
+// It inserts a nop instruction between a sequence of the following 2 classes
+// of instructions:
+// instr 1: mem-instr (including loads, stores and prefetches).
+// instr 2: non-SIMD integer multiply-accumulate writing 64-bit X registers.
+//===----------------------------------------------------------------------===//
+
+#include "AArch64.h"
+#include "AArch64InstrInfo.h"
+#include "AArch64Subtarget.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+
+using namespace llvm;
+
+#define DEBUG_TYPE "aarch64-fix-cortex-a53-835769"
+
+STATISTIC(NumNopsAdded, "Number of Nops added to work around erratum 835769");
+
+//===----------------------------------------------------------------------===//
+// Helper functions
+
+// Is the instruction a match for the instruction that comes first in the
+// sequence of instructions that can trigger the erratum?
+static bool isFirstInstructionInSequence(MachineInstr *MI) {
+  // Must return true if this instruction is a load, a store or a prefetch.
+  switch (MI->getOpcode()) {
+  case AArch64::PRFMl:
+  case AArch64::PRFMroW:
+  case AArch64::PRFMroX:
+  case AArch64::PRFMui:
+  case AArch64::PRFUMi:
+    return true;
+  default:
+    return (MI->mayLoad() || MI->mayStore());
+  }
+}
+
+// Is the instruction a match for the instruction that comes second in the
+// sequence that can trigger the erratum?
+static bool isSecondInstructionInSequence(MachineInstr *MI) {
+  // Must return true for non-SIMD integer multiply-accumulates, writing
+  // to a 64-bit register.
+  switch (MI->getOpcode()) {
+  // Erratum cannot be triggered when the destination register is 32 bits,
+  // therefore only include the following.
+  case AArch64::MSUBXrrr:
+  case AArch64::MADDXrrr:
+  case AArch64::SMADDLrrr:
+  case AArch64::SMSUBLrrr:
+  case AArch64::UMADDLrrr:
+  case AArch64::UMSUBLrrr:
+    // Erratum can only be triggered by multiply-adds, not by regular
+    // non-accumulating multiplies, i.e. when Ra=XZR='11111'
+    return MI->getOperand(3).getReg() != AArch64::XZR;
+  default:
+    return false;
+  }
+}
+
+
+//===----------------------------------------------------------------------===//
+
+namespace {
+class AArch64A53Fix835769 : public MachineFunctionPass {
+  const AArch64InstrInfo *TII;
+
+public:
+  static char ID;
+  explicit AArch64A53Fix835769() : MachineFunctionPass(ID) {}
+
+  bool runOnMachineFunction(MachineFunction &F) override;
+
+  const char *getPassName() const override {
+    return "Workaround A53 erratum 835769 pass";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+private:
+  bool runOnBasicBlock(MachineBasicBlock &MBB);
+};
+char AArch64A53Fix835769::ID = 0;
+
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
+
+bool
+AArch64A53Fix835769::runOnMachineFunction(MachineFunction &F) {
+  const TargetMachine &TM = F.getTarget();
+
+  bool Changed = false;
+  DEBUG(dbgs() << "***** AArch64A53Fix835769 *****\n");
+
+  TII = TM.getSubtarget<AArch64Subtarget>().getInstrInfo();
+
+  for (auto &MBB : F) {
+    Changed |= runOnBasicBlock(MBB);
+  }
+
+  return Changed;
+}
+
+// Return the block that was fallen through to get to MBB, if any,
+// otherwise nullptr.
+static MachineBasicBlock *getBBFallenThrough(MachineBasicBlock *MBB,
+                                             const TargetInstrInfo *TII) {
+  // Get the previous machine basic block in the function.
+  MachineFunction::iterator MBBI = *MBB;
+
+  // Can't go off top of function.
+  if (MBBI == MBB->getParent()->begin())
+    return nullptr;
+
+  MachineBasicBlock *TBB = nullptr, *FBB = nullptr;
+  SmallVector<MachineOperand, 2> Cond;
+
+  MachineBasicBlock *PrevBB = std::prev(MBBI);
+  for (MachineBasicBlock *S : MBB->predecessors())
+    if (S == PrevBB && !TII->AnalyzeBranch(*PrevBB, TBB, FBB, Cond) &&
+        !TBB && !FBB)
+      return S;
+
+  return nullptr;
+}
+
+// Iterate through fallen through blocks trying to find a previous non-pseudo if
+// there is one, otherwise return nullptr. Only look for instructions in
+// previous blocks, not the current block, since we only use this to look at
+// previous blocks.
+static MachineInstr *getLastNonPseudo(MachineBasicBlock &MBB,
+                                      const TargetInstrInfo *TII) {
+  MachineBasicBlock *FMBB = &MBB;
+
+  // If there is no non-pseudo in the current block, loop back around and try
+  // the previous block (if there is one).
+  while ((FMBB = getBBFallenThrough(FMBB, TII))) {
+    for (auto I = FMBB->rbegin(), E = FMBB->rend(); I != E; ++I) {
+      if (!I->isPseudo())
+        return &*I;
+    }
+  }
+
+  // There was no previous non-pseudo in the fallen through blocks
+  return nullptr;
+}
+
+static void insertNopBeforeInstruction(MachineBasicBlock &MBB, MachineInstr* MI,
+                                       const TargetInstrInfo *TII) {
+  // If we are the first instruction of the block, put the NOP at the end of
+  // the previous fallthrough block
+  if (MI == &MBB.front()) {
+    MachineInstr *I = getLastNonPseudo(MBB, TII);
+    assert(I && "Expected instruction");
+    DebugLoc DL = I->getDebugLoc();
+    BuildMI(I->getParent(), DL, TII->get(AArch64::HINT)).addImm(0);
+  }
+  else {
+    DebugLoc DL = MI->getDebugLoc();
+    BuildMI(MBB, MI, DL, TII->get(AArch64::HINT)).addImm(0);
+  }
+
+  ++NumNopsAdded;
+}
+
+bool
+AArch64A53Fix835769::runOnBasicBlock(MachineBasicBlock &MBB) {
+  bool Changed = false;
+  DEBUG(dbgs() << "Running on MBB: " << MBB << " - scanning instructions...\n");
+
+  // First, scan the basic block, looking for a sequence of 2 instructions
+  // that match the conditions under which the erratum may trigger.
+
+  // List of terminating instructions in matching sequences
+  std::vector<MachineInstr*> Sequences;
+  unsigned Idx = 0;
+  MachineInstr *PrevInstr = nullptr;
+
+  // Try and find the last non-pseudo instruction in any fallen through blocks,
+  // if there isn't one, then we use nullptr to represent that.
+  PrevInstr = getLastNonPseudo(MBB, TII);
+
+  for (auto &MI : MBB) {
+    MachineInstr *CurrInstr = &MI;
+    DEBUG(dbgs() << "  Examining: " << MI);
+    if (PrevInstr) {
+      DEBUG(dbgs() << "    PrevInstr: " << *PrevInstr
+                   << "    CurrInstr: " << *CurrInstr
+                   << "    isFirstInstructionInSequence(PrevInstr): "
+                   << isFirstInstructionInSequence(PrevInstr) << "\n"
+                   << "    isSecondInstructionInSequence(CurrInstr): "
+                   << isSecondInstructionInSequence(CurrInstr) << "\n");
+      if (isFirstInstructionInSequence(PrevInstr) &&
+          isSecondInstructionInSequence(CurrInstr)) {
+        DEBUG(dbgs() << "   ** pattern found at Idx " << Idx << "!\n");
+        Sequences.push_back(CurrInstr);
+      }
+    }
+    if (!CurrInstr->isPseudo())
+      PrevInstr = CurrInstr;
+    ++Idx;
+  }
+
+  DEBUG(dbgs() << "Scan complete, "<< Sequences.size()
+               << " occurences of pattern found.\n");
+
+  // Then update the basic block, inserting nops between the detected sequences.
+  for (auto &MI : Sequences) {
+    Changed = true;
+    insertNopBeforeInstruction(MBB, MI, TII);
+  }
+
+  return Changed;
+}
+
+// Factory function used by AArch64TargetMachine to add the pass to
+// the passmanager.
+FunctionPass *llvm::createAArch64A53Fix835769() {
+  return new AArch64A53Fix835769();
+}
diff --git a/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
new file mode 100644
index 0000000..195a48e
--- /dev/null
+++ b/lib/Target/AArch64/AArch64A57FPLoadBalancing.cpp
@@ -0,0 +1,694 @@
+//===-- AArch64A57FPLoadBalancing.cpp - Balance FP ops statically on A57---===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+// For best-case performance on Cortex-A57, we should try to use a balanced
+// mix of odd and even D-registers when performing a critical sequence of
+// independent, non-quadword FP/ASIMD floating-point multiply or
+// multiply-accumulate operations.
+//
+// This pass attempts to detect situations where the register allocation may
+// adversely affect this load balancing and to change the registers used so as
+// to better utilize the CPU.
+//
+// Ideally we'd just take each multiply or multiply-accumulate in turn and
+// allocate it alternating even or odd registers. However, multiply-accumulates
+// are most efficiently performed in the same functional unit as their
+// accumulation operand. Therefore this pass tries to find maximal sequences
+// ("Chains") of multiply-accumulates linked via their accumulation operand,
+// and assign them all the same "color" (oddness/evenness).
+//
+// This optimization affects S-register and D-register floating point
+// multiplies and FMADD/FMAs, as well as vector (floating point only) muls and
+// FMADD/FMA. Q register instructions (and 128-bit vector instructions) are
+// not affected.
+//===----------------------------------------------------------------------===//
+
+#include "AArch64.h"
+#include "AArch64InstrInfo.h"
+#include "AArch64Subtarget.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/EquivalenceClasses.h"
+#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstr.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineRegisterInfo.h"
+#include "llvm/CodeGen/RegisterScavenging.h"
+#include "llvm/CodeGen/RegisterClassInfo.h"
+#include "llvm/Support/CommandLine.h"
+#include "llvm/Support/Debug.h"
+#include "llvm/Support/raw_ostream.h"
+#include <list>
+using namespace llvm;
+
+#define DEBUG_TYPE "aarch64-a57-fp-load-balancing"
+
+// Enforce the algorithm to use the scavenged register even when the original
+// destination register is the correct color. Used for testing.
+static cl::opt<bool>
+TransformAll("aarch64-a57-fp-load-balancing-force-all",
+             cl::desc("Always modify dest registers regardless of color"),
+             cl::init(false), cl::Hidden);
+
+// Never use the balance information obtained from chains - return a specific
+// color always. Used for testing.
+static cl::opt<unsigned>
+OverrideBalance("aarch64-a57-fp-load-balancing-override",
+              cl::desc("Ignore balance information, always return "
+                       "(1: Even, 2: Odd)."),
+              cl::init(0), cl::Hidden);
+
+//===----------------------------------------------------------------------===//
+// Helper functions
+
+// Is the instruction a type of multiply on 64-bit (or 32-bit) FPRs?
+static bool isMul(MachineInstr *MI) {
+  switch (MI->getOpcode()) {
+  case AArch64::FMULSrr:
+  case AArch64::FNMULSrr:
+  case AArch64::FMULDrr:
+  case AArch64::FNMULDrr:
+
+  case AArch64::FMULv2f32:
+    return true;
+  default:
+    return false;
+  }
+}
+
+// Is the instruction a type of FP multiply-accumulate on 64-bit (or 32-bit) FPRs?
+static bool isMla(MachineInstr *MI) {
+  switch (MI->getOpcode()) {
+  case AArch64::FMSUBSrrr:
+  case AArch64::FMADDSrrr:
+  case AArch64::FNMSUBSrrr:
+  case AArch64::FNMADDSrrr:
+  case AArch64::FMSUBDrrr:
+  case AArch64::FMADDDrrr:
+  case AArch64::FNMSUBDrrr:
+  case AArch64::FNMADDDrrr:
+
+  case AArch64::FMLAv2f32:
+  case AArch64::FMLSv2f32:
+    return true;
+  default:
+    return false;
+  }
+}
+
+//===----------------------------------------------------------------------===//
+
+namespace {
+/// A "color", which is either even or odd. Yes, these aren't really colors
+/// but the algorithm is conceptually doing two-color graph coloring.
+enum class Color { Even, Odd };
+static const char *ColorNames[2] = { "Even", "Odd" };
+
+class Chain;
+
+class AArch64A57FPLoadBalancing : public MachineFunctionPass {
+  const AArch64InstrInfo *TII;
+  MachineRegisterInfo *MRI;
+  const TargetRegisterInfo *TRI;
+  RegisterClassInfo RCI;
+
+public:
+  static char ID;
+  explicit AArch64A57FPLoadBalancing() : MachineFunctionPass(ID) {}
+
+  bool runOnMachineFunction(MachineFunction &F) override;
+
+  const char *getPassName() const override {
+    return "A57 FP Anti-dependency breaker";
+  }
+
+  void getAnalysisUsage(AnalysisUsage &AU) const override {
+    AU.setPreservesCFG();
+    MachineFunctionPass::getAnalysisUsage(AU);
+  }
+
+private:
+  bool runOnBasicBlock(MachineBasicBlock &MBB);
+  bool colorChainSet(std::vector<Chain*> GV, MachineBasicBlock &MBB,
+                     int &Balance);
+  bool colorChain(Chain *G, Color C, MachineBasicBlock &MBB);
+  int scavengeRegister(Chain *G, Color C, MachineBasicBlock &MBB);
+  void scanInstruction(MachineInstr *MI, unsigned Idx,
+                       std::map<unsigned, Chain*> &Chains,
+                       std::set<Chain*> &ChainSet);
+  void maybeKillChain(MachineOperand &MO, unsigned Idx,
+                      std::map<unsigned, Chain*> &RegChains);
+  Color getColor(unsigned Register);
+  Chain *getAndEraseNext(Color PreferredColor, std::vector<Chain*> &L);
+};
+char AArch64A57FPLoadBalancing::ID = 0;
+
+/// A Chain is a sequence of instructions that are linked together by 
+/// an accumulation operand. For example:
+///
+///   fmul d0<def>, ?
+///   fmla d1<def>, ?, ?, d0<kill>
+///   fmla d2<def>, ?, ?, d1<kill>
+///
+/// There may be other instructions interleaved in the sequence that
+/// do not belong to the chain. These other instructions must not use
+/// the "chain" register at any point.
+///
+/// We currently only support chains where the "chain" operand is killed
+/// at each link in the chain for simplicity.
+/// A chain has three important instructions - Start, Last and Kill.
+///   * The start instruction is the first instruction in the chain.
+///   * Last is the final instruction in the chain.
+///   * Kill may or may not be defined. If defined, Kill is the instruction
+///     where the outgoing value of the Last instruction is killed.
+///     This information is important as if we know the outgoing value is
+///     killed with no intervening uses, we can safely change its register.
+///
+/// Without a kill instruction, we must assume the outgoing value escapes
+/// beyond our model and either must not change its register or must
+/// create a fixup FMOV to keep the old register value consistent.
+///
+class Chain {
+public:
+  /// The important (marker) instructions.
+  MachineInstr *StartInst, *LastInst, *KillInst;
+  /// The index, from the start of the basic block, that each marker
+  /// appears. These are stored so we can do quick interval tests.
+  unsigned StartInstIdx, LastInstIdx, KillInstIdx;
+  /// All instructions in the chain.
+  std::set<MachineInstr*> Insts;
+  /// True if KillInst cannot be modified. If this is true,
+  /// we cannot change LastInst's outgoing register.
+  /// This will be true for tied values and regmasks.
+  bool KillIsImmutable;
+  /// The "color" of LastInst. This will be the preferred chain color,
+  /// as changing intermediate nodes is easy but changing the last
+  /// instruction can be more tricky.
+  Color LastColor;
+
+  Chain(MachineInstr *MI, unsigned Idx, Color C) :
+  StartInst(MI), LastInst(MI), KillInst(NULL),
+  StartInstIdx(Idx), LastInstIdx(Idx), KillInstIdx(0),
+  LastColor(C) {
+    Insts.insert(MI);
+  }
+
+  /// Add a new instruction into the chain. The instruction's dest operand
+  /// has the given color.
+  void add(MachineInstr *MI, unsigned Idx, Color C) {
+    LastInst = MI;
+    LastInstIdx = Idx;
+    LastColor = C;
+
+    Insts.insert(MI);
+  }
+
+  /// Return true if MI is a member of the chain.
+  bool contains(MachineInstr *MI) { return Insts.count(MI) > 0; }
+
+  /// Return the number of instructions in the chain.
+  unsigned size() const {
+    return Insts.size();
+  }
+
+  /// Inform the chain that its last active register (the dest register of
+  /// LastInst) is killed by MI with no intervening uses or defs.
+  void setKill(MachineInstr *MI, unsigned Idx, bool Immutable) {
+    KillInst = MI;
+    KillInstIdx = Idx;
+    KillIsImmutable = Immutable;
+  }
+
+  /// Return the first instruction in the chain.
+  MachineInstr *getStart() const { return StartInst; }
+  /// Return the last instruction in the chain.
+  MachineInstr *getLast() const { return LastInst; }
+  /// Return the "kill" instruction (as set with setKill()) or NULL.
+  MachineInstr *getKill() const { return KillInst; }
+  /// Return an instruction that can be used as an iterator for the end
+  /// of the chain. This is the maximum of KillInst (if set) and LastInst.
+  MachineInstr *getEnd() const {
+    return ++MachineBasicBlock::iterator(KillInst ? KillInst : LastInst);
+  }
+
+  /// Can the Kill instruction (assuming one exists) be modified?
+  bool isKillImmutable() const { return KillIsImmutable; }
+
+  /// Return the preferred color of this chain.
+  Color getPreferredColor() {
+    if (OverrideBalance != 0)
+      return OverrideBalance == 1 ? Color::Even : Color::Odd;
+    return LastColor;
+  }
+
+  /// Return true if this chain (StartInst..KillInst) overlaps with Other.
+  bool rangeOverlapsWith(Chain *Other) {
+    unsigned End = KillInst ? KillInstIdx : LastInstIdx;
+    unsigned OtherEnd = Other->KillInst ?
+      Other->KillInstIdx : Other->LastInstIdx;
+
+    return StartInstIdx <= OtherEnd && Other->StartInstIdx <= End;
+  }
+
+  /// Return true if this chain starts before Other.
+  bool startsBefore(Chain *Other) {
+    return StartInstIdx < Other->StartInstIdx;
+  }
+
+  /// Return true if the group will require a fixup MOV at the end.
+  bool requiresFixup() const {
+    return (getKill() && isKillImmutable()) || !getKill();
+  }
+
+  /// Return a simple string representation of the chain.
+  std::string str() const {
+    std::string S;
+    raw_string_ostream OS(S);
+    
+    OS << "{";
+    StartInst->print(OS, NULL, true);
+    OS << " -> ";
+    LastInst->print(OS, NULL, true);
+    if (KillInst) {
+      OS << " (kill @ ";
+      KillInst->print(OS, NULL, true);
+      OS << ")";
+    }
+    OS << "}";
+
+    return OS.str();
+  }
+
+};
+
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
+
+bool AArch64A57FPLoadBalancing::runOnMachineFunction(MachineFunction &F) {
+  bool Changed = false;
+  DEBUG(dbgs() << "***** AArch64A57FPLoadBalancing *****\n");
+
+  const TargetMachine &TM = F.getTarget();
+  MRI = &F.getRegInfo();
+  TRI = F.getRegInfo().getTargetRegisterInfo();
+  TII = TM.getSubtarget<AArch64Subtarget>().getInstrInfo();
+  RCI.runOnMachineFunction(F);
+
+  for (auto &MBB : F) {
+    Changed |= runOnBasicBlock(MBB);
+  }
+
+  return Changed;
+}
+
+bool AArch64A57FPLoadBalancing::runOnBasicBlock(MachineBasicBlock &MBB) {
+  bool Changed = false;
+  DEBUG(dbgs() << "Running on MBB: " << MBB << " - scanning instructions...\n");
+
+  // First, scan the basic block producing a set of chains.
+
+  // The currently "active" chains - chains that can be added to and haven't
+  // been killed yet. This is keyed by register - all chains can only have one
+  // "link" register between each inst in the chain.
+  std::map<unsigned, Chain*> ActiveChains;
+  std::set<Chain*> AllChains;
+  unsigned Idx = 0;
+  for (auto &MI : MBB)
+    scanInstruction(&MI, Idx++, ActiveChains, AllChains);
+
+  DEBUG(dbgs() << "Scan complete, "<< AllChains.size() << " chains created.\n");
+
+  // Group the chains into disjoint sets based on their liveness range. This is
+  // a poor-man's version of graph coloring. Ideally we'd create an interference
+  // graph and perform full-on graph coloring on that, but;
+  //   (a) That's rather heavyweight for only two colors.
+  //   (b) We expect multiple disjoint interference regions - in practice the live
+  //       range of chains is quite small and they are clustered between loads
+  //       and stores.
+  EquivalenceClasses<Chain*> EC;
+  for (auto *I : AllChains)
+    EC.insert(I);
+
+  for (auto *I : AllChains) {
+    for (auto *J : AllChains) {
+      if (I != J && I->rangeOverlapsWith(J))
+        EC.unionSets(I, J);
+    }
+  }
+  DEBUG(dbgs() << "Created " << EC.getNumClasses() << " disjoint sets.\n");
+
+  // Now we assume that every member of an equivalence class interferes
+  // with every other member of that class, and with no members of other classes.
+
+  // Convert the EquivalenceClasses to a simpler set of sets.
+  std::vector<std::vector<Chain*> > V;
+  for (auto I = EC.begin(), E = EC.end(); I != E; ++I) {
+    std::vector<Chain*> Cs(EC.member_begin(I), EC.member_end());
+    if (Cs.empty()) continue;
+    V.push_back(Cs);
+  }
+
+  // Now we have a set of sets, order them by start address so
+  // we can iterate over them sequentially.
+  std::sort(V.begin(), V.end(),
+            [](const std::vector<Chain*> &A,
+               const std::vector<Chain*> &B) {
+      return A.front()->startsBefore(B.front());
+    });
+
+  // As we only have two colors, we can track the global (BB-level) balance of
+  // odds versus evens. We aim to keep this near zero to keep both execution
+  // units fed.
+  // Positive means we're even-heavy, negative we're odd-heavy.
+  //
+  // FIXME: If chains have interdependencies, for example:
+  //   mul r0, r1, r2
+  //   mul r3, r0, r1
+  // We do not model this and may color each one differently, assuming we'll
+  // get ILP when we obviously can't. This hasn't been seen to be a problem
+  // in practice so far, so we simplify the algorithm by ignoring it.
+  int Parity = 0;
+
+  for (auto &I : V)
+    Changed |= colorChainSet(I, MBB, Parity);
+
+  for (auto *C : AllChains)
+    delete C;
+
+  return Changed;
+}
+
+Chain *AArch64A57FPLoadBalancing::getAndEraseNext(Color PreferredColor,
+                                                  std::vector<Chain*> &L) {
+  if (L.empty())
+    return nullptr;
+
+  // We try and get the best candidate from L to color next, given that our
+  // preferred color is "PreferredColor". L is ordered from larger to smaller
+  // chains. It is beneficial to color the large chains before the small chains,
+  // but if we can't find a chain of the maximum length with the preferred color,
+  // we fuzz the size and look for slightly smaller chains before giving up and
+  // returning a chain that must be recolored.
+
+  // FIXME: Does this need to be configurable?
+  const unsigned SizeFuzz = 1;
+  unsigned MinSize = L.front()->size() - SizeFuzz;
+  for (auto I = L.begin(), E = L.end(); I != E; ++I) {
+    if ((*I)->size() <= MinSize) {
+      // We've gone past the size limit. Return the previous item.
+      Chain *Ch = *--I;
+      L.erase(I);
+      return Ch;
+    }
+
+    if ((*I)->getPreferredColor() == PreferredColor) {
+      Chain *Ch = *I;
+      L.erase(I);
+      return Ch;
+    }
+  }
+  
+  // Bailout case - just return the first item.
+  Chain *Ch = L.front();
+  L.erase(L.begin());
+  return Ch;
+}
+
+bool AArch64A57FPLoadBalancing::colorChainSet(std::vector<Chain*> GV,
+                                              MachineBasicBlock &MBB,
+                                              int &Parity) {
+  bool Changed = false;
+  DEBUG(dbgs() << "colorChainSet(): #sets=" << GV.size() << "\n");
+
+  // Sort by descending size order so that we allocate the most important
+  // sets first.
+  // Tie-break equivalent sizes by sorting chains requiring fixups before
+  // those without fixups. The logic here is that we should look at the
+  // chains that we cannot change before we look at those we can,
+  // so the parity counter is updated and we know what color we should
+  // change them to!
+  std::sort(GV.begin(), GV.end(), [](const Chain *G1, const Chain *G2) {
+      if (G1->size() != G2->size())
+        return G1->size() > G2->size();
+      return G1->requiresFixup() > G2->requiresFixup();
+    });
+
+  Color PreferredColor = Parity < 0 ? Color::Even : Color::Odd;
+  while (Chain *G = getAndEraseNext(PreferredColor, GV)) {
+    // Start off by assuming we'll color to our own preferred color.
+    Color C = PreferredColor;
+    if (Parity == 0)
+      // But if we really don't care, use the chain's preferred color.
+      C = G->getPreferredColor();
+
+    DEBUG(dbgs() << " - Parity=" << Parity << ", Color="
+          << ColorNames[(int)C] << "\n");
+
+    // If we'll need a fixup FMOV, don't bother. Testing has shown that this
+    // happens infrequently and when it does it has at least a 50% chance of
+    // slowing code down instead of speeding it up.
+    if (G->requiresFixup() && C != G->getPreferredColor()) {
+      C = G->getPreferredColor();
+      DEBUG(dbgs() << " - " << G->str() << " - not worthwhile changing; "
+            "color remains " << ColorNames[(int)C] << "\n");
+    }
+
+    Changed |= colorChain(G, C, MBB);
+
+    Parity += (C == Color::Even) ? G->size() : -G->size();
+    PreferredColor = Parity < 0 ? Color::Even : Color::Odd;
+  }
+
+  return Changed;
+}
+
+int AArch64A57FPLoadBalancing::scavengeRegister(Chain *G, Color C,
+                                                MachineBasicBlock &MBB) {
+  RegScavenger RS;
+  RS.enterBasicBlock(&MBB);
+  RS.forward(MachineBasicBlock::iterator(G->getStart()));
+
+  // Can we find an appropriate register that is available throughout the life 
+  // of the chain?
+  unsigned RegClassID = G->getStart()->getDesc().OpInfo[0].RegClass;
+  BitVector AvailableRegs = RS.getRegsAvailable(TRI->getRegClass(RegClassID));
+  for (MachineBasicBlock::iterator I = G->getStart(), E = G->getEnd();
+       I != E; ++I) {
+    RS.forward(I);
+    AvailableRegs &= RS.getRegsAvailable(TRI->getRegClass(RegClassID));
+
+    // Remove any registers clobbered by a regmask.
+    for (auto J : I->operands()) {
+      if (J.isRegMask())
+        AvailableRegs.clearBitsNotInMask(J.getRegMask());
+    }
+  }
+
+  // Make sure we allocate in-order, to get the cheapest registers first.
+  auto Ord = RCI.getOrder(TRI->getRegClass(RegClassID));
+  for (auto Reg : Ord) {
+    if (!AvailableRegs[Reg])
+      continue;
+    if ((C == Color::Even && (Reg % 2) == 0) ||
+        (C == Color::Odd && (Reg % 2) == 1))
+      return Reg;
+  }
+
+  return -1;
+}
+
+bool AArch64A57FPLoadBalancing::colorChain(Chain *G, Color C,
+                                           MachineBasicBlock &MBB) {
+  bool Changed = false;
+  DEBUG(dbgs() << " - colorChain(" << G->str() << ", "
+        << ColorNames[(int)C] << ")\n");
+
+  // Try and obtain a free register of the right class. Without a register
+  // to play with we cannot continue.
+  int Reg = scavengeRegister(G, C, MBB);
+  if (Reg == -1) {
+    DEBUG(dbgs() << "Scavenging (thus coloring) failed!\n");
+    return false;
+  }
+  DEBUG(dbgs() << " - Scavenged register: " << TRI->getName(Reg) << "\n");
+
+  std::map<unsigned, unsigned> Substs;
+  for (MachineBasicBlock::iterator I = G->getStart(), E = G->getEnd();
+       I != E; ++I) {
+    if (!G->contains(I) &&
+        (&*I != G->getKill() || G->isKillImmutable()))
+      continue;
+
+    // I is a member of G, or I is a mutable instruction that kills G.
+
+    std::vector<unsigned> ToErase;
+    for (auto &U : I->operands()) {
+      if (U.isReg() && U.isUse() && Substs.find(U.getReg()) != Substs.end()) {
+        unsigned OrigReg = U.getReg();
+        U.setReg(Substs[OrigReg]);
+        if (U.isKill())
+          // Don't erase straight away, because there may be other operands
+          // that also reference this substitution!
+          ToErase.push_back(OrigReg);
+      } else if (U.isRegMask()) {
+        for (auto J : Substs) {
+          if (U.clobbersPhysReg(J.first))
+            ToErase.push_back(J.first);
+        }
+      }
+    }
+    // Now it's safe to remove the substs identified earlier.
+    for (auto J : ToErase)
+      Substs.erase(J);
+
+    // Only change the def if this isn't the last instruction.
+    if (&*I != G->getKill()) {
+      MachineOperand &MO = I->getOperand(0);
+
+      bool Change = TransformAll || getColor(MO.getReg()) != C;
+      if (G->requiresFixup() && &*I == G->getLast())
+        Change = false;
+
+      if (Change) {
+        Substs[MO.getReg()] = Reg;
+        MO.setReg(Reg);
+        MRI->setPhysRegUsed(Reg);
+
+        Changed = true;
+      }
+    }
+  }
+  assert(Substs.size() == 0 && "No substitutions should be left active!");
+
+  if (G->getKill()) {
+    DEBUG(dbgs() << " - Kill instruction seen.\n");
+  } else {
+    // We didn't have a kill instruction, but we didn't seem to need to change
+    // the destination register anyway.
+    DEBUG(dbgs() << " - Destination register not changed.\n");
+  }
+  return Changed;
+}
+
+void AArch64A57FPLoadBalancing::
+scanInstruction(MachineInstr *MI, unsigned Idx, 
+                std::map<unsigned, Chain*> &ActiveChains,
+                std::set<Chain*> &AllChains) {
+  // Inspect "MI", updating ActiveChains and AllChains.
+
+  if (isMul(MI)) {
+
+    for (auto &I : MI->operands())
+      maybeKillChain(I, Idx, ActiveChains);
+
+    // Create a new chain. Multiplies don't require forwarding so can go on any
+    // unit.
+    unsigned DestReg = MI->getOperand(0).getReg();
+
+    DEBUG(dbgs() << "New chain started for register "
+          << TRI->getName(DestReg) << " at " << *MI);
+
+    Chain *G = new Chain(MI, Idx, getColor(DestReg));
+    ActiveChains[DestReg] = G;
+    AllChains.insert(G);
+
+  } else if (isMla(MI)) {
+
+    // It is beneficial to keep MLAs on the same functional unit as their
+    // accumulator operand.
+    unsigned DestReg  = MI->getOperand(0).getReg();
+    unsigned AccumReg = MI->getOperand(3).getReg();
+
+    maybeKillChain(MI->getOperand(1), Idx, ActiveChains);
+    maybeKillChain(MI->getOperand(2), Idx, ActiveChains);
+    if (DestReg != AccumReg)
+      maybeKillChain(MI->getOperand(0), Idx, ActiveChains);
+
+    if (ActiveChains.find(AccumReg) != ActiveChains.end()) {
+      DEBUG(dbgs() << "Chain found for accumulator register "
+            << TRI->getName(AccumReg) << " in MI " << *MI);
+
+      // For simplicity we only chain together sequences of MULs/MLAs where the
+      // accumulator register is killed on each instruction. This means we don't
+      // need to track other uses of the registers we want to rewrite.
+      //
+      // FIXME: We could extend to handle the non-kill cases for more coverage.
+      if (MI->getOperand(3).isKill()) {
+        // Add to chain.
+        DEBUG(dbgs() << "Instruction was successfully added to chain.\n");
+        ActiveChains[AccumReg]->add(MI, Idx, getColor(DestReg));
+        // Handle cases where the destination is not the same as the accumulator.
+        ActiveChains[DestReg] = ActiveChains[AccumReg];
+        return;
+      }
+
+      DEBUG(dbgs() << "Cannot add to chain because accumulator operand wasn't "
+            << "marked <kill>!\n");
+      maybeKillChain(MI->getOperand(3), Idx, ActiveChains);
+    }
+
+    DEBUG(dbgs() << "Creating new chain for dest register "
+          << TRI->getName(DestReg) << "\n");
+    Chain *G = new Chain(MI, Idx, getColor(DestReg));
+    ActiveChains[DestReg] = G;
+    AllChains.insert(G);
+
+  } else {
+
+    // Non-MUL or MLA instruction. Invalidate any chain in the uses or defs
+    // lists.
+    for (auto &I : MI->operands())
+      maybeKillChain(I, Idx, ActiveChains);
+
+  }
+}
+
+void AArch64A57FPLoadBalancing::
+maybeKillChain(MachineOperand &MO, unsigned Idx,
+               std::map<unsigned, Chain*> &ActiveChains) {
+  // Given an operand and the set of active chains (keyed by register),
+  // determine if a chain should be ended and remove from ActiveChains.
+  MachineInstr *MI = MO.getParent();
+
+  if (MO.isReg()) {
+
+    // If this is a KILL of a current chain, record it.
+    if (MO.isKill() && ActiveChains.find(MO.getReg()) != ActiveChains.end()) {
+      DEBUG(dbgs() << "Kill seen for chain " << TRI->getName(MO.getReg())
+            << "\n");
+      ActiveChains[MO.getReg()]->setKill(MI, Idx, /*Immutable=*/MO.isTied());
+    }
+    ActiveChains.erase(MO.getReg());
+
+  } else if (MO.isRegMask()) {
+
+    for (auto I = ActiveChains.begin(), E = ActiveChains.end();
+         I != E; ++I) {
+      if (MO.clobbersPhysReg(I->first)) {
+        DEBUG(dbgs() << "Kill (regmask) seen for chain "
+              << TRI->getName(I->first) << "\n");
+        I->second->setKill(MI, Idx, /*Immutable=*/true);
+        ActiveChains.erase(I);
+      }
+    }
+
+  }
+}
+
+Color AArch64A57FPLoadBalancing::getColor(unsigned Reg) {
+  if ((TRI->getEncodingValue(Reg) % 2) == 0)
+    return Color::Even;
+  else
+    return Color::Odd;
+}
+
+// Factory function used by AArch64TargetMachine to add the pass to the passmanager.
+FunctionPass *llvm::createAArch64A57FPLoadBalancing() {
+  return new AArch64A57FPLoadBalancing();
+}
diff --git a/lib/Target/AArch64/AArch64InstrFormats.td b/lib/Target/AArch64/AArch64InstrFormats.td
index 5007172..4876c7d 100644
--- a/lib/Target/AArch64/AArch64InstrFormats.td
+++ b/lib/Target/AArch64/AArch64InstrFormats.td
@@ -1624,7 +1624,7 @@ class AddSubRegAlias<string asm, Instruction inst, RegisterClass dstRegtype,
 
 multiclass AddSub<bit isSub, string mnemonic,
                   SDPatternOperator OpNode = null_frag> {
-  let hasSideEffects = 0 in {
+  let hasSideEffects = 0, isReMaterializable = 1, isAsCheapAsAMove = 1 in {
   // Add/Subtract immediate
   def Wri  : BaseAddSubImm<isSub, 0, GPR32sp, GPR32sp, addsub_shifted_imm32,
                            mnemonic, OpNode> {
@@ -1949,14 +1949,14 @@ class LogicalRegAlias<string asm, Instruction inst, RegisterClass regtype>
 
 multiclass LogicalImm<bits<2> opc, string mnemonic, SDNode OpNode,
                       string Alias> {
-  let AddedComplexity = 6 in
+  let AddedComplexity = 6, isReMaterializable = 1, isAsCheapAsAMove = 1 in
   def Wri : BaseLogicalImm<opc, GPR32sp, GPR32, logical_imm32, mnemonic,
                            [(set GPR32sp:$Rd, (OpNode GPR32:$Rn,
                                                logical_imm32:$imm))]> {
     let Inst{31} = 0;
     let Inst{22} = 0; // 64-bit version has an additional bit of immediate.
   }
-  let AddedComplexity = 6 in
+  let AddedComplexity = 6, isReMaterializable = 1, isAsCheapAsAMove = 1 in
   def Xri : BaseLogicalImm<opc, GPR64sp, GPR64, logical_imm64, mnemonic,
                            [(set GPR64sp:$Rd, (OpNode GPR64:$Rn,
                                                logical_imm64:$imm))]> {
@@ -2001,8 +2001,10 @@ class BaseLogicalRegPseudo<RegisterClass regtype, SDPatternOperator OpNode>
 // Split from LogicalImm as not all instructions have both.
 multiclass LogicalReg<bits<2> opc, bit N, string mnemonic,
                       SDPatternOperator OpNode> {
+  let isReMaterializable = 1, isAsCheapAsAMove = 1 in {
   def Wrr : BaseLogicalRegPseudo<GPR32, OpNode>;
   def Xrr : BaseLogicalRegPseudo<GPR64, OpNode>;
+  }
 
   def Wrs : BaseLogicalSReg<opc, N, GPR32, logical_shifted_reg32, mnemonic,
                             [(set GPR32:$Rd, (OpNode GPR32:$Rn,
diff --git a/lib/Target/AArch64/AArch64InstrInfo.cpp b/lib/Target/AArch64/AArch64InstrInfo.cpp
index ce85b2c..b702275 100644
--- a/lib/Target/AArch64/AArch64InstrInfo.cpp
+++ b/lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -541,6 +541,51 @@ void AArch64InstrInfo::insertSelect(MachineBasicBlock &MBB,
       CC);
 }
 
+// FIXME: this implementation should be micro-architecture dependent, so a
+// micro-architecture target hook should be introduced here in future.
+bool AArch64InstrInfo::isAsCheapAsAMove(const MachineInstr *MI) const {
+  if (!Subtarget.isCortexA57() && !Subtarget.isCortexA53())
+    return MI->isAsCheapAsAMove();
+
+  switch (MI->getOpcode()) {
+  default:
+    return false;
+
+  // add/sub on register without shift
+  case AArch64::ADDWri:
+  case AArch64::ADDXri:
+  case AArch64::SUBWri:
+  case AArch64::SUBXri:
+    return (MI->getOperand(3).getImm() == 0);
+
+  // logical ops on immediate
+  case AArch64::ANDWri:
+  case AArch64::ANDXri:
+  case AArch64::EORWri:
+  case AArch64::EORXri:
+  case AArch64::ORRWri:
+  case AArch64::ORRXri:
+    return true;
+
+  // logical ops on register without shift
+  case AArch64::ANDWrr:
+  case AArch64::ANDXrr:
+  case AArch64::BICWrr:
+  case AArch64::BICXrr:
+  case AArch64::EONWrr:
+  case AArch64::EONXrr:
+  case AArch64::EORWrr:
+  case AArch64::EORXrr:
+  case AArch64::ORNWrr:
+  case AArch64::ORNXrr:
+  case AArch64::ORRWrr:
+  case AArch64::ORRXrr:
+    return true;
+  }
+
+  llvm_unreachable("Unknown opcode to check as cheap as a move!");
+}
+
 bool AArch64InstrInfo::isCoalescableExtInstr(const MachineInstr &MI,
                                              unsigned &SrcReg, unsigned &DstReg,
                                              unsigned &SubIdx) const {
diff --git a/lib/Target/AArch64/AArch64InstrInfo.h b/lib/Target/AArch64/AArch64InstrInfo.h
index f70b82b..b27565e 100644
--- a/lib/Target/AArch64/AArch64InstrInfo.h
+++ b/lib/Target/AArch64/AArch64InstrInfo.h
@@ -46,6 +46,8 @@ public:
 
   unsigned GetInstSizeInBytes(const MachineInstr *MI) const;
 
+  bool isAsCheapAsAMove(const MachineInstr *MI) const override;
+
   bool isCoalescableExtInstr(const MachineInstr &MI, unsigned &SrcReg,
                              unsigned &DstReg, unsigned &SubIdx) const override;
 
diff --git a/lib/Target/AArch64/AArch64Subtarget.h b/lib/Target/AArch64/AArch64Subtarget.h
index 52124f6..10c646d 100644
--- a/lib/Target/AArch64/AArch64Subtarget.h
+++ b/lib/Target/AArch64/AArch64Subtarget.h
@@ -100,6 +100,8 @@ public:
   bool isTargetMachO() const { return TargetTriple.isOSBinFormatMachO(); }
 
   bool isCyclone() const { return CPUString == "cyclone"; }
+  bool isCortexA57() const { return CPUString == "cortex-a57"; }
+  bool isCortexA53() const { return CPUString == "cortex-a53"; }
 
   /// getMaxInlineSizeThreshold - Returns the maximum memset / memcpy size
   /// that still makes it profitable to inline the call.
diff --git a/lib/Target/AArch64/AArch64TargetMachine.cpp b/lib/Target/AArch64/AArch64TargetMachine.cpp
index f99b90b..722e5e7 100644
--- a/lib/Target/AArch64/AArch64TargetMachine.cpp
+++ b/lib/Target/AArch64/AArch64TargetMachine.cpp
@@ -59,6 +59,17 @@ EnableAtomicTidy("aarch64-atomic-cfg-tidy", cl::Hidden,
                           " to make use of cmpxchg flow-based information"),
                  cl::init(true));
 
+static cl::opt<bool>
+EnableEarlyIfConversion("aarch64-enable-early-ifcvt", cl::Hidden,
+                        cl::desc("Run early if-conversion"),
+                        cl::init(true));
+
+
+static cl::opt<bool>
+EnableA53Fix835769("aarch64-fix-cortex-a53-835769", cl::Hidden,
+                cl::desc("Work around Cortex-A53 erratum 835769"),
+                cl::init(false));
+
 extern "C" void LLVMInitializeAArch64Target() {
   // Register the target.
   RegisterTargetMachine<AArch64leTargetMachine> X(TheAArch64leTarget);
@@ -176,7 +187,8 @@ bool AArch64PassConfig::addInstSelector() {
 bool AArch64PassConfig::addILPOpts() {
   if (EnableCCMP)
     addPass(createAArch64ConditionalCompares());
-  addPass(&EarlyIfConverterID);
+  if (EnableEarlyIfConversion)
+    addPass(&EarlyIfConverterID);
   if (EnableStPairSuppress)
     addPass(createAArch64StorePairSuppressPass());
   return true;
@@ -193,6 +205,10 @@ bool AArch64PassConfig::addPostRegAlloc() {
   // Change dead register definitions to refer to the zero register.
   if (TM->getOptLevel() != CodeGenOpt::None && EnableDeadRegisterElimination)
     addPass(createAArch64DeadRegisterDefinitions());
+  if (TM->getOptLevel() != CodeGenOpt::None &&
+      TM->getSubtarget<AArch64Subtarget>().isCortexA57())
+    // Improve performance for some FP/SIMD code for A57.
+    addPass(createAArch64A57FPLoadBalancing());
   return true;
 }
 
@@ -206,6 +222,8 @@ bool AArch64PassConfig::addPreSched2() {
 }
 
 bool AArch64PassConfig::addPreEmitPass() {
+  if (EnableA53Fix835769)
+    addPass(createAArch64A53Fix835769());
   // Relax conditional branch instructions if they're otherwise out of
   // range of their destination.
   addPass(createAArch64BranchRelaxation());
diff --git a/lib/Target/AArch64/Android.mk b/lib/Target/AArch64/Android.mk
index 6b29c77..d7b3317 100644
--- a/lib/Target/AArch64/Android.mk
+++ b/lib/Target/AArch64/Android.mk
@@ -15,6 +15,8 @@ aarch64_codegen_TBLGEN_TABLES := \
   AArch64GenMCPseudoLowering.inc \
 
 aarch64_codegen_SRC_FILES := \
+  AArch64A53Fix835769.cpp \
+  AArch64A57FPLoadBalancing.cpp \
   AArch64AddressTypePromotion.cpp \
   AArch64AdvSIMDScalarPass.cpp \
   AArch64AsmPrinter.cpp \
diff --git a/lib/Target/AArch64/CMakeLists.txt b/lib/Target/AArch64/CMakeLists.txt
index 789d549..c2f0488 100644
--- a/lib/Target/AArch64/CMakeLists.txt
+++ b/lib/Target/AArch64/CMakeLists.txt
@@ -15,6 +15,7 @@ tablegen(LLVM AArch64GenDisassemblerTables.inc -gen-disassembler)
 add_public_tablegen_target(AArch64CommonTableGen)
 
 add_llvm_target(AArch64CodeGen
+  AArch64A57FPLoadBalancing.cpp
   AArch64AddressTypePromotion.cpp
   AArch64AdvSIMDScalarPass.cpp
   AArch64AsmPrinter.cpp
@@ -25,6 +26,7 @@ add_llvm_target(AArch64CodeGen
   AArch64DeadRegisterDefinitionsPass.cpp
   AArch64ExpandPseudoInsts.cpp
   AArch64FastISel.cpp
+  AArch64A53Fix835769.cpp
   AArch64FrameLowering.cpp
   AArch64ISelDAGToDAG.cpp
   AArch64ISelLowering.cpp