[llvm] r265317 - Revert r265309 and r265312 because they caused some errors I need to investigate.

Wei Mi via llvm-commits llvm-commits at lists.llvm.org
Mon Apr 4 11:43:38 PDT 2016


My patch caused llvm bootstrap error on several targets. I am looking
at it. Will fix the error as soon as possible.

Wei.

On Mon, Apr 4, 2016 at 11:39 AM, Quentin Colombet <qcolombet at apple.com> wrote:
>
> On Apr 4, 2016, at 11:35 AM, Chandler Carruth <chandlerc at google.com> wrote:
>
> On Mon, Apr 4, 2016 at 10:50 AM Wei Mi via llvm-commits
> <llvm-commits at lists.llvm.org> wrote:
>>
>> Author: wmi
>> Date: Mon Apr  4 12:45:03 2016
>> New Revision: 265317
>>
>> URL: http://llvm.org/viewvc/llvm-project?rev=265317&view=rev
>> Log:
>> Revert r265309 and r265312 because they caused some errors I need to
>> investigate.
>
>
> Ouch.
>
> So, we were really counting on these to address a severe compile time
> regression for the sanatizers with Quentin's patch in r263460.
>
> Quentin, I wonder if it would make sense to revert r263460 until Wei's fixes
> can land? Our ASan users are really having trouble because of the widespread
> compile time regressions this causes. While I know you're patch fixes
> compile time issues as well, Richard had indicated that we really should
> prioritize not *regressing* compile time... Thoughts?
>
>
> Works for me as long as we keep pushing this one further to reland the whole
> thing.
>
> Q.
>
>
> -Chandler
>
>>
>>
>> Added:
>>     llvm/trunk/test/CodeGen/AArch64/aarch64-deferred-spilling.ll
>>       - copied unchanged from r265308,
>> llvm/trunk/test/CodeGen/AArch64/aarch64-deferred-spilling.ll
>> Removed:
>>     llvm/trunk/test/CodeGen/X86/hoist-spill.ll
>>     llvm/trunk/test/CodeGen/X86/new-remat.ll
>> Modified:
>>     llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h
>>     llvm/trunk/lib/CodeGen/InlineSpiller.cpp
>>     llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp
>>     llvm/trunk/lib/CodeGen/RegAllocBase.cpp
>>     llvm/trunk/lib/CodeGen/RegAllocBase.h
>>     llvm/trunk/lib/CodeGen/RegAllocBasic.cpp
>>     llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
>>     llvm/trunk/lib/CodeGen/RegAllocPBQP.cpp
>>     llvm/trunk/lib/CodeGen/Spiller.h
>>     llvm/trunk/lib/CodeGen/SplitKit.cpp
>>     llvm/trunk/lib/CodeGen/SplitKit.h
>>     llvm/trunk/test/CodeGen/X86/fp128-compare.ll
>>     llvm/trunk/test/CodeGen/X86/ragreedy-hoist-spill.ll
>>
>> Modified: llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h (original)
>> +++ llvm/trunk/include/llvm/CodeGen/LiveRangeEdit.h Mon Apr  4 12:45:03
>> 2016
>> @@ -72,10 +72,6 @@ private:
>>    /// ScannedRemattable - true when remattable values have been
>> identified.
>>    bool ScannedRemattable;
>>
>> -  /// DeadRemats - The saved instructions which have already been dead
>> after
>> -  /// rematerialization but not deleted yet -- to be done in
>> postOptimization.
>> -  SmallPtrSet<MachineInstr *, 32> *DeadRemats;
>> -
>>    /// Remattable - Values defined by remattable instructions as
>> identified by
>>    /// tii.isTriviallyReMaterializable().
>>    SmallPtrSet<const VNInfo*,4> Remattable;
>> @@ -120,16 +116,13 @@ public:
>>    /// @param vrm Map of virtual registers to physical registers for this
>>    ///            function.  If NULL, no virtual register map updates will
>>    ///            be done.  This could be the case if called before
>> Regalloc.
>> -  /// @param deadRemats The collection of all the instructions defining
>> an
>> -  ///                   original reg and are dead after remat.
>>    LiveRangeEdit(LiveInterval *parent, SmallVectorImpl<unsigned> &newRegs,
>>                  MachineFunction &MF, LiveIntervals &lis, VirtRegMap *vrm,
>> -                Delegate *delegate = nullptr,
>> -                SmallPtrSet<MachineInstr *, 32> *deadRemats = nullptr)
>> +                Delegate *delegate = nullptr)
>>        : Parent(parent), NewRegs(newRegs), MRI(MF.getRegInfo()), LIS(lis),
>> -        VRM(vrm), TII(*MF.getSubtarget().getInstrInfo()),
>> TheDelegate(delegate),
>> -        FirstNew(newRegs.size()), ScannedRemattable(false),
>> -        DeadRemats(deadRemats) {
>> +        VRM(vrm), TII(*MF.getSubtarget().getInstrInfo()),
>> +        TheDelegate(delegate), FirstNew(newRegs.size()),
>> +        ScannedRemattable(false) {
>>      MRI.setDelegate(this);
>>    }
>>
>> @@ -149,16 +142,6 @@ public:
>>    bool empty() const { return size() == 0; }
>>    unsigned get(unsigned idx) const { return NewRegs[idx+FirstNew]; }
>>
>> -  /// pop_back - It allows LiveRangeEdit users to drop new registers.
>> -  /// The context is when an original def instruction of a register is
>> -  /// dead after rematerialization, we still want to keep it for
>> following
>> -  /// rematerializations. We save the def instruction in DeadRemats,
>> -  /// and replace the original dst register with a new dummy register so
>> -  /// the live range of original dst register can be shrinked normally.
>> -  /// We don't want to allocate phys register for the dummy register, so
>> -  /// we want to drop it from the NewRegs set.
>> -  void pop_back() { NewRegs.pop_back(); }
>> -
>>    ArrayRef<unsigned> regs() const {
>>      return makeArrayRef(NewRegs).slice(FirstNew);
>>    }
>> @@ -192,15 +175,15 @@ public:
>>    /// Remat - Information needed to rematerialize at a specific location.
>>    struct Remat {
>>      VNInfo *ParentVNI;      // parent_'s value at the remat location.
>> -    MachineInstr *OrigMI;   // Instruction defining OrigVNI. It contains
>> the
>> -                            // real expr for remat.
>> +    MachineInstr *OrigMI;   // Instruction defining ParentVNI.
>>      explicit Remat(VNInfo *ParentVNI) : ParentVNI(ParentVNI),
>> OrigMI(nullptr) {}
>>    };
>>
>>    /// canRematerializeAt - Determine if ParentVNI can be rematerialized
>> at
>>    /// UseIdx. It is assumed that parent_.getVNINfoAt(UseIdx) ==
>> ParentVNI.
>>    /// When cheapAsAMove is set, only cheap remats are allowed.
>> -  bool canRematerializeAt(Remat &RM, VNInfo *OrigVNI, SlotIndex UseIdx,
>> +  bool canRematerializeAt(Remat &RM,
>> +                          SlotIndex UseIdx,
>>                            bool cheapAsAMove);
>>
>>    /// rematerializeAt - Rematerialize RM.ParentVNI into DestReg by
>> inserting an
>> @@ -225,12 +208,6 @@ public:
>>      return Rematted.count(ParentVNI);
>>    }
>>
>> -  void markDeadRemat(MachineInstr *inst) {
>> -    // DeadRemats is an optional field.
>> -    if (DeadRemats)
>> -      DeadRemats->insert(inst);
>> -  }
>> -
>>    /// eraseVirtReg - Notify the delegate that Reg is no longer in use,
>> and try
>>    /// to erase it from LIS.
>>    void eraseVirtReg(unsigned Reg);
>> @@ -241,11 +218,8 @@ public:
>>    /// RegsBeingSpilled lists registers currently being spilled by the
>> register
>>    /// allocator.  These registers should not be split into new intervals
>>    /// as currently those new intervals are not guaranteed to spill.
>> -  /// NoSplit indicates this func is used after the iterations of
>> selectOrSplit
>> -  /// where registers should not be split into new intervals.
>> -  void eliminateDeadDefs(SmallVectorImpl<MachineInstr *> &Dead,
>> -                         ArrayRef<unsigned> RegsBeingSpilled = None,
>> -                         bool NoSplit = false);
>> +  void eliminateDeadDefs(SmallVectorImpl<MachineInstr*> &Dead,
>> +                         ArrayRef<unsigned> RegsBeingSpilled = None);
>>
>>    /// calculateRegClassAndHint - Recompute register class and hint for
>> each new
>>    /// register.
>>
>> Modified: llvm/trunk/lib/CodeGen/InlineSpiller.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/InlineSpiller.cpp?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/InlineSpiller.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/InlineSpiller.cpp Mon Apr  4 12:45:03 2016
>> @@ -48,77 +48,13 @@ STATISTIC(NumReloadsRemoved,  "Number of
>>  STATISTIC(NumFolded,          "Number of folded stack accesses");
>>  STATISTIC(NumFoldedLoads,     "Number of folded loads");
>>  STATISTIC(NumRemats,          "Number of rematerialized defs for
>> spilling");
>> +STATISTIC(NumOmitReloadSpill, "Number of omitted spills of reloads");
>> +STATISTIC(NumHoists,          "Number of hoisted spills");
>>
>>  static cl::opt<bool> DisableHoisting("disable-spill-hoist", cl::Hidden,
>>                                       cl::desc("Disable inline spill
>> hoisting"));
>>
>>  namespace {
>> -class HoistSpillHelper {
>> -  LiveIntervals &LIS;
>> -  LiveStacks &LSS;
>> -  AliasAnalysis *AA;
>> -  MachineDominatorTree &MDT;
>> -  MachineLoopInfo &Loops;
>> -  VirtRegMap &VRM;
>> -  MachineFrameInfo &MFI;
>> -  MachineRegisterInfo &MRI;
>> -  const TargetInstrInfo &TII;
>> -  const TargetRegisterInfo &TRI;
>> -  const MachineBlockFrequencyInfo &MBFI;
>> -
>> -  // Map from StackSlot to its original register.
>> -  DenseMap<int, unsigned> StackSlotToReg;
>> -  // Map from pair of (StackSlot and Original VNI) to a set of spills
>> which
>> -  // have the same stackslot and have equal values defined by Original
>> VNI.
>> -  // These spills are mergeable and are hoist candiates.
>> -  typedef DenseMap<std::pair<int, VNInfo *>, SmallPtrSet<MachineInstr *,
>> 16>>
>> -      MergeableSpillsMap;
>> -  MergeableSpillsMap MergeableSpills;
>> -
>> -  /// This is the map from original register to a set containing all its
>> -  /// siblings. To hoist a spill to another BB, we need to find out a
>> live
>> -  /// sibling there and use it as the source of the new spill.
>> -  DenseMap<unsigned, SmallSetVector<unsigned, 16>> Virt2SiblingsMap;
>> -
>> -  bool isSpillCandBB(unsigned OrigReg, VNInfo &OrigVNI, MachineBasicBlock
>> &BB,
>> -                     unsigned &LiveReg);
>> -
>> -  void rmRedundantSpills(
>> -      SmallPtrSet<MachineInstr *, 16> &Spills,
>> -      SmallVectorImpl<MachineInstr *> &SpillsToRm,
>> -      DenseMap<MachineDomTreeNode *, MachineInstr *> &SpillBBToSpill);
>> -
>> -  void getVisitOrders(
>> -      MachineBasicBlock *Root, SmallPtrSet<MachineInstr *, 16> &Spills,
>> -      SmallVectorImpl<MachineDomTreeNode *> &Orders,
>> -      SmallVectorImpl<MachineInstr *> &SpillsToRm,
>> -      DenseMap<MachineDomTreeNode *, unsigned> &SpillsToKeep,
>> -      DenseMap<MachineDomTreeNode *, MachineInstr *> &SpillBBToSpill);
>> -
>> -  void runHoistSpills(unsigned OrigReg, VNInfo &OrigVNI,
>> -                      SmallPtrSet<MachineInstr *, 16> &Spills,
>> -                      SmallVectorImpl<MachineInstr *> &SpillsToRm,
>> -                      DenseMap<MachineBasicBlock *, unsigned>
>> &SpillsToIns);
>> -
>> -public:
>> -  HoistSpillHelper(MachineFunctionPass &pass, MachineFunction &mf,
>> -                   VirtRegMap &vrm)
>> -      : LIS(pass.getAnalysis<LiveIntervals>()),
>> -        LSS(pass.getAnalysis<LiveStacks>()),
>> -        AA(&pass.getAnalysis<AAResultsWrapperPass>().getAAResults()),
>> -        MDT(pass.getAnalysis<MachineDominatorTree>()),
>> -        Loops(pass.getAnalysis<MachineLoopInfo>()), VRM(vrm),
>> -        MFI(*mf.getFrameInfo()), MRI(mf.getRegInfo()),
>> -        TII(*mf.getSubtarget().getInstrInfo()),
>> -        TRI(*mf.getSubtarget().getRegisterInfo()),
>> -        MBFI(pass.getAnalysis<MachineBlockFrequencyInfo>()) {}
>> -
>> -  void addToMergeableSpills(MachineInstr *Spill, int StackSlot,
>> -                           unsigned Original);
>> -  bool rmFromMergeableSpills(MachineInstr *Spill, int StackSlot);
>> -  void hoistAllSpills(LiveRangeEdit &Edit);
>> -};
>> -
>>  class InlineSpiller : public Spiller {
>>    MachineFunction &MF;
>>    LiveIntervals &LIS;
>> @@ -149,12 +85,56 @@ class InlineSpiller : public Spiller {
>>    // Values that failed to remat at some point.
>>    SmallPtrSet<VNInfo*, 8> UsedValues;
>>
>> +public:
>> +  // Information about a value that was defined by a copy from a sibling
>> +  // register.
>> +  struct SibValueInfo {
>> +    // True when all reaching defs were reloads: No spill is necessary.
>> +    bool AllDefsAreReloads;
>> +
>> +    // True when value is defined by an original PHI not from splitting.
>> +    bool DefByOrigPHI;
>> +
>> +    // True when the COPY defining this value killed its source.
>> +    bool KillsSource;
>> +
>> +    // The preferred register to spill.
>> +    unsigned SpillReg;
>> +
>> +    // The value of SpillReg that should be spilled.
>> +    VNInfo *SpillVNI;
>> +
>> +    // The block where SpillVNI should be spilled. Currently, this must
>> be the
>> +    // block containing SpillVNI->def.
>> +    MachineBasicBlock *SpillMBB;
>> +
>> +    // A defining instruction that is not a sibling copy or a reload, or
>> NULL.
>> +    // This can be used as a template for rematerialization.
>> +    MachineInstr *DefMI;
>> +
>> +    // List of values that depend on this one.  These values are actually
>> the
>> +    // same, but live range splitting has placed them in different
>> registers,
>> +    // or SSA update needed to insert PHI-defs to preserve SSA form.
>> This is
>> +    // copies of the current value and phi-kills.  Usually only phi-kills
>> cause
>> +    // more than one dependent value.
>> +    TinyPtrVector<VNInfo*> Deps;
>> +
>> +    SibValueInfo(unsigned Reg, VNInfo *VNI)
>> +      : AllDefsAreReloads(true), DefByOrigPHI(false), KillsSource(false),
>> +        SpillReg(Reg), SpillVNI(VNI), SpillMBB(nullptr), DefMI(nullptr)
>> {}
>> +
>> +    // Returns true when a def has been found.
>> +    bool hasDef() const { return DefByOrigPHI || DefMI; }
>> +  };
>> +
>> +private:
>> +  // Values in RegsToSpill defined by sibling copies.
>> +  typedef DenseMap<VNInfo*, SibValueInfo> SibValueMap;
>> +  SibValueMap SibValues;
>> +
>>    // Dead defs generated during spilling.
>>    SmallVector<MachineInstr*, 8> DeadDefs;
>>
>> -  // Object records spills information and does the hoisting.
>> -  HoistSpillHelper HSpiller;
>> -
>>    ~InlineSpiller() override {}
>>
>>  public:
>> @@ -167,11 +147,9 @@ public:
>>          MFI(*mf.getFrameInfo()), MRI(mf.getRegInfo()),
>>          TII(*mf.getSubtarget().getInstrInfo()),
>>          TRI(*mf.getSubtarget().getRegisterInfo()),
>> -        MBFI(pass.getAnalysis<MachineBlockFrequencyInfo>()),
>> -        HSpiller(pass, mf, vrm) {}
>> +        MBFI(pass.getAnalysis<MachineBlockFrequencyInfo>()) {}
>>
>>    void spill(LiveRangeEdit &) override;
>> -  void postOptimization();
>>
>>  private:
>>    bool isSnippet(const LiveInterval &SnipLI);
>> @@ -183,7 +161,11 @@ private:
>>    }
>>
>>    bool isSibling(unsigned Reg);
>> -  bool hoistSpillInsideBB(LiveInterval &SpillLI, MachineInstr &CopyMI);
>> +  MachineInstr *traceSiblingValue(unsigned, VNInfo*, VNInfo*);
>> +  void propagateSiblingValue(SibValueMap::iterator, VNInfo *VNI =
>> nullptr);
>> +  void analyzeSiblingValues();
>> +
>> +  bool hoistSpill(LiveInterval &SpillLI, MachineInstr &CopyMI);
>>    void eliminateRedundantSpills(LiveInterval &LI, VNInfo *VNI);
>>
>>    void markValueUsed(LiveInterval*, VNInfo*);
>> @@ -315,44 +297,417 @@ void InlineSpiller::collectRegsToSpill()
>>    }
>>  }
>>
>> +
>>
>> +//===----------------------------------------------------------------------===//
>> +//                            Sibling Values
>>
>> +//===----------------------------------------------------------------------===//
>> +
>> +// After live range splitting, some values to be spilled may be defined
>> by
>> +// copies from sibling registers. We trace the sibling copies back to the
>> +// original value if it still exists. We need it for rematerialization.
>> +//
>> +// Even when the value can't be rematerialized, we still want to
>> determine if
>> +// the value has already been spilled, or we may want to hoist the spill
>> from a
>> +// loop.
>> +
>>  bool InlineSpiller::isSibling(unsigned Reg) {
>>    return TargetRegisterInfo::isVirtualRegister(Reg) &&
>>             VRM.getOriginal(Reg) == Original;
>>  }
>>
>> -/// It is beneficial to spill to earlier place in the same BB in case
>> -/// as follows:
>> -/// There is an alternative def earlier in the same MBB.
>> -/// Hoist the spill as far as possible in SpillMBB. This can ease
>> -/// register pressure:
>> +#ifndef NDEBUG
>> +static raw_ostream &operator<<(raw_ostream &OS,
>> +                               const InlineSpiller::SibValueInfo &SVI) {
>> +  OS << "spill " << PrintReg(SVI.SpillReg) << ':'
>> +     << SVI.SpillVNI->id << '@' << SVI.SpillVNI->def;
>> +  if (SVI.SpillMBB)
>> +    OS << " in BB#" << SVI.SpillMBB->getNumber();
>> +  if (SVI.AllDefsAreReloads)
>> +    OS << " all-reloads";
>> +  if (SVI.DefByOrigPHI)
>> +    OS << " orig-phi";
>> +  if (SVI.KillsSource)
>> +    OS << " kill";
>> +  OS << " deps[";
>> +  for (VNInfo *Dep : SVI.Deps)
>> +    OS << ' ' << Dep->id << '@' << Dep->def;
>> +  OS << " ]";
>> +  if (SVI.DefMI)
>> +    OS << " def: " << *SVI.DefMI;
>> +  else
>> +    OS << '\n';
>> +  return OS;
>> +}
>> +#endif
>> +
>> +/// propagateSiblingValue - Propagate the value in SVI to dependents if
>> it is
>> +/// known.  Otherwise remember the dependency for later.
>>  ///
>> -///   x = def
>> -///   y = use x
>> -///   s = copy x
>> +/// @param SVIIter SibValues entry to propagate.
>> +/// @param VNI Dependent value, or NULL to propagate to all saved
>> dependents.
>> +void InlineSpiller::propagateSiblingValue(SibValueMap::iterator SVIIter,
>> +                                          VNInfo *VNI) {
>> +  SibValueMap::value_type *SVI = &*SVIIter;
>> +
>> +  // When VNI is non-NULL, add it to SVI's deps, and only propagate to
>> that.
>> +  TinyPtrVector<VNInfo*> FirstDeps;
>> +  if (VNI) {
>> +    FirstDeps.push_back(VNI);
>> +    SVI->second.Deps.push_back(VNI);
>> +  }
>> +
>> +  // Has the value been completely determined yet?  If not, defer
>> propagation.
>> +  if (!SVI->second.hasDef())
>> +    return;
>> +
>> +  // Work list of values to propagate.
>> +  SmallSetVector<SibValueMap::value_type *, 8> WorkList;
>> +  WorkList.insert(SVI);
>> +
>> +  do {
>> +    SVI = WorkList.pop_back_val();
>> +    TinyPtrVector<VNInfo*> *Deps = VNI ? &FirstDeps : &SVI->second.Deps;
>> +    VNI = nullptr;
>> +
>> +    SibValueInfo &SV = SVI->second;
>> +    if (!SV.SpillMBB)
>> +      SV.SpillMBB = LIS.getMBBFromIndex(SV.SpillVNI->def);
>> +
>> +    DEBUG(dbgs() << "  prop to " << Deps->size() << ": "
>> +                 << SVI->first->id << '@' << SVI->first->def << ":\t" <<
>> SV);
>> +
>> +    assert(SV.hasDef() && "Propagating undefined value");
>> +
>> +    // Should this value be propagated as a preferred spill candidate?
>> We don't
>> +    // propagate values of registers that are about to spill.
>> +    bool PropSpill = !DisableHoisting && !isRegToSpill(SV.SpillReg);
>> +    unsigned SpillDepth = ~0u;
>> +
>> +    for (VNInfo *Dep : *Deps) {
>> +      SibValueMap::iterator DepSVI = SibValues.find(Dep);
>> +      assert(DepSVI != SibValues.end() && "Dependent value not in
>> SibValues");
>> +      SibValueInfo &DepSV = DepSVI->second;
>> +      if (!DepSV.SpillMBB)
>> +        DepSV.SpillMBB = LIS.getMBBFromIndex(DepSV.SpillVNI->def);
>> +
>> +      bool Changed = false;
>> +
>> +      // Propagate defining instruction.
>> +      if (!DepSV.hasDef()) {
>> +        Changed = true;
>> +        DepSV.DefMI = SV.DefMI;
>> +        DepSV.DefByOrigPHI = SV.DefByOrigPHI;
>> +      }
>> +
>> +      // Propagate AllDefsAreReloads.  For PHI values, this computes an
>> AND of
>> +      // all predecessors.
>> +      if (!SV.AllDefsAreReloads && DepSV.AllDefsAreReloads) {
>> +        Changed = true;
>> +        DepSV.AllDefsAreReloads = false;
>> +      }
>> +
>> +      // Propagate best spill value.
>> +      if (PropSpill && SV.SpillVNI != DepSV.SpillVNI) {
>> +        if (SV.SpillMBB == DepSV.SpillMBB) {
>> +          // DepSV is in the same block.  Hoist when dominated.
>> +          if (DepSV.KillsSource && SV.SpillVNI->def <
>> DepSV.SpillVNI->def) {
>> +            // This is an alternative def earlier in the same MBB.
>> +            // Hoist the spill as far as possible in SpillMBB. This can
>> ease
>> +            // register pressure:
>> +            //
>> +            //   x = def
>> +            //   y = use x
>> +            //   s = copy x
>> +            //
>> +            // Hoisting the spill of s to immediately after the def
>> removes the
>> +            // interference between x and y:
>> +            //
>> +            //   x = def
>> +            //   spill x
>> +            //   y = use x<kill>
>> +            //
>> +            // This hoist only helps when the DepSV copy kills its
>> source.
>> +            Changed = true;
>> +            DepSV.SpillReg = SV.SpillReg;
>> +            DepSV.SpillVNI = SV.SpillVNI;
>> +            DepSV.SpillMBB = SV.SpillMBB;
>> +          }
>> +        } else {
>> +          // DepSV is in a different block.
>> +          if (SpillDepth == ~0u)
>> +            SpillDepth = Loops.getLoopDepth(SV.SpillMBB);
>> +
>> +          // Also hoist spills to blocks with smaller loop depth, but
>> make sure
>> +          // that the new value dominates.  Non-phi dependents are always
>> +          // dominated, phis need checking.
>> +
>> +          const BranchProbability MarginProb(4, 5); // 80%
>> +          // Hoist a spill to outer loop if there are multiple dependents
>> (it
>> +          // can be beneficial if more than one dependents are hoisted)
>> or
>> +          // if DepSV (the hoisting source) is hotter than SV (the
>> hoisting
>> +          // destination) (we add a 80% margin to bias a little towards
>> +          // loop depth).
>> +          bool HoistCondition =
>> +            (MBFI.getBlockFreq(DepSV.SpillMBB) >=
>> +             (MBFI.getBlockFreq(SV.SpillMBB) * MarginProb)) ||
>> +            Deps->size() > 1;
>> +
>> +          if ((Loops.getLoopDepth(DepSV.SpillMBB) > SpillDepth) &&
>> +              HoistCondition &&
>> +              (!DepSVI->first->isPHIDef() ||
>> +               MDT.dominates(SV.SpillMBB, DepSV.SpillMBB))) {
>> +            Changed = true;
>> +            DepSV.SpillReg = SV.SpillReg;
>> +            DepSV.SpillVNI = SV.SpillVNI;
>> +            DepSV.SpillMBB = SV.SpillMBB;
>> +          }
>> +        }
>> +      }
>> +
>> +      if (!Changed)
>> +        continue;
>> +
>> +      // Something changed in DepSVI. Propagate to dependents.
>> +      WorkList.insert(&*DepSVI);
>> +
>> +      DEBUG(dbgs() << "  update " << DepSVI->first->id << '@'
>> +            << DepSVI->first->def << " to:\t" << DepSV);
>> +    }
>> +  } while (!WorkList.empty());
>> +}
>> +
>> +/// traceSiblingValue - Trace a value that is about to be spilled back to
>> the
>> +/// real defining instructions by looking through sibling copies. Always
>> stay
>> +/// within the range of OrigVNI so the registers are known to carry the
>> same
>> +/// value.
>>  ///
>> -/// Hoisting the spill of s to immediately after the def removes the
>> -/// interference between x and y:
>> +/// Determine if the value is defined by all reloads, so spilling isn't
>> +/// necessary - the value is already in the stack slot.
>>  ///
>> -///   x = def
>> -///   spill x
>> -///   y = use x<kill>
>> +/// Return a defining instruction that may be a candidate for
>> rematerialization.
>>  ///
>> -/// This hoist only helps when the copy kills its source.
>> +MachineInstr *InlineSpiller::traceSiblingValue(unsigned UseReg, VNInfo
>> *UseVNI,
>> +                                               VNInfo *OrigVNI) {
>> +  // Check if a cached value already exists.
>> +  SibValueMap::iterator SVI;
>> +  bool Inserted;
>> +  std::tie(SVI, Inserted) =
>> +    SibValues.insert(std::make_pair(UseVNI, SibValueInfo(UseReg,
>> UseVNI)));
>> +  if (!Inserted) {
>> +    DEBUG(dbgs() << "Cached value " << PrintReg(UseReg) << ':'
>> +                 << UseVNI->id << '@' << UseVNI->def << ' ' <<
>> SVI->second);
>> +    return SVI->second.DefMI;
>> +  }
>> +
>> +  DEBUG(dbgs() << "Tracing value " << PrintReg(UseReg) << ':'
>> +               << UseVNI->id << '@' << UseVNI->def << '\n');
>> +
>> +  // List of (Reg, VNI) that have been inserted into SibValues, but need
>> to be
>> +  // processed.
>> +  SmallVector<std::pair<unsigned, VNInfo*>, 8> WorkList;
>> +  WorkList.push_back(std::make_pair(UseReg, UseVNI));
>> +
>> +  LiveInterval &OrigLI = LIS.getInterval(Original);
>> +  do {
>> +    unsigned Reg;
>> +    VNInfo *VNI;
>> +    std::tie(Reg, VNI) = WorkList.pop_back_val();
>> +    DEBUG(dbgs() << "  " << PrintReg(Reg) << ':' << VNI->id << '@' <<
>> VNI->def
>> +                 << ":\t");
>> +
>> +    // First check if this value has already been computed.
>> +    SVI = SibValues.find(VNI);
>> +    assert(SVI != SibValues.end() && "Missing SibValues entry");
>> +
>> +    // Trace through PHI-defs created by live range splitting.
>> +    if (VNI->isPHIDef()) {
>> +      // Stop at original PHIs.  We don't know the value at the
>> +      // predecessors. Look up the VNInfo for the current definition
>> +      // in OrigLI, to properly determine whether or not this phi was
>> +      // added by splitting.
>> +      if (VNI->def == OrigLI.getVNInfoAt(VNI->def)->def) {
>> +        DEBUG(dbgs() << "orig phi value\n");
>> +        SVI->second.DefByOrigPHI = true;
>> +        SVI->second.AllDefsAreReloads = false;
>> +        propagateSiblingValue(SVI);
>> +        continue;
>> +      }
>> +
>> +      // This is a PHI inserted by live range splitting.  We could trace
>> the
>> +      // live-out value from predecessor blocks, but that search can be
>> very
>> +      // expensive if there are many predecessors and many more PHIs as
>> +      // generated by tail-dup when it sees an indirectbr.  Instead, look
>> at
>> +      // all the non-PHI defs that have the same value as OrigVNI.  They
>> must
>> +      // jointly dominate VNI->def.  This is not optimal since VNI may
>> actually
>> +      // be jointly dominated by a smaller subset of defs, so there is a
>> change
>> +      // we will miss a AllDefsAreReloads optimization.
>> +
>> +      // Separate all values dominated by OrigVNI into PHIs and non-PHIs.
>> +      SmallVector<VNInfo*, 8> PHIs, NonPHIs;
>> +      LiveInterval &LI = LIS.getInterval(Reg);
>> +
>> +      for (LiveInterval::vni_iterator VI = LI.vni_begin(), VE =
>> LI.vni_end();
>> +           VI != VE; ++VI) {
>> +        VNInfo *VNI2 = *VI;
>> +        if (VNI2->isUnused())
>> +          continue;
>> +        if (!OrigLI.containsOneValue() &&
>> +            OrigLI.getVNInfoAt(VNI2->def) != OrigVNI)
>> +          continue;
>> +        if (VNI2->isPHIDef() && VNI2->def != OrigVNI->def)
>> +          PHIs.push_back(VNI2);
>> +        else
>> +          NonPHIs.push_back(VNI2);
>> +      }
>> +      DEBUG(dbgs() << "split phi value, checking " << PHIs.size()
>> +                   << " phi-defs, and " << NonPHIs.size()
>> +                   << " non-phi/orig defs\n");
>> +
>> +      // Create entries for all the PHIs.  Don't add them to the
>> worklist, we
>> +      // are processing all of them in one go here.
>> +      for (VNInfo *PHI : PHIs)
>> +        SibValues.insert(std::make_pair(PHI, SibValueInfo(Reg, PHI)));
>> +
>> +      // Add every PHI as a dependent of all the non-PHIs.
>> +      for (VNInfo *NonPHI : NonPHIs) {
>> +        // Known value? Try an insertion.
>> +        std::tie(SVI, Inserted) =
>> +          SibValues.insert(std::make_pair(NonPHI, SibValueInfo(Reg,
>> NonPHI)));
>> +        // Add all the PHIs as dependents of NonPHI.
>> +        SVI->second.Deps.insert(SVI->second.Deps.end(), PHIs.begin(),
>> +                                PHIs.end());
>> +        // This is the first time we see NonPHI, add it to the worklist.
>> +        if (Inserted)
>> +          WorkList.push_back(std::make_pair(Reg, NonPHI));
>> +        else
>> +          // Propagate to all inserted PHIs, not just VNI.
>> +          propagateSiblingValue(SVI);
>> +      }
>> +
>> +      // Next work list item.
>> +      continue;
>> +    }
>> +
>> +    MachineInstr *MI = LIS.getInstructionFromIndex(VNI->def);
>> +    assert(MI && "Missing def");
>> +
>> +    // Trace through sibling copies.
>> +    if (unsigned SrcReg = isFullCopyOf(MI, Reg)) {
>> +      if (isSibling(SrcReg)) {
>> +        LiveInterval &SrcLI = LIS.getInterval(SrcReg);
>> +        LiveQueryResult SrcQ = SrcLI.Query(VNI->def);
>> +        assert(SrcQ.valueIn() && "Copy from non-existing value");
>> +        // Check if this COPY kills its source.
>> +        SVI->second.KillsSource = SrcQ.isKill();
>> +        VNInfo *SrcVNI = SrcQ.valueIn();
>> +        DEBUG(dbgs() << "copy of " << PrintReg(SrcReg) << ':'
>> +                     << SrcVNI->id << '@' << SrcVNI->def
>> +                     << " kill=" << unsigned(SVI->second.KillsSource) <<
>> '\n');
>> +        // Known sibling source value? Try an insertion.
>> +        std::tie(SVI, Inserted) = SibValues.insert(
>> +            std::make_pair(SrcVNI, SibValueInfo(SrcReg, SrcVNI)));
>> +        // This is the first time we see Src, add it to the worklist.
>> +        if (Inserted)
>> +          WorkList.push_back(std::make_pair(SrcReg, SrcVNI));
>> +        propagateSiblingValue(SVI, VNI);
>> +        // Next work list item.
>> +        continue;
>> +      }
>> +    }
>> +
>> +    // Track reachable reloads.
>> +    SVI->second.DefMI = MI;
>> +    SVI->second.SpillMBB = MI->getParent();
>> +    int FI;
>> +    if (Reg == TII.isLoadFromStackSlot(MI, FI) && FI == StackSlot) {
>> +      DEBUG(dbgs() << "reload\n");
>> +      propagateSiblingValue(SVI);
>> +      // Next work list item.
>> +      continue;
>> +    }
>> +
>> +    // Potential remat candidate.
>> +    DEBUG(dbgs() << "def " << *MI);
>> +    SVI->second.AllDefsAreReloads = false;
>> +    propagateSiblingValue(SVI);
>> +  } while (!WorkList.empty());
>> +
>> +  // Look up the value we were looking for.  We already did this lookup
>> at the
>> +  // top of the function, but SibValues may have been invalidated.
>> +  SVI = SibValues.find(UseVNI);
>> +  assert(SVI != SibValues.end() && "Didn't compute requested info");
>> +  DEBUG(dbgs() << "  traced to:\t" << SVI->second);
>> +  return SVI->second.DefMI;
>> +}
>> +
>> +/// analyzeSiblingValues - Trace values defined by sibling copies back to
>> +/// something that isn't a sibling copy.
>>  ///
>> -bool InlineSpiller::hoistSpillInsideBB(LiveInterval &SpillLI,
>> -                                       MachineInstr &CopyMI) {
>> +/// Keep track of values that may be rematerializable.
>> +void InlineSpiller::analyzeSiblingValues() {
>> +  SibValues.clear();
>> +
>> +  // No siblings at all?
>> +  if (Edit->getReg() == Original)
>> +    return;
>> +
>> +  LiveInterval &OrigLI = LIS.getInterval(Original);
>> +  for (unsigned Reg : RegsToSpill) {
>> +    LiveInterval &LI = LIS.getInterval(Reg);
>> +    for (LiveInterval::const_vni_iterator VI = LI.vni_begin(),
>> +         VE = LI.vni_end(); VI != VE; ++VI) {
>> +      VNInfo *VNI = *VI;
>> +      if (VNI->isUnused())
>> +        continue;
>> +      MachineInstr *DefMI = nullptr;
>> +      if (!VNI->isPHIDef()) {
>> +       DefMI = LIS.getInstructionFromIndex(VNI->def);
>> +       assert(DefMI && "No defining instruction");
>> +      }
>> +      // Check possible sibling copies.
>> +      if (VNI->isPHIDef() || DefMI->isCopy()) {
>> +        VNInfo *OrigVNI = OrigLI.getVNInfoAt(VNI->def);
>> +        assert(OrigVNI && "Def outside original live range");
>> +        if (OrigVNI->def != VNI->def)
>> +          DefMI = traceSiblingValue(Reg, VNI, OrigVNI);
>> +      }
>> +      if (DefMI && Edit->checkRematerializable(VNI, DefMI, AA)) {
>> +        DEBUG(dbgs() << "Value " << PrintReg(Reg) << ':' << VNI->id <<
>> '@'
>> +                     << VNI->def << " may remat from " << *DefMI);
>> +      }
>> +    }
>> +  }
>> +}
>> +
>> +/// hoistSpill - Given a sibling copy that defines a value to be spilled,
>> insert
>> +/// a spill at a better location.
>> +bool InlineSpiller::hoistSpill(LiveInterval &SpillLI, MachineInstr
>> &CopyMI) {
>>    SlotIndex Idx = LIS.getInstructionIndex(CopyMI);
>> -#ifndef NDEBUG
>>    VNInfo *VNI = SpillLI.getVNInfoAt(Idx.getRegSlot());
>>    assert(VNI && VNI->def == Idx.getRegSlot() && "Not defined by copy");
>> -#endif
>> -  unsigned SrcReg = CopyMI.getOperand(1).getReg();
>> -  LiveInterval &SrcLI = LIS.getInterval(SrcReg);
>> -  VNInfo *SrcVNI = SrcLI.getVNInfoAt(Idx);
>> -  LiveQueryResult SrcQ = SrcLI.Query(Idx);
>> -  MachineBasicBlock *DefMBB = LIS.getMBBFromIndex(SrcVNI->def);
>> -  if (DefMBB != CopyMI.getParent() || !SrcQ.isKill())
>> +  SibValueMap::iterator I = SibValues.find(VNI);
>> +  if (I == SibValues.end())
>> +    return false;
>> +
>> +  const SibValueInfo &SVI = I->second;
>> +
>> +  // Let the normal folding code deal with the boring case.
>> +  if (!SVI.AllDefsAreReloads && SVI.SpillVNI == VNI)
>> +    return false;
>> +
>> +  // SpillReg may have been deleted by remat and DCE.
>> +  if (!LIS.hasInterval(SVI.SpillReg)) {
>> +    DEBUG(dbgs() << "Stale interval: " << PrintReg(SVI.SpillReg) <<
>> '\n');
>> +    SibValues.erase(I);
>> +    return false;
>> +  }
>> +
>> +  LiveInterval &SibLI = LIS.getInterval(SVI.SpillReg);
>> +  if (!SibLI.containsValue(SVI.SpillVNI)) {
>> +    DEBUG(dbgs() << "Stale value: " << PrintReg(SVI.SpillReg) << '\n');
>> +    SibValues.erase(I);
>>      return false;
>> +  }
>>
>>    // Conservatively extend the stack slot range to the range of the
>> original
>>    // value. We may be able to do better with stack slot coloring by being
>> more
>> @@ -364,29 +719,35 @@ bool InlineSpiller::hoistSpillInsideBB(L
>>    DEBUG(dbgs() << "\tmerged orig valno " << OrigVNI->id << ": "
>>                 << *StackInt << '\n');
>>
>> -  // We are going to spill SrcVNI immediately after its def, so clear out
>> +  // Already spilled everywhere.
>> +  if (SVI.AllDefsAreReloads) {
>> +    DEBUG(dbgs() << "\tno spill needed: " << SVI);
>> +    ++NumOmitReloadSpill;
>> +    return true;
>> +  }
>> +  // We are going to spill SVI.SpillVNI immediately after its def, so
>> clear out
>>    // any later spills of the same value.
>> -  eliminateRedundantSpills(SrcLI, SrcVNI);
>> +  eliminateRedundantSpills(SibLI, SVI.SpillVNI);
>>
>> -  MachineBasicBlock *MBB = LIS.getMBBFromIndex(SrcVNI->def);
>> +  MachineBasicBlock *MBB = LIS.getMBBFromIndex(SVI.SpillVNI->def);
>>    MachineBasicBlock::iterator MII;
>> -  if (SrcVNI->isPHIDef())
>> +  if (SVI.SpillVNI->isPHIDef())
>>      MII = MBB->SkipPHIsAndLabels(MBB->begin());
>>    else {
>> -    MachineInstr *DefMI = LIS.getInstructionFromIndex(SrcVNI->def);
>> +    MachineInstr *DefMI = LIS.getInstructionFromIndex(SVI.SpillVNI->def);
>>      assert(DefMI && "Defining instruction disappeared");
>>      MII = DefMI;
>>      ++MII;
>>    }
>>    // Insert spill without kill flag immediately after def.
>> -  TII.storeRegToStackSlot(*MBB, MII, SrcReg, false, StackSlot,
>> -                          MRI.getRegClass(SrcReg), &TRI);
>> +  TII.storeRegToStackSlot(*MBB, MII, SVI.SpillReg, false, StackSlot,
>> +                          MRI.getRegClass(SVI.SpillReg), &TRI);
>>    --MII; // Point to store instruction.
>>    LIS.InsertMachineInstrInMaps(*MII);
>> -  DEBUG(dbgs() << "\thoisted: " << SrcVNI->def << '\t' << *MII);
>> +  DEBUG(dbgs() << "\thoisted: " << SVI.SpillVNI->def << '\t' << *MII);
>>
>> -  HSpiller.addToMergeableSpills(&(*MII), StackSlot, Original);
>>    ++NumSpills;
>> +  ++NumHoists;
>>    return true;
>>  }
>>
>> @@ -444,8 +805,7 @@ void InlineSpiller::eliminateRedundantSp
>>          MI->setDesc(TII.get(TargetOpcode::KILL));
>>          DeadDefs.push_back(MI);
>>          ++NumSpillsRemoved;
>> -        if (HSpiller.rmFromMergeableSpills(MI, StackSlot))
>> -          --NumSpills;
>> +        --NumSpills;
>>        }
>>      }
>>    } while (!WorkList.empty());
>> @@ -516,12 +876,12 @@ bool InlineSpiller::reMaterializeFor(Liv
>>    if (SnippetCopies.count(&MI))
>>      return false;
>>
>> -  LiveInterval &OrigLI = LIS.getInterval(Original);
>> -  VNInfo *OrigVNI = OrigLI.getVNInfoAt(UseIdx);
>> +  // Use an OrigVNI from traceSiblingValue when ParentVNI is a sibling
>> copy.
>>    LiveRangeEdit::Remat RM(ParentVNI);
>> -  RM.OrigMI = LIS.getInstructionFromIndex(OrigVNI->def);
>> -
>> -  if (!Edit->canRematerializeAt(RM, OrigVNI, UseIdx, false)) {
>> +  SibValueMap::const_iterator SibI = SibValues.find(ParentVNI);
>> +  if (SibI != SibValues.end())
>> +    RM.OrigMI = SibI->second.DefMI;
>> +  if (!Edit->canRematerializeAt(RM, UseIdx, false)) {
>>      markValueUsed(&VirtReg, ParentVNI);
>>      DEBUG(dbgs() << "\tcannot remat for " << UseIdx << '\t' << MI);
>>      return false;
>> @@ -571,6 +931,7 @@ bool InlineSpiller::reMaterializeFor(Liv
>>  /// reMaterializeAll - Try to rematerialize as many uses as possible,
>>  /// and trim the live ranges after.
>>  void InlineSpiller::reMaterializeAll() {
>> +  // analyzeSiblingValues has already tested all relevant defining
>> instructions.
>>    if (!Edit->anyRematerializable(AA))
>>      return;
>>
>> @@ -656,9 +1017,6 @@ bool InlineSpiller::coalesceStackAccess(
>>    if (InstrReg != Reg || FI != StackSlot)
>>      return false;
>>
>> -  if (!IsLoad)
>> -    HSpiller.rmFromMergeableSpills(MI, StackSlot);
>> -
>>    DEBUG(dbgs() << "Coalescing stack access: " << *MI);
>>    LIS.RemoveMachineInstrFromMaps(*MI);
>>    MI->eraseFromParent();
>> @@ -783,9 +1141,6 @@ foldMemoryOperand(ArrayRef<std::pair<Mac
>>      LIS.removePhysRegDefAt(Reg, Idx);
>>    }
>>
>> -  int FI;
>> -  if (TII.isStoreToStackSlot(MI, FI) &&
>> HSpiller.rmFromMergeableSpills(MI, FI))
>> -    --NumSpills;
>>    LIS.ReplaceMachineInstrInMaps(*MI, *FoldMI);
>>    MI->eraseFromParent();
>>
>> @@ -811,10 +1166,9 @@ foldMemoryOperand(ArrayRef<std::pair<Mac
>>
>>    if (!WasCopy)
>>      ++NumFolded;
>> -  else if (Ops.front().second == 0) {
>> +  else if (Ops.front().second == 0)
>>      ++NumSpills;
>> -    HSpiller.addToMergeableSpills(FoldMI, StackSlot, Original);
>> -  } else
>> +  else
>>      ++NumReloads;
>>    return true;
>>  }
>> @@ -849,7 +1203,6 @@ void InlineSpiller::insertSpill(unsigned
>>    DEBUG(dumpMachineInstrRangeWithSlotIndex(std::next(MI), MIS.end(), LIS,
>>                                             "spill"));
>>    ++NumSpills;
>> -  HSpiller.addToMergeableSpills(std::next(MI), StackSlot, Original);
>>  }
>>
>>  /// spillAroundUses - insert spill code around each use of Reg.
>> @@ -913,7 +1266,8 @@ void InlineSpiller::spillAroundUses(unsi
>>          continue;
>>        }
>>        if (RI.Writes) {
>> -        if (hoistSpillInsideBB(OldLI, *MI)) {
>> +        // Hoist the spill of a sib-reg copy.
>> +        if (hoistSpill(OldLI, *MI)) {
>>            // This COPY is now dead, the value is already in the stack
>> slot.
>>            MI->getOperand(0).setIsDead();
>>            DeadDefs.push_back(MI);
>> @@ -1026,6 +1380,7 @@ void InlineSpiller::spill(LiveRangeEdit
>>    assert(DeadDefs.empty() && "Previous spill didn't remove dead defs");
>>
>>    collectRegsToSpill();
>> +  analyzeSiblingValues();
>>    reMaterializeAll();
>>
>>    // Remat may handle everything.
>> @@ -1034,394 +1389,3 @@ void InlineSpiller::spill(LiveRangeEdit
>>
>>    Edit->calculateRegClassAndHint(MF, Loops, MBFI);
>>  }
>> -
>> -/// Optimizations after all the reg selections and spills are done.
>> -///
>> -void InlineSpiller::postOptimization() {
>> -  SmallVector<unsigned, 4> NewVRegs;
>> -  LiveRangeEdit LRE(nullptr, NewVRegs, MF, LIS, &VRM, nullptr);
>> -  HSpiller.hoistAllSpills(LRE);
>> -  assert(NewVRegs.size() == 0 &&
>> -         "No new vregs should be generated in hoistAllSpills");
>> -}
>> -
>> -/// When a spill is inserted, add the spill to MergeableSpills map.
>> -///
>> -void HoistSpillHelper::addToMergeableSpills(MachineInstr *Spill, int
>> StackSlot,
>> -                                           unsigned Original) {
>> -  StackSlotToReg[StackSlot] = Original;
>> -  SlotIndex Idx = LIS.getInstructionIndex(*Spill);
>> -  VNInfo *OrigVNI =
>> LIS.getInterval(Original).getVNInfoAt(Idx.getRegSlot());
>> -  std::pair<int, VNInfo *> MIdx = std::make_pair(StackSlot, OrigVNI);
>> -  MergeableSpills[MIdx].insert(Spill);
>> -}
>> -
>> -/// When a spill is removed, remove the spill from MergeableSpills map.
>> -/// Return true if the spill is removed successfully.
>> -///
>> -bool HoistSpillHelper::rmFromMergeableSpills(MachineInstr *Spill,
>> -                                             int StackSlot) {
>> -  int Original = StackSlotToReg[StackSlot];
>> -  if (!Original)
>> -    return false;
>> -  SlotIndex Idx = LIS.getInstructionIndex(*Spill);
>> -  VNInfo *OrigVNI =
>> LIS.getInterval(Original).getVNInfoAt(Idx.getRegSlot());
>> -  std::pair<int, VNInfo *> MIdx = std::make_pair(StackSlot, OrigVNI);
>> -  return MergeableSpills[MIdx].erase(Spill);
>> -}
>> -
>> -/// Check BB to see if it is a possible target BB to place a hoisted
>> spill,
>> -/// i.e., there should be a living sibling of OrigReg at the insert
>> point.
>> -///
>> -bool HoistSpillHelper::isSpillCandBB(unsigned OrigReg, VNInfo &OrigVNI,
>> -                                     MachineBasicBlock &BB, unsigned
>> &LiveReg) {
>> -  SlotIndex Idx;
>> -  MachineBasicBlock::iterator MI = BB.getFirstTerminator();
>> -  if (MI != BB.end())
>> -    Idx = LIS.getInstructionIndex(*MI);
>> -  else
>> -    Idx = LIS.getMBBEndIdx(&BB).getPrevSlot();
>> -  SmallSetVector<unsigned, 16> &Siblings = Virt2SiblingsMap[OrigReg];
>> -  assert((LIS.getInterval(OrigReg)).getVNInfoAt(Idx) == &OrigVNI &&
>> -         "Unexpected VNI");
>> -
>> -  for (auto const SibReg : Siblings) {
>> -    LiveInterval &LI = LIS.getInterval(SibReg);
>> -    VNInfo *VNI = LI.getVNInfoAt(Idx);
>> -    if (VNI) {
>> -      LiveReg = SibReg;
>> -      return true;
>> -    }
>> -  }
>> -  return false;
>> -}
>> -
>> -/// Remove redundent spills in the same BB. Save those redundent spills
>> in
>> -/// SpillsToRm, and save the spill to keep and its BB in SpillBBToSpill
>> map.
>> -///
>> -void HoistSpillHelper::rmRedundantSpills(
>> -    SmallPtrSet<MachineInstr *, 16> &Spills,
>> -    SmallVectorImpl<MachineInstr *> &SpillsToRm,
>> -    DenseMap<MachineDomTreeNode *, MachineInstr *> &SpillBBToSpill) {
>> -  // For each spill saw, check SpillBBToSpill[] and see if its BB already
>> has
>> -  // another spill inside. If a BB contains more than one spill, only
>> keep the
>> -  // earlier spill with smaller SlotIndex.
>> -  for (const auto CurrentSpill : Spills) {
>> -    MachineBasicBlock *Block = CurrentSpill->getParent();
>> -    MachineDomTreeNode *Node = MDT.DT->getNode(Block);
>> -    MachineInstr *PrevSpill = SpillBBToSpill[Node];
>> -    if (PrevSpill) {
>> -      SlotIndex PIdx = LIS.getInstructionIndex(*PrevSpill);
>> -      SlotIndex CIdx = LIS.getInstructionIndex(*CurrentSpill);
>> -      MachineInstr *SpillToRm = (CIdx > PIdx) ? CurrentSpill : PrevSpill;
>> -      MachineInstr *SpillToKeep = (CIdx > PIdx) ? PrevSpill :
>> CurrentSpill;
>> -      SpillsToRm.push_back(SpillToRm);
>> -      SpillBBToSpill[MDT.DT->getNode(Block)] = SpillToKeep;
>> -    } else {
>> -      SpillBBToSpill[MDT.DT->getNode(Block)] = CurrentSpill;
>> -    }
>> -  }
>> -  for (const auto SpillToRm : SpillsToRm)
>> -    Spills.erase(SpillToRm);
>> -}
>> -
>> -/// Starting from \p Root find a top-down traversal order of the
>> dominator
>> -/// tree to visit all basic blocks containing the elements of \p Spills.
>> -/// Redundant spills will be found and put into \p SpillsToRm at the same
>> -/// time. \p SpillBBToSpill will be populated as part of the process and
>> -/// maps a basic block to the first store occurring in the basic block.
>> -/// \post SpillsToRm.union(Spills at post) == Spills at pre
>> -///
>> -void HoistSpillHelper::getVisitOrders(
>> -    MachineBasicBlock *Root, SmallPtrSet<MachineInstr *, 16> &Spills,
>> -    SmallVectorImpl<MachineDomTreeNode *> &Orders,
>> -    SmallVectorImpl<MachineInstr *> &SpillsToRm,
>> -    DenseMap<MachineDomTreeNode *, unsigned> &SpillsToKeep,
>> -    DenseMap<MachineDomTreeNode *, MachineInstr *> &SpillBBToSpill) {
>> -  // The set contains all the possible BB nodes to which we may hoist
>> -  // original spills.
>> -  SmallPtrSet<MachineDomTreeNode *, 8> WorkSet;
>> -  // Save the BB nodes on the path from the first BB node containing
>> -  // non-redundent spill to the Root node.
>> -  SmallPtrSet<MachineDomTreeNode *, 8> NodesOnPath;
>> -  // All the spills to be hoisted must originate from a single def
>> instruction
>> -  // to the OrigReg. It means the def instruction should dominate all the
>> spills
>> -  // to be hoisted. We choose the BB where the def instruction is located
>> as
>> -  // the Root.
>> -  MachineDomTreeNode *RootIDomNode = MDT[Root]->getIDom();
>> -  // For every node on the dominator tree with spill, walk up on the
>> dominator
>> -  // tree towards the Root node until it is reached. If there is other
>> node
>> -  // containing spill in the middle of the path, the previous spill saw
>> will
>> -  // be redundent and the node containing it will be removed. All the
>> nodes on
>> -  // the path starting from the first node with non-redundent spill to
>> the Root
>> -  // node will be added to the WorkSet, which will contain all the
>> possible
>> -  // locations where spills may be hoisted to after the loop below is
>> done.
>> -  for (const auto Spill : Spills) {
>> -    MachineBasicBlock *Block = Spill->getParent();
>> -    MachineDomTreeNode *Node = MDT[Block];
>> -    MachineInstr *SpillToRm = nullptr;
>> -    while (Node != RootIDomNode) {
>> -      // If Node dominates Block, and it already contains a spill, the
>> spill in
>> -      // Block will be redundent.
>> -      if (Node != MDT[Block] && SpillBBToSpill[Node]) {
>> -        SpillToRm = SpillBBToSpill[MDT[Block]];
>> -        break;
>> -        /// If we see the Node already in WorkSet, the path from the Node
>> to
>> -        /// the Root node must already be traversed by another spill.
>> -        /// Then no need to repeat.
>> -      } else if (WorkSet.count(Node)) {
>> -        break;
>> -      } else {
>> -        NodesOnPath.insert(Node);
>> -      }
>> -      Node = Node->getIDom();
>> -    }
>> -    if (SpillToRm) {
>> -      SpillsToRm.push_back(SpillToRm);
>> -    } else {
>> -      // Add a BB containing the original spills to SpillsToKeep -- i.e.,
>> -      // set the initial status before hoisting start. The value of BBs
>> -      // containing original spills is set to 0, in order to descriminate
>> -      // with BBs containing hoisted spills which will be inserted to
>> -      // SpillsToKeep later during hoisting.
>> -      SpillsToKeep[MDT[Block]] = 0;
>> -      WorkSet.insert(NodesOnPath.begin(), NodesOnPath.end());
>> -    }
>> -    NodesOnPath.clear();
>> -  }
>> -
>> -  // Sort the nodes in WorkSet in top-down order and save the nodes
>> -  // in Orders. Orders will be used for hoisting in runHoistSpills.
>> -  unsigned idx = 0;
>> -  Orders.push_back(MDT.DT->getNode(Root));
>> -  do {
>> -    MachineDomTreeNode *Node = Orders[idx++];
>> -    const std::vector<MachineDomTreeNode *> &Children =
>> Node->getChildren();
>> -    unsigned NumChildren = Children.size();
>> -    for (unsigned i = 0; i != NumChildren; ++i) {
>> -      MachineDomTreeNode *Child = Children[i];
>> -      if (WorkSet.count(Child))
>> -        Orders.push_back(Child);
>> -    }
>> -  } while (idx != Orders.size());
>> -  assert(Orders.size() == WorkSet.size() &&
>> -         "Orders have different size with WorkSet");
>> -
>> -#ifndef NDEBUG
>> -  DEBUG(dbgs() << "Orders size is " << Orders.size() << "\n");
>> -  SmallVector<MachineDomTreeNode *, 32>::reverse_iterator RIt =
>> Orders.rbegin();
>> -  for (; RIt != Orders.rend(); RIt++)
>> -    DEBUG(dbgs() << "BB" << (*RIt)->getBlock()->getNumber() << ",");
>> -  DEBUG(dbgs() << "\n");
>> -#endif
>> -}
>> -
>> -/// Try to hoist spills according to BB hotness. The spills to removed
>> will
>> -/// be saved in \p SpillsToRm. The spills to be inserted will be saved in
>> -/// \p SpillsToIns.
>> -///
>> -void HoistSpillHelper::runHoistSpills(
>> -    unsigned OrigReg, VNInfo &OrigVNI, SmallPtrSet<MachineInstr *, 16>
>> &Spills,
>> -    SmallVectorImpl<MachineInstr *> &SpillsToRm,
>> -    DenseMap<MachineBasicBlock *, unsigned> &SpillsToIns) {
>> -  // Visit order of dominator tree nodes.
>> -  SmallVector<MachineDomTreeNode *, 32> Orders;
>> -  // SpillsToKeep contains all the nodes where spills are to be inserted
>> -  // during hoisting. If the spill to be inserted is an original spill
>> -  // (not a hoisted one), the value of the map entry is 0. If the spill
>> -  // is a hoisted spill, the value of the map entry is the VReg to be
>> used
>> -  // as the source of the spill.
>> -  DenseMap<MachineDomTreeNode *, unsigned> SpillsToKeep;
>> -  // Map from BB to the first spill inside of it.
>> -  DenseMap<MachineDomTreeNode *, MachineInstr *> SpillBBToSpill;
>> -
>> -  rmRedundantSpills(Spills, SpillsToRm, SpillBBToSpill);
>> -
>> -  MachineBasicBlock *Root = LIS.getMBBFromIndex(OrigVNI.def);
>> -  getVisitOrders(Root, Spills, Orders, SpillsToRm, SpillsToKeep,
>> -                 SpillBBToSpill);
>> -
>> -  // SpillsInSubTree keeps the map from a dom tree node to a pair of
>> -  // nodes set and the cost of all the spills inside those nodes.
>> -  // The nodes set are the locations where spills are to be inserted
>> -  // in the subtree of current node.
>> -  typedef std::pair<SmallPtrSet<MachineDomTreeNode *, 16>,
>> BlockFrequency>
>> -      NodesCostPair;
>> -  DenseMap<MachineDomTreeNode *, NodesCostPair> SpillsInSubTreeMap;
>> -  // Iterate Orders set in reverse order, which will be a bottom-up order
>> -  // in the dominator tree. Once we visit a dom tree node, we know its
>> -  // children have already been visited and the spill locations in the
>> -  // subtrees of all the children have been determined.
>> -  SmallVector<MachineDomTreeNode *, 32>::reverse_iterator RIt =
>> Orders.rbegin();
>> -  for (; RIt != Orders.rend(); RIt++) {
>> -    MachineBasicBlock *Block = (*RIt)->getBlock();
>> -    SmallPtrSet<MachineDomTreeNode *, 16> &SpillsInSubTree =
>> -        SpillsInSubTreeMap[*RIt].first;
>> -    // Total spill costs inside the sub tree.
>> -    BlockFrequency &SubTreeCost = SpillsInSubTreeMap[*RIt].second;
>> -
>> -    // If Block contains an original spill, simply continue.
>> -    if (SpillsToKeep.find(*RIt) != SpillsToKeep.end() &&
>> !SpillsToKeep[*RIt]) {
>> -      SpillsInSubTree.insert(*RIt);
>> -      SubTreeCost = MBFI.getBlockFreq(Block);
>> -      continue;
>> -    }
>> -
>> -    // Collect spills in subtree of current node (*RIt) to
>> -    // SpillsInSubTree.
>> -    const std::vector<MachineDomTreeNode *> &Children =
>> (*RIt)->getChildren();
>> -    unsigned NumChildren = Children.size();
>> -    for (unsigned i = 0; i != NumChildren; ++i) {
>> -      MachineDomTreeNode *Child = Children[i];
>> -      SpillsInSubTree.insert(SpillsInSubTreeMap[Child].first.begin(),
>> -                             SpillsInSubTreeMap[Child].first.end());
>> -      SubTreeCost += SpillsInSubTreeMap[Child].second;
>> -      SpillsInSubTreeMap.erase(Child);
>> -    }
>> -
>> -    // No spills in subtree, simply continue.
>> -    if (SpillsInSubTree.empty())
>> -      continue;
>> -
>> -    // Check whether Block is a possible candidate to insert spill.
>> -    unsigned LiveReg = 0;
>> -    if (!isSpillCandBB(OrigReg, OrigVNI, *Block, LiveReg))
>> -      continue;
>> -
>> -    // If there are multiple spills that could be merged, bias a little
>> -    // to hoist the spill.
>> -    BranchProbability MarginProb = (SpillsInSubTree.size() > 1)
>> -                                       ? BranchProbability(9, 10)
>> -                                       : BranchProbability(1, 1);
>> -    if (SubTreeCost > MBFI.getBlockFreq(Block) * MarginProb) {
>> -      // Hoist: Move spills to current Block.
>> -      for (const auto SpillBB : SpillsInSubTree) {
>> -        // When SpillBB is a BB contains original spill, insert the spill
>> -        // to SpillsToRm.
>> -        if (SpillsToKeep.find(SpillBB) != SpillsToKeep.end() &&
>> -            !SpillsToKeep[SpillBB]) {
>> -          MachineInstr *SpillToRm = SpillBBToSpill[SpillBB];
>> -          SpillsToRm.push_back(SpillToRm);
>> -        }
>> -        // SpillBB will not contain spill anymore, remove it from
>> SpillsToKeep.
>> -        SpillsToKeep.erase(SpillBB);
>> -      }
>> -      // Current Block is the BB containing the new hoisted spill. Add it
>> to
>> -      // SpillsToKeep. LiveReg is the source of the new spill.
>> -      SpillsToKeep[*RIt] = LiveReg;
>> -      DEBUG({
>> -        dbgs() << "spills in BB: ";
>> -        for (const auto Rspill : SpillsInSubTree)
>> -          dbgs() << Rspill->getBlock()->getNumber() << " ";
>> -        dbgs() << "were promoted to BB" <<
>> (*RIt)->getBlock()->getNumber()
>> -               << "\n";
>> -      });
>> -      SpillsInSubTree.clear();
>> -      SpillsInSubTree.insert(*RIt);
>> -      SubTreeCost = MBFI.getBlockFreq(Block);
>> -    }
>> -  }
>> -  // For spills in SpillsToKeep with LiveReg set (i.e., not original
>> spill),
>> -  // save them to SpillsToIns.
>> -  for (const auto Ent : SpillsToKeep) {
>> -    if (Ent.second)
>> -      SpillsToIns[Ent.first->getBlock()] = Ent.second;
>> -  }
>> -}
>> -
>> -/// For spills with equal values, remove redundent spills and hoist the
>> left
>> -/// to less hot spots.
>> -///
>> -/// Spills with equal values will be collected into the same set in
>> -/// MergeableSpills when spill is inserted. These equal spills are
>> originated
>> -/// from the same define instruction and are dominated by the
>> instruction.
>> -/// Before hoisting all the equal spills, redundent spills inside in the
>> same
>> -/// BB is first marked to be deleted. Then starting from spills left,
>> walk up
>> -/// on the dominator tree towards the Root node where the define
>> instruction
>> -/// is located, mark the dominated spills to be deleted along the way and
>> -/// collect the BB nodes on the path from non-dominated spills to the
>> define
>> -/// instruction into a WorkSet. The nodes in WorkSet are the candidate
>> places
>> -/// where we consider to hoist the spills. We iterate the WorkSet in
>> bottom-up
>> -/// order, and for each node, we will decide whether to hoist spills
>> inside
>> -/// its subtree to that node. In this way, we can get benefit locally
>> even if
>> -/// hoisting all the equal spills to one cold place is impossible.
>> -///
>> -void HoistSpillHelper::hoistAllSpills(LiveRangeEdit &Edit) {
>> -  // Save the mapping between stackslot and its original reg.
>> -  DenseMap<int, unsigned> SlotToOrigReg;
>> -  for (unsigned i = 0, e = MRI.getNumVirtRegs(); i != e; ++i) {
>> -    unsigned Reg = TargetRegisterInfo::index2VirtReg(i);
>> -    int Slot = VRM.getStackSlot(Reg);
>> -    if (Slot != VirtRegMap::NO_STACK_SLOT)
>> -      SlotToOrigReg[Slot] = VRM.getOriginal(Reg);
>> -    unsigned Original = VRM.getPreSplitReg(Reg);
>> -    if (!MRI.def_empty(Reg))
>> -      Virt2SiblingsMap[Original].insert(Reg);
>> -  }
>> -
>> -  // Each entry in MergeableSpills contains a spill set with equal
>> values.
>> -  for (auto &Ent : MergeableSpills) {
>> -    int Slot = Ent.first.first;
>> -    unsigned OrigReg = SlotToOrigReg[Slot];
>> -    VNInfo *OrigVNI = Ent.first.second;
>> -    SmallPtrSet<MachineInstr *, 16> &EqValSpills = Ent.second;
>> -    if (Ent.second.empty())
>> -      continue;
>> -
>> -    DEBUG({
>> -      dbgs() << "\nFor Slot" << Slot << " and VN" << OrigVNI->id << ":\n"
>> -             << "Equal spills in BB: ";
>> -      for (const auto spill : EqValSpills)
>> -        dbgs() << spill->getParent()->getNumber() << " ";
>> -      dbgs() << "\n";
>> -    });
>> -
>> -    // SpillsToRm is the spill set to be removed from EqValSpills.
>> -    SmallVector<MachineInstr *, 16> SpillsToRm;
>> -    // SpillsToIns is the spill set to be newly inserted after hoisting.
>> -    DenseMap<MachineBasicBlock *, unsigned> SpillsToIns;
>> -
>> -    runHoistSpills(OrigReg, *OrigVNI, EqValSpills, SpillsToRm,
>> SpillsToIns);
>> -
>> -    DEBUG({
>> -      dbgs() << "Finally inserted spills in BB: ";
>> -      for (const auto Ispill : SpillsToIns)
>> -        dbgs() << Ispill.first->getNumber() << " ";
>> -      dbgs() << "\nFinally removed spills in BB: ";
>> -      for (const auto Rspill : SpillsToRm)
>> -        dbgs() << Rspill->getParent()->getNumber() << " ";
>> -      dbgs() << "\n";
>> -    });
>> -
>> -    // Stack live range update.
>> -    LiveInterval &StackIntvl = LSS.getInterval(Slot);
>> -    if (!SpillsToIns.empty() || !SpillsToRm.empty()) {
>> -      LiveInterval &OrigLI = LIS.getInterval(OrigReg);
>> -      StackIntvl.MergeValueInAsValue(OrigLI, OrigVNI,
>> -                                     StackIntvl.getValNumInfo(0));
>> -    }
>> -
>> -    // Insert hoisted spills.
>> -    for (auto const Insert : SpillsToIns) {
>> -      MachineBasicBlock *BB = Insert.first;
>> -      unsigned LiveReg = Insert.second;
>> -      MachineBasicBlock::iterator MI = BB->getFirstTerminator();
>> -      TII.storeRegToStackSlot(*BB, MI, LiveReg, false, Slot,
>> -                              MRI.getRegClass(LiveReg), &TRI);
>> -      LIS.InsertMachineInstrRangeInMaps(std::prev(MI), MI);
>> -      ++NumSpills;
>> -    }
>> -
>> -    // Remove redundent spills or change them to dead instructions.
>> -    NumSpills -= SpillsToRm.size();
>> -    for (auto const RMEnt : SpillsToRm) {
>> -      RMEnt->setDesc(TII.get(TargetOpcode::KILL));
>> -      for (unsigned i = RMEnt->getNumOperands(); i; --i) {
>> -        MachineOperand &MO = RMEnt->getOperand(i - 1);
>> -        if (MO.isReg() && MO.isImplicit() && MO.isDef() && !MO.isDead())
>> -          RMEnt->RemoveOperand(i - 1);
>> -      }
>> -    }
>> -    Edit.eliminateDeadDefs(SpillsToRm, None, true);
>> -  }
>> -}
>>
>> Modified: llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/LiveRangeEdit.cpp Mon Apr  4 12:45:03 2016
>> @@ -63,13 +63,10 @@ void LiveRangeEdit::scanRemattable(Alias
>>    for (VNInfo *VNI : getParent().valnos) {
>>      if (VNI->isUnused())
>>        continue;
>> -    unsigned Original = VRM->getOriginal(getReg());
>> -    LiveInterval &OrigLI = LIS.getInterval(Original);
>> -    VNInfo *OrigVNI = OrigLI.getVNInfoAt(VNI->def);
>> -    MachineInstr *DefMI = LIS.getInstructionFromIndex(OrigVNI->def);
>> +    MachineInstr *DefMI = LIS.getInstructionFromIndex(VNI->def);
>>      if (!DefMI)
>>        continue;
>> -    checkRematerializable(OrigVNI, DefMI, aa);
>> +    checkRematerializable(VNI, DefMI, aa);
>>    }
>>    ScannedRemattable = true;
>>  }
>> @@ -116,18 +113,24 @@ bool LiveRangeEdit::allUsesAvailableAt(c
>>    return true;
>>  }
>>
>> -bool LiveRangeEdit::canRematerializeAt(Remat &RM, VNInfo *OrigVNI,
>> -                                       SlotIndex UseIdx, bool
>> cheapAsAMove) {
>> +bool LiveRangeEdit::canRematerializeAt(Remat &RM,
>> +                                       SlotIndex UseIdx,
>> +                                       bool cheapAsAMove) {
>>    assert(ScannedRemattable && "Call anyRematerializable first");
>>
>>    // Use scanRemattable info.
>> -  if (!Remattable.count(OrigVNI))
>> +  if (!Remattable.count(RM.ParentVNI))
>>      return false;
>>
>>    // No defining instruction provided.
>>    SlotIndex DefIdx;
>> -  assert(RM.OrigMI && "No defining instruction for remattable value");
>> -  DefIdx = LIS.getInstructionIndex(*RM.OrigMI);
>> +  if (RM.OrigMI)
>> +    DefIdx = LIS.getInstructionIndex(*RM.OrigMI);
>> +  else {
>> +    DefIdx = RM.ParentVNI->def;
>> +    RM.OrigMI = LIS.getInstructionFromIndex(DefIdx);
>> +    assert(RM.OrigMI && "No defining instruction for remattable value");
>> +  }
>>
>>    // If only cheap remats were requested, bail out early.
>>    if (cheapAsAMove && !TII.isAsCheapAsAMove(RM.OrigMI))
>> @@ -258,15 +261,6 @@ void LiveRangeEdit::eliminateDeadDef(Mac
>>    // Collect virtual registers to be erased after MI is gone.
>>    SmallVector<unsigned, 8> RegsToErase;
>>    bool ReadsPhysRegs = false;
>> -  bool isOrigDef = false;
>> -  unsigned Dest;
>> -  if (VRM && MI->getOperand(0).isReg()) {
>> -    Dest = MI->getOperand(0).getReg();
>> -    unsigned Original = VRM->getOriginal(Dest);
>> -    LiveInterval &OrigLI = LIS.getInterval(Original);
>> -    VNInfo *OrigVNI = OrigLI.getVNInfoAt(Idx);
>> -    isOrigDef = SlotIndex::isSameInstr(OrigVNI->def, Idx);
>> -  }
>>
>>    // Check for live intervals that may shrink
>>    for (MachineInstr::mop_iterator MOI = MI->operands_begin(),
>> @@ -320,24 +314,11 @@ void LiveRangeEdit::eliminateDeadDef(Mac
>>      }
>>      DEBUG(dbgs() << "Converted physregs to:\t" << *MI);
>>    } else {
>> -    // If the dest of MI is an original reg, don't delete the inst.
>> Replace
>> -    // the dest with a new reg, keep the inst for remat of other
>> siblings.
>> -    // The inst is saved in LiveRangeEdit::DeadRemats and will be deleted
>> -    // after all the allocations of the func are done.
>> -    if (isOrigDef) {
>> -      unsigned NewDest = createFrom(Dest);
>> -      pop_back();
>> -      markDeadRemat(MI);
>> -      const TargetRegisterInfo &TRI = *MRI.getTargetRegisterInfo();
>> -      MI->substituteRegister(Dest, NewDest, 0, TRI);
>> -      MI->getOperand(0).setIsDead(false);
>> -    } else {
>> -      if (TheDelegate)
>> -        TheDelegate->LRE_WillEraseInstruction(MI);
>> -      LIS.RemoveMachineInstrFromMaps(*MI);
>> -      MI->eraseFromParent();
>> -      ++NumDCEDeleted;
>> -    }
>> +    if (TheDelegate)
>> +      TheDelegate->LRE_WillEraseInstruction(MI);
>> +    LIS.RemoveMachineInstrFromMaps(*MI);
>> +    MI->eraseFromParent();
>> +    ++NumDCEDeleted;
>>    }
>>
>>    // Erase any virtregs that are now empty and unused. There may be
>> <undef>
>> @@ -351,9 +332,8 @@ void LiveRangeEdit::eliminateDeadDef(Mac
>>    }
>>  }
>>
>> -void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr *>
>> &Dead,
>> -                                      ArrayRef<unsigned>
>> RegsBeingSpilled,
>> -                                      bool NoSplit) {
>> +void LiveRangeEdit::eliminateDeadDefs(SmallVectorImpl<MachineInstr*>
>> &Dead,
>> +                                      ArrayRef<unsigned>
>> RegsBeingSpilled) {
>>    ToShrinkSet ToShrink;
>>
>>    for (;;) {
>> @@ -375,9 +355,6 @@ void LiveRangeEdit::eliminateDeadDefs(Sm
>>      if (!LIS.shrinkToUses(LI, &Dead))
>>        continue;
>>
>> -    if (NoSplit)
>> -      continue;
>> -
>>      // Don't create new intervals for a register being spilled.
>>      // The new intervals would have to be spilled anyway so its not worth
>> it.
>>      // Also they currently aren't spilled so creating them and not
>> spilling
>>
>> Modified: llvm/trunk/lib/CodeGen/RegAllocBase.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocBase.cpp?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/RegAllocBase.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/RegAllocBase.cpp Mon Apr  4 12:45:03 2016
>> @@ -153,12 +153,3 @@ void RegAllocBase::allocatePhysRegs() {
>>      }
>>    }
>>  }
>> -
>> -void RegAllocBase::postOptimization() {
>> -  spiller().postOptimization();
>> -  for (auto DeadInst : DeadRemats) {
>> -    LIS->RemoveMachineInstrFromMaps(*DeadInst);
>> -    DeadInst->eraseFromParent();
>> -  }
>> -  DeadRemats.clear();
>> -}
>>
>> Modified: llvm/trunk/lib/CodeGen/RegAllocBase.h
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocBase.h?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/RegAllocBase.h (original)
>> +++ llvm/trunk/lib/CodeGen/RegAllocBase.h Mon Apr  4 12:45:03 2016
>> @@ -65,12 +65,6 @@ protected:
>>    LiveRegMatrix *Matrix;
>>    RegisterClassInfo RegClassInfo;
>>
>> -  /// Inst which is a def of an original reg and whose defs are already
>> all
>> -  /// dead after remat is saved in DeadRemats. The deletion of such inst
>> is
>> -  /// postponed till all the allocations are done, so its remat expr is
>> -  /// always available for the remat of all the siblings of the original
>> reg.
>> -  SmallPtrSet<MachineInstr *, 32> DeadRemats;
>> -
>>    RegAllocBase()
>>      : TRI(nullptr), MRI(nullptr), VRM(nullptr), LIS(nullptr),
>> Matrix(nullptr) {}
>>
>> @@ -83,10 +77,6 @@ protected:
>>    // physical register assignments.
>>    void allocatePhysRegs();
>>
>> -  // Include spiller post optimization and removing dead defs left
>> because of
>> -  // rematerialization.
>> -  virtual void postOptimization();
>> -
>>    // Get a temporary reference to a Spiller instance.
>>    virtual Spiller &spiller() = 0;
>>
>>
>> Modified: llvm/trunk/lib/CodeGen/RegAllocBasic.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocBasic.cpp?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/RegAllocBasic.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/RegAllocBasic.cpp Mon Apr  4 12:45:03 2016
>> @@ -199,7 +199,7 @@ bool RABasic::spillInterferences(LiveInt
>>      Matrix->unassign(Spill);
>>
>>      // Spill the extracted interval.
>> -    LiveRangeEdit LRE(&Spill, SplitVRegs, *MF, *LIS, VRM, nullptr,
>> &DeadRemats);
>> +    LiveRangeEdit LRE(&Spill, SplitVRegs, *MF, *LIS, VRM);
>>      spiller().spill(LRE);
>>    }
>>    return true;
>> @@ -258,7 +258,7 @@ unsigned RABasic::selectOrSplit(LiveInte
>>    DEBUG(dbgs() << "spilling: " << VirtReg << '\n');
>>    if (!VirtReg.isSpillable())
>>      return ~0u;
>> -  LiveRangeEdit LRE(&VirtReg, SplitVRegs, *MF, *LIS, VRM, nullptr,
>> &DeadRemats);
>> +  LiveRangeEdit LRE(&VirtReg, SplitVRegs, *MF, *LIS, VRM);
>>    spiller().spill(LRE);
>>
>>    // The live virtual register requesting allocation was spilled, so tell
>> @@ -283,7 +283,6 @@ bool RABasic::runOnMachineFunction(Machi
>>    SpillerInstance.reset(createInlineSpiller(*this, *MF, *VRM));
>>
>>    allocatePhysRegs();
>> -  postOptimization();
>>
>>    // Diagnostic output before rewriting
>>    DEBUG(dbgs() << "Post alloc VirtRegMap:\n" << *VRM << "\n");
>>
>> Modified: llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/RegAllocGreedy.cpp Mon Apr  4 12:45:03 2016
>> @@ -12,6 +12,7 @@
>>  //
>>
>> //===----------------------------------------------------------------------===//
>>
>> +#include "llvm/CodeGen/Passes.h"
>>  #include "AllocationOrder.h"
>>  #include "InterferenceCache.h"
>>  #include "LiveDebugVariables.h"
>> @@ -32,7 +33,6 @@
>>  #include "llvm/CodeGen/MachineFunctionPass.h"
>>  #include "llvm/CodeGen/MachineLoopInfo.h"
>>  #include "llvm/CodeGen/MachineRegisterInfo.h"
>> -#include "llvm/CodeGen/Passes.h"
>>  #include "llvm/CodeGen/RegAllocRegistry.h"
>>  #include "llvm/CodeGen/RegisterClassInfo.h"
>>  #include "llvm/CodeGen/VirtRegMap.h"
>> @@ -44,7 +44,6 @@
>>  #include "llvm/Support/ErrorHandling.h"
>>  #include "llvm/Support/Timer.h"
>>  #include "llvm/Support/raw_ostream.h"
>> -#include "llvm/Target/TargetInstrInfo.h"
>>  #include "llvm/Target/TargetSubtargetInfo.h"
>>  #include <queue>
>>
>> @@ -56,14 +55,14 @@ STATISTIC(NumGlobalSplits, "Number of sp
>>  STATISTIC(NumLocalSplits,  "Number of split local live ranges");
>>  STATISTIC(NumEvicted,      "Number of interferences evicted");
>>
>> -static cl::opt<SplitEditor::ComplementSpillMode> SplitSpillMode(
>> -    "split-spill-mode", cl::Hidden,
>> -    cl::desc("Spill mode for splitting live ranges"),
>> -    cl::values(clEnumValN(SplitEditor::SM_Partition, "default",
>> "Default"),
>> -               clEnumValN(SplitEditor::SM_Size, "size", "Optimize for
>> size"),
>> -               clEnumValN(SplitEditor::SM_Speed, "speed", "Optimize for
>> speed"),
>> -               clEnumValEnd),
>> -    cl::init(SplitEditor::SM_Speed));
>> +static cl::opt<SplitEditor::ComplementSpillMode>
>> +SplitSpillMode("split-spill-mode", cl::Hidden,
>> +  cl::desc("Spill mode for splitting live ranges"),
>> +  cl::values(clEnumValN(SplitEditor::SM_Partition, "default", "Default"),
>> +             clEnumValN(SplitEditor::SM_Size,  "size",  "Optimize for
>> size"),
>> +             clEnumValN(SplitEditor::SM_Speed, "speed", "Optimize for
>> speed"),
>> +             clEnumValEnd),
>> +  cl::init(SplitEditor::SM_Partition));
>>
>>  static cl::opt<unsigned>
>>  LastChanceRecoloringMaxDepth("lcr-max-depth", cl::Hidden,
>> @@ -1466,7 +1465,7 @@ unsigned RAGreedy::doRegionSplit(LiveInt
>>                                   SmallVectorImpl<unsigned> &NewVRegs) {
>>    SmallVector<unsigned, 8> UsedCands;
>>    // Prepare split editor.
>> -  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this,
>> &DeadRemats);
>> +  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
>>    SE->reset(LREdit, SplitSpillMode);
>>
>>    // Assign all edge bundles to the preferred candidate, or NoCand.
>> @@ -1514,7 +1513,7 @@ unsigned RAGreedy::tryBlockSplit(LiveInt
>>    assert(&SA->getParent() == &VirtReg && "Live range wasn't analyzed");
>>    unsigned Reg = VirtReg.reg;
>>    bool SingleInstrs =
>> RegClassInfo.isProperSubClass(MRI->getRegClass(Reg));
>> -  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this,
>> &DeadRemats);
>> +  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
>>    SE->reset(LREdit, SplitSpillMode);
>>    ArrayRef<SplitAnalysis::BlockInfo> UseBlocks = SA->getUseBlocks();
>>    for (unsigned i = 0; i != UseBlocks.size(); ++i) {
>> @@ -1586,7 +1585,7 @@ RAGreedy::tryInstructionSplit(LiveInterv
>>
>>    // Always enable split spill mode, since we're effectively spilling to
>> a
>>    // register.
>> -  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this,
>> &DeadRemats);
>> +  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
>>    SE->reset(LREdit, SplitEditor::SM_Size);
>>
>>    ArrayRef<SlotIndex> Uses = SA->getUseSlots();
>> @@ -1909,7 +1908,7 @@ unsigned RAGreedy::tryLocalSplit(LiveInt
>>                 << '-' << Uses[BestAfter] << ", " << BestDiff
>>                 << ", " << (BestAfter - BestBefore + 1) << " instrs\n");
>>
>> -  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this,
>> &DeadRemats);
>> +  LiveRangeEdit LREdit(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
>>    SE->reset(LREdit);
>>
>>    SE->openIntv();
>> @@ -2552,7 +2551,7 @@ unsigned RAGreedy::selectOrSplitImpl(Liv
>>      NewVRegs.push_back(VirtReg.reg);
>>    } else {
>>      NamedRegionTimer T("Spiller", TimerGroupName, TimePassesIsEnabled);
>> -    LiveRangeEdit LRE(&VirtReg, NewVRegs, *MF, *LIS, VRM, this,
>> &DeadRemats);
>> +    LiveRangeEdit LRE(&VirtReg, NewVRegs, *MF, *LIS, VRM, this);
>>      spiller().spill(LRE);
>>      setStage(NewVRegs.begin(), NewVRegs.end(), RS_Done);
>>
>> @@ -2610,8 +2609,6 @@ bool RAGreedy::runOnMachineFunction(Mach
>>
>>    allocatePhysRegs();
>>    tryHintsRecoloring();
>> -  postOptimization();
>> -
>>    releaseMemory();
>>    return true;
>>  }
>>
>> Modified: llvm/trunk/lib/CodeGen/RegAllocPBQP.cpp
>> URL:
>> http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/RegAllocPBQP.cpp?rev=265317&r1=265316&r2=265317&view=diff
>>
>> ==============================================================================
>> --- llvm/trunk/lib/CodeGen/RegAllocPBQP.cpp (original)
>> +++ llvm/trunk/lib/CodeGen/RegAllocPBQP.cpp Mon Apr  4 12:45:03 2016
>> @@ -123,12 +123,6 @@ private:
>>
>>    RegSet VRegsToAlloc, EmptyIntervalVRegs;
>>
>> -  /// Inst which is a def of an original reg and whose defs are already
>> all
>> -  /// dead after remat is saved in DeadRemats. The deletion of such inst
>> is
>> -  /// postponed till all the allocations are done, so its remat expr is
>> -  /// always available for the remat of all the siblings of the original
>> reg.
>> -  SmallPtrSet<MachineInstr *, 32> DeadRemats;
>> -
>>    /// \brief Finds the initial set of vreg intervals to allocate.
>>    void findVRegIntervalsToAlloc(const MachineFunction &MF, LiveIntervals
>> &LIS);
>>
>> @@ -152,7 +146,6 @@ private:
>>    void finalizeAlloc(MachineFunction &MF, L
>
>


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