--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib/CodeGen/SplitKit.h	Thu Dec 12 13:56:28 2013 +0900
@@ -0,0 +1,471 @@
+//===-------- SplitKit.h - Toolkit for splitting live ranges ----*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the SplitAnalysis class as well as mutator functions for
+// live range splitting.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CODEGEN_SPLITKIT_H
+#define LLVM_CODEGEN_SPLITKIT_H
+
+#include "LiveRangeCalc.h"
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/IntervalMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+
+namespace llvm {
+
+class ConnectedVNInfoEqClasses;
+class LiveInterval;
+class LiveIntervals;
+class LiveRangeEdit;
+class MachineBlockFrequencyInfo;
+class MachineInstr;
+class MachineLoopInfo;
+class MachineRegisterInfo;
+class TargetInstrInfo;
+class TargetRegisterInfo;
+class VirtRegMap;
+class VNInfo;
+class raw_ostream;
+
+/// SplitAnalysis - Analyze a LiveInterval, looking for live range splitting
+/// opportunities.
+class SplitAnalysis {
+public:
+  const MachineFunction &MF;
+  const VirtRegMap &VRM;
+  const LiveIntervals &LIS;
+  const MachineLoopInfo &Loops;
+  const TargetInstrInfo &TII;
+
+  /// Additional information about basic blocks where the current variable is
+  /// live. Such a block will look like one of these templates:
+  ///
+  ///  1. |   o---x   | Internal to block. Variable is only live in this block.
+  ///  2. |---x       | Live-in, kill.
+  ///  3. |       o---| Def, live-out.
+  ///  4. |---x   o---| Live-in, kill, def, live-out. Counted by NumGapBlocks.
+  ///  5. |---o---o---| Live-through with uses or defs.
+  ///  6. |-----------| Live-through without uses. Counted by NumThroughBlocks.
+  ///
+  /// Two BlockInfo entries are created for template 4. One for the live-in
+  /// segment, and one for the live-out segment. These entries look as if the
+  /// block were split in the middle where the live range isn't live.
+  ///
+  /// Live-through blocks without any uses don't get BlockInfo entries. They
+  /// are simply listed in ThroughBlocks instead.
+  ///
+  struct BlockInfo {
+    MachineBasicBlock *MBB;
+    SlotIndex FirstInstr; ///< First instr accessing current reg.
+    SlotIndex LastInstr;  ///< Last instr accessing current reg.
+    SlotIndex FirstDef;   ///< First non-phi valno->def, or SlotIndex().
+    bool LiveIn;          ///< Current reg is live in.
+    bool LiveOut;         ///< Current reg is live out.
+
+    /// isOneInstr - Returns true when this BlockInfo describes a single
+    /// instruction.
+    bool isOneInstr() const {
+      return SlotIndex::isSameInstr(FirstInstr, LastInstr);
+    }
+  };
+
+private:
+  // Current live interval.
+  const LiveInterval *CurLI;
+
+  // Sorted slot indexes of using instructions.
+  SmallVector<SlotIndex, 8> UseSlots;
+
+  /// LastSplitPoint - Last legal split point in each basic block in the current
+  /// function. The first entry is the first terminator, the second entry is the
+  /// last valid split point for a variable that is live in to a landing pad
+  /// successor.
+  SmallVector<std::pair<SlotIndex, SlotIndex>, 8> LastSplitPoint;
+
+  /// UseBlocks - Blocks where CurLI has uses.
+  SmallVector<BlockInfo, 8> UseBlocks;
+
+  /// NumGapBlocks - Number of duplicate entries in UseBlocks for blocks where
+  /// the live range has a gap.
+  unsigned NumGapBlocks;
+
+  /// ThroughBlocks - Block numbers where CurLI is live through without uses.
+  BitVector ThroughBlocks;
+
+  /// NumThroughBlocks - Number of live-through blocks.
+  unsigned NumThroughBlocks;
+
+  /// DidRepairRange - analyze was forced to shrinkToUses().
+  bool DidRepairRange;
+
+  SlotIndex computeLastSplitPoint(unsigned Num);
+
+  // Sumarize statistics by counting instructions using CurLI.
+  void analyzeUses();
+
+  /// calcLiveBlockInfo - Compute per-block information about CurLI.
+  bool calcLiveBlockInfo();
+
+public:
+  SplitAnalysis(const VirtRegMap &vrm, const LiveIntervals &lis,
+                const MachineLoopInfo &mli);
+
+  /// analyze - set CurLI to the specified interval, and analyze how it may be
+  /// split.
+  void analyze(const LiveInterval *li);
+
+  /// didRepairRange() - Returns true if CurLI was invalid and has been repaired
+  /// by analyze(). This really shouldn't happen, but sometimes the coalescer
+  /// can create live ranges that end in mid-air.
+  bool didRepairRange() const { return DidRepairRange; }
+
+  /// clear - clear all data structures so SplitAnalysis is ready to analyze a
+  /// new interval.
+  void clear();
+
+  /// getParent - Return the last analyzed interval.
+  const LiveInterval &getParent() const { return *CurLI; }
+
+  /// getLastSplitPoint - Return the base index of the last valid split point
+  /// in the basic block numbered Num.
+  SlotIndex getLastSplitPoint(unsigned Num) {
+    // Inline the common simple case.
+    if (LastSplitPoint[Num].first.isValid() &&
+        !LastSplitPoint[Num].second.isValid())
+      return LastSplitPoint[Num].first;
+    return computeLastSplitPoint(Num);
+  }
+
+  /// getLastSplitPointIter - Returns the last split point as an iterator.
+  MachineBasicBlock::iterator getLastSplitPointIter(MachineBasicBlock*);
+
+  /// isOriginalEndpoint - Return true if the original live range was killed or
+  /// (re-)defined at Idx. Idx should be the 'def' slot for a normal kill/def,
+  /// and 'use' for an early-clobber def.
+  /// This can be used to recognize code inserted by earlier live range
+  /// splitting.
+  bool isOriginalEndpoint(SlotIndex Idx) const;
+
+  /// getUseSlots - Return an array of SlotIndexes of instructions using CurLI.
+  /// This include both use and def operands, at most one entry per instruction.
+  ArrayRef<SlotIndex> getUseSlots() const { return UseSlots; }
+
+  /// getUseBlocks - Return an array of BlockInfo objects for the basic blocks
+  /// where CurLI has uses.
+  ArrayRef<BlockInfo> getUseBlocks() const { return UseBlocks; }
+
+  /// getNumThroughBlocks - Return the number of through blocks.
+  unsigned getNumThroughBlocks() const { return NumThroughBlocks; }
+
+  /// isThroughBlock - Return true if CurLI is live through MBB without uses.
+  bool isThroughBlock(unsigned MBB) const { return ThroughBlocks.test(MBB); }
+
+  /// getThroughBlocks - Return the set of through blocks.
+  const BitVector &getThroughBlocks() const { return ThroughBlocks; }
+
+  /// getNumLiveBlocks - Return the number of blocks where CurLI is live.
+  unsigned getNumLiveBlocks() const {
+    return getUseBlocks().size() - NumGapBlocks + getNumThroughBlocks();
+  }
+
+  /// countLiveBlocks - Return the number of blocks where li is live. This is
+  /// guaranteed to return the same number as getNumLiveBlocks() after calling
+  /// analyze(li).
+  unsigned countLiveBlocks(const LiveInterval *li) const;
+
+  typedef SmallPtrSet<const MachineBasicBlock*, 16> BlockPtrSet;
+
+  /// shouldSplitSingleBlock - Returns true if it would help to create a local
+  /// live range for the instructions in BI. There is normally no benefit to
+  /// creating a live range for a single instruction, but it does enable
+  /// register class inflation if the instruction has a restricted register
+  /// class.
+  ///
+  /// @param BI           The block to be isolated.
+  /// @param SingleInstrs True when single instructions should be isolated.
+  bool shouldSplitSingleBlock(const BlockInfo &BI, bool SingleInstrs) const;
+};
+
+
+/// SplitEditor - Edit machine code and LiveIntervals for live range
+/// splitting.
+///
+/// - Create a SplitEditor from a SplitAnalysis.
+/// - Start a new live interval with openIntv.
+/// - Mark the places where the new interval is entered using enterIntv*
+/// - Mark the ranges where the new interval is used with useIntv* 
+/// - Mark the places where the interval is exited with exitIntv*.
+/// - Finish the current interval with closeIntv and repeat from 2.
+/// - Rewrite instructions with finish().
+///
+class SplitEditor {
+  SplitAnalysis &SA;
+  LiveIntervals &LIS;
+  VirtRegMap &VRM;
+  MachineRegisterInfo &MRI;
+  MachineDominatorTree &MDT;
+  const TargetInstrInfo &TII;
+  const TargetRegisterInfo &TRI;
+  const MachineBlockFrequencyInfo &MBFI;
+
+public:
+
+  /// ComplementSpillMode - Select how the complement live range should be
+  /// created.  SplitEditor automatically creates interval 0 to contain
+  /// anything that isn't added to another interval.  This complement interval
+  /// can get quite complicated, and it can sometimes be an advantage to allow
+  /// it to overlap the other intervals.  If it is going to spill anyway, no
+  /// registers are wasted by keeping a value in two places at the same time.
+  enum ComplementSpillMode {
+    /// SM_Partition(Default) - Try to create the complement interval so it
+    /// doesn't overlap any other intervals, and the original interval is
+    /// partitioned.  This may require a large number of back copies and extra
+    /// PHI-defs.  Only segments marked with overlapIntv will be overlapping.
+    SM_Partition,
+
+    /// SM_Size - Overlap intervals to minimize the number of inserted COPY
+    /// instructions.  Copies to the complement interval are hoisted to their
+    /// common dominator, so only one COPY is required per value in the
+    /// complement interval.  This also means that no extra PHI-defs need to be
+    /// inserted in the complement interval.
+    SM_Size,
+
+    /// SM_Speed - Overlap intervals to minimize the expected execution
+    /// frequency of the inserted copies.  This is very similar to SM_Size, but
+    /// the complement interval may get some extra PHI-defs.
+    SM_Speed
+  };
+
+private:
+
+  /// Edit - The current parent register and new intervals created.
+  LiveRangeEdit *Edit;
+
+  /// Index into Edit of the currently open interval.
+  /// The index 0 is used for the complement, so the first interval started by
+  /// openIntv will be 1.
+  unsigned OpenIdx;
+
+  /// The current spill mode, selected by reset().
+  ComplementSpillMode SpillMode;
+
+  typedef IntervalMap<SlotIndex, unsigned> RegAssignMap;
+
+  /// Allocator for the interval map. This will eventually be shared with
+  /// SlotIndexes and LiveIntervals.
+  RegAssignMap::Allocator Allocator;
+
+  /// RegAssign - Map of the assigned register indexes.
+  /// Edit.get(RegAssign.lookup(Idx)) is the register that should be live at
+  /// Idx.
+  RegAssignMap RegAssign;
+
+  typedef PointerIntPair<VNInfo*, 1> ValueForcePair;
+  typedef DenseMap<std::pair<unsigned, unsigned>, ValueForcePair> ValueMap;
+
+  /// Values - keep track of the mapping from parent values to values in the new
+  /// intervals. Given a pair (RegIdx, ParentVNI->id), Values contains:
+  ///
+  /// 1. No entry - the value is not mapped to Edit.get(RegIdx).
+  /// 2. (Null, false) - the value is mapped to multiple values in
+  ///    Edit.get(RegIdx).  Each value is represented by a minimal live range at
+  ///    its def.  The full live range can be inferred exactly from the range
+  ///    of RegIdx in RegAssign.
+  /// 3. (Null, true).  As above, but the ranges in RegAssign are too large, and
+  ///    the live range must be recomputed using LiveRangeCalc::extend().
+  /// 4. (VNI, false) The value is mapped to a single new value.
+  ///    The new value has no live ranges anywhere.
+  ValueMap Values;
+
+  /// LRCalc - Cache for computing live ranges and SSA update.  Each instance
+  /// can only handle non-overlapping live ranges, so use a separate
+  /// LiveRangeCalc instance for the complement interval when in spill mode.
+  LiveRangeCalc LRCalc[2];
+
+  /// getLRCalc - Return the LRCalc to use for RegIdx.  In spill mode, the
+  /// complement interval can overlap the other intervals, so it gets its own
+  /// LRCalc instance.  When not in spill mode, all intervals can share one.
+  LiveRangeCalc &getLRCalc(unsigned RegIdx) {
+    return LRCalc[SpillMode != SM_Partition && RegIdx != 0];
+  }
+
+  /// defValue - define a value in RegIdx from ParentVNI at Idx.
+  /// Idx does not have to be ParentVNI->def, but it must be contained within
+  /// ParentVNI's live range in ParentLI. The new value is added to the value
+  /// map.
+  /// Return the new LI value.
+  VNInfo *defValue(unsigned RegIdx, const VNInfo *ParentVNI, SlotIndex Idx);
+
+  /// forceRecompute - Force the live range of ParentVNI in RegIdx to be
+  /// recomputed by LiveRangeCalc::extend regardless of the number of defs.
+  /// This is used for values whose live range doesn't match RegAssign exactly.
+  /// They could have rematerialized, or back-copies may have been moved.
+  void forceRecompute(unsigned RegIdx, const VNInfo *ParentVNI);
+
+  /// defFromParent - Define Reg from ParentVNI at UseIdx using either
+  /// rematerialization or a COPY from parent. Return the new value.
+  VNInfo *defFromParent(unsigned RegIdx,
+                        VNInfo *ParentVNI,
+                        SlotIndex UseIdx,
+                        MachineBasicBlock &MBB,
+                        MachineBasicBlock::iterator I);
+
+  /// removeBackCopies - Remove the copy instructions that defines the values
+  /// in the vector in the complement interval.
+  void removeBackCopies(SmallVectorImpl<VNInfo*> &Copies);
+
+  /// getShallowDominator - Returns the least busy dominator of MBB that is
+  /// also dominated by DefMBB.  Busy is measured by loop depth.
+  MachineBasicBlock *findShallowDominator(MachineBasicBlock *MBB,
+                                          MachineBasicBlock *DefMBB);
+
+  /// hoistCopiesForSize - Hoist back-copies to the complement interval in a
+  /// way that minimizes code size. This implements the SM_Size spill mode.
+  void hoistCopiesForSize();
+
+  /// transferValues - Transfer values to the new ranges.
+  /// Return true if any ranges were skipped.
+  bool transferValues();
+
+  /// extendPHIKillRanges - Extend the ranges of all values killed by original
+  /// parent PHIDefs.
+  void extendPHIKillRanges();
+
+  /// rewriteAssigned - Rewrite all uses of Edit.getReg() to assigned registers.
+  void rewriteAssigned(bool ExtendRanges);
+
+  /// deleteRematVictims - Delete defs that are dead after rematerializing.
+  void deleteRematVictims();
+
+public:
+  /// Create a new SplitEditor for editing the LiveInterval analyzed by SA.
+  /// Newly created intervals will be appended to newIntervals.
+  SplitEditor(SplitAnalysis &SA, LiveIntervals&, VirtRegMap&,
+              MachineDominatorTree&, MachineBlockFrequencyInfo &);
+
+  /// reset - Prepare for a new split.
+  void reset(LiveRangeEdit&, ComplementSpillMode = SM_Partition);
+
+  /// Create a new virtual register and live interval.
+  /// Return the interval index, starting from 1. Interval index 0 is the
+  /// implicit complement interval.
+  unsigned openIntv();
+
+  /// currentIntv - Return the current interval index.
+  unsigned currentIntv() const { return OpenIdx; }
+
+  /// selectIntv - Select a previously opened interval index.
+  void selectIntv(unsigned Idx);
+
+  /// enterIntvBefore - Enter the open interval before the instruction at Idx.
+  /// If the parent interval is not live before Idx, a COPY is not inserted.
+  /// Return the beginning of the new live range.
+  SlotIndex enterIntvBefore(SlotIndex Idx);
+
+  /// enterIntvAfter - Enter the open interval after the instruction at Idx.
+  /// Return the beginning of the new live range.
+  SlotIndex enterIntvAfter(SlotIndex Idx);
+
+  /// enterIntvAtEnd - Enter the open interval at the end of MBB.
+  /// Use the open interval from he inserted copy to the MBB end.
+  /// Return the beginning of the new live range.
+  SlotIndex enterIntvAtEnd(MachineBasicBlock &MBB);
+
+  /// useIntv - indicate that all instructions in MBB should use OpenLI.
+  void useIntv(const MachineBasicBlock &MBB);
+
+  /// useIntv - indicate that all instructions in range should use OpenLI.
+  void useIntv(SlotIndex Start, SlotIndex End);
+
+  /// leaveIntvAfter - Leave the open interval after the instruction at Idx.
+  /// Return the end of the live range.
+  SlotIndex leaveIntvAfter(SlotIndex Idx);
+
+  /// leaveIntvBefore - Leave the open interval before the instruction at Idx.
+  /// Return the end of the live range.
+  SlotIndex leaveIntvBefore(SlotIndex Idx);
+
+  /// leaveIntvAtTop - Leave the interval at the top of MBB.
+  /// Add liveness from the MBB top to the copy.
+  /// Return the end of the live range.
+  SlotIndex leaveIntvAtTop(MachineBasicBlock &MBB);
+
+  /// overlapIntv - Indicate that all instructions in range should use the open
+  /// interval, but also let the complement interval be live.
+  ///
+  /// This doubles the register pressure, but is sometimes required to deal with
+  /// register uses after the last valid split point.
+  ///
+  /// The Start index should be a return value from a leaveIntv* call, and End
+  /// should be in the same basic block. The parent interval must have the same
+  /// value across the range.
+  ///
+  void overlapIntv(SlotIndex Start, SlotIndex End);
+
+  /// finish - after all the new live ranges have been created, compute the
+  /// remaining live range, and rewrite instructions to use the new registers.
+  /// @param LRMap When not null, this vector will map each live range in Edit
+  ///              back to the indices returned by openIntv.
+  ///              There may be extra indices created by dead code elimination.
+  void finish(SmallVectorImpl<unsigned> *LRMap = 0);
+
+  /// dump - print the current interval maping to dbgs().
+  void dump() const;
+
+  // ===--- High level methods ---===
+
+  /// splitSingleBlock - Split CurLI into a separate live interval around the
+  /// uses in a single block. This is intended to be used as part of a larger
+  /// split, and doesn't call finish().
+  void splitSingleBlock(const SplitAnalysis::BlockInfo &BI);
+
+  /// splitLiveThroughBlock - Split CurLI in the given block such that it
+  /// enters the block in IntvIn and leaves it in IntvOut. There may be uses in
+  /// the block, but they will be ignored when placing split points.
+  ///
+  /// @param MBBNum      Block number.
+  /// @param IntvIn      Interval index entering the block.
+  /// @param LeaveBefore When set, leave IntvIn before this point.
+  /// @param IntvOut     Interval index leaving the block.
+  /// @param EnterAfter  When set, enter IntvOut after this point.
+  void splitLiveThroughBlock(unsigned MBBNum,
+                             unsigned IntvIn, SlotIndex LeaveBefore,
+                             unsigned IntvOut, SlotIndex EnterAfter);
+
+  /// splitRegInBlock - Split CurLI in the given block such that it enters the
+  /// block in IntvIn and leaves it on the stack (or not at all). Split points
+  /// are placed in a way that avoids putting uses in the stack interval. This
+  /// may require creating a local interval when there is interference.
+  ///
+  /// @param BI          Block descriptor.
+  /// @param IntvIn      Interval index entering the block. Not 0.
+  /// @param LeaveBefore When set, leave IntvIn before this point.
+  void splitRegInBlock(const SplitAnalysis::BlockInfo &BI,
+                       unsigned IntvIn, SlotIndex LeaveBefore);
+
+  /// splitRegOutBlock - Split CurLI in the given block such that it enters the
+  /// block on the stack (or isn't live-in at all) and leaves it in IntvOut.
+  /// Split points are placed to avoid interference and such that the uses are
+  /// not in the stack interval. This may require creating a local interval
+  /// when there is interference.
+  ///
+  /// @param BI          Block descriptor.
+  /// @param IntvOut     Interval index leaving the block.
+  /// @param EnterAfter  When set, enter IntvOut after this point.
+  void splitRegOutBlock(const SplitAnalysis::BlockInfo &BI,
+                        unsigned IntvOut, SlotIndex EnterAfter);
+};
+
+}
+
+#endif