-//===---------- SplitKit.cpp - Toolkit for splitting live ranges ----------===//
+//===-------- SplitKit.h - Toolkit for splitting live ranges ----*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
//
//===----------------------------------------------------------------------===//
-#include "llvm/ADT/SmallPtrSet.h"
+#ifndef LLVM_CODEGEN_SPLITKIT_H
+#define LLVM_CODEGEN_SPLITKIT_H
+
+#include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/BitVector.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/IndexedMap.h"
+#include "llvm/ADT/IntervalMap.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/CodeGen/SlotIndexes.h"
namespace llvm {
+class ConnectedVNInfoEqClasses;
class LiveInterval;
class LiveIntervals;
-class MachineBasicBlock;
+class LiveRangeEdit;
class MachineInstr;
-class MachineFunction;
-class MachineFunctionPass;
-class MachineLoop;
class MachineLoopInfo;
+class MachineRegisterInfo;
+class TargetInstrInfo;
+class TargetRegisterInfo;
+class VirtRegMap;
+class VNInfo;
+class raw_ostream;
+
+/// At some point we should just include MachineDominators.h:
+class MachineDominatorTree;
+template <class NodeT> class DomTreeNodeBase;
+typedef DomTreeNodeBase<MachineBasicBlock> MachineDomTreeNode;
+
+/// SplitAnalysis - Analyze a LiveInterval, looking for live range splitting
+/// opportunities.
class SplitAnalysis {
- const MachineFunction &mf_;
- const LiveIntervals &lis_;
- const MachineLoopInfo &loops_;
+public:
+ const MachineFunction &MF;
+ const VirtRegMap &VRM;
+ const LiveIntervals &LIS;
+ const MachineLoopInfo &Loops;
+ const TargetInstrInfo &TII;
+
+ // Sorted slot indexes of using instructions.
+ SmallVector<SlotIndex, 8> UseSlots;
+
+ /// 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_;
+ const LiveInterval *CurLI;
- // Instructions using the the current register.
- typedef SmallPtrSet<const MachineInstr*, 16> InstrPtrSet;
- InstrPtrSet usingInstrs_;
+ /// 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;
- // The number of instructions using curli in each basic block.
- typedef DenseMap<const MachineBasicBlock*, unsigned> BlockCountMap;
- BlockCountMap usingBlocks_;
+ /// UseBlocks - Blocks where CurLI has uses.
+ SmallVector<BlockInfo, 8> UseBlocks;
- // Loops where the curent interval is used.
- typedef SmallPtrSet<const MachineLoop*, 16> LoopPtrSet;
- LoopPtrSet usingLoops_;
+ /// NumGapBlocks - Number of duplicate entries in UseBlocks for blocks where
+ /// the live range has a gap.
+ unsigned NumGapBlocks;
- // Sumarize statistics by counting instructions using curli_.
+ /// 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 MachineFunction *mf, const LiveIntervals *lis,
- const MachineLoopInfo *mli);
+ SplitAnalysis(const VirtRegMap &vrm, const LiveIntervals &lis,
+ const MachineLoopInfo &mli);
- /// analyze - set curli to the specified interval, and analyze how it may be
+ /// 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();
- /// LoopPeripheralUse - how is a variable used in and around a loop?
- /// Peripheral blocks are the loop predecessors and exit blocks.
- enum LoopPeripheralUse {
- ContainedInLoop, // All uses are inside the loop.
- SinglePeripheral, // At most one instruction per peripheral block.
- MultiPeripheral, // Multiple instructions in some peripheral blocks.
- OutsideLoop // Uses outside loop periphery.
- };
+ /// getParent - Return the last analyzed interval.
+ const LiveInterval &getParent() const { return *CurLI; }
+
+ /// getLastSplitPoint - Return that 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);
+ }
+
+ /// 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;
- /// analyzeLoopPeripheralUse - Return an enum describing how curli_ is used in
- /// and around the Loop.
- LoopPeripheralUse analyzeLoopPeripheralUse(const MachineLoop*);
+ /// getUseBlocks - Return an array of BlockInfo objects for the basic blocks
+ /// where CurLI has uses.
+ ArrayRef<BlockInfo> getUseBlocks() const { return UseBlocks; }
- /// getBestSplitLoop - Return the loop where curli may best be split to a
- /// separate register, or NULL.
- const MachineLoop *getBestSplitLoop();
+ /// 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;
};
-/// splitAroundLoop - Try to split curli into a separate live interval inside
-/// the loop. Retun true on success.
-bool splitAroundLoop(SplitAnalysis&, const MachineLoop*);
+
+/// 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;
+
+ /// 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;
+
+ 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 DenseMap<std::pair<unsigned, unsigned>, VNInfo*> 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 - the value is mapped to multiple values in Edit.get(RegIdx).
+ /// Each value is represented by a minimal live range at its def.
+ /// 3. A non-null VNInfo - the value is mapped to a single new value.
+ /// The new value has no live ranges anywhere.
+ ValueMap Values;
+
+ typedef std::pair<VNInfo*, MachineDomTreeNode*> LiveOutPair;
+ typedef IndexedMap<LiveOutPair, MBB2NumberFunctor> LiveOutMap;
+
+ // LiveOutCache - Map each basic block where a new register is live out to the
+ // live-out value and its defining block.
+ // One of these conditions shall be true:
+ //
+ // 1. !LiveOutCache.count(MBB)
+ // 2. LiveOutCache[MBB].second.getNode() == MBB
+ // 3. forall P in preds(MBB): LiveOutCache[P] == LiveOutCache[MBB]
+ //
+ // This is only a cache, the values can be computed as:
+ //
+ // VNI = Edit.get(RegIdx)->getVNInfoAt(LIS.getMBBEndIdx(MBB))
+ // Node = mbt_[LIS.getMBBFromIndex(VNI->def)]
+ //
+ // The cache is also used as a visited set by extendRange(). It can be shared
+ // by all the new registers because at most one is live out of each block.
+ LiveOutMap LiveOutCache;
+
+ // LiveOutSeen - Indexed by MBB->getNumber(), a bit is set for each valid
+ // entry in LiveOutCache.
+ BitVector LiveOutSeen;
+
+ /// LiveInBlock - Info for updateSSA() about a block where a register is
+ /// live-in.
+ /// The updateSSA caller provides DomNode and Kill inside MBB, updateSSA()
+ /// adds the computed live-in value.
+ struct LiveInBlock {
+ // Dominator tree node for the block.
+ // Cleared by updateSSA when the final value has been determined.
+ MachineDomTreeNode *DomNode;
+
+ // Live-in value filled in by updateSSA once it is known.
+ VNInfo *Value;
+
+ // Position in block where the live-in range ends, or SlotIndex() if the
+ // range passes through the block.
+ SlotIndex Kill;
+
+ LiveInBlock(MachineDomTreeNode *node) : DomNode(node), Value(0) {}
+ };
+
+ /// LiveInBlocks - List of live-in blocks used by findReachingDefs() and
+ /// updateSSA(). This list is usually empty, it exists here to avoid frequent
+ /// reallocations.
+ SmallVector<LiveInBlock, 16> LiveInBlocks;
+
+ /// 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);
+
+ /// markComplexMapped - Mark ParentVNI as complex mapped in RegIdx regardless
+ /// of the number of defs.
+ void markComplexMapped(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);
+
+ /// extendRange - Extend the live range of Edit.get(RegIdx) so it reaches Idx.
+ /// Insert PHIDefs as needed to preserve SSA form.
+ void extendRange(unsigned RegIdx, SlotIndex Idx);
+
+ /// findReachingDefs - Starting from MBB, add blocks to LiveInBlocks until all
+ /// reaching defs for LI are found.
+ /// @param LI Live interval whose value is needed.
+ /// @param MBB Block where LI should be live-in.
+ /// @param Kill Kill point in MBB.
+ /// @return Unique value seen, or NULL.
+ VNInfo *findReachingDefs(LiveInterval *LI, MachineBasicBlock *MBB,
+ SlotIndex Kill);
+
+ /// updateSSA - Compute and insert PHIDefs such that all blocks in
+ // LiveInBlocks get a known live-in value. Add live ranges to the blocks.
+ void updateSSA();
+
+ /// 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&);
+
+ /// reset - Prepare for a new split.
+ void reset(LiveRangeEdit&);
+
+ /// 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
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