X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FSplitKit.h;h=4005a3d5cbbfbd1b4c76d2752e60861e9da127c0;hb=770b97b995aace9177a80510b7fd3cdab21dde0e;hp=6f771b65525a6df53b611ccf80ee0edf99ffa77d;hpb=034a80d065358b412cdd270e08fb6f1986e65e50;p=oota-llvm.git diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h index 6f771b65525..4005a3d5cbb 100644 --- a/lib/CodeGen/SplitKit.h +++ b/lib/CodeGen/SplitKit.h @@ -12,10 +12,14 @@ // //===----------------------------------------------------------------------===// +#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" -#include "llvm/CodeGen/SlotIndexes.h" namespace llvm { @@ -32,86 +36,98 @@ class VirtRegMap; class VNInfo; class raw_ostream; -/// At some point we should just include MachineDominators.h: -class MachineDominatorTree; -template class DomTreeNodeBase; -typedef DomTreeNodeBase MachineDomTreeNode; - - /// 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; - // Instructions using the the current register. - typedef SmallPtrSet InstrPtrSet; - InstrPtrSet UsingInstrs; - - // Sorted slot indexes of using instructions. - SmallVector UseSlots; - - // The number of instructions using CurLI in each basic block. - typedef DenseMap BlockCountMap; - BlockCountMap UsingBlocks; - /// 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. + /// 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. Transparent. + /// 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 FirstUse; ///< First instr using current reg. - SlotIndex LastUse; ///< Last instr using current reg. - SlotIndex Kill; ///< Interval end point inside block. - SlotIndex Def; ///< Interval start point inside block. - /// Last possible point for splitting live ranges. - SlotIndex LastSplitPoint; - bool Uses; ///< Current reg has uses or defs in block. - bool LiveThrough; ///< Live in whole block (Templ 5. or 6. above). + 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. - // Per-interference pattern scratch data. - bool OverlapEntry; ///< Interference overlaps entering interval. - bool OverlapExit; ///< Interference overlaps exiting interval. + /// isOneInstr - Returns true when this BlockInfo describes a single + /// instruction. + bool isOneInstr() const { + return SlotIndex::isSameInstr(FirstInstr, LastInstr); + } }; - /// Basic blocks where var is live. This array is parallel to - /// SpillConstraints. - SmallVector LiveBlocks; - private: // Current live interval. const LiveInterval *CurLI; + // Sorted slot indexes of using instructions. + SmallVector 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, 8> LastSplitPoint; + + /// UseBlocks - Blocks where CurLI has uses. + SmallVector 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. - void calcLiveBlockInfo(); - - /// canAnalyzeBranch - Return true if MBB ends in a branch that can be - /// analyzed. - bool canAnalyzeBranch(const MachineBasicBlock *MBB); + bool calcLiveBlockInfo(); public: - SplitAnalysis(const MachineFunction &mf, const LiveIntervals &lis, + 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(); @@ -119,132 +135,64 @@ public: /// getParent - Return the last analyzed interval. const LiveInterval &getParent() const { return *CurLI; } - /// hasUses - Return true if MBB has any uses of CurLI. - bool hasUses(const MachineBasicBlock *MBB) const { - return UsingBlocks.lookup(MBB); + /// 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); } - typedef SmallPtrSet BlockPtrSet; - - // Print a set of blocks with use counts. - void print(const BlockPtrSet&, raw_ostream&) const; - - /// getMultiUseBlocks - Add basic blocks to Blocks that may benefit from - /// having CurLI split to a new live interval. Return true if Blocks can be - /// passed to SplitEditor::splitSingleBlocks. - bool getMultiUseBlocks(BlockPtrSet &Blocks); - - /// getBlockForInsideSplit - If CurLI is contained inside a single basic - /// block, and it would pay to subdivide the interval inside that block, - /// return it. Otherwise return NULL. The returned block can be passed to - /// SplitEditor::splitInsideBlock. - const MachineBasicBlock *getBlockForInsideSplit(); -}; - - -/// LiveIntervalMap - Map values from a large LiveInterval into a small -/// interval that is a subset. Insert phi-def values as needed. This class is -/// used by SplitEditor to create new smaller LiveIntervals. -/// -/// ParentLI is the larger interval, LI is the subset interval. Every value -/// in LI corresponds to exactly one value in ParentLI, and the live range -/// of the value is contained within the live range of the ParentLI value. -/// Values in ParentLI may map to any number of OpenLI values, including 0. -class LiveIntervalMap { - LiveIntervals &LIS; - MachineDominatorTree &MDT; + /// getLastSplitPointIter - Returns the last split point as an iterator. + MachineBasicBlock::iterator getLastSplitPointIter(MachineBasicBlock*); - // The parent interval is never changed. - const LiveInterval &ParentLI; + /// 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; - // The child interval's values are fully contained inside ParentLI values. - LiveInterval *LI; + /// getUseSlots - Return an array of SlotIndexes of instructions using CurLI. + /// This include both use and def operands, at most one entry per instruction. + ArrayRef getUseSlots() const { return UseSlots; } - typedef DenseMap ValueMap; + /// getUseBlocks - Return an array of BlockInfo objects for the basic blocks + /// where CurLI has uses. + ArrayRef getUseBlocks() const { return UseBlocks; } - // Map ParentLI values to simple values in LI that are defined at the same - // SlotIndex, or NULL for ParentLI values that have complex LI defs. - // Note there is a difference between values mapping to NULL (complex), and - // values not present (unknown/unmapped). - ValueMap Values; - - typedef std::pair LiveOutPair; - typedef DenseMap LiveOutMap; - - // LiveOutCache - Map each basic block where LI 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 = LI->getVNInfoAt(LIS.getMBBEndIdx(MBB)) - // Node = mbt_[LIS.getMBBFromIndex(VNI->def)] - // - // The cache is also used as a visiteed set by mapValue(). - LiveOutMap LiveOutCache; - - // Dump the live-out cache to dbgs(). - void dumpCache(); - -public: - LiveIntervalMap(LiveIntervals &lis, - MachineDominatorTree &mdt, - const LiveInterval &parentli) - : LIS(lis), MDT(mdt), ParentLI(parentli), LI(0) {} + /// getNumThroughBlocks - Return the number of through blocks. + unsigned getNumThroughBlocks() const { return NumThroughBlocks; } - /// reset - clear all data structures and start a new live interval. - void reset(LiveInterval *); + /// isThroughBlock - Return true if CurLI is live through MBB without uses. + bool isThroughBlock(unsigned MBB) const { return ThroughBlocks.test(MBB); } - /// getLI - return the current live interval. - LiveInterval *getLI() const { return LI; } + /// getThroughBlocks - Return the set of through blocks. + const BitVector &getThroughBlocks() const { return ThroughBlocks; } - /// defValue - define a value in LI from the ParentLI value VNI and Idx. - /// Idx does not have to be ParentVNI->def, but it must be contained within - /// ParentVNI's live range in ParentLI. - /// Return the new LI value. - VNInfo *defValue(const VNInfo *ParentVNI, SlotIndex Idx); - - /// mapValue - map ParentVNI to the corresponding LI value at Idx. It is - /// assumed that ParentVNI is live at Idx. - /// If ParentVNI has not been defined by defValue, it is assumed that - /// ParentVNI->def dominates Idx. - /// If ParentVNI has been defined by defValue one or more times, a value that - /// dominates Idx will be returned. This may require creating extra phi-def - /// values and adding live ranges to LI. - /// If simple is not NULL, *simple will indicate if ParentVNI is a simply - /// mapped value. - VNInfo *mapValue(const VNInfo *ParentVNI, SlotIndex Idx, bool *simple = 0); - - // extendTo - Find the last LI value defined in MBB at or before Idx. The - // parentli is assumed to be live at Idx. Extend the live range to include - // Idx. Return the found VNInfo, or NULL. - VNInfo *extendTo(const MachineBasicBlock *MBB, SlotIndex Idx); - - /// isMapped - Return true is ParentVNI is a known mapped value. It may be a - /// simple 1-1 mapping or a complex mapping to later defs. - bool isMapped(const VNInfo *ParentVNI) const { - return Values.count(ParentVNI); + /// getNumLiveBlocks - Return the number of blocks where CurLI is live. + unsigned getNumLiveBlocks() const { + return getUseBlocks().size() - NumGapBlocks + getNumThroughBlocks(); } - /// isComplexMapped - Return true if ParentVNI has received new definitions - /// with defValue. - bool isComplexMapped(const VNInfo *ParentVNI) const; - - /// markComplexMapped - Mark ParentVNI as complex mapped regardless of the - /// number of definitions. - void markComplexMapped(const VNInfo *ParentVNI) { Values[ParentVNI] = 0; } + /// 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; - // addSimpleRange - Add a simple range from ParentLI to LI. - // ParentVNI must be live in the [Start;End) interval. - void addSimpleRange(SlotIndex Start, SlotIndex End, const VNInfo *ParentVNI); + typedef SmallPtrSet BlockPtrSet; - /// addRange - Add live ranges to LI where [Start;End) intersects ParentLI. - /// All needed values whose def is not inside [Start;End) must be defined - /// beforehand so mapValue will work. - void addRange(SlotIndex Start, SlotIndex End); + /// 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; }; @@ -260,7 +208,7 @@ public: /// - Rewrite instructions with finish(). /// class SplitEditor { - SplitAnalysis &sa_; + SplitAnalysis &SA; LiveIntervals &LIS; VirtRegMap &VRM; MachineRegisterInfo &MRI; @@ -268,14 +216,47 @@ class SplitEditor { const TargetInstrInfo &TII; const TargetRegisterInfo &TRI; +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; + 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 RegAssignMap; /// Allocator for the interval map. This will eventually be shared with @@ -287,8 +268,47 @@ class SplitEditor { /// Idx. RegAssignMap RegAssign; - /// LIMappers - One LiveIntervalMap or each interval in Edit. - SmallVector LIMappers; + typedef PointerIntPair ValueForcePair; + typedef DenseMap, 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. @@ -298,33 +318,62 @@ class SplitEditor { MachineBasicBlock &MBB, MachineBasicBlock::iterator I); + /// removeBackCopies - Remove the copy instructions that defines the values + /// in the vector in the complement interval. + void removeBackCopies(SmallVectorImpl &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(); + void rewriteAssigned(bool ExtendRanges); - /// rewriteComponents - Rewrite all uses of Intv[0] according to the eq - /// classes in ConEQ. - /// This must be done when Intvs[0] is styill live at all uses, before calling - /// ConEq.Distribute(). - void rewriteComponents(const SmallVectorImpl &Intvs, - const ConnectedVNInfoEqClasses &ConEq); + /// 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&, LiveRangeEdit&); + MachineDominatorTree&); - /// getAnalysis - Get the corresponding analysis. - SplitAnalysis &getAnalysis() { return sa_; } + /// reset - Prepare for a new split. + void reset(LiveRangeEdit&, ComplementSpillMode = SM_Partition); /// Create a new virtual register and live interval. - void openIntv(); + /// 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. @@ -361,25 +410,60 @@ public: /// void overlapIntv(SlotIndex Start, SlotIndex End); - /// closeIntv - Indicate that we are done editing the currently open - /// LiveInterval, and ranges can be trimmed. - void closeIntv(); - /// finish - after all the new live ranges have been created, compute the /// remaining live range, and rewrite instructions to use the new registers. - void finish(); + /// @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 *LRMap = 0); /// dump - print the current interval maping to dbgs(). void dump() const; // ===--- High level methods ---=== - /// splitSingleBlocks - Split CurLI into a separate live interval inside each - /// basic block in Blocks. - void splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks); + /// 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); - /// splitInsideBlock - Split CurLI into multiple intervals inside MBB. - void splitInsideBlock(const MachineBasicBlock *); + /// 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