X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FCodeGen%2FSplitKit.h;h=cc41e2e321e839e0d850b366dbc4725aec348795;hb=b34d837397053da8e9bff90dd714e24f2a3b98b3;hp=e76cbc6ce3e4ec96ca9cb00d393ed93c53844533;hpb=fc3ef3c2e9e1a01f19aaf1e362d8d2f209c09a46;p=oota-llvm.git diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h index e76cbc6ce3e..cc41e2e321e 100644 --- a/lib/CodeGen/SplitKit.h +++ b/lib/CodeGen/SplitKit.h @@ -1,4 +1,4 @@ -//===---------- SplitKit.cpp - Toolkit for splitting live ranges ----------===// +//===-------- SplitKit.h - Toolkit for splitting live ranges ----*- C++ -*-===// // // The LLVM Compiler Infrastructure // @@ -12,211 +12,147 @@ // //===----------------------------------------------------------------------===// -#include "llvm/ADT/SmallPtrSet.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 LiveRangeEdit; class MachineInstr; -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 DomTreeNodeBase; +typedef DomTreeNodeBase MachineDomTreeNode; + /// SplitAnalysis - Analyze a LiveInterval, looking for live range splitting /// opportunities. class SplitAnalysis { public: - const MachineFunction &mf_; - const LiveIntervals &lis_; - const MachineLoopInfo &loops_; - const TargetInstrInfo &tii_; + const MachineFunction &MF; + const VirtRegMap &VRM; + const LiveIntervals &LIS; + const MachineLoopInfo &Loops; + const TargetInstrInfo &TII; + + // Sorted slot indexes of using instructions. + SmallVector 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. + /// 5. |---o---o---| Live-through with uses or defs. + /// 6. |-----------| Live-through without uses. Transparent. + /// + 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. + bool LiveThrough; ///< Live in whole block (Templ 5. or 6. above). + bool LiveIn; ///< Current reg is live in. + bool LiveOut; ///< Current reg is live out. + }; - // Instructions using the the current register. - typedef SmallPtrSet InstrPtrSet; - InstrPtrSet usingInstrs_; +private: + // Current live interval. + const LiveInterval *CurLI; - // The number of instructions using curli in each basic block. - typedef DenseMap BlockCountMap; - BlockCountMap usingBlocks_; + /// 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; - // The number of basic block using curli in each loop. - typedef DenseMap LoopCountMap; - LoopCountMap usingLoops_; + /// UseBlocks - Blocks where CurLI has uses. + SmallVector UseBlocks; -private: - // Current live interval. - const LiveInterval *curli_; + /// ThroughBlocks - Block numbers where CurLI is live through without uses. + BitVector ThroughBlocks; + + /// NumThroughBlocks - Number of live-through blocks. + unsigned NumThroughBlocks; - // Sumarize statistics by counting instructions using curli_. + SlotIndex computeLastSplitPoint(unsigned Num); + + // Sumarize statistics by counting instructions using CurLI. void analyzeUses(); - /// canAnalyzeBranch - Return true if MBB ends in a branch that can be - /// analyzed. - bool canAnalyzeBranch(const MachineBasicBlock *MBB); + /// calcLiveBlockInfo - Compute per-block information about CurLI. + 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 + /// analyze - set CurLI to the specified interval, and analyze how it may be /// split. void analyze(const LiveInterval *li); - const LiveInterval *getCurLI() { return curli_; } - /// clear - clear all data structures so SplitAnalysis is ready to analyze a /// new interval. void clear(); - typedef SmallPtrSet BlockPtrSet; - typedef SmallPtrSet LoopPtrSet; - - // Sets of basic blocks surrounding a machine loop. - struct LoopBlocks { - BlockPtrSet Loop; // Blocks in the loop. - BlockPtrSet Preds; // Loop predecessor blocks. - BlockPtrSet Exits; // Loop exit blocks. - - void clear() { - Loop.clear(); - Preds.clear(); - Exits.clear(); - } - }; + /// 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); + } - // Calculate the block sets surrounding the loop. - void getLoopBlocks(const MachineLoop *Loop, LoopBlocks &Blocks); + /// 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; - /// 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. - }; + /// getUseBlocks - Return an array of BlockInfo objects for the basic blocks + /// where CurLI has uses. + ArrayRef getUseBlocks() { return UseBlocks; } - /// analyzeLoopPeripheralUse - Return an enum describing how curli_ is used in - /// and around the Loop. - LoopPeripheralUse analyzeLoopPeripheralUse(const LoopBlocks&); + /// getNumThroughBlocks - Return the number of through blocks. + unsigned getNumThroughBlocks() const { return NumThroughBlocks; } - /// getCriticalExits - It may be necessary to partially break critical edges - /// leaving the loop if an exit block has phi uses of curli. Collect the exit - /// blocks that need special treatment into CriticalExits. - void getCriticalExits(const LoopBlocks &Blocks, BlockPtrSet &CriticalExits); + /// isThroughBlock - Return true if CurLI is live through MBB without uses. + bool isThroughBlock(unsigned MBB) const { return ThroughBlocks.test(MBB); } - /// canSplitCriticalExits - Return true if it is possible to insert new exit - /// blocks before the blocks in CriticalExits. - bool canSplitCriticalExits(const LoopBlocks &Blocks, - BlockPtrSet &CriticalExits); + /// getThroughBlocks - Return the set of through blocks. + const BitVector &getThroughBlocks() const { return ThroughBlocks; } - /// getBestSplitLoop - Return the loop where curli may best be split to a - /// separate register, or NULL. - const MachineLoop *getBestSplitLoop(); + typedef SmallPtrSet BlockPtrSet; /// getMultiUseBlocks - Add basic blocks to Blocks that may benefit from - /// having curli split to a new live interval. Return true if Blocks can be + /// 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 wou 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_; - - // The parent interval is never changed. - const LiveInterval &parentli_; - - // The child interval's values are fully contained inside parentli_ values. - LiveInterval *li_; - - typedef DenseMap ValueMap; - - // 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 valueMap_; - -public: - LiveIntervalMap(LiveIntervals &lis, - const LiveInterval &parentli) - : lis_(lis), parentli_(parentli), li_(0) {} - - /// reset - clear all data structures and start a new live interval. - void reset(LiveInterval *); - - /// getLI - return the current live interval. - LiveInterval *getLI() const { return li_; } - - /// 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(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 valueMap_.count(ParentVNI); - } - - /// isComplexMapped - Return true if ParentVNI has received new definitions - /// with defValue. - bool isComplexMapped(const VNInfo *ParentVNI) 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); - - /// 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); - - /// defByCopyFrom - Insert a copy from Reg to li, assuming that Reg carries - /// ParentVNI. Add a minimal live range for the new value and return it. - VNInfo *defByCopyFrom(unsigned Reg, - const VNInfo *ParentVNI, - MachineBasicBlock &MBB, - MachineBasicBlock::iterator I); - }; @@ -229,100 +165,224 @@ public: /// - 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 rewrite(). +/// - Rewrite instructions with finish(). /// class SplitEditor { - SplitAnalysis &sa_; - LiveIntervals &lis_; - VirtRegMap &vrm_; - MachineRegisterInfo &mri_; - const TargetInstrInfo &tii_; + 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 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, 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 LiveOutPair; + typedef IndexedMap 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) {} + }; - /// curli_ - The immutable interval we are currently splitting. - const LiveInterval *const curli_; + /// LiveInBlocks - List of live-in blocks used by findReachingDefs() and + /// updateSSA(). This list is usually empty, it exists here to avoid frequent + /// reallocations. + SmallVector LiveInBlocks; - /// dupli_ - Created as a copy of curli_, ranges are carved out as new - /// intervals get added through openIntv / closeIntv. This is used to avoid - /// editing curli_. - LiveIntervalMap dupli_; + /// 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); - /// Currently open LiveInterval. - LiveIntervalMap openli_; + /// 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); - /// createInterval - Create a new virtual register and LiveInterval with same - /// register class and spill slot as curli. - LiveInterval *createInterval(); + /// 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); - /// All the new intervals created for this split are added to intervals_. - SmallVectorImpl &intervals_; + /// 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(); - /// The index into intervals_ of the first interval we added. There may be - /// others from before we got it. - unsigned firstInterval; + /// transferValues - Transfer values to the new ranges. + /// Return true if any ranges were skipped. + bool transferValues(); - /// intervalsLiveAt - Return true if any member of intervals_ is live at Idx. - bool intervalsLiveAt(SlotIndex Idx) const; + /// extendPHIKillRanges - Extend the ranges of all values killed by original + /// parent PHIDefs. + void extendPHIKillRanges(); - /// Values in curli whose live range has been truncated when entering an open - /// li. - SmallPtrSet truncatedValues; + /// rewriteAssigned - Rewrite all uses of Edit.getReg() to assigned registers. + void rewriteAssigned(bool ExtendRanges); - /// addTruncSimpleRange - Add the given simple range to dupli_ after - /// truncating any overlap with intervals_. - void addTruncSimpleRange(SlotIndex Start, SlotIndex End, VNInfo *VNI); + /// 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&, - SmallVectorImpl &newIntervals); + MachineDominatorTree&); - /// getAnalysis - Get the corresponding analysis. - SplitAnalysis &getAnalysis() { return sa_; } + /// reset - Prepare for a new split. + void reset(LiveRangeEdit&); /// 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(); - /// enterIntvBefore - Enter openli before the instruction at Idx. If curli is - /// not live before Idx, a COPY is not inserted. - void enterIntvBefore(SlotIndex Idx); + /// currentIntv - Return the current interval index. + unsigned currentIntv() const { return OpenIdx; } - /// enterIntvAtEnd - Enter openli at the end of MBB. - void enterIntvAtEnd(MachineBasicBlock &MBB); + /// selectIntv - Select a previously opened interval index. + void selectIntv(unsigned Idx); - /// useIntv - indicate that all instructions in MBB should use openli. + /// 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); + + /// 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. + /// useIntv - indicate that all instructions in range should use OpenLI. void useIntv(SlotIndex Start, SlotIndex End); - /// leaveIntvAfter - Leave openli after the instruction at Idx. - void leaveIntvAfter(SlotIndex Idx); - - /// leaveIntvAtTop - Leave the interval at the top of MBB. - /// Currently, only one value can leave the interval. - void leaveIntvAtTop(MachineBasicBlock &MBB); + /// leaveIntvAfter - Leave the open interval after the instruction at Idx. + /// Return the end of the live range. + SlotIndex leaveIntvAfter(SlotIndex Idx); - /// closeIntv - Indicate that we are done editing the currently open - /// LiveInterval, and ranges can be trimmed. - void closeIntv(); + /// leaveIntvBefore - Leave the open interval before the instruction at Idx. + /// Return the end of the live range. + SlotIndex leaveIntvBefore(SlotIndex Idx); - /// rewrite - after all the new live ranges have been created, rewrite - /// instructions using curli to use the new intervals. - void rewrite(); + /// 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. + void finish(); + + /// dump - print the current interval maping to dbgs(). + void dump() const; // ===--- High level methods ---=== - /// splitAroundLoop - Split curli into a separate live interval inside - /// the loop. - void splitAroundLoop(const MachineLoop*); + /// 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); - /// splitSingleBlocks - Split curli into a separate live interval inside each + /// splitSingleBlocks - Split CurLI into a separate live interval inside each /// basic block in Blocks. void splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks); - - /// splitInsideBlock - Split curli into multiple intervals inside MBB. - void splitInsideBlock(const MachineBasicBlock *); }; }