diff options
Diffstat (limited to 'lib/CodeGen/SplitKit.h')
| -rw-r--r-- | lib/CodeGen/SplitKit.h | 419 |
1 files changed, 242 insertions, 177 deletions
diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h index ddef7461dc3d6..5c34afd1c8195 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 // @@ -12,125 +12,132 @@ // //===----------------------------------------------------------------------===// -#include "llvm/ADT/SmallPtrSet.h" #include "llvm/ADT/DenseMap.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 NodeT> class DomTreeNodeBase; +typedef DomTreeNodeBase<MachineBasicBlock> 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; // Instructions using the the current register. typedef SmallPtrSet<const MachineInstr*, 16> InstrPtrSet; - InstrPtrSet usingInstrs_; + InstrPtrSet UsingInstrs; + + // Sorted slot indexes of using instructions. + SmallVector<SlotIndex, 8> UseSlots; - // The number of instructions using curli in each basic block. + // The number of instructions using CurLI in each basic block. typedef DenseMap<const MachineBasicBlock*, unsigned> BlockCountMap; - BlockCountMap usingBlocks_; + 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. + /// 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. + /// 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). + 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. + }; - // The number of basic block using curli in each loop. - typedef DenseMap<const MachineLoop*, unsigned> LoopCountMap; - LoopCountMap usingLoops_; + /// Basic blocks where var is live. This array is parallel to + /// SpillConstraints. + SmallVector<BlockInfo, 8> LiveBlocks; private: // Current live interval. - const LiveInterval *curli_; + const LiveInterval *CurLI; - // Sumarize statistics by counting instructions using curli_. + // 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); 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); - /// removeUse - Update statistics by noting that mi no longer uses curli. - void removeUse(const MachineInstr *mi); - - const LiveInterval *getCurLI() { return curli_; } - /// clear - clear all data structures so SplitAnalysis is ready to analyze a /// new interval. void clear(); - typedef SmallPtrSet<const MachineBasicBlock*, 16> BlockPtrSet; - typedef SmallPtrSet<const MachineLoop*, 16> 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(); - } - }; - - // Calculate the block sets surrounding the loop. - void getLoopBlocks(const MachineLoop *Loop, LoopBlocks &Blocks); - - /// 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. - }; - - /// analyzeLoopPeripheralUse - Return an enum describing how curli_ is used in - /// and around the Loop. - LoopPeripheralUse analyzeLoopPeripheralUse(const LoopBlocks&); + /// getParent - Return the last analyzed interval. + const LiveInterval &getParent() const { return *CurLI; } - /// 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); + /// hasUses - Return true if MBB has any uses of CurLI. + bool hasUses(const MachineBasicBlock *MBB) const { + return UsingBlocks.lookup(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); + typedef SmallPtrSet<const MachineBasicBlock*, 16> BlockPtrSet; - /// getBestSplitLoop - Return the loop where curli may best be split to a - /// separate register, or NULL. - const MachineLoop *getBestSplitLoop(); + // 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 + /// 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 + /// 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(); }; @@ -140,58 +147,102 @@ public: /// 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. +/// 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_; + LiveIntervals &LIS; + MachineDominatorTree &MDT; // The parent interval is never changed. - const LiveInterval &parentli_; + const LiveInterval &ParentLI; - // The child interval's values are fully contained inside parentli_ values. - LiveInterval &li_; + // The child interval's values are fully contained inside ParentLI values. + LiveInterval *LI; typedef DenseMap<const VNInfo*, VNInfo*> 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. + // 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_; - - // 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 Idx. - // Return the found VNInfo, or NULL. - VNInfo *extendTo(MachineBasicBlock *MBB, SlotIndex Idx); - - // 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); + ValueMap Values; + + typedef std::pair<VNInfo*, MachineDomTreeNode*> LiveOutPair; + typedef DenseMap<MachineBasicBlock*,LiveOutPair> 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, - const LiveInterval &parentli, - LiveInterval &li) - : lis_(lis), parentli_(parentli), li_(li) {} + MachineDominatorTree &mdt, + const LiveInterval &parentli) + : LIS(lis), MDT(mdt), 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. + /// 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. + /// 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 + /// 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_. - VNInfo *mapValue(const VNInfo *ParentVNI, SlotIndex Idx); + /// 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); + } + + /// 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; } + + // 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_. + /// 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); @@ -207,115 +258,129 @@ 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_; - - /// curli_ - The immutable interval we are currently splitting. - const LiveInterval *const curli_; - - /// 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_. - LiveInterval *dupli_; - - /// Currently open LiveInterval. - LiveInterval *openli_; - - /// createInterval - Create a new virtual register and LiveInterval with same - /// register class and spill slot as curli. - LiveInterval *createInterval(); - - /// getDupLI - Ensure dupli is created and return it. - LiveInterval *getDupLI(); - - /// valueMap_ - Map values in cupli to values in openli. These are direct 1-1 - /// mappings, and do not include values created by inserted copies. - DenseMap<const VNInfo*, VNInfo*> valueMap_; - - /// mapValue - Return the openIntv value that corresponds to the given curli - /// value. - VNInfo *mapValue(const VNInfo *curliVNI); - - /// A dupli value is live through openIntv. - bool liveThrough_; - - /// All the new intervals created for this split are added to intervals_. - SmallVectorImpl<LiveInterval*> &intervals_; - - /// The index into intervals_ of the first interval we added. There may be - /// others from before we got it. - unsigned firstInterval; - - /// Insert a COPY instruction curli -> li. Allocate a new value from li - /// defined by the COPY - VNInfo *insertCopy(LiveInterval &LI, - MachineBasicBlock &MBB, - MachineBasicBlock::iterator I); + 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; + + /// LIMappers - One LiveIntervalMap or each interval in Edit. + SmallVector<LiveIntervalMap, 4> LIMappers; + + /// 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); + + /// rewriteAssigned - Rewrite all uses of Edit.getReg() to assigned registers. + void rewriteAssigned(); + + /// 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<LiveInterval*> &Intvs, + const ConnectedVNInfoEqClasses &ConEq); 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<LiveInterval*> &newIntervals); + MachineDominatorTree&, LiveRangeEdit&); /// getAnalysis - Get the corresponding analysis. - SplitAnalysis &getAnalysis() { return sa_; } + SplitAnalysis &getAnalysis() { return SA; } /// Create a new virtual register and live interval. void 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); + /// 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 openli at the end of MBB. - /// PhiMBB is a successor inside openli where a PHI value is created. - /// Currently, all entries must share the same PhiMBB. - void enterIntvAtEnd(MachineBasicBlock &MBB, MachineBasicBlock &PhiMBB); + /// 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. + /// 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); + /// 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. - /// Currently, only one value can leave the interval. - void leaveIntvAtTop(MachineBasicBlock &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); /// closeIntv - Indicate that we are done editing the currently open /// LiveInterval, and ranges can be trimmed. void closeIntv(); - /// rewrite - after all the new live ranges have been created, rewrite - /// instructions using curli to use the new intervals. - void rewrite(); + /// 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(); - // ===--- High level methods ---=== + /// dump - print the current interval maping to dbgs(). + void dump() const; - /// splitAroundLoop - Split curli into a separate live interval inside - /// the loop. Return true if curli has been completely replaced, false if - /// curli is still intact, and needs to be spilled or split further. - bool splitAroundLoop(const MachineLoop*); + // ===--- High level methods ---=== - /// splitSingleBlocks - Split curli into a separate live interval inside each - /// basic block in Blocks. Return true if curli has been completely replaced, - /// false if curli is still intact, and needs to be spilled or split further. - bool splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks); + /// 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. Return - /// true if curli has been completely replaced, false if curli is still - /// intact, and needs to be spilled or split further. - bool splitInsideBlock(const MachineBasicBlock *); + /// splitInsideBlock - Split CurLI into multiple intervals inside MBB. + void splitInsideBlock(const MachineBasicBlock *); }; } |