-//===---------- SplitKit.cpp - Toolkit for splitting live ranges ----------===//
+//===-------- SplitKit.cpp - Toolkit for splitting live ranges --*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/DenseMap.h"
+#include "llvm/CodeGen/SlotIndexes.h"
namespace llvm {
class LiveInterval;
class LiveIntervals;
-class MachineBasicBlock;
+class LiveRangeEdit;
class MachineInstr;
-class MachineFunction;
-class MachineFunctionPass;
class MachineLoop;
class MachineLoopInfo;
+class MachineRegisterInfo;
+class TargetInstrInfo;
+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_;
-
- // Current live interval.
- const LiveInterval *curli_;
+ const TargetInstrInfo &tii_;
// Instructions using the the current register.
typedef SmallPtrSet<const MachineInstr*, 16> InstrPtrSet;
typedef DenseMap<const MachineBasicBlock*, unsigned> BlockCountMap;
BlockCountMap usingBlocks_;
- // Loops where the curent interval is used.
- typedef SmallPtrSet<const MachineLoop*, 16> LoopPtrSet;
- LoopPtrSet usingLoops_;
+ // The number of basic block using curli in each loop.
+ typedef DenseMap<const MachineLoop*, unsigned> LoopCountMap;
+ LoopCountMap usingLoops_;
+
+private:
+ // Current live interval.
+ const LiveInterval *curli_;
// Sumarize statistics by counting instructions using curli_.
- void analyseUses();
+ void analyzeUses();
+
+ /// 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,
- const MachineLoopInfo *mli);
+ SplitAnalysis(const MachineFunction &mf, const LiveIntervals &lis,
+ const MachineLoopInfo &mli);
/// analyze - set curli to the specified interval, and analyze how it may be
/// split.
/// new interval.
void clear();
+ typedef SmallPtrSet<const MachineBasicBlock*, 16> BlockPtrSet;
+ typedef SmallPtrSet<const MachineLoop*, 16> LoopPtrSet;
+
+ // Print a set of blocks with use counts.
+ void print(const BlockPtrSet&, raw_ostream&) const;
+
+ // 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();
+ }
+ };
+
+ // Print loop blocks with use counts.
+ void print(const LoopBlocks&, raw_ostream&) const;
+
+ // 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 {
/// analyzeLoopPeripheralUse - Return an enum describing how curli_ is used in
/// and around the Loop.
- LoopPeripheralUse analyzeLoopPeripheralUse(const MachineLoop*);
+ LoopPeripheralUse analyzeLoopPeripheralUse(const LoopBlocks&);
+
+ /// 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);
+
+ /// canSplitCriticalExits - Return true if it is possible to insert new exit
+ /// blocks before the blocks in CriticalExits.
+ bool canSplitCriticalExits(const LoopBlocks &Blocks,
+ BlockPtrSet &CriticalExits);
+
+ /// getCriticalPreds - Get the set of loop predecessors with critical edges to
+ /// blocks outside the loop that have curli live in. We don't have to break
+ /// these edges, but they do require special treatment.
+ void getCriticalPreds(const LoopBlocks &Blocks, BlockPtrSet &CriticalPreds);
/// getBestSplitLoop - Return the loop where curli may best be split to a
/// separate register, or NULL.
const MachineLoop *getBestSplitLoop();
+
+ /// 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 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_;
+ MachineDominatorTree &mdt_;
+
+ // The parent interval is never changed.
+ const LiveInterval &parentli_;
+
+ // 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.
+ // Note there is a difference between values mapping to NULL (complex), and
+ // values not present (unknown/unmapped).
+ ValueMap valueMap_;
+
+ 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_;
+
+public:
+ LiveIntervalMap(LiveIntervals &lis,
+ 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.
+ /// 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 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);
+
+ /// defByCopy- Insert a copy from parentli to li, assuming that ParentVNI is
+ /// live at the insert location. Add a minimal live range for the new value
+ /// and return it.
+ VNInfo *defByCopy(const VNInfo *ParentVNI,
+ MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator I);
+
};
-/// 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_;
+ const TargetInstrInfo &tii_;
+
+ /// edit_ - The current parent register and new intervals created.
+ LiveRangeEdit &edit_;
+
+ /// 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_;
+
+ /// Currently open LiveInterval.
+ LiveIntervalMap openli_;
+
+ /// intervalsLiveAt - Return true if any member of intervals_ is live at Idx.
+ bool intervalsLiveAt(SlotIndex Idx) const;
+
+ /// Values in curli whose live range has been truncated when entering an open
+ /// li.
+ SmallPtrSet<const VNInfo*, 8> truncatedValues;
+
+ /// addTruncSimpleRange - Add the given simple range to dupli_ after
+ /// truncating any overlap with intervals_.
+ void addTruncSimpleRange(SlotIndex Start, SlotIndex End, VNInfo *VNI);
+
+ /// criticalPreds_ - Set of basic blocks where both dupli and openli should be
+ /// live out because of a critical edge.
+ SplitAnalysis::BlockPtrSet criticalPreds_;
+
+ /// computeRemainder - Compute the dupli liveness as the complement of all the
+ /// new intervals.
+ void computeRemainder();
+
+ /// rewrite - Rewrite all uses of reg to use the new registers.
+ void rewrite(unsigned reg);
+
+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&);
+
+ /// getAnalysis - Get the corresponding analysis.
+ 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);
+
+ /// enterIntvAtEnd - Enter openli at the end of MBB.
+ void 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 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);
+
+ /// 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();
+
+ // ===--- High level methods ---===
+
+ /// splitAroundLoop - Split curli into a separate live interval inside
+ /// the loop.
+ void splitAroundLoop(const MachineLoop*);
+
+ /// 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 *);
+};
}
projects / oota-llvm.git / blobdiff