-//===---------- 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/ADT/IntEqClasses.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/CodeGen/SlotIndexes.h"
+#include <string>
+
namespace llvm {
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;
+
+
+/// EdgeBundles - Group CFG edges into equivalence classes where registers must
+/// be allocated identically. This annotates the CFG to form a bipartite graph
+/// where each block is connected to an ingoing and an outgoing bundle.
+/// Edge bundles are simply numbered, there is no object representation.
+class EdgeBundles {
+ const MachineFunction *MF;
+
+ /// EC - Each edge bundle is an equivalence class. The keys are:
+ /// 2*BB->getNumber() -> Ingoing bundle.
+ /// 2*BB->getNumber()+1 -> Outgoing bundle.
+ IntEqClasses EC;
+
+public:
+ /// compute - Compute the edge bundles for MF. Bundles depend only on the CFG.
+ void compute(const MachineFunction *MF);
+
+ /// getBundle - Return the ingoing (Out = false) or outgoing (Out = true)
+ /// bundle number for basic block #N
+ unsigned getBundle(unsigned N, bool Out) const { return EC[2 * N + Out]; }
+
+ /// getMachineFunction - Return the last machine function computed.
+ const MachineFunction *getMachineFunction() const { return MF; }
+
+ /// view - Visualize the annotated bipartite CFG with Graphviz.
+ void view() const;
+};
+
+/// Specialize WriteGraph, the standard implementation won't work.
+raw_ostream &WriteGraph(raw_ostream &O, const EdgeBundles &G,
+ bool ShortNames = false,
+ const std::string &Title = "");
+
/// SplitAnalysis - Analyze a LiveInterval, looking for live range splitting
/// opportunities.
/// 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;
+ // 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.
}
};
+ // 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);
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);
+
+ /// getSplitLoops - Get the set of loops that have curli uses and would be
+ /// profitable to split.
+ void getSplitLoops(LoopPtrSet&);
+
/// getBestSplitLoop - Return the loop where curli may best be split to a
/// separate register, or NULL.
const MachineLoop *getBestSplitLoop();
+ /// isBypassLoop - Return true if curli is live through Loop and has no uses
+ /// inside the loop. Bypass loops are candidates for splitting because it can
+ /// prevent interference inside the loop.
+ bool isBypassLoop(const MachineLoop *Loop);
+
+ /// getBypassLoops - Get all the maximal bypass loops. These are the bypass
+ /// loops whose parent is not a bypass loop.
+ void getBypassLoops(LoopPtrSet&);
+
/// 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.
/// 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_;
+ LiveInterval *li_;
typedef DenseMap<const VNInfo*, VNInfo*> ValueMap;
// 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);
+ 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,
- 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.
/// Idx does not have to be ParentVNI->def, but it must be contained within
/// 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);
+ /// 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
/// - 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_;
VirtRegMap &vrm_;
MachineRegisterInfo &mri_;
const TargetInstrInfo &tii_;
+ const TargetRegisterInfo &tri_;
- /// curli_ - The immutable interval we are currently splitting.
- const LiveInterval *const curli_;
+ /// 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_.
- LiveInterval *dupli_;
+ LiveIntervalMap dupli_;
/// Currently open LiveInterval.
- LiveInterval *openli_;
+ LiveIntervalMap openli_;
- /// createInterval - Create a new virtual register and LiveInterval with same
- /// register class and spill slot as curli.
- LiveInterval *createInterval();
+ /// defFromParent - Define Reg from ParentVNI at UseIdx using either
+ /// rematerialization or a COPY from parent. Return the new value.
+ VNInfo *defFromParent(LiveIntervalMap &Reg,
+ VNInfo *ParentVNI,
+ SlotIndex UseIdx,
+ MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator I);
- /// getDupLI - Ensure dupli is created and return it.
- LiveInterval *getDupLI();
+ /// intervalsLiveAt - Return true if any member of intervals_ is live at Idx.
+ bool intervalsLiveAt(SlotIndex Idx) const;
- /// 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_;
+ /// Values in curli whose live range has been truncated when entering an open
+ /// li.
+ SmallPtrSet<const VNInfo*, 8> truncatedValues;
- /// mapValue - Return the openIntv value that corresponds to the given curli
- /// value.
- VNInfo *mapValue(const VNInfo *curliVNI);
+ /// addTruncSimpleRange - Add the given simple range to dupli_ after
+ /// truncating any overlap with intervals_.
+ void addTruncSimpleRange(SlotIndex Start, SlotIndex End, VNInfo *VNI);
- /// A dupli value is live through openIntv.
- bool liveThrough_;
+ /// criticalPreds_ - Set of basic blocks where both dupli and openli should be
+ /// live out because of a critical edge.
+ SplitAnalysis::BlockPtrSet criticalPreds_;
- /// All the new intervals created for this split are added to intervals_.
- SmallVectorImpl<LiveInterval*> &intervals_;
+ /// computeRemainder - Compute the dupli liveness as the complement of all the
+ /// new intervals.
+ void computeRemainder();
- /// 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);
+ /// 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&,
- SmallVectorImpl<LiveInterval*> &newIntervals);
+ MachineDominatorTree&, LiveRangeEdit&);
/// getAnalysis - Get the corresponding analysis.
SplitAnalysis &getAnalysis() { return sa_; }
void 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);
+ void enterIntvAtEnd(MachineBasicBlock &MBB);
/// useIntv - indicate that all instructions in MBB should use openli.
void useIntv(const MachineBasicBlock &MBB);
/// 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 ---===
/// 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*);
+ /// the loop.
+ void splitAroundLoop(const MachineLoop*);
/// 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);
-
- /// 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 *);
+ /// basic block in Blocks.
+ void splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks);
+
+ /// splitInsideBlock - Split curli into multiple intervals inside MBB.
+ void splitInsideBlock(const MachineBasicBlock *);
};
}
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