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No functional change. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124257 91177308-0d34-0410-b5e6-96231b3b80d8
392 lines
14 KiB
C++
392 lines
14 KiB
C++
//===-------- SplitKit.h - Toolkit for splitting live ranges ----*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the SplitAnalysis class as well as mutator functions for
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// live range splitting.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/SmallPtrSet.h"
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#include "llvm/CodeGen/SlotIndexes.h"
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namespace llvm {
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class LiveInterval;
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class LiveIntervals;
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class LiveRangeEdit;
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class MachineInstr;
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class MachineLoop;
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class MachineLoopInfo;
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class MachineRegisterInfo;
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class TargetInstrInfo;
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class TargetRegisterInfo;
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class VirtRegMap;
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class VNInfo;
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class raw_ostream;
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/// At some point we should just include MachineDominators.h:
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class MachineDominatorTree;
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template <class NodeT> class DomTreeNodeBase;
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typedef DomTreeNodeBase<MachineBasicBlock> MachineDomTreeNode;
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/// SplitAnalysis - Analyze a LiveInterval, looking for live range splitting
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/// opportunities.
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class SplitAnalysis {
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public:
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const MachineFunction &MF;
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const LiveIntervals &LIS;
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const MachineLoopInfo &Loops;
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const TargetInstrInfo &TII;
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// Instructions using the the current register.
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typedef SmallPtrSet<const MachineInstr*, 16> InstrPtrSet;
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InstrPtrSet UsingInstrs;
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// Sorted slot indexes of using instructions.
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SmallVector<SlotIndex, 8> UseSlots;
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// The number of instructions using CurLI in each basic block.
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typedef DenseMap<const MachineBasicBlock*, unsigned> BlockCountMap;
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BlockCountMap UsingBlocks;
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// The number of basic block using CurLI in each loop.
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typedef DenseMap<const MachineLoop*, unsigned> LoopCountMap;
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LoopCountMap UsingLoops;
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private:
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// Current live interval.
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const LiveInterval *CurLI;
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// Sumarize statistics by counting instructions using CurLI.
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void analyzeUses();
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/// canAnalyzeBranch - Return true if MBB ends in a branch that can be
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/// analyzed.
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bool canAnalyzeBranch(const MachineBasicBlock *MBB);
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public:
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SplitAnalysis(const MachineFunction &mf, const LiveIntervals &lis,
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const MachineLoopInfo &mli);
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/// analyze - set CurLI to the specified interval, and analyze how it may be
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/// split.
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void analyze(const LiveInterval *li);
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/// clear - clear all data structures so SplitAnalysis is ready to analyze a
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/// new interval.
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void clear();
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/// hasUses - Return true if MBB has any uses of CurLI.
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bool hasUses(const MachineBasicBlock *MBB) const {
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return UsingBlocks.lookup(MBB);
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}
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typedef SmallPtrSet<const MachineBasicBlock*, 16> BlockPtrSet;
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typedef SmallPtrSet<const MachineLoop*, 16> LoopPtrSet;
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// Print a set of blocks with use counts.
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void print(const BlockPtrSet&, raw_ostream&) const;
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// Sets of basic blocks surrounding a machine loop.
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struct LoopBlocks {
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BlockPtrSet Loop; // Blocks in the loop.
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BlockPtrSet Preds; // Loop predecessor blocks.
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BlockPtrSet Exits; // Loop exit blocks.
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void clear() {
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Loop.clear();
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Preds.clear();
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Exits.clear();
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}
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};
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// Print loop blocks with use counts.
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void print(const LoopBlocks&, raw_ostream&) const;
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// Calculate the block sets surrounding the loop.
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void getLoopBlocks(const MachineLoop *Loop, LoopBlocks &Blocks);
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/// LoopPeripheralUse - how is a variable used in and around a loop?
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/// Peripheral blocks are the loop predecessors and exit blocks.
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enum LoopPeripheralUse {
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ContainedInLoop, // All uses are inside the loop.
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SinglePeripheral, // At most one instruction per peripheral block.
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MultiPeripheral, // Multiple instructions in some peripheral blocks.
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OutsideLoop // Uses outside loop periphery.
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};
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/// analyzeLoopPeripheralUse - Return an enum describing how CurLI is used in
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/// and around the Loop.
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LoopPeripheralUse analyzeLoopPeripheralUse(const LoopBlocks&);
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/// getCriticalExits - It may be necessary to partially break critical edges
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/// leaving the loop if an exit block has phi uses of CurLI. Collect the exit
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/// blocks that need special treatment into CriticalExits.
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void getCriticalExits(const LoopBlocks &Blocks, BlockPtrSet &CriticalExits);
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/// canSplitCriticalExits - Return true if it is possible to insert new exit
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/// blocks before the blocks in CriticalExits.
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bool canSplitCriticalExits(const LoopBlocks &Blocks,
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BlockPtrSet &CriticalExits);
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/// getCriticalPreds - Get the set of loop predecessors with critical edges to
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/// blocks outside the loop that have CurLI live in. We don't have to break
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/// these edges, but they do require special treatment.
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void getCriticalPreds(const LoopBlocks &Blocks, BlockPtrSet &CriticalPreds);
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/// getSplitLoops - Get the set of loops that have CurLI uses and would be
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/// profitable to split.
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void getSplitLoops(LoopPtrSet&);
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/// getBestSplitLoop - Return the loop where CurLI may best be split to a
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/// separate register, or NULL.
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const MachineLoop *getBestSplitLoop();
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/// isBypassLoop - Return true if CurLI is live through Loop and has no uses
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/// inside the loop. Bypass loops are candidates for splitting because it can
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/// prevent interference inside the loop.
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bool isBypassLoop(const MachineLoop *Loop);
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/// getBypassLoops - Get all the maximal bypass loops. These are the bypass
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/// loops whose parent is not a bypass loop.
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void getBypassLoops(LoopPtrSet&);
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/// getMultiUseBlocks - Add basic blocks to Blocks that may benefit from
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/// having CurLI split to a new live interval. Return true if Blocks can be
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/// passed to SplitEditor::splitSingleBlocks.
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bool getMultiUseBlocks(BlockPtrSet &Blocks);
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/// getBlockForInsideSplit - If CurLI is contained inside a single basic
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/// block, and it would pay to subdivide the interval inside that block,
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/// return it. Otherwise return NULL. The returned block can be passed to
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/// SplitEditor::splitInsideBlock.
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const MachineBasicBlock *getBlockForInsideSplit();
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};
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/// LiveIntervalMap - Map values from a large LiveInterval into a small
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/// interval that is a subset. Insert phi-def values as needed. This class is
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/// used by SplitEditor to create new smaller LiveIntervals.
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///
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/// ParentLI is the larger interval, LI is the subset interval. Every value
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/// in LI corresponds to exactly one value in ParentLI, and the live range
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/// of the value is contained within the live range of the ParentLI value.
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/// Values in ParentLI may map to any number of OpenLI values, including 0.
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class LiveIntervalMap {
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LiveIntervals &LIS;
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MachineDominatorTree &MDT;
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// The parent interval is never changed.
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const LiveInterval &ParentLI;
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// The child interval's values are fully contained inside ParentLI values.
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LiveInterval *LI;
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typedef DenseMap<const VNInfo*, VNInfo*> ValueMap;
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// Map ParentLI values to simple values in LI that are defined at the same
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// SlotIndex, or NULL for ParentLI values that have complex LI defs.
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// Note there is a difference between values mapping to NULL (complex), and
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// values not present (unknown/unmapped).
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ValueMap Values;
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typedef std::pair<VNInfo*, MachineDomTreeNode*> LiveOutPair;
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typedef DenseMap<MachineBasicBlock*,LiveOutPair> LiveOutMap;
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// LiveOutCache - Map each basic block where LI is live out to the live-out
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// value and its defining block. One of these conditions shall be true:
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//
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// 1. !LiveOutCache.count(MBB)
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// 2. LiveOutCache[MBB].second.getNode() == MBB
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// 3. forall P in preds(MBB): LiveOutCache[P] == LiveOutCache[MBB]
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//
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// This is only a cache, the values can be computed as:
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//
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// VNI = LI->getVNInfoAt(LIS.getMBBEndIdx(MBB))
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// Node = mbt_[LIS.getMBBFromIndex(VNI->def)]
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//
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// The cache is also used as a visiteed set by mapValue().
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LiveOutMap LiveOutCache;
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// Dump the live-out cache to dbgs().
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void dumpCache();
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public:
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LiveIntervalMap(LiveIntervals &lis,
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MachineDominatorTree &mdt,
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const LiveInterval &parentli)
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: LIS(lis), MDT(mdt), ParentLI(parentli), LI(0) {}
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/// reset - clear all data structures and start a new live interval.
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void reset(LiveInterval *);
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/// getLI - return the current live interval.
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LiveInterval *getLI() const { return LI; }
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/// defValue - define a value in LI from the ParentLI value VNI and Idx.
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/// Idx does not have to be ParentVNI->def, but it must be contained within
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/// ParentVNI's live range in ParentLI.
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/// Return the new LI value.
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VNInfo *defValue(const VNInfo *ParentVNI, SlotIndex Idx);
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/// mapValue - map ParentVNI to the corresponding LI value at Idx. It is
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/// assumed that ParentVNI is live at Idx.
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/// If ParentVNI has not been defined by defValue, it is assumed that
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/// ParentVNI->def dominates Idx.
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/// If ParentVNI has been defined by defValue one or more times, a value that
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/// dominates Idx will be returned. This may require creating extra phi-def
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/// values and adding live ranges to LI.
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/// If simple is not NULL, *simple will indicate if ParentVNI is a simply
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/// mapped value.
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VNInfo *mapValue(const VNInfo *ParentVNI, SlotIndex Idx, bool *simple = 0);
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// extendTo - Find the last LI value defined in MBB at or before Idx. The
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// parentli is assumed to be live at Idx. Extend the live range to include
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// Idx. Return the found VNInfo, or NULL.
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VNInfo *extendTo(const MachineBasicBlock *MBB, SlotIndex Idx);
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/// isMapped - Return true is ParentVNI is a known mapped value. It may be a
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/// simple 1-1 mapping or a complex mapping to later defs.
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bool isMapped(const VNInfo *ParentVNI) const {
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return Values.count(ParentVNI);
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}
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/// isComplexMapped - Return true if ParentVNI has received new definitions
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/// with defValue.
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bool isComplexMapped(const VNInfo *ParentVNI) const;
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// addSimpleRange - Add a simple range from ParentLI to LI.
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// ParentVNI must be live in the [Start;End) interval.
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void addSimpleRange(SlotIndex Start, SlotIndex End, const VNInfo *ParentVNI);
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/// addRange - Add live ranges to LI where [Start;End) intersects ParentLI.
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/// All needed values whose def is not inside [Start;End) must be defined
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/// beforehand so mapValue will work.
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void addRange(SlotIndex Start, SlotIndex End);
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};
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/// SplitEditor - Edit machine code and LiveIntervals for live range
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/// splitting.
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///
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/// - Create a SplitEditor from a SplitAnalysis.
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/// - Start a new live interval with openIntv.
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/// - Mark the places where the new interval is entered using enterIntv*
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/// - Mark the ranges where the new interval is used with useIntv*
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/// - Mark the places where the interval is exited with exitIntv*.
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/// - Finish the current interval with closeIntv and repeat from 2.
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/// - Rewrite instructions with finish().
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///
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class SplitEditor {
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SplitAnalysis &sa_;
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LiveIntervals &LIS;
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VirtRegMap &VRM;
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MachineRegisterInfo &MRI;
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const TargetInstrInfo &TII;
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const TargetRegisterInfo &TRI;
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/// Edit - The current parent register and new intervals created.
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LiveRangeEdit &Edit;
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/// DupLI - Created as a copy of CurLI, ranges are carved out as new
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/// intervals get added through openIntv / closeIntv. This is used to avoid
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/// editing CurLI.
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LiveIntervalMap DupLI;
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/// Currently open LiveInterval.
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LiveIntervalMap OpenLI;
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/// defFromParent - Define Reg from ParentVNI at UseIdx using either
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/// rematerialization or a COPY from parent. Return the new value.
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VNInfo *defFromParent(LiveIntervalMap &Reg,
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VNInfo *ParentVNI,
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SlotIndex UseIdx,
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MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I);
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/// intervalsLiveAt - Return true if any member of intervals_ is live at Idx.
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bool intervalsLiveAt(SlotIndex Idx) const;
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/// Values in CurLI whose live range has been truncated when entering an open
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/// li.
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SmallPtrSet<const VNInfo*, 8> truncatedValues;
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/// addTruncSimpleRange - Add the given simple range to DupLI after
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/// truncating any overlap with intervals_.
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void addTruncSimpleRange(SlotIndex Start, SlotIndex End, VNInfo *VNI);
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/// criticalPreds_ - Set of basic blocks where both dupli and OpenLI should be
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/// live out because of a critical edge.
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SplitAnalysis::BlockPtrSet criticalPreds_;
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/// computeRemainder - Compute the dupli liveness as the complement of all the
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/// new intervals.
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void computeRemainder();
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/// rewrite - Rewrite all uses of reg to use the new registers.
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void rewrite(unsigned reg);
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public:
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/// Create a new SplitEditor for editing the LiveInterval analyzed by SA.
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/// Newly created intervals will be appended to newIntervals.
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SplitEditor(SplitAnalysis &SA, LiveIntervals&, VirtRegMap&,
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MachineDominatorTree&, LiveRangeEdit&);
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/// getAnalysis - Get the corresponding analysis.
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SplitAnalysis &getAnalysis() { return sa_; }
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/// Create a new virtual register and live interval.
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void openIntv();
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/// enterIntvBefore - Enter OpenLI before the instruction at Idx. If CurLI is
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/// not live before Idx, a COPY is not inserted.
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void enterIntvBefore(SlotIndex Idx);
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/// enterIntvAtEnd - Enter OpenLI at the end of MBB.
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void enterIntvAtEnd(MachineBasicBlock &MBB);
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/// useIntv - indicate that all instructions in MBB should use OpenLI.
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void useIntv(const MachineBasicBlock &MBB);
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/// useIntv - indicate that all instructions in range should use OpenLI.
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void useIntv(SlotIndex Start, SlotIndex End);
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/// leaveIntvAfter - Leave OpenLI after the instruction at Idx.
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void leaveIntvAfter(SlotIndex Idx);
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/// leaveIntvAtTop - Leave the interval at the top of MBB.
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/// Currently, only one value can leave the interval.
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void leaveIntvAtTop(MachineBasicBlock &MBB);
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/// closeIntv - Indicate that we are done editing the currently open
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/// LiveInterval, and ranges can be trimmed.
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void closeIntv();
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/// finish - after all the new live ranges have been created, compute the
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/// remaining live range, and rewrite instructions to use the new registers.
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void finish();
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// ===--- High level methods ---===
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/// splitAroundLoop - Split CurLI into a separate live interval inside
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/// the loop.
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void splitAroundLoop(const MachineLoop*);
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/// splitSingleBlocks - Split CurLI into a separate live interval inside each
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/// basic block in Blocks.
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void splitSingleBlocks(const SplitAnalysis::BlockPtrSet &Blocks);
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/// splitInsideBlock - Split CurLI into multiple intervals inside MBB.
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void splitInsideBlock(const MachineBasicBlock *);
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};
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}
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