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Diffstat (limited to 'lib/CodeGen/LiveRangeCalc.h')
| -rw-r--r-- | lib/CodeGen/LiveRangeCalc.h | 297 |
1 files changed, 0 insertions, 297 deletions
diff --git a/lib/CodeGen/LiveRangeCalc.h b/lib/CodeGen/LiveRangeCalc.h deleted file mode 100644 index 11aea5a3b016..000000000000 --- a/lib/CodeGen/LiveRangeCalc.h +++ /dev/null @@ -1,297 +0,0 @@ -//===- LiveRangeCalc.h - Calculate live ranges ------------------*- C++ -*-===// -// -// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. -// See https://llvm.org/LICENSE.txt for license information. -// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception -// -//===----------------------------------------------------------------------===// -// -// The LiveRangeCalc class can be used to compute live ranges from scratch. It -// caches information about values in the CFG to speed up repeated operations -// on the same live range. The cache can be shared by non-overlapping live -// ranges. SplitKit uses that when computing the live range of split products. -// -// A low-level interface is available to clients that know where a variable is -// live, but don't know which value it has as every point. LiveRangeCalc will -// propagate values down the dominator tree, and even insert PHI-defs where -// needed. SplitKit uses this faster interface when possible. -// -//===----------------------------------------------------------------------===// - -#ifndef LLVM_LIB_CODEGEN_LIVERANGECALC_H -#define LLVM_LIB_CODEGEN_LIVERANGECALC_H - -#include "llvm/ADT/ArrayRef.h" -#include "llvm/ADT/BitVector.h" -#include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/IndexedMap.h" -#include "llvm/ADT/SmallVector.h" -#include "llvm/CodeGen/LiveInterval.h" -#include "llvm/CodeGen/MachineBasicBlock.h" -#include "llvm/CodeGen/SlotIndexes.h" -#include "llvm/MC/LaneBitmask.h" -#include <utility> - -namespace llvm { - -template <class NodeT> class DomTreeNodeBase; -class MachineDominatorTree; -class MachineFunction; -class MachineRegisterInfo; - -using MachineDomTreeNode = DomTreeNodeBase<MachineBasicBlock>; - -class LiveRangeCalc { - const MachineFunction *MF = nullptr; - const MachineRegisterInfo *MRI = nullptr; - SlotIndexes *Indexes = nullptr; - MachineDominatorTree *DomTree = nullptr; - VNInfo::Allocator *Alloc = nullptr; - - /// LiveOutPair - A value and the block that defined it. The domtree node is - /// redundant, it can be computed as: MDT[Indexes.getMBBFromIndex(VNI->def)]. - using LiveOutPair = std::pair<VNInfo *, MachineDomTreeNode *>; - - /// LiveOutMap - Map basic blocks to the value leaving the block. - using LiveOutMap = IndexedMap<LiveOutPair, MBB2NumberFunctor>; - - /// Bit vector of active entries in LiveOut, also used as a visited set by - /// findReachingDefs. One entry per basic block, indexed by block number. - /// This is kept as a separate bit vector because it can be cleared quickly - /// when switching live ranges. - BitVector Seen; - - /// Map LiveRange to sets of blocks (represented by bit vectors) that - /// in the live range are defined on entry and undefined on entry. - /// A block is defined on entry if there is a path from at least one of - /// the defs in the live range to the entry of the block, and conversely, - /// a block is undefined on entry, if there is no such path (i.e. no - /// definition reaches the entry of the block). A single LiveRangeCalc - /// object is used to track live-out information for multiple registers - /// in live range splitting (which is ok, since the live ranges of these - /// registers do not overlap), but the defined/undefined information must - /// be kept separate for each individual range. - /// By convention, EntryInfoMap[&LR] = { Defined, Undefined }. - using EntryInfoMap = DenseMap<LiveRange *, std::pair<BitVector, BitVector>>; - EntryInfoMap EntryInfos; - - /// Map each basic block where a live range is live out to the live-out value - /// and its defining block. - /// - /// For every basic block, MBB, one of these conditions shall be true: - /// - /// 1. !Seen.count(MBB->getNumber()) - /// Blocks without a Seen bit are ignored. - /// 2. LiveOut[MBB].second.getNode() == MBB - /// The live-out value is defined in MBB. - /// 3. forall P in preds(MBB): LiveOut[P] == LiveOut[MBB] - /// The live-out value passses through MBB. All predecessors must carry - /// the same value. - /// - /// The domtree node may be null, it can be computed. - /// - /// The map can be shared by multiple live ranges as long as no two are - /// live-out of the same block. - LiveOutMap Map; - - /// LiveInBlock - Information about a basic block where a live range is known - /// to be live-in, but the value has not yet been determined. - struct LiveInBlock { - // The live range set that is live-in to this block. The algorithms can - // handle multiple non-overlapping live ranges simultaneously. - LiveRange &LR; - - // DomNode - Dominator tree node for the block. - // Cleared when the final value has been determined and LI has been updated. - MachineDomTreeNode *DomNode; - - // Position in block where the live-in range ends, or SlotIndex() if the - // range passes through the block. When the final value has been - // determined, the range from the block start to Kill will be added to LI. - SlotIndex Kill; - - // Live-in value filled in by updateSSA once it is known. - VNInfo *Value = nullptr; - - LiveInBlock(LiveRange &LR, MachineDomTreeNode *node, SlotIndex kill) - : LR(LR), DomNode(node), Kill(kill) {} - }; - - /// LiveIn - Work list of blocks where the live-in value has yet to be - /// determined. This list is typically computed by findReachingDefs() and - /// used as a work list by updateSSA(). The low-level interface may also be - /// used to add entries directly. - SmallVector<LiveInBlock, 16> LiveIn; - - /// Check if the entry to block @p MBB can be reached by any of the defs - /// in @p LR. Return true if none of the defs reach the entry to @p MBB. - bool isDefOnEntry(LiveRange &LR, ArrayRef<SlotIndex> Undefs, - MachineBasicBlock &MBB, BitVector &DefOnEntry, - BitVector &UndefOnEntry); - - /// Find the set of defs that can reach @p Kill. @p Kill must belong to - /// @p UseMBB. - /// - /// If exactly one def can reach @p UseMBB, and the def dominates @p Kill, - /// all paths from the def to @p UseMBB are added to @p LR, and the function - /// returns true. - /// - /// If multiple values can reach @p UseMBB, the blocks that need @p LR to be - /// live in are added to the LiveIn array, and the function returns false. - /// - /// The array @p Undef provides the locations where the range @p LR becomes - /// undefined by <def,read-undef> operands on other subranges. If @p Undef - /// is non-empty and @p Kill is jointly dominated only by the entries of - /// @p Undef, the function returns false. - /// - /// PhysReg, when set, is used to verify live-in lists on basic blocks. - bool findReachingDefs(LiveRange &LR, MachineBasicBlock &UseMBB, - SlotIndex Use, unsigned PhysReg, - ArrayRef<SlotIndex> Undefs); - - /// updateSSA - Compute the values that will be live in to all requested - /// blocks in LiveIn. Create PHI-def values as required to preserve SSA form. - /// - /// Every live-in block must be jointly dominated by the added live-out - /// blocks. No values are read from the live ranges. - void updateSSA(); - - /// Transfer information from the LiveIn vector to the live ranges and update - /// the given @p LiveOuts. - void updateFromLiveIns(); - - /// Extend the live range of @p LR to reach all uses of Reg. - /// - /// If @p LR is a main range, or if @p LI is null, then all uses must be - /// jointly dominated by the definitions from @p LR. If @p LR is a subrange - /// of the live interval @p LI, corresponding to lane mask @p LaneMask, - /// all uses must be jointly dominated by the definitions from @p LR - /// together with definitions of other lanes where @p LR becomes undefined - /// (via <def,read-undef> operands). - /// If @p LR is a main range, the @p LaneMask should be set to ~0, i.e. - /// LaneBitmask::getAll(). - void extendToUses(LiveRange &LR, unsigned Reg, LaneBitmask LaneMask, - LiveInterval *LI = nullptr); - - /// Reset Map and Seen fields. - void resetLiveOutMap(); - -public: - LiveRangeCalc() = default; - - //===--------------------------------------------------------------------===// - // High-level interface. - //===--------------------------------------------------------------------===// - // - // Calculate live ranges from scratch. - // - - /// reset - Prepare caches for a new set of non-overlapping live ranges. The - /// caches must be reset before attempting calculations with a live range - /// that may overlap a previously computed live range, and before the first - /// live range in a function. If live ranges are not known to be - /// non-overlapping, call reset before each. - void reset(const MachineFunction *mf, SlotIndexes *SI, - MachineDominatorTree *MDT, VNInfo::Allocator *VNIA); - - //===--------------------------------------------------------------------===// - // Mid-level interface. - //===--------------------------------------------------------------------===// - // - // Modify existing live ranges. - // - - /// Extend the live range of @p LR to reach @p Use. - /// - /// The existing values in @p LR must be live so they jointly dominate @p Use. - /// If @p Use is not dominated by a single existing value, PHI-defs are - /// inserted as required to preserve SSA form. - /// - /// PhysReg, when set, is used to verify live-in lists on basic blocks. - void extend(LiveRange &LR, SlotIndex Use, unsigned PhysReg, - ArrayRef<SlotIndex> Undefs); - - /// createDeadDefs - Create a dead def in LI for every def operand of Reg. - /// Each instruction defining Reg gets a new VNInfo with a corresponding - /// minimal live range. - void createDeadDefs(LiveRange &LR, unsigned Reg); - - /// Extend the live range of @p LR to reach all uses of Reg. - /// - /// All uses must be jointly dominated by existing liveness. PHI-defs are - /// inserted as needed to preserve SSA form. - void extendToUses(LiveRange &LR, unsigned PhysReg) { - extendToUses(LR, PhysReg, LaneBitmask::getAll()); - } - - /// Calculates liveness for the register specified in live interval @p LI. - /// Creates subregister live ranges as needed if subreg liveness tracking is - /// enabled. - void calculate(LiveInterval &LI, bool TrackSubRegs); - - /// For live interval \p LI with correct SubRanges construct matching - /// information for the main live range. Expects the main live range to not - /// have any segments or value numbers. - void constructMainRangeFromSubranges(LiveInterval &LI); - - //===--------------------------------------------------------------------===// - // Low-level interface. - //===--------------------------------------------------------------------===// - // - // These functions can be used to compute live ranges where the live-in and - // live-out blocks are already known, but the SSA value in each block is - // unknown. - // - // After calling reset(), add known live-out values and known live-in blocks. - // Then call calculateValues() to compute the actual value that is - // live-in to each block, and add liveness to the live ranges. - // - - /// setLiveOutValue - Indicate that VNI is live out from MBB. The - /// calculateValues() function will not add liveness for MBB, the caller - /// should take care of that. - /// - /// VNI may be null only if MBB is a live-through block also passed to - /// addLiveInBlock(). - void setLiveOutValue(MachineBasicBlock *MBB, VNInfo *VNI) { - Seen.set(MBB->getNumber()); - Map[MBB] = LiveOutPair(VNI, nullptr); - } - - /// addLiveInBlock - Add a block with an unknown live-in value. This - /// function can only be called once per basic block. Once the live-in value - /// has been determined, calculateValues() will add liveness to LI. - /// - /// @param LR The live range that is live-in to the block. - /// @param DomNode The domtree node for the block. - /// @param Kill Index in block where LI is killed. If the value is - /// live-through, set Kill = SLotIndex() and also call - /// setLiveOutValue(MBB, 0). - void addLiveInBlock(LiveRange &LR, - MachineDomTreeNode *DomNode, - SlotIndex Kill = SlotIndex()) { - LiveIn.push_back(LiveInBlock(LR, DomNode, Kill)); - } - - /// calculateValues - Calculate the value that will be live-in to each block - /// added with addLiveInBlock. Add PHI-def values as needed to preserve SSA - /// form. Add liveness to all live-in blocks up to the Kill point, or the - /// whole block for live-through blocks. - /// - /// Every predecessor of a live-in block must have been given a value with - /// setLiveOutValue, the value may be null for live-trough blocks. - void calculateValues(); - - /// A diagnostic function to check if the end of the block @p MBB is - /// jointly dominated by the blocks corresponding to the slot indices - /// in @p Defs. This function is mainly for use in self-verification - /// checks. - LLVM_ATTRIBUTE_UNUSED - static bool isJointlyDominated(const MachineBasicBlock *MBB, - ArrayRef<SlotIndex> Defs, - const SlotIndexes &Indexes); -}; - -} // end namespace llvm - -#endif // LLVM_LIB_CODEGEN_LIVERANGECALC_H |