| //=- llvm/CodeGen/GlobalISel/RegBankSelect.h - Reg Bank Selector --*- 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| /// \file This file describes the interface of the MachineFunctionPass |
| /// responsible for assigning the generic virtual registers to register bank. |
| |
| /// By default, the reg bank selector relies on local decisions to |
| /// assign the register bank. In other words, it looks at one instruction |
| /// at a time to decide where the operand of that instruction should live. |
| /// |
| /// At higher optimization level, we could imagine that the reg bank selector |
| /// would use more global analysis and do crazier thing like duplicating |
| /// instructions and so on. This is future work. |
| /// |
| /// For now, the pass uses a greedy algorithm to decide where the operand |
| /// of an instruction should live. It asks the target which banks may be |
| /// used for each operand of the instruction and what is the cost. Then, |
| /// it chooses the solution which minimize the cost of the instruction plus |
| /// the cost of any move that may be needed to the values into the right |
| /// register bank. |
| /// In other words, the cost for an instruction on a register bank RegBank |
| /// is: Cost of I on RegBank plus the sum of the cost for bringing the |
| /// input operands from their current register bank to RegBank. |
| /// Thus, the following formula: |
| /// cost(I, RegBank) = cost(I.Opcode, RegBank) + |
| /// sum(for each arg in I.arguments: costCrossCopy(arg.RegBank, RegBank)) |
| /// |
| /// E.g., Let say we are assigning the register bank for the instruction |
| /// defining v2. |
| /// v0(A_REGBANK) = ... |
| /// v1(A_REGBANK) = ... |
| /// v2 = G_ADD i32 v0, v1 <-- MI |
| /// |
| /// The target may say it can generate G_ADD i32 on register bank A and B |
| /// with a cost of respectively 5 and 1. |
| /// Then, let say the cost of a cross register bank copies from A to B is 1. |
| /// The reg bank selector would compare the following two costs: |
| /// cost(MI, A_REGBANK) = cost(G_ADD, A_REGBANK) + cost(v0.RegBank, A_REGBANK) + |
| /// cost(v1.RegBank, A_REGBANK) |
| /// = 5 + cost(A_REGBANK, A_REGBANK) + cost(A_REGBANK, |
| /// A_REGBANK) |
| /// = 5 + 0 + 0 = 5 |
| /// cost(MI, B_REGBANK) = cost(G_ADD, B_REGBANK) + cost(v0.RegBank, B_REGBANK) + |
| /// cost(v1.RegBank, B_REGBANK) |
| /// = 1 + cost(A_REGBANK, B_REGBANK) + cost(A_REGBANK, |
| /// B_REGBANK) |
| /// = 1 + 1 + 1 = 3 |
| /// Therefore, in this specific example, the reg bank selector would choose |
| /// bank B for MI. |
| /// v0(A_REGBANK) = ... |
| /// v1(A_REGBANK) = ... |
| /// tmp0(B_REGBANK) = COPY v0 |
| /// tmp1(B_REGBANK) = COPY v1 |
| /// v2(B_REGBANK) = G_ADD i32 tmp0, tmp1 |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_CODEGEN_GLOBALISEL_REGBANKSELECT_H |
| #define LLVM_CODEGEN_GLOBALISEL_REGBANKSELECT_H |
| |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/CodeGen/GlobalISel/MachineIRBuilder.h" |
| #include "llvm/CodeGen/GlobalISel/RegisterBankInfo.h" |
| #include "llvm/CodeGen/MachineBasicBlock.h" |
| #include "llvm/CodeGen/MachineFunctionPass.h" |
| #include "llvm/CodeGen/MachineOptimizationRemarkEmitter.h" |
| #include <cassert> |
| #include <cstdint> |
| #include <memory> |
| |
| namespace llvm { |
| |
| class BlockFrequency; |
| class MachineBlockFrequencyInfo; |
| class MachineBranchProbabilityInfo; |
| class MachineOperand; |
| class MachineRegisterInfo; |
| class Pass; |
| class raw_ostream; |
| class TargetPassConfig; |
| class TargetRegisterInfo; |
| |
| /// This pass implements the reg bank selector pass used in the GlobalISel |
| /// pipeline. At the end of this pass, all register operands have been assigned |
| class RegBankSelect : public MachineFunctionPass { |
| public: |
| static char ID; |
| |
| /// List of the modes supported by the RegBankSelect pass. |
| enum Mode { |
| /// Assign the register banks as fast as possible (default). |
| Fast, |
| /// Greedily minimize the cost of assigning register banks. |
| /// This should produce code of greater quality, but will |
| /// require more compile time. |
| Greedy |
| }; |
| |
| /// Abstract class used to represent an insertion point in a CFG. |
| /// This class records an insertion point and materializes it on |
| /// demand. |
| /// It allows to reason about the frequency of this insertion point, |
| /// without having to logically materialize it (e.g., on an edge), |
| /// before we actually need to insert something. |
| class InsertPoint { |
| protected: |
| /// Tell if the insert point has already been materialized. |
| bool WasMaterialized = false; |
| |
| /// Materialize the insertion point. |
| /// |
| /// If isSplit() is true, this involves actually splitting |
| /// the block or edge. |
| /// |
| /// \post getPointImpl() returns a valid iterator. |
| /// \post getInsertMBBImpl() returns a valid basic block. |
| /// \post isSplit() == false ; no more splitting should be required. |
| virtual void materialize() = 0; |
| |
| /// Return the materialized insertion basic block. |
| /// Code will be inserted into that basic block. |
| /// |
| /// \pre ::materialize has been called. |
| virtual MachineBasicBlock &getInsertMBBImpl() = 0; |
| |
| /// Return the materialized insertion point. |
| /// Code will be inserted before that point. |
| /// |
| /// \pre ::materialize has been called. |
| virtual MachineBasicBlock::iterator getPointImpl() = 0; |
| |
| public: |
| virtual ~InsertPoint() = default; |
| |
| /// The first call to this method will cause the splitting to |
| /// happen if need be, then sub sequent calls just return |
| /// the iterator to that point. I.e., no more splitting will |
| /// occur. |
| /// |
| /// \return The iterator that should be used with |
| /// MachineBasicBlock::insert. I.e., additional code happens |
| /// before that point. |
| MachineBasicBlock::iterator getPoint() { |
| if (!WasMaterialized) { |
| WasMaterialized = true; |
| assert(canMaterialize() && "Impossible to materialize this point"); |
| materialize(); |
| } |
| // When we materialized the point we should have done the splitting. |
| assert(!isSplit() && "Wrong pre-condition"); |
| return getPointImpl(); |
| } |
| |
| /// The first call to this method will cause the splitting to |
| /// happen if need be, then sub sequent calls just return |
| /// the basic block that contains the insertion point. |
| /// I.e., no more splitting will occur. |
| /// |
| /// \return The basic block should be used with |
| /// MachineBasicBlock::insert and ::getPoint. The new code should |
| /// happen before that point. |
| MachineBasicBlock &getInsertMBB() { |
| if (!WasMaterialized) { |
| WasMaterialized = true; |
| assert(canMaterialize() && "Impossible to materialize this point"); |
| materialize(); |
| } |
| // When we materialized the point we should have done the splitting. |
| assert(!isSplit() && "Wrong pre-condition"); |
| return getInsertMBBImpl(); |
| } |
| |
| /// Insert \p MI in the just before ::getPoint() |
| MachineBasicBlock::iterator insert(MachineInstr &MI) { |
| return getInsertMBB().insert(getPoint(), &MI); |
| } |
| |
| /// Does this point involve splitting an edge or block? |
| /// As soon as ::getPoint is called and thus, the point |
| /// materialized, the point will not require splitting anymore, |
| /// i.e., this will return false. |
| virtual bool isSplit() const { return false; } |
| |
| /// Frequency of the insertion point. |
| /// \p P is used to access the various analysis that will help to |
| /// get that information, like MachineBlockFrequencyInfo. If \p P |
| /// does not contain enough enough to return the actual frequency, |
| /// this returns 1. |
| virtual uint64_t frequency(const Pass &P) const { return 1; } |
| |
| /// Check whether this insertion point can be materialized. |
| /// As soon as ::getPoint is called and thus, the point materialized |
| /// calling this method does not make sense. |
| virtual bool canMaterialize() const { return false; } |
| }; |
| |
| /// Insertion point before or after an instruction. |
| class InstrInsertPoint : public InsertPoint { |
| private: |
| /// Insertion point. |
| MachineInstr &Instr; |
| |
| /// Does the insertion point is before or after Instr. |
| bool Before; |
| |
| void materialize() override; |
| |
| MachineBasicBlock::iterator getPointImpl() override { |
| if (Before) |
| return Instr; |
| return Instr.getNextNode() ? *Instr.getNextNode() |
| : Instr.getParent()->end(); |
| } |
| |
| MachineBasicBlock &getInsertMBBImpl() override { |
| return *Instr.getParent(); |
| } |
| |
| public: |
| /// Create an insertion point before (\p Before=true) or after \p Instr. |
| InstrInsertPoint(MachineInstr &Instr, bool Before = true); |
| |
| bool isSplit() const override; |
| uint64_t frequency(const Pass &P) const override; |
| |
| // Worst case, we need to slice the basic block, but that is still doable. |
| bool canMaterialize() const override { return true; } |
| }; |
| |
| /// Insertion point at the beginning or end of a basic block. |
| class MBBInsertPoint : public InsertPoint { |
| private: |
| /// Insertion point. |
| MachineBasicBlock &MBB; |
| |
| /// Does the insertion point is at the beginning or end of MBB. |
| bool Beginning; |
| |
| void materialize() override { /*Nothing to do to materialize*/ |
| } |
| |
| MachineBasicBlock::iterator getPointImpl() override { |
| return Beginning ? MBB.begin() : MBB.end(); |
| } |
| |
| MachineBasicBlock &getInsertMBBImpl() override { return MBB; } |
| |
| public: |
| MBBInsertPoint(MachineBasicBlock &MBB, bool Beginning = true) |
| : InsertPoint(), MBB(MBB), Beginning(Beginning) { |
| // If we try to insert before phis, we should use the insertion |
| // points on the incoming edges. |
| assert((!Beginning || MBB.getFirstNonPHI() == MBB.begin()) && |
| "Invalid beginning point"); |
| // If we try to insert after the terminators, we should use the |
| // points on the outcoming edges. |
| assert((Beginning || MBB.getFirstTerminator() == MBB.end()) && |
| "Invalid end point"); |
| } |
| |
| bool isSplit() const override { return false; } |
| uint64_t frequency(const Pass &P) const override; |
| bool canMaterialize() const override { return true; }; |
| }; |
| |
| /// Insertion point on an edge. |
| class EdgeInsertPoint : public InsertPoint { |
| private: |
| /// Source of the edge. |
| MachineBasicBlock &Src; |
| |
| /// Destination of the edge. |
| /// After the materialization is done, this hold the basic block |
| /// that resulted from the splitting. |
| MachineBasicBlock *DstOrSplit; |
| |
| /// P is used to update the analysis passes as applicable. |
| Pass &P; |
| |
| void materialize() override; |
| |
| MachineBasicBlock::iterator getPointImpl() override { |
| // DstOrSplit should be the Split block at this point. |
| // I.e., it should have one predecessor, Src, and one successor, |
| // the original Dst. |
| assert(DstOrSplit && DstOrSplit->isPredecessor(&Src) && |
| DstOrSplit->pred_size() == 1 && DstOrSplit->succ_size() == 1 && |
| "Did not split?!"); |
| return DstOrSplit->begin(); |
| } |
| |
| MachineBasicBlock &getInsertMBBImpl() override { return *DstOrSplit; } |
| |
| public: |
| EdgeInsertPoint(MachineBasicBlock &Src, MachineBasicBlock &Dst, Pass &P) |
| : InsertPoint(), Src(Src), DstOrSplit(&Dst), P(P) {} |
| |
| bool isSplit() const override { |
| return Src.succ_size() > 1 && DstOrSplit->pred_size() > 1; |
| } |
| |
| uint64_t frequency(const Pass &P) const override; |
| bool canMaterialize() const override; |
| }; |
| |
| /// Struct used to represent the placement of a repairing point for |
| /// a given operand. |
| class RepairingPlacement { |
| public: |
| /// Define the kind of action this repairing needs. |
| enum RepairingKind { |
| /// Nothing to repair, just drop this action. |
| None, |
| /// Reparing code needs to happen before InsertPoints. |
| Insert, |
| /// (Re)assign the register bank of the operand. |
| Reassign, |
| /// Mark this repairing placement as impossible. |
| Impossible |
| }; |
| |
| /// \name Convenient types for a list of insertion points. |
| /// @{ |
| using InsertionPoints = SmallVector<std::unique_ptr<InsertPoint>, 2>; |
| using insertpt_iterator = InsertionPoints::iterator; |
| using const_insertpt_iterator = InsertionPoints::const_iterator; |
| /// @} |
| |
| private: |
| /// Kind of repairing. |
| RepairingKind Kind; |
| /// Index of the operand that will be repaired. |
| unsigned OpIdx; |
| /// Are all the insert points materializeable? |
| bool CanMaterialize; |
| /// Is there any of the insert points needing splitting? |
| bool HasSplit = false; |
| /// Insertion point for the repair code. |
| /// The repairing code needs to happen just before these points. |
| InsertionPoints InsertPoints; |
| /// Some insertion points may need to update the liveness and such. |
| Pass &P; |
| |
| public: |
| /// Create a repairing placement for the \p OpIdx-th operand of |
| /// \p MI. \p TRI is used to make some checks on the register aliases |
| /// if the machine operand is a physical register. \p P is used to |
| /// to update liveness information and such when materializing the |
| /// points. |
| RepairingPlacement(MachineInstr &MI, unsigned OpIdx, |
| const TargetRegisterInfo &TRI, Pass &P, |
| RepairingKind Kind = RepairingKind::Insert); |
| |
| /// \name Getters. |
| /// @{ |
| RepairingKind getKind() const { return Kind; } |
| unsigned getOpIdx() const { return OpIdx; } |
| bool canMaterialize() const { return CanMaterialize; } |
| bool hasSplit() { return HasSplit; } |
| /// @} |
| |
| /// \name Overloaded methods to add an insertion point. |
| /// @{ |
| /// Add a MBBInsertionPoint to the list of InsertPoints. |
| void addInsertPoint(MachineBasicBlock &MBB, bool Beginning); |
| /// Add a InstrInsertionPoint to the list of InsertPoints. |
| void addInsertPoint(MachineInstr &MI, bool Before); |
| /// Add an EdgeInsertionPoint (\p Src, \p Dst) to the list of InsertPoints. |
| void addInsertPoint(MachineBasicBlock &Src, MachineBasicBlock &Dst); |
| /// Add an InsertPoint to the list of insert points. |
| /// This method takes the ownership of &\p Point. |
| void addInsertPoint(InsertPoint &Point); |
| /// @} |
| |
| /// \name Accessors related to the insertion points. |
| /// @{ |
| insertpt_iterator begin() { return InsertPoints.begin(); } |
| insertpt_iterator end() { return InsertPoints.end(); } |
| |
| const_insertpt_iterator begin() const { return InsertPoints.begin(); } |
| const_insertpt_iterator end() const { return InsertPoints.end(); } |
| |
| unsigned getNumInsertPoints() const { return InsertPoints.size(); } |
| /// @} |
| |
| /// Change the type of this repairing placement to \p NewKind. |
| /// It is not possible to switch a repairing placement to the |
| /// RepairingKind::Insert. There is no fundamental problem with |
| /// that, but no uses as well, so do not support it for now. |
| /// |
| /// \pre NewKind != RepairingKind::Insert |
| /// \post getKind() == NewKind |
| void switchTo(RepairingKind NewKind) { |
| assert(NewKind != Kind && "Already of the right Kind"); |
| Kind = NewKind; |
| InsertPoints.clear(); |
| CanMaterialize = NewKind != RepairingKind::Impossible; |
| HasSplit = false; |
| assert(NewKind != RepairingKind::Insert && |
| "We would need more MI to switch to Insert"); |
| } |
| }; |
| |
| private: |
| /// Helper class used to represent the cost for mapping an instruction. |
| /// When mapping an instruction, we may introduce some repairing code. |
| /// In most cases, the repairing code is local to the instruction, |
| /// thus, we can omit the basic block frequency from the cost. |
| /// However, some alternatives may produce non-local cost, e.g., when |
| /// repairing a phi, and thus we then need to scale the local cost |
| /// to the non-local cost. This class does this for us. |
| /// \note: We could simply always scale the cost. The problem is that |
| /// there are higher chances that we saturate the cost easier and end |
| /// up having the same cost for actually different alternatives. |
| /// Another option would be to use APInt everywhere. |
| class MappingCost { |
| private: |
| /// Cost of the local instructions. |
| /// This cost is free of basic block frequency. |
| uint64_t LocalCost = 0; |
| /// Cost of the non-local instructions. |
| /// This cost should include the frequency of the related blocks. |
| uint64_t NonLocalCost = 0; |
| /// Frequency of the block where the local instructions live. |
| uint64_t LocalFreq; |
| |
| MappingCost(uint64_t LocalCost, uint64_t NonLocalCost, uint64_t LocalFreq) |
| : LocalCost(LocalCost), NonLocalCost(NonLocalCost), |
| LocalFreq(LocalFreq) {} |
| |
| /// Check if this cost is saturated. |
| bool isSaturated() const; |
| |
| public: |
| /// Create a MappingCost assuming that most of the instructions |
| /// will occur in a basic block with \p LocalFreq frequency. |
| MappingCost(const BlockFrequency &LocalFreq); |
| |
| /// Add \p Cost to the local cost. |
| /// \return true if this cost is saturated, false otherwise. |
| bool addLocalCost(uint64_t Cost); |
| |
| /// Add \p Cost to the non-local cost. |
| /// Non-local cost should reflect the frequency of their placement. |
| /// \return true if this cost is saturated, false otherwise. |
| bool addNonLocalCost(uint64_t Cost); |
| |
| /// Saturate the cost to the maximal representable value. |
| void saturate(); |
| |
| /// Return an instance of MappingCost that represents an |
| /// impossible mapping. |
| static MappingCost ImpossibleCost(); |
| |
| /// Check if this is less than \p Cost. |
| bool operator<(const MappingCost &Cost) const; |
| /// Check if this is equal to \p Cost. |
| bool operator==(const MappingCost &Cost) const; |
| /// Check if this is not equal to \p Cost. |
| bool operator!=(const MappingCost &Cost) const { return !(*this == Cost); } |
| /// Check if this is greater than \p Cost. |
| bool operator>(const MappingCost &Cost) const { |
| return *this != Cost && Cost < *this; |
| } |
| |
| /// Print this on dbgs() stream. |
| void dump() const; |
| |
| /// Print this on \p OS; |
| void print(raw_ostream &OS) const; |
| |
| /// Overload the stream operator for easy debug printing. |
| friend raw_ostream &operator<<(raw_ostream &OS, const MappingCost &Cost) { |
| Cost.print(OS); |
| return OS; |
| } |
| }; |
| |
| /// Interface to the target lowering info related |
| /// to register banks. |
| const RegisterBankInfo *RBI = nullptr; |
| |
| /// MRI contains all the register class/bank information that this |
| /// pass uses and updates. |
| MachineRegisterInfo *MRI = nullptr; |
| |
| /// Information on the register classes for the current function. |
| const TargetRegisterInfo *TRI = nullptr; |
| |
| /// Get the frequency of blocks. |
| /// This is required for non-fast mode. |
| MachineBlockFrequencyInfo *MBFI = nullptr; |
| |
| /// Get the frequency of the edges. |
| /// This is required for non-fast mode. |
| MachineBranchProbabilityInfo *MBPI = nullptr; |
| |
| /// Current optimization remark emitter. Used to report failures. |
| std::unique_ptr<MachineOptimizationRemarkEmitter> MORE; |
| |
| /// Helper class used for every code morphing. |
| MachineIRBuilder MIRBuilder; |
| |
| /// Optimization mode of the pass. |
| Mode OptMode; |
| |
| /// Current target configuration. Controls how the pass handles errors. |
| const TargetPassConfig *TPC; |
| |
| /// Assign the register bank of each operand of \p MI. |
| /// \return True on success, false otherwise. |
| bool assignInstr(MachineInstr &MI); |
| |
| /// Initialize the field members using \p MF. |
| void init(MachineFunction &MF); |
| |
| /// Check if \p Reg is already assigned what is described by \p ValMapping. |
| /// \p OnlyAssign == true means that \p Reg just needs to be assigned a |
| /// register bank. I.e., no repairing is necessary to have the |
| /// assignment match. |
| bool assignmentMatch(unsigned Reg, |
| const RegisterBankInfo::ValueMapping &ValMapping, |
| bool &OnlyAssign) const; |
| |
| /// Insert repairing code for \p Reg as specified by \p ValMapping. |
| /// The repairing placement is specified by \p RepairPt. |
| /// \p NewVRegs contains all the registers required to remap \p Reg. |
| /// In other words, the number of registers in NewVRegs must be equal |
| /// to ValMapping.BreakDown.size(). |
| /// |
| /// The transformation could be sketched as: |
| /// \code |
| /// ... = op Reg |
| /// \endcode |
| /// Becomes |
| /// \code |
| /// <NewRegs> = COPY or extract Reg |
| /// ... = op Reg |
| /// \endcode |
| /// |
| /// and |
| /// \code |
| /// Reg = op ... |
| /// \endcode |
| /// Becomes |
| /// \code |
| /// Reg = op ... |
| /// Reg = COPY or build_sequence <NewRegs> |
| /// \endcode |
| /// |
| /// \pre NewVRegs.size() == ValMapping.BreakDown.size() |
| /// |
| /// \note The caller is supposed to do the rewriting of op if need be. |
| /// I.e., Reg = op ... => <NewRegs> = NewOp ... |
| /// |
| /// \return True if the repairing worked, false otherwise. |
| bool repairReg(MachineOperand &MO, |
| const RegisterBankInfo::ValueMapping &ValMapping, |
| RegBankSelect::RepairingPlacement &RepairPt, |
| const iterator_range<SmallVectorImpl<unsigned>::const_iterator> |
| &NewVRegs); |
| |
| /// Return the cost of the instruction needed to map \p MO to \p ValMapping. |
| /// The cost is free of basic block frequencies. |
| /// \pre MO.isReg() |
| /// \pre MO is assigned to a register bank. |
| /// \pre ValMapping is a valid mapping for MO. |
| uint64_t |
| getRepairCost(const MachineOperand &MO, |
| const RegisterBankInfo::ValueMapping &ValMapping) const; |
| |
| /// Find the best mapping for \p MI from \p PossibleMappings. |
| /// \return a reference on the best mapping in \p PossibleMappings. |
| const RegisterBankInfo::InstructionMapping & |
| findBestMapping(MachineInstr &MI, |
| RegisterBankInfo::InstructionMappings &PossibleMappings, |
| SmallVectorImpl<RepairingPlacement> &RepairPts); |
| |
| /// Compute the cost of mapping \p MI with \p InstrMapping and |
| /// compute the repairing placement for such mapping in \p |
| /// RepairPts. |
| /// \p BestCost is used to specify when the cost becomes too high |
| /// and thus it is not worth computing the RepairPts. Moreover if |
| /// \p BestCost == nullptr, the mapping cost is actually not |
| /// computed. |
| MappingCost |
| computeMapping(MachineInstr &MI, |
| const RegisterBankInfo::InstructionMapping &InstrMapping, |
| SmallVectorImpl<RepairingPlacement> &RepairPts, |
| const MappingCost *BestCost = nullptr); |
| |
| /// When \p RepairPt involves splitting to repair \p MO for the |
| /// given \p ValMapping, try to change the way we repair such that |
| /// the splitting is not required anymore. |
| /// |
| /// \pre \p RepairPt.hasSplit() |
| /// \pre \p MO == MO.getParent()->getOperand(\p RepairPt.getOpIdx()) |
| /// \pre \p ValMapping is the mapping of \p MO for MO.getParent() |
| /// that implied \p RepairPt. |
| void tryAvoidingSplit(RegBankSelect::RepairingPlacement &RepairPt, |
| const MachineOperand &MO, |
| const RegisterBankInfo::ValueMapping &ValMapping) const; |
| |
| /// Apply \p Mapping to \p MI. \p RepairPts represents the different |
| /// mapping action that need to happen for the mapping to be |
| /// applied. |
| /// \return True if the mapping was applied sucessfully, false otherwise. |
| bool applyMapping(MachineInstr &MI, |
| const RegisterBankInfo::InstructionMapping &InstrMapping, |
| SmallVectorImpl<RepairingPlacement> &RepairPts); |
| |
| public: |
| /// Create a RegBankSelect pass with the specified \p RunningMode. |
| RegBankSelect(Mode RunningMode = Fast); |
| |
| StringRef getPassName() const override { return "RegBankSelect"; } |
| |
| void getAnalysisUsage(AnalysisUsage &AU) const override; |
| |
| MachineFunctionProperties getRequiredProperties() const override { |
| return MachineFunctionProperties() |
| .set(MachineFunctionProperties::Property::IsSSA) |
| .set(MachineFunctionProperties::Property::Legalized); |
| } |
| |
| MachineFunctionProperties getSetProperties() const override { |
| return MachineFunctionProperties().set( |
| MachineFunctionProperties::Property::RegBankSelected); |
| } |
| |
| /// Walk through \p MF and assign a register bank to every virtual register |
| /// that are still mapped to nothing. |
| /// The target needs to provide a RegisterBankInfo and in particular |
| /// override RegisterBankInfo::getInstrMapping. |
| /// |
| /// Simplified algo: |
| /// \code |
| /// RBI = MF.subtarget.getRegBankInfo() |
| /// MIRBuilder.setMF(MF) |
| /// for each bb in MF |
| /// for each inst in bb |
| /// MIRBuilder.setInstr(inst) |
| /// MappingCosts = RBI.getMapping(inst); |
| /// Idx = findIdxOfMinCost(MappingCosts) |
| /// CurRegBank = MappingCosts[Idx].RegBank |
| /// MRI.setRegBank(inst.getOperand(0).getReg(), CurRegBank) |
| /// for each argument in inst |
| /// if (CurRegBank != argument.RegBank) |
| /// ArgReg = argument.getReg() |
| /// Tmp = MRI.createNewVirtual(MRI.getSize(ArgReg), CurRegBank) |
| /// MIRBuilder.buildInstr(COPY, Tmp, ArgReg) |
| /// inst.getOperand(argument.getOperandNo()).setReg(Tmp) |
| /// \endcode |
| bool runOnMachineFunction(MachineFunction &MF) override; |
| }; |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_CODEGEN_GLOBALISEL_REGBANKSELECT_H |