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  1. //===- llvm/CodeGen/MachineFunction.h ---------------------------*- C++ -*-===//
  2. //
  3. // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
  4. // See https://llvm.org/LICENSE.txt for license information.
  5. // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
  6. //
  7. //===----------------------------------------------------------------------===//
  8. //
  9. // Collect native machine code for a function.  This class contains a list of
  10. // MachineBasicBlock instances that make up the current compiled function.
  11. //
  12. // This class also contains pointers to various classes which hold
  13. // target-specific information about the generated code.
  14. //
  15. //===----------------------------------------------------------------------===//
  16.  
  17. #ifndef LLVM_CODEGEN_MACHINEFUNCTION_H
  18. #define LLVM_CODEGEN_MACHINEFUNCTION_H
  19.  
  20. #include "llvm/ADT/ArrayRef.h"
  21. #include "llvm/ADT/BitVector.h"
  22. #include "llvm/ADT/DenseMap.h"
  23. #include "llvm/ADT/GraphTraits.h"
  24. #include "llvm/ADT/SmallVector.h"
  25. #include "llvm/ADT/ilist.h"
  26. #include "llvm/ADT/iterator.h"
  27. #include "llvm/Analysis/EHPersonalities.h"
  28. #include "llvm/CodeGen/MachineBasicBlock.h"
  29. #include "llvm/CodeGen/MachineInstr.h"
  30. #include "llvm/CodeGen/MachineMemOperand.h"
  31. #include "llvm/Support/Allocator.h"
  32. #include "llvm/Support/ArrayRecycler.h"
  33. #include "llvm/Support/AtomicOrdering.h"
  34. #include "llvm/Support/Compiler.h"
  35. #include "llvm/Support/Recycler.h"
  36. #include "llvm/Target/TargetOptions.h"
  37. #include <cassert>
  38. #include <cstdint>
  39. #include <memory>
  40. #include <utility>
  41. #include <vector>
  42.  
  43. namespace llvm {
  44.  
  45. class BasicBlock;
  46. class BlockAddress;
  47. class DataLayout;
  48. class DebugLoc;
  49. struct DenormalMode;
  50. class DIExpression;
  51. class DILocalVariable;
  52. class DILocation;
  53. class Function;
  54. class GISelChangeObserver;
  55. class GlobalValue;
  56. class LLVMTargetMachine;
  57. class MachineConstantPool;
  58. class MachineFrameInfo;
  59. class MachineFunction;
  60. class MachineJumpTableInfo;
  61. class MachineModuleInfo;
  62. class MachineRegisterInfo;
  63. class MCContext;
  64. class MCInstrDesc;
  65. class MCSymbol;
  66. class MCSection;
  67. class Pass;
  68. class PseudoSourceValueManager;
  69. class raw_ostream;
  70. class SlotIndexes;
  71. class StringRef;
  72. class TargetRegisterClass;
  73. class TargetSubtargetInfo;
  74. struct WasmEHFuncInfo;
  75. struct WinEHFuncInfo;
  76.  
  77. template <> struct ilist_alloc_traits<MachineBasicBlock> {
  78.   void deleteNode(MachineBasicBlock *MBB);
  79. };
  80.  
  81. template <> struct ilist_callback_traits<MachineBasicBlock> {
  82.   void addNodeToList(MachineBasicBlock* N);
  83.   void removeNodeFromList(MachineBasicBlock* N);
  84.  
  85.   template <class Iterator>
  86.   void transferNodesFromList(ilist_callback_traits &OldList, Iterator, Iterator) {
  87.     assert(this == &OldList && "never transfer MBBs between functions");
  88.   }
  89. };
  90.  
  91. /// MachineFunctionInfo - This class can be derived from and used by targets to
  92. /// hold private target-specific information for each MachineFunction.  Objects
  93. /// of type are accessed/created with MF::getInfo and destroyed when the
  94. /// MachineFunction is destroyed.
  95. struct MachineFunctionInfo {
  96.   virtual ~MachineFunctionInfo();
  97.  
  98.   /// Factory function: default behavior is to call new using the
  99.   /// supplied allocator.
  100.   ///
  101.   /// This function can be overridden in a derive class.
  102.   template <typename FuncInfoTy, typename SubtargetTy = TargetSubtargetInfo>
  103.   static FuncInfoTy *create(BumpPtrAllocator &Allocator, const Function &F,
  104.                             const SubtargetTy *STI) {
  105.     return new (Allocator.Allocate<FuncInfoTy>()) FuncInfoTy(F, STI);
  106.   }
  107.  
  108.   template <typename Ty>
  109.   static Ty *create(BumpPtrAllocator &Allocator, const Ty &MFI) {
  110.     return new (Allocator.Allocate<Ty>()) Ty(MFI);
  111.   }
  112.  
  113.   /// Make a functionally equivalent copy of this MachineFunctionInfo in \p MF.
  114.   /// This requires remapping MachineBasicBlock references from the original
  115.   /// parent to values in the new function. Targets may assume that virtual
  116.   /// register and frame index values are preserved in the new function.
  117.   virtual MachineFunctionInfo *
  118.   clone(BumpPtrAllocator &Allocator, MachineFunction &DestMF,
  119.         const DenseMap<MachineBasicBlock *, MachineBasicBlock *> &Src2DstMBB)
  120.       const {
  121.     return nullptr;
  122.   }
  123. };
  124.  
  125. /// Properties which a MachineFunction may have at a given point in time.
  126. /// Each of these has checking code in the MachineVerifier, and passes can
  127. /// require that a property be set.
  128. class MachineFunctionProperties {
  129.   // Possible TODO: Allow targets to extend this (perhaps by allowing the
  130.   // constructor to specify the size of the bit vector)
  131.   // Possible TODO: Allow requiring the negative (e.g. VRegsAllocated could be
  132.   // stated as the negative of "has vregs"
  133.  
  134. public:
  135.   // The properties are stated in "positive" form; i.e. a pass could require
  136.   // that the property hold, but not that it does not hold.
  137.  
  138.   // Property descriptions:
  139.   // IsSSA: True when the machine function is in SSA form and virtual registers
  140.   //  have a single def.
  141.   // NoPHIs: The machine function does not contain any PHI instruction.
  142.   // TracksLiveness: True when tracking register liveness accurately.
  143.   //  While this property is set, register liveness information in basic block
  144.   //  live-in lists and machine instruction operands (e.g. implicit defs) is
  145.   //  accurate, kill flags are conservatively accurate (kill flag correctly
  146.   //  indicates the last use of a register, an operand without kill flag may or
  147.   //  may not be the last use of a register). This means it can be used to
  148.   //  change the code in ways that affect the values in registers, for example
  149.   //  by the register scavenger.
  150.   //  When this property is cleared at a very late time, liveness is no longer
  151.   //  reliable.
  152.   // NoVRegs: The machine function does not use any virtual registers.
  153.   // Legalized: In GlobalISel: the MachineLegalizer ran and all pre-isel generic
  154.   //  instructions have been legalized; i.e., all instructions are now one of:
  155.   //   - generic and always legal (e.g., COPY)
  156.   //   - target-specific
  157.   //   - legal pre-isel generic instructions.
  158.   // RegBankSelected: In GlobalISel: the RegBankSelect pass ran and all generic
  159.   //  virtual registers have been assigned to a register bank.
  160.   // Selected: In GlobalISel: the InstructionSelect pass ran and all pre-isel
  161.   //  generic instructions have been eliminated; i.e., all instructions are now
  162.   //  target-specific or non-pre-isel generic instructions (e.g., COPY).
  163.   //  Since only pre-isel generic instructions can have generic virtual register
  164.   //  operands, this also means that all generic virtual registers have been
  165.   //  constrained to virtual registers (assigned to register classes) and that
  166.   //  all sizes attached to them have been eliminated.
  167.   // TiedOpsRewritten: The twoaddressinstruction pass will set this flag, it
  168.   //  means that tied-def have been rewritten to meet the RegConstraint.
  169.   // FailsVerification: Means that the function is not expected to pass machine
  170.   //  verification. This can be set by passes that introduce known problems that
  171.   //  have not been fixed yet.
  172.   // TracksDebugUserValues: Without this property enabled, debug instructions
  173.   // such as DBG_VALUE are allowed to reference virtual registers even if those
  174.   // registers do not have a definition. With the property enabled virtual
  175.   // registers must only be used if they have a definition. This property
  176.   // allows earlier passes in the pipeline to skip updates of `DBG_VALUE`
  177.   // instructions to save compile time.
  178.   enum class Property : unsigned {
  179.     IsSSA,
  180.     NoPHIs,
  181.     TracksLiveness,
  182.     NoVRegs,
  183.     FailedISel,
  184.     Legalized,
  185.     RegBankSelected,
  186.     Selected,
  187.     TiedOpsRewritten,
  188.     FailsVerification,
  189.     TracksDebugUserValues,
  190.     LastProperty = TracksDebugUserValues,
  191.   };
  192.  
  193.   bool hasProperty(Property P) const {
  194.     return Properties[static_cast<unsigned>(P)];
  195.   }
  196.  
  197.   MachineFunctionProperties &set(Property P) {
  198.     Properties.set(static_cast<unsigned>(P));
  199.     return *this;
  200.   }
  201.  
  202.   MachineFunctionProperties &reset(Property P) {
  203.     Properties.reset(static_cast<unsigned>(P));
  204.     return *this;
  205.   }
  206.  
  207.   /// Reset all the properties.
  208.   MachineFunctionProperties &reset() {
  209.     Properties.reset();
  210.     return *this;
  211.   }
  212.  
  213.   MachineFunctionProperties &set(const MachineFunctionProperties &MFP) {
  214.     Properties |= MFP.Properties;
  215.     return *this;
  216.   }
  217.  
  218.   MachineFunctionProperties &reset(const MachineFunctionProperties &MFP) {
  219.     Properties.reset(MFP.Properties);
  220.     return *this;
  221.   }
  222.  
  223.   // Returns true if all properties set in V (i.e. required by a pass) are set
  224.   // in this.
  225.   bool verifyRequiredProperties(const MachineFunctionProperties &V) const {
  226.     return !V.Properties.test(Properties);
  227.   }
  228.  
  229.   /// Print the MachineFunctionProperties in human-readable form.
  230.   void print(raw_ostream &OS) const;
  231.  
  232. private:
  233.   BitVector Properties =
  234.       BitVector(static_cast<unsigned>(Property::LastProperty)+1);
  235. };
  236.  
  237. struct SEHHandler {
  238.   /// Filter or finally function. Null indicates a catch-all.
  239.   const Function *FilterOrFinally;
  240.  
  241.   /// Address of block to recover at. Null for a finally handler.
  242.   const BlockAddress *RecoverBA;
  243. };
  244.  
  245. /// This structure is used to retain landing pad info for the current function.
  246. struct LandingPadInfo {
  247.   MachineBasicBlock *LandingPadBlock;      // Landing pad block.
  248.   SmallVector<MCSymbol *, 1> BeginLabels;  // Labels prior to invoke.
  249.   SmallVector<MCSymbol *, 1> EndLabels;    // Labels after invoke.
  250.   SmallVector<SEHHandler, 1> SEHHandlers;  // SEH handlers active at this lpad.
  251.   MCSymbol *LandingPadLabel = nullptr;     // Label at beginning of landing pad.
  252.   std::vector<int> TypeIds;                // List of type ids (filters negative).
  253.  
  254.   explicit LandingPadInfo(MachineBasicBlock *MBB)
  255.       : LandingPadBlock(MBB) {}
  256. };
  257.  
  258. class LLVM_EXTERNAL_VISIBILITY MachineFunction {
  259.   Function &F;
  260.   const LLVMTargetMachine &Target;
  261.   const TargetSubtargetInfo *STI;
  262.   MCContext &Ctx;
  263.   MachineModuleInfo &MMI;
  264.  
  265.   // RegInfo - Information about each register in use in the function.
  266.   MachineRegisterInfo *RegInfo;
  267.  
  268.   // Used to keep track of target-specific per-machine function information for
  269.   // the target implementation.
  270.   MachineFunctionInfo *MFInfo;
  271.  
  272.   // Keep track of objects allocated on the stack.
  273.   MachineFrameInfo *FrameInfo;
  274.  
  275.   // Keep track of constants which are spilled to memory
  276.   MachineConstantPool *ConstantPool;
  277.  
  278.   // Keep track of jump tables for switch instructions
  279.   MachineJumpTableInfo *JumpTableInfo;
  280.  
  281.   // Keep track of the function section.
  282.   MCSection *Section = nullptr;
  283.  
  284.   // Catchpad unwind destination info for wasm EH.
  285.   // Keeps track of Wasm exception handling related data. This will be null for
  286.   // functions that aren't using a wasm EH personality.
  287.   WasmEHFuncInfo *WasmEHInfo = nullptr;
  288.  
  289.   // Keeps track of Windows exception handling related data. This will be null
  290.   // for functions that aren't using a funclet-based EH personality.
  291.   WinEHFuncInfo *WinEHInfo = nullptr;
  292.  
  293.   // Function-level unique numbering for MachineBasicBlocks.  When a
  294.   // MachineBasicBlock is inserted into a MachineFunction is it automatically
  295.   // numbered and this vector keeps track of the mapping from ID's to MBB's.
  296.   std::vector<MachineBasicBlock*> MBBNumbering;
  297.  
  298.   // Pool-allocate MachineFunction-lifetime and IR objects.
  299.   BumpPtrAllocator Allocator;
  300.  
  301.   // Allocation management for instructions in function.
  302.   Recycler<MachineInstr> InstructionRecycler;
  303.  
  304.   // Allocation management for operand arrays on instructions.
  305.   ArrayRecycler<MachineOperand> OperandRecycler;
  306.  
  307.   // Allocation management for basic blocks in function.
  308.   Recycler<MachineBasicBlock> BasicBlockRecycler;
  309.  
  310.   // List of machine basic blocks in function
  311.   using BasicBlockListType = ilist<MachineBasicBlock>;
  312.   BasicBlockListType BasicBlocks;
  313.  
  314.   /// FunctionNumber - This provides a unique ID for each function emitted in
  315.   /// this translation unit.
  316.   ///
  317.   unsigned FunctionNumber;
  318.  
  319.   /// Alignment - The alignment of the function.
  320.   Align Alignment;
  321.  
  322.   /// ExposesReturnsTwice - True if the function calls setjmp or related
  323.   /// functions with attribute "returns twice", but doesn't have
  324.   /// the attribute itself.
  325.   /// This is used to limit optimizations which cannot reason
  326.   /// about the control flow of such functions.
  327.   bool ExposesReturnsTwice = false;
  328.  
  329.   /// True if the function includes any inline assembly.
  330.   bool HasInlineAsm = false;
  331.  
  332.   /// True if any WinCFI instruction have been emitted in this function.
  333.   bool HasWinCFI = false;
  334.  
  335.   /// Current high-level properties of the IR of the function (e.g. is in SSA
  336.   /// form or whether registers have been allocated)
  337.   MachineFunctionProperties Properties;
  338.  
  339.   // Allocation management for pseudo source values.
  340.   std::unique_ptr<PseudoSourceValueManager> PSVManager;
  341.  
  342.   /// List of moves done by a function's prolog.  Used to construct frame maps
  343.   /// by debug and exception handling consumers.
  344.   std::vector<MCCFIInstruction> FrameInstructions;
  345.  
  346.   /// List of basic blocks immediately following calls to _setjmp. Used to
  347.   /// construct a table of valid longjmp targets for Windows Control Flow Guard.
  348.   std::vector<MCSymbol *> LongjmpTargets;
  349.  
  350.   /// List of basic blocks that are the target of catchrets. Used to construct
  351.   /// a table of valid targets for Windows EHCont Guard.
  352.   std::vector<MCSymbol *> CatchretTargets;
  353.  
  354.   /// \name Exception Handling
  355.   /// \{
  356.  
  357.   /// List of LandingPadInfo describing the landing pad information.
  358.   std::vector<LandingPadInfo> LandingPads;
  359.  
  360.   /// Map a landing pad's EH symbol to the call site indexes.
  361.   DenseMap<MCSymbol*, SmallVector<unsigned, 4>> LPadToCallSiteMap;
  362.  
  363.   /// Map a landing pad to its index.
  364.   DenseMap<const MachineBasicBlock *, unsigned> WasmLPadToIndexMap;
  365.  
  366.   /// Map of invoke call site index values to associated begin EH_LABEL.
  367.   DenseMap<MCSymbol*, unsigned> CallSiteMap;
  368.  
  369.   /// CodeView label annotations.
  370.   std::vector<std::pair<MCSymbol *, MDNode *>> CodeViewAnnotations;
  371.  
  372.   bool CallsEHReturn = false;
  373.   bool CallsUnwindInit = false;
  374.   bool HasEHCatchret = false;
  375.   bool HasEHScopes = false;
  376.   bool HasEHFunclets = false;
  377.  
  378.   /// BBID to assign to the next basic block of this function.
  379.   unsigned NextBBID = 0;
  380.  
  381.   /// Section Type for basic blocks, only relevant with basic block sections.
  382.   BasicBlockSection BBSectionsType = BasicBlockSection::None;
  383.  
  384.   /// List of C++ TypeInfo used.
  385.   std::vector<const GlobalValue *> TypeInfos;
  386.  
  387.   /// List of typeids encoding filters used.
  388.   std::vector<unsigned> FilterIds;
  389.  
  390.   /// List of the indices in FilterIds corresponding to filter terminators.
  391.   std::vector<unsigned> FilterEnds;
  392.  
  393.   EHPersonality PersonalityTypeCache = EHPersonality::Unknown;
  394.  
  395.   /// \}
  396.  
  397.   /// Clear all the members of this MachineFunction, but the ones used
  398.   /// to initialize again the MachineFunction.
  399.   /// More specifically, this deallocates all the dynamically allocated
  400.   /// objects and get rid of all the XXXInfo data structure, but keep
  401.   /// unchanged the references to Fn, Target, MMI, and FunctionNumber.
  402.   void clear();
  403.   /// Allocate and initialize the different members.
  404.   /// In particular, the XXXInfo data structure.
  405.   /// \pre Fn, Target, MMI, and FunctionNumber are properly set.
  406.   void init();
  407.  
  408. public:
  409.   struct VariableDbgInfo {
  410.     const DILocalVariable *Var;
  411.     const DIExpression *Expr;
  412.     // The Slot can be negative for fixed stack objects.
  413.     int Slot;
  414.     const DILocation *Loc;
  415.  
  416.     VariableDbgInfo(const DILocalVariable *Var, const DIExpression *Expr,
  417.                     int Slot, const DILocation *Loc)
  418.         : Var(Var), Expr(Expr), Slot(Slot), Loc(Loc) {}
  419.   };
  420.  
  421.   class Delegate {
  422.     virtual void anchor();
  423.  
  424.   public:
  425.     virtual ~Delegate() = default;
  426.     /// Callback after an insertion. This should not modify the MI directly.
  427.     virtual void MF_HandleInsertion(MachineInstr &MI) = 0;
  428.     /// Callback before a removal. This should not modify the MI directly.
  429.     virtual void MF_HandleRemoval(MachineInstr &MI) = 0;
  430.   };
  431.  
  432.   /// Structure used to represent pair of argument number after call lowering
  433.   /// and register used to transfer that argument.
  434.   /// For now we support only cases when argument is transferred through one
  435.   /// register.
  436.   struct ArgRegPair {
  437.     Register Reg;
  438.     uint16_t ArgNo;
  439.     ArgRegPair(Register R, unsigned Arg) : Reg(R), ArgNo(Arg) {
  440.       assert(Arg < (1 << 16) && "Arg out of range");
  441.     }
  442.   };
  443.   /// Vector of call argument and its forwarding register.
  444.   using CallSiteInfo = SmallVector<ArgRegPair, 1>;
  445.   using CallSiteInfoImpl = SmallVectorImpl<ArgRegPair>;
  446.  
  447. private:
  448.   Delegate *TheDelegate = nullptr;
  449.   GISelChangeObserver *Observer = nullptr;
  450.  
  451.   using CallSiteInfoMap = DenseMap<const MachineInstr *, CallSiteInfo>;
  452.   /// Map a call instruction to call site arguments forwarding info.
  453.   CallSiteInfoMap CallSitesInfo;
  454.  
  455.   /// A helper function that returns call site info for a give call
  456.   /// instruction if debug entry value support is enabled.
  457.   CallSiteInfoMap::iterator getCallSiteInfo(const MachineInstr *MI);
  458.  
  459.   // Callbacks for insertion and removal.
  460.   void handleInsertion(MachineInstr &MI);
  461.   void handleRemoval(MachineInstr &MI);
  462.   friend struct ilist_traits<MachineInstr>;
  463.  
  464. public:
  465.   using VariableDbgInfoMapTy = SmallVector<VariableDbgInfo, 4>;
  466.   VariableDbgInfoMapTy VariableDbgInfos;
  467.  
  468.   /// A count of how many instructions in the function have had numbers
  469.   /// assigned to them. Used for debug value tracking, to determine the
  470.   /// next instruction number.
  471.   unsigned DebugInstrNumberingCount = 0;
  472.  
  473.   /// Set value of DebugInstrNumberingCount field. Avoid using this unless
  474.   /// you're deserializing this data.
  475.   void setDebugInstrNumberingCount(unsigned Num);
  476.  
  477.   /// Pair of instruction number and operand number.
  478.   using DebugInstrOperandPair = std::pair<unsigned, unsigned>;
  479.  
  480.   /// Replacement definition for a debug instruction reference. Made up of a
  481.   /// source instruction / operand pair, destination pair, and a qualifying
  482.   /// subregister indicating what bits in the operand make up the substitution.
  483.   // For example, a debug user
  484.   /// of %1:
  485.   ///    %0:gr32 = someinst, debug-instr-number 1
  486.   ///    %1:gr16 = %0.some_16_bit_subreg, debug-instr-number 2
  487.   /// Would receive the substitution {{2, 0}, {1, 0}, $subreg}, where $subreg is
  488.   /// the subregister number for some_16_bit_subreg.
  489.   class DebugSubstitution {
  490.   public:
  491.     DebugInstrOperandPair Src;  ///< Source instruction / operand pair.
  492.     DebugInstrOperandPair Dest; ///< Replacement instruction / operand pair.
  493.     unsigned Subreg;            ///< Qualifier for which part of Dest is read.
  494.  
  495.     DebugSubstitution(const DebugInstrOperandPair &Src,
  496.                       const DebugInstrOperandPair &Dest, unsigned Subreg)
  497.         : Src(Src), Dest(Dest), Subreg(Subreg) {}
  498.  
  499.     /// Order only by source instruction / operand pair: there should never
  500.     /// be duplicate entries for the same source in any collection.
  501.     bool operator<(const DebugSubstitution &Other) const {
  502.       return Src < Other.Src;
  503.     }
  504.   };
  505.  
  506.   /// Debug value substitutions: a collection of DebugSubstitution objects,
  507.   /// recording changes in where a value is defined. For example, when one
  508.   /// instruction is substituted for another. Keeping a record allows recovery
  509.   /// of variable locations after compilation finishes.
  510.   SmallVector<DebugSubstitution, 8> DebugValueSubstitutions;
  511.  
  512.   /// Location of a PHI instruction that is also a debug-info variable value,
  513.   /// for the duration of register allocation. Loaded by the PHI-elimination
  514.   /// pass, and emitted as DBG_PHI instructions during VirtRegRewriter, with
  515.   /// maintenance applied by intermediate passes that edit registers (such as
  516.   /// coalescing and the allocator passes).
  517.   class DebugPHIRegallocPos {
  518.   public:
  519.     MachineBasicBlock *MBB; ///< Block where this PHI was originally located.
  520.     Register Reg;           ///< VReg where the control-flow-merge happens.
  521.     unsigned SubReg;        ///< Optional subreg qualifier within Reg.
  522.     DebugPHIRegallocPos(MachineBasicBlock *MBB, Register Reg, unsigned SubReg)
  523.         : MBB(MBB), Reg(Reg), SubReg(SubReg) {}
  524.   };
  525.  
  526.   /// Map of debug instruction numbers to the position of their PHI instructions
  527.   /// during register allocation. See DebugPHIRegallocPos.
  528.   DenseMap<unsigned, DebugPHIRegallocPos> DebugPHIPositions;
  529.  
  530.   /// Flag for whether this function contains DBG_VALUEs (false) or
  531.   /// DBG_INSTR_REF (true).
  532.   bool UseDebugInstrRef = false;
  533.  
  534.   /// Create a substitution between one <instr,operand> value to a different,
  535.   /// new value.
  536.   void makeDebugValueSubstitution(DebugInstrOperandPair, DebugInstrOperandPair,
  537.                                   unsigned SubReg = 0);
  538.  
  539.   /// Create substitutions for any tracked values in \p Old, to point at
  540.   /// \p New. Needed when we re-create an instruction during optimization,
  541.   /// which has the same signature (i.e., def operands in the same place) but
  542.   /// a modified instruction type, flags, or otherwise. An example: X86 moves
  543.   /// are sometimes transformed into equivalent LEAs.
  544.   /// If the two instructions are not the same opcode, limit which operands to
  545.   /// examine for substitutions to the first N operands by setting
  546.   /// \p MaxOperand.
  547.   void substituteDebugValuesForInst(const MachineInstr &Old, MachineInstr &New,
  548.                                     unsigned MaxOperand = UINT_MAX);
  549.  
  550.   /// Find the underlying  defining instruction / operand for a COPY instruction
  551.   /// while in SSA form. Copies do not actually define values -- they move them
  552.   /// between registers. Labelling a COPY-like instruction with an instruction
  553.   /// number is to be avoided as it makes value numbers non-unique later in
  554.   /// compilation. This method follows the definition chain for any sequence of
  555.   /// COPY-like instructions to find whatever non-COPY-like instruction defines
  556.   /// the copied value; or for parameters, creates a DBG_PHI on entry.
  557.   /// May insert instructions into the entry block!
  558.   /// \p MI The copy-like instruction to salvage.
  559.   /// \p DbgPHICache A container to cache already-solved COPYs.
  560.   /// \returns An instruction/operand pair identifying the defining value.
  561.   DebugInstrOperandPair
  562.   salvageCopySSA(MachineInstr &MI,
  563.                  DenseMap<Register, DebugInstrOperandPair> &DbgPHICache);
  564.  
  565.   DebugInstrOperandPair salvageCopySSAImpl(MachineInstr &MI);
  566.  
  567.   /// Finalise any partially emitted debug instructions. These are DBG_INSTR_REF
  568.   /// instructions where we only knew the vreg of the value they use, not the
  569.   /// instruction that defines that vreg. Once isel finishes, we should have
  570.   /// enough information for every DBG_INSTR_REF to point at an instruction
  571.   /// (or DBG_PHI).
  572.   void finalizeDebugInstrRefs();
  573.  
  574.   /// Determine whether, in the current machine configuration, we should use
  575.   /// instruction referencing or not.
  576.   bool shouldUseDebugInstrRef() const;
  577.  
  578.   /// Returns true if the function's variable locations are tracked with
  579.   /// instruction referencing.
  580.   bool useDebugInstrRef() const;
  581.  
  582.   /// Set whether this function will use instruction referencing or not.
  583.   void setUseDebugInstrRef(bool UseInstrRef);
  584.  
  585.   /// A reserved operand number representing the instructions memory operand,
  586.   /// for instructions that have a stack spill fused into them.
  587.   const static unsigned int DebugOperandMemNumber;
  588.  
  589.   MachineFunction(Function &F, const LLVMTargetMachine &Target,
  590.                   const TargetSubtargetInfo &STI, unsigned FunctionNum,
  591.                   MachineModuleInfo &MMI);
  592.   MachineFunction(const MachineFunction &) = delete;
  593.   MachineFunction &operator=(const MachineFunction &) = delete;
  594.   ~MachineFunction();
  595.  
  596.   /// Reset the instance as if it was just created.
  597.   void reset() {
  598.     clear();
  599.     init();
  600.   }
  601.  
  602.   /// Reset the currently registered delegate - otherwise assert.
  603.   void resetDelegate(Delegate *delegate) {
  604.     assert(TheDelegate == delegate &&
  605.            "Only the current delegate can perform reset!");
  606.     TheDelegate = nullptr;
  607.   }
  608.  
  609.   /// Set the delegate. resetDelegate must be called before attempting
  610.   /// to set.
  611.   void setDelegate(Delegate *delegate) {
  612.     assert(delegate && !TheDelegate &&
  613.            "Attempted to set delegate to null, or to change it without "
  614.            "first resetting it!");
  615.  
  616.     TheDelegate = delegate;
  617.   }
  618.  
  619.   void setObserver(GISelChangeObserver *O) { Observer = O; }
  620.  
  621.   GISelChangeObserver *getObserver() const { return Observer; }
  622.  
  623.   MachineModuleInfo &getMMI() const { return MMI; }
  624.   MCContext &getContext() const { return Ctx; }
  625.  
  626.   /// Returns the Section this function belongs to.
  627.   MCSection *getSection() const { return Section; }
  628.  
  629.   /// Indicates the Section this function belongs to.
  630.   void setSection(MCSection *S) { Section = S; }
  631.  
  632.   PseudoSourceValueManager &getPSVManager() const { return *PSVManager; }
  633.  
  634.   /// Return the DataLayout attached to the Module associated to this MF.
  635.   const DataLayout &getDataLayout() const;
  636.  
  637.   /// Return the LLVM function that this machine code represents
  638.   Function &getFunction() { return F; }
  639.  
  640.   /// Return the LLVM function that this machine code represents
  641.   const Function &getFunction() const { return F; }
  642.  
  643.   /// getName - Return the name of the corresponding LLVM function.
  644.   StringRef getName() const;
  645.  
  646.   /// getFunctionNumber - Return a unique ID for the current function.
  647.   unsigned getFunctionNumber() const { return FunctionNumber; }
  648.  
  649.   /// Returns true if this function has basic block sections enabled.
  650.   bool hasBBSections() const {
  651.     return (BBSectionsType == BasicBlockSection::All ||
  652.             BBSectionsType == BasicBlockSection::List ||
  653.             BBSectionsType == BasicBlockSection::Preset);
  654.   }
  655.  
  656.   /// Returns true if basic block labels are to be generated for this function.
  657.   bool hasBBLabels() const {
  658.     return BBSectionsType == BasicBlockSection::Labels;
  659.   }
  660.  
  661.   void setBBSectionsType(BasicBlockSection V) { BBSectionsType = V; }
  662.  
  663.   /// Assign IsBeginSection IsEndSection fields for basic blocks in this
  664.   /// function.
  665.   void assignBeginEndSections();
  666.  
  667.   /// getTarget - Return the target machine this machine code is compiled with
  668.   const LLVMTargetMachine &getTarget() const { return Target; }
  669.  
  670.   /// getSubtarget - Return the subtarget for which this machine code is being
  671.   /// compiled.
  672.   const TargetSubtargetInfo &getSubtarget() const { return *STI; }
  673.  
  674.   /// getSubtarget - This method returns a pointer to the specified type of
  675.   /// TargetSubtargetInfo.  In debug builds, it verifies that the object being
  676.   /// returned is of the correct type.
  677.   template<typename STC> const STC &getSubtarget() const {
  678.     return *static_cast<const STC *>(STI);
  679.   }
  680.  
  681.   /// getRegInfo - Return information about the registers currently in use.
  682.   MachineRegisterInfo &getRegInfo() { return *RegInfo; }
  683.   const MachineRegisterInfo &getRegInfo() const { return *RegInfo; }
  684.  
  685.   /// getFrameInfo - Return the frame info object for the current function.
  686.   /// This object contains information about objects allocated on the stack
  687.   /// frame of the current function in an abstract way.
  688.   MachineFrameInfo &getFrameInfo() { return *FrameInfo; }
  689.   const MachineFrameInfo &getFrameInfo() const { return *FrameInfo; }
  690.  
  691.   /// getJumpTableInfo - Return the jump table info object for the current
  692.   /// function.  This object contains information about jump tables in the
  693.   /// current function.  If the current function has no jump tables, this will
  694.   /// return null.
  695.   const MachineJumpTableInfo *getJumpTableInfo() const { return JumpTableInfo; }
  696.   MachineJumpTableInfo *getJumpTableInfo() { return JumpTableInfo; }
  697.  
  698.   /// getOrCreateJumpTableInfo - Get the JumpTableInfo for this function, if it
  699.   /// does already exist, allocate one.
  700.   MachineJumpTableInfo *getOrCreateJumpTableInfo(unsigned JTEntryKind);
  701.  
  702.   /// getConstantPool - Return the constant pool object for the current
  703.   /// function.
  704.   MachineConstantPool *getConstantPool() { return ConstantPool; }
  705.   const MachineConstantPool *getConstantPool() const { return ConstantPool; }
  706.  
  707.   /// getWasmEHFuncInfo - Return information about how the current function uses
  708.   /// Wasm exception handling. Returns null for functions that don't use wasm
  709.   /// exception handling.
  710.   const WasmEHFuncInfo *getWasmEHFuncInfo() const { return WasmEHInfo; }
  711.   WasmEHFuncInfo *getWasmEHFuncInfo() { return WasmEHInfo; }
  712.  
  713.   /// getWinEHFuncInfo - Return information about how the current function uses
  714.   /// Windows exception handling. Returns null for functions that don't use
  715.   /// funclets for exception handling.
  716.   const WinEHFuncInfo *getWinEHFuncInfo() const { return WinEHInfo; }
  717.   WinEHFuncInfo *getWinEHFuncInfo() { return WinEHInfo; }
  718.  
  719.   /// getAlignment - Return the alignment of the function.
  720.   Align getAlignment() const { return Alignment; }
  721.  
  722.   /// setAlignment - Set the alignment of the function.
  723.   void setAlignment(Align A) { Alignment = A; }
  724.  
  725.   /// ensureAlignment - Make sure the function is at least A bytes aligned.
  726.   void ensureAlignment(Align A) {
  727.     if (Alignment < A)
  728.       Alignment = A;
  729.   }
  730.  
  731.   /// exposesReturnsTwice - Returns true if the function calls setjmp or
  732.   /// any other similar functions with attribute "returns twice" without
  733.   /// having the attribute itself.
  734.   bool exposesReturnsTwice() const {
  735.     return ExposesReturnsTwice;
  736.   }
  737.  
  738.   /// setCallsSetJmp - Set a flag that indicates if there's a call to
  739.   /// a "returns twice" function.
  740.   void setExposesReturnsTwice(bool B) {
  741.     ExposesReturnsTwice = B;
  742.   }
  743.  
  744.   /// Returns true if the function contains any inline assembly.
  745.   bool hasInlineAsm() const {
  746.     return HasInlineAsm;
  747.   }
  748.  
  749.   /// Set a flag that indicates that the function contains inline assembly.
  750.   void setHasInlineAsm(bool B) {
  751.     HasInlineAsm = B;
  752.   }
  753.  
  754.   bool hasWinCFI() const {
  755.     return HasWinCFI;
  756.   }
  757.   void setHasWinCFI(bool v) { HasWinCFI = v; }
  758.  
  759.   /// True if this function needs frame moves for debug or exceptions.
  760.   bool needsFrameMoves() const;
  761.  
  762.   /// Get the function properties
  763.   const MachineFunctionProperties &getProperties() const { return Properties; }
  764.   MachineFunctionProperties &getProperties() { return Properties; }
  765.  
  766.   /// getInfo - Keep track of various per-function pieces of information for
  767.   /// backends that would like to do so.
  768.   ///
  769.   template<typename Ty>
  770.   Ty *getInfo() {
  771.     return static_cast<Ty*>(MFInfo);
  772.   }
  773.  
  774.   template<typename Ty>
  775.   const Ty *getInfo() const {
  776.     return static_cast<const Ty *>(MFInfo);
  777.   }
  778.  
  779.   template <typename Ty> Ty *cloneInfo(const Ty &Old) {
  780.     assert(!MFInfo);
  781.     MFInfo = Ty::template create<Ty>(Allocator, Old);
  782.     return static_cast<Ty *>(MFInfo);
  783.   }
  784.  
  785.   /// Initialize the target specific MachineFunctionInfo
  786.   void initTargetMachineFunctionInfo(const TargetSubtargetInfo &STI);
  787.  
  788.   MachineFunctionInfo *cloneInfoFrom(
  789.       const MachineFunction &OrigMF,
  790.       const DenseMap<MachineBasicBlock *, MachineBasicBlock *> &Src2DstMBB) {
  791.     assert(!MFInfo && "new function already has MachineFunctionInfo");
  792.     if (!OrigMF.MFInfo)
  793.       return nullptr;
  794.     return OrigMF.MFInfo->clone(Allocator, *this, Src2DstMBB);
  795.   }
  796.  
  797.   /// Returns the denormal handling type for the default rounding mode of the
  798.   /// function.
  799.   DenormalMode getDenormalMode(const fltSemantics &FPType) const;
  800.  
  801.   /// getBlockNumbered - MachineBasicBlocks are automatically numbered when they
  802.   /// are inserted into the machine function.  The block number for a machine
  803.   /// basic block can be found by using the MBB::getNumber method, this method
  804.   /// provides the inverse mapping.
  805.   MachineBasicBlock *getBlockNumbered(unsigned N) const {
  806.     assert(N < MBBNumbering.size() && "Illegal block number");
  807.     assert(MBBNumbering[N] && "Block was removed from the machine function!");
  808.     return MBBNumbering[N];
  809.   }
  810.  
  811.   /// Should we be emitting segmented stack stuff for the function
  812.   bool shouldSplitStack() const;
  813.  
  814.   /// getNumBlockIDs - Return the number of MBB ID's allocated.
  815.   unsigned getNumBlockIDs() const { return (unsigned)MBBNumbering.size(); }
  816.  
  817.   /// RenumberBlocks - This discards all of the MachineBasicBlock numbers and
  818.   /// recomputes them.  This guarantees that the MBB numbers are sequential,
  819.   /// dense, and match the ordering of the blocks within the function.  If a
  820.   /// specific MachineBasicBlock is specified, only that block and those after
  821.   /// it are renumbered.
  822.   void RenumberBlocks(MachineBasicBlock *MBBFrom = nullptr);
  823.  
  824.   /// print - Print out the MachineFunction in a format suitable for debugging
  825.   /// to the specified stream.
  826.   void print(raw_ostream &OS, const SlotIndexes* = nullptr) const;
  827.  
  828.   /// viewCFG - This function is meant for use from the debugger.  You can just
  829.   /// say 'call F->viewCFG()' and a ghostview window should pop up from the
  830.   /// program, displaying the CFG of the current function with the code for each
  831.   /// basic block inside.  This depends on there being a 'dot' and 'gv' program
  832.   /// in your path.
  833.   void viewCFG() const;
  834.  
  835.   /// viewCFGOnly - This function is meant for use from the debugger.  It works
  836.   /// just like viewCFG, but it does not include the contents of basic blocks
  837.   /// into the nodes, just the label.  If you are only interested in the CFG
  838.   /// this can make the graph smaller.
  839.   ///
  840.   void viewCFGOnly() const;
  841.  
  842.   /// dump - Print the current MachineFunction to cerr, useful for debugger use.
  843.   void dump() const;
  844.  
  845.   /// Run the current MachineFunction through the machine code verifier, useful
  846.   /// for debugger use.
  847.   /// \returns true if no problems were found.
  848.   bool verify(Pass *p = nullptr, const char *Banner = nullptr,
  849.               bool AbortOnError = true) const;
  850.  
  851.   // Provide accessors for the MachineBasicBlock list...
  852.   using iterator = BasicBlockListType::iterator;
  853.   using const_iterator = BasicBlockListType::const_iterator;
  854.   using const_reverse_iterator = BasicBlockListType::const_reverse_iterator;
  855.   using reverse_iterator = BasicBlockListType::reverse_iterator;
  856.  
  857.   /// Support for MachineBasicBlock::getNextNode().
  858.   static BasicBlockListType MachineFunction::*
  859.   getSublistAccess(MachineBasicBlock *) {
  860.     return &MachineFunction::BasicBlocks;
  861.   }
  862.  
  863.   /// addLiveIn - Add the specified physical register as a live-in value and
  864.   /// create a corresponding virtual register for it.
  865.   Register addLiveIn(MCRegister PReg, const TargetRegisterClass *RC);
  866.  
  867.   //===--------------------------------------------------------------------===//
  868.   // BasicBlock accessor functions.
  869.   //
  870.   iterator                 begin()       { return BasicBlocks.begin(); }
  871.   const_iterator           begin() const { return BasicBlocks.begin(); }
  872.   iterator                 end  ()       { return BasicBlocks.end();   }
  873.   const_iterator           end  () const { return BasicBlocks.end();   }
  874.  
  875.   reverse_iterator        rbegin()       { return BasicBlocks.rbegin(); }
  876.   const_reverse_iterator  rbegin() const { return BasicBlocks.rbegin(); }
  877.   reverse_iterator        rend  ()       { return BasicBlocks.rend();   }
  878.   const_reverse_iterator  rend  () const { return BasicBlocks.rend();   }
  879.  
  880.   unsigned                  size() const { return (unsigned)BasicBlocks.size();}
  881.   bool                     empty() const { return BasicBlocks.empty(); }
  882.   const MachineBasicBlock &front() const { return BasicBlocks.front(); }
  883.         MachineBasicBlock &front()       { return BasicBlocks.front(); }
  884.   const MachineBasicBlock & back() const { return BasicBlocks.back(); }
  885.         MachineBasicBlock & back()       { return BasicBlocks.back(); }
  886.  
  887.   void push_back (MachineBasicBlock *MBB) { BasicBlocks.push_back (MBB); }
  888.   void push_front(MachineBasicBlock *MBB) { BasicBlocks.push_front(MBB); }
  889.   void insert(iterator MBBI, MachineBasicBlock *MBB) {
  890.     BasicBlocks.insert(MBBI, MBB);
  891.   }
  892.   void splice(iterator InsertPt, iterator MBBI) {
  893.     BasicBlocks.splice(InsertPt, BasicBlocks, MBBI);
  894.   }
  895.   void splice(iterator InsertPt, MachineBasicBlock *MBB) {
  896.     BasicBlocks.splice(InsertPt, BasicBlocks, MBB);
  897.   }
  898.   void splice(iterator InsertPt, iterator MBBI, iterator MBBE) {
  899.     BasicBlocks.splice(InsertPt, BasicBlocks, MBBI, MBBE);
  900.   }
  901.  
  902.   void remove(iterator MBBI) { BasicBlocks.remove(MBBI); }
  903.   void remove(MachineBasicBlock *MBBI) { BasicBlocks.remove(MBBI); }
  904.   void erase(iterator MBBI) { BasicBlocks.erase(MBBI); }
  905.   void erase(MachineBasicBlock *MBBI) { BasicBlocks.erase(MBBI); }
  906.  
  907.   template <typename Comp>
  908.   void sort(Comp comp) {
  909.     BasicBlocks.sort(comp);
  910.   }
  911.  
  912.   /// Return the number of \p MachineInstrs in this \p MachineFunction.
  913.   unsigned getInstructionCount() const {
  914.     unsigned InstrCount = 0;
  915.     for (const MachineBasicBlock &MBB : BasicBlocks)
  916.       InstrCount += MBB.size();
  917.     return InstrCount;
  918.   }
  919.  
  920.   //===--------------------------------------------------------------------===//
  921.   // Internal functions used to automatically number MachineBasicBlocks
  922.  
  923.   /// Adds the MBB to the internal numbering. Returns the unique number
  924.   /// assigned to the MBB.
  925.   unsigned addToMBBNumbering(MachineBasicBlock *MBB) {
  926.     MBBNumbering.push_back(MBB);
  927.     return (unsigned)MBBNumbering.size()-1;
  928.   }
  929.  
  930.   /// removeFromMBBNumbering - Remove the specific machine basic block from our
  931.   /// tracker, this is only really to be used by the MachineBasicBlock
  932.   /// implementation.
  933.   void removeFromMBBNumbering(unsigned N) {
  934.     assert(N < MBBNumbering.size() && "Illegal basic block #");
  935.     MBBNumbering[N] = nullptr;
  936.   }
  937.  
  938.   /// CreateMachineInstr - Allocate a new MachineInstr. Use this instead
  939.   /// of `new MachineInstr'.
  940.   MachineInstr *CreateMachineInstr(const MCInstrDesc &MCID, DebugLoc DL,
  941.                                    bool NoImplicit = false);
  942.  
  943.   /// Create a new MachineInstr which is a copy of \p Orig, identical in all
  944.   /// ways except the instruction has no parent, prev, or next. Bundling flags
  945.   /// are reset.
  946.   ///
  947.   /// Note: Clones a single instruction, not whole instruction bundles.
  948.   /// Does not perform target specific adjustments; consider using
  949.   /// TargetInstrInfo::duplicate() instead.
  950.   MachineInstr *CloneMachineInstr(const MachineInstr *Orig);
  951.  
  952.   /// Clones instruction or the whole instruction bundle \p Orig and insert
  953.   /// into \p MBB before \p InsertBefore.
  954.   ///
  955.   /// Note: Does not perform target specific adjustments; consider using
  956.   /// TargetInstrInfo::duplicate() intead.
  957.   MachineInstr &
  958.   cloneMachineInstrBundle(MachineBasicBlock &MBB,
  959.                           MachineBasicBlock::iterator InsertBefore,
  960.                           const MachineInstr &Orig);
  961.  
  962.   /// DeleteMachineInstr - Delete the given MachineInstr.
  963.   void deleteMachineInstr(MachineInstr *MI);
  964.  
  965.   /// CreateMachineBasicBlock - Allocate a new MachineBasicBlock. Use this
  966.   /// instead of `new MachineBasicBlock'.
  967.   MachineBasicBlock *CreateMachineBasicBlock(const BasicBlock *bb = nullptr);
  968.  
  969.   /// DeleteMachineBasicBlock - Delete the given MachineBasicBlock.
  970.   void deleteMachineBasicBlock(MachineBasicBlock *MBB);
  971.  
  972.   /// getMachineMemOperand - Allocate a new MachineMemOperand.
  973.   /// MachineMemOperands are owned by the MachineFunction and need not be
  974.   /// explicitly deallocated.
  975.   MachineMemOperand *getMachineMemOperand(
  976.       MachinePointerInfo PtrInfo, MachineMemOperand::Flags f, uint64_t s,
  977.       Align base_alignment, const AAMDNodes &AAInfo = AAMDNodes(),
  978.       const MDNode *Ranges = nullptr, SyncScope::ID SSID = SyncScope::System,
  979.       AtomicOrdering Ordering = AtomicOrdering::NotAtomic,
  980.       AtomicOrdering FailureOrdering = AtomicOrdering::NotAtomic);
  981.  
  982.   MachineMemOperand *getMachineMemOperand(
  983.       MachinePointerInfo PtrInfo, MachineMemOperand::Flags f, LLT MemTy,
  984.       Align base_alignment, const AAMDNodes &AAInfo = AAMDNodes(),
  985.       const MDNode *Ranges = nullptr, SyncScope::ID SSID = SyncScope::System,
  986.       AtomicOrdering Ordering = AtomicOrdering::NotAtomic,
  987.       AtomicOrdering FailureOrdering = AtomicOrdering::NotAtomic);
  988.  
  989.   /// getMachineMemOperand - Allocate a new MachineMemOperand by copying
  990.   /// an existing one, adjusting by an offset and using the given size.
  991.   /// MachineMemOperands are owned by the MachineFunction and need not be
  992.   /// explicitly deallocated.
  993.   MachineMemOperand *getMachineMemOperand(const MachineMemOperand *MMO,
  994.                                           int64_t Offset, LLT Ty);
  995.   MachineMemOperand *getMachineMemOperand(const MachineMemOperand *MMO,
  996.                                           int64_t Offset, uint64_t Size) {
  997.     return getMachineMemOperand(
  998.         MMO, Offset, Size == ~UINT64_C(0) ? LLT() : LLT::scalar(8 * Size));
  999.   }
  1000.  
  1001.   /// getMachineMemOperand - Allocate a new MachineMemOperand by copying
  1002.   /// an existing one, replacing only the MachinePointerInfo and size.
  1003.   /// MachineMemOperands are owned by the MachineFunction and need not be
  1004.   /// explicitly deallocated.
  1005.   MachineMemOperand *getMachineMemOperand(const MachineMemOperand *MMO,
  1006.                                           const MachinePointerInfo &PtrInfo,
  1007.                                           uint64_t Size);
  1008.   MachineMemOperand *getMachineMemOperand(const MachineMemOperand *MMO,
  1009.                                           const MachinePointerInfo &PtrInfo,
  1010.                                           LLT Ty);
  1011.  
  1012.   /// Allocate a new MachineMemOperand by copying an existing one,
  1013.   /// replacing only AliasAnalysis information. MachineMemOperands are owned
  1014.   /// by the MachineFunction and need not be explicitly deallocated.
  1015.   MachineMemOperand *getMachineMemOperand(const MachineMemOperand *MMO,
  1016.                                           const AAMDNodes &AAInfo);
  1017.  
  1018.   /// Allocate a new MachineMemOperand by copying an existing one,
  1019.   /// replacing the flags. MachineMemOperands are owned
  1020.   /// by the MachineFunction and need not be explicitly deallocated.
  1021.   MachineMemOperand *getMachineMemOperand(const MachineMemOperand *MMO,
  1022.                                           MachineMemOperand::Flags Flags);
  1023.  
  1024.   using OperandCapacity = ArrayRecycler<MachineOperand>::Capacity;
  1025.  
  1026.   /// Allocate an array of MachineOperands. This is only intended for use by
  1027.   /// internal MachineInstr functions.
  1028.   MachineOperand *allocateOperandArray(OperandCapacity Cap) {
  1029.     return OperandRecycler.allocate(Cap, Allocator);
  1030.   }
  1031.  
  1032.   /// Dellocate an array of MachineOperands and recycle the memory. This is
  1033.   /// only intended for use by internal MachineInstr functions.
  1034.   /// Cap must be the same capacity that was used to allocate the array.
  1035.   void deallocateOperandArray(OperandCapacity Cap, MachineOperand *Array) {
  1036.     OperandRecycler.deallocate(Cap, Array);
  1037.   }
  1038.  
  1039.   /// Allocate and initialize a register mask with @p NumRegister bits.
  1040.   uint32_t *allocateRegMask();
  1041.  
  1042.   ArrayRef<int> allocateShuffleMask(ArrayRef<int> Mask);
  1043.  
  1044.   /// Allocate and construct an extra info structure for a `MachineInstr`.
  1045.   ///
  1046.   /// This is allocated on the function's allocator and so lives the life of
  1047.   /// the function.
  1048.   MachineInstr::ExtraInfo *createMIExtraInfo(
  1049.       ArrayRef<MachineMemOperand *> MMOs, MCSymbol *PreInstrSymbol = nullptr,
  1050.       MCSymbol *PostInstrSymbol = nullptr, MDNode *HeapAllocMarker = nullptr,
  1051.       MDNode *PCSections = nullptr, uint32_t CFIType = 0);
  1052.  
  1053.   /// Allocate a string and populate it with the given external symbol name.
  1054.   const char *createExternalSymbolName(StringRef Name);
  1055.  
  1056.   //===--------------------------------------------------------------------===//
  1057.   // Label Manipulation.
  1058.  
  1059.   /// getJTISymbol - Return the MCSymbol for the specified non-empty jump table.
  1060.   /// If isLinkerPrivate is specified, an 'l' label is returned, otherwise a
  1061.   /// normal 'L' label is returned.
  1062.   MCSymbol *getJTISymbol(unsigned JTI, MCContext &Ctx,
  1063.                          bool isLinkerPrivate = false) const;
  1064.  
  1065.   /// getPICBaseSymbol - Return a function-local symbol to represent the PIC
  1066.   /// base.
  1067.   MCSymbol *getPICBaseSymbol() const;
  1068.  
  1069.   /// Returns a reference to a list of cfi instructions in the function's
  1070.   /// prologue.  Used to construct frame maps for debug and exception handling
  1071.   /// comsumers.
  1072.   const std::vector<MCCFIInstruction> &getFrameInstructions() const {
  1073.     return FrameInstructions;
  1074.   }
  1075.  
  1076.   [[nodiscard]] unsigned addFrameInst(const MCCFIInstruction &Inst);
  1077.  
  1078.   /// Returns a reference to a list of symbols immediately following calls to
  1079.   /// _setjmp in the function. Used to construct the longjmp target table used
  1080.   /// by Windows Control Flow Guard.
  1081.   const std::vector<MCSymbol *> &getLongjmpTargets() const {
  1082.     return LongjmpTargets;
  1083.   }
  1084.  
  1085.   /// Add the specified symbol to the list of valid longjmp targets for Windows
  1086.   /// Control Flow Guard.
  1087.   void addLongjmpTarget(MCSymbol *Target) { LongjmpTargets.push_back(Target); }
  1088.  
  1089.   /// Returns a reference to a list of symbols that we have catchrets.
  1090.   /// Used to construct the catchret target table used by Windows EHCont Guard.
  1091.   const std::vector<MCSymbol *> &getCatchretTargets() const {
  1092.     return CatchretTargets;
  1093.   }
  1094.  
  1095.   /// Add the specified symbol to the list of valid catchret targets for Windows
  1096.   /// EHCont Guard.
  1097.   void addCatchretTarget(MCSymbol *Target) {
  1098.     CatchretTargets.push_back(Target);
  1099.   }
  1100.  
  1101.   /// \name Exception Handling
  1102.   /// \{
  1103.  
  1104.   bool callsEHReturn() const { return CallsEHReturn; }
  1105.   void setCallsEHReturn(bool b) { CallsEHReturn = b; }
  1106.  
  1107.   bool callsUnwindInit() const { return CallsUnwindInit; }
  1108.   void setCallsUnwindInit(bool b) { CallsUnwindInit = b; }
  1109.  
  1110.   bool hasEHCatchret() const { return HasEHCatchret; }
  1111.   void setHasEHCatchret(bool V) { HasEHCatchret = V; }
  1112.  
  1113.   bool hasEHScopes() const { return HasEHScopes; }
  1114.   void setHasEHScopes(bool V) { HasEHScopes = V; }
  1115.  
  1116.   bool hasEHFunclets() const { return HasEHFunclets; }
  1117.   void setHasEHFunclets(bool V) { HasEHFunclets = V; }
  1118.  
  1119.   /// Find or create an LandingPadInfo for the specified MachineBasicBlock.
  1120.   LandingPadInfo &getOrCreateLandingPadInfo(MachineBasicBlock *LandingPad);
  1121.  
  1122.   /// Return a reference to the landing pad info for the current function.
  1123.   const std::vector<LandingPadInfo> &getLandingPads() const {
  1124.     return LandingPads;
  1125.   }
  1126.  
  1127.   /// Provide the begin and end labels of an invoke style call and associate it
  1128.   /// with a try landing pad block.
  1129.   void addInvoke(MachineBasicBlock *LandingPad,
  1130.                  MCSymbol *BeginLabel, MCSymbol *EndLabel);
  1131.  
  1132.   /// Add a new panding pad, and extract the exception handling information from
  1133.   /// the landingpad instruction. Returns the label ID for the landing pad
  1134.   /// entry.
  1135.   MCSymbol *addLandingPad(MachineBasicBlock *LandingPad);
  1136.  
  1137.   /// Return the type id for the specified typeinfo.  This is function wide.
  1138.   unsigned getTypeIDFor(const GlobalValue *TI);
  1139.  
  1140.   /// Return the id of the filter encoded by TyIds.  This is function wide.
  1141.   int getFilterIDFor(ArrayRef<unsigned> TyIds);
  1142.  
  1143.   /// Map the landing pad's EH symbol to the call site indexes.
  1144.   void setCallSiteLandingPad(MCSymbol *Sym, ArrayRef<unsigned> Sites);
  1145.  
  1146.   /// Return if there is any wasm exception handling.
  1147.   bool hasAnyWasmLandingPadIndex() const {
  1148.     return !WasmLPadToIndexMap.empty();
  1149.   }
  1150.  
  1151.   /// Map the landing pad to its index. Used for Wasm exception handling.
  1152.   void setWasmLandingPadIndex(const MachineBasicBlock *LPad, unsigned Index) {
  1153.     WasmLPadToIndexMap[LPad] = Index;
  1154.   }
  1155.  
  1156.   /// Returns true if the landing pad has an associate index in wasm EH.
  1157.   bool hasWasmLandingPadIndex(const MachineBasicBlock *LPad) const {
  1158.     return WasmLPadToIndexMap.count(LPad);
  1159.   }
  1160.  
  1161.   /// Get the index in wasm EH for a given landing pad.
  1162.   unsigned getWasmLandingPadIndex(const MachineBasicBlock *LPad) const {
  1163.     assert(hasWasmLandingPadIndex(LPad));
  1164.     return WasmLPadToIndexMap.lookup(LPad);
  1165.   }
  1166.  
  1167.   bool hasAnyCallSiteLandingPad() const {
  1168.     return !LPadToCallSiteMap.empty();
  1169.   }
  1170.  
  1171.   /// Get the call site indexes for a landing pad EH symbol.
  1172.   SmallVectorImpl<unsigned> &getCallSiteLandingPad(MCSymbol *Sym) {
  1173.     assert(hasCallSiteLandingPad(Sym) &&
  1174.            "missing call site number for landing pad!");
  1175.     return LPadToCallSiteMap[Sym];
  1176.   }
  1177.  
  1178.   /// Return true if the landing pad Eh symbol has an associated call site.
  1179.   bool hasCallSiteLandingPad(MCSymbol *Sym) {
  1180.     return !LPadToCallSiteMap[Sym].empty();
  1181.   }
  1182.  
  1183.   bool hasAnyCallSiteLabel() const {
  1184.     return !CallSiteMap.empty();
  1185.   }
  1186.  
  1187.   /// Map the begin label for a call site.
  1188.   void setCallSiteBeginLabel(MCSymbol *BeginLabel, unsigned Site) {
  1189.     CallSiteMap[BeginLabel] = Site;
  1190.   }
  1191.  
  1192.   /// Get the call site number for a begin label.
  1193.   unsigned getCallSiteBeginLabel(MCSymbol *BeginLabel) const {
  1194.     assert(hasCallSiteBeginLabel(BeginLabel) &&
  1195.            "Missing call site number for EH_LABEL!");
  1196.     return CallSiteMap.lookup(BeginLabel);
  1197.   }
  1198.  
  1199.   /// Return true if the begin label has a call site number associated with it.
  1200.   bool hasCallSiteBeginLabel(MCSymbol *BeginLabel) const {
  1201.     return CallSiteMap.count(BeginLabel);
  1202.   }
  1203.  
  1204.   /// Record annotations associated with a particular label.
  1205.   void addCodeViewAnnotation(MCSymbol *Label, MDNode *MD) {
  1206.     CodeViewAnnotations.push_back({Label, MD});
  1207.   }
  1208.  
  1209.   ArrayRef<std::pair<MCSymbol *, MDNode *>> getCodeViewAnnotations() const {
  1210.     return CodeViewAnnotations;
  1211.   }
  1212.  
  1213.   /// Return a reference to the C++ typeinfo for the current function.
  1214.   const std::vector<const GlobalValue *> &getTypeInfos() const {
  1215.     return TypeInfos;
  1216.   }
  1217.  
  1218.   /// Return a reference to the typeids encoding filters used in the current
  1219.   /// function.
  1220.   const std::vector<unsigned> &getFilterIds() const {
  1221.     return FilterIds;
  1222.   }
  1223.  
  1224.   /// \}
  1225.  
  1226.   /// Collect information used to emit debugging information of a variable.
  1227.   void setVariableDbgInfo(const DILocalVariable *Var, const DIExpression *Expr,
  1228.                           int Slot, const DILocation *Loc) {
  1229.     VariableDbgInfos.emplace_back(Var, Expr, Slot, Loc);
  1230.   }
  1231.  
  1232.   VariableDbgInfoMapTy &getVariableDbgInfo() { return VariableDbgInfos; }
  1233.   const VariableDbgInfoMapTy &getVariableDbgInfo() const {
  1234.     return VariableDbgInfos;
  1235.   }
  1236.  
  1237.   /// Start tracking the arguments passed to the call \p CallI.
  1238.   void addCallArgsForwardingRegs(const MachineInstr *CallI,
  1239.                                  CallSiteInfoImpl &&CallInfo) {
  1240.     assert(CallI->isCandidateForCallSiteEntry());
  1241.     bool Inserted =
  1242.         CallSitesInfo.try_emplace(CallI, std::move(CallInfo)).second;
  1243.     (void)Inserted;
  1244.     assert(Inserted && "Call site info not unique");
  1245.   }
  1246.  
  1247.   const CallSiteInfoMap &getCallSitesInfo() const {
  1248.     return CallSitesInfo;
  1249.   }
  1250.  
  1251.   /// Following functions update call site info. They should be called before
  1252.   /// removing, replacing or copying call instruction.
  1253.  
  1254.   /// Erase the call site info for \p MI. It is used to remove a call
  1255.   /// instruction from the instruction stream.
  1256.   void eraseCallSiteInfo(const MachineInstr *MI);
  1257.   /// Copy the call site info from \p Old to \ New. Its usage is when we are
  1258.   /// making a copy of the instruction that will be inserted at different point
  1259.   /// of the instruction stream.
  1260.   void copyCallSiteInfo(const MachineInstr *Old,
  1261.                         const MachineInstr *New);
  1262.  
  1263.   /// Move the call site info from \p Old to \New call site info. This function
  1264.   /// is used when we are replacing one call instruction with another one to
  1265.   /// the same callee.
  1266.   void moveCallSiteInfo(const MachineInstr *Old,
  1267.                         const MachineInstr *New);
  1268.  
  1269.   unsigned getNewDebugInstrNum() {
  1270.     return ++DebugInstrNumberingCount;
  1271.   }
  1272. };
  1273.  
  1274. //===--------------------------------------------------------------------===//
  1275. // GraphTraits specializations for function basic block graphs (CFGs)
  1276. //===--------------------------------------------------------------------===//
  1277.  
  1278. // Provide specializations of GraphTraits to be able to treat a
  1279. // machine function as a graph of machine basic blocks... these are
  1280. // the same as the machine basic block iterators, except that the root
  1281. // node is implicitly the first node of the function.
  1282. //
  1283. template <> struct GraphTraits<MachineFunction*> :
  1284.   public GraphTraits<MachineBasicBlock*> {
  1285.   static NodeRef getEntryNode(MachineFunction *F) { return &F->front(); }
  1286.  
  1287.   // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
  1288.   using nodes_iterator = pointer_iterator<MachineFunction::iterator>;
  1289.  
  1290.   static nodes_iterator nodes_begin(MachineFunction *F) {
  1291.     return nodes_iterator(F->begin());
  1292.   }
  1293.  
  1294.   static nodes_iterator nodes_end(MachineFunction *F) {
  1295.     return nodes_iterator(F->end());
  1296.   }
  1297.  
  1298.   static unsigned       size       (MachineFunction *F) { return F->size(); }
  1299. };
  1300. template <> struct GraphTraits<const MachineFunction*> :
  1301.   public GraphTraits<const MachineBasicBlock*> {
  1302.   static NodeRef getEntryNode(const MachineFunction *F) { return &F->front(); }
  1303.  
  1304.   // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
  1305.   using nodes_iterator = pointer_iterator<MachineFunction::const_iterator>;
  1306.  
  1307.   static nodes_iterator nodes_begin(const MachineFunction *F) {
  1308.     return nodes_iterator(F->begin());
  1309.   }
  1310.  
  1311.   static nodes_iterator nodes_end  (const MachineFunction *F) {
  1312.     return nodes_iterator(F->end());
  1313.   }
  1314.  
  1315.   static unsigned       size       (const MachineFunction *F)  {
  1316.     return F->size();
  1317.   }
  1318. };
  1319.  
  1320. // Provide specializations of GraphTraits to be able to treat a function as a
  1321. // graph of basic blocks... and to walk it in inverse order.  Inverse order for
  1322. // a function is considered to be when traversing the predecessor edges of a BB
  1323. // instead of the successor edges.
  1324. //
  1325. template <> struct GraphTraits<Inverse<MachineFunction*>> :
  1326.   public GraphTraits<Inverse<MachineBasicBlock*>> {
  1327.   static NodeRef getEntryNode(Inverse<MachineFunction *> G) {
  1328.     return &G.Graph->front();
  1329.   }
  1330. };
  1331. template <> struct GraphTraits<Inverse<const MachineFunction*>> :
  1332.   public GraphTraits<Inverse<const MachineBasicBlock*>> {
  1333.   static NodeRef getEntryNode(Inverse<const MachineFunction *> G) {
  1334.     return &G.Graph->front();
  1335.   }
  1336. };
  1337.  
  1338. class MachineFunctionAnalysisManager;
  1339. void verifyMachineFunction(MachineFunctionAnalysisManager *,
  1340.                            const std::string &Banner,
  1341.                            const MachineFunction &MF);
  1342.  
  1343. } // end namespace llvm
  1344.  
  1345. #endif // LLVM_CODEGEN_MACHINEFUNCTION_H
  1346.