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 //===-- CodeGen/MachineFrameInfo.h - Abstract Stack Frame Rep. --*- 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 file defines the MachineFrameInfo class.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_CODEGEN_MACHINEFRAMEINFO_H
 #define LLVM_CODEGEN_MACHINEFRAMEINFO_H
 
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/CodeGen/Register.h"
 #include "llvm/CodeGen/TargetFrameLowering.h"
 #include "llvm/Support/Alignment.h"
 #include <cassert>
 #include <vector>
 
 namespace llvm {
 class raw_ostream;
 class MachineFunction;
 class MachineBasicBlock;
 class BitVector;
 class AllocaInst;
 
 /// The CalleeSavedInfo class tracks the information need to locate where a
 /// callee saved register is in the current frame.
 /// Callee saved reg can also be saved to a different register rather than
 /// on the stack by setting DstReg instead of FrameIdx.
 class CalleeSavedInfo {
   Register Reg;
   union {
     int FrameIdx;
     unsigned DstReg;
   };
   /// Flag indicating whether the register is actually restored in the epilog.
   /// In most cases, if a register is saved, it is also restored. There are
   /// some situations, though, when this is not the case. For example, the
   /// LR register on ARM is usually saved, but on exit from the function its
   /// saved value may be loaded directly into PC. Since liveness tracking of
   /// physical registers treats callee-saved registers are live outside of
   /// the function, LR would be treated as live-on-exit, even though in these
   /// scenarios it is not. This flag is added to indicate that the saved
   /// register described by this object is not restored in the epilog.
   /// The long-term solution is to model the liveness of callee-saved registers
   /// by implicit uses on the return instructions, however, the required
   /// changes in the ARM backend would be quite extensive.
   bool Restored = true;
   /// Flag indicating whether the register is spilled to stack or another
   /// register.
   bool SpilledToReg = false;
 
 public:
   explicit CalleeSavedInfo(unsigned R, int FI = 0) : Reg(R), FrameIdx(FI) {}
 
   // Accessors.
   Register getReg()                        const { return Reg; }
   int getFrameIdx()                        const { return FrameIdx; }
   unsigned getDstReg()                     const { return DstReg; }
   void setFrameIdx(int FI) {
     FrameIdx = FI;
     SpilledToReg = false;
   }
   void setDstReg(Register SpillReg) {
     DstReg = SpillReg;
     SpilledToReg = true;
   }
   bool isRestored()                        const { return Restored; }
   void setRestored(bool R)                       { Restored = R; }
   bool isSpilledToReg()                    const { return SpilledToReg; }
 };
 
 /// The MachineFrameInfo class represents an abstract stack frame until
 /// prolog/epilog code is inserted.  This class is key to allowing stack frame
 /// representation optimizations, such as frame pointer elimination.  It also
 /// allows more mundane (but still important) optimizations, such as reordering
 /// of abstract objects on the stack frame.
 ///
 /// To support this, the class assigns unique integer identifiers to stack
 /// objects requested clients.  These identifiers are negative integers for
 /// fixed stack objects (such as arguments passed on the stack) or nonnegative
 /// for objects that may be reordered.  Instructions which refer to stack
 /// objects use a special MO_FrameIndex operand to represent these frame
 /// indexes.
 ///
 /// Because this class keeps track of all references to the stack frame, it
 /// knows when a variable sized object is allocated on the stack.  This is the
 /// sole condition which prevents frame pointer elimination, which is an
 /// important optimization on register-poor architectures.  Because original
 /// variable sized alloca's in the source program are the only source of
 /// variable sized stack objects, it is safe to decide whether there will be
 /// any variable sized objects before all stack objects are known (for
 /// example, register allocator spill code never needs variable sized
 /// objects).
 ///
 /// When prolog/epilog code emission is performed, the final stack frame is
 /// built and the machine instructions are modified to refer to the actual
 /// stack offsets of the object, eliminating all MO_FrameIndex operands from
 /// the program.
 ///
 /// Abstract Stack Frame Information
 class MachineFrameInfo {
 public:
   /// Stack Smashing Protection (SSP) rules require that vulnerable stack
   /// allocations are located close the stack protector.
   enum SSPLayoutKind {
     SSPLK_None,       ///< Did not trigger a stack protector.  No effect on data
                       ///< layout.
     SSPLK_LargeArray, ///< Array or nested array >= SSP-buffer-size.  Closest
                       ///< to the stack protector.
     SSPLK_SmallArray, ///< Array or nested array < SSP-buffer-size. 2nd closest
                       ///< to the stack protector.
     SSPLK_AddrOf      ///< The address of this allocation is exposed and
                       ///< triggered protection.  3rd closest to the protector.
   };
 
 private:
   // Represent a single object allocated on the stack.
   struct StackObject {
     // The offset of this object from the stack pointer on entry to
     // the function.  This field has no meaning for a variable sized element.
     int64_t SPOffset;
 
     // The size of this object on the stack. 0 means a variable sized object,
     // ~0ULL means a dead object.
     uint64_t Size;
 
     // The required alignment of this stack slot.
     Align Alignment;
 
     // If true, the value of the stack object is set before
     // entering the function and is not modified inside the function. By
     // default, fixed objects are immutable unless marked otherwise.
     bool isImmutable;
 
     // If true the stack object is used as spill slot. It
     // cannot alias any other memory objects.
     bool isSpillSlot;
 
     /// If true, this stack slot is used to spill a value (could be deopt
     /// and/or GC related) over a statepoint. We know that the address of the
     /// slot can't alias any LLVM IR value.  This is very similar to a Spill
     /// Slot, but is created by statepoint lowering is SelectionDAG, not the
     /// register allocator.
     bool isStatepointSpillSlot = false;
 
     /// Identifier for stack memory type analagous to address space. If this is
     /// non-0, the meaning is target defined. Offsets cannot be directly
     /// compared between objects with different stack IDs. The object may not
     /// necessarily reside in the same contiguous memory block as other stack
     /// objects. Objects with differing stack IDs should not be merged or
     /// replaced substituted for each other.
     //
     /// It is assumed a target uses consecutive, increasing stack IDs starting
     /// from 1.
     uint8_t StackID;
 
     /// If this stack object is originated from an Alloca instruction
     /// this value saves the original IR allocation. Can be NULL.
     const AllocaInst *Alloca;
 
     // If true, the object was mapped into the local frame
     // block and doesn't need additional handling for allocation beyond that.
     bool PreAllocated = false;
 
     // If true, an LLVM IR value might point to this object.
     // Normally, spill slots and fixed-offset objects don't alias IR-accessible
     // objects, but there are exceptions (on PowerPC, for example, some byval
     // arguments have ABI-prescribed offsets).
     bool isAliased;
 
     /// If true, the object has been zero-extended.
     bool isZExt = false;
 
     /// If true, the object has been sign-extended.
     bool isSExt = false;
 
     uint8_t SSPLayout = SSPLK_None;
 
     StackObject(uint64_t Size, Align Alignment, int64_t SPOffset,
                 bool IsImmutable, bool IsSpillSlot, const AllocaInst *Alloca,
                 bool IsAliased, uint8_t StackID = 0)
         : SPOffset(SPOffset), Size(Size), Alignment(Alignment),
           isImmutable(IsImmutable), isSpillSlot(IsSpillSlot), StackID(StackID),
           Alloca(Alloca), isAliased(IsAliased) {}
   };
 
   /// The alignment of the stack.
   Align StackAlignment;
 
   /// Can the stack be realigned. This can be false if the target does not
   /// support stack realignment, or if the user asks us not to realign the
   /// stack. In this situation, overaligned allocas are all treated as dynamic
   /// allocations and the target must handle them as part of DYNAMIC_STACKALLOC
   /// lowering. All non-alloca stack objects have their alignment clamped to the
   /// base ABI stack alignment.
   /// FIXME: There is room for improvement in this case, in terms of
   /// grouping overaligned allocas into a "secondary stack frame" and
   /// then only use a single alloca to allocate this frame and only a
   /// single virtual register to access it. Currently, without such an
   /// optimization, each such alloca gets its own dynamic realignment.
   bool StackRealignable;
 
   /// Whether the function has the \c alignstack attribute.
   bool ForcedRealign;
 
   /// The list of stack objects allocated.
   std::vector<StackObject> Objects;
 
   /// This contains the number of fixed objects contained on
   /// the stack.  Because fixed objects are stored at a negative index in the
   /// Objects list, this is also the index to the 0th object in the list.
   unsigned NumFixedObjects = 0;
 
   /// This boolean keeps track of whether any variable
   /// sized objects have been allocated yet.
   bool HasVarSizedObjects = false;
 
   /// This boolean keeps track of whether there is a call
   /// to builtin \@llvm.frameaddress.
   bool FrameAddressTaken = false;
 
   /// This boolean keeps track of whether there is a call
   /// to builtin \@llvm.returnaddress.
   bool ReturnAddressTaken = false;
 
   /// This boolean keeps track of whether there is a call
   /// to builtin \@llvm.experimental.stackmap.
   bool HasStackMap = false;
 
   /// This boolean keeps track of whether there is a call
   /// to builtin \@llvm.experimental.patchpoint.
   bool HasPatchPoint = false;
 
   /// The prolog/epilog code inserter calculates the final stack
   /// offsets for all of the fixed size objects, updating the Objects list
   /// above.  It then updates StackSize to contain the number of bytes that need
   /// to be allocated on entry to the function.
   uint64_t StackSize = 0;
 
   /// The amount that a frame offset needs to be adjusted to
   /// have the actual offset from the stack/frame pointer.  The exact usage of
   /// this is target-dependent, but it is typically used to adjust between
   /// SP-relative and FP-relative offsets.  E.G., if objects are accessed via
   /// SP then OffsetAdjustment is zero; if FP is used, OffsetAdjustment is set
   /// to the distance between the initial SP and the value in FP.  For many
   /// targets, this value is only used when generating debug info (via
   /// TargetRegisterInfo::getFrameIndexReference); when generating code, the
   /// corresponding adjustments are performed directly.
   int64_t OffsetAdjustment = 0;
 
   /// The prolog/epilog code inserter may process objects that require greater
   /// alignment than the default alignment the target provides.
   /// To handle this, MaxAlignment is set to the maximum alignment
   /// needed by the objects on the current frame.  If this is greater than the
   /// native alignment maintained by the compiler, dynamic alignment code will
   /// be needed.
   ///
   Align MaxAlignment;
 
   /// Set to true if this function adjusts the stack -- e.g.,
   /// when calling another function. This is only valid during and after
   /// prolog/epilog code insertion.
   bool AdjustsStack = false;
 
   /// Set to true if this function has any function calls.
   bool HasCalls = false;
 
   /// The frame index for the stack protector.
   int StackProtectorIdx = -1;
 
   /// The frame index for the function context. Used for SjLj exceptions.
   int FunctionContextIdx = -1;
 
   /// This contains the size of the largest call frame if the target uses frame
   /// setup/destroy pseudo instructions (as defined in the TargetFrameInfo
   /// class).  This information is important for frame pointer elimination.
   /// It is only valid during and after prolog/epilog code insertion.
   uint64_t MaxCallFrameSize = ~UINT64_C(0);
 
   /// The number of bytes of callee saved registers that the target wants to
   /// report for the current function in the CodeView S_FRAMEPROC record.
   unsigned CVBytesOfCalleeSavedRegisters = 0;
 
   /// The prolog/epilog code inserter fills in this vector with each
   /// callee saved register saved in either the frame or a different
   /// register.  Beyond its use by the prolog/ epilog code inserter,
   /// this data is used for debug info and exception handling.
   std::vector<CalleeSavedInfo> CSInfo;
 
   /// Has CSInfo been set yet?
   bool CSIValid = false;
 
   /// References to frame indices which are mapped
   /// into the local frame allocation block. <FrameIdx, LocalOffset>
   SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects;
 
   /// Size of the pre-allocated local frame block.
   int64_t LocalFrameSize = 0;
 
   /// Required alignment of the local object blob, which is the strictest
   /// alignment of any object in it.
   Align LocalFrameMaxAlign;
 
   /// Whether the local object blob needs to be allocated together. If not,
   /// PEI should ignore the isPreAllocated flags on the stack objects and
   /// just allocate them normally.
   bool UseLocalStackAllocationBlock = false;
 
   /// True if the function dynamically adjusts the stack pointer through some
   /// opaque mechanism like inline assembly or Win32 EH.
   bool HasOpaqueSPAdjustment = false;
 
   /// True if the function contains operations which will lower down to
   /// instructions which manipulate the stack pointer.
   bool HasCopyImplyingStackAdjustment = false;
 
   /// True if the function contains a call to the llvm.vastart intrinsic.
   bool HasVAStart = false;
 
   /// True if this is a varargs function that contains a musttail call.
   bool HasMustTailInVarArgFunc = false;
 
   /// True if this function contains a tail call. If so immutable objects like
   /// function arguments are no longer so. A tail call *can* override fixed
   /// stack objects like arguments so we can't treat them as immutable.
   bool HasTailCall = false;
 
   /// Not null, if shrink-wrapping found a better place for the prologue.
   MachineBasicBlock *Save = nullptr;
   /// Not null, if shrink-wrapping found a better place for the epilogue.
   MachineBasicBlock *Restore = nullptr;
 
   /// Size of the UnsafeStack Frame
   uint64_t UnsafeStackSize = 0;
 
 public:
   explicit MachineFrameInfo(Align StackAlignment, bool StackRealignable,
                             bool ForcedRealign)
       : StackAlignment(StackAlignment),
         StackRealignable(StackRealignable), ForcedRealign(ForcedRealign) {}
 
   MachineFrameInfo(const MachineFrameInfo &) = delete;
 
   bool isStackRealignable() const { return StackRealignable; }
 
   /// Return true if there are any stack objects in this function.
   bool hasStackObjects() const { return !Objects.empty(); }
 
   /// This method may be called any time after instruction
   /// selection is complete to determine if the stack frame for this function
   /// contains any variable sized objects.
   bool hasVarSizedObjects() const { return HasVarSizedObjects; }
 
   /// Return the index for the stack protector object.
   int getStackProtectorIndex() const { return StackProtectorIdx; }
   void setStackProtectorIndex(int I) { StackProtectorIdx = I; }
   bool hasStackProtectorIndex() const { return StackProtectorIdx != -1; }
 
   /// Return the index for the function context object.
   /// This object is used for SjLj exceptions.
   int getFunctionContextIndex() const { return FunctionContextIdx; }
   void setFunctionContextIndex(int I) { FunctionContextIdx = I; }
   bool hasFunctionContextIndex() const { return FunctionContextIdx != -1; }
 
   /// This method may be called any time after instruction
   /// selection is complete to determine if there is a call to
   /// \@llvm.frameaddress in this function.
   bool isFrameAddressTaken() const { return FrameAddressTaken; }
   void setFrameAddressIsTaken(bool T) { FrameAddressTaken = T; }
 
   /// This method may be called any time after
   /// instruction selection is complete to determine if there is a call to
   /// \@llvm.returnaddress in this function.
   bool isReturnAddressTaken() const { return ReturnAddressTaken; }
   void setReturnAddressIsTaken(bool s) { ReturnAddressTaken = s; }
 
   /// This method may be called any time after instruction
   /// selection is complete to determine if there is a call to builtin
   /// \@llvm.experimental.stackmap.
   bool hasStackMap() const { return HasStackMap; }
   void setHasStackMap(bool s = true) { HasStackMap = s; }
 
   /// This method may be called any time after instruction
   /// selection is complete to determine if there is a call to builtin
   /// \@llvm.experimental.patchpoint.
   bool hasPatchPoint() const { return HasPatchPoint; }
   void setHasPatchPoint(bool s = true) { HasPatchPoint = s; }
 
   /// Return true if this function requires a split stack prolog, even if it
   /// uses no stack space. This is only meaningful for functions where
   /// MachineFunction::shouldSplitStack() returns true.
   //
   // For non-leaf functions we have to allow for the possibility that the call
   // is to a non-split function, as in PR37807. This function could also take
   // the address of a non-split function. When the linker tries to adjust its
   // non-existent prologue, it would fail with an error. Mark the object file so
   // that such failures are not errors. See this Go language bug-report
   // https://go-review.googlesource.com/c/go/+/148819/
   bool needsSplitStackProlog() const {
     return getStackSize() != 0 || hasTailCall();
   }
 
   /// Return the minimum frame object index.
   int getObjectIndexBegin() const { return -NumFixedObjects; }
 
   /// Return one past the maximum frame object index.
   int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; }
 
   /// Return the number of fixed objects.
   unsigned getNumFixedObjects() const { return NumFixedObjects; }
 
   /// Return the number of objects.
   unsigned getNumObjects() const { return Objects.size(); }
 
   /// Map a frame index into the local object block
   void mapLocalFrameObject(int ObjectIndex, int64_t Offset) {
     LocalFrameObjects.push_back(std::pair<int, int64_t>(ObjectIndex, Offset));
     Objects[ObjectIndex + NumFixedObjects].PreAllocated = true;
   }
 
   /// Get the local offset mapping for a for an object.
   std::pair<int, int64_t> getLocalFrameObjectMap(int i) const {
     assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() &&
             "Invalid local object reference!");
     return LocalFrameObjects[i];
   }
 
   /// Return the number of objects allocated into the local object block.
   int64_t getLocalFrameObjectCount() const { return LocalFrameObjects.size(); }
 
   /// Set the size of the local object blob.
   void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; }
 
   /// Get the size of the local object blob.
   int64_t getLocalFrameSize() const { return LocalFrameSize; }
 
   /// Required alignment of the local object blob,
   /// which is the strictest alignment of any object in it.
   void setLocalFrameMaxAlign(Align Alignment) {
     LocalFrameMaxAlign = Alignment;
   }
 
   /// Return the required alignment of the local object blob.
   Align getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; }
 
   /// Get whether the local allocation blob should be allocated together or
   /// let PEI allocate the locals in it directly.
   bool getUseLocalStackAllocationBlock() const {
     return UseLocalStackAllocationBlock;
   }
 
   /// setUseLocalStackAllocationBlock - Set whether the local allocation blob
   /// should be allocated together or let PEI allocate the locals in it
   /// directly.
   void setUseLocalStackAllocationBlock(bool v) {
     UseLocalStackAllocationBlock = v;
   }
 
   /// Return true if the object was pre-allocated into the local block.
   bool isObjectPreAllocated(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].PreAllocated;
   }
 
   /// Return the size of the specified object.
   int64_t getObjectSize(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].Size;
   }
 
   /// Change the size of the specified stack object.
   void setObjectSize(int ObjectIdx, int64_t Size) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx+NumFixedObjects].Size = Size;
   }
 
   /// Return the alignment of the specified stack object.
   Align getObjectAlign(int ObjectIdx) const {
     assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx + NumFixedObjects].Alignment;
   }
 
   /// Should this stack ID be considered in MaxAlignment.
   bool contributesToMaxAlignment(uint8_t StackID) {
     return StackID == TargetStackID::Default ||
            StackID == TargetStackID::ScalableVector;
   }
 
   /// setObjectAlignment - Change the alignment of the specified stack object.
   void setObjectAlignment(int ObjectIdx, Align Alignment) {
     assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx + NumFixedObjects].Alignment = Alignment;
 
     // Only ensure max alignment for the default and scalable vector stack.
     uint8_t StackID = getStackID(ObjectIdx);
     if (contributesToMaxAlignment(StackID))
       ensureMaxAlignment(Alignment);
   }
 
   /// Return the underlying Alloca of the specified
   /// stack object if it exists. Returns 0 if none exists.
   const AllocaInst* getObjectAllocation(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].Alloca;
   }
 
   /// Remove the underlying Alloca of the specified stack object if it
   /// exists. This generally should not be used and is for reduction tooling.
   void clearObjectAllocation(int ObjectIdx) {
     assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx + NumFixedObjects].Alloca = nullptr;
   }
 
   /// Return the assigned stack offset of the specified object
   /// from the incoming stack pointer.
   int64_t getObjectOffset(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     assert(!isDeadObjectIndex(ObjectIdx) &&
            "Getting frame offset for a dead object?");
     return Objects[ObjectIdx+NumFixedObjects].SPOffset;
   }
 
   bool isObjectZExt(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].isZExt;
   }
 
   void setObjectZExt(int ObjectIdx, bool IsZExt) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx+NumFixedObjects].isZExt = IsZExt;
   }
 
   bool isObjectSExt(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].isSExt;
   }
 
   void setObjectSExt(int ObjectIdx, bool IsSExt) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx+NumFixedObjects].isSExt = IsSExt;
   }
 
   /// Set the stack frame offset of the specified object. The
   /// offset is relative to the stack pointer on entry to the function.
   void setObjectOffset(int ObjectIdx, int64_t SPOffset) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     assert(!isDeadObjectIndex(ObjectIdx) &&
            "Setting frame offset for a dead object?");
     Objects[ObjectIdx+NumFixedObjects].SPOffset = SPOffset;
   }
 
   SSPLayoutKind getObjectSSPLayout(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return (SSPLayoutKind)Objects[ObjectIdx+NumFixedObjects].SSPLayout;
   }
 
   void setObjectSSPLayout(int ObjectIdx, SSPLayoutKind Kind) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     assert(!isDeadObjectIndex(ObjectIdx) &&
            "Setting SSP layout for a dead object?");
     Objects[ObjectIdx+NumFixedObjects].SSPLayout = Kind;
   }
 
   /// Return the number of bytes that must be allocated to hold
   /// all of the fixed size frame objects.  This is only valid after
   /// Prolog/Epilog code insertion has finalized the stack frame layout.
   uint64_t getStackSize() const { return StackSize; }
 
   /// Set the size of the stack.
   void setStackSize(uint64_t Size) { StackSize = Size; }
 
   /// Estimate and return the size of the stack frame.
   uint64_t estimateStackSize(const MachineFunction &MF) const;
 
   /// Return the correction for frame offsets.
   int64_t getOffsetAdjustment() const { return OffsetAdjustment; }
 
   /// Set the correction for frame offsets.
   void setOffsetAdjustment(int64_t Adj) { OffsetAdjustment = Adj; }
 
   /// Return the alignment in bytes that this function must be aligned to,
   /// which is greater than the default stack alignment provided by the target.
   Align getMaxAlign() const { return MaxAlignment; }
 
   /// Make sure the function is at least Align bytes aligned.
   void ensureMaxAlignment(Align Alignment);
 
   /// Return true if stack realignment is forced by function attributes or if
   /// the stack alignment.
   bool shouldRealignStack() const {
     return ForcedRealign || MaxAlignment > StackAlignment;
   }
 
   /// Return true if this function adjusts the stack -- e.g.,
   /// when calling another function. This is only valid during and after
   /// prolog/epilog code insertion.
   bool adjustsStack() const { return AdjustsStack; }
   void setAdjustsStack(bool V) { AdjustsStack = V; }
 
   /// Return true if the current function has any function calls.
   bool hasCalls() const { return HasCalls; }
   void setHasCalls(bool V) { HasCalls = V; }
 
   /// Returns true if the function contains opaque dynamic stack adjustments.
   bool hasOpaqueSPAdjustment() const { return HasOpaqueSPAdjustment; }
   void setHasOpaqueSPAdjustment(bool B) { HasOpaqueSPAdjustment = B; }
 
   /// Returns true if the function contains operations which will lower down to
   /// instructions which manipulate the stack pointer.
   bool hasCopyImplyingStackAdjustment() const {
     return HasCopyImplyingStackAdjustment;
   }
   void setHasCopyImplyingStackAdjustment(bool B) {
     HasCopyImplyingStackAdjustment = B;
   }
 
   /// Returns true if the function calls the llvm.va_start intrinsic.
   bool hasVAStart() const { return HasVAStart; }
   void setHasVAStart(bool B) { HasVAStart = B; }
 
   /// Returns true if the function is variadic and contains a musttail call.
   bool hasMustTailInVarArgFunc() const { return HasMustTailInVarArgFunc; }
   void setHasMustTailInVarArgFunc(bool B) { HasMustTailInVarArgFunc = B; }
 
   /// Returns true if the function contains a tail call.
   bool hasTailCall() const { return HasTailCall; }
   void setHasTailCall(bool V = true) { HasTailCall = V; }
 
   /// Computes the maximum size of a callframe.
   /// This only works for targets defining
   /// TargetInstrInfo::getCallFrameSetupOpcode(), getCallFrameDestroyOpcode(),
   /// and getFrameSize().
   /// This is usually computed by the prologue epilogue inserter but some
   /// targets may call this to compute it earlier.
   /// If FrameSDOps is passed, the frame instructions in the MF will be
   /// inserted into it.
   void computeMaxCallFrameSize(
       MachineFunction &MF,
       std::vector<MachineBasicBlock::iterator> *FrameSDOps = nullptr);
 
   /// Return the maximum size of a call frame that must be
   /// allocated for an outgoing function call.  This is only available if
   /// CallFrameSetup/Destroy pseudo instructions are used by the target, and
   /// then only during or after prolog/epilog code insertion.
   ///
   uint64_t getMaxCallFrameSize() const {
     // TODO: Enable this assert when targets are fixed.
     //assert(isMaxCallFrameSizeComputed() && "MaxCallFrameSize not computed yet");
     if (!isMaxCallFrameSizeComputed())
       return 0;
     return MaxCallFrameSize;
   }
   bool isMaxCallFrameSizeComputed() const {
     return MaxCallFrameSize != ~UINT64_C(0);
   }
   void setMaxCallFrameSize(uint64_t S) { MaxCallFrameSize = S; }
 
   /// Returns how many bytes of callee-saved registers the target pushed in the
   /// prologue. Only used for debug info.
   unsigned getCVBytesOfCalleeSavedRegisters() const {
     return CVBytesOfCalleeSavedRegisters;
   }
   void setCVBytesOfCalleeSavedRegisters(unsigned S) {
     CVBytesOfCalleeSavedRegisters = S;
   }
 
   /// Create a new object at a fixed location on the stack.
   /// All fixed objects should be created before other objects are created for
   /// efficiency. By default, fixed objects are not pointed to by LLVM IR
   /// values. This returns an index with a negative value.
   int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool IsImmutable,
                         bool isAliased = false);
 
   /// Create a spill slot at a fixed location on the stack.
   /// Returns an index with a negative value.
   int CreateFixedSpillStackObject(uint64_t Size, int64_t SPOffset,
                                   bool IsImmutable = false);
 
   /// Returns true if the specified index corresponds to a fixed stack object.
   bool isFixedObjectIndex(int ObjectIdx) const {
     return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
   }
 
   /// Returns true if the specified index corresponds
   /// to an object that might be pointed to by an LLVM IR value.
   bool isAliasedObjectIndex(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].isAliased;
   }
 
   /// Set "maybe pointed to by an LLVM IR value" for an object.
   void setIsAliasedObjectIndex(int ObjectIdx, bool IsAliased) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx+NumFixedObjects].isAliased = IsAliased;
   }
 
   /// Returns true if the specified index corresponds to an immutable object.
   bool isImmutableObjectIndex(int ObjectIdx) const {
     // Tail calling functions can clobber their function arguments.
     if (HasTailCall)
       return false;
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].isImmutable;
   }
 
   /// Marks the immutability of an object.
   void setIsImmutableObjectIndex(int ObjectIdx, bool IsImmutable) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx+NumFixedObjects].isImmutable = IsImmutable;
   }
 
   /// Returns true if the specified index corresponds to a spill slot.
   bool isSpillSlotObjectIndex(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].isSpillSlot;
   }
 
   bool isStatepointSpillSlotObjectIndex(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot;
   }
 
   /// \see StackID
   uint8_t getStackID(int ObjectIdx) const {
     return Objects[ObjectIdx+NumFixedObjects].StackID;
   }
 
   /// \see StackID
   void setStackID(int ObjectIdx, uint8_t ID) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx+NumFixedObjects].StackID = ID;
     // If ID > 0, MaxAlignment may now be overly conservative.
     // If ID == 0, MaxAlignment will need to be updated separately.
   }
 
   /// Returns true if the specified index corresponds to a dead object.
   bool isDeadObjectIndex(int ObjectIdx) const {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx+NumFixedObjects].Size == ~0ULL;
   }
 
   /// Returns true if the specified index corresponds to a variable sized
   /// object.
   bool isVariableSizedObjectIndex(int ObjectIdx) const {
     assert(unsigned(ObjectIdx + NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     return Objects[ObjectIdx + NumFixedObjects].Size == 0;
   }
 
   void markAsStatepointSpillSlotObjectIndex(int ObjectIdx) {
     assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
            "Invalid Object Idx!");
     Objects[ObjectIdx+NumFixedObjects].isStatepointSpillSlot = true;
     assert(isStatepointSpillSlotObjectIndex(ObjectIdx) && "inconsistent");
   }
 
   /// Create a new statically sized stack object, returning
   /// a nonnegative identifier to represent it.
   int CreateStackObject(uint64_t Size, Align Alignment, bool isSpillSlot,
                         const AllocaInst *Alloca = nullptr, uint8_t ID = 0);
 
   /// Create a new statically sized stack object that represents a spill slot,
   /// returning a nonnegative identifier to represent it.
   int CreateSpillStackObject(uint64_t Size, Align Alignment);
 
   /// Remove or mark dead a statically sized stack object.
   void RemoveStackObject(int ObjectIdx) {
     // Mark it dead.
     Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL;
   }
 
   /// Notify the MachineFrameInfo object that a variable sized object has been
   /// created.  This must be created whenever a variable sized object is
   /// created, whether or not the index returned is actually used.
   int CreateVariableSizedObject(Align Alignment, const AllocaInst *Alloca);
 
   /// Returns a reference to call saved info vector for the current function.
   const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
     return CSInfo;
   }
   /// \copydoc getCalleeSavedInfo()
   std::vector<CalleeSavedInfo> &getCalleeSavedInfo() { return CSInfo; }
 
   /// Used by prolog/epilog inserter to set the function's callee saved
   /// information.
   void setCalleeSavedInfo(std::vector<CalleeSavedInfo> CSI) {
     CSInfo = std::move(CSI);
   }
 
   /// Has the callee saved info been calculated yet?
   bool isCalleeSavedInfoValid() const { return CSIValid; }
 
   void setCalleeSavedInfoValid(bool v) { CSIValid = v; }
 
   MachineBasicBlock *getSavePoint() const { return Save; }
   void setSavePoint(MachineBasicBlock *NewSave) { Save = NewSave; }
   MachineBasicBlock *getRestorePoint() const { return Restore; }
   void setRestorePoint(MachineBasicBlock *NewRestore) { Restore = NewRestore; }
 
   uint64_t getUnsafeStackSize() const { return UnsafeStackSize; }
   void setUnsafeStackSize(uint64_t Size) { UnsafeStackSize = Size; }
 
   /// Return a set of physical registers that are pristine.
   ///
   /// Pristine registers hold a value that is useless to the current function,
   /// but that must be preserved - they are callee saved registers that are not
   /// saved.
   ///
   /// Before the PrologueEpilogueInserter has placed the CSR spill code, this
   /// method always returns an empty set.
   BitVector getPristineRegs(const MachineFunction &MF) const;
 
   /// Used by the MachineFunction printer to print information about
   /// stack objects. Implemented in MachineFunction.cpp.
   void print(const MachineFunction &MF, raw_ostream &OS) const;
 
   /// dump - Print the function to stderr.
   void dump(const MachineFunction &MF) const;
 };
 
 } // End llvm namespace
 
 #endif

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