//===-- CodeGen/MachineFrameInfo.h - Abstract Stack Frame Rep. --*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // The file defines the MachineFrameInfo class. // //===----------------------------------------------------------------------===// #ifndef LLVM_CODEGEN_MACHINEFRAMEINFO_H #define LLVM_CODEGEN_MACHINEFRAMEINFO_H #include "llvm/ADT/SmallVector.h" #include "llvm/Support/DataTypes.h" #include #include namespace llvm { class raw_ostream; class DataLayout; class TargetRegisterClass; class Type; class MachineFunction; class MachineBasicBlock; class TargetFrameLowering; class TargetMachine; class BitVector; class Value; class AllocaInst; /// The CalleeSavedInfo class tracks the information need to locate where a /// callee saved register is in the current frame. class CalleeSavedInfo { unsigned Reg; int FrameIdx; public: explicit CalleeSavedInfo(unsigned R, int FI = 0) : Reg(R), FrameIdx(FI) {} // Accessors. unsigned getReg() const { return Reg; } int getFrameIdx() const { return FrameIdx; } void setFrameIdx(int FI) { FrameIdx = FI; } }; /// 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. /// /// @brief Abstract Stack Frame Information class MachineFrameInfo { // StackObject - Represent a single object allocated on the stack. struct StackObject { // SPOffset - 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; // Alignment - The required alignment of this stack slot. unsigned Alignment; // isImmutable - 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; // isSpillSlot - If true the stack object is used as spill slot. It // cannot alias any other memory objects. bool isSpillSlot; /// Alloca - If this stack object is originated from an Alloca instruction /// this value saves the original IR allocation. Can be NULL. const AllocaInst *Alloca; // PreAllocated - If true, the object was mapped into the local frame // block and doesn't need additional handling for allocation beyond that. bool PreAllocated; // 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; StackObject(uint64_t Sz, unsigned Al, int64_t SP, bool IM, bool isSS, const AllocaInst *Val, bool A) : SPOffset(SP), Size(Sz), Alignment(Al), isImmutable(IM), isSpillSlot(isSS), Alloca(Val), PreAllocated(false), isAliased(A) {} }; const TargetMachine &TM; /// Objects - The list of stack objects allocated... /// std::vector Objects; /// NumFixedObjects - 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; /// HasVarSizedObjects - This boolean keeps track of whether any variable /// sized objects have been allocated yet. /// bool HasVarSizedObjects; /// FrameAddressTaken - This boolean keeps track of whether there is a call /// to builtin \@llvm.frameaddress. bool FrameAddressTaken; /// ReturnAddressTaken - This boolean keeps track of whether there is a call /// to builtin \@llvm.returnaddress. bool ReturnAddressTaken; /// HasStackMap - This boolean keeps track of whether there is a call /// to builtin \@llvm.experimental.stackmap. bool HasStackMap; /// HasPatchPoint - This boolean keeps track of whether there is a call /// to builtin \@llvm.experimental.patchpoint. bool HasPatchPoint; /// StackSize - 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; /// OffsetAdjustment - 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::getFrameIndexOffset); when generating code, the /// corresponding adjustments are performed directly. int OffsetAdjustment; /// MaxAlignment - 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. /// unsigned MaxAlignment; /// AdjustsStack - 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; /// HasCalls - Set to true if this function has any function calls. bool HasCalls; /// StackProtectorIdx - The frame index for the stack protector. int StackProtectorIdx; /// FunctionContextIdx - The frame index for the function context. Used for /// SjLj exceptions. int FunctionContextIdx; /// MaxCallFrameSize - 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. If is only valid during and after prolog/epilog code /// insertion. /// unsigned MaxCallFrameSize; /// CSInfo - The prolog/epilog code inserter fills in this vector with each /// callee saved register saved in the frame. Beyond its use by the prolog/ /// epilog code inserter, this data used for debug info and exception /// handling. std::vector CSInfo; /// CSIValid - Has CSInfo been set yet? bool CSIValid; /// LocalFrameObjects - References to frame indices which are mapped /// into the local frame allocation block. SmallVector, 32> LocalFrameObjects; /// LocalFrameSize - Size of the pre-allocated local frame block. int64_t LocalFrameSize; /// Required alignment of the local object blob, which is the strictest /// alignment of any object in it. unsigned 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; /// Whether the "realign-stack" option is on. bool RealignOption; /// True if the function includes inline assembly that adjusts the stack /// pointer. bool HasInlineAsmWithSPAdjust; /// True if the function contains a call to the llvm.vastart intrinsic. bool HasVAStart; /// True if this is a varargs function that contains a musttail call. bool HasMustTailInVarArgFunc; const TargetFrameLowering *getFrameLowering() const; public: explicit MachineFrameInfo(const TargetMachine &TM, bool RealignOpt) : TM(TM), RealignOption(RealignOpt) { StackSize = NumFixedObjects = OffsetAdjustment = MaxAlignment = 0; HasVarSizedObjects = false; FrameAddressTaken = false; ReturnAddressTaken = false; HasStackMap = false; HasPatchPoint = false; AdjustsStack = false; HasCalls = false; StackProtectorIdx = -1; FunctionContextIdx = -1; MaxCallFrameSize = 0; CSIValid = false; LocalFrameSize = 0; LocalFrameMaxAlign = 0; UseLocalStackAllocationBlock = false; HasInlineAsmWithSPAdjust = false; HasVAStart = false; HasMustTailInVarArgFunc = false; } /// hasStackObjects - Return true if there are any stack objects in this /// function. /// bool hasStackObjects() const { return !Objects.empty(); } /// hasVarSizedObjects - 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; } /// getStackProtectorIndex/setStackProtectorIndex - Return the index for the /// stack protector object. /// int getStackProtectorIndex() const { return StackProtectorIdx; } void setStackProtectorIndex(int I) { StackProtectorIdx = I; } /// getFunctionContextIndex/setFunctionContextIndex - 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; } /// isFrameAddressTaken - 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; } /// isReturnAddressTaken - 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; } /// hasStackMap - 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; } /// hasPatchPoint - 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; } /// getObjectIndexBegin - Return the minimum frame object index. /// int getObjectIndexBegin() const { return -NumFixedObjects; } /// getObjectIndexEnd - Return one past the maximum frame object index. /// int getObjectIndexEnd() const { return (int)Objects.size()-NumFixedObjects; } /// getNumFixedObjects - Return the number of fixed objects. unsigned getNumFixedObjects() const { return NumFixedObjects; } /// getNumObjects - Return the number of objects. /// unsigned getNumObjects() const { return Objects.size(); } /// mapLocalFrameObject - Map a frame index into the local object block void mapLocalFrameObject(int ObjectIndex, int64_t Offset) { LocalFrameObjects.push_back(std::pair(ObjectIndex, Offset)); Objects[ObjectIndex + NumFixedObjects].PreAllocated = true; } /// getLocalFrameObjectMap - Get the local offset mapping for a for an object std::pair getLocalFrameObjectMap(int i) { assert (i >= 0 && (unsigned)i < LocalFrameObjects.size() && "Invalid local object reference!"); return LocalFrameObjects[i]; } /// getLocalFrameObjectCount - Return the number of objects allocated into /// the local object block. int64_t getLocalFrameObjectCount() { return LocalFrameObjects.size(); } /// setLocalFrameSize - Set the size of the local object blob. void setLocalFrameSize(int64_t sz) { LocalFrameSize = sz; } /// getLocalFrameSize - Get the size of the local object blob. int64_t getLocalFrameSize() const { return LocalFrameSize; } /// setLocalFrameMaxAlign - Required alignment of the local object blob, /// which is the strictest alignment of any object in it. void setLocalFrameMaxAlign(unsigned Align) { LocalFrameMaxAlign = Align; } /// getLocalFrameMaxAlign - Return the required alignment of the local /// object blob. unsigned getLocalFrameMaxAlign() const { return LocalFrameMaxAlign; } /// getUseLocalStackAllocationBlock - Get whether the local allocation blob /// should be allocated together or let PEI allocate the locals in it /// directly. bool getUseLocalStackAllocationBlock() {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; } /// isObjectPreAllocated - 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; } /// getObjectSize - 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; } /// setObjectSize - 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; } /// getObjectAlignment - Return the alignment of the specified stack object. unsigned getObjectAlignment(int ObjectIdx) const { assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && "Invalid Object Idx!"); return Objects[ObjectIdx+NumFixedObjects].Alignment; } /// setObjectAlignment - Change the alignment of the specified stack object. void setObjectAlignment(int ObjectIdx, unsigned Align) { assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && "Invalid Object Idx!"); Objects[ObjectIdx+NumFixedObjects].Alignment = Align; ensureMaxAlignment(Align); } /// getObjectAllocation - 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; } /// getObjectOffset - 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; } /// setObjectOffset - 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; } /// getStackSize - 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; } /// setStackSize - Set the size of the stack... /// void setStackSize(uint64_t Size) { StackSize = Size; } /// Estimate and return the size of the stack frame. unsigned estimateStackSize(const MachineFunction &MF) const; /// getOffsetAdjustment - Return the correction for frame offsets. /// int getOffsetAdjustment() const { return OffsetAdjustment; } /// setOffsetAdjustment - Set the correction for frame offsets. /// void setOffsetAdjustment(int Adj) { OffsetAdjustment = Adj; } /// getMaxAlignment - Return the alignment in bytes that this function must be /// aligned to, which is greater than the default stack alignment provided by /// the target. /// unsigned getMaxAlignment() const { return MaxAlignment; } /// ensureMaxAlignment - Make sure the function is at least Align bytes /// aligned. void ensureMaxAlignment(unsigned Align); /// AdjustsStack - 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; } /// hasCalls - 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 any stack-adjusting inline assembly. bool hasInlineAsmWithSPAdjust() const { return HasInlineAsmWithSPAdjust; } void setHasInlineAsmWithSPAdjust(bool B) { HasInlineAsmWithSPAdjust = 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; } /// getMaxCallFrameSize - 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. /// unsigned getMaxCallFrameSize() const { return MaxCallFrameSize; } void setMaxCallFrameSize(unsigned S) { MaxCallFrameSize = S; } /// CreateFixedObject - 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 Immutable, bool isAliased = false); /// CreateFixedSpillStackObject - 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); /// isFixedObjectIndex - Returns true if the specified index corresponds to a /// fixed stack object. bool isFixedObjectIndex(int ObjectIdx) const { return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects); } /// isAliasedObjectIndex - 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; } /// isImmutableObjectIndex - Returns true if the specified index corresponds /// to an immutable object. bool isImmutableObjectIndex(int ObjectIdx) const { assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() && "Invalid Object Idx!"); return Objects[ObjectIdx+NumFixedObjects].isImmutable; } /// isSpillSlotObjectIndex - 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; } /// isDeadObjectIndex - 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; } /// CreateStackObject - Create a new statically sized stack object, returning /// a nonnegative identifier to represent it. /// int CreateStackObject(uint64_t Size, unsigned Alignment, bool isSS, const AllocaInst *Alloca = nullptr); /// CreateSpillStackObject - Create a new statically sized stack object that /// represents a spill slot, returning a nonnegative identifier to represent /// it. /// int CreateSpillStackObject(uint64_t Size, unsigned Alignment); /// RemoveStackObject - Remove or mark dead a statically sized stack object. /// void RemoveStackObject(int ObjectIdx) { // Mark it dead. Objects[ObjectIdx+NumFixedObjects].Size = ~0ULL; } /// CreateVariableSizedObject - 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(unsigned Alignment, const AllocaInst *Alloca); /// getCalleeSavedInfo - Returns a reference to call saved info vector for the /// current function. const std::vector &getCalleeSavedInfo() const { return CSInfo; } /// setCalleeSavedInfo - Used by prolog/epilog inserter to set the function's /// callee saved information. void setCalleeSavedInfo(const std::vector &CSI) { CSInfo = CSI; } /// isCalleeSavedInfoValid - Has the callee saved info been calculated yet? bool isCalleeSavedInfoValid() const { return CSIValid; } void setCalleeSavedInfoValid(bool v) { CSIValid = v; } /// getPristineRegs - Return a set of physical registers that are pristine on /// entry to the MBB. /// /// Pristine registers hold a value that is useless to the current function, /// but that must be preserved - they are callee saved registers that have not /// been saved yet. /// /// Before the PrologueEpilogueInserter has placed the CSR spill code, this /// method always returns an empty set. BitVector getPristineRegs(const MachineBasicBlock *MBB) const; /// print - 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