//===-- 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.
int 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.
unsigned MaxCallFrameSize = ~0u;
/// 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;
/// 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.
int getOffsetAdjustment() const { return OffsetAdjustment; }
/// Set the correction for frame offsets.
void setOffsetAdjustment(int 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 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 and the AdjustsStack property.
/// 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.
void computeMaxCallFrameSize(const MachineFunction &MF);
/// 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 {
// 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 != ~0u;
}
void setMaxCallFrameSize(unsigned 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;
}
/// 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