llvm-6502/include/llvm/CodeGen/MachineFrameInfo.h
Jim Grosbach 3d72367d30 Add a local stack object block allocation pass. This is still an
experimental pass that allocates locals relative to one another before
register allocation and then assigns them to actual stack slots as a block
later in PEI. This will eventually allow targets with limited index offset
range to allocate additional base registers (not just FP and SP) to
more efficiently reference locals, as well as handle situations where
locals cannot be referenced via SP or FP at all (dynamic stack realignment
together with variable sized objects, for example). It's currently
incomplete and almost certainly buggy. Work in progress.

Disabled by default and gated via the -enable-local-stack-alloc command
line option.

rdar://8277890



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@111059 91177308-0d34-0410-b5e6-96231b3b80d8
2010-08-14 00:15:52 +00:00

537 lines
21 KiB
C++

//===-- 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/ADT/IndexedMap.h"
#include "llvm/System/DataTypes.h"
#include <cassert>
#include <vector>
namespace llvm {
class raw_ostream;
class TargetData;
class TargetRegisterClass;
class Type;
class MachineFunction;
class MachineBasicBlock;
class TargetFrameInfo;
class BitVector;
/// The CalleeSavedInfo class tracks the information need to locate where a
/// callee saved register 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;
// MayNeedSP - If true the stack object triggered the creation of the stack
// protector. We should allocate this object right after the stack
// protector.
bool MayNeedSP;
// PreAllocated - If true, the object was mapped into the local frame
// block and doesn't need additional handling for allocation beyond that.
bool PreAllocated;
StackObject(uint64_t Sz, unsigned Al, int64_t SP, bool IM,
bool isSS, bool NSP)
: SPOffset(SP), Size(Sz), Alignment(Al), isImmutable(IM),
isSpillSlot(isSS), MayNeedSP(NSP), PreAllocated(false) {}
};
/// Objects - The list of stack objects allocated...
///
std::vector<StackObject> 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;
/// 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;
/// 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<CalleeSavedInfo> CSInfo;
/// CSIValid - Has CSInfo been set yet?
bool CSIValid;
/// SpillObjects - A vector indicating which frame indices refer to
/// spill slots.
SmallVector<bool, 8> SpillObjects;
/// TargetFrameInfo - Target information about frame layout.
///
const TargetFrameInfo &TFI;
/// LocalFrameObjects - References to frame indices which are mapped
/// into the local frame allocation block. <FrameIdx, LocalOffset>
SmallVector<std::pair<int, int64_t>, 32> LocalFrameObjects;
/// LocalFrameSize - Size of the pre-allocated local frame block.
int64_t LocalFrameSize;
/// LocalFrameBaseOffset - The base offset from the stack pointer at
/// function entry of the local frame blob. Set by PEI for use by
/// target in eliminateFrameIndex().
int64_t LocalFrameBaseOffset;
public:
explicit MachineFrameInfo(const TargetFrameInfo &tfi) : TFI(tfi) {
StackSize = NumFixedObjects = OffsetAdjustment = MaxAlignment = 0;
HasVarSizedObjects = false;
FrameAddressTaken = false;
ReturnAddressTaken = false;
AdjustsStack = false;
HasCalls = false;
StackProtectorIdx = -1;
MaxCallFrameSize = 0;
CSIValid = false;
LocalFrameSize = 0;
LocalFrameBaseOffset = 0;
}
/// 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; }
/// 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; }
/// 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<int, int64_t>(ObjectIndex, Offset));
Objects[ObjectIndex + NumFixedObjects].PreAllocated = true;
}
/// getLocalFrameObjectMap - Get the local offset mapping for a for an object
std::pair<int, int64_t> 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(); }
/// setLocalFrameBaseOffset - Set the base SP offset of the local frame
/// blob.
void setLocalFrameBaseOffset(int64_t o) { LocalFrameBaseOffset = o; }
/// getLocalFrameBaseOffset - Get the base SP offset of the local frame
/// blob.
int64_t getLocalFrameBaseOffset() const { return LocalFrameBaseOffset; }
/// getLocalFrameSize - Get the size of the local object blob.
int64_t getLocalFrameSize() const { return LocalFrameSize; }
/// 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;
MaxAlignment = std::max(MaxAlignment, Align);
}
/// NeedsStackProtector - Returns true if the object may need stack
/// protectors.
bool MayNeedStackProtector(int ObjectIdx) const {
assert(unsigned(ObjectIdx+NumFixedObjects) < Objects.size() &&
"Invalid Object Idx!");
return Objects[ObjectIdx+NumFixedObjects].MayNeedSP;
}
/// 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; }
/// 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; }
/// setMaxAlignment - Set the preferred alignment.
///
void setMaxAlignment(unsigned Align) { MaxAlignment = 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; }
/// 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 immutable. This returns an
/// index with a negative value.
///
int CreateFixedObject(uint64_t Size, int64_t SPOffset, bool Immutable);
/// isFixedObjectIndex - Returns true if the specified index corresponds to a
/// fixed stack object.
bool isFixedObjectIndex(int ObjectIdx) const {
return ObjectIdx < 0 && (ObjectIdx >= -(int)NumFixedObjects);
}
/// 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,
bool MayNeedSP = false) {
assert(Size != 0 && "Cannot allocate zero size stack objects!");
Objects.push_back(StackObject(Size, Alignment, 0, false, isSS, MayNeedSP));
int Index = (int)Objects.size() - NumFixedObjects - 1;
assert(Index >= 0 && "Bad frame index!");
MaxAlignment = std::max(MaxAlignment, Alignment);
return Index;
}
/// 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) {
CreateStackObject(Size, Alignment, true, false);
int Index = (int)Objects.size() - NumFixedObjects - 1;
MaxAlignment = std::max(MaxAlignment, Alignment);
return Index;
}
/// 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) {
HasVarSizedObjects = true;
Objects.push_back(StackObject(0, Alignment, 0, false, false, true));
MaxAlignment = std::max(MaxAlignment, Alignment);
return (int)Objects.size()-NumFixedObjects-1;
}
/// getCalleeSavedInfo - Returns a reference to call saved info vector for the
/// current function.
const std::vector<CalleeSavedInfo> &getCalleeSavedInfo() const {
return CSInfo;
}
/// setCalleeSavedInfo - Used by prolog/epilog inserter to set the function's
/// callee saved information.
void setCalleeSavedInfo(const std::vector<CalleeSavedInfo> &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