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llvm-6502/include/llvm/CodeGen/LiveInterval.h
Lang Hames 6f4e4df100 Factored out a bit of common code to mark VNInfos for deletion. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109388 91177308-0d34-0410-b5e6-96231b3b80d8
2010-07-26 01:49:41 +00:00

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//===-- llvm/CodeGen/LiveInterval.h - Interval representation ---*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file implements the LiveRange and LiveInterval classes. Given some
// numbering of each the machine instructions an interval [i, j) is said to be a
// live interval for register v if there is no instruction with number j' >= j
// such that v is live at j' and there is no instruction with number i' < i such
// that v is live at i'. In this implementation intervals can have holes,
// i.e. an interval might look like [1,20), [50,65), [1000,1001). Each
// individual range is represented as an instance of LiveRange, and the whole
// interval is represented as an instance of LiveInterval.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_LIVEINTERVAL_H
#define LLVM_CODEGEN_LIVEINTERVAL_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/Allocator.h"
#include "llvm/Support/AlignOf.h"
#include "llvm/CodeGen/SlotIndexes.h"
#include <cassert>
#include <climits>
namespace llvm {
class LiveIntervals;
class MachineInstr;
class MachineRegisterInfo;
class TargetRegisterInfo;
class raw_ostream;
/// VNInfo - Value Number Information.
/// This class holds information about a machine level values, including
/// definition and use points.
///
/// Care must be taken in interpreting the def index of the value. The
/// following rules apply:
///
/// If the isDefAccurate() method returns false then def does not contain the
/// index of the defining MachineInstr, or even (necessarily) to a
/// MachineInstr at all. In general such a def index is not meaningful
/// and should not be used. The exception is that, for values originally
/// defined by PHI instructions, after PHI elimination def will contain the
/// index of the MBB in which the PHI originally existed. This can be used
/// to insert code (spills or copies) which deals with the value, which will
/// be live in to the block.
class VNInfo {
private:
enum {
HAS_PHI_KILL = 1,
REDEF_BY_EC = 1 << 1,
IS_PHI_DEF = 1 << 2,
IS_UNUSED = 1 << 3,
IS_DEF_ACCURATE = 1 << 4
};
unsigned char flags;
union {
MachineInstr *copy;
unsigned reg;
} cr;
public:
typedef BumpPtrAllocator Allocator;
/// The ID number of this value.
unsigned id;
/// The index of the defining instruction (if isDefAccurate() returns true).
SlotIndex def;
/// VNInfo constructor.
/// d is presumed to point to the actual defining instr. If it doesn't
/// setIsDefAccurate(false) should be called after construction.
VNInfo(unsigned i, SlotIndex d, MachineInstr *c)
: flags(IS_DEF_ACCURATE), id(i), def(d) { cr.copy = c; }
/// VNInfo construtor, copies values from orig, except for the value number.
VNInfo(unsigned i, const VNInfo &orig)
: flags(orig.flags), cr(orig.cr), id(i), def(orig.def)
{ }
/// Copy from the parameter into this VNInfo.
void copyFrom(VNInfo &src) {
flags = src.flags;
cr = src.cr;
def = src.def;
}
/// Used for copying value number info.
unsigned getFlags() const { return flags; }
void setFlags(unsigned flags) { this->flags = flags; }
/// For a register interval, if this VN was definied by a copy instr
/// getCopy() returns a pointer to it, otherwise returns 0.
/// For a stack interval the behaviour of this method is undefined.
MachineInstr* getCopy() const { return cr.copy; }
/// For a register interval, set the copy member.
/// This method should not be called on stack intervals as it may lead to
/// undefined behavior.
void setCopy(MachineInstr *c) { cr.copy = c; }
/// For a stack interval, returns the reg which this stack interval was
/// defined from.
/// For a register interval the behaviour of this method is undefined.
unsigned getReg() const { return cr.reg; }
/// For a stack interval, set the defining register.
/// This method should not be called on register intervals as it may lead
/// to undefined behaviour.
void setReg(unsigned reg) { cr.reg = reg; }
/// Returns true if one or more kills are PHI nodes.
bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
/// Set the PHI kill flag on this value.
void setHasPHIKill(bool hasKill) {
if (hasKill)
flags |= HAS_PHI_KILL;
else
flags &= ~HAS_PHI_KILL;
}
/// Returns true if this value is re-defined by an early clobber somewhere
/// during the live range.
bool hasRedefByEC() const { return flags & REDEF_BY_EC; }
/// Set the "redef by early clobber" flag on this value.
void setHasRedefByEC(bool hasRedef) {
if (hasRedef)
flags |= REDEF_BY_EC;
else
flags &= ~REDEF_BY_EC;
}
/// Returns true if this value is defined by a PHI instruction (or was,
/// PHI instrucions may have been eliminated).
bool isPHIDef() const { return flags & IS_PHI_DEF; }
/// Set the "phi def" flag on this value.
void setIsPHIDef(bool phiDef) {
if (phiDef)
flags |= IS_PHI_DEF;
else
flags &= ~IS_PHI_DEF;
}
/// Returns true if this value is unused.
bool isUnused() const { return flags & IS_UNUSED; }
/// Set the "is unused" flag on this value.
void setIsUnused(bool unused) {
if (unused)
flags |= IS_UNUSED;
else
flags &= ~IS_UNUSED;
}
/// Returns true if the def is accurate.
bool isDefAccurate() const { return flags & IS_DEF_ACCURATE; }
/// Set the "is def accurate" flag on this value.
void setIsDefAccurate(bool defAccurate) {
if (defAccurate)
flags |= IS_DEF_ACCURATE;
else
flags &= ~IS_DEF_ACCURATE;
}
};
/// LiveRange structure - This represents a simple register range in the
/// program, with an inclusive start point and an exclusive end point.
/// These ranges are rendered as [start,end).
struct LiveRange {
SlotIndex start; // Start point of the interval (inclusive)
SlotIndex end; // End point of the interval (exclusive)
VNInfo *valno; // identifier for the value contained in this interval.
LiveRange(SlotIndex S, SlotIndex E, VNInfo *V)
: start(S), end(E), valno(V) {
assert(S < E && "Cannot create empty or backwards range");
}
/// contains - Return true if the index is covered by this range.
///
bool contains(SlotIndex I) const {
return start <= I && I < end;
}
/// containsRange - Return true if the given range, [S, E), is covered by
/// this range.
bool containsRange(SlotIndex S, SlotIndex E) const {
assert((S < E) && "Backwards interval?");
return (start <= S && S < end) && (start < E && E <= end);
}
bool operator<(const LiveRange &LR) const {
return start < LR.start || (start == LR.start && end < LR.end);
}
bool operator==(const LiveRange &LR) const {
return start == LR.start && end == LR.end;
}
void dump() const;
void print(raw_ostream &os) const;
private:
LiveRange(); // DO NOT IMPLEMENT
};
template <> struct isPodLike<LiveRange> { static const bool value = true; };
raw_ostream& operator<<(raw_ostream& os, const LiveRange &LR);
inline bool operator<(SlotIndex V, const LiveRange &LR) {
return V < LR.start;
}
inline bool operator<(const LiveRange &LR, SlotIndex V) {
return LR.start < V;
}
/// LiveInterval - This class represents some number of live ranges for a
/// register or value. This class also contains a bit of register allocator
/// state.
class LiveInterval {
public:
typedef SmallVector<LiveRange,4> Ranges;
typedef SmallVector<VNInfo*,4> VNInfoList;
unsigned reg; // the register or stack slot of this interval
// if the top bits is set, it represents a stack slot.
float weight; // weight of this interval
Ranges ranges; // the ranges in which this register is live
VNInfoList valnos; // value#'s
struct InstrSlots {
enum {
LOAD = 0,
USE = 1,
DEF = 2,
STORE = 3,
NUM = 4
};
};
LiveInterval(unsigned Reg, float Weight, bool IsSS = false)
: reg(Reg), weight(Weight) {
if (IsSS)
reg = reg | (1U << (sizeof(unsigned)*CHAR_BIT-1));
}
typedef Ranges::iterator iterator;
iterator begin() { return ranges.begin(); }
iterator end() { return ranges.end(); }
typedef Ranges::const_iterator const_iterator;
const_iterator begin() const { return ranges.begin(); }
const_iterator end() const { return ranges.end(); }
typedef VNInfoList::iterator vni_iterator;
vni_iterator vni_begin() { return valnos.begin(); }
vni_iterator vni_end() { return valnos.end(); }
typedef VNInfoList::const_iterator const_vni_iterator;
const_vni_iterator vni_begin() const { return valnos.begin(); }
const_vni_iterator vni_end() const { return valnos.end(); }
/// advanceTo - Advance the specified iterator to point to the LiveRange
/// containing the specified position, or end() if the position is past the
/// end of the interval. If no LiveRange contains this position, but the
/// position is in a hole, this method returns an iterator pointing to the
/// LiveRange immediately after the hole.
iterator advanceTo(iterator I, SlotIndex Pos) {
if (Pos >= endIndex())
return end();
while (I->end <= Pos) ++I;
return I;
}
void clear() {
valnos.clear();
ranges.clear();
}
/// isStackSlot - Return true if this is a stack slot interval.
///
bool isStackSlot() const {
return reg & (1U << (sizeof(unsigned)*CHAR_BIT-1));
}
/// getStackSlotIndex - Return stack slot index if this is a stack slot
/// interval.
int getStackSlotIndex() const {
assert(isStackSlot() && "Interval is not a stack slot interval!");
return reg & ~(1U << (sizeof(unsigned)*CHAR_BIT-1));
}
bool hasAtLeastOneValue() const { return !valnos.empty(); }
bool containsOneValue() const { return valnos.size() == 1; }
unsigned getNumValNums() const { return (unsigned)valnos.size(); }
/// getValNumInfo - Returns pointer to the specified val#.
///
inline VNInfo *getValNumInfo(unsigned ValNo) {
return valnos[ValNo];
}
inline const VNInfo *getValNumInfo(unsigned ValNo) const {
return valnos[ValNo];
}
/// getNextValue - Create a new value number and return it. MIIdx specifies
/// the instruction that defines the value number.
VNInfo *getNextValue(SlotIndex def, MachineInstr *CopyMI,
bool isDefAccurate, VNInfo::Allocator &VNInfoAllocator) {
VNInfo *VNI =
new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def, CopyMI);
VNI->setIsDefAccurate(isDefAccurate);
valnos.push_back(VNI);
return VNI;
}
/// Create a copy of the given value. The new value will be identical except
/// for the Value number.
VNInfo *createValueCopy(const VNInfo *orig,
VNInfo::Allocator &VNInfoAllocator) {
VNInfo *VNI =
new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), *orig);
valnos.push_back(VNI);
return VNI;
}
/// isOnlyLROfValNo - Return true if the specified live range is the only
/// one defined by the its val#.
bool isOnlyLROfValNo(const LiveRange *LR) {
for (const_iterator I = begin(), E = end(); I != E; ++I) {
const LiveRange *Tmp = I;
if (Tmp != LR && Tmp->valno == LR->valno)
return false;
}
return true;
}
/// MergeValueNumberInto - This method is called when two value nubmers
/// are found to be equivalent. This eliminates V1, replacing all
/// LiveRanges with the V1 value number with the V2 value number. This can
/// cause merging of V1/V2 values numbers and compaction of the value space.
VNInfo* MergeValueNumberInto(VNInfo *V1, VNInfo *V2);
/// MergeInClobberRanges - For any live ranges that are not defined in the
/// current interval, but are defined in the Clobbers interval, mark them
/// used with an unknown definition value. Caller must pass in reference to
/// VNInfoAllocator since it will create a new val#.
void MergeInClobberRanges(LiveIntervals &li_,
const LiveInterval &Clobbers,
VNInfo::Allocator &VNInfoAllocator);
/// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a
/// single LiveRange only.
void MergeInClobberRange(LiveIntervals &li_,
SlotIndex Start,
SlotIndex End,
VNInfo::Allocator &VNInfoAllocator);
/// MergeValueInAsValue - Merge all of the live ranges of a specific val#
/// in RHS into this live interval as the specified value number.
/// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
/// current interval, it will replace the value numbers of the overlaped
/// live ranges with the specified value number.
void MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo);
/// MergeValueInAsValue - Merge all of the live ranges of a specific val#
/// in RHS into this live interval as the specified value number.
/// The LiveRanges in RHS are allowed to overlap with LiveRanges in the
/// current interval, but only if the overlapping LiveRanges have the
/// specified value number.
void MergeValueInAsValue(const LiveInterval &RHS,
const VNInfo *RHSValNo, VNInfo *LHSValNo);
/// Copy - Copy the specified live interval. This copies all the fields
/// except for the register of the interval.
void Copy(const LiveInterval &RHS, MachineRegisterInfo *MRI,
VNInfo::Allocator &VNInfoAllocator);
bool empty() const { return ranges.empty(); }
/// beginIndex - Return the lowest numbered slot covered by interval.
SlotIndex beginIndex() const {
assert(!empty() && "Call to beginIndex() on empty interval.");
return ranges.front().start;
}
/// endNumber - return the maximum point of the interval of the whole,
/// exclusive.
SlotIndex endIndex() const {
assert(!empty() && "Call to endIndex() on empty interval.");
return ranges.back().end;
}
bool expiredAt(SlotIndex index) const {
return index >= endIndex();
}
bool liveAt(SlotIndex index) const;
// liveBeforeAndAt - Check if the interval is live at the index and the
// index just before it. If index is liveAt, check if it starts a new live
// range.If it does, then check if the previous live range ends at index-1.
bool liveBeforeAndAt(SlotIndex index) const;
/// killedAt - Return true if a live range ends at index. Note that the kill
/// point is not contained in the half-open live range. It is usually the
/// getDefIndex() slot following its last use.
bool killedAt(SlotIndex index) const;
/// killedInRange - Return true if the interval has kills in [Start,End).
/// Note that the kill point is considered the end of a live range, so it is
/// not contained in the live range. If a live range ends at End, it won't
/// be counted as a kill by this method.
bool killedInRange(SlotIndex Start, SlotIndex End) const;
/// getLiveRangeContaining - Return the live range that contains the
/// specified index, or null if there is none.
const LiveRange *getLiveRangeContaining(SlotIndex Idx) const {
const_iterator I = FindLiveRangeContaining(Idx);
return I == end() ? 0 : &*I;
}
/// getLiveRangeContaining - Return the live range that contains the
/// specified index, or null if there is none.
LiveRange *getLiveRangeContaining(SlotIndex Idx) {
iterator I = FindLiveRangeContaining(Idx);
return I == end() ? 0 : &*I;
}
/// getVNInfoAt - Return the VNInfo that is live at Idx, or NULL.
VNInfo *getVNInfoAt(SlotIndex Idx) const {
const_iterator I = FindLiveRangeContaining(Idx);
return I == end() ? 0 : I->valno;
}
/// FindLiveRangeContaining - Return an iterator to the live range that
/// contains the specified index, or end() if there is none.
const_iterator FindLiveRangeContaining(SlotIndex Idx) const;
/// FindLiveRangeContaining - Return an iterator to the live range that
/// contains the specified index, or end() if there is none.
iterator FindLiveRangeContaining(SlotIndex Idx);
/// findDefinedVNInfo - Find the by the specified
/// index (register interval) or defined
VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) const;
/// findDefinedVNInfo - Find the VNInfo that's defined by the specified
/// register (stack inteval only).
VNInfo *findDefinedVNInfoForStackInt(unsigned Reg) const;
/// overlaps - Return true if the intersection of the two live intervals is
/// not empty.
bool overlaps(const LiveInterval& other) const {
if (other.empty())
return false;
return overlapsFrom(other, other.begin());
}
/// overlaps - Return true if the live interval overlaps a range specified
/// by [Start, End).
bool overlaps(SlotIndex Start, SlotIndex End) const;
/// overlapsFrom - Return true if the intersection of the two live intervals
/// is not empty. The specified iterator is a hint that we can begin
/// scanning the Other interval starting at I.
bool overlapsFrom(const LiveInterval& other, const_iterator I) const;
/// addRange - Add the specified LiveRange to this interval, merging
/// intervals as appropriate. This returns an iterator to the inserted live
/// range (which may have grown since it was inserted.
void addRange(LiveRange LR) {
addRangeFrom(LR, ranges.begin());
}
/// join - Join two live intervals (this, and other) together. This applies
/// mappings to the value numbers in the LHS/RHS intervals as specified. If
/// the intervals are not joinable, this aborts.
void join(LiveInterval &Other,
const int *ValNoAssignments,
const int *RHSValNoAssignments,
SmallVector<VNInfo*, 16> &NewVNInfo,
MachineRegisterInfo *MRI);
/// isInOneLiveRange - Return true if the range specified is entirely in the
/// a single LiveRange of the live interval.
bool isInOneLiveRange(SlotIndex Start, SlotIndex End);
/// removeRange - Remove the specified range from this interval. Note that
/// the range must be a single LiveRange in its entirety.
void removeRange(SlotIndex Start, SlotIndex End,
bool RemoveDeadValNo = false);
void removeRange(LiveRange LR, bool RemoveDeadValNo = false) {
removeRange(LR.start, LR.end, RemoveDeadValNo);
}
/// removeValNo - Remove all the ranges defined by the specified value#.
/// Also remove the value# from value# list.
void removeValNo(VNInfo *ValNo);
/// getSize - Returns the sum of sizes of all the LiveRange's.
///
unsigned getSize() const;
/// isSpillable - Can this interval be spilled?
bool isSpillable() const {
return weight != HUGE_VALF;
}
/// markNotSpillable - Mark interval as not spillable
void markNotSpillable() {
weight = HUGE_VALF;
}
/// ComputeJoinedWeight - Set the weight of a live interval after
/// Other has been merged into it.
void ComputeJoinedWeight(const LiveInterval &Other);
bool operator<(const LiveInterval& other) const {
const SlotIndex &thisIndex = beginIndex();
const SlotIndex &otherIndex = other.beginIndex();
return (thisIndex < otherIndex ||
(thisIndex == otherIndex && reg < other.reg));
}
void print(raw_ostream &OS, const TargetRegisterInfo *TRI = 0) const;
void dump() const;
private:
Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
void extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd);
Ranges::iterator extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStr);
void markValNoForDeletion(VNInfo *V);
LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
};
inline raw_ostream &operator<<(raw_ostream &OS, const LiveInterval &LI) {
LI.print(OS);
return OS;
}
}
#endif
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