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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/IntEqClasses.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.
///
class VNInfo {
private:
enum {
HAS_PHI_KILL = 1,
IS_PHI_DEF = 1 << 1,
IS_UNUSED = 1 << 2
};
unsigned char flags;
public:
typedef BumpPtrAllocator Allocator;
/// The ID number of this value.
unsigned id;
/// The index of the defining instruction.
SlotIndex def;
/// VNInfo constructor.
VNInfo(unsigned i, SlotIndex d)
: flags(0), id(i), def(d)
{ }
/// VNInfo construtor, copies values from orig, except for the value number.
VNInfo(unsigned i, const VNInfo &orig)
: flags(orig.flags), id(i), def(orig.def)
{ }
/// Copy from the parameter into this VNInfo.
void copyFrom(VNInfo &src) {
flags = src.flags;
def = src.def;
}
/// Used for copying value number info.
unsigned getFlags() const { return flags; }
void setFlags(unsigned flags) { this->flags = flags; }
/// Merge flags from another VNInfo
void mergeFlags(const VNInfo *VNI) {
flags = (flags | VNI->flags) & ~IS_UNUSED;
}
/// Returns true if one or more kills are PHI nodes.
/// Obsolete, do not use!
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 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;
}
};
/// 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;
const unsigned reg; // the register or stack slot of this interval.
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)
: reg(Reg), weight(Weight) {}
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) {
assert(I != end());
if (Pos >= endIndex())
return end();
while (I->end <= Pos) ++I;
return I;
}
/// find - Return an iterator pointing to the first range that ends after
/// Pos, or end(). This is the same as advanceTo(begin(), Pos), but faster
/// when searching large intervals.
///
/// If Pos is contained in a LiveRange, that range is returned.
/// If Pos is in a hole, the following LiveRange is returned.
/// If Pos is beyond endIndex, end() is returned.
iterator find(SlotIndex Pos);
const_iterator find(SlotIndex Pos) const {
return const_cast<LiveInterval*>(this)->find(Pos);
}
void clear() {
valnos.clear();
ranges.clear();
}
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];
}
/// containsValue - Returns true if VNI belongs to this interval.
bool containsValue(const VNInfo *VNI) const {
return VNI && VNI->id < getNumValNums() && VNI == getValNumInfo(VNI->id);
}
/// getNextValue - Create a new value number and return it. MIIdx specifies
/// the instruction that defines the value number.
VNInfo *getNextValue(SlotIndex def, VNInfo::Allocator &VNInfoAllocator) {
VNInfo *VNI =
new (VNInfoAllocator) VNInfo((unsigned)valnos.size(), def);
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;
}
/// RenumberValues - Renumber all values in order of appearance and remove
/// unused values.
void RenumberValues(LiveIntervals &lis);
/// 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);
/// 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 {
const_iterator r = find(index);
return r != end() && r->start <= index;
}
/// 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 {
const_iterator r = find(index.getRegSlot(true));
return r != end() && r->end == index;
}
/// 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;
}
const LiveRange *getLiveRangeBefore(SlotIndex Idx) const {
return getLiveRangeContaining(Idx.getPrevSlot());
}
LiveRange *getLiveRangeBefore(SlotIndex Idx) {
return getLiveRangeContaining(Idx.getPrevSlot());
}
/// 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;
}
/// getVNInfoBefore - Return the VNInfo that is live up to but not
/// necessarilly including Idx, or NULL. Use this to find the reaching def
/// used by an instruction at this SlotIndex position.
VNInfo *getVNInfoBefore(SlotIndex Idx) const {
const_iterator I = FindLiveRangeContaining(Idx.getPrevSlot());
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.
iterator FindLiveRangeContaining(SlotIndex Idx) {
iterator I = find(Idx);
return I != end() && I->start <= Idx ? I : end();
}
const_iterator FindLiveRangeContaining(SlotIndex Idx) const {
const_iterator I = find(Idx);
return I != end() && I->start <= Idx ? I : end();
}
/// findDefinedVNInfo - Find the by the specified
/// index (register interval) or defined
VNInfo *findDefinedVNInfoForRegInt(SlotIndex Idx) 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());
}
/// extendInBlock - If this interval is live before Kill in the basic block
/// that starts at StartIdx, extend it to be live up to Kill, and return
/// the value. If there is no live range before Kill, return NULL.
VNInfo *extendInBlock(SlotIndex StartIdx, SlotIndex Kill);
/// 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) const {
const_iterator r = find(Start);
return r != end() && r->containsRange(Start, 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;
/// Returns true if the live interval is zero length, i.e. no live ranges
/// span instructions. It doesn't pay to spill such an interval.
bool isZeroLength(SlotIndexes *Indexes) const {
for (const_iterator i = begin(), e = end(); i != e; ++i)
if (Indexes->getNextNonNullIndex(i->start).getBaseIndex() <
i->end.getBaseIndex())
return false;
return true;
}
/// 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;
}
/// ConnectedVNInfoEqClasses - Helper class that can divide VNInfos in a
/// LiveInterval into equivalence clases of connected components. A
/// LiveInterval that has multiple connected components can be broken into
/// multiple LiveIntervals.
///
/// Given a LiveInterval that may have multiple connected components, run:
///
/// unsigned numComps = ConEQ.Classify(LI);
/// if (numComps > 1) {
/// // allocate numComps-1 new LiveIntervals into LIS[1..]
/// ConEQ.Distribute(LIS);
/// }
class ConnectedVNInfoEqClasses {
LiveIntervals &LIS;
IntEqClasses EqClass;
// Note that values a and b are connected.
void Connect(unsigned a, unsigned b);
unsigned Renumber();
public:
explicit ConnectedVNInfoEqClasses(LiveIntervals &lis) : LIS(lis) {}
/// Classify - Classify the values in LI into connected components.
/// Return the number of connected components.
unsigned Classify(const LiveInterval *LI);
/// getEqClass - Classify creates equivalence classes numbered 0..N. Return
/// the equivalence class assigned the VNI.
unsigned getEqClass(const VNInfo *VNI) const { return EqClass[VNI->id]; }
/// Distribute - Distribute values in LIV[0] into a separate LiveInterval
/// for each connected component. LIV must have a LiveInterval for each
/// connected component. The LiveIntervals in Liv[1..] must be empty.
/// Instructions using LIV[0] are rewritten.
void Distribute(LiveInterval *LIV[], MachineRegisterInfo &MRI);
};
}
#endif