llvm-6502/include/llvm/CodeGen/LiveInterval.h
2009-07-15 21:52:40 +00:00

601 lines
21 KiB
C++

//===-- 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 <iosfwd>
#include <cassert>
#include <climits>
namespace llvm {
class MachineInstr;
class MachineRegisterInfo;
class TargetRegisterInfo;
/// 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;
public:
/// Holds information about individual kills.
struct KillInfo {
bool isPHIKill : 1;
unsigned killIdx : 31;
KillInfo(bool isPHIKill, unsigned killIdx)
: isPHIKill(isPHIKill), killIdx(killIdx) {
assert(killIdx != 0 && "Zero kill indices are no longer permitted.");
}
};
typedef SmallVector<KillInfo, 4> KillSet;
/// The ID number of this value.
unsigned id;
/// The index of the defining instruction (if isDefAccurate() returns true).
unsigned def;
MachineInstr *copy;
KillSet kills;
VNInfo()
: flags(IS_UNUSED), id(~1U), def(0), copy(0) {}
/// 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, unsigned d, MachineInstr *c)
: flags(IS_DEF_ACCURATE), id(i), def(d), copy(c) {}
/// 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(orig.copy),
kills(orig.kills) {}
/// Used for copying value number info.
unsigned getFlags() const { return flags; }
void setFlags(unsigned flags) { this->flags = flags; }
/// Returns true if one or more kills are PHI nodes.
bool hasPHIKill() const { return flags & HAS_PHI_KILL; }
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; }
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; }
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; }
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; }
void setIsDefAccurate(bool defAccurate) {
if (defAccurate)
flags |= IS_DEF_ACCURATE;
else
flags &= ~IS_DEF_ACCURATE;
}
};
inline bool operator<(const VNInfo::KillInfo &k1, const VNInfo::KillInfo &k2) {
return k1.killIdx < k2.killIdx;
}
inline bool operator<(const VNInfo::KillInfo &k, unsigned idx) {
return k.killIdx < idx;
}
inline bool operator<(unsigned idx, const VNInfo::KillInfo &k) {
return idx < k.killIdx;
}
/// 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 {
unsigned start; // Start point of the interval (inclusive)
unsigned end; // End point of the interval (exclusive)
VNInfo *valno; // identifier for the value contained in this interval.
LiveRange(unsigned S, unsigned 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(unsigned I) const {
return start <= I && I < 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(std::ostream &os) const;
void print(std::ostream *os) const { if (os) print(*os); }
private:
LiveRange(); // DO NOT IMPLEMENT
};
std::ostream& operator<<(std::ostream& os, const LiveRange &LR);
inline bool operator<(unsigned V, const LiveRange &LR) {
return V < LR.start;
}
inline bool operator<(const LiveRange &LR, unsigned 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
};
static unsigned scale(unsigned slot, unsigned factor) {
unsigned index = slot / NUM,
offset = slot % NUM;
assert(index <= ~0U / (factor * NUM) &&
"Rescaled interval would overflow");
return index * NUM * factor + offset;
}
};
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 the the
/// LiveRange immediately after the hole.
iterator advanceTo(iterator I, unsigned Pos) {
if (Pos >= endNumber())
return end();
while (I->end <= Pos) ++I;
return I;
}
void clear() {
while (!valnos.empty()) {
VNInfo *VNI = valnos.back();
valnos.pop_back();
VNI->~VNInfo();
}
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];
}
/// copyValNumInfo - Copy the value number info for one value number to
/// another.
void copyValNumInfo(VNInfo *DstValNo, const VNInfo *SrcValNo) {
DstValNo->def = SrcValNo->def;
DstValNo->copy = SrcValNo->copy;
DstValNo->setFlags(SrcValNo->getFlags());
DstValNo->kills = SrcValNo->kills;
}
/// getNextValue - Create a new value number and return it. MIIdx specifies
/// the instruction that defines the value number.
VNInfo *getNextValue(unsigned MIIdx, MachineInstr *CopyMI,
bool isDefAccurate, BumpPtrAllocator &VNInfoAllocator) {
assert(MIIdx != ~0u && MIIdx != ~1u &&
"PHI def / unused flags should now be passed explicitly.");
VNInfo *VNI =
static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo),
alignof<VNInfo>()));
new (VNI) VNInfo((unsigned)valnos.size(), MIIdx, 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, BumpPtrAllocator &VNInfoAllocator) {
VNInfo *VNI =
static_cast<VNInfo*>(VNInfoAllocator.Allocate((unsigned)sizeof(VNInfo),
alignof<VNInfo>()));
new (VNI) VNInfo((unsigned)valnos.size(), *orig);
valnos.push_back(VNI);
return VNI;
}
/// addKill - Add a kill instruction index to the specified value
/// number.
static void addKill(VNInfo *VNI, unsigned KillIdx, bool phiKill) {
VNInfo::KillSet &kills = VNI->kills;
VNInfo::KillInfo newKill(phiKill, KillIdx);
if (kills.empty()) {
kills.push_back(newKill);
} else {
VNInfo::KillSet::iterator
I = std::lower_bound(kills.begin(), kills.end(), newKill);
kills.insert(I, newKill);
}
}
/// addKills - Add a number of kills into the VNInfo kill vector. If this
/// interval is live at a kill point, then the kill is not added.
void addKills(VNInfo *VNI, const VNInfo::KillSet &kills) {
for (unsigned i = 0, e = static_cast<unsigned>(kills.size());
i != e; ++i) {
const VNInfo::KillInfo &Kill = kills[i];
if (!liveBeforeAndAt(Kill.killIdx)) {
VNInfo::KillSet::iterator
I = std::lower_bound(VNI->kills.begin(), VNI->kills.end(), Kill);
VNI->kills.insert(I, Kill);
}
}
}
/// removeKill - Remove the specified kill from the list of kills of
/// the specified val#.
static bool removeKill(VNInfo *VNI, unsigned KillIdx) {
VNInfo::KillSet &kills = VNI->kills;
VNInfo::KillSet::iterator
I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
if (I != kills.end() && I->killIdx == KillIdx) {
kills.erase(I);
return true;
}
return false;
}
/// removeKills - Remove all the kills in specified range
/// [Start, End] of the specified val#.
static void removeKills(VNInfo *VNI, unsigned Start, unsigned End) {
VNInfo::KillSet &kills = VNI->kills;
VNInfo::KillSet::iterator
I = std::lower_bound(kills.begin(), kills.end(), Start);
VNInfo::KillSet::iterator
E = std::upper_bound(kills.begin(), kills.end(), End);
kills.erase(I, E);
}
/// isKill - Return true if the specified index is a kill of the
/// specified val#.
static bool isKill(const VNInfo *VNI, unsigned KillIdx) {
const VNInfo::KillSet &kills = VNI->kills;
VNInfo::KillSet::const_iterator
I = std::lower_bound(kills.begin(), kills.end(), KillIdx);
return I != kills.end() && I->killIdx == KillIdx;
}
/// 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(const LiveInterval &Clobbers,
BumpPtrAllocator &VNInfoAllocator);
/// MergeInClobberRange - Same as MergeInClobberRanges except it merge in a
/// single LiveRange only.
void MergeInClobberRange(unsigned Start, unsigned End,
BumpPtrAllocator &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,
BumpPtrAllocator &VNInfoAllocator);
bool empty() const { return ranges.empty(); }
/// beginNumber - Return the lowest numbered slot covered by interval.
unsigned beginNumber() const {
if (empty())
return 0;
return ranges.front().start;
}
/// endNumber - return the maximum point of the interval of the whole,
/// exclusive.
unsigned endNumber() const {
if (empty())
return 0;
return ranges.back().end;
}
bool expiredAt(unsigned index) const {
return index >= endNumber();
}
bool liveAt(unsigned 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(unsigned index) const;
/// getLiveRangeContaining - Return the live range that contains the
/// specified index, or null if there is none.
const LiveRange *getLiveRangeContaining(unsigned 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(unsigned Idx) {
iterator I = FindLiveRangeContaining(Idx);
return I == end() ? 0 : &*I;
}
/// FindLiveRangeContaining - Return an iterator to the live range that
/// contains the specified index, or end() if there is none.
const_iterator FindLiveRangeContaining(unsigned Idx) const;
/// FindLiveRangeContaining - Return an iterator to the live range that
/// contains the specified index, or end() if there is none.
iterator FindLiveRangeContaining(unsigned Idx);
/// findDefinedVNInfo - Find the VNInfo that's defined at the specified
/// index (register interval) or defined by the specified register (stack
/// inteval).
VNInfo *findDefinedVNInfo(unsigned DefIdxOrReg) const;
/// overlaps - Return true if the intersection of the two live intervals is
/// not empty.
bool overlaps(const LiveInterval& other) const {
return overlapsFrom(other, other.begin());
}
/// overlaps - Return true if the live interval overlaps a range specified
/// by [Start, End).
bool overlaps(unsigned Start, unsigned 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(unsigned Start, unsigned End);
/// removeRange - Remove the specified range from this interval. Note that
/// the range must be a single LiveRange in its entirety.
void removeRange(unsigned Start, unsigned 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);
/// scaleNumbering - Renumber VNI and ranges to provide gaps for new
/// instructions.
void scaleNumbering(unsigned factor);
/// getSize - Returns the sum of sizes of all the LiveRange's.
///
unsigned getSize() const;
bool operator<(const LiveInterval& other) const {
return beginNumber() < other.beginNumber();
}
void print(std::ostream &OS, const TargetRegisterInfo *TRI = 0) const;
void print(std::ostream *OS, const TargetRegisterInfo *TRI = 0) const {
if (OS) print(*OS, TRI);
}
void dump() const;
private:
Ranges::iterator addRangeFrom(LiveRange LR, Ranges::iterator From);
void extendIntervalEndTo(Ranges::iterator I, unsigned NewEnd);
Ranges::iterator extendIntervalStartTo(Ranges::iterator I, unsigned NewStr);
LiveInterval& operator=(const LiveInterval& rhs); // DO NOT IMPLEMENT
};
inline std::ostream &operator<<(std::ostream &OS, const LiveInterval &LI) {
LI.print(OS);
return OS;
}
}
#endif