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Diffstat (limited to 'contrib/llvm/lib/CodeGen/LiveInterval.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/LiveInterval.cpp | 951 |
1 files changed, 951 insertions, 0 deletions
diff --git a/contrib/llvm/lib/CodeGen/LiveInterval.cpp b/contrib/llvm/lib/CodeGen/LiveInterval.cpp new file mode 100644 index 0000000..dccd847 --- /dev/null +++ b/contrib/llvm/lib/CodeGen/LiveInterval.cpp @@ -0,0 +1,951 @@ +//===-- LiveInterval.cpp - Live Interval Representation -------------------===// +// +// 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. +// +//===----------------------------------------------------------------------===// + +#include "llvm/CodeGen/LiveInterval.h" +#include "RegisterCoalescer.h" +#include "llvm/ADT/DenseMap.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/ADT/SmallSet.h" +#include "llvm/CodeGen/LiveIntervalAnalysis.h" +#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/raw_ostream.h" +#include "llvm/Target/TargetRegisterInfo.h" +#include <algorithm> +using namespace llvm; + +LiveInterval::iterator LiveInterval::find(SlotIndex Pos) { + // This algorithm is basically std::upper_bound. + // Unfortunately, std::upper_bound cannot be used with mixed types until we + // adopt C++0x. Many libraries can do it, but not all. + if (empty() || Pos >= endIndex()) + return end(); + iterator I = begin(); + size_t Len = ranges.size(); + do { + size_t Mid = Len >> 1; + if (Pos < I[Mid].end) + Len = Mid; + else + I += Mid + 1, Len -= Mid + 1; + } while (Len); + return I; +} + +VNInfo *LiveInterval::createDeadDef(SlotIndex Def, + VNInfo::Allocator &VNInfoAllocator) { + assert(!Def.isDead() && "Cannot define a value at the dead slot"); + iterator I = find(Def); + if (I == end()) { + VNInfo *VNI = getNextValue(Def, VNInfoAllocator); + ranges.push_back(LiveRange(Def, Def.getDeadSlot(), VNI)); + return VNI; + } + if (SlotIndex::isSameInstr(Def, I->start)) { + assert(I->valno->def == I->start && "Inconsistent existing value def"); + + // It is possible to have both normal and early-clobber defs of the same + // register on an instruction. It doesn't make a lot of sense, but it is + // possible to specify in inline assembly. + // + // Just convert everything to early-clobber. + Def = std::min(Def, I->start); + if (Def != I->start) + I->start = I->valno->def = Def; + return I->valno; + } + assert(SlotIndex::isEarlierInstr(Def, I->start) && "Already live at def"); + VNInfo *VNI = getNextValue(Def, VNInfoAllocator); + ranges.insert(I, LiveRange(Def, Def.getDeadSlot(), VNI)); + return VNI; +} + +// overlaps - Return true if the intersection of the two live intervals is +// not empty. +// +// An example for overlaps(): +// +// 0: A = ... +// 4: B = ... +// 8: C = A + B ;; last use of A +// +// The live intervals should look like: +// +// A = [3, 11) +// B = [7, x) +// C = [11, y) +// +// A->overlaps(C) should return false since we want to be able to join +// A and C. +// +bool LiveInterval::overlapsFrom(const LiveInterval& other, + const_iterator StartPos) const { + assert(!empty() && "empty interval"); + const_iterator i = begin(); + const_iterator ie = end(); + const_iterator j = StartPos; + const_iterator je = other.end(); + + assert((StartPos->start <= i->start || StartPos == other.begin()) && + StartPos != other.end() && "Bogus start position hint!"); + + if (i->start < j->start) { + i = std::upper_bound(i, ie, j->start); + if (i != ranges.begin()) --i; + } else if (j->start < i->start) { + ++StartPos; + if (StartPos != other.end() && StartPos->start <= i->start) { + assert(StartPos < other.end() && i < end()); + j = std::upper_bound(j, je, i->start); + if (j != other.ranges.begin()) --j; + } + } else { + return true; + } + + if (j == je) return false; + + while (i != ie) { + if (i->start > j->start) { + std::swap(i, j); + std::swap(ie, je); + } + + if (i->end > j->start) + return true; + ++i; + } + + return false; +} + +bool LiveInterval::overlaps(const LiveInterval &Other, + const CoalescerPair &CP, + const SlotIndexes &Indexes) const { + assert(!empty() && "empty interval"); + if (Other.empty()) + return false; + + // Use binary searches to find initial positions. + const_iterator I = find(Other.beginIndex()); + const_iterator IE = end(); + if (I == IE) + return false; + const_iterator J = Other.find(I->start); + const_iterator JE = Other.end(); + if (J == JE) + return false; + + for (;;) { + // J has just been advanced to satisfy: + assert(J->end >= I->start); + // Check for an overlap. + if (J->start < I->end) { + // I and J are overlapping. Find the later start. + SlotIndex Def = std::max(I->start, J->start); + // Allow the overlap if Def is a coalescable copy. + if (Def.isBlock() || + !CP.isCoalescable(Indexes.getInstructionFromIndex(Def))) + return true; + } + // Advance the iterator that ends first to check for more overlaps. + if (J->end > I->end) { + std::swap(I, J); + std::swap(IE, JE); + } + // Advance J until J->end >= I->start. + do + if (++J == JE) + return false; + while (J->end < I->start); + } +} + +/// overlaps - Return true if the live interval overlaps a range specified +/// by [Start, End). +bool LiveInterval::overlaps(SlotIndex Start, SlotIndex End) const { + assert(Start < End && "Invalid range"); + const_iterator I = std::lower_bound(begin(), end(), End); + return I != begin() && (--I)->end > Start; +} + + +/// ValNo is dead, remove it. If it is the largest value number, just nuke it +/// (and any other deleted values neighboring it), otherwise mark it as ~1U so +/// it can be nuked later. +void LiveInterval::markValNoForDeletion(VNInfo *ValNo) { + if (ValNo->id == getNumValNums()-1) { + do { + valnos.pop_back(); + } while (!valnos.empty() && valnos.back()->isUnused()); + } else { + ValNo->markUnused(); + } +} + +/// RenumberValues - Renumber all values in order of appearance and delete the +/// remaining unused values. +void LiveInterval::RenumberValues(LiveIntervals &lis) { + SmallPtrSet<VNInfo*, 8> Seen; + valnos.clear(); + for (const_iterator I = begin(), E = end(); I != E; ++I) { + VNInfo *VNI = I->valno; + if (!Seen.insert(VNI)) + continue; + assert(!VNI->isUnused() && "Unused valno used by live range"); + VNI->id = (unsigned)valnos.size(); + valnos.push_back(VNI); + } +} + +/// extendIntervalEndTo - This method is used when we want to extend the range +/// specified by I to end at the specified endpoint. To do this, we should +/// merge and eliminate all ranges that this will overlap with. The iterator is +/// not invalidated. +void LiveInterval::extendIntervalEndTo(Ranges::iterator I, SlotIndex NewEnd) { + assert(I != ranges.end() && "Not a valid interval!"); + VNInfo *ValNo = I->valno; + + // Search for the first interval that we can't merge with. + Ranges::iterator MergeTo = llvm::next(I); + for (; MergeTo != ranges.end() && NewEnd >= MergeTo->end; ++MergeTo) { + assert(MergeTo->valno == ValNo && "Cannot merge with differing values!"); + } + + // If NewEnd was in the middle of an interval, make sure to get its endpoint. + I->end = std::max(NewEnd, prior(MergeTo)->end); + + // If the newly formed range now touches the range after it and if they have + // the same value number, merge the two ranges into one range. + if (MergeTo != ranges.end() && MergeTo->start <= I->end && + MergeTo->valno == ValNo) { + I->end = MergeTo->end; + ++MergeTo; + } + + // Erase any dead ranges. + ranges.erase(llvm::next(I), MergeTo); +} + + +/// extendIntervalStartTo - This method is used when we want to extend the range +/// specified by I to start at the specified endpoint. To do this, we should +/// merge and eliminate all ranges that this will overlap with. +LiveInterval::Ranges::iterator +LiveInterval::extendIntervalStartTo(Ranges::iterator I, SlotIndex NewStart) { + assert(I != ranges.end() && "Not a valid interval!"); + VNInfo *ValNo = I->valno; + + // Search for the first interval that we can't merge with. + Ranges::iterator MergeTo = I; + do { + if (MergeTo == ranges.begin()) { + I->start = NewStart; + ranges.erase(MergeTo, I); + return I; + } + assert(MergeTo->valno == ValNo && "Cannot merge with differing values!"); + --MergeTo; + } while (NewStart <= MergeTo->start); + + // If we start in the middle of another interval, just delete a range and + // extend that interval. + if (MergeTo->end >= NewStart && MergeTo->valno == ValNo) { + MergeTo->end = I->end; + } else { + // Otherwise, extend the interval right after. + ++MergeTo; + MergeTo->start = NewStart; + MergeTo->end = I->end; + } + + ranges.erase(llvm::next(MergeTo), llvm::next(I)); + return MergeTo; +} + +LiveInterval::iterator +LiveInterval::addRangeFrom(LiveRange LR, iterator From) { + SlotIndex Start = LR.start, End = LR.end; + iterator it = std::upper_bound(From, ranges.end(), Start); + + // If the inserted interval starts in the middle or right at the end of + // another interval, just extend that interval to contain the range of LR. + if (it != ranges.begin()) { + iterator B = prior(it); + if (LR.valno == B->valno) { + if (B->start <= Start && B->end >= Start) { + extendIntervalEndTo(B, End); + return B; + } + } else { + // Check to make sure that we are not overlapping two live ranges with + // different valno's. + assert(B->end <= Start && + "Cannot overlap two LiveRanges with differing ValID's" + " (did you def the same reg twice in a MachineInstr?)"); + } + } + + // Otherwise, if this range ends in the middle of, or right next to, another + // interval, merge it into that interval. + if (it != ranges.end()) { + if (LR.valno == it->valno) { + if (it->start <= End) { + it = extendIntervalStartTo(it, Start); + + // If LR is a complete superset of an interval, we may need to grow its + // endpoint as well. + if (End > it->end) + extendIntervalEndTo(it, End); + return it; + } + } else { + // Check to make sure that we are not overlapping two live ranges with + // different valno's. + assert(it->start >= End && + "Cannot overlap two LiveRanges with differing ValID's"); + } + } + + // Otherwise, this is just a new range that doesn't interact with anything. + // Insert it. + return ranges.insert(it, LR); +} + +/// 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 *LiveInterval::extendInBlock(SlotIndex StartIdx, SlotIndex Kill) { + if (empty()) + return 0; + iterator I = std::upper_bound(begin(), end(), Kill.getPrevSlot()); + if (I == begin()) + return 0; + --I; + if (I->end <= StartIdx) + return 0; + if (I->end < Kill) + extendIntervalEndTo(I, Kill); + return I->valno; +} + +/// removeRange - Remove the specified range from this interval. Note that +/// the range must be in a single LiveRange in its entirety. +void LiveInterval::removeRange(SlotIndex Start, SlotIndex End, + bool RemoveDeadValNo) { + // Find the LiveRange containing this span. + Ranges::iterator I = find(Start); + assert(I != ranges.end() && "Range is not in interval!"); + assert(I->containsRange(Start, End) && "Range is not entirely in interval!"); + + // If the span we are removing is at the start of the LiveRange, adjust it. + VNInfo *ValNo = I->valno; + if (I->start == Start) { + if (I->end == End) { + if (RemoveDeadValNo) { + // Check if val# is dead. + bool isDead = true; + for (const_iterator II = begin(), EE = end(); II != EE; ++II) + if (II != I && II->valno == ValNo) { + isDead = false; + break; + } + if (isDead) { + // Now that ValNo is dead, remove it. + markValNoForDeletion(ValNo); + } + } + + ranges.erase(I); // Removed the whole LiveRange. + } else + I->start = End; + return; + } + + // Otherwise if the span we are removing is at the end of the LiveRange, + // adjust the other way. + if (I->end == End) { + I->end = Start; + return; + } + + // Otherwise, we are splitting the LiveRange into two pieces. + SlotIndex OldEnd = I->end; + I->end = Start; // Trim the old interval. + + // Insert the new one. + ranges.insert(llvm::next(I), LiveRange(End, OldEnd, ValNo)); +} + +/// removeValNo - Remove all the ranges defined by the specified value#. +/// Also remove the value# from value# list. +void LiveInterval::removeValNo(VNInfo *ValNo) { + if (empty()) return; + Ranges::iterator I = ranges.end(); + Ranges::iterator E = ranges.begin(); + do { + --I; + if (I->valno == ValNo) + ranges.erase(I); + } while (I != E); + // Now that ValNo is dead, remove it. + markValNoForDeletion(ValNo); +} + +/// 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 LiveInterval::join(LiveInterval &Other, + const int *LHSValNoAssignments, + const int *RHSValNoAssignments, + SmallVector<VNInfo*, 16> &NewVNInfo, + MachineRegisterInfo *MRI) { + verify(); + + // Determine if any of our live range values are mapped. This is uncommon, so + // we want to avoid the interval scan if not. + bool MustMapCurValNos = false; + unsigned NumVals = getNumValNums(); + unsigned NumNewVals = NewVNInfo.size(); + for (unsigned i = 0; i != NumVals; ++i) { + unsigned LHSValID = LHSValNoAssignments[i]; + if (i != LHSValID || + (NewVNInfo[LHSValID] && NewVNInfo[LHSValID] != getValNumInfo(i))) { + MustMapCurValNos = true; + break; + } + } + + // If we have to apply a mapping to our base interval assignment, rewrite it + // now. + if (MustMapCurValNos && !empty()) { + // Map the first live range. + + iterator OutIt = begin(); + OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]]; + for (iterator I = llvm::next(OutIt), E = end(); I != E; ++I) { + VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]]; + assert(nextValNo != 0 && "Huh?"); + + // If this live range has the same value # as its immediate predecessor, + // and if they are neighbors, remove one LiveRange. This happens when we + // have [0,4:0)[4,7:1) and map 0/1 onto the same value #. + if (OutIt->valno == nextValNo && OutIt->end == I->start) { + OutIt->end = I->end; + } else { + // Didn't merge. Move OutIt to the next interval, + ++OutIt; + OutIt->valno = nextValNo; + if (OutIt != I) { + OutIt->start = I->start; + OutIt->end = I->end; + } + } + } + // If we merge some live ranges, chop off the end. + ++OutIt; + ranges.erase(OutIt, end()); + } + + // Rewrite Other values before changing the VNInfo ids. + // This can leave Other in an invalid state because we're not coalescing + // touching segments that now have identical values. That's OK since Other is + // not supposed to be valid after calling join(); + for (iterator I = Other.begin(), E = Other.end(); I != E; ++I) + I->valno = NewVNInfo[RHSValNoAssignments[I->valno->id]]; + + // Update val# info. Renumber them and make sure they all belong to this + // LiveInterval now. Also remove dead val#'s. + unsigned NumValNos = 0; + for (unsigned i = 0; i < NumNewVals; ++i) { + VNInfo *VNI = NewVNInfo[i]; + if (VNI) { + if (NumValNos >= NumVals) + valnos.push_back(VNI); + else + valnos[NumValNos] = VNI; + VNI->id = NumValNos++; // Renumber val#. + } + } + if (NumNewVals < NumVals) + valnos.resize(NumNewVals); // shrinkify + + // Okay, now insert the RHS live ranges into the LHS. + LiveRangeUpdater Updater(this); + for (iterator I = Other.begin(), E = Other.end(); I != E; ++I) + Updater.add(*I); +} + +/// MergeRangesInAsValue - Merge all of the intervals 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 LiveInterval::MergeRangesInAsValue(const LiveInterval &RHS, + VNInfo *LHSValNo) { + LiveRangeUpdater Updater(this); + for (const_iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) + Updater.add(I->start, I->end, 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, it will replace the value numbers of the overlaped +/// live ranges with the specified value number. +void LiveInterval::MergeValueInAsValue(const LiveInterval &RHS, + const VNInfo *RHSValNo, + VNInfo *LHSValNo) { + LiveRangeUpdater Updater(this); + for (const_iterator I = RHS.begin(), E = RHS.end(); I != E; ++I) + if (I->valno == RHSValNo) + Updater.add(I->start, I->end, LHSValNo); +} + +/// 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* LiveInterval::MergeValueNumberInto(VNInfo *V1, VNInfo *V2) { + assert(V1 != V2 && "Identical value#'s are always equivalent!"); + + // This code actually merges the (numerically) larger value number into the + // smaller value number, which is likely to allow us to compactify the value + // space. The only thing we have to be careful of is to preserve the + // instruction that defines the result value. + + // Make sure V2 is smaller than V1. + if (V1->id < V2->id) { + V1->copyFrom(*V2); + std::swap(V1, V2); + } + + // Merge V1 live ranges into V2. + for (iterator I = begin(); I != end(); ) { + iterator LR = I++; + if (LR->valno != V1) continue; // Not a V1 LiveRange. + + // Okay, we found a V1 live range. If it had a previous, touching, V2 live + // range, extend it. + if (LR != begin()) { + iterator Prev = LR-1; + if (Prev->valno == V2 && Prev->end == LR->start) { + Prev->end = LR->end; + + // Erase this live-range. + ranges.erase(LR); + I = Prev+1; + LR = Prev; + } + } + + // Okay, now we have a V1 or V2 live range that is maximally merged forward. + // Ensure that it is a V2 live-range. + LR->valno = V2; + + // If we can merge it into later V2 live ranges, do so now. We ignore any + // following V1 live ranges, as they will be merged in subsequent iterations + // of the loop. + if (I != end()) { + if (I->start == LR->end && I->valno == V2) { + LR->end = I->end; + ranges.erase(I); + I = LR+1; + } + } + } + + // Now that V1 is dead, remove it. + markValNoForDeletion(V1); + + return V2; +} + +unsigned LiveInterval::getSize() const { + unsigned Sum = 0; + for (const_iterator I = begin(), E = end(); I != E; ++I) + Sum += I->start.distance(I->end); + return Sum; +} + +raw_ostream& llvm::operator<<(raw_ostream& os, const LiveRange &LR) { + return os << '[' << LR.start << ',' << LR.end << ':' << LR.valno->id << ")"; +} + +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +void LiveRange::dump() const { + dbgs() << *this << "\n"; +} +#endif + +void LiveInterval::print(raw_ostream &OS) const { + if (empty()) + OS << "EMPTY"; + else { + for (LiveInterval::Ranges::const_iterator I = ranges.begin(), + E = ranges.end(); I != E; ++I) { + OS << *I; + assert(I->valno == getValNumInfo(I->valno->id) && "Bad VNInfo"); + } + } + + // Print value number info. + if (getNumValNums()) { + OS << " "; + unsigned vnum = 0; + for (const_vni_iterator i = vni_begin(), e = vni_end(); i != e; + ++i, ++vnum) { + const VNInfo *vni = *i; + if (vnum) OS << " "; + OS << vnum << "@"; + if (vni->isUnused()) { + OS << "x"; + } else { + OS << vni->def; + if (vni->isPHIDef()) + OS << "-phi"; + } + } + } +} + +#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) +void LiveInterval::dump() const { + dbgs() << *this << "\n"; +} +#endif + +#ifndef NDEBUG +void LiveInterval::verify() const { + for (const_iterator I = begin(), E = end(); I != E; ++I) { + assert(I->start.isValid()); + assert(I->end.isValid()); + assert(I->start < I->end); + assert(I->valno != 0); + assert(I->valno == valnos[I->valno->id]); + if (llvm::next(I) != E) { + assert(I->end <= llvm::next(I)->start); + if (I->end == llvm::next(I)->start) + assert(I->valno != llvm::next(I)->valno); + } + } +} +#endif + + +void LiveRange::print(raw_ostream &os) const { + os << *this; +} + +//===----------------------------------------------------------------------===// +// LiveRangeUpdater class +//===----------------------------------------------------------------------===// +// +// The LiveRangeUpdater class always maintains these invariants: +// +// - When LastStart is invalid, Spills is empty and the iterators are invalid. +// This is the initial state, and the state created by flush(). +// In this state, isDirty() returns false. +// +// Otherwise, segments are kept in three separate areas: +// +// 1. [begin; WriteI) at the front of LI. +// 2. [ReadI; end) at the back of LI. +// 3. Spills. +// +// - LI.begin() <= WriteI <= ReadI <= LI.end(). +// - Segments in all three areas are fully ordered and coalesced. +// - Segments in area 1 precede and can't coalesce with segments in area 2. +// - Segments in Spills precede and can't coalesce with segments in area 2. +// - No coalescing is possible between segments in Spills and segments in area +// 1, and there are no overlapping segments. +// +// The segments in Spills are not ordered with respect to the segments in area +// 1. They need to be merged. +// +// When they exist, Spills.back().start <= LastStart, +// and WriteI[-1].start <= LastStart. + +void LiveRangeUpdater::print(raw_ostream &OS) const { + if (!isDirty()) { + if (LI) + OS << "Clean " << PrintReg(LI->reg) << " updater: " << *LI << '\n'; + else + OS << "Null updater.\n"; + return; + } + assert(LI && "Can't have null LI in dirty updater."); + OS << PrintReg(LI->reg) << " updater with gap = " << (ReadI - WriteI) + << ", last start = " << LastStart + << ":\n Area 1:"; + for (LiveInterval::const_iterator I = LI->begin(); I != WriteI; ++I) + OS << ' ' << *I; + OS << "\n Spills:"; + for (unsigned I = 0, E = Spills.size(); I != E; ++I) + OS << ' ' << Spills[I]; + OS << "\n Area 2:"; + for (LiveInterval::const_iterator I = ReadI, E = LI->end(); I != E; ++I) + OS << ' ' << *I; + OS << '\n'; +} + +void LiveRangeUpdater::dump() const +{ + print(errs()); +} + +// Determine if A and B should be coalesced. +static inline bool coalescable(const LiveRange &A, const LiveRange &B) { + assert(A.start <= B.start && "Unordered live ranges."); + if (A.end == B.start) + return A.valno == B.valno; + if (A.end < B.start) + return false; + assert(A.valno == B.valno && "Cannot overlap different values"); + return true; +} + +void LiveRangeUpdater::add(LiveRange Seg) { + assert(LI && "Cannot add to a null destination"); + + // Flush the state if Start moves backwards. + if (!LastStart.isValid() || LastStart > Seg.start) { + if (isDirty()) + flush(); + // This brings us to an uninitialized state. Reinitialize. + assert(Spills.empty() && "Leftover spilled segments"); + WriteI = ReadI = LI->begin(); + } + + // Remember start for next time. + LastStart = Seg.start; + + // Advance ReadI until it ends after Seg.start. + LiveInterval::iterator E = LI->end(); + if (ReadI != E && ReadI->end <= Seg.start) { + // First try to close the gap between WriteI and ReadI with spills. + if (ReadI != WriteI) + mergeSpills(); + // Then advance ReadI. + if (ReadI == WriteI) + ReadI = WriteI = LI->find(Seg.start); + else + while (ReadI != E && ReadI->end <= Seg.start) + *WriteI++ = *ReadI++; + } + + assert(ReadI == E || ReadI->end > Seg.start); + + // Check if the ReadI segment begins early. + if (ReadI != E && ReadI->start <= Seg.start) { + assert(ReadI->valno == Seg.valno && "Cannot overlap different values"); + // Bail if Seg is completely contained in ReadI. + if (ReadI->end >= Seg.end) + return; + // Coalesce into Seg. + Seg.start = ReadI->start; + ++ReadI; + } + + // Coalesce as much as possible from ReadI into Seg. + while (ReadI != E && coalescable(Seg, *ReadI)) { + Seg.end = std::max(Seg.end, ReadI->end); + ++ReadI; + } + + // Try coalescing Spills.back() into Seg. + if (!Spills.empty() && coalescable(Spills.back(), Seg)) { + Seg.start = Spills.back().start; + Seg.end = std::max(Spills.back().end, Seg.end); + Spills.pop_back(); + } + + // Try coalescing Seg into WriteI[-1]. + if (WriteI != LI->begin() && coalescable(WriteI[-1], Seg)) { + WriteI[-1].end = std::max(WriteI[-1].end, Seg.end); + return; + } + + // Seg doesn't coalesce with anything, and needs to be inserted somewhere. + if (WriteI != ReadI) { + *WriteI++ = Seg; + return; + } + + // Finally, append to LI or Spills. + if (WriteI == E) { + LI->ranges.push_back(Seg); + WriteI = ReadI = LI->ranges.end(); + } else + Spills.push_back(Seg); +} + +// Merge as many spilled segments as possible into the gap between WriteI +// and ReadI. Advance WriteI to reflect the inserted instructions. +void LiveRangeUpdater::mergeSpills() { + // Perform a backwards merge of Spills and [SpillI;WriteI). + size_t GapSize = ReadI - WriteI; + size_t NumMoved = std::min(Spills.size(), GapSize); + LiveInterval::iterator Src = WriteI; + LiveInterval::iterator Dst = Src + NumMoved; + LiveInterval::iterator SpillSrc = Spills.end(); + LiveInterval::iterator B = LI->begin(); + + // This is the new WriteI position after merging spills. + WriteI = Dst; + + // Now merge Src and Spills backwards. + while (Src != Dst) { + if (Src != B && Src[-1].start > SpillSrc[-1].start) + *--Dst = *--Src; + else + *--Dst = *--SpillSrc; + } + assert(NumMoved == size_t(Spills.end() - SpillSrc)); + Spills.erase(SpillSrc, Spills.end()); +} + +void LiveRangeUpdater::flush() { + if (!isDirty()) + return; + // Clear the dirty state. + LastStart = SlotIndex(); + + assert(LI && "Cannot add to a null destination"); + + // Nothing to merge? + if (Spills.empty()) { + LI->ranges.erase(WriteI, ReadI); + LI->verify(); + return; + } + + // Resize the WriteI - ReadI gap to match Spills. + size_t GapSize = ReadI - WriteI; + if (GapSize < Spills.size()) { + // The gap is too small. Make some room. + size_t WritePos = WriteI - LI->begin(); + LI->ranges.insert(ReadI, Spills.size() - GapSize, LiveRange()); + // This also invalidated ReadI, but it is recomputed below. + WriteI = LI->ranges.begin() + WritePos; + } else { + // Shrink the gap if necessary. + LI->ranges.erase(WriteI + Spills.size(), ReadI); + } + ReadI = WriteI + Spills.size(); + mergeSpills(); + LI->verify(); +} + +unsigned ConnectedVNInfoEqClasses::Classify(const LiveInterval *LI) { + // Create initial equivalence classes. + EqClass.clear(); + EqClass.grow(LI->getNumValNums()); + + const VNInfo *used = 0, *unused = 0; + + // Determine connections. + for (LiveInterval::const_vni_iterator I = LI->vni_begin(), E = LI->vni_end(); + I != E; ++I) { + const VNInfo *VNI = *I; + // Group all unused values into one class. + if (VNI->isUnused()) { + if (unused) + EqClass.join(unused->id, VNI->id); + unused = VNI; + continue; + } + used = VNI; + if (VNI->isPHIDef()) { + const MachineBasicBlock *MBB = LIS.getMBBFromIndex(VNI->def); + assert(MBB && "Phi-def has no defining MBB"); + // Connect to values live out of predecessors. + for (MachineBasicBlock::const_pred_iterator PI = MBB->pred_begin(), + PE = MBB->pred_end(); PI != PE; ++PI) + if (const VNInfo *PVNI = LI->getVNInfoBefore(LIS.getMBBEndIdx(*PI))) + EqClass.join(VNI->id, PVNI->id); + } else { + // Normal value defined by an instruction. Check for two-addr redef. + // FIXME: This could be coincidental. Should we really check for a tied + // operand constraint? + // Note that VNI->def may be a use slot for an early clobber def. + if (const VNInfo *UVNI = LI->getVNInfoBefore(VNI->def)) + EqClass.join(VNI->id, UVNI->id); + } + } + + // Lump all the unused values in with the last used value. + if (used && unused) + EqClass.join(used->id, unused->id); + + EqClass.compress(); + return EqClass.getNumClasses(); +} + +void ConnectedVNInfoEqClasses::Distribute(LiveInterval *LIV[], + MachineRegisterInfo &MRI) { + assert(LIV[0] && "LIV[0] must be set"); + LiveInterval &LI = *LIV[0]; + + // Rewrite instructions. + for (MachineRegisterInfo::reg_iterator RI = MRI.reg_begin(LI.reg), + RE = MRI.reg_end(); RI != RE;) { + MachineOperand &MO = RI.getOperand(); + MachineInstr *MI = MO.getParent(); + ++RI; + // DBG_VALUE instructions should have been eliminated earlier. + LiveRangeQuery LRQ(LI, LIS.getInstructionIndex(MI)); + const VNInfo *VNI = MO.readsReg() ? LRQ.valueIn() : LRQ.valueDefined(); + // In the case of an <undef> use that isn't tied to any def, VNI will be + // NULL. If the use is tied to a def, VNI will be the defined value. + if (!VNI) + continue; + MO.setReg(LIV[getEqClass(VNI)]->reg); + } + + // Move runs to new intervals. + LiveInterval::iterator J = LI.begin(), E = LI.end(); + while (J != E && EqClass[J->valno->id] == 0) + ++J; + for (LiveInterval::iterator I = J; I != E; ++I) { + if (unsigned eq = EqClass[I->valno->id]) { + assert((LIV[eq]->empty() || LIV[eq]->expiredAt(I->start)) && + "New intervals should be empty"); + LIV[eq]->ranges.push_back(*I); + } else + *J++ = *I; + } + LI.ranges.erase(J, E); + + // Transfer VNInfos to their new owners and renumber them. + unsigned j = 0, e = LI.getNumValNums(); + while (j != e && EqClass[j] == 0) + ++j; + for (unsigned i = j; i != e; ++i) { + VNInfo *VNI = LI.getValNumInfo(i); + if (unsigned eq = EqClass[i]) { + VNI->id = LIV[eq]->getNumValNums(); + LIV[eq]->valnos.push_back(VNI); + } else { + VNI->id = j; + LI.valnos[j++] = VNI; + } + } + LI.valnos.resize(j); +} |
