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+//===-- LiveInterval.cpp - Live Interval Representation -------------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file was developed by the LLVM research group and 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' abd 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 "llvm/ADT/STLExtras.h"
+#include "llvm/Target/MRegisterInfo.h"
+#include <algorithm>
+#include <iostream>
+#include <map>
+using namespace llvm;
+
+// An example for liveAt():
+//
+// this = [1,4), liveAt(0) will return false. The instruction defining this
+// spans slots [0,3]. The interval belongs to an spilled definition of the
+// variable it represents. This is because slot 1 is used (def slot) and spans
+// up to slot 3 (store slot).
+//
+bool LiveInterval::liveAt(unsigned I) const {
+ Ranges::const_iterator r = std::upper_bound(ranges.begin(), ranges.end(), I);
+
+ if (r == ranges.begin())
+ return false;
+
+ --r;
+ return r->contains(I);
+}
+
+// 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 {
+ 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;
+}
+
+/// NontrivialOverlap - Check to see if the two live ranges specified by i and j
+/// overlap. If so, check to see if they have value numbers that are not
+/// iIdx/jIdx respectively. If both conditions are true, return true.
+static inline bool NontrivialOverlap(const LiveRange &I, const LiveRange &J,
+ unsigned iIdx, unsigned jIdx) {
+ if (I.start == J.start) {
+ // If this is not the allowed value merge, we cannot join.
+ if (I.ValId != iIdx || J.ValId != jIdx)
+ return true;
+ } else if (I.start < J.start) {
+ if (I.end > J.start && (I.ValId != iIdx || J.ValId != jIdx)) {
+ return true;
+ }
+ } else {
+ if (J.end > I.start && (I.ValId != iIdx || J.ValId != jIdx))
+ return true;
+ }
+
+ return false;
+}
+
+/// joinable - Two intervals are joinable if the either don't overlap at all
+/// or if the destination of the copy is a single assignment value, and it
+/// only overlaps with one value in the source interval.
+bool LiveInterval::joinable(const LiveInterval &other, unsigned CopyIdx) const {
+ const LiveRange *SourceLR = other.getLiveRangeContaining(CopyIdx-1);
+ const LiveRange *DestLR = getLiveRangeContaining(CopyIdx);
+ assert(SourceLR && DestLR && "Not joining due to a copy?");
+ unsigned OtherValIdx = SourceLR->ValId;
+ unsigned ThisValIdx = DestLR->ValId;
+
+ Ranges::const_iterator i = ranges.begin();
+ Ranges::const_iterator ie = ranges.end();
+ Ranges::const_iterator j = other.ranges.begin();
+ Ranges::const_iterator je = other.ranges.end();
+
+ if (i->start < j->start) {
+ i = std::upper_bound(i, ie, j->start);
+ if (i != ranges.begin()) --i;
+ } else if (j->start < i->start) {
+ j = std::upper_bound(j, je, i->start);
+ if (j != other.ranges.begin()) --j;
+ }
+
+ while (i != ie && j != je) {
+ if (NontrivialOverlap(*i, *j, ThisValIdx, OtherValIdx))
+ return false;
+
+ if (i->end < j->end)
+ ++i;
+ else
+ ++j;
+ }
+
+ return true;
+}
+
+/// getOverlapingRanges - Given another live interval which is defined as a
+/// copy from this one, return a list of all of the live ranges where the
+/// two overlap and have different value numbers.
+void LiveInterval::getOverlapingRanges(const LiveInterval &other,
+ unsigned CopyIdx,
+ std::vector<LiveRange*> &Ranges) {
+ const LiveRange *SourceLR = getLiveRangeContaining(CopyIdx-1);
+ const LiveRange *DestLR = other.getLiveRangeContaining(CopyIdx);
+ assert(SourceLR && DestLR && "Not joining due to a copy?");
+ unsigned OtherValIdx = SourceLR->ValId;
+ unsigned ThisValIdx = DestLR->ValId;
+
+ Ranges::iterator i = ranges.begin();
+ Ranges::iterator ie = ranges.end();
+ Ranges::const_iterator j = other.ranges.begin();
+ Ranges::const_iterator je = other.ranges.end();
+
+ if (i->start < j->start) {
+ i = std::upper_bound(i, ie, j->start);
+ if (i != ranges.begin()) --i;
+ } else if (j->start < i->start) {
+ j = std::upper_bound(j, je, i->start);
+ if (j != other.ranges.begin()) --j;
+ }
+
+ while (i != ie && j != je) {
+ if (NontrivialOverlap(*i, *j, ThisValIdx, OtherValIdx))
+ Ranges.push_back(&*i);
+
+ if (i->end < j->end)
+ ++i;
+ else
+ ++j;
+ }
+}
+
+
+
+/// 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, unsigned NewEnd) {
+ assert(I != ranges.end() && "Not a valid interval!");
+ unsigned ValId = I->ValId;
+
+ // Search for the first interval that we can't merge with.
+ Ranges::iterator MergeTo = next(I);
+ for (; MergeTo != ranges.end() && NewEnd >= MergeTo->end; ++MergeTo) {
+ assert(MergeTo->ValId == ValId && "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);
+
+ // Erase any dead ranges.
+ ranges.erase(next(I), MergeTo);
+
+ // 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.
+ Ranges::iterator Next = next(I);
+ if (Next != ranges.end() && Next->start <= I->end && Next->ValId == ValId) {
+ I->end = Next->end;
+ ranges.erase(Next);
+ }
+}
+
+
+/// 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, unsigned NewStart) {
+ assert(I != ranges.end() && "Not a valid interval!");
+ unsigned ValId = I->ValId;
+
+ // 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->ValId == ValId && "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->ValId == ValId) {
+ MergeTo->end = I->end;
+ } else {
+ // Otherwise, extend the interval right after.
+ ++MergeTo;
+ MergeTo->start = NewStart;
+ MergeTo->end = I->end;
+ }
+
+ ranges.erase(next(MergeTo), next(I));
+ return MergeTo;
+}
+
+LiveInterval::Ranges::iterator
+LiveInterval::addRangeFrom(LiveRange LR, Ranges::iterator From) {
+ unsigned Start = LR.start, End = LR.end;
+ Ranges::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()) {
+ Ranges::iterator B = prior(it);
+ if (LR.ValId == B->ValId) {
+ 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 ValId'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.ValId == it->ValId) {
+ 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 ValId'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);
+}
+
+
+/// removeRange - Remove the specified range from this interval. Note that
+/// the range must already be in this interval in its entirety.
+void LiveInterval::removeRange(unsigned Start, unsigned End) {
+ // Find the LiveRange containing this span.
+ Ranges::iterator I = std::upper_bound(ranges.begin(), ranges.end(), Start);
+ assert(I != ranges.begin() && "Range is not in interval!");
+ --I;
+ assert(I->contains(Start) && I->contains(End-1) &&
+ "Range is not entirely in interval!");
+
+ // If the span we are removing is at the start of the LiveRange, adjust it.
+ if (I->start == Start) {
+ if (I->end == End)
+ 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.
+ unsigned OldEnd = I->end;
+ I->end = Start; // Trim the old interval.
+
+ // Insert the new one.
+ ranges.insert(next(I), LiveRange(End, OldEnd, I->ValId));
+}
+
+/// getLiveRangeContaining - Return the live range that contains the
+/// specified index, or null if there is none.
+const LiveRange *LiveInterval::getLiveRangeContaining(unsigned Idx) const {
+ Ranges::const_iterator It = std::upper_bound(ranges.begin(),ranges.end(),Idx);
+ if (It != ranges.begin()) {
+ const LiveRange &LR = *prior(It);
+ if (LR.contains(Idx))
+ return &LR;
+ }
+
+ return 0;
+}
+
+
+
+/// join - Join two live intervals (this, and other) together. This operation
+/// is the result of a copy instruction in the source program, that occurs at
+/// index 'CopyIdx' that copies from 'Other' to 'this'.
+void LiveInterval::join(LiveInterval &Other, unsigned CopyIdx) {
+ const LiveRange *SourceLR = Other.getLiveRangeContaining(CopyIdx-1);
+ const LiveRange *DestLR = getLiveRangeContaining(CopyIdx);
+ assert(SourceLR && DestLR && "Not joining due to a copy?");
+ unsigned MergedSrcValIdx = SourceLR->ValId;
+ unsigned MergedDstValIdx = DestLR->ValId;
+
+ // Try to do the least amount of work possible. In particular, if there are
+ // more liverange chunks in the other set than there are in the 'this' set,
+ // swap sets to merge the fewest chunks in possible.
+ if (Other.ranges.size() > ranges.size()) {
+ std::swap(MergedSrcValIdx, MergedDstValIdx);
+ std::swap(ranges, Other.ranges);
+ std::swap(NumValues, Other.NumValues);
+ }
+
+ // Join the ranges of other into the ranges of this interval.
+ Ranges::iterator InsertPos = ranges.begin();
+ std::map<unsigned, unsigned> Dst2SrcIdxMap;
+ for (Ranges::iterator I = Other.ranges.begin(),
+ E = Other.ranges.end(); I != E; ++I) {
+ // Map the ValId in the other live range to the current live range.
+ if (I->ValId == MergedSrcValIdx)
+ I->ValId = MergedDstValIdx;
+ else {
+ unsigned &NV = Dst2SrcIdxMap[I->ValId];
+ if (NV == 0) NV = getNextValue();
+ I->ValId = NV;
+ }
+
+ InsertPos = addRangeFrom(*I, InsertPos);
+ }
+
+ weight += Other.weight;
+}
+
+std::ostream& llvm::operator<<(std::ostream& os, const LiveRange &LR) {
+ return os << '[' << LR.start << ',' << LR.end << ':' << LR.ValId << ")";
+}
+
+void LiveRange::dump() const {
+ std::cerr << *this << "\n";
+}
+
+void LiveInterval::print(std::ostream &OS, const MRegisterInfo *MRI) const {
+ if (MRI && MRegisterInfo::isPhysicalRegister(reg))
+ OS << MRI->getName(reg);
+ else
+ OS << "%reg" << reg;
+
+ OS << ',' << weight;
+
+ if (empty())
+ OS << "EMPTY";
+ else {
+ OS << " = ";
+ for (LiveInterval::Ranges::const_iterator I = ranges.begin(),
+ E = ranges.end(); I != E; ++I)
+ OS << *I;
+ }
+}
+
+void LiveInterval::dump() const {
+ std::cerr << *this << "\n";
+}
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