diff options
Diffstat (limited to 'contrib/llvm/lib/CodeGen/LiveInterval.cpp')
| -rw-r--r-- | contrib/llvm/lib/CodeGen/LiveInterval.cpp | 372 |
1 files changed, 220 insertions, 152 deletions
diff --git a/contrib/llvm/lib/CodeGen/LiveInterval.cpp b/contrib/llvm/lib/CodeGen/LiveInterval.cpp index 8585cbb..dccd847 100644 --- a/contrib/llvm/lib/CodeGen/LiveInterval.cpp +++ b/contrib/llvm/lib/CodeGen/LiveInterval.cpp @@ -19,15 +19,15 @@ //===----------------------------------------------------------------------===// #include "llvm/CodeGen/LiveInterval.h" -#include "llvm/CodeGen/LiveIntervalAnalysis.h" -#include "llvm/CodeGen/MachineRegisterInfo.h" +#include "RegisterCoalescer.h" #include "llvm/ADT/DenseMap.h" -#include "llvm/ADT/SmallSet.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 "RegisterCoalescer.h" #include <algorithm> using namespace llvm; @@ -440,7 +440,7 @@ void LiveInterval::join(LiveInterval &Other, iterator OutIt = begin(); OutIt->valno = NewVNInfo[LHSValNoAssignments[OutIt->valno->id]]; - for (iterator I = next(OutIt), E = end(); I != E; ++I) { + for (iterator I = llvm::next(OutIt), E = end(); I != E; ++I) { VNInfo* nextValNo = NewVNInfo[LHSValNoAssignments[I->valno->id]]; assert(nextValNo != 0 && "Huh?"); @@ -464,10 +464,12 @@ void LiveInterval::join(LiveInterval &Other, ranges.erase(OutIt, end()); } - // Remember assignements because val# ids are changing. - SmallVector<unsigned, 16> OtherAssignments; + // 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) - OtherAssignments.push_back(RHSValNoAssignments[I->valno->id]); + 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. @@ -486,148 +488,9 @@ void LiveInterval::join(LiveInterval &Other, valnos.resize(NumNewVals); // shrinkify // Okay, now insert the RHS live ranges into the LHS. - unsigned RangeNo = 0; - for (iterator I = Other.begin(), E = Other.end(); I != E; ++I, ++RangeNo) { - // Map the valno in the other live range to the current live range. - I->valno = NewVNInfo[OtherAssignments[RangeNo]]; - assert(I->valno && "Adding a dead range?"); - } - mergeIntervalRanges(Other); - - verify(); -} - -/// \brief Helper function for merging in another LiveInterval's ranges. -/// -/// This is a helper routine implementing an efficient merge of another -/// LiveIntervals ranges into the current interval. -/// -/// \param LHSValNo If non-NULL, set as the new value number for every range -/// from RHS which is merged into the LHS. -/// \param RHSValNo If non-NULL, then only ranges in RHS whose original value -/// number maches this value number will be merged into LHS. -void LiveInterval::mergeIntervalRanges(const LiveInterval &RHS, - VNInfo *LHSValNo, - const VNInfo *RHSValNo) { - if (RHS.empty()) - return; - - // Ensure we're starting with a valid range. Note that we don't verify RHS - // because it may have had its value numbers adjusted in preparation for - // merging. - verify(); - - // The strategy for merging these efficiently is as follows: - // - // 1) Find the beginning of the impacted ranges in the LHS. - // 2) Create a new, merged sub-squence of ranges merging from the position in - // #1 until either LHS or RHS is exhausted. Any part of LHS between RHS - // entries being merged will be copied into this new range. - // 3) Replace the relevant section in LHS with these newly merged ranges. - // 4) Append any remaning ranges from RHS if LHS is exhausted in #2. - // - // We don't follow the typical in-place merge strategy for sorted ranges of - // appending the new ranges to the back and then using std::inplace_merge - // because one step of the merge can both mutate the original elements and - // remove elements from the original. Essentially, because the merge includes - // collapsing overlapping ranges, a more complex approach is required. - - // We do an initial binary search to optimize for a common pattern: a large - // LHS, and a very small RHS. - const_iterator RI = RHS.begin(), RE = RHS.end(); - iterator LE = end(), LI = std::upper_bound(begin(), LE, *RI); - - // Merge into NewRanges until one of the ranges is exhausted. - SmallVector<LiveRange, 4> NewRanges; - - // Keep track of where to begin the replacement. - iterator ReplaceI = LI; - - // If there are preceding ranges in the LHS, put the last one into NewRanges - // so we can optionally extend it. Adjust the replacement point accordingly. - if (LI != begin()) { - ReplaceI = llvm::prior(LI); - NewRanges.push_back(*ReplaceI); - } - - // Now loop over the mergable portions of both LHS and RHS, merging into - // NewRanges. - while (LI != LE && RI != RE) { - // Skip incoming ranges with the wrong value. - if (RHSValNo && RI->valno != RHSValNo) { - ++RI; - continue; - } - - // Select the first range. We pick the earliest start point, and then the - // largest range. - LiveRange R = *LI; - if (*RI < R) { - R = *RI; - ++RI; - if (LHSValNo) - R.valno = LHSValNo; - } else { - ++LI; - } - - if (NewRanges.empty()) { - NewRanges.push_back(R); - continue; - } - - LiveRange &LastR = NewRanges.back(); - if (R.valno == LastR.valno) { - // Try to merge this range into the last one. - if (R.start <= LastR.end) { - LastR.end = std::max(LastR.end, R.end); - continue; - } - } else { - // We can't merge ranges across a value number. - assert(R.start >= LastR.end && - "Cannot overlap two LiveRanges with differing ValID's"); - } - - // If all else fails, just append the range. - NewRanges.push_back(R); - } - assert(RI == RE || LI == LE); - - // Check for being able to merge into the trailing sequence of ranges on the LHS. - if (!NewRanges.empty()) - for (; LI != LE && (LI->valno == NewRanges.back().valno && - LI->start <= NewRanges.back().end); - ++LI) - NewRanges.back().end = std::max(NewRanges.back().end, LI->end); - - // Replace the ranges in the LHS with the newly merged ones. It would be - // really nice if there were a move-supporting 'replace' directly in - // SmallVector, but as there is not, we pay the price of copies to avoid - // wasted memory allocations. - SmallVectorImpl<LiveRange>::iterator NRI = NewRanges.begin(), - NRE = NewRanges.end(); - for (; ReplaceI != LI && NRI != NRE; ++ReplaceI, ++NRI) - *ReplaceI = *NRI; - if (NRI == NRE) - ranges.erase(ReplaceI, LI); - else - ranges.insert(LI, NRI, NRE); - - // And finally insert any trailing end of RHS (if we have one). - for (; RI != RE; ++RI) { - LiveRange R = *RI; - if (LHSValNo) - R.valno = LHSValNo; - if (!ranges.empty() && - ranges.back().valno == R.valno && R.start <= ranges.back().end) - ranges.back().end = std::max(ranges.back().end, R.end); - else - ranges.push_back(R); - } - - // Ensure we finished with a valid new sequence of ranges. - verify(); + 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 @@ -636,7 +499,9 @@ void LiveInterval::mergeIntervalRanges(const LiveInterval &RHS, /// the overlapping LiveRanges have the specified value number. void LiveInterval::MergeRangesInAsValue(const LiveInterval &RHS, VNInfo *LHSValNo) { - mergeIntervalRanges(RHS, 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# @@ -647,7 +512,10 @@ void LiveInterval::MergeRangesInAsValue(const LiveInterval &RHS, void LiveInterval::MergeValueInAsValue(const LiveInterval &RHS, const VNInfo *RHSValNo, VNInfo *LHSValNo) { - mergeIntervalRanges(RHS, LHSValNo, RHSValNo); + 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 @@ -785,6 +653,206 @@ 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(); |
