//
//===----------------------------------------------------------------------===//
-#define DEBUG_TYPE "regalloc"
-#include "LiveIntervalUnion.h"
+#include "llvm/CodeGen/LiveIntervalUnion.h"
#include "llvm/ADT/SparseBitVector.h"
-#include "llvm/CodeGen/MachineLoopRanges.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetRegisterInfo.h"
+#include <algorithm>
using namespace llvm;
+#define DEBUG_TYPE "regalloc"
+
// Merge a LiveInterval's segments. Guarantee no overlaps.
-void LiveIntervalUnion::unify(LiveInterval &VirtReg) {
- if (VirtReg.empty())
+void LiveIntervalUnion::unify(LiveInterval &VirtReg, const LiveRange &Range) {
+ if (Range.empty())
return;
+ ++Tag;
// Insert each of the virtual register's live segments into the map.
- LiveInterval::iterator RegPos = VirtReg.begin();
- LiveInterval::iterator RegEnd = VirtReg.end();
+ LiveRange::const_iterator RegPos = Range.begin();
+ LiveRange::const_iterator RegEnd = Range.end();
SegmentIter SegPos = Segments.find(RegPos->start);
- for (;;) {
+ while (SegPos.valid()) {
SegPos.insert(RegPos->start, RegPos->end, &VirtReg);
if (++RegPos == RegEnd)
return;
SegPos.advanceTo(RegPos->start);
}
+
+ // We have reached the end of Segments, so it is no longer necessary to search
+ // for the insertion position.
+ // It is faster to insert the end first.
+ --RegEnd;
+ SegPos.insert(RegEnd->start, RegEnd->end, &VirtReg);
+ for (; RegPos != RegEnd; ++RegPos, ++SegPos)
+ SegPos.insert(RegPos->start, RegPos->end, &VirtReg);
}
// Remove a live virtual register's segments from this union.
-void LiveIntervalUnion::extract(LiveInterval &VirtReg) {
- if (VirtReg.empty())
+void LiveIntervalUnion::extract(LiveInterval &VirtReg, const LiveRange &Range) {
+ if (Range.empty())
return;
+ ++Tag;
// Remove each of the virtual register's live segments from the map.
- LiveInterval::iterator RegPos = VirtReg.begin();
- LiveInterval::iterator RegEnd = VirtReg.end();
+ LiveRange::const_iterator RegPos = Range.begin();
+ LiveRange::const_iterator RegEnd = Range.end();
SegmentIter SegPos = Segments.find(RegPos->start);
for (;;) {
return;
// Skip all segments that may have been coalesced.
- RegPos = VirtReg.advanceTo(RegPos, SegPos.start());
+ RegPos = Range.advanceTo(RegPos, SegPos.start());
if (RegPos == RegEnd)
return;
void
LiveIntervalUnion::print(raw_ostream &OS, const TargetRegisterInfo *TRI) const {
- OS << "LIU ";
- TRI->printReg(RepReg, OS);
if (empty()) {
OS << " empty\n";
return;
}
for (LiveSegments::const_iterator SI = Segments.begin(); SI.valid(); ++SI) {
- OS << " [" << SI.start() << ' ' << SI.stop() << "):";
- TRI->printReg(SI.value()->reg, OS);
+ OS << " [" << SI.start() << ' ' << SI.stop() << "):"
+ << PrintReg(SI.value()->reg, TRI);
}
OS << '\n';
}
-void LiveIntervalUnion::InterferenceResult::print(raw_ostream &OS,
- const TargetRegisterInfo *TRI) const {
- OS << '[' << start() << ';' << stop() << "):";
- TRI->printReg(interference()->reg, OS);
-}
-
-void LiveIntervalUnion::Query::print(raw_ostream &OS,
- const TargetRegisterInfo *TRI) {
- OS << "Interferences with ";
- LiveUnion->print(OS, TRI);
- InterferenceResult IR = firstInterference();
- while (isInterference(IR)) {
- OS << " ";
- IR.print(OS, TRI);
- OS << '\n';
- nextInterference(IR);
- }
-}
-
#ifndef NDEBUG
// Verify the live intervals in this union and add them to the visited set.
void LiveIntervalUnion::verify(LiveVirtRegBitSet& VisitedVRegs) {
}
#endif //!NDEBUG
-// Private interface accessed by Query.
-//
-// Find a pair of segments that intersect, one in the live virtual register
-// (LiveInterval), and the other in this LiveIntervalUnion. The caller (Query)
-// is responsible for advancing the LiveIntervalUnion segments to find a
-// "notable" intersection, which requires query-specific logic.
-//
-// This design assumes only a fast mechanism for intersecting a single live
-// virtual register segment with a set of LiveIntervalUnion segments. This may
-// be ok since most virtual registers have very few segments. If we had a data
-// structure that optimizd MxN intersection of segments, then we would bypass
-// the loop that advances within the LiveInterval.
-//
-// If no intersection exists, set VirtRegI = VirtRegEnd, and set SI to the first
-// segment whose start point is greater than LiveInterval's end point.
-//
-// Assumes that segments are sorted by start position in both
-// LiveInterval and LiveSegments.
-void LiveIntervalUnion::Query::findIntersection(InterferenceResult &IR) const {
- // Search until reaching the end of the LiveUnion segments.
- LiveInterval::iterator VirtRegEnd = VirtReg->end();
- if (IR.VirtRegI == VirtRegEnd)
- return;
- while (IR.LiveUnionI.valid()) {
- // Slowly advance the live virtual reg iterator until we surpass the next
- // segment in LiveUnion.
- //
- // Note: If this is ever used for coalescing of fixed registers and we have
- // a live vreg with thousands of segments, then change this code to use
- // upperBound instead.
- IR.VirtRegI = VirtReg->advanceTo(IR.VirtRegI, IR.LiveUnionI.start());
- if (IR.VirtRegI == VirtRegEnd)
- break; // Retain current (nonoverlapping) LiveUnionI
-
- // VirtRegI may have advanced far beyond LiveUnionI, catch up.
- IR.LiveUnionI.advanceTo(IR.VirtRegI->start);
-
- // Check if no LiveUnionI exists with VirtRegI->Start < LiveUnionI.end
- if (!IR.LiveUnionI.valid())
- break;
- if (IR.LiveUnionI.start() < IR.VirtRegI->end) {
- assert(overlap(*IR.VirtRegI, IR.LiveUnionI) &&
- "upperBound postcondition");
- break;
- }
- }
- if (!IR.LiveUnionI.valid())
- IR.VirtRegI = VirtRegEnd;
-}
-
-// Find the first intersection, and cache interference info
-// (retain segment iterators into both VirtReg and LiveUnion).
-const LiveIntervalUnion::InterferenceResult &
-LiveIntervalUnion::Query::firstInterference() {
- if (CheckedFirstInterference)
- return FirstInterference;
- CheckedFirstInterference = true;
- InterferenceResult &IR = FirstInterference;
-
- // Quickly skip interference check for empty sets.
- if (VirtReg->empty() || LiveUnion->empty()) {
- IR.VirtRegI = VirtReg->end();
- } else if (VirtReg->beginIndex() < LiveUnion->startIndex()) {
- // VirtReg starts first, perform double binary search.
- IR.VirtRegI = VirtReg->find(LiveUnion->startIndex());
- if (IR.VirtRegI != VirtReg->end())
- IR.LiveUnionI = LiveUnion->find(IR.VirtRegI->start);
- } else {
- // LiveUnion starts first, perform double binary search.
- IR.LiveUnionI = LiveUnion->find(VirtReg->beginIndex());
- if (IR.LiveUnionI.valid())
- IR.VirtRegI = VirtReg->find(IR.LiveUnionI.start());
- else
- IR.VirtRegI = VirtReg->end();
- }
- findIntersection(FirstInterference);
- assert((IR.VirtRegI == VirtReg->end() || IR.LiveUnionI.valid())
- && "Uninitialized iterator");
- return FirstInterference;
-}
-
-// Treat the result as an iterator and advance to the next interfering pair
-// of segments. This is a plain iterator with no filter.
-bool LiveIntervalUnion::Query::nextInterference(InterferenceResult &IR) const {
- assert(isInterference(IR) && "iteration past end of interferences");
-
- // Advance either the VirtReg or LiveUnion segment to ensure that we visit all
- // unique overlapping pairs.
- if (IR.VirtRegI->end < IR.LiveUnionI.stop()) {
- if (++IR.VirtRegI == VirtReg->end())
- return false;
- }
- else {
- if (!(++IR.LiveUnionI).valid()) {
- IR.VirtRegI = VirtReg->end();
- return false;
- }
- }
- // Short-circuit findIntersection() if possible.
- if (overlap(*IR.VirtRegI, IR.LiveUnionI))
- return true;
-
- // Find the next intersection.
- findIntersection(IR);
- return isInterference(IR);
-}
-
// Scan the vector of interfering virtual registers in this union. Assume it's
// quite small.
bool LiveIntervalUnion::Query::isSeenInterference(LiveInterval *VirtReg) const {
return I != InterferingVRegs.end();
}
-// Count the number of virtual registers in this union that interfere with this
+// Collect virtual registers in this union that interfere with this
// query's live virtual register.
//
-// The number of times that we either advance IR.VirtRegI or call
-// LiveUnion.upperBound() will be no more than the number of holes in
-// VirtReg. So each invocation of collectInterferingVRegs() takes
-// time proportional to |VirtReg Holes| * time(LiveUnion.upperBound()).
+// The query state is one of:
+//
+// 1. CheckedFirstInterference == false: Iterators are uninitialized.
+// 2. SeenAllInterferences == true: InterferingVRegs complete, iterators unused.
+// 3. Iterators left at the last seen intersection.
//
-// For comments on how to speed it up, see Query::findIntersection().
unsigned LiveIntervalUnion::Query::
collectInterferingVRegs(unsigned MaxInterferingRegs) {
- InterferenceResult IR = firstInterference();
- LiveInterval::iterator VirtRegEnd = VirtReg->end();
- LiveInterval *RecentInterferingVReg = NULL;
- while (IR.LiveUnionI.valid()) {
- // Advance the union's iterator to reach an unseen interfering vreg.
- do {
- if (IR.LiveUnionI.value() == RecentInterferingVReg)
- continue;
+ // Fast path return if we already have the desired information.
+ if (SeenAllInterferences || InterferingVRegs.size() >= MaxInterferingRegs)
+ return InterferingVRegs.size();
+
+ // Set up iterators on the first call.
+ if (!CheckedFirstInterference) {
+ CheckedFirstInterference = true;
+
+ // Quickly skip interference check for empty sets.
+ if (VirtReg->empty() || LiveUnion->empty()) {
+ SeenAllInterferences = true;
+ return 0;
+ }
- if (!isSeenInterference(IR.LiveUnionI.value()))
- break;
+ // In most cases, the union will start before VirtReg.
+ VirtRegI = VirtReg->begin();
+ LiveUnionI.setMap(LiveUnion->getMap());
+ LiveUnionI.find(VirtRegI->start);
+ }
- // Cache the most recent interfering vreg to bypass isSeenInterference.
- RecentInterferingVReg = IR.LiveUnionI.value();
+ LiveInterval::iterator VirtRegEnd = VirtReg->end();
+ LiveInterval *RecentReg = nullptr;
+ while (LiveUnionI.valid()) {
+ assert(VirtRegI != VirtRegEnd && "Reached end of VirtReg");
+
+ // Check for overlapping interference.
+ while (VirtRegI->start < LiveUnionI.stop() &&
+ VirtRegI->end > LiveUnionI.start()) {
+ // This is an overlap, record the interfering register.
+ LiveInterval *VReg = LiveUnionI.value();
+ if (VReg != RecentReg && !isSeenInterference(VReg)) {
+ RecentReg = VReg;
+ InterferingVRegs.push_back(VReg);
+ if (InterferingVRegs.size() >= MaxInterferingRegs)
+ return InterferingVRegs.size();
+ }
+ // This LiveUnion segment is no longer interesting.
+ if (!(++LiveUnionI).valid()) {
+ SeenAllInterferences = true;
+ return InterferingVRegs.size();
+ }
+ }
- } while ((++IR.LiveUnionI).valid());
- if (!IR.LiveUnionI.valid())
- break;
+ // The iterators are now not overlapping, LiveUnionI has been advanced
+ // beyond VirtRegI.
+ assert(VirtRegI->end <= LiveUnionI.start() && "Expected non-overlap");
- // Advance the VirtReg iterator until surpassing the next segment in
- // LiveUnion.
- IR.VirtRegI = VirtReg->advanceTo(IR.VirtRegI, IR.LiveUnionI.start());
- if (IR.VirtRegI == VirtRegEnd)
+ // Advance the iterator that ends first.
+ VirtRegI = VirtReg->advanceTo(VirtRegI, LiveUnionI.start());
+ if (VirtRegI == VirtRegEnd)
break;
- // Check for intersection with the union's segment.
- if (overlap(*IR.VirtRegI, IR.LiveUnionI)) {
-
- if (!IR.LiveUnionI.value()->isSpillable())
- SeenUnspillableVReg = true;
-
- if (InterferingVRegs.size() == MaxInterferingRegs)
- // Leave SeenAllInterferences set to false to indicate that at least one
- // interference exists beyond those we collected.
- return MaxInterferingRegs;
-
- InterferingVRegs.push_back(IR.LiveUnionI.value());
-
- // Cache the most recent interfering vreg to bypass isSeenInterference.
- RecentInterferingVReg = IR.LiveUnionI.value();
- ++IR.LiveUnionI;
+ // Detect overlap, handle above.
+ if (VirtRegI->start < LiveUnionI.stop())
continue;
- }
- // VirtRegI may have advanced far beyond LiveUnionI,
- // do a fast intersection test to "catch up"
- IR.LiveUnionI.advanceTo(IR.VirtRegI->start);
+
+ // Still not overlapping. Catch up LiveUnionI.
+ LiveUnionI.advanceTo(VirtRegI->start);
}
SeenAllInterferences = true;
return InterferingVRegs.size();
}
-bool LiveIntervalUnion::Query::checkLoopInterference(MachineLoopRange *Loop) {
- // VirtReg is likely live throughout the loop, so start by checking LIU-Loop
- // overlaps.
- IntervalMapOverlaps<LiveIntervalUnion::Map, MachineLoopRange::Map>
- Overlaps(LiveUnion->getMap(), Loop->getMap());
- if (!Overlaps.valid())
- return false;
-
- // The loop is overlapping an LIU assignment. Check VirtReg as well.
- LiveInterval::iterator VRI = VirtReg->find(Overlaps.start());
-
- for (;;) {
- if (VRI == VirtReg->end())
- return false;
- if (VRI->start < Overlaps.stop())
- return true;
-
- Overlaps.advanceTo(VRI->start);
- if (!Overlaps.valid())
- return false;
- if (Overlaps.start() < VRI->end)
- return true;
+void LiveIntervalUnion::Array::init(LiveIntervalUnion::Allocator &Alloc,
+ unsigned NSize) {
+ // Reuse existing allocation.
+ if (NSize == Size)
+ return;
+ clear();
+ Size = NSize;
+ LIUs = static_cast<LiveIntervalUnion*>(
+ malloc(sizeof(LiveIntervalUnion)*NSize));
+ for (unsigned i = 0; i != Size; ++i)
+ new(LIUs + i) LiveIntervalUnion(Alloc);
+}
- VRI = VirtReg->advanceTo(VRI, Overlaps.start());
- }
+void LiveIntervalUnion::Array::clear() {
+ if (!LIUs)
+ return;
+ for (unsigned i = 0; i != Size; ++i)
+ LIUs[i].~LiveIntervalUnion();
+ free(LIUs);
+ Size = 0;
+ LIUs = nullptr;
}
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