//
//===----------------------------------------------------------------------===//
-#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);
while (SegPos.valid()) {
}
// 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 " << PrintReg(RepReg, TRI);
if (empty()) {
OS << " empty\n";
return;
}
#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() {
- // Search until reaching the end of the LiveUnion segments.
- LiveInterval::iterator VirtRegEnd = VirtReg->end();
- if (VirtRegI == VirtRegEnd)
- return;
- while (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.
- VirtRegI = VirtReg->advanceTo(VirtRegI, LiveUnionI.start());
- if (VirtRegI == VirtRegEnd)
- break; // Retain current (nonoverlapping) LiveUnionI
-
- // VirtRegI may have advanced far beyond LiveUnionI, catch up.
- LiveUnionI.advanceTo(VirtRegI->start);
-
- // Check if no LiveUnionI exists with VirtRegI->Start < LiveUnionI.end
- if (!LiveUnionI.valid())
- break;
- if (LiveUnionI.start() < VirtRegI->end) {
- assert(overlap(*VirtRegI, LiveUnionI) && "upperBound postcondition");
- break;
- }
- }
- if (!LiveUnionI.valid())
- VirtRegI = VirtRegEnd;
-}
-
// 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) {
// Fast path return if we already have the desired information.
// Set up iterators on the first call.
if (!CheckedFirstInterference) {
CheckedFirstInterference = true;
- LiveUnionI.setMap(LiveUnion->getMap());
// Quickly skip interference check for empty sets.
if (VirtReg->empty() || LiveUnion->empty()) {
- VirtRegI = VirtReg->end();
- } else if (VirtReg->beginIndex() < LiveUnion->startIndex()) {
- // VirtReg starts first, perform double binary search.
- VirtRegI = VirtReg->find(LiveUnion->startIndex());
- if (VirtRegI != VirtReg->end())
- LiveUnionI.find(VirtRegI->start);
- } else {
- // LiveUnion starts first, perform double binary search.
- LiveUnionI.find(VirtReg->beginIndex());
- if (LiveUnionI.valid())
- VirtRegI = VirtReg->find(LiveUnionI.start());
- else
- VirtRegI = VirtReg->end();
+ SeenAllInterferences = true;
+ return 0;
}
- findIntersection();
- assert((VirtRegI == VirtReg->end() || LiveUnionI.valid())
- && "Uninitialized iterator");
+
+ // In most cases, the union will start before VirtReg.
+ VirtRegI = VirtReg->begin();
+ LiveUnionI.setMap(LiveUnion->getMap());
+ LiveUnionI.find(VirtRegI->start);
}
LiveInterval::iterator VirtRegEnd = VirtReg->end();
- LiveInterval *RecentInterferingVReg = NULL;
- if (VirtRegI != VirtRegEnd) while (LiveUnionI.valid()) {
- // Advance the union's iterator to reach an unseen interfering vreg.
- do {
- if (LiveUnionI.value() == RecentInterferingVReg)
- continue;
-
- if (!isSeenInterference(LiveUnionI.value()))
- break;
+ 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();
+ }
+ }
- // Cache the most recent interfering vreg to bypass isSeenInterference.
- RecentInterferingVReg = LiveUnionI.value();
+ // The iterators are now not overlapping, LiveUnionI has been advanced
+ // beyond VirtRegI.
+ assert(VirtRegI->end <= LiveUnionI.start() && "Expected non-overlap");
- } while ((++LiveUnionI).valid());
- if (!LiveUnionI.valid())
- break;
-
- // Advance the VirtReg iterator until surpassing the next segment in
- // LiveUnion.
+ // 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(*VirtRegI, LiveUnionI)) {
-
- if (!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(LiveUnionI.value());
-
- // Cache the most recent interfering vreg to bypass isSeenInterference.
- RecentInterferingVReg = LiveUnionI.value();
- ++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"
+
+ // 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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