1 files changed, 18 insertions, 4 deletions

diff --git a/lib/CodeGen/LiveIntervalUnion.cpp b/lib/CodeGen/LiveIntervalUnion.cpp
index 205f28a..b67f966 100644
--- a/lib/CodeGen/LiveIntervalUnion.cpp
+++ b/lib/CodeGen/LiveIntervalUnion.cpp
@@ -35,12 +35,20 @@ void LiveIntervalUnion::unify(LiveInterval &VirtReg) {
   LiveInterval::iterator RegEnd = VirtReg.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.
@@ -168,6 +176,7 @@ LiveIntervalUnion::Query::firstInterference() {
     return FirstInterference;
   CheckedFirstInterference = true;
   InterferenceResult &IR = FirstInterference;
+  IR.LiveUnionI.setMap(LiveUnion->getMap());
 
   // Quickly skip interference check for empty sets.
   if (VirtReg->empty() || LiveUnion->empty()) {
@@ -176,10 +185,10 @@ LiveIntervalUnion::Query::firstInterference() {
     // 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);
+      IR.LiveUnionI.find(IR.VirtRegI->start);
   } else {
     // LiveUnion starts first, perform double binary search.
-    IR.LiveUnionI = LiveUnion->find(VirtReg->beginIndex());
+    IR.LiveUnionI.find(VirtReg->beginIndex());
     if (IR.LiveUnionI.valid())
       IR.VirtRegI = VirtReg->find(IR.LiveUnionI.start());
     else
@@ -235,7 +244,7 @@ bool LiveIntervalUnion::Query::isSeenInterference(LiveInterval *VirtReg) const {
 //
 // For comments on how to speed it up, see Query::findIntersection().
 unsigned LiveIntervalUnion::Query::
-collectInterferingVRegs(unsigned MaxInterferingRegs) {
+collectInterferingVRegs(unsigned MaxInterferingRegs, float MaxWeight) {
   InterferenceResult IR = firstInterference();
   LiveInterval::iterator VirtRegEnd = VirtReg->end();
   LiveInterval *RecentInterferingVReg = NULL;
@@ -277,6 +286,11 @@ collectInterferingVRegs(unsigned MaxInterferingRegs) {
       // Cache the most recent interfering vreg to bypass isSeenInterference.
       RecentInterferingVReg = IR.LiveUnionI.value();
       ++IR.LiveUnionI;
+
+      // Stop collecting when the max weight is exceeded.
+      if (RecentInterferingVReg->weight >= MaxWeight)
+        return InterferingVRegs.size();
+
       continue;
     }
     // VirtRegI may have advanced far beyond LiveUnionI,