2 files changed, 28 insertions, 2 deletions
diff --git a/lib/CodeGen/SplitKit.cpp b/lib/CodeGen/SplitKit.cpp
index 4bf3a7a..89e85bd 100644
--- a/lib/CodeGen/SplitKit.cpp
+++ b/lib/CodeGen/SplitKit.cpp
@@ -317,6 +317,7 @@ void SplitEditor::reset(LiveRangeEdit &LRE, ComplementSpillMode SM) {
   Edit = &LRE;
   SpillMode = SM;
   OpenIdx = 0;
+  OverlappedComplement.clear();
   RegAssign.clear();
   Values.clear();
 
@@ -391,6 +392,16 @@ void SplitEditor::markComplexMapped(unsigned RegIdx, const VNInfo *ParentVNI) {
   VNI = 0;
 }
 
+void SplitEditor::markOverlappedComplement(const VNInfo *ParentVNI) {
+  if (OverlappedComplement.insert(ParentVNI))
+    markComplexMapped(0, ParentVNI);
+}
+
+bool SplitEditor::needsRecompute(unsigned RegIdx, const VNInfo *ParentVNI) {
+  return (RegIdx == 0 && OverlappedComplement.count(ParentVNI)) ||
+    Edit->didRematerialize(ParentVNI);
+}
+
 VNInfo *SplitEditor::defFromParent(unsigned RegIdx,
                                    VNInfo *ParentVNI,
                                    SlotIndex UseIdx,
@@ -575,7 +586,7 @@ void SplitEditor::overlapIntv(SlotIndex Start, SlotIndex End) {
 
   // The complement interval will be extended as needed by LRCalc.extend().
   if (ParentVNI)
-    markComplexMapped(0, ParentVNI);
+    markOverlappedComplement(ParentVNI);
   DEBUG(dbgs() << "    overlapIntv [" << Start << ';' << End << "):");
   RegAssign.insert(Start, End, OpenIdx);
   DEBUG(dump());
@@ -623,7 +634,7 @@ bool SplitEditor::transferValues() {
 
       // Skip rematerialized values, we need to use LRCalc.extend() and
       // extendPHIKillRanges() to completely recompute the live ranges.
-      if (Edit->didRematerialize(ParentVNI)) {
+      if (needsRecompute(RegIdx, ParentVNI)) {
         DEBUG(dbgs() << "(remat)");
         Skipped = true;
         Start = End;
diff --git a/lib/CodeGen/SplitKit.h b/lib/CodeGen/SplitKit.h
index 1a4937c..5abdd4c 100644
--- a/lib/CodeGen/SplitKit.h
+++ b/lib/CodeGen/SplitKit.h
@@ -250,6 +250,10 @@ private:
   /// The current spill mode, selected by reset().
   ComplementSpillMode SpillMode;
 
+  /// Parent interval values where the complement interval may be overlapping
+  /// other intervals.
+  SmallPtrSet<const VNInfo*, 8> OverlappedComplement;
+
   typedef IntervalMap<SlotIndex, unsigned> RegAssignMap;
 
   /// Allocator for the interval map. This will eventually be shared with
@@ -296,6 +300,17 @@ private:
   /// of the number of defs.
   void markComplexMapped(unsigned RegIdx, const VNInfo *ParentVNI);
 
+  /// markOverlappedComplement - Mark ParentVNI as being overlapped in the
+  /// complement interval.  The complement interval may overlap other intervals
+  /// after overlapIntv has been called, or when in spill mode.
+  void markOverlappedComplement(const VNInfo *ParentVNI);
+
+  /// needsRecompute - Returns true if the live range of ParentVNI needs to be
+  /// recomputed in RegIdx using LiveRangeCalc::extend.  This is the case if
+  /// the value has been rematerialized, or when back-copies have been hoisted
+  /// in spill mode.
+  bool needsRecompute(unsigned RegIdx, const VNInfo *ParentVNI);
+
   /// defFromParent - Define Reg from ParentVNI at UseIdx using either
   /// rematerialization or a COPY from parent. Return the new value.
   VNInfo *defFromParent(unsigned RegIdx,