3 files changed, 39 insertions, 2 deletions
diff --git a/lib/CodeGen/LiveIntervalUnion.cpp b/lib/CodeGen/LiveIntervalUnion.cpp
index 079468a4f0..7ebe96f066 100644
--- a/lib/CodeGen/LiveIntervalUnion.cpp
+++ b/lib/CodeGen/LiveIntervalUnion.cpp
@@ -16,6 +16,7 @@
 #define DEBUG_TYPE "regalloc"
 #include "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"
@@ -284,3 +285,30 @@ collectInterferingVRegs(unsigned MaxInterferingRegs) {
   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;
+
+    VRI = VirtReg->advanceTo(VRI, Overlaps.start());
+  }
+}
diff --git a/lib/CodeGen/LiveIntervalUnion.h b/lib/CodeGen/LiveIntervalUnion.h
index d8dcbda8d3..ff23cf61a3 100644
--- a/lib/CodeGen/LiveIntervalUnion.h
+++ b/lib/CodeGen/LiveIntervalUnion.h
@@ -24,6 +24,7 @@
 
 namespace llvm {
 
+class MachineLoopRange;
 class TargetRegisterInfo;
 
 #ifndef NDEBUG
@@ -76,6 +77,10 @@ public:
   bool empty() const { return Segments.empty(); }
   SlotIndex startIndex() const { return Segments.start(); }
 
+  // Provide public access to the underlying map to allow overlap iteration.
+  typedef LiveSegments Map;
+  const Map &getMap() { return Segments; }
+
   // Add a live virtual register to this union and merge its segments.
   void unify(LiveInterval &VirtReg);
 
@@ -223,6 +228,10 @@ public:
       return InterferingVRegs;
     }
 
+    /// checkLoopInterference - Return true if there is interference overlapping
+    /// Loop.
+    bool checkLoopInterference(MachineLoopRange*);
+
     void print(raw_ostream &OS, const TargetRegisterInfo *TRI);
   private:
     Query(const Query&);          // DO NOT IMPLEMENT
diff --git a/lib/CodeGen/MachineLoopRanges.cpp b/lib/CodeGen/MachineLoopRanges.cpp
index 9af49b04ab..9ee6c5bd12 100644
--- a/lib/CodeGen/MachineLoopRanges.cpp
+++ b/lib/CodeGen/MachineLoopRanges.cpp
@@ -69,13 +69,13 @@ MachineLoopRange::MachineLoopRange(const MachineLoop *loop,
 /// overlaps - Return true if this loop overlaps the given range of machine
 /// instructions.
 bool MachineLoopRange::overlaps(SlotIndex Start, SlotIndex Stop) {
-  RangeMap::const_iterator I = Intervals.find(Start);
+  Map::const_iterator I = Intervals.find(Start);
   return I.valid() && Stop > I.start();
 }
 
 void MachineLoopRange::print(raw_ostream &OS) const {
   OS << "Loop#" << Loop->getHeader()->getNumber() << " =";
-  for (RangeMap::const_iterator I = Intervals.begin(); I.valid(); ++I)
+  for (Map::const_iterator I = Intervals.begin(); I.valid(); ++I)
     OS << " [" << I.start() << ';' << I.stop() << ')';
 }