1 files changed, 36 insertions, 52 deletions

diff --git a/llvm/lib/CodeGen/LiveDebugVariables.cpp b/llvm/lib/CodeGen/LiveDebugVariables.cpp
index 6543287..6dac7db 100644
--- a/llvm/lib/CodeGen/LiveDebugVariables.cpp
+++ b/llvm/lib/CodeGen/LiveDebugVariables.cpp
@@ -534,65 +534,49 @@ bool LDVImpl::collectDebugValues(MachineFunction &mf) {
   return Changed;
 }
 
-void UserValue::extendDef(SlotIndex Idx, unsigned LocNo,
-                          LiveRange *LR, const VNInfo *VNI,
-                          SmallVectorImpl<SlotIndex> *Kills,
+/// We only propagate DBG_VALUES locally here. LiveDebugValues performs a
+/// data-flow analysis to propagate them beyond basic block boundaries.
+void UserValue::extendDef(SlotIndex Idx, unsigned LocNo, LiveRange *LR,
+                          const VNInfo *VNI, SmallVectorImpl<SlotIndex> *Kills,
                           LiveIntervals &LIS, MachineDominatorTree &MDT,
                           UserValueScopes &UVS) {
-  SmallVector<SlotIndex, 16> Todo;
-  Todo.push_back(Idx);
-  do {
-    SlotIndex Start = Todo.pop_back_val();
-    MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
-    SlotIndex Stop = LIS.getMBBEndIdx(MBB);
-    LocMap::iterator I = locInts.find(Start);
-
-    // Limit to VNI's live range.
-    bool ToEnd = true;
-    if (LR && VNI) {
-      LiveInterval::Segment *Segment = LR->getSegmentContaining(Start);
-      if (!Segment || Segment->valno != VNI) {
-        if (Kills)
-          Kills->push_back(Start);
-        continue;
-      }
-      if (Segment->end < Stop)
-        Stop = Segment->end, ToEnd = false;
-    }
-
-    // There could already be a short def at Start.
-    if (I.valid() && I.start() <= Start) {
-      // Stop when meeting a different location or an already extended interval.
-      Start = Start.getNextSlot();
-      if (I.value() != LocNo || I.stop() != Start)
-        continue;
-      // This is a one-slot placeholder. Just skip it.
-      ++I;
+  SlotIndex Start = Idx;
+  MachineBasicBlock *MBB = LIS.getMBBFromIndex(Start);
+  SlotIndex Stop = LIS.getMBBEndIdx(MBB);
+  LocMap::iterator I = locInts.find(Start);
+
+  // Limit to VNI's live range.
+  bool ToEnd = true;
+  if (LR && VNI) {
+    LiveInterval::Segment *Segment = LR->getSegmentContaining(Start);
+    if (!Segment || Segment->valno != VNI) {
+      if (Kills)
+        Kills->push_back(Start);
+      return;
     }
+    if (Segment->end < Stop)
+      Stop = Segment->end, ToEnd = false;
+  }
 
-    // Limited by the next def.
-    if (I.valid() && I.start() < Stop)
-      Stop = I.start(), ToEnd = false;
-    // Limited by VNI's live range.
-    else if (!ToEnd && Kills)
-      Kills->push_back(Stop);
+  // There could already be a short def at Start.
+  if (I.valid() && I.start() <= Start) {
+    // Stop when meeting a different location or an already extended interval.
+    Start = Start.getNextSlot();
+    if (I.value() != LocNo || I.stop() != Start)
+      return;
+    // This is a one-slot placeholder. Just skip it.
+    ++I;
+  }
 
-    if (Start >= Stop)
-      continue;
+  // Limited by the next def.
+  if (I.valid() && I.start() < Stop)
+    Stop = I.start(), ToEnd = false;
+  // Limited by VNI's live range.
+  else if (!ToEnd && Kills)
+    Kills->push_back(Stop);
 
+  if (Start < Stop)
     I.insert(Start, Stop, LocNo);
-
-    // If we extended to the MBB end, propagate down the dominator tree.
-    if (!ToEnd)
-      continue;
-    const std::vector<MachineDomTreeNode*> &Children =
-      MDT.getNode(MBB)->getChildren();
-    for (unsigned i = 0, e = Children.size(); i != e; ++i) {
-      MachineBasicBlock *MBB = Children[i]->getBlock();
-      if (UVS.dominates(MBB))
-        Todo.push_back(LIS.getMBBStartIdx(MBB));
-    }
-  } while (!Todo.empty());
 }
 
 void