1 files changed, 32 insertions, 3 deletions

diff --git a/llvm/lib/Transforms/Utils/LoopUtils.cpp b/llvm/lib/Transforms/Utils/LoopUtils.cpp
index acce8d1..5948512 100644
--- a/llvm/lib/Transforms/Utils/LoopUtils.cpp
+++ b/llvm/lib/Transforms/Utils/LoopUtils.cpp
@@ -604,6 +604,7 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE,
   // Use a map to unique and a vector to guarantee deterministic ordering.
   llvm::SmallDenseSet<DebugVariable, 4> DeadDebugSet;
   llvm::SmallVector<DbgVariableIntrinsic *, 4> DeadDebugInst;
+  llvm::SmallVector<DPValue *, 4> DeadDPValues;
 
   if (ExitBlock) {
     // Given LCSSA form is satisfied, we should not have users of instructions
@@ -628,6 +629,24 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE,
                    "Unexpected user in reachable block");
           U.set(Poison);
         }
+
+        // RemoveDIs: do the same as below for DPValues.
+        if (Block->IsNewDbgInfoFormat) {
+          for (DPValue &DPV :
+               llvm::make_early_inc_range(I.getDbgValueRange())) {
+            DebugVariable Key(DPV.getVariable(), DPV.getExpression(),
+                              DPV.getDebugLoc().get());
+            if (!DeadDebugSet.insert(Key).second)
+              continue;
+            // Unlinks the DPV from it's container, for later insertion.
+            DPV.removeFromParent();
+            DeadDPValues.push_back(&DPV);
+          }
+        }
+
+        // For one of each variable encountered, preserve a debug intrinsic (set
+        // to Poison) and transfer it to the loop exit. This terminates any
+        // variable locations that were set during the loop.
         auto *DVI = dyn_cast<DbgVariableIntrinsic>(&I);
         if (!DVI)
           continue;
@@ -642,12 +661,22 @@ void llvm::deleteDeadLoop(Loop *L, DominatorTree *DT, ScalarEvolution *SE,
     // be be replaced with undef. Loop invariant values will still be available.
     // Move dbg.values out the loop so that earlier location ranges are still
     // terminated and loop invariant assignments are preserved.
-    Instruction *InsertDbgValueBefore = ExitBlock->getFirstNonPHI();
-    assert(InsertDbgValueBefore &&
+    DIBuilder DIB(*ExitBlock->getModule());
+    BasicBlock::iterator InsertDbgValueBefore =
+        ExitBlock->getFirstInsertionPt();
+    assert(InsertDbgValueBefore != ExitBlock->end() &&
            "There should be a non-PHI instruction in exit block, else these "
            "instructions will have no parent.");
+
     for (auto *DVI : DeadDebugInst)
-      DVI->moveBefore(InsertDbgValueBefore);
+      DVI->moveBefore(*ExitBlock, InsertDbgValueBefore);
+
+    // Due to the "head" bit in BasicBlock::iterator, we're going to insert
+    // each DPValue right at the start of the block, wheras dbg.values would be
+    // repeatedly inserted before the first instruction. To replicate this
+    // behaviour, do it backwards.
+    for (DPValue *DPV : llvm::reverse(DeadDPValues))
+      ExitBlock->insertDPValueBefore(DPV, InsertDbgValueBefore);
   }
 
   // Remove the block from the reference counting scheme, so that we can