commit 97137e894e03f837dde3d81d37b19dd89706dd66
author Jeremy Morse <jeremy.morse@sony.com> Tue Dec 05 15:41:00 2023 +0000
committer Copybara-Service <copybara-worker@google.com> Tue Dec 05 07:47:29 2023 -0800
tree af604e8db38064006d6e51633f3c209ac867796d
parent 1fa887393bcf1c16fd92f7bb558b04862832c5c8

[DebugInfo][RemoveDIs] Avoid leaking trailing DPMarkers (#74458)

In the debug-info-splice implementation, we need to be careful to delete
trailing DPMarkers from blocks when we splice their contents out. This
is equivalent to removing the terminator from a block, then splicing the
rest of it's contents to another block: any DPValues trailing at the end
of the block get moved and we need to clean up afterwards.

GitOrigin-RevId: 71809cfc7ae2fc69b5f6a2069354e74b320ec8d3

lib/IR/BasicBlock.cpp

diff --git a/lib/IR/BasicBlock.cpp b/lib/IR/BasicBlock.cpp
index 3ac5faf..872386d 100644
--- a/lib/IR/BasicBlock.cpp
+++ b/lib/IR/BasicBlock.cpp
@@ -770,6 +770,7 @@
 
   // Transfer DPValues from the trailing position onto the terminator.
   Term->DbgMarker->absorbDebugValues(*TrailingDPValues, false);
+  TrailingDPValues->eraseFromParent();
   deleteTrailingDPValues();
 }
 
@@ -813,6 +814,7 @@
 
     DPMarker *M = Dest->DbgMarker;
     M->absorbDebugValues(*SrcTrailingDPValues, InsertAtHead);
+    SrcTrailingDPValues->eraseFromParent();
     Src->deleteTrailingDPValues();
     return;
   }
@@ -920,6 +922,7 @@
   // Use this flag to signal the abnormal case, where we don't want to copy the
   // DPValues ahead of the "Last" position.
   bool ReadFromTail = !Last.getTailBit();
+  bool LastIsEnd = (Last == Src->end());
 
   /*
     Here's an illustration of what we're about to do. We have two blocks, this
@@ -995,12 +998,16 @@
     DPMarker *OntoDest = getMarker(Dest);
     DPMarker *FromLast = Src->getMarker(Last);
     OntoDest->absorbDebugValues(*FromLast, true);
+    if (LastIsEnd) {
+      FromLast->eraseFromParent();
+      deleteTrailingDPValues();
+    }
   }
 
   // If we're _not_ reading from the head of First, i.e. the "++++" DPValues,
   // move their markers onto Last. They remain in the Src block. No action
   // needed.
-  if (!ReadFromHead) {
+  if (!ReadFromHead && First->hasDbgValues()) {
     DPMarker *OntoLast = Src->createMarker(Last);
     DPMarker *FromFirst = Src->createMarker(First);
     OntoLast->absorbDebugValues(*FromFirst,
@@ -1030,6 +1037,7 @@
     DPMarker *TrailingDPValues = getTrailingDPValues();
     if (TrailingDPValues) {
       FirstMarker->absorbDebugValues(*TrailingDPValues, true);
+      TrailingDPValues->eraseFromParent();
       deleteTrailingDPValues();
     }
   }