[PATCH] D72469: SCC: Allow ReplaceNode to safely support insertion

[Warren Ristow via Phabricator via llvm-commits]

This revision was automatically updated to reflect the committed changes.
Closed by commit rGf7e9f4f4c502: SCC: Allow ReplaceNode to safely support insertion (authored by wristow).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D72469/new/

https://reviews.llvm.org/D72469

Files:
  llvm/include/llvm/ADT/SCCIterator.h


Index: llvm/include/llvm/ADT/SCCIterator.h
===================================================================
--- llvm/include/llvm/ADT/SCCIterator.h
+++ llvm/include/llvm/ADT/SCCIterator.h
@@ -134,7 +134,10 @@
   /// has been deleted, and \c New is to be used in its place.
   void ReplaceNode(NodeRef Old, NodeRef New) {
     assert(nodeVisitNumbers.count(Old) && "Old not in scc_iterator?");
-    nodeVisitNumbers[New] = nodeVisitNumbers[Old];
+    // Do the assignment in two steps, in case 'New' is not yet in the map, and
+    // inserting it causes the map to grow.
+    auto tempVal = nodeVisitNumbers[Old];
+    nodeVisitNumbers[New] = tempVal;
     nodeVisitNumbers.erase(Old);
   }
 };


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