[Orc] Add a comment about member variable dependencies to OrcMCJITReplacement.

The comment explains the reason behind the change in member variable order in
r312086.

Thanks to Philip Reames for the suggestion.

llvm-svn: 312205

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
index 743d5e2307c..cb48d6cb230 100644
--- a/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
+++ b/llvm/lib/ExecutionEngine/Orc/OrcMCJITReplacement.h
@@ -381,6 +381,9 @@ private:
   std::shared_ptr<JITSymbolResolver> ClientResolver;
   Mangler Mang;
 
+  // IMPORTANT: ShouldDelete *must* come before LocalModules: The shared_ptr
+  // delete blocks in LocalModules refer to the ShouldDelete map, so
+  // LocalModules needs to be destructed before ShouldDelete.
   std::map<Module*, bool> ShouldDelete;
   std::vector<std::shared_ptr<Module>> LocalModules;