[PATCH] D97780: Control lifetime of SectionMemoryManager's DefaultMMapper

[Axel Naumann via Phabricator via llvm-commits]

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As the `DefaultMMapper` object is a namespace-level variable, its destruction happens unsynchronized with uses. `~SectionMemoryManager()` needs `MMapper` which might have been destructed before the call to `~SectionMemoryManager()` in cases where `~SectionMemoryManager()` is triggered by some other static destruction.

To sort this out, make the DefaultMMapper object function-local. That way its construction happens before the first use (which might be static initialization), and its destruction is sequenced after that use's static destruction. This allows the use of the default `SectionMemoryManager` by objects with static storage duration.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D97780

Files:
  llvm/lib/ExecutionEngine/SectionMemoryManager.cpp


Index: llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
===================================================================
--- llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
+++ llvm/lib/ExecutionEngine/SectionMemoryManager.cpp
@@ -264,10 +264,13 @@
   }
 };
 
-DefaultMMapper DefaultMMapperInstance;
+DefaultMMapper &getDefaultMMapperInstance() {
+  static DefaultMMapper Mapper;
+  return Mapper;
+};
 } // namespace
 
 SectionMemoryManager::SectionMemoryManager(MemoryMapper *MM)
-    : MMapper(MM ? *MM : DefaultMMapperInstance) {}
+    : MMapper(MM ? *MM : getDefaultMMapperInstance()) {}
 
 } // namespace llvm


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