[Lldb-commits] [PATCH] D128166: ManagedStatic: Destroy from destructor

[Nicolai Hähnle via Phabricator via lldb-commits]

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This allows LLVM to be safely loaded and unloaded as a shared library
without leaking memory:

Consider the scenario where shared library Foo links against LLVM as
a shared library, and Foo may be loaded and unloaded multiple times
in the same process. Should Foo call llvm_shutdown or not? If it does
not, and LLVM is also loaded and unloaded multiple times, then
memory is leaked. If it does call llvm_shutdown and LLVM *isn't*
also unloaded, the state of LLVM's global statics is corrupted because
while the ManagedStatics may be re-initialized, *other* global
constructors aren't re-run.

Keep in mind that Foo itself may use ManagedStatic. If Foo is unloaded
but LLVM isn't, those statics should be destroyed.

The safe solution is to skip llvm_shutdown() altogether and destroy
managed statics from their destructor.

LLD relies on being able to call _exit() and still get some side-effects
of managed static destructors. We make this expectation much more
explicit.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D128166

Files:
  bolt/tools/driver/llvm-bolt.cpp
  bolt/tools/merge-fdata/merge-fdata.cpp
  clang/include/clang/Frontend/CompilerInstance.h
  clang/tools/clang-repl/ClangRepl.cpp
  clang/unittests/Interpreter/ExceptionTests/InterpreterExceptionTest.cpp
  clang/unittests/Interpreter/InterpreterTest.cpp
  clang/utils/TableGen/TableGen.cpp
  libclc/utils/prepare-builtins.cpp
  lld/Common/ErrorHandler.cpp
  lldb/tools/driver/Driver.cpp
  lldb/tools/lldb-test/lldb-test.cpp
  lldb/unittests/Utility/LogTest.cpp
  lldb/utils/TableGen/LLDBTableGen.cpp
  llvm/docs/ProgrammersManual.rst
  llvm/examples/BrainF/BrainFDriver.cpp
  llvm/examples/HowToUseJIT/HowToUseJIT.cpp
  llvm/include/llvm-c/Core.h
  llvm/include/llvm/ADT/Statistic.h
  llvm/include/llvm/PassRegistry.h
  llvm/include/llvm/Support/DynamicLibrary.h
  llvm/include/llvm/Support/FastShutdown.h
  llvm/include/llvm/Support/InitLLVM.h
  llvm/include/llvm/Support/ManagedStatic.h
  llvm/lib/IR/Core.cpp
  llvm/lib/IR/Pass.cpp
  llvm/lib/IR/PassRegistry.cpp
  llvm/lib/Support/CMakeLists.txt
  llvm/lib/Support/FastShutdown.cpp
  llvm/lib/Support/InitLLVM.cpp
  llvm/lib/Support/ManagedStatic.cpp
  llvm/lib/Support/Parallel.cpp
  llvm/lib/Support/Statistic.cpp
  llvm/lib/Support/Unix/DynamicLibrary.inc
  llvm/lib/Support/Unix/Signals.inc
  llvm/lib/Support/Windows/DynamicLibrary.inc
  llvm/tools/gold/gold-plugin.cpp
  llvm/tools/llvm-gsymutil/llvm-gsymutil.cpp
  llvm/unittests/ExecutionEngine/ExecutionEngineTest.cpp
  llvm/unittests/Support/DynamicLibrary/DynamicLibraryTest.cpp
  llvm/utils/KillTheDoctor/KillTheDoctor.cpp
  mlir/tools/mlir-vulkan-runner/mlir-vulkan-runner.cpp
  polly/lib/External/isl/interface/extract_interface.cc

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