[Mesa-dev] [RFC][PATCH] gallivm: Clean up llvm data structures upon destruction.

[Marek Olšák]

This is OK but the code also needs to compile with Visual C++.

Marek

On Wed, Jul 18, 2018 at 4:34 PM, David Riley <davidriley at chromium.org> wrote:
> Without this change, dlopen()/dlclose() of any driver results in memory
> being leaked which becomes problematic if things are being reinitialized
> repeatedly (eg from a fuzzer).
>
> Even with this change, repeated dlopen()/dlclose() results in a single
> LLVM mutex being allocated and never freed (used to synchronize
> ManagedStatic).  I've spoken to some LLVM folks and haven't come up with
> a great answer on avoiding that memory leak and not running into issues
> with signal handlers and/or global destructors being called after
> llvm_shutdown().
>
> With regards to the RFC, there's potentially some issues here with
> multiple drivers being loaded with separate LLVM instances and being
> shared due to the dlopen() being done with RTLD_GLOBAL, but this falls
> squarely outside my realm of confidence.
>
> ---
>  src/gallium/auxiliary/gallivm/lp_bld_misc.cpp | 10 ++++++++++
>  1 file changed, 10 insertions(+)
>
> diff --git a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> index 79dbedbb56..d537ae6029 100644
> --- a/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> +++ b/src/gallium/auxiliary/gallivm/lp_bld_misc.cpp
> @@ -68,6 +68,7 @@
>  #endif
>  #include <llvm/Support/CommandLine.h>
>  #include <llvm/Support/Host.h>
> +#include <llvm/Support/ManagedStatic.h>
>  #include <llvm/Support/PrettyStackTrace.h>
>
>  #include <llvm/Support/TargetSelect.h>
> @@ -813,3 +814,12 @@ lp_is_function(LLVMValueRef v)
>         return llvm::isa<llvm::Function>(llvm::unwrap(v));
>  #endif
>  }
> +
> +/*
> + * Attempt to clean up to allow drivers to be loaded/unloaded without
> + * leaking excessive amounts of memory.
> + */
> +__attribute__((destructor)) static void llvm_fini()
> +{
> +   llvm::llvm_shutdown();
> +}
> --
> 2.18.0.203.gfac676dfb9-goog
>
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