Codegen: don't incorrectly share metadata across llvm modules #4976
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RX14
approved these changes
Sep 15, 2017
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Since CI is broken in master, and this passed (a good sign!), let's merge and see if it gets fixed :-D |
bcardiff
reviewed
Sep 15, 2017
| @debug_types_per_module ||= | ||
| {} of LLVM::Module => Hash(Type, LibLLVMExt::Metadata?) | ||
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| debug_types_per_module[llvm_module] ||= {} of Type => LibLLVMExt::Metadata? |
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There is no invocation to debug_type_cache with arguments.
Why not use @llvm_mod directly instead of llvm_module as the index to access debug_types_per_module?
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Good idea! Please send a PR (I'll be busy today, water leak under my apartment :/)
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Fixes #4973
(or so I think)
At least I tried to reproduce the invalid memory access with this code and it didn't happen anymore.
I'm 99% sure this was the cause: metadata nodes, which belong to an LLVM::Module, were also being used in other modules. I confirmed this by changing the code a bit and adding checks (leaving the checks would be very inefficient, so I left them out). So when a module was disposed its metadata was disposed, and then when a second module was disposed that same metadata would be disposed again, leading to a crash.
We'll know for sure if we don't see those awful crashes in CI anymore :-)