CODEWITHSUNDEEP
c++llvm
Minor Threat
Minor Threat

Reputation: 2095

How to make llvm jit work in MSVC++

It appears that Kaleidoscope example in LLVM has been broken, at least in MSVC++ x64 for a quite while, maybe several months. It doesn't work in MCJIT and in their new Orc JIT framework for a same reason.

// Get the address of the JIT'd function in memory.
auto ExprSymbol = J.findUnmangledSymbol("__anon_expr");

This expression returns null and cause null pointer error as a result. I can't guess how to make workaround at this moment because call tree is too deep there and may require ~few days of debugging. But in theory, this code is educational and shouldn't cause trouble for newcomers. So maybe i'm doing something wrong.

Upvotes: 1

Views: 480

Answers (2)

Stefan Gränitz
Stefan Gränitz

Reputation: 53

For me the easiest way to workaround this was to patch the findMangledSymbol function, calling CompileLayer.findSymbolIn with bExportedSymbolsOnly set to false. It doesn't fix the problem but avoids the symptom.

Upvotes: 1

Minor Threat
Minor Threat

Reputation: 2095

Lang Hames from the llvm mailing list was able to answer this question. It appears that method COFFObjectFile::getSymbolFlags doesn't enable SF_Export flag at all, thus making all created symbols invisible for the Kaleidoscope's findSymbol method in the Windows platform. It is possible to get access to non-exported symbols though, so some kind of workaround is possible.

Upvotes: 0

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