[llvm-dev] Question about LLVM LLJIT Compile time

chris boese via llvm-dev llvm-dev at lists.llvm.org
Wed Jan 29 14:12:30 PST 2020


Hi,

We are using the new LLJIT class in our compiler. We have not been
successful using the parallel JIT feature. When we tried it previously on
multiple modules, our compile-time increased significantly. I don't know if
we are using it incorrectly, or that we miss out on optimizations we get
when running on a single merged module, but it hasn't worked for us yet. We
are pretty far behind HEAD atm, but will try it again soon.

In the meantime, we are trying to find ways to gauge the compilation time
of a module. We pass a single module to the LLJIT instance. Is there is any
information we can get during the JIT construction to let us compare
against other modules we run through JIT? We're trying to find hot spots or
performance issues in our modules. Timers or statistical data would be
helpful if they exist during the execution of the JIT engine.

I imagine parallelizing the JIT will be our best bet for increasing
performance, but we have not been able to use that yet.

Any help/ideas would be appreciated.

Thanks,
Chris
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