Re: JIT compiling with LLVM v9.0

On 26.01.2018 11:23, Andres Freund wrote:
> Hi,
>
> Thanks for testing things out!
>
Thank you for this work.
One more question: do you have any idea how to profile JITed code?
There is no LLVMOrcRegisterPerf in LLVM 5, so jit_profiling_support
option does nothing.
And without it perf is not able to unwind stack trace for generated code.
A attached the produced profile, looks like "unknown" bar corresponds to
JIT code.

There is NoFramePointerElim option in LLVMMCJITCompilerOptions
structure, but it requires use of ExecutionEngine.
Something like this:

    mod = llvm_mutable_module(context);
    {
        struct LLVMMCJITCompilerOptions options;
        LLVMExecutionEngineRef jit;
        char* error;
        LLVMCreateExecutionEngineForModule(&jit, mod, &error);
        LLVMInitializeMCJITCompilerOptions(&options, sizeof(options));
        options.NoFramePointerElim = 1;
        LLVMCreateMCJITCompilerForModule(&jit, mod, &options,
sizeof(options),
                                         &error);
    }
    ...

But you are compiling code using LLVMOrcAddEagerlyCompiledIR
and I find no way to pass no-omit-frame pointer option here.

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Konstantin Knizhnik
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