[LLVMdev] Trouble using the MCJIT: "Target does not support MC emission" error

[Ralf Karrenberg]

Hi Matt,

I am unsure about MCJIT, but I guess the problem is the same.
Just like when invoking llc, you need to pass the information to use AVX 
(llc -mattr=+avx).
I guess the corresponding code should look like this:

     llvm::EngineBuilder engineBuilder(module);
     engineBuilder.setErrorStr(&eeError);
     engineBuilder.setEngineKind(llvm::EngineKind::JIT);
     engineBuilder.setUseMCJIT(true);
     engineBuilder.setMCPU("corei7-avx");
     std::vector<std::string> attrs;
     attrs.push_back("avx");
     engineBuilder.setMAttrs(attrs);
     llvm::ExecutionEngine *ee = engineBuilder.create();

Note that I have just today filed a bug report also related to jitted 
AVX: http://llvm.org/bugs/show_bug.cgi?id=10742
Thus, it might very well be the case that I am also mistaken and need to 
do something different.

Best,
Ralf

Am 25.08.2011 13:16, schrieb Matt Pharr:
> I'm trying to wire up some code to use the MC-based JIT; my understanding is that it should be able to JIT AVX code (and that the regular JIT cannot).  However, I'm getting the error "Target does not support MC emission!" when I call EngineBuilder::create().  I assume that I'm just not doing something necessary for initialization, but I'm not sure what it would be--I am calling all of:
>
>      llvm::InitializeNativeTarget();
>      llvm::InitializeAllTargetMCs();
>      LLVMLinkInMCJIT();
>      LLVMLinkInJIT();
>
> and the module I'm trying to load does have a reasonable target:
>
> target triple = "x86_64-apple-darwin11.0.0"
>
> I've attached a short test case that has the sequence of calls that I'm making and one of the bitcode files I'm trying to use.  I'd be happy for any guidance or suggestions.
>
> Thanks,
> -matt
>
>
>
>
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