[LLVMdev] JIT compiled intrinsics calls is call to null pointer

[Andrew MacPherson]

Hi Taco,

We had a similar issue where a math intrinsic was being converted to a call
to null and it turned out to be because the system didn't support the CPU
instructions for the operation so the intrinsic used a call to the library
function (pow in your case). However because we weren't expecting this math
function to be looked up by MCJIT in our
JITMemoryManager::getPointerToNamedFunction() we weren't making it
available and it was returning null.

Not sure if this is relevant to your case but maybe it'll help point you in
the right direction.

Cheers,
Andrew


On Wed, Sep 18, 2013 at 8:32 AM, Taco H. in den Bosch <taco at heddesit.nl>wrote:

>
> Hi everyone,
>
> I am trying to call an LLVM intrinsic (llvm.pow.f32), inserted with the
> following call:
>
> std::vector<llvm::Type *> arg_types;
> arg_types.push_back(llvm::Type::getFloatTy(context));
> auto function=llvm::Intrinsic::getDeclaration(module,
> llvm::Intrinsic::pow, arg_types);
> auto result=ir_builder->CreateCall(function, args);
>
> When I try to execute the code generated by the JIT compiler, I see that
> the intrinsic is not compiled into a math coprocessor instruction, but in a
> call to a null address:
>
> 002300B8  sub         esp,8
> 002300BB  movss       xmm0,dword ptr ds:[2300B0h]
> 002300C3  movss       dword ptr [esp+4],xmm0
> 002300C9  movss       xmm0,dword ptr ds:[2300B4h]
> 002300D1  movss       dword ptr [esp],xmm0
> 002300D6  call        00000000
> 002300DB  add         esp,8
> 002300DE  ret
>
> Is there anything special that I need to do in order to be able to call
> intrinsics, either in general or when JITting? I am either doing something
> wrong, or forgetting to do something, but I don't know what.
>
> I am working with a Visual Studio compiled version on Windows (x86).
>
> All hints will be appreciated, with kind regards,
>
> Taco H. in den Bosch.
>
>
>
>
>
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