[LLVMdev] Calling functions defined in .o files in LLVM code executed in lli

[Vikram S. Adve]

Assuming the run-time library is in C, is there a reason why you  
cannot also compile that to LLVM?  You could get significantly better  
optimization via LTO that way.

--Vikram
http://www.cs.uiuc.edu/~vadve
http://llvm.org


On Dec 8, 2007, at 12:12 AM, Chris Lattner wrote:

>
> On Dec 7, 2007, at 6:38 AM, John van Schie wrote:
>
>> Hi,
>>
>> This is probably an easy question, but I could not find the answer
>> to it.
>>
>> I'm working on a LLVM back-end for the EHC compiler (a Haskell
>> compiler). Currently there is a C back-end and I would like to reuse
>> the
>> primitive library functions from this back-end.
>
> Ok.
>>
>
>> So I have compiled C sources in a .o file and I would like to call
>> these
>> from my LLVM code. If I declare these primitive functions in the LLVM
>> code and link the bitcode file and the .o file with llvm-ld it works
>> only if I generate native code. If I omit the -native flag to llvm-ld
>> and execute the generated shell script a.out I get the following
>> error:
>>
>> glimi at brodie:~$ llvm-ld ../../prim.o TestExist.bc && ./a.out
>
> This fails because "a.out" is a shell script that is invoking the JIT.
>
>> Is there a way to link the functions declared in the .o file in the
>> bitcode without compiling the C sources with llvm-gcc?
>
> Yes, certainly.  If you want the JIT to work, you need to link your .o
> files together into a .so/.dylib file, then use the 'lli -load
> foo.dylib' option to load it.  If you want to natively link your
> application together, just toss your .o files on the native link line.
>
> -Chris
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