[LLVMdev] fPIC in llvm 2.6

[John Criswell]

  On 10/4/10 2:16 AM, Ryan M. Lefever wrote:
> It appears that llvm-ld can handle bitcode files but llvm-gcc complains
> that when I pass bitcode files to it.  I assume that means that llvm-gcc
> does not use llvm-ld by default.  Is there a way to force it to use llvm-ld?

One possibility is to use the gold linker as Bill was describing.  
Directions for Linux can be found at 
http://llvm.org/docs/GoldPlugin.html and 
http://llvm.org/docs/LinkTimeOptimization.html.

The directions may be incorrect in a few places; email llvmdev if you 
run into problems.

-- John T.

> Bill Wendling wrote:
>> You do it by using the -flto flag. But you will need a linker that's able to handle the bitcode files. The Apple linker can and so can the "gold" linker.
>>
>> -bw
>>
>> On Oct 3, 2010, at 7:47 PM, Ryan M. Lefever wrote:
>>
>>> The reason I was linking via llvm-ld is because I didn't know how to
>>> pass bitcode files to llvm-gcc.  How can I do that?
>>>
>>> Anton Korobeynikov wrote:
>>>>> Is fPIC broken on x86_64 in LLVM 2.6?
>>>> No, it works w/o any problems
>>>>
>>>>> -------------------
>>>>>> llvm-gcc -Iinclude -emit-llvm -fPIC -O3 -c -o file.opt.bc  file.c
>>>>>> llvm-ld -native -Xlinker=-shared -Xlinker=-Wl,-soname,libtest.so -o
>>>>> file.so file.opt.bc
>>>>> -------------------
>>>> PIC-ness is a backend option. So, passing -fPIC to llvm-gcc does not
>>>> make any sense, it is not saved into the bytecode.
>>>> Try passing -relocation-model=pic to llvm-ld, or just compile
>>>> everything via llvm-gcc which known how to pass necessary options to
>>>> backend :)
>>>>
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