[LLVMdev] How to get llvm bitcode executed

[Duncan Sands]

Hi Xiaolong,

> As Duncan described, "lli -load=libstdc++.dylib ..." works. I,
> however, encounted an "Illegal instruction" message, while I was
> trying to interpret a large program.

are you using the interpreter or the JIT?

  So, does lli have a debug switch
> for dumping out the details for errors?
>
> Using llc is not that simple, and I have not gotten through the
> compilation process. For instance, "llc -o test.s test.bc" works and
> generates "test.s"; "g++ -o test.o test.s" throws out "Unknown
> pseudo-op: .cfi_startproc" messages, however. Not sure about the
> reasons yet.

This means that your binutils is too old.  Try passing -disable-cfi
to llc.

Ciao, Duncan.

>
> Xiaolong
>
>
>
> Duncan Sands wrote:
>>
>> Hi Xialong,
>>
>>> I have a program that uses C++ STL a lot. To have the source code for
>>> STL functions, I undefined "_GLIBCXX_EXTERN_TEMPLATE" in
>>> c++config.h. In spite of this, after compilation (via clang) and
>>> linking (via llvm-ld), the resulting bitcode contains a few declared
>>> functions (with no definitions).
>>>
>>> My question is: In the scenario where some function definitions are
>>> missing in a llvm bitcode, can we get a way to run this module via llc
>>> or lli? Or is there any way to make these function definitions
>>> available in the llvm bitcode?
>>
>> with lli, you should be able to do it by adding
>>     -load=libstdc++.so
>> to the lli command line (maybe with a full path).  With llc, use g++
>> to the linking.  For example, if llc turned bitcode.bc into bitcode.s,
>> do
>>     g++ -o bitcode bitcode.s
>> since g++ automagically passes libstdc++ to the linker.  You can also
>> use the system linker directly, adding the missing libraries.
>>
>>>
>>> Specifically, these missing functions are as below:
>>>
>>>     declare i8* @llvm.eh.exception() nounwind readonly
>>
>> This is an LLVM intrinsic, so isn't really missing.
>>
>>>     declare i32 @__gxx_personality_v0(...)
>>
>> This should be in libstdc++.
>>
>>>     declare i32 @llvm.eh.selector(i8*, i8*, ...) nounwind
>>>     declare void @llvm.eh.resume(i8*, i32)
>>
>> LLVM intrinsics.
>>
>>>     declare void @_ZSt9terminatev()
>>
>> This should be in libstdc++.
>>
>>>     declare i32 @memcmp(i8*, i8*, i64)
>>
>> In libc (libc.so) which should be pulled in by libstdc++.
>>
>>>     declare i64 @llvm.expect.i64(i64, i64) nounwind readnone
>>
>> LLVM intrinsic.
>>
>>>     declare void @_ZSt19__throw_logic_errorPKc(i8*) noreturn
>>>     declare i8* @__cxa_begin_catch(i8*)
>>>     declare void @__cxa_rethrow()
>>>     declare void @__cxa_end_catch()
>>>     declare void @__cxa_call_unexpected(i8*)
>>>     declare void @_ZdlPv(i8*) nounwind
>>>     declare void @_ZSt20__throw_length_errorPKc(i8*) noreturn
>>>     declare void @_ZSt17__throw_bad_allocv() noreturn
>>>     declare noalias i8* @_Znwm(i64)
>>
>> These should all be in libstdc++.
>>
>>>     declare void @llvm.memcpy.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
>>>     declare void @llvm.memmove.p0i8.p0i8.i64(i8* nocapture, i8* nocapture, i64, i32, i1) nounwind
>>>     declare i32 @llvm.atomic.load.add.i32.p0i32(i32* nocapture, i32) nounwind
>>>     declare void @llvm.memory.barrier(i1, i1, i1, i1, i1) nounwind
>>
>> LLVM intrinsics.
>>
>>>     declare void @_ZSt20__throw_out_of_rangePKc(i8*) noreturn
>>
>> This should be in libstdc++.
>>
>>>     declare i64 @strlen(i8*)
>>>     declare void @abort()
>>
>> In libc (libc.so) which should be pulled in by libstdc++.
>>
>> Ciao, Duncan.
>>
>>>
>>>
>>> Xiaolong
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>>> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
>>
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