[LLVMdev] How to get llvm bitcode executed

[Xiaolong Tang]

Thanks Duncan and Ashok, 

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

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
> > _______________________________________________
> > LLVM Developers mailing list
> > LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev
> 
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