llvm dev - Dec 2009 - [LLVMdev] A question about 'llc -march=c'

Hello friends working on LLVM,
I am a beginner to LLVM. I tried to get C code from LLVM bitcode using
'llc -march=c'. But it seems to me that it doesn't work if the
source
program is a C++ program. Am I right? I have attatched the source
program and the result of compiling the C code of it with GCC4.3.3. 
By the way, has LLVM's C code backend been tested on benchmarks like
spec?  Sorry if I missed the answers on websites.

Best regards,
Liang Peng
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$gcc testcc.cbe.c
testcc.cbe.c:323: warning: conflicting types for built-in function ‘malloc’
testcc.cbe.c: In function ‘main’:
testcc.cbe.c:356: warning: return type of ‘main’ is not ‘int’
/tmp/ccDcoA7R.o: In function `main':
testcc.cbe.c:(.text+0x33): undefined reference to `std::cout'
testcc.cbe.c:(.text+0x38): undefined reference to `std::basic_ostream<char,
std::char_traits<char> >& std::__ostream_insert<char,
std::char_traits<char> >(std::basic_ostream<char,
std::char_traits<char> >&, char const*, int)'
testcc.cbe.c:(.text+0x42): undefined reference to `std::cout'
testcc.cbe.c:(.text+0x47): undefined reference to `std::basic_ostream<char,
std::char_traits<char> >& std::endl<char,
std::char_traits<char> >(std::basic_ostream<char,
std::char_traits<char> >&)'
/tmp/ccDcoA7R.o: In function `global constructors keyed to main':
testcc.cbe.c:(.text+0x6a): undefined reference to
`std::ios_base::Init::Init()'
/tmp/ccDcoA7R.o: In function `__tcf_0':
testcc.cbe.c:(.text+0x9e): undefined reference to
`std::ios_base::Init::~Init()'
collect2: ld returned 1 exit status

Hello
> 'llc -march=c'. But it seems to me that it doesn't work if the
source
> program is a C++ program. Am I right?
No. You haven't linked libstdc++ in your case. So, you either have to
provide -lstdc++ or link via g++.

-- 
With best regards, Anton Korobeynikov
Faculty of Mathematics and Mechanics, Saint Petersburg State University

lpeng <pengliang at ict.ac.cn> writes:
> Hello friends working on LLVM,
> I am a beginner to LLVM. I tried to get C code from LLVM bitcode using
> 'llc -march=c'. But it seems to me that it doesn't work if the
source
> program is a C++ program. Am I right?
If you use functions from some library on your C++ code (the C++
Standard Library, for example) calls to those functions are still
present on the generated C code. This means that you must provide the
referenced library on your compile command.

On your case, either compile with

gcc testcc.cbe.c -lstdc++

or with

g++ testcc.cbe.c

(g++ automatically adds the C++ standard library)

[snip]

-- 
Óscar

Hi,
You need to link against the c++ standard library.
gcc test.cbe.c -lstdc++
works for me :)
Cornelius
Am 08.12.2009 10:00, schrieb lpeng:
> Hello friends working on LLVM,
> I am a beginner to LLVM. I tried to get C code from LLVM bitcode using
> 'llc -march=c'. But it seems to me that it doesn't work if the
source
> program is a C++ program. Am I right? I have attatched the source
> program and the result of compiling the C code of it with GCC4.3.3.
> By the way, has LLVM's C code backend been tested on benchmarks like
> spec?  Sorry if I missed the answers on websites.
>
> Best regards,
> Liang Peng
>
>
>
> _______________________________________________
> LLVM Developers mailing list
> LLVMdev at cs.uiuc.edu         http://llvm.cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev

Thank you very much! It works now with -lstdc++. 
And I still yearn to know whether LLVM's C code backend have been tested
on benchmarks like spec. :)

Best regards
Liang Peng