[LLVMdev] undefined reference to 'llvm_gcda_start_file', 'llvm_gcda_emit_arcs', etc

Qun Fa testforqunfa at gmail.com
Thu Mar 14 14:36:49 PDT 2013

Hi All,

I think Nick's suggestion is correct, my code was linked against
libprofile_rt.a, which had gcda profiling code before, but was removed

So, I couldn't find the correct symbols from libprofile_rt.a any more.

Now my assumption is I need to use the correct library that is provided by
compiler-rt. May I know which one?

I am building the entire llvm/clang including compiler-rt based on the
instructions given on the clang get started page (
http://clang.llvm.org/get_started.html), but with CMake instead of
Makefile. But I also noticed in the compiler-rt/lib/CMakeLists.txt file, we
have the following FIXME.

# FIXME: Add support for the profile library.

So, if I want to use the correct library, do I have to switch to Makefile?
Any ideas?

Thanks very much,

On Thu, Mar 14, 2013 at 8:46 AM, Qun Fa <testforqunfa at gmail.com> wrote:

> Thanks for your reply.
> May I know which is the recommended library that should be linked against?
> I am currently linking libprofile_rt.a.
> And I have noticed the differences that, if we do
> `nm libprofile_rt.a | grep llvm`
> with my old copy of the llvm/clang installation, I can see
> 00000000000005e0 T _llvm_gcda_emit_arcs
> 0000000000000b48 S _llvm_gcda_emit_arcs.eh
> 0000000000000430 T _llvm_gcda_emit_function
> 0000000000000aa8 S _llvm_gcda_emit_function.eh
> 00000000000006c0 T _llvm_gcda_end_file
> 0000000000000b98 S _llvm_gcda_end_file.eh
> 00000000000003d0 T _llvm_gcda_increment_indirect_counter
> 0000000000000a80 S _llvm_gcda_increment_indirect_counter.eh
> 0000000000000000 T _llvm_gcda_start_file
> 0000000000000a08 S _llvm_gcda_start_file.eh
> They are the symbols that my test build is looking for.
> But with the latest codebase, here is what I saw
> 00000000000000a8 T llvm_start_basic_block_tracing
> 0000000000000067 T llvm_trace_basic_block
> 0000000000000467 T llvm_decrement_path_count
> 000000000000042a T llvm_increment_path_count
> 0000000000000662 T llvm_start_path_profiling
> 0000000000000020 T llvm_start_edge_profiling
> 0000000000000020 T llvm_start_opt_edge_profiling
> Thanks again,
> Qun
> On Thu, Mar 14, 2013 at 1:11 AM, Nick Lewycky <nicholas at mxc.ca> wrote:
>> Qun Fa wrote:
>>> Hi,
>>> I am trying to test my project and get the code coverage with a version
>>> of clang compiler that was built from the latest llvm/clang codebase.
>>> It worked for a while. But today, after I updated my local checkout, and
>>> re-build llvm, clang and compiler-rt, when I test my project again, I
>>> got the errors with undefined reference to 'llvm_gcda_start_file',
>>> 'llvm_gcda_emit_arcs', 'llvm_gcda_emit_function', and
>>> 'llvm_gcda_end_file'.
>>> I have searched the codebase, and have found the functions are defined
>>> in GCDAProfiling.c file, but not sure why this suddenly doesn't work for
>>> me.
>>> Anyone can give any suggestions?
>> Those symbols should be provided by compiler-rt/lib/profile/**GCDAProfiling.c.
>> There used to be a copy in llvm's tree, but I deleted that one recently.
>> It's possible you used to be using the one from llvm, but now need to
>> switch to using the one from compiler-rt?
>> Nick
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