[llvm-commits] [llvm] r154124 - /llvm/trunk/tools/lto/LTOCodeGenerator.cpp

[Bill Wendling]

On Apr 9, 2012, at 3:09 PM, Rafael Espíndola <rafael.espindola at gmail.com> wrote:

>> Consider the following program:
>> 
>> $ cat main.c
>> void foo(void) { }
>> 
>> int main(int argc, char *argv[]) {
>>    foo();
>>    return 0;
>> }
>> $ cat bundle.c
>> extern void foo(void);
>> 
>> void bar(void) {
>>     foo();
>> }
>> $ clang -o main main.c
>> $ clang -o bundle.so bundle.c -bundle -bundle_loader ./main
>> $ nm -m bundle.so
>> 0000000000000f40 (__TEXT,__text) external _bar
>>                 (undefined) external _foo (from executable)
>>                 (undefined) external dyld_stub_binder (from libSystem)
>> $ clang -o main main.c -O4
>> $ clang -o bundle.so bundle.c -bundle -bundle_loader ./main
>> Undefined symbols for architecture x86_64:
>>  "_foo", referenced from:
>>      _bar in bundle-elQN6d.o
>> ld: symbol(s) not found for architecture x86_64
>> clang: error: linker command failed with exit code 1 (use -v to see invocation)
> 
> Note that I get exactly the same error with:
> 
> $ clang -o main main.c -Wl,-dead_strip -O3
> $ clang -o bundle.so bundle.c -bundle -bundle_loader ./main
> Undefined symbols for architecture x86_64:
>  "_foo", referenced from:
>      _bar in bundle-LRWElp.o
> ld: symbol(s) not found for architecture x86_64
> clang-3: error: linker command failed with exit code 1 (use -v to see
> invocation)
> 
> Which shows that the problem is *not* with us running internalize, it
> is with the linker telling us the foo is not needed.
> 

This has nothing to do with my changes:

[bwendling:llvm] clang -O3 -Wl,-dead_strip a.c
[bwendling:llvm] nm -m a.out
0000000100000000 (__TEXT,__text) [referenced dynamically] external __mh_execute_header
0000000100000f70 (__TEXT,__text) external _main
                 (undefined) external dyld_stub_binder (from libSystem)

-bw