[LLVMdev] strace for whole-program bitcodes

[Rafael Espindola]

2009/10/19 zhunan <zhunansjtu at gmail.com>:
> Yes,but when I just simply replace lto_codegen_compile(cg, ...) with
> lto_codegen_write_merged_modules(cg, "/path/to/output.bc") in the
> gold-plugin.cpp to see if it will generate a correct bc file,the
> llvm-gcc/llvm-g++ will call the native ld in the linking step,which
> causes the failture because of that ld can not recognize an object file
> which contains LLVM's IL.

The plugin is running *in* the native linker. What you want to do is
add an option in the plugin to write the bc file to an specified file
*in addition* to producing a regular elf object. This way the build
will complete correctly and you will get the .bc file you want.

> I understand the failture as this: libLLVMgold.so is just a plugin for
> ld but not llvm-ld,when I want to build a whole-program bitcodes,llvm-ld
> is the only available tool,so I think gold-plugin is not very useful to
> archieve the goal,I'm considering to modify the codes of llvm-gcc's
> collect2 to make it call llvm-ld automatically when receive certain
> options.

It will probably be hard to get this to work correctly with archives
and shared libraries. In 4.5 gcc we have a hacked collect2 for
people using lto and gnu ld.

> Thanks
>

Cheers,
-- 
Rafael Ávila de Espíndola