[CLN-list] Linking against cln fails when built with link-time-optimization

[Richard B. Kreckel]

Hi Alexey,

On 21.10.20 10:45, Alexey Sheplyakov wrote:
> 1. Cross-module/whole program analysis (which is a proper name for LTO) is a well
>      established optimization method. And it's exactly the right way for the compiler
>      to know that
> 
>      a)  cl_{SF,FF,DF,LF}_idecode are called mostly by cl_F_idecode (so it's a good
>           idea to inline those 4 functions)
>      b) every cl_I is created through cl_I_from_NDS (so it's a good idea to inline cl_I_from_NDS)
> 
>       etc.
> 
> 2. Most (all?) major C++ compilers (GCC, clang, msvc) provide cross-module/whole program
>      analysis. In fact it has been available for (almost) two decades. LTO branch has been
>      merged into GCC trunk back in 2009. Link time code generation (which is msvc name
>      for cross-module analysis) has been available since visual studio 7.0 (released in 2002).
> 
> Therefore I prefer the "Stop playing tricks and use the LTO" solution.

We need evidence, please, and benchmarks!

I tried compiling CLN with -flto added to CXXFLAGS and it turned out my 
machine has too little memory (it has 32GiB).

It appears to me this isn't quite ready for showtime.

   -richy.
-- 
Richard B. Kreckel
<https://in.terlu.de/~kreckel/>