[PATCH] D36351: [lld][ELF] Add profile guided section layout

[Michael Spencer via Phabricator via llvm-commits]

Bigcheese added a comment.

In https://reviews.llvm.org/D36351#956212, @ruiu wrote:

> > This needs to be implemented in the linker because of the line:
> > 
> >   if (From.Size + To.Size > Target->PageSize)
> >     continue;
> >    
> > 
> > This is responsible for doubling the performance improvement on a game. Implementing this outside of the linker requires implementing most of the linker, including LTO.
>
> And function sizes cannot be retrieved from the instrumented build (because instrumentation changes function size), so it must be computed at link-time. Is this correct?


An

In https://reviews.llvm.org/D36351#956212, @ruiu wrote:

> > This needs to be implemented in the linker because of the line:
> > 
> >   if (From.Size + To.Size > Target->PageSize)
> >     continue;
> >    
> > 
> > This is responsible for doubling the performance improvement on a game. Implementing this outside of the linker requires implementing most of the linker, including LTO.
>
> And function sizes cannot be retrieved from the instrumented build (because instrumentation changes function size), so it must be computed at link-time. Is this correct?


Yes.


https://reviews.llvm.org/D36351