Enable -flto for mingw

[Morilli]

I noticed that the makefile contains this suspicious line: Link Time Optimization, it works since gcc 4.5 but not on mingw under Windows.. As I have compiled numerous software with link-time optimization enabled, I can assure it does work on mingw. I have found this previous issue #392, which is almost 5 years old by now and must be outdated. I'd like for someone to confirm that -flto does work on windows with mingw so it can be enabled in the makefile.

[vondele]

This should really work, and I think the comment is an old left-over.
It is also what we advertise here:
https://github.com/glinscott/fishtest/wiki/Building-stockfish-on-Windows#build-stockfish
Just verify this works, for you, and let us know. We'll fix-up the comment later.

[Morilli]

I have definitely tested it and it does work. I can launch the executable just fine and it's a little smaller than without -flto.

[vondele]

OK, I've removed the comment as part of #2695
Thanks for reporting.

[Morilli]

Shouldn't the actual code be adjusted as well? Because currently when using COMP=mingw -flto will not be set.

[vondele]

Ah sorry, I understood that the code worked as if. Can you show the changes you made to the Makefile? (git diff)

[Morilli]

Had actually just hacked that in before, but I think this should work:
mingw_diff.txt

edit: looking at it again, i'm not even sure the ifeq is even still necessary now, unless there is a 4th (or more?) supported options for COMP.

[abdulbadii]

@Morilli Why doesn't it works on my Mingw64 updated latest ?

[Morilli]

Uhm I cannot tell why it doesn't work for you, both build and profile-build work with -flto for me.

[abdulbadii]

running abruptly breaks, only build succeeds

[unaiic]

@Morilli Does it work now as it is in #2763?