g++10 versus g++9

[xr_a_y]

is -45Elo for Minic ...

Does this happened to someone else ?
Any countermeasure (apart from falling back to gcc9)?

Thanks for your inputs !

[Pi4Chess]

Ouch

[Ras]

is -45Elo for Minic ...

How many games?

Does this happened to someone else ?

No, just checked at a thousand games. However, the GCC-10 generated binary is 4.5% faster for me.

Any countermeasure (apart from falling back to gcc9)?

Run your engine with a single worker thread. Use a few positions to calculate to some depth so that it takes at least 10 seconds. Check whether reported PV and node counts match for the binaries generated with GCC-9 and GCC-10. It's not uncommon for bugs to only manifest upon a compiler update.

[xr_a_y]

is -45Elo for Minic ...

How many games?

Does this happened to someone else ?

No, just checked at a thousand games. However, the GCC-10 generated binary is 4.5% faster for me.

Any countermeasure (apart from falling back to gcc9)?

Run your engine with a single worker thread. Use a few positions to calculate to some depth so that it takes at least 10 seconds. Check whether reported PV and node counts match for the binaries generated with GCC-9 and GCC-10. It's not uncommon for bugs to only manifest upon a compiler update.

1000 games, so accurate enough to be a real issue.

No difference in terms of nodes count (or any other statistic Minic is able to print), so no obvious bug.
But 10% lower nps.

Anyway Minic was always slow and affected by small changes. I guess there are too much bad design that the compiler cannot always handle easily and optimize. It's propably more on my side than one gcc.

[mar]

No difference in terms of nodes count (or any other statistic Minic is able to print), so no obvious bug.
But 10% lower nps.

10% lower nps - that's at most 10 elo at hyperbullet, realistically about 5.
so I wonder where you get -45 I suspect an issue with testing.

[syzygy]

is -45Elo for Minic ...

Does this happened to someone else ?
Any countermeasure (apart from falling back to gcc9)?

Add - O3 to the compiler flags. (Hopefully this is a stupid suggestion.)