Overmind Vs. Tyranid hive mind

[Tasoth]

Somehow, through the wonder of plot device, the Zerg and the Tyranid face off. During the conflict the Overmind and the Tyranid hive mind find each other. who wins?
Tyranid hive mind:
-Controls the billions of Tyranids scattered acrossed space.
-Uses Synapse creatures to exert its control over the lesser tyranid creatures in the battlefield.
-Exerts a 'Shadow in the Warp', rendering astropathic communication impossible, warp travel extremely dangerous and blots out the astronomicon.
-Is the reason the tyranids of psyker powers.
Overmind:
-Controls all them zerg, no idea how many.
-Uses Overlords, Queens, Cerebrates to further its control.

Who takes it?

please fill free to fill in anything i missed.