This reverts commit 6758d67942. An EXEC pair loses its mask provenance and falls into the raw high-word path. The saved all-ones high word then keeps waterfall branches true and wedges GPU work.
6758d67942
* shader: preserve raw VCC bits in S_MOV_B64 * fix(shader): centralize scalar U64 mask provenance --------- Co-authored-by: nmzik <Nmzik@mail.ru>
nmzik