Sven Tennie authored Aug 26, 2025 and Marge Bot committed Sep 19, 2025

Shift primops' results are only defined for shift amounts of 0 to word
size - 1. The approach is similar to testing div-like operations (which
have a constraint regarding zero operands.)

This was partly vibe coded (https://github.com/supersven/ghc/pull/1) but
then heavily refactored.