[PATCH] D111036: [GlobalISel] Combine G_UMULH x, (1 << c)) -> x >> (bitwidth - c)

[Jay Foad via Phabricator via llvm-commits]

foad added a comment.

> G_UMULH x, (1 << c)) -> x >> (bitwidth - c)

This doesn't work when c is 0 because you get an out of range shift. In general you need something like x >> 1 >> (bitwidth - 1 - c).


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  https://reviews.llvm.org/D111036/new/

https://reviews.llvm.org/D111036