commit 17f93c96ec6c1ed1f2bd39dcfd7e517eaa79df70
author Sanjay Patel <spatel@rotateright.com> Mon Oct 14 21:56:40 2019 +0000
committer Sanjay Patel <spatel@rotateright.com> Mon Oct 14 21:56:40 2019 +0000
tree 43ef1692f19f5a39e1ca669b9906e4dba420f14a
parent e122082aec0233446f11b4248ac3ae802b2cce8a

[InstCombine] fold a shifted bool zext to a select

For a constant shift amount, add the following fold.
shl (zext (i1 X)), ShAmt --> select (X, 1 << ShAmt, 0)

https://rise4fun.com/Alive/IZ9

Fixes PR42257.

Based on original patch by @zvi (Zvi Rackover)

Differential Revision: https://reviews.llvm.org/D63382

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@374828 91177308-0d34-0410-b5e6-96231b3b80d8