tree 51c83ba471628a2da07a7b87ad6f924de5d0a07a
parent 8950d0a1f0620bb11f049dcdafb2b257c3c91d8f
author Sanjay Patel <spatel@rotateright.com> 1561415726 +0000
committer Sanjay Patel <spatel@rotateright.com> 1561415726 +0000

[InstCombine] squash is-not-power-of-2 using ctpop

This is the Demorgan'd 'not' of the pattern handled in:
D63660 / rL364153

This is another intermediate IR step towards solving PR42314:
https://bugs.llvm.org/show_bug.cgi?id=42314

We can test if a value is not a power-of-2 using ctpop(X) > 1,
so combining that with an is-zero check of the input is the
same as testing if not exactly 1 bit is set:

(X == 0) || (ctpop(X) u> 1) --> ctpop(X) != 1

llvm-svn: 364246