[PATCH] D69127: [DAGCombiner] widen zext of popcount based on target support

[Sanjay Patel via Phabricator via llvm-commits]

spatel added a comment.

In D69127#1715640 <https://reviews.llvm.org/D69127#1715640>, @spatel wrote:

> This patch would already have hoisted the zext ahead of the i32 ctpop in that basic example, but if we had started with this i32 code, then we'd widen to i64 ctpop because we assume it's no more expensive than i32 ctpop+zext. For the PPC examples, the zext becomes a mask op, so we eliminate that instruction.


Oops - that last part was wrong. (And there's already a test for i32 -> i64.) Since PPC has legal ops for both types, we won't do anything for that pattern.


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  https://reviews.llvm.org/D69127/new/

https://reviews.llvm.org/D69127