Craig Topper 233def40f7 [DAGCombiner] Prevent unfoldMaskedMerge from creating an AND with two inverted inputs. ...

It's possible that the mask is already a NOT. At least if InstCombine
hasn't canonicalized the input. In that case we will form an ANDN with
X instead of with Y. So we don't need to worry about Y being a constant.

We might need to check that X isn't a constant instead, but we don't
have a test case for that yet.

This fixes a size regression found when trying to enable this combine
for RISCV in D113937.

Differential Revision: https://reviews.llvm.org/D113948

2021-11-15 17:15:51 -08:00

912 KiB

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