tree ce1b4a9ba2a453ef9972b0a1e18ba7e31fab41df
parent 21d8f66d20b813edadac84b12cc83b66eaeae630
author Craig Topper <craig.topper@intel.com> 1593888120 -0700
committer Craig Topper <craig.topper@intel.com> 1593888173 -0700

[DAGCombiner] Don't fold zext_vector_inreg/sext_vector_inreg(undef) to undef. Fold to 0.

zext_vector_inreg needs to produces 0s in the extended bits and
sext_vector_inreg needs to produce upper bits that are all the
same. So we should fold them to a 0 vector instead of undef.

Fixes PR46585.