[DAG] Remove isVectorClearMaskLegal() check from vector_build dagcombine
This check currently doesn't seem to do anything useful on any in-tree target:
On non-x86, it always evaluates to false, so we never hit the code path that
creates the shuffle with zero.
On x86, it just forwards to isShuffleMaskLegal(), which is a reasonable thing to
query in general, but doesn't make sense if only restricted to zero blends.
Differential Revision: https://reviews.llvm.org/D24625
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@282567 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed