[x86] allow single source horizontal op matching (PR39195)
This is intended to restore horizontal codegen to what it looked like before IR demanded elements improved in:
rL343727
As noted in PR39195:
https://bugs.llvm.org/show_bug.cgi?id=39195
...horizontal ops can be worse for performance than a shuffle+regular binop, so I've added a TODO. Ideally, we'd
solve that in a machine instruction pass, but a quicker solution will be adding a 'HasFastHorizontalOp' feature
bit to deal with it here in the DAG.
Differential Revision: https://reviews.llvm.org/D52997
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@344141 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed