[InstCombine] Add m_Negative pattern matching

Allows us to add non-uniform constant vector support for "X urem C -> X < C ? X : X - C, where C >= signbit."

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@324631 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed