[TargetLowering] Generalise BuildSDIV function

First step towards a BuildSDIV equivalent to D49248 for non-uniform vector support - this just pushes the splat detection down into TargetLowering::BuildSDIV where its still used.

Differential Revision: https://reviews.llvm.org/D50185

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@338838 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed