[VectorLegalizer] Expansion of CTLZ using CTPOP when possible
This patch avoids scalarization of CTLZ by instead expanding to use CTPOP (ref: "Hacker's Delight") when the necessary operations are available.
This also adds the necessary cost models for X86 SSE2 targets (the main beneficiary) to ensure vectorization only happens when its useful.
Differential Revision: https://reviews.llvm.org/D25910
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@286233 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed