Add early if-conversion support to X86.

Implement the TII hooks needed by EarlyIfConversion to create cmov
instructions and estimate their latency.

Early if-conversion is still not enabled by default.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@159695 91177308-0d34-0410-b5e6-96231b3b80d8
4 files changed