Reapply r233062: "float2int": Add a new pass to demote from float to int where possible.

Now with a fix for PR23008 and extra regression test.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@233175 91177308-0d34-0410-b5e6-96231b3b80d8
9 files changed