WholeProgramDevirt: Create bitcast to i8* at each virtual call site.

We can't reuse the llvm.assume instruction's bitcast because it may not
dominate every user of the vtable pointer.

Differential Revision: https://reviews.llvm.org/D36994

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@311491 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed