[ARM] Allow half types in ConstantPool

Change ARMConstantIslandPass to:
- accept f16 literals as litpool entries,
- if the litpool needs to be inserted in the middle of a big block, then we
  need to 4-byte align the next instruction in ARM mode.

Differential Revision: https://reviews.llvm.org/D42784


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@325012 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed