ARM: Fix crash in ARM backend inside of ARMConstantIslandPass

The ARM backend did not expect LDRBi12 to hold a constant pool operand.
Allow for LLVM to deal with the instruction similar to how it deals with
LDRi12.

This fixes PR16215.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183238 91177308-0d34-0410-b5e6-96231b3b80d8
IndVarSimplify: check if loop invariant expansion can trap

IndVarSimplify is willing to move divide instructions outside of their
loop bodies if they are invariant of the loop.  However, it may not be
safe to expand them if we do not know if they can trap.

Instead, check to see if it is not safe to expand the instruction and
skip the expansion.

This fixes PR16041.

Testcase by Rafael Ávila de Espíndola.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@183239 91177308-0d34-0410-b5e6-96231b3b80d8