[ARM] Place jump table as the first operand in additions

When generating table jump code for switch statements, place the jump
table label as the first operand in the various addition instructions
in order to enable addressing mode selectors to better match index
computation and possibly fold them into the addressing mode of the
table entry load instruction.

Differential revision: https://reviews.llvm.org/D39752


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@318033 91177308-0d34-0410-b5e6-96231b3b80d8
6 files changed