Recommit r171461 which was incorrectly reverted. Mark DIV/IDIV instructions hasSideEffects=1 because they can trap when dividing by 0. This is needed to keep early if conversion from moving them across basic blocks.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@171608 91177308-0d34-0410-b5e6-96231b3b80d8