This is an updated version of the patch that was checked in at:
but subsequently reverted because it exposed the bug in:
This time I've put an enablement flag ("EnableFMFInDAG") around the code in SelectionDAGBuilder where we copy the set of FP optimization flags from IR instructions to DAG nodes. So, in theory, there should be no functional change from this patch as-is, but it will allow testing with the added functionality to proceed via "-enable-fmf-dag" passed to llc. So for example the testcase in D9893 should be fine by default and crash with FMF enabled.
This patch is derived from part of D8900.