On 08/20/2014 08:22 AM, Wilco Dijkstra wrote: > 2. Change the mid-end to call <arch>_frame_pointer_required even when > !flag_omit_frame_pointer.
Um, it does that already. At least as far as I can see from ira_setup_eliminable_regset and update_eliminables. It turns out to be much easier to re-enable a frame pointer for a given function than to disable a frame pointer. Thus I believe that you should approach -momit_leaf_frame_pointer as setting flag_omit_frame_pointer, and then re-enabling it in frame_pointer_required. This requires more than one line in common/config/arch/arch.c, but it shouldn't be much more than ten. > A second issue with frame pointers is that update_eliminables() in reload1.c > might set > frame_pointer_needed to false without any checks. How? I don't see that path, since the very first thing update_eliminables does is call frame_pointer_required -- even before it calls can_eliminate. Incidentally, I was working on exactly this (plus improving the unwind info) before I left on vacation a couple weeks ago. Note that you'll also need to remove x29 from the fixed registers before eliminating the frame pointer does any real good. r~
