On Tue, May 19, 2015 at 9:09 PM, Alan Modra <amo...@gmail.com> wrote: > On Mon, May 18, 2015 at 02:05:59PM -0400, David Edelsohn wrote: >> On Sun, May 17, 2015 at 10:54 PM, Alan Modra <amo...@gmail.com> wrote: >> > This patch changes rs6000_stack_info to keep save areas offsets even >> > when not used. I need lr_save_offset valid for split-stack, and it >> > seemed reasonable to treat the other offsets the same. Not zeroing >> > the offsets requires just one change in code that uses them, the >> > use_backchain_to_restore_sp expression in rs6000_emit_epilogue, not >> > counting the debug_stack_info changes. >> > >> > * config/rs6000/rs6000.c (rs6000_stack_info): Don't zero offsets >> > when not saving registers. >> > (debug_stack_info): Adjust to omit printing unused offsets, >> > as before. >> > (rs6000_emit_epilogue): Adjust use_backchain_to_restore_sp >> > expression. >> >> I think that the vrsave_save_offset change may break saving of >> callee-saved VRs. See PR 55276. > > I checked. It doesn't break that testcase. PR 55276 was really > caused by using vrsave_mask for two purposes, firstly to track which > altivec registers have been saved, and secondly to control use of the > vrsave stack slot and whether mfvrsave/mtvrsave insns are generated. > Patch 2/4 removes this conflation.
Okay, but that confirms Patch 1 is not safe without the patch series. - David