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. -- Alan Modra Australia Development Lab, IBM
