On Thu, May 25, 2023 at 4:38 PM Jeff Law <jeffreya...@gmail.com> wrote: > > > > On 5/25/23 06:35, Manolis Tsamis wrote: > > Propagation of the stack pointer in cprop_hardreg is currenty forbidden > > in all cases, due to maybe_mode_change returning NULL. Relax this > > restriction and allow propagation when no mode change is requested. > > > > gcc/ChangeLog: > > > > * regcprop.cc (maybe_mode_change): Enable stack pointer > > propagation. > I can't see how this can be correct given the stack pointer equality > tests elsewhere in the compiler, particularly the various targets. > > The problem is if you change the mode then you end up with multiple REG > expressions that reference the stack pointer. > > See rev: d1446456c3fcaa7be628726c9de4a877729490ca and the thread around > the change which introduced this code. >
Hi Jeff, Isn't this fine for this case since: 1) stack_pointer_rtx is used which won't cause issues with pointer equalities (If I understand correctly). 2) Propagation is guarded with `if (orig_mode == new_mode)` so only when there is no mode change. Thanks, Manolis > > Jeff
