diff --git a/gcc/config/aarch64/aarch64-ldp-fusion.cc b/gcc/config/aarch64/aarch64-ldp-fusion.cc index bbb95d6c820a99c8103284ab6a7dcc5b0e0c88f9..e3827e980107de8706f52db7456b2928c11ac32d 100644 --- a/gcc/config/aarch64/aarch64-ldp-fusion.cc +++ b/gcc/config/aarch64/aarch64-ldp-fusion.cc @@ -1693,6 +1693,30 @@ ldp_bb_info::fuse_pair (bool load_p, if (trailing_add) changes.safe_push (make_delete (trailing_add)); + else if ((writeback & 2) && !writeback_effect) + { + // The second insn initially had writeback but now the pair does not, + // need to update any nondebug uses of the base register def in the + // second insn. We'll take care of debug uses later. + auto def = find_access (insns[1]->defs (), base_regno); + gcc_assert (def); + auto set = dyn_cast<set_info *> (def); + if (set && set->has_nondebug_uses ()) + { + auto orig_use = find_access (insns[0]->uses (), base_regno); + for (auto use : set->nondebug_insn_uses ()) + { + auto change = make_change (use->insn ()); + change->new_uses = check_remove_regno_access (attempt, + change->new_uses, + base_regno); + change->new_uses = insert_access (attempt, + orig_use, + change->new_uses); + changes.safe_push (change); + } + } + } auto is_changing = insn_is_changing (changes); for (unsigned i = 0; i < changes.length (); i++)