https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69891
--- Comment #6 from Eric Botcazou <ebotcazou at gcc dot gnu.org> ---
> But the memset could be also SIBLING_CALL_P.
> Wouldn't it be better to change the else if to if, and add
> if (const_call) return;
> plus return to the end of mems_found == 1 then block? Then it would fall
> through to arbitrary other call handling.
That would unnecessarily add a wild read. So what about:
Index: dse.c
===================================================================
--- dse.c (revision 233545)
+++ dse.c (working copy)
@@ -2528,6 +2528,10 @@ scan_insn (bb_info_t bb_info, rtx_insn *
i_ptr = i_ptr->next_local_store;
}
+ /* But a call to memset clobbers memory so invalidates stores. It's
+ not only an optimization issue (the previous stores may be dead)
+ but also a correctness issue since the previous stores cannot be
+ seen as the source of the current value of the locations. */
if (memset_call)
{
rtx args[3];
@@ -2556,6 +2560,8 @@ scan_insn (bb_info_t bb_info, rtx_insn *
active_local_stores = insn_info;
}
}
+ else if (!SIBLING_CALL_P (insn))
+ reset_active_stores ();
}
}
else if (SIBLING_CALL_P (insn) && reload_completed)
