[PATCH] rtl-ssa: Don't leave NOTE_INSN_DELETED around

[Alex Coplan]

Hi,

This patch tweaks change_insns to also call ::remove_insn to ensure the
underlying RTL insn gets removed from the insn chain in the case of a
deletion.

This avoids leaving NOTE_INSN_DELETED around after deleting insns.

For movement, the RTL insn chain is updated earlier in change_insns with
the call to move_insn.  For deletion, it seems reasonable to do it here.

Bootstrapped/regtested on aarch64-linux-gnu in combination with the upcoming
aarch64 load pair pass, i.e.:
https://gcc.gnu.org/pipermail/gcc-patches/2023-October/633601.html
and all uncommitted prerequisites except for 6/11 i.e.:
https://gcc.gnu.org/pipermail/gcc-patches/2023-October/633349.html
which shows that 6/11 is no longer required in combination with this patch (as
expected).

Thanks,
Alex

gcc/ChangeLog:

        * rtl-ssa/changes.cc (function_info::change_insns): Ensure we call
        ::remove_insn on deleted insns.

diff --git a/gcc/rtl-ssa/changes.cc b/gcc/rtl-ssa/changes.cc
index b11a88e0919..d6874e5627c 100644
--- a/gcc/rtl-ssa/changes.cc
+++ b/gcc/rtl-ssa/changes.cc
@@ -732,7 +732,11 @@ function_info::change_insns (array_slice<insn_change *> 
changes)
       insn_change &change = *changes[i];
       insn_info *insn = change.insn ();
       if (change.is_deletion ())
-       remove_insn (insn);
+       {
+         if (rtx_insn *rtl = insn->rtl ())
+           ::remove_insn (rtl); // Remove the underlying RTL insn.
+         remove_insn (insn);
+       }
       else if (insn_info *placeholder = placeholders[i])
        {
          // Check if earlier movements turned a move into a no-op.