NetBSD/sun3 9.0_STABLE GENERIC hang

I wrote on port-sun3@:

> - (Not Xserver related) recent netbsd-9 GENERIC kernel doesn't work?
>   NetBSD-daily/netbsd-9/202007161930Z one hangs just after
>   "enabling interrupts" message

By dumb manual bisect, it turns out this problem is caused by
recent src/sys/dev/scsipi/scsiconf.c pullup:

 https://mail-index.netbsd.org/source-changes/2020/07/13/msg119325.html
 > Continue scanning a SCSI bus when a LUN is reported not present

--- src/sys/dev/scsipi/scsiconf.c 2020/05/04 13:50:07 1.284.4.1
+++ src/sys/dev/scsipi/scsiconf.c 2020/07/13 14:09:10 1.284.4.2
@@ -887,6 +887,8 @@
 		break;
 
 	case SID_QUAL_LU_NOTPRESENT:
+		docontinue = 1;
+		/* FALLTHROUGH */
 	case SID_QUAL_reserved:
 	case SID_QUAL_LU_NOT_SUPP:
 		goto bad;

Adding printf before the "/* FALLTHROUGH */" line also solves the issue,
so it looks caused by gcc bug, and actually depends on COPTS:
-Os NG   (note sun3 uses -Os by default even for GENERIC)
-O0 OK
-O1 OK
-O2 OK
-O2 -fno-reorder-blocks OK
-Os -freorder-blocks NG
-Os -freorder-blocks -freorder-blocks-algorithm=stc OK
-Os -freorder-blocks-algorithm=stc OK
-Os -fno-reorder-blocks OK

Does anyone see the similar problem on other m68k ports?
(especially on INSTALL kernels built with -Os)

---
Izumi Tsutsui