pkg/55844: siag in misc/siag causes SIGSEGV with SSE2 on i386, using gcc10, egon also has SIGSEGV

[jbryn%students.wcpss.net@localhost]

>Number:         55844
>Category:       pkg
>Synopsis:       siag in misc/siag causes SIGSEGV with SSE2 on i386, using gcc10, egon also has SIGSEGV
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sat Dec 05 09:55:00 +0000 2020
>Originator:     Jackson Bryn
>Release:        NetBSD-current 9.99.76, pkgsrc/current 12/5/20
>Organization:
N/A
>Environment:
NetBSD build.localdomain 9.99.76 NetBSD 9.99.76 (Generic) #0: Mon Nov 30 07:53:42 UTC 2020  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/i386/compile/GENERIC i386
>Description:
Tested on a Haswell CPU in 32-bit mode, -march=bonnell, -mtune=bonnell, -O2, and -pipe.

While the crash in siag is fixable (disable SSE2 with -mno-sse2), the crash in egon is unknown. It can't be fixed with -O0 and -march/mtune=i486, nor does -fno-toplevel-reorder and -fcommon fix it.
>How-To-Repeat:
1. Launch siag on an SSE2 build and enter a value.
2. Launch egon.
>Fix: