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From: Joe Monk <joemonk64@gmail.com>
Date: Tue, 7 Sep 2021 02:21:21 -0500
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Subject: Re: s390 port
To: Paul Edwards <mutazilah@gmail.com>
Cc: "gcc@gcc.gnu.org" <gcc@gcc.gnu.org>
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It is unclear how this would even work.

For instance, the LA instruction clears the top bit.

Also, instructions like LPR, LNR, BXLE, BXH all treat the value in the
register as signed, so the top bit is not available.

Joe