Path: news.eternal-september.org!eternal-september.org!.POSTED!not-for-mail
From: Thomas Koenig <tkoenig@netcologne.de>
Newsgroups: comp.arch
Subject: Re: Split instruction and immediate stream
Date: Sun, 9 Mar 2025 19:38:46 -0000 (UTC)
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MitchAlsup1 <mitchalsup@aol.com> schrieb:
> On Sun, 9 Mar 2025 12:03:22 +0000, Robert Finch wrote:
>
>>>
>> One thought I had a while ago using a similar technique to glyph's was
>> to place constants at the beginning or the end of a cache line. Then the
>> immediate base register is not needed. The relative offsets would be in
>> terms of the current cache line. It has a couple of drawbacks though,
>> one being the need to branch around the constant data; could be done by
>> carefully maintaining the next fetch address. Another drawback is the
>> code is repositionable only at cache-line boundaries. Might make
>> assembling / linking code interesting.
>
> If you put the constants at the end of the cache line, you will have
> accessed the constants while decoding the instructions and you can
> figure out when to jump to the next cache line without branching.

Did I mention I would not like to write an assembler for that? :-)