Subject: Re: -mregparm=X (for X > 0)
To: None <>
From: J.T. Conklin <>
List: port-i386
Date: 07/06/1995 12:08:01
> While poking through the info pages of gcc-2.7.0, I discovered the
> flag -mregparm=X for the i386.
> Has anyone thought of doing this?
> Any idea what kinda performance improvement we might see?

If I remember correctly, there was discussion on the gcc2 mailing list
about this feature when it was being considered.  I think the decision
to include it was made so that people could easily measure its effects.

I believe that some people did not want to provide command line
arguments, presumably because they didn't want to deal with bug
reports from people who tried to link code generated with different
calling conventions.

I'd guess that -mregparms improves performance in some instances, and
harms it in others.  It would be difficult to measure its effect over
an entire operating system.  I'd be much more likely to experiment
with it if I was writing code for an embedded platform.


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