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From: antispam@fricas.org (Waldek Hebisch)
Newsgroups: comp.arch
Subject: Re: Calling conventions (particularly 32-bit ARM)
Date: Thu, 16 Jan 2025 16:24:38 -0000 (UTC)
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MitchAlsup1 <mitchalsup@aol.com> wrote:
> On Thu, 16 Jan 2025 3:02:44 +0000, Waldek Hebisch wrote:
> 
>> MitchAlsup1 <mitchalsup@aol.com> wrote:
>>>
>>
>>> Pass by COMMON block was even faster.
>>
>> I do not think so.  I LAPACK-like cases there are array arguments.
>> Normal calling convention needs to store and later read parameters
>> and pass addresses.  COMMON would force copying of entire arrays,
>> much less efficienct than handling parameters.
> 
>       SUBROUTINE FOO
>       COMMON /ALPHA/ i,j,k,a[100],b[100],c[100,100]
> 
> See no arguments, passed directly by common-block, no copying of
> data, no dope vectors needed.

No copy only if there is single set of arguments.  If there are
different arguments, then one needs to pass them, that is copy
them.

-- 
                              Waldek Hebisch