From mboxrd@z Thu Jan  1 00:00:00 1970
To: 9fans@cse.psu.edu
From: Ralph Corderoy <ralph@inputplus.co.uk>
Message-ID: <3659.3d3887d9.c4bf1@blake.inputplus.co.uk>
References: <200207191253.NAA06845@cthulhu.dircon.co.uk>, <200207191541.g6JFfXMN025116@ducky.net>
Subject: Re: [9fans] useful language extension, or no?
Date: Mon, 29 Jul 2002 16:01:13 +0000
Topicbox-Message-UUID: d53f74a8-eaca-11e9-9e20-41e7f4b1d025

Hi Mike,

> The alternative to the trampoline would be for "pointer to function"
> to become a two-word object, or a pointer to a two-word object, with a
> changed calling sequence in either case.  This would be fine, the C
> standard would certainly allow it, but it would be binary incompatible
> with existing calling conventions in most systems.

Under IBM's AIX a pointer to function is the address of three words.

    Entry point of function's code.
    Address of module's Table of Contents.
    Used by some languages' implementations, OCS Ada for one IIRC.

So they went for the `function pointer fits into long' solution to avoid
breakage.

Cheers,


Ralph.