Path: utzoo!utgpu!water!watmath!clyde!bellcore!decvax!purdue!umd5!trantor.umd.edu!chris
From: chris@trantor.umd.edu (Chris Torek)
Newsgroups: comp.lang.c
Subject: Re: parameter adjustment (was double indirection)
Message-ID: <2305@umd5.umd.edu>
Date: 16 Feb 88 14:08:00 GMT
References: <4292@rosevax.Rosemount.COM> <2292@umd5.umd.edu> <16940@watmath.waterloo.edu>
Sender: ris@umd5.umd.edu
Reply-To: chris@trantor.umd.edu (Chris Torek)
Organization: University of Maryland, College Park
Lines: 27

In article <16940@watmath.waterloo.edu> rbutterworth@watmath.waterloo.edu
(Ray Butterworth) writes:
>C performs this "helpful" adjustment of the programmer's
>misdeclaration with other parameters too. ...
>sizeof args:   float=8  double=8  short=2  char=1  int[10]=4
>sizeof autos:  float=4  double=8  short=2  char=1  int[10]=40
>
>The "40" vs. the "4" shows the array parameter "adjustment".

This one is `correct' according to the language definition;

>And (float) is similarly adjusted form 4 to 8, since it is
>actually passed as (double).

but this one is just a bug.

Vax PCC could get away without the internal adjustment, since the Vax's
float and double (F and D floating, not G and H) types are `compatible'.
That is, double just adds more mantissa bits.  Other compilers might
have to generate a `virtual local float', something like:

	f(x) float x; { ... }
becomes: f(_arg_x) double _arg_x; { float x = _arg_x; ... }
-- 
In-Real-Life: Chris Torek, Univ of MD Computer Science, +1 301 454 7163
(hiding out on trantor.umd.edu until mimsy is reassembled in its new home)
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