Path: utzoo!utgpu!watserv1!watmath!att!linac!pacific.mps.ohio-state.edu!zaphod.mps.ohio-state.edu!rpi!sci.ccny.cuny.edu!phri!cmcl2!adm!smoke!gwyn
From: gwyn@smoke.brl.mil (Doug Gwyn)
Newsgroups: comp.lang.c
Subject: Re: Compiler bug or gray area in C?
Keywords: register floating point optmization
Message-ID: <14609@smoke.brl.mil>
Date: 29 Nov 90 20:05:16 GMT
References: <1990Nov28.220233.2630@ingres.Ingres.COM> <1990Nov29.021553.12522@ingres.Ingres.COM>
Organization: U.S. Army Ballistic Research Laboratory, APG, MD.
Lines: 14

In article <1990Nov29.021553.12522@ingres.Ingres.COM> jeff@ingres.com (Jeff Anton) writes:
>The issue is the legality of compilers extending the precision of
>variable when they are placed in registers.

In many environments there is no choice; floating registers simply ARE
wider than floating storage.

The issue of exactly when an implementation is obliged to "scrape off"
the extra precision is still open in X3J11, if I recall correctly.  One
might think that any cast or assignment should do this, but there are
arguments why that isn't always desirable.  At this point there is a C
standard and it is "just" a matter of interpreting what requirements, if
any, it imposes in this area.  There should be an official interpretation
ruling on this sometime..