From: Ralf Gütlein <ralf.guetlein@aranea.de>
To: "Bill Knight" <BillK@rosw.com>, "gcc" <gcc@gcc.gnu.org>,
"gnuh8" <gnuh8@pcserv.demon.co.uk>
Subject: Re: h8300: less optimal (buggy?) compiler output with last build
Date: Thu, 17 Aug 2000 02:36:00 -0000 [thread overview]
Message-ID: <03f401c0082e$82ec0e80$650b0d0a@Alzenau> (raw)
In-Reply-To: <200008161601.LAA05198@mail.teleteam.net>
----- Original Message -----
From: Bill Knight <BillK@rosw.com>
To: gcc <gcc@gcc.gnu.org>; gnuh8 <gnuh8@pcserv.demon.co.uk>
Sent: Wednesday, August 16, 2000 6:01 PM
Subject: Re: h8300: less optimal (buggy?) compiler output with last build
> The compiler may be trying to "help" because of the implied
> int declaration of Watchdog(). You might try the following
> declaration for Watchdog() and recheck the results:
>
> inline void Watchdog(void)
> {
> TCW = 0;
> }
>
One more typo in the rendering. My sources were correct, though...
To sum it up:
The compiler generates an unneccessary (and thus erroneous, even dangerous)
read acccess to a previously written location, if all of the following
conditions are true:
1) the object is volatile
2) the object is written to by an inline function
3) this inline function is called
example source (hopefully without typos ;-)
///////////////////////////////////////
extern volatile unsigned char TCW;
extern inline void WD(void)
{
TCW = 0;
}
void test(void)
{
WD();
}
///////////////////////////////////////
> >
> >Is this issue present in other ports?
This question has been answered already: yes!
> >Will this be investigated by somebody?
> >Or, could anybody give hints where to look for this issue in the sources?
These questions are still to be answered :-(
Regards,
Ralf
next parent reply other threads:[~2000-08-17 2:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <200008161601.LAA05198@mail.teleteam.net>
2000-08-17 2:36 ` Ralf Gütlein [this message]
2000-08-18 1:47 ` Ralf Gütlein
2000-08-16 8:21 Kazu Hirata
2000-08-16 9:00 ` Ralf Gütlein
2000-08-16 9:24 ` Alan Lehotsky
2000-08-18 5:45 ` Kai Ruottu
2000-08-21 7:36 ` Jeffrey A Law
-- strict thread matches above, loose matches on Subject: below --
2000-08-16 7:20 Ralf Gütlein
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