From: Richard Henderson <rth@cygnus.com>
To: Martin von Loewis <martin@mira.isdn.cs.tu-berlin.de>, rth@cygnus.com
Cc: carlo@runaway.xs4all.nl, egcs-bugs@cygnus.com,
pommnitz@darmstadt.gmd.de, egcs@cygnus.com
Subject: Re: Further observations regarding alloca on i586-pc-linux-gnu
Date: Sun, 23 Aug 1998 18:49:00 -0000 [thread overview]
Message-ID: <19980823155704.C4163@dot.cygnus.com> (raw)
In-Reply-To: <199808231820.UAA00204@mira.isdn.cs.tu-berlin.de>
On Sun, Aug 23, 1998 at 08:20:05PM +0200, Martin von Loewis wrote:
> > Note that the exact same effect would happen if alloca was not a
> > builtin.
>
> No, it wouldn't. The portable alloca would not reclaim the memory
> until the next alloca call, and then only if the previous call was
> deeper on stack.
No no, I meant the olde tyme non-portable alloca. You know:
alloca: popl %edx
subl %eax, %esp
movl %esp, %eax
jmp *%edx
> > Note that if you mind sequence points like you ought, you get
> > correct results.
>
> The original example was using alloca as a default argument. It seems
> that g++ currently does not support that, an alloca call must occur as
> a full expression in itself, not inside a full expression.
"Full expression" isn't a term I'm familiar with. Besides,
(tmp = alloca(n), foo(tmp, blah));
works just fine. It seems that alloca must be the first thing
after a sequence point. How to enforce or even warn about this
I have absolutely no idea.
r~
next prev parent reply other threads:[~1998-08-23 18:49 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
1998-08-20 9:09 Joerg Pommnitz
1998-08-21 8:17 ` Noel Yap
1998-08-21 16:30 ` Alexandre Oliva
1998-08-22 11:00 ` Carlo Wood
1998-08-23 4:36 ` Richard Henderson
1998-08-23 12:13 ` Martin von Loewis
1998-08-23 18:49 ` Richard Henderson [this message]
1998-08-25 19:31 ` Martin von Loewis
1998-08-24 4:37 ` Jeffrey A Law
1998-08-25 7:28 ` Martin von Loewis
1998-08-24 10:48 ` Joerg Pommnitz
1998-08-25 12:45 ` Martin von Loewis
1998-08-25 19:31 ` Joerg Pommnitz
1998-08-25 19:31 ` Martin von Loewis
1998-08-25 23:05 ` signal 11 generating problem, was: " Joerg Pommnitz
1998-08-25 19:31 ` Alexandre Oliva
1998-08-25 19:31 ` Joerg Pommnitz
1998-08-25 23:05 ` Martin von Loewis
1998-08-26 8:25 ` Joe Buck
1998-08-26 5:20 ` Noel Yap
1998-08-26 11:57 ` Joe Buck
1998-08-26 3:53 ` Andreas Schwab
1998-08-26 12:26 ` Oleg Zabluda
1998-08-27 13:38 ` Alexandre Oliva
1998-08-25 19:31 ` Richard Henderson
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