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Groups > comp.lang.c++ > #68950
| From | Soviet_Mario <SovietMario@CCCP.MIR> |
|---|---|
| Newsgroups | comp.lang.c++, comp.lang.c |
| Subject | Re: alloca()-support |
| Date | 2019-10-03 13:39 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <qn4mlg$3f4$2@dont-email.me> (permalink) |
| References | (2 earlier) <qmtbqv$ttm$1@news.albasani.net> <qmtc2o$pmp$4@dont-email.me> <qmtc6v$uk5$1@news.albasani.net> <qmtfeh$gno$1@dont-email.me> <lRskF.22050$XA2.21391@fx05.iad> |
Cross-posted to 2 groups.
On 30/09/2019 21:38, Scott Lurndal wrote:
> Soviet_Mario <SovietMario@CCCP.MIR> writes:
>> On 30/09/2019 18:58, Bonita Montero wrote:
>>>>>> Since when (if at any time) was variable size automatic
>>>>>> array supported ?
>>>
>>>>> Since C99.
>>>
>>>> for curiosity, this feature has one or more of the
>>>> limitations I feared ... or even none of them ?
>>>
>>> Yes, you could run out of stack-space, maybe hitting a
>>> guard-page
>>> in the best case so that you wouldn't corrupt any other data.
>>
>> uhm, I didn't mean THAT kind of risk (unavoidable), but the
>> possible difficulties in defining variables beyond the point
>> of declaration of the variable-size array.
>>
>> I can't figure out how the compiler would reference them in
>> standard efficient ways (use of registers).
>
>
> mov %rsp, %rax # rax now has starting address of alloca() region
> sub %rcx, %rsp # rcx is the number of bytes being allocated.
>
> ....
>
> mov %rsp, %rbx # rbx now has starting address of second alloca() region
> sub %rdx, %rsp # rdx is the number of bytes being allocated
> ....
> ret # all alloca storage is deallocated
>
I guess this disassembly does not correspond with the
minimal example I asked for.
I actually do not have a compiler supporting this, so I
cannot try myself
the code I'd like to see in .asm intermediate code (NO
OPTIMIZATION ACTIVE) was
int Funz (int A, int B)
{
int C = 3;
int Buf [A];
int D = 2;
Buf [A-1] = B;
return (A + B * D - C);
}
int main (void)
{
return Funz (4, 3);
}
could you print the .asm generated for this, if your
compiler supports variable arrays on stack ?
TNX
> (AT&T form)
>
> It can always spill rax or rbx to the stack under register pressure.
>
--
1) Resistere, resistere, resistere.
2) Se tutti pagano le tasse, le tasse le pagano tutti
Soviet_Mario - (aka Gatto_Vizzato)
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alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 14:02 +0200
Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-09-30 07:02 -0700
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 16:09 +0200
Re: alloca()-support Bo Persson <bo@bo-persson.se> - 2019-09-30 17:29 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 17:33 +0200
Re: alloca()-support gazelle@shell.xmission.com (Kenny McCormack) - 2019-09-30 16:26 +0000
Re: alloca()-support Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-09-30 17:12 +0300
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 16:16 +0200
Re: alloca()-support Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-09-30 17:30 +0300
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 16:44 +0200
Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-02 00:36 +0300
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:28 +0200
Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-02 16:08 +0300
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 15:42 +0200
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 14:30 +0000
Re: alloca()-support Anton Shepelev <anton.txt@g{oogle}mail.com> - 2019-09-30 17:33 +0300
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-09-30 16:56 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-09-30 15:29 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 17:31 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-01 07:03 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 10:57 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-01 18:49 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 21:20 +0200
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-01 20:39 +0000
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:15 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:28 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:29 +0000
Re: alloca()-support Keith Thompson <kst-u@mib.org> - 2019-09-30 11:14 -0700
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 18:04 +0200
Re: alloca()-support William Ahern <william@25thandClement.com> - 2019-09-30 11:01 -0700
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:19 +0200
Re: alloca()-support Paavo Helde <myfirstname@osa.pri.ee> - 2019-09-30 22:26 +0300
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 19:46 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:32 +0200
Re: alloca()-support Paavo Helde <myfirstname@osa.pri.ee> - 2019-10-01 09:08 +0300
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 08:35 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 18:48 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 18:51 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 18:55 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 18:58 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 19:53 +0200
Re: alloca()-support Keith Thompson <kst-u@mib.org> - 2019-09-30 11:13 -0700
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 19:38 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:41 +0200
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-01 15:19 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 17:31 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-01 18:58 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 21:24 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:28 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:30 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:36 +0000
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:01 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-02 04:42 +0000
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:10 +0200
Re: alloca()-support Mel <mel@zzzzz.com> - 2019-10-02 15:13 +0200
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-01 21:10 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 21:25 +0200
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-01 20:44 +0000
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-01 23:26 +0200
Re: alloca()-support Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-10-01 21:08 -0600
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:19 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 06:39 +0200
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-02 10:34 +0200
Re: alloca()-support Mel <mel@zzzzz.com> - 2019-10-02 15:14 +0200
Re: alloca()-support Mel <mel@zzzzz.com> - 2019-10-02 15:18 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-02 15:21 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-03 04:09 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-03 07:48 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-03 05:49 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-03 07:52 +0200
Re: alloca()-support Melzzzzz <Melzzzzz@zzzzz.com> - 2019-10-03 06:46 +0000
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-03 10:59 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-10-03 13:39 +0200
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-03 13:23 +0000
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-03 15:38 +0200
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-10-03 14:51 +0000
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-04 09:49 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-10-03 21:47 +0200
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-04 09:53 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-10-03 21:52 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:39 +0200
Re: alloca()-support James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-09-30 21:36 -0400
Re: alloca()-support Philipp Klaus Krause <pkk@spth.de> - 2019-09-30 19:14 +0200
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 19:16 +0200
Re: alloca()-support Robert Wessel <robertwessel2@yahoo.com> - 2019-10-01 00:18 -0500
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 07:43 +0200
Re: alloca()-support Keith Thompson <kst-u@mib.org> - 2019-10-01 02:42 -0700
Re: alloca()-support James Kuyper <jameskuyper@alumni.caltech.edu> - 2019-10-01 08:11 -0400
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-10-01 14:53 +0200
Re: alloca()-support scott@slp53.sl.home (Scott Lurndal) - 2019-09-30 17:52 +0000
Re: alloca()-support Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-09-30 11:20 -0600
Re: alloca()-support Bonita Montero <Bonita.Montero@gmail.com> - 2019-09-30 19:42 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 20:02 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 19:54 +0200
Re: alloca()-support Joe Pfeiffer <pfeiffer@cs.nmsu.edu> - 2019-09-30 14:28 -0600
Re: alloca()-support David Brown <david.brown@hesbynett.no> - 2019-10-01 09:38 +0200
Re: alloca()-support Soviet_Mario <SovietMario@CCCP.MIR> - 2019-09-30 20:01 +0200
Re: alloca()-support Manfred <noname@add.invalid> - 2019-10-01 17:45 +0200
Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 00:03 -0700
Re: alloca()-support Paavo Helde <myfirstname@osa.pri.ee> - 2019-10-02 11:30 +0300
Re: alloca()-support Ian Collins <ian-news@hotmail.com> - 2019-10-02 21:34 +1300
Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 01:36 -0700
Re: alloca()-support Ian Collins <ian-news@hotmail.com> - 2019-10-02 21:41 +1300
Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 02:28 -0700
Re: alloca()-support "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-10-02 02:35 -0700
Re: alloca()-support Frederick Gotham <cauldwell.thomas@gmail.com> - 2019-10-02 02:43 -0700
Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-02 16:26 +0300
Re: alloca()-support "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-10-02 12:33 -0700
Re: alloca()-support Anton Shepelev <anton.txt@gmail.com> - 2019-10-03 01:47 +0300
Re: alloca()-support "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2019-10-05 14:08 -0700
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