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Groups > comp.lang.c++ > #80190
| From | MrSpook_zn7@4tzq7j92.gov |
|---|---|
| Newsgroups | comp.lang.c++ |
| Subject | Re: Is this really necessary |
| Date | 2021-06-06 13:59 +0000 |
| Organization | Aioe.org NNTP Server |
| Message-ID | <s9ikcf$1j50$1@gioia.aioe.org> (permalink) |
| References | <s9fl3f$ha7$1@dont-email.me> <s9fq58$3qr$1@dont-email.me> <s9g72u$de0$1@gioia.aioe.org> <ii1rr0F9q7oU1@mid.individual.net> |
On Sat, 5 Jun 2021 19:50:23 +0200
Bo Persson <bo@bo-persson.se> wrote:
>On 2021-06-05 at 18:00, MrSpook_rs7x@4hhtozmpj299zx.tv wrote:
>> #include <stdio.h>
>> #include <stdint.h>
>> #include <stdlib.h>
>>
>> int main()
>> {
>> uint32_t i;
>> uint32_t j;
>> uint32_t *p1;
>> uint32_t *p2;
>>
>> p1 = (&j < &i ? &j : &i);
>> p2 = (uint32_t *)((char *)p1 + 1);
>> printf("p1 = %p, p2 = %p\n",p1,p2);
>> *p2 = (uint32_t)-1;
>> printf("*p2 = %u\n",*p2);
>>
>> p1 = (uint32_t *)malloc(sizeof(uint32_t) * 2);
>> p2 = (uint32_t *)((char *)p1 + 1);
>> printf("p1 = %p, p2 = %p\n",p1,p2);
>> *p2 = (uint32_t)-1;
>> printf("*p2 = %u\n",*p2);
>> return 0;
>> }
>>
>
>You did notice (right?) that the optimiser transformed
>
>printf("*p2 = %u\n",*p2);
>
>into
>
>printf("*p2 = %u\n", (uint32_t)-1);
>
>resulting in the code
>
>00007FF71990106D mov rcx,rsi
>00007FF719901070 mov edx,0FFFFFFFFh
>00007FF719901075 call printf (07FF719901090h)
Nope, guess the compiler didn't notice either:
movq -40(%rbp), %rax ## 8-byte Reload
movq %rax, -24(%rbp)
movq -24(%rbp), %rax
addq $1, %rax
movq %rax, -32(%rbp)
movq -24(%rbp), %rsi
movq -32(%rbp), %rdx
leaq L_.str(%rip), %rdi
movb $0, %al
callq _printf
movq -32(%rbp), %rcx
movl $-1, (%rcx)
movq -32(%rbp), %rcx
movl (%rcx), %esi
leaq L_.str.1(%rip), %rdi
movl %eax, -44(%rbp) ## 4-byte Spill
movb $0, %al
callq _printf
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Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 12:53 +0200
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 14:19 +0200
Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 14:27 +0200
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 14:33 +0200
Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 15:06 +0200
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 15:29 +0200
Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-05 17:38 +0200
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 17:51 +0200
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-05 11:56 -0400
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-06-05 19:08 -0400
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-06 11:24 +0200
Re: Is this really necessary Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-06-06 10:33 +0100
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 07:56 -0400
Re: Is this really necessary Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-06-06 15:00 +0100
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 16:20 -0700
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 00:44 -0700
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-07 12:13 -0700
Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-06-07 21:58 +0200
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 10:25 -0700
Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-08-07 21:21 +0200
Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-05 06:34 -0700
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-05 20:03 -0400
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 12:59 -0700
Re: Is this really necessary MrSpud_85yGi2@1ahbfz.gov - 2021-08-08 09:18 +0000
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-08 09:23 -0400
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-08 15:04 +0000
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-08 13:14 -0400
Re: Is this really necessary MrSpud_1dgrmf@dx58865qyrdw30lqllb.info - 2021-08-09 08:21 +0000
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-09 08:53 +0000
Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-08-09 19:53 +0200
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 05:22 +0000
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 14:54 +0000
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-10 11:41 -0700
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-11 05:39 +0000
Re: Is this really necessary Chris Vine <chris@cvine--nospam--.freeserve.co.uk> - 2021-08-08 20:01 +0100
Re: Is this really necessary MrSpud_ifhov@nldls6_1kg3nl2qnwv.biz - 2021-08-09 08:19 +0000
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-09 08:55 +0000
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-09 12:16 -0400
Re: Is this really necessary MrSpud_HG@_0b772d8ha3yjo0xb.edu - 2021-08-09 16:23 +0000
Re: Is this really necessary Vir Campestris <vir.campestris@invalid.invalid> - 2021-08-09 21:50 +0100
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-09 20:57 -0400
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 01:12 +0000
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-09 21:21 -0400
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-10 07:13 -0700
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 05:29 +0000
Re: Is this really necessary MrSpud_12tus_Atff@bya886olr5o8dhu9.ac.uk - 2021-08-10 07:28 +0000
Re: Is this really necessary Mike Terry <news.dead.person.stones@darjeeling.plus.com> - 2021-08-10 15:34 +0100
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 14:59 +0000
Re: Is this really necessary MrSpud_wPgnov999o@vv7a6.tv - 2021-08-10 15:54 +0000
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-10 11:29 -0700
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 08:45 +0000
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-11 07:05 -0700
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 14:18 +0000
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 14:57 +0000
Re: Is this really necessary MrSpud_pb9bpp7Ej@6urvt16b9fax.gov.uk - 2021-08-10 07:23 +0000
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 15:02 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-10 06:11 -0700
Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-08-10 16:13 +0200
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-11 12:40 -0700
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-12 08:20 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-12 03:50 -0700
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-12 14:58 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-12 08:29 -0700
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-12 15:39 +0000
Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-08-12 20:07 +0300
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-13 07:16 +0000
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 09:26 +0000
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-13 10:30 -0400
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 14:58 +0000
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-14 08:07 +0000
Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-08-14 10:40 -0700
Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-08-14 10:38 -0700
Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-08-13 15:30 +0200
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-13 11:18 -0700
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 03:20 -0700
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-14 13:24 -0700
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-14 20:33 +0000
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-15 00:40 -0400
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-15 07:02 -0700
Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-08-15 21:19 +0200
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-08-15 15:42 -0400
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-21 12:38 -0700
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-14 08:13 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 02:58 -0700
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-13 14:32 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 02:28 -0700
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-14 03:00 -0700
Re: Is this really necessary Bart <bc@freeuk.com> - 2021-08-14 14:03 +0100
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-14 15:06 +0000
Re: Is this really necessary "Chris M. Thomasson" <chris.m.thomasson.1@gmail.com> - 2021-08-12 12:06 -0700
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 09:19 +0000
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-13 14:35 +0000
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-13 14:58 +0000
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-10 15:03 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-11 12:54 -0700
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-11 20:20 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-12 03:42 -0700
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-11 05:45 +0000
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-11 05:26 -0700
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-11 14:06 +0000
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-08-11 14:01 +0000
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-09 23:20 -0400
Re: Is this really necessary MrSpud_m7k7yilq_8@u6w.biz - 2021-08-10 07:26 +0000
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 07:51 +0000
Re: Is this really necessary MrSpud_ggBp1lq0@lxz.tv - 2021-08-10 07:59 +0000
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-10 12:24 +0000
Re: Is this really necessary MrSpud_u7lm@bxuc3wy1g3cxiqu5j2x1_7iu.com - 2021-08-10 15:51 +0000
Re: Is this really necessary Juha Nieminen <nospam@thanks.invalid> - 2021-08-11 05:47 +0000
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 08:46 +0000
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-08-10 11:20 +0200
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-10 10:27 -0400
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-08-10 17:44 +0200
Re: Is this really necessary MrSpud_885p_dugji@l6zhsgj_v6t3dbj.tv - 2021-08-10 15:50 +0000
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-08-11 08:31 +0200
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-08-10 10:27 -0400
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-08-10 11:27 -0700
Re: Is this really necessary mickspud@downthefarm.com - 2021-08-11 08:44 +0000
Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-08-11 16:05 +0300
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-10 06:41 -0700
Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-06-06 18:48 +0300
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 14:26 -0400
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 16:10 -0700
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 21:30 -0400
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 18:49 -0700
Re: Is this really necessary Keith Thompson <Keith.S.Thompson+u@gmail.com> - 2021-06-06 18:51 -0700
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-06 22:57 -0400
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 09:43 -0700
Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-07 09:51 -0700
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 10:22 -0700
Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-06-07 10:13 -0700
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 10:22 -0700
Re: Is this really necessary "james...@alumni.caltech.edu" <jameskuyper@alumni.caltech.edu> - 2021-08-07 12:40 -0700
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-08-07 12:54 -0700
Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-06 23:17 -0700
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 09:19 -0700
Re: Is this really necessary Paavo Helde <myfirstname@osa.pri.ee> - 2021-06-07 21:58 +0300
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-10 11:29 -0700
Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-05 05:38 -0700
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 15:41 +0200
Re: Is this really necessary Öö Tiib <ootiib@hot.ee> - 2021-06-05 08:18 -0700
Re: Is this really necessary Richard Damon <Richard@Damon-Family.org> - 2021-06-05 11:58 -0400
Re: Is this really necessary MrSpook_rs7x@4hhtozmpj299zx.tv - 2021-06-05 16:00 +0000
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-05 18:16 +0200
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-06 17:34 +0200
Re: Is this really necessary MrSpook_ie@q67rq6_2ly9ut44j.org - 2021-06-06 13:55 +0000
Re: Is this really necessary Bo Persson <bo@bo-persson.se> - 2021-06-05 19:50 +0200
Re: Is this really necessary MrSpook_zn7@4tzq7j92.gov - 2021-06-06 13:59 +0000
Re: Is this really necessary James Kuyper <jameskuyper@alumni.caltech.edu> - 2021-06-05 17:42 -0400
Re: Is this really necessary David Brown <david.brown@hesbynett.no> - 2021-06-06 11:05 +0200
Re: Is this really necessary Tim Rentsch <tr.17687@z991.linuxsc.com> - 2021-06-07 00:27 -0700
Re: Is this really necessary Vir Campestris <vir.campestris@invalid.invalid> - 2021-06-06 21:27 +0100
Re: Is this really necessary "Alf P. Steinbach" <alf.p.steinbach@gmail.com> - 2021-06-07 00:22 +0200
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-06-07 14:53 +0000
Re: Is this really necessary Bonita Montero <Bonita.Montero@gmail.com> - 2021-06-07 18:02 +0200
Re: Is this really necessary Vir Campestris <vir.campestris@invalid.invalid> - 2021-06-16 21:38 +0100
Re: Is this really necessary scott@slp53.sl.home (Scott Lurndal) - 2021-06-07 14:52 +0000
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