[Bug c++/33661] template methods forget explicit local reg vars

[Bug c++/33661] template methods forget explicit local reg vars

[s.schuh85 at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

Stefan Schuh <s.schuh85 at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |s.schuh85 at gmail dot com

--- Comment #9 from Stefan Schuh <s.schuh85 at gmail dot com> 2011-08-24 10:00:48 UTC ---
I can confirm this bug in gcc version 4.5.2 on i686-linux-gnu 
and in gcc version 4.6.0 on s390x-ibm-linux-gnu

[Bug c++/33661] template methods forget explicit local reg vars

[Aleksandrs.Saveljevs at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

--- Comment #10 from Aleksandrs Saveljevs <Aleksandrs.Saveljevs at gmail dot com> 2012-05-31 08:16:41 UTC ---
Confirming that the bug still exists on ARM, x86 and x86_64 as of GCC 4.6.3.

[Bug c++/33661] template methods forget explicit local reg vars

[adam at os dot inf.tu-dresden.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

--- Comment #11 from Adam Lackorzynski <adam at os dot inf.tu-dresden.de> ---
Confirming issue still exists for 4.7.4, 4.8.4, 4.9.2 and 5.0 (tested on
x86_64).

[Bug c++/33661] template methods forget explicit local reg vars

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |krebbel at gcc dot gnu.org

--- Comment #12 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
*** Bug 66393 has been marked as a duplicate of this bug. ***

[Bug c++/33661] template methods forget explicit local register asm vars

[mp8191mp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

Martin Papik <mp8191mp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mp8191mp at gmail dot com

--- Comment #17 from Martin Papik <mp8191mp at gmail dot com> ---

Hello, I found a bug, which I think is a duplicate of this one, but am not 100%
sure.

Below is a minimal piece of code which triggers the bug. All versions of gcc
seem to be affected, as seen on compiler explorer,
https://godbolt.org/z/jFMj8b, which also shows a difference in gimple, the
templated version is missing the explicit naming attributes.

Is this the same bug? If so, is there some technical reason why a clear
miscompilation persists for as long as it seems to? What I mean is this, if a
bug like this persists for this long, it could be taken to mean that the bug is
too big for a casual volunteer. Would that be the case? Can someone familiar
with the code base tell me what I'd need to know to fix this, e.g. what's wrong
with the patch, is it better to fix the patch or start from scratch.


$ cat bug.cpp
#define DEMONSTRABLY_IDENTICAL                                  \
        long ret;                                               \
        register long r10 __asm__("r10") = (long)a4;            \
        __asm__ __volatile__ ("syscall"                         \
                : "=a"(ret)                                     \
                : "a"(n), "D"(a1), "S"(a2), "d"(a3), "r"(r10)   \
                : "rcx", "r11", "memory"                        \
                );
enum class sysnr : long {
        // accept4 has enough parameters to require extra registers and trigger
the bug
        accept4 = 0x120
};
static __inline long sys_01(long n, long a1, long a2, long a3, long a4)
{
        DEMONSTRABLY_IDENTICAL
        return ret;
}
template <sysnr SYS_NR, typename RET, typename T1, typename T2, typename T3,
typename T4>
RET sys_02(T1 a1, T2 a2, T3 a3, T4 a4) {
        constexpr long n = (long) SYS_NR;
        DEMONSTRABLY_IDENTICAL
        return (RET)ret;
}
void test_01 () {
        sys_01( (long)sysnr::accept4, 0xfeed01, 0xfeed02, 0xfeed03, 0xfeed04 );
}
void test_02() {
        sys_02<sysnr::accept4, long>( 0xfeed01, 0xfeed02, 0xfeed03, 0xfeed04 );
}
void test_03() {
        sys_02<sysnr::accept4, long, long, long, long, long>( 0xfeed01,
0xfeed02, 0xfeed03, 0xfeed04 );
}

$ g++ -std=c++11 -O1 bug.cpp -c -o bug.c
$ objdump -Cd bug.o 

bug.o:     file format elf64-x86-64


Disassembly of section .text:

0000000000000000 <test_01()>:
   0:   41 ba 04 ed fe 00       mov    $0xfeed04,%r10d
   6:   b8 20 01 00 00          mov    $0x120,%eax
   b:   bf 01 ed fe 00          mov    $0xfeed01,%edi
  10:   be 02 ed fe 00          mov    $0xfeed02,%esi
  15:   ba 03 ed fe 00          mov    $0xfeed03,%edx
  1a:   0f 05                   syscall 
  1c:   c3                      retq   

000000000000001d <test_02()>:
  1d:   b8 20 01 00 00          mov    $0x120,%eax
  22:   bf 01 ed fe 00          mov    $0xfeed01,%edi
  27:   be 02 ed fe 00          mov    $0xfeed02,%esi
  2c:   ba 03 ed fe 00          mov    $0xfeed03,%edx
  31:   41 b8 04 ed fe 00       mov    $0xfeed04,%r8d
  37:   0f 05                   syscall 
  39:   c3                      retq   

000000000000003a <test_03()>:
  3a:   b8 20 01 00 00          mov    $0x120,%eax
  3f:   bf 01 ed fe 00          mov    $0xfeed01,%edi
  44:   be 02 ed fe 00          mov    $0xfeed02,%esi
  49:   ba 03 ed fe 00          mov    $0xfeed03,%edx
  4e:   41 b8 04 ed fe 00       mov    $0xfeed04,%r8d
  54:   0f 05                   syscall 
  56:   c3                      retq

[Bug c++/33661] template methods forget explicit local register asm vars

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

--- Comment #18 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:6bb207b468da36d9d99c63409dc4098514759c90

commit r11-6958-g6bb207b468da36d9d99c63409dc4098514759c90
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jan 28 16:13:11 2021 +0100

    c++: Fix up handling of register ... asm ("...") vars in templates
[PR33661, PR98847]

    As the testcase shows, for vars appearing in templates, we don't attach
    the asm spec string to the pattern decls, nor pass it back to
cp_finish_decl
    during instantiation.

    The following patch does that.

    2021-01-28  Jakub Jelinek  <jakub@redhat.com>

            PR c++/33661
            PR c++/98847
            * decl.c (cp_finish_decl): For register vars with asmspec in
templates
            call set_user_assembler_name and set DECL_HARD_REGISTER.
            * pt.c (tsubst_expr): When instantiating DECL_HARD_REGISTER vars,
            pass asmspec_tree to cp_finish_decl.

            * g++.target/i386/pr98847.C: New test.

[Bug c++/33661] template methods forget explicit local register asm vars

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

--- Comment #19 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:cf93f94b3498f3925895fb0bbfd4b64232b9987a

commit r10-9323-gcf93f94b3498f3925895fb0bbfd4b64232b9987a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jan 28 16:13:11 2021 +0100

    c++: Fix up handling of register ... asm ("...") vars in templates
[PR33661, PR98847]

    As the testcase shows, for vars appearing in templates, we don't attach
    the asm spec string to the pattern decls, nor pass it back to
cp_finish_decl
    during instantiation.

    The following patch does that.

    2021-01-28  Jakub Jelinek  <jakub@redhat.com>

            PR c++/33661
            PR c++/98847
            * decl.c (cp_finish_decl): For register vars with asmspec in
templates
            call set_user_assembler_name and set DECL_HARD_REGISTER.
            * pt.c (tsubst_expr): When instantiating DECL_HARD_REGISTER vars,
            pass asmspec_tree to cp_finish_decl.

            * g++.target/i386/pr98847.C: New test.

[Bug c++/33661] template methods forget explicit local register asm vars

[fw at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

Florian Weimer <fw at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |nate at verse dot com

--- Comment #20 from Florian Weimer <fw at gcc dot gnu.org> ---
*** Bug 58118 has been marked as a duplicate of this bug. ***

[Bug c++/33661] template methods forget explicit local register asm vars

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

--- Comment #21 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:ef5db37cc4e80b229502bea7d6e2daa95ad6f805

commit r9-9412-gef5db37cc4e80b229502bea7d6e2daa95ad6f805
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jan 28 16:13:11 2021 +0100

    c++: Fix up handling of register ... asm ("...") vars in templates
[PR33661, PR98847]

    As the testcase shows, for vars appearing in templates, we don't attach
    the asm spec string to the pattern decls, nor pass it back to
cp_finish_decl
    during instantiation.

    The following patch does that.

    2021-01-28  Jakub Jelinek  <jakub@redhat.com>

            PR c++/33661
            PR c++/98847
            * decl.c (cp_finish_decl): For register vars with asmspec in
templates
            call set_user_assembler_name and set DECL_HARD_REGISTER.
            * pt.c (tsubst_expr): When instantiating DECL_HARD_REGISTER vars,
            pass asmspec_tree to cp_finish_decl.

            * g++.target/i386/pr98847.C: New test.

    (cherry picked from commit cf93f94b3498f3925895fb0bbfd4b64232b9987a)

[Bug c++/33661] template methods forget explicit local register asm vars

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

--- Comment #22 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-8 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:712ffc0ad150aadfa5b91f493075e88fd050189f

commit r8-10878-g712ffc0ad150aadfa5b91f493075e88fd050189f
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Thu Jan 28 16:13:11 2021 +0100

    c++: Fix up handling of register ... asm ("...") vars in templates
[PR33661, PR98847]

    As the testcase shows, for vars appearing in templates, we don't attach
    the asm spec string to the pattern decls, nor pass it back to
cp_finish_decl
    during instantiation.

    The following patch does that.

    2021-01-28  Jakub Jelinek  <jakub@redhat.com>

            PR c++/33661
            PR c++/98847
            * decl.c (cp_finish_decl): For register vars with asmspec in
templates
            call set_user_assembler_name and set DECL_HARD_REGISTER.
            * pt.c (tsubst_expr): When instantiating DECL_HARD_REGISTER vars,
            pass asmspec_tree to cp_finish_decl.

            * g++.dg/opt/pr98847.C: New test.

    (cherry picked from commit cf93f94b3498f3925895fb0bbfd4b64232b9987a)

[Bug c++/33661] template methods forget explicit local register asm vars

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
                 CC|                            |jakub at gcc dot gnu.org
         Resolution|---                         |FIXED

--- Comment #23 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed.

[Bug c++/33661] template methods forget explicit local register asm vars

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |8.5

[Bug c++/33661] template methods forget explicit local reg vars

[adam at os dot inf dot tu-dresden dot de]

------- Comment #8 from adam at os dot inf dot tu-dresden dot de  2008-04-30 20:22 -------
(In reply to comment #7)
> This is not a regression, however it is a bug, it has to be fixed. Inline
> assembly coupled with templates is very powerful, however because of this bug
> it is unusable :-(

I fully agree. I don't know how hard this one is to fix so at least a
warning/error would be good to have. Silently ignoring the allocation just
causes bugs nobody wants to have.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

[Bug c++/33661] template methods forget explicit local reg vars

[vincent dot riviere at freesbee dot fr]

------- Comment #7 from vincent dot riviere at freesbee dot fr  2008-04-30 15:32 -------
This is not a regression, however it is a bug, it has to be fixed. Inline
assembly coupled with templates is very powerful, however because of this bug
it is unusable :-(
If I remember well, a workaround is to put the assembly in an inline global
function, then call it from the template method.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

[Bug c++/33661] template methods forget explicit local reg vars

[adam at os dot inf dot tu-dresden dot de]

------- Comment #6 from adam at os dot inf dot tu-dresden dot de  2008-04-30 13:34 -------
Even if this is not a regression it would be very helpful if g++ would emit a
warning that the register allocation will be ignored. Those bugs are subtle.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

[Bug c++/33661] template methods forget explicit local reg vars

[pinskia at gcc dot gnu dot org]

------- Comment #5 from pinskia at gcc dot gnu dot org  2008-04-29 17:09 -------
*** Bug 36080 has been marked as a duplicate of this bug. ***


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |adam at os dot inf dot tu-
                   |                            |dresden dot de


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

[Bug c++/33661] template methods forget explicit local reg vars

[vincent dot riviere at freesbee dot fr]

------- Comment #4 from vincent dot riviere at freesbee dot fr  2008-02-05 19:56 -------
Same problem with GCC 4.3-20080201 on target i686-pc-linux-gnu


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

[Bug c++/33661] template methods forget explicit local reg vars

[rguenth at gcc dot gnu dot org]

------- Comment #3 from rguenth at gcc dot gnu dot org  2008-02-05 10:28 -------
This works for me on x86_64 with 4.3.0.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

[Bug c++/33661] template methods forget explicit local reg vars

[vincent dot riviere at freesbee dot fr]

------- Comment #2 from vincent dot riviere at freesbee dot fr  2008-02-02 20:48 -------
Still fails in GCC release 4.2.3


-- 

vincent dot riviere at freesbee dot fr changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|3.3.3 4.1.0 4.3.0           |3.3.3 4.1.0 4.2.3 4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661

[Bug c++/33661] template methods forget explicit local reg vars

[pinskia at gcc dot gnu dot org]

------- Comment #1 from pinskia at gcc dot gnu dot org  2007-12-10 01:55 -------
Confirmed,
It also fails with 3.3 so this is not a regression.
A testcase for PPC:
template<class T>
class Tpl
{
public:
        static long* MySysCall()
        {
                register long retval __asm__("r3");

                asm
                (
                        "trap   #0\n\t"
                        "move.l %0,%0\n\t"
                : "=r"(retval)
                :
                : "r4"
                );

                return (long*)retval;
        }
};

void f()
{
        long* p = Tpl<char>::MySysCall();
        *p = 1;
}

Note I did not change the inline-asm's string though so it will not assemble.




-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
           Keywords|                            |wrong-code
      Known to fail|                            |3.3.3 4.1.0 4.3.0
   Last reconfirmed|0000-00-00 00:00:00         |2007-12-10 01:55:24
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33661