[Bug c++/53186] New: [C++11] missing devirtualization for operators "final"

[Bug c++/53186] New: [C++11] missing devirtualization for operators "final"

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

             Bug #: 53186
           Summary: [C++11] missing devirtualization for operators "final"
    Classification: Unclassified
           Product: gcc
           Version: 4.8.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P3
         Component: c++
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: vincenzo.innocente@cern.ch


the example below shows how the keyword "final" has NO effect in devirtualizing
operators while it works for methods (as solved in PR49488)

cat  opFinal.cpp
struct A {
  virtual void operator()();
  virtual void m();
};

struct F1 {
  virtual void operator()() final;
  virtual void m() final;
};

struct F2 final {
  virtual void operator()();
  virtual void m();
};


void fooAop(A & a) {a();}
void fooA(A & a) {a.m();}
void fooF1op(F1 & a) {a();}
void fooF1(F1 & a) {a.m();}
void fooF2op(F2 & a) {a();}
void fooF2(F2 & a) {a.m();}
c++ -std=gnu++11 -c opFinal.cpp; nm opFinal.o; otool -t -v -V -X opFinal.o |
c++filt
00000000000000c0 s EH_frame1
0000000000000021 T __Z4fooAR1A
0000000000000067 T __Z5fooF1R2F1
00000000000000a2 T __Z5fooF2R2F2
0000000000000000 T __Z6fooAopR1A
0000000000000046 T __Z7fooF1opR2F1
0000000000000081 T __Z7fooF2opR2F2
                 U __ZN2F11mEv
                 U __ZN2F21mEv
fooAop(A&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooA(A&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
addq    $0x08,%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooF1op(F1&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooF1(F1&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F1::m()
leave
ret
fooF2op(F2&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooF2(F2&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F2::m()
leave
ret
host-001:bugs48 innocent$ cat  opFinal.cpp
struct A {
  virtual void operator()();
  virtual void m();
};

struct F1 {
  virtual void operator()() final;
  virtual void m() final;
};

struct F2 final {
  virtual void operator()();
  virtual void m();
};


void fooAop(A & a) {a();}
void fooA(A & a) {a.m();}
void fooF1op(F1 & a) {a();}
void fooF1(F1 & a) {a.m();}
void fooF2op(F2 & a) {a();}
void fooF2(F2 & a) {a.m();}



host-001:bugs48 innocent$ c++ -std=gnu++11 -c opFinal.cpp; nm opFinal.o; otool
-t -v -V -X opFinal.o | c++filt
00000000000000c0 s EH_frame1
0000000000000021 T __Z4fooAR1A
0000000000000067 T __Z5fooF1R2F1
00000000000000a2 T __Z5fooF2R2F2
0000000000000000 T __Z6fooAopR1A
0000000000000046 T __Z7fooF1opR2F1
0000000000000081 T __Z7fooF2opR2F2
                 U __ZN2F11mEv
                 U __ZN2F21mEv
fooAop(A&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooA(A&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
addq    $0x08,%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooF1op(F1&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooF1(F1&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F1::m()
leave
ret
fooF2op(F2&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooF2(F2&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F2::m()
leave
ret
host-001:bugs48 innocent$ c++ -v
Using built-in specs.
COLLECT_GCC=c++
COLLECT_LTO_WRAPPER=/usr/local/libexec/gcc/x86_64-apple-darwin11.3.0/4.8.0/lto-wrapper
Target: x86_64-apple-darwin11.3.0
Configured with: ./configure --enable-languages=c,c++,fortran
--disable-multilib --disable-bootstrap --enable-lto -disable-libitm :
(reconfigured) ./configure --enable-languages=c,c++,fortran --disable-multilib
--disable-bootstrap --enable-lto -disable-libitm
Thread model: posix
gcc version 4.8.0 20120416 (experimental) [trunk revision 186494] (GCC)

[Bug c++/53186] [C++11] missing devirtualization for operators "final"

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2012-05-03
         AssignedTo|unassigned at gcc dot       |paolo.carlini at oracle dot
                   |gnu.org                     |com
   Target Milestone|---                         |4.8.0
     Ever Confirmed|0                           |1

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-03 00:50:41 UTC ---
Confirmed.

It looks like we do not devirtualize all sorts of operators (conversions,
arithmetic, logic...) but the recipe is essentially the same.

I'm going to attach a draft patch which you may want to start testing (passes
the testsuite).

[Bug c++/53186] [C++11] missing devirtualization for operators "final"

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

--- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-03 00:51:22 UTC ---
Created attachment 27295
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27295
Draft

[Bug c++/53186] [C++11] missing devirtualization for operators "final"

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

--- Comment #3 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2012-05-03 06:42:46 UTC ---
not bad…

hope it could be back ported to 4.7.1


c++ -std=gnu++11 -c opFinal.cpp; nm opFinal.o; otool -t -v -V -X opFinal.o |
c++filt
00000000000000b0 s EH_frame1
0000000000000021 T __Z4fooAR1A
0000000000000060 T __Z5fooF1R2F1
0000000000000094 T __Z5fooF2R2F2
0000000000000000 T __Z6fooAopR1A
0000000000000046 T __Z7fooF1opR2F1
000000000000007a T __Z7fooF2opR2F2
                 U __ZN2F11mEv
                 U __ZN2F1clEv
                 U __ZN2F21mEv
                 U __ZN2F2clEv
fooAop(A&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooA(A&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    (%rax),%rax
addq    $0x08,%rax
movq    (%rax),%rax
movq    0xf8(%rbp),%rdx
movq    %rdx,%rdi
call    *%rax
leave
ret
fooF1op(F1&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F1::operator()()
leave
ret
fooF1(F1&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F1::m()
leave
ret
fooF2op(F2&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F2::operator()()
leave
ret
fooF2(F2&):
pushq    %rbp
movq    %rsp,%rbp
subq    $0x10,%rsp
movq    %rdi,0xf8(%rbp)
movq    0xf8(%rbp),%rax
movq    %rax,%rdi
callq    F2::m()
leave
ret

[Bug c++/53186] [C++11] missing devirtualization for operators "final"

[vincenzo.innocente at cern dot ch]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

--- Comment #4 from vincenzo Innocente <vincenzo.innocente at cern dot ch> 2012-05-03 06:46:01 UTC ---
   Ciao Paolo,
grazie per il patch.

Io no so quale sia lo "standard" gcc, ma credo sarebbe meglio distribuire patch
che si applicano direttamente dalla directory principale e non da una
subdirectory specifica.
Il tuo in particolare richiede 
cd gcc/cp
patch -p) < …
cd ../../
make

v.


On 3 May, 2012, at 2:51 AM, paolo.carlini at oracle dot com wrote:

> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186
> 
> --- Comment #2 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-03 00:51:22 UTC ---
> Created attachment 27295
>  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=27295
> Draft
> 
> --

[Bug c++/53186] [C++11] missing devirtualization for operators "final"

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

--- Comment #5 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-05-03 14:28:52 UTC ---
Author: paolo
Date: Thu May  3 14:28:46 2012
New Revision: 187097

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187097
Log:
/cp
2012-05-03  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/53186
    * call.c (build_over_call): Handle final member functions
    and class types.
    (build_new_method_call_1): Do not handle here.

/testsuite
2012-05-03  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/53186
    * g++.dg/other/final2.C: New.

Added:
    trunk/gcc/testsuite/g++.dg/other/final2.C
Modified:
    trunk/gcc/cp/ChangeLog
    trunk/gcc/cp/call.c
    trunk/gcc/testsuite/ChangeLog

[Bug c++/53186] [C++11] missing devirtualization for operators "final"

[paolo at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

--- Comment #6 from paolo at gcc dot gnu.org <paolo at gcc dot gnu.org> 2012-05-03 14:32:20 UTC ---
Author: paolo
Date: Thu May  3 14:32:15 2012
New Revision: 187098

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=187098
Log:
/cp
2012-05-03  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/53186
    * call.c (build_over_call): Handle final member functions
    and class types.
    (build_new_method_call_1): Do not handle here.

/testsuite
2012-05-03  Paolo Carlini  <paolo.carlini@oracle.com>

    PR c++/53186
    * g++.dg/other/final2.C: New.

Added:
    branches/gcc-4_7-branch/gcc/testsuite/g++.dg/other/final2.C
Modified:
    branches/gcc-4_7-branch/gcc/cp/ChangeLog
    branches/gcc-4_7-branch/gcc/cp/call.c
    branches/gcc-4_7-branch/gcc/testsuite/ChangeLog

[Bug c++/53186] [C++11] missing devirtualization for operators "final"

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53186

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|4.8.0                       |4.7.1

--- Comment #7 from Paolo Carlini <paolo.carlini at oracle dot com> 2012-05-03 14:33:09 UTC ---
Done for mainline and 4.7.1.