[Bug c++/58999] sizeof ...(T) is very slow than clang

[Bug c++/58999] sizeof ...(T) is very slow than clang

[khurshid.normuradov at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58999

khurshid <khurshid.normuradov at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |http://stackoverflow.com/qu
                   |                            |estions/19783205/why-sizeof
                   |                            |-t-so-slow-implement-c14-ma
                   |                            |ke-index-sequence-without-s
                   |                            |izeof?noredirect=1#comment2
                   |                            |9408465_19783205

--- Comment #1 from khurshid <khurshid.normuradov at gmail dot com> ---
http://stackoverflow.com/questions/19783205/why-sizeof-t-so-slow-implement-c14-make-index-sequence-without-sizeof

[Bug c++/58999] sizeof ...(T) is very slow than clang

[vhaisman at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58999

--- Comment #2 from Václav Zeman <vhaisman at gmail dot com> ---
You should probably add the complete test case as an attachment.
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Subject: [Bug c++/59001] Use of -pedantic throws errors instead of warnings
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idY001

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
      Known to work|                            |4.7.3, 4.8.2, 4.9.0
         Resolution|---                         |WORKSFORME

--- Comment #1 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Fixed looooong time ago, circa 4.4.

[Bug c++/58999] sizeof ...(T) is very slow than clang

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58999

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-11-05
     Ever confirmed|0                           |1

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Václav Zeman from comment #2)
> You should probably add the complete test case as an attachment.

There's no need, the testcase is small and self-contained and already present.

However, khurshid, you haven't said what version of GCC you are using or how it
was configured.
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Subject: [Bug c++/58993] failure to access pointer to protected member method in base from derived class specialization
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idX993

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Chris Studholme from comment #0)
> Sample code:
>
> class base {
> protected:
>     typedef void (base::*foo_type)() const;
>     void foo() const {}
> };
>
> template <typename T>
> struct bar : public base {
>     foo_type test() {
>         return &base::foo;       // OK

The bug is here, this should be an error too (but G++ has lots of bugs with
access checking in templates)

The name foo is a protected member of base, to access it you have to do it via
the derived class, i.e. you should do:

        return &bar::foo;

[Bug c++/58999] sizeof ...(T) is very slow than clang

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58999

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
--enable-checking=release makes quite a big difference

$ time ~/gcc/4.x/bin/g++  -std=c++11 -c t.cc -ftime-report

Execution times (seconds)
 phase setup             :   0.00 ( 0%) usr   0.01 ( 2%) sys   0.05 ( 0%) wall 
  1323 kB ( 0%) ggc
 phase parsing           :  12.84 (100%) usr   0.44 (96%) sys  13.31 (99%) wall
1422475 kB (100%) ggc
 phase opt and generate  :   0.00 ( 0%) usr   0.01 ( 2%) sys   0.09 ( 1%) wall 
    42 kB ( 0%) ggc
 phase last asm          :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 |overload resolution    :   0.03 ( 0%) usr   0.01 ( 2%) sys   0.03 ( 0%) wall 
  1153 kB ( 0%) ggc
 garbage collection      :   0.19 ( 1%) usr   0.00 ( 0%) sys   0.19 ( 1%) wall 
     0 kB ( 0%) ggc
 parser function body    :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     1 kB ( 0%) ggc
 template instantiation  :  12.65 (99%) usr   0.44 (96%) sys  13.11 (97%) wall
1422149 kB (100%) ggc
 tree gimplify           :   0.00 ( 0%) usr   0.01 ( 2%) sys   0.00 ( 0%) wall 
     0 kB ( 0%) ggc
 tree STMT verifier      :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 expand                  :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall 
     1 kB ( 0%) ggc
 LRA non-specific        :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 shorten branches        :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall 
     0 kB ( 0%) ggc
 symout                  :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 rest of compilation     :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.03 ( 0%) wall 
     2 kB ( 0%) ggc
 TOTAL                 :  12.84             0.46            13.50           
1423858 kB
Extra diagnostic checks enabled; compiler may run slowly.
Configure with --enable-checking=release to disable checks.

real    0m14.014s
user    0m12.853s
sys     0m0.528s

$ time ~/gcc/4.x-release/bin/g++  -std=c++11 -c t.cc -ftime-report

Execution times (seconds)
 phase setup             :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.05 ( 1%) wall 
  1374 kB ( 0%) ggc
 phase parsing           :   7.40 (100%) usr   0.28 (100%) sys   7.71 (98%)
wall 1422475 kB (100%) ggc
 phase opt and generate  :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.05 ( 1%) wall 
    42 kB ( 0%) ggc
 phase last asm          :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 |overload resolution    :   0.06 ( 1%) usr   0.01 ( 4%) sys   0.07 ( 1%) wall 
  1153 kB ( 0%) ggc
 garbage collection      :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 parser (global)         :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall 
   309 kB ( 0%) ggc
 template instantiation  :   7.39 (100%) usr   0.28 (100%) sys   7.68 (98%)
wall 1422149 kB (100%) ggc
 expand                  :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     1 kB ( 0%) ggc
 integrated RA           :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
    24 kB ( 0%) ggc
 shorten branches        :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 symout                  :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall 
     0 kB ( 0%) ggc
 rest of compilation     :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall 
     2 kB ( 0%) ggc
 TOTAL                 :   7.41             0.28             7.83           
1423909 kB

real    0m8.237s
user    0m7.420s
sys     0m0.328s

But it's still orders of magnitude slower than clang

[Bug c++/58999] sizeof ...(T) is very slow than clang

[paolo.carlini at oracle dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58999

--- Comment #5 from Paolo Carlini <paolo.carlini at oracle dot com> ---
Probably a meta-bug about this sort of issue would also make sense. We have got
a few bugs already.