[Bug c++/59614] New: [4.9 regression] Explostion in compile time of heavily templated code

[Bug c++/59614] New: [4.9 regression] Explostion in compile time of heavily templated code

[ivanov.maxim at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59614

            Bug ID: 59614
           Summary: [4.9 regression] Explostion in compile time of heavily
                    templated code
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ivanov.maxim at gmail dot com

4.9 takes forever to compile code, which compiles in 9 seconds by version
4.8.2.

gdb shows that g++ spends time in "mark_type_abi_tags" function, which was
introduced in
http://gcc.gnu.org/git/?p=gcc.git;a=commit;h=9181c3d9ceed054efd8488eaea91d89353bb8d21

If I read patch correctly, 4.9 visits all template arguments recursively for
every template instantiation, but 4.8 didn't, at least not in "check_abi_tags".

I created following somewhat pathological, but still correct test case, with
help of Boost.MPL and Boost.Fusion, to make very deep template with high number
of occurrences of same templates in different parts of that template tree, you
can find it in this ticket attachment (had to compress it, otherwise it
wouldn't fit into bugzilla's 1000K size limit).

Version I was testing on is:

GNU C++ (SUSE Linux) version 4.9.0 20131210 [trunk revision 205857]
(x86_64-suse-linux)
    compiled by GNU C version 4.9.0 20131210 [trunk revision 205857], GMP
version 5.1.2, MPFR version 3.1.2, MPC version 1.0

Thank you for your time.

[Bug c++/59614] [4.9 regression] Explostion in compile time of heavily templated code

[ivanov.maxim at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59614

--- Comment #1 from Maxim Ivanov <ivanov.maxim at gmail dot com> ---
Created attachment 31526
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=31526&action=edit
example of templated code which takes forever to compile by 4.9

[Bug c++/59614] [4.9 regression] Explostion in compile time of heavily templated code

[ivanov.maxim at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59614

--- Comment #2 from Maxim Ivanov <ivanov.maxim at gmail dot com> ---
Oh, g++ cmdline arguments are just "-std=c++11 -save-temps"

[Bug c++/59614] [4.9 regression] Explostion in compile time of heavily templated code

[steven at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59614

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |compile-time-hog
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2013-12-28
                 CC|                            |jason at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #3 from Steven Bosscher <steven at gcc dot gnu.org> ---
Classic case of quadratic behavior. 
Why do even experienced developers continue to add this kind of
obvious bottle-necks?!

[Bug c++/59614] [4.9 regression] Explostion in compile time of heavily templated code

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59614

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.9.0

[Bug c++/59614] [4.9 regression] Explostion in compile time of heavily templated code

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59614

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org

[Bug c++/59614] [4.9 regression] Explostion in compile time of heavily templated code

[jason at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59614

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed.