[Bug c++/60976] New: Compilation with G++ 4.9.0 is 2-3 times slower than with 4.8.2

[astellar at ro dot ru]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=60976

            Bug ID: 60976
           Summary: Compilation with G++ 4.9.0 is 2-3 times slower than
                    with 4.8.2
           Product: gcc
           Version: 4.9.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: astellar at ro dot ru

Created attachment 32686
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=32686&action=edit
g++ -v output for 4.8.2

Hello. After test upgrade from 4.8.2 to 4.9.0 I've noticed that compilation
takes significantly more time than before. g++ -v output for both compilers is
in attachments.

I've compiled the same file from internal project with following switches.
Debug build here, but it's the same problem with release flags:
-std=gnu++11 -fvisibility=hidden -Wall -Wextra -Winit-self -Winvalid-pch
-Wfatal-errors -Woverloaded-virtual -fvisibility-inlines-hidden -O0 -g -pipe
-fsanitize=address -ftime-report

Full ftime-report output for both compilers is in attachments. From what I see,
these steps take significantly more time than before:
- phase lang. deferred   : 1.22 usr for 4.8.2, 4.08 usr for 4.9.0;
- template instantiation : 1.44 usr for 4.8.2, 5.59 usr for 4.9.0.

Some other numbers are higher too, but these 2 have the largest increase. I'm
not sure how to create a reduced test case from this project, but I will try
something on Monday.