[Bug c/69580] New: From 26 seconds to 10 minutes moving from gcc 5.3.1 to gcc 6.0.0

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69580

            Bug ID: 69580
           Summary: From 26 seconds to 10 minutes moving from gcc 5.3.1 to
                    gcc 6.0.0
           Product: gcc
           Version: 6.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: dcb314 at hotmail dot com
  Target Milestone: ---

Created attachment 37533
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=37533&action=edit
gzipped C source code

The attached C code seems to take about ten minutes on a 
recent version of gcc trunk.

$ (ulimit -t 1200; time ~/gcc/results.release/bin/gcc -c -O2 bug271.c) 

real    10m3.565s
user    9m56.967s
sys     0m0.846s

$ ~/gcc/results.release/bin/gcc -v
Using built-in specs.
COLLECT_GCC=/home/dcb/gcc/results.release/bin/gcc
COLLECT_LTO_WRAPPER=/home/dcb/gcc/results.release/libexec/gcc/x86_64-pc-linux-gnu/6.0.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../src/trunk/configure --prefix=/home/dcb/gcc/results.release
--disable-bootstrap --disable-multilib --disable-werror
--enable-checking=release --enable-languages=c,c++,fortran
Thread model: posix
gcc version 6.0.0 20160130 (experimental) (GCC) 

Compared to much less time on 5.3.1

$ (ulimit -t 1200; time gcc -c -O2 bug271.c) 
real    0m27.110s
user    0m26.533s
sys     0m0.372s
$ gcc -v
Using built-in specs.
COLLECT_GCC=/usr/bin/gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/5.3.1/lto-wrapper
Target: x86_64-redhat-linux
Configured with: ../configure --enable-bootstrap
--enable-languages=c,c++,objc,obj-c++,fortran,ada,go,lto --prefix=/usr
--mandir=/usr/share/man --infodir=/usr/share/info
--with-bugurl=http://bugzilla.redhat.com/bugzilla --enable-shared
--enable-threads=posix --enable-checking=release --enable-multilib
--with-system-zlib --enable-__cxa_atexit --disable-libunwind-exceptions
--enable-gnu-unique-object --enable-linker-build-id
--with-linker-hash-style=gnu --enable-plugin --enable-initfini-array
--disable-libgcj --with-isl --enable-libmpx --enable-gnu-indirect-function
--with-tune=generic --with-arch_32=i686 --build=x86_64-redhat-linux
Thread model: posix
gcc version 5.3.1 20151207 (Red Hat 5.3.1-2) (GCC) 
$