[Bug regression/58244] New: global variable: many THOUSANDS times slower execution

["martin.konopka at stuba dot sk" <gcc-bugzilla at gcc dot gnu dot org>]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=58244

            Bug ID: 58244
           Summary: global variable: many THOUSANDS times slower execution
           Product: gcc
           Version: 4.7.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
          Assignee: unassigned at gcc dot gnu.org
          Reporter: martin.konopka at stuba dot sk

Created attachment 30701
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=30701&action=edit
sample C code to demonstrate the performance issue

* I have a very small sample code written in pure C.
* I am using 64-bit linux:
 - Linux Mint Maya with gcc 4.6.3
   (gcc and libraries same as ubuntu 12.04 LTS)
 - ubuntu 12.10  with gcc 4.7.2
 - newest Scientific Linux with compilers 4.4.7  and  4.7.3

When I declare a simple variable (auxvar , see the code) as a local one, then
the executable is about as fast as it should be.

When I declare the variable as a global one, then the executable becomes
insanely slow.

The behaviour is the same for any of the above mentioned linuxes and compiler
versions. Please see attached C code. Compile it using

gcc -O2 -Wall slowcode.c -lm

Please do NOT declare auxvar both globally and locally. Use either local or
global declaration.

Thanks.