[Bug c++/18713] New: Large program size due to uninitialised global data (SCO)

[Bug c++/18713] New: Large program size due to uninitialised global data (SCO)

[bygoh at genting dot com dot my]

Configured with: ../sco/gcc-3.2.3/configure --prefix=/usr/local/gcc-3.2.3 --
enable-languages=c++ --with-gnu-as
Thread model: single
gcc version 3.2.3

System: SCO Unix 5.0.5

Compilation of source programs with declared but unitialised global data on the 
SCO system seems to cause the program to grow in proportion with the size of 
the data. Uninitialised data should be stored under BSS or the common section 
of a program. This seems to be the case for Linux but not on SCO.

-----
Test program: foo.cpp

struct My_t {
        char            myData[2048];
};
My_t myArr[10240];

int main ()
{
        return 0;
}

-----
Compilation: gcc -O -fconserve-space foo.cpp -lstdc++
Size listing (ls -l a.out) on SCO: 20977120
Size listing (ls -l a.out) on RedHat: 11341

However, converting the same program to a C standard and compiling with gcc on 
SCO produces the expected object code size as follows:

-----
Test program: foo.c

struct My_t {
        char            myData[2048];
};
struct My_t myArr[10240];

int
main ()
{
        return 0;
}

-----
Compilation: gcc foo.c
Size listing (ls -l a.out) on SCO: 5604

-- 
           Summary: Large program size due to uninitialised global data
                    (SCO)
           Product: gcc
           Version: 3.2.3
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: c++
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: bygoh at genting dot com dot my
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18713

[Bug target/18713] Large program size due to uninitialised global data (SCO)

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|c++                         |target
           Keywords|                            |missed-optimization


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18713

[Bug target/18713] Large program size due to uninitialised global data (SCO)

[bygoh at genting dot com dot my]

------- Additional Comments From bygoh at genting dot com dot my  2004-12-08 04:11 -------
Follow up on the earlier report, the size problem goes away when the global 
variables are declared as static:

struct My_t {
        char            myData[2048];
};
static My_t myArr[10240];

int main ()
{
        return 0;
}

Using nm on the object files that were generated:
without static keyword:
Symbols from foo.o:

[Index]   Value      Size    Type  Bind  Other Shndx   Name

[1]     |         0|       0|FILE |LOCL |0    |ABS    |foo.cpp
[2]     |         0|       0|SECT |LOCL |0    |2      |
[3]     |         0|       0|SECT |LOCL |0    |4      |
[4]     |         0|       0|SECT |LOCL |0    |5      |
[5]     |         0|       0|SECT |LOCL |0    |1      |
[6]     |         0|       0|SECT |LOCL |0    |6      |
[7]     |         0|20971520|OBJT |GLOB |0    |4      |myArr
[8]     |         0|      30|FUNC |GLOB |0    |2      |main

with static keyword:
Symbols from foo.o:

[Index]   Value      Size    Type  Bind  Other Shndx   Name

[1]     |         0|       0|FILE |LOCL |0    |ABS    |foo.cpp
[2]     |         0|       0|SECT |LOCL |0    |2      |
[3]     |         0|       0|SECT |LOCL |0    |4      |
[4]     |         0|       0|SECT |LOCL |0    |5      |
[5]     |         0|20971520|OBJT |LOCL |0    |5      |myArr
[6]     |         0|       0|SECT |LOCL |0    |1      |
[7]     |         0|       0|SECT |LOCL |0    |6      |
[8]     |         0|      30|FUNC |GLOB |0    |2      |main

The array was bound locally. Still doesn't solve the problem but its a work 
around for programs with a main line entry point.

NOTE: static is deprecated in a global context. Not that its going to go away 
or anything...

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18713

[Bug target/18713] Large program size due to uninitialised global data

[steven at gcc dot gnu dot org]

------- Additional Comments From steven at gcc dot gnu dot org  2004-12-08 08:56 -------
Bugs for gcc 3.2.3 are not going to be fixed.  Are you seeing this 
problem with more recent versions of GCC as well? 

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING
            Summary|Large program size due to   |Large program size due to
                   |uninitialised global data   |uninitialised global data
                   |(SCO)                       |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18713

[Bug target/18713] Large program size due to uninitialised global data

[bygoh at genting dot com dot my]

------- Additional Comments From bygoh at genting dot com dot my  2004-12-14 10:03 -------
Have been trying to upgrade to a newer version of gcc (3.3.3 and above). But I 
am getting an error during compilation:

checking whether the C compiler ( /usr/byg/src/bld-gcc/gcc/xgcc -B/usr/byg/src/b
ld-gcc/gcc/ -B/usr/local/gcc-3.3.4/i386-pc-sco3.2v5.0.5/bin/ -B/usr/local/gcc-3.
3.4/i386-pc-sco3.2v5.0.5/lib/ -isystem /usr/local/gcc-3.3.4/i386-pc-sco3.2v5.0.5
/include -O2 -O2 ) works... no
configure: error: installation or configuration problem: C compiler cannot creat
e executables.
gmake: *** [configure-target-libiberty] Error 1

Any idea how to get past this?

Configured and built with:
$ configure --prefix=/usr/local/gcc-3.3.4 --enable-languages="c++"
$ gmake CFLAGS="-O2" LANGUAGES="c c++"

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18713

[Bug target/18713] Large program size due to uninitialised global data

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2005-04-04 14:43 -------
No useful feedback in 3 months.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |RESOLVED
         Resolution|                            |INVALID


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=18713