[Bug ld/3869] New: The mapping behavior for small data of the ld for Pow

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[Bug ld/3869] New: The mapping behavior for small data of the ld for Pow

From:	tanaka at personal-media dot co dot jp
Subject:	[Bug ld/3869] New: The mapping behavior for small data of the ld for PowerPC, from COMMON section to bss section.
Date:	15 Jan 2007 13:03:07 -0000

Hello,

By using ld for PowerPC, a small size variable in the COMMON section is mapped
to the bss section.
But By using ld for MIPS, a small size variable in the COMMON section is mapped
to the sbss section.

I think the behavior of the ld for MIPS is correct, and PowerPC's is something
wrong.

Below is a sample code.
/******* a.h ***********/
extern int      a1[1];
int b( void );
/******* a.c ***********/
#include "a.h"

int     a1[1];
void __start()
{
        b();
}
/******* b.c ***********/
#include "a.h"
int b( void )
{
        if (a1[1] == 0) {
                return 0;
        }
        return 1;
}
/******* mk.rc *********/
#!/bin/sh

export LANG=C

### powerpc ###
ppcgcc="/work/te/tool/build/gnu/gcc-4.1.1-linux/Linux-i686.ppclinux/./gcc/xgcc"
ppcgcc="$ppcgcc
-B/work/te/tool/build/gnu/gcc-4.1.1-linux/Linux-i686.ppclinux/./gcc/"
ppcgcc="$ppcgcc -B/work/te/tool/Linux-i686.ppclinux/powerpc-unknown-linux/bin/"
        
$ppcgcc -msdata=sysv -G 8 -c -o a.ppc.o a.c
$ppcgcc -msdata=sysv -G 8 -c -o b.ppc.o b.c
$ppcgcc -msdata=sysv -G 8 -r -Wl,-d -nostdlib -o c.ppc.out a.ppc.o b.ppc.o

ppcobjdump="/work/te/tool/Linux-i686.ppclinux/bin/powerpc-unknown-linux-objdump"

$ppcobjdump --all-headers a.ppc.o > a.ppc.o.odp
$ppcobjdump --disassemble a.ppc.o >> a.ppc.o.odp

$ppcobjdump --all-headers b.ppc.o > b.ppc.o.odp
$ppcobjdump --disassemble b.ppc.o >> b.ppc.o.odp

$ppcobjdump --all-headers c.ppc.out > c.ppc.out.odp
$ppcobjdump --disassemble c.ppc.out >> c.ppc.out.odp

### mips ###
mipsgcc="/work/te/tool/build/gnu/gcc-4.1.1-linux/Linux-i686.mipslinux/./gcc/xgcc"
mipsgcc="$mipsgcc
-B/work/te/tool/build/gnu/gcc-4.1.1-linux/Linux-i686.mipslinux/./gcc/"
mipsgcc="$mipsgcc 
-B/work/te/tool/Linux-i686.mipslinux/mips64el-unknown-linux/bin/"

$mipsgcc -O1 -c -o a.mips.o a.c
$mipsgcc -O1 -c -o b.mips.o b.c
$mipsgcc -O1 -r -Wl,-d -nostdlib -o c.mips.out a.mips.o b.mips.o

mipsobjdump="/work/te/tool/Linux-i686.mipslinux/bin/mips64el-unknown-linux-objdump"

$mipsobjdump --all-headers a.mips.o > a.mips.o.odp
$mipsobjdump --disassemble a.mips.o >> a.mips.o.odp

$mipsobjdump --all-headers b.mips.o > b.mips.o.odp
$mipsobjdump --disassemble b.mips.o >> b.mips.o.odp

$mipsobjdump --all-headers c.mips.out > c.mips.out.odp
$mipsobjdump --disassemble c.mips.out >> c.mips.out.odp

$ppcgcc -v
$mipsgcc -v
/***********************************************************/

Below is the result of the execution of "mk.rc".
/***********************************************************/
address@hidden:/work/test/scomm/$ ./mk.rc 
Reading specs from
/work/te/tool/build/gnu/gcc-4.1.1-linux/Linux-i686.ppclinux/./gcc/specs
Target: powerpc-unknown-linux
Configured with: ../gcc-4.1.1/configure
--prefix=/work/te/tool/Linux-i686.ppclinux --target=powerpc-unknown-linux
--enable-languages=c --enable-threads=no
Thread model: single
gcc version 4.1.1
Reading specs from
/work/te/tool/build/gnu/gcc-4.1.1-linux/Linux-i686.mipslinux/./gcc/specs
Target: mips64el-unknown-linux
Configured with: ../gcc-4.1.1/configure
--prefix=/work/te/tool/Linux-i686.mipslinux --target=mips64el-unknown-linux
--enable-languages=c --enable-threads=no
Thread model: single
gcc version 4.1.1
address@hidden:/work/test/scomm/$ 
/***********************************************************/

Below is the output files for PowerPC.
/******** a.ppc.o.odp **********/
SYMBOL TABLE:
               .
00000004       O *COM*  00000004 a1

/******** b.ppc.o.odp **********/
SYMBOL TABLE:
               .
00000000         *UND*  00000000 a1

RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE 
0000000e R_PPC_SDAREL16    a1+0x00000004

Disassembly of section .text:

00000000 <b>:
   0:   94 21 ff e0     stwu    r1,-32(r1)
   4:   93 e1 00 1c     stw     r31,28(r1)
   8:   7c 3f 0b 78     mr      r31,r1
   c:   80 0d 00 04     lwz     r0,4(r13)
  10:   2f 80 00 00     cmpwi   cr7,r0,0
  14:   40 9e 00 10     bne-    cr7,24 <b+0x24>
               .
               .

/******** c.ppc.out.odp **********/
SYMBOL TABLE:
               .
00000000 l    df *ABS*  00000000 b.c
00000030 g     F .text  00000044 b
00000000 g     O .bss   00000004 a1          <===== .sbss ????
00000000 g     F .text  00000030 __start


RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE 
00000014 R_PPC_REL24       b
0000003e R_PPC_SDAREL16    a1+0x00000004

Disassembly of section .text:

00000000 <__start>:
   0:   94 21 ff f0     stwu    r1,-16(r1)
              .

00000030 <b>:
  30:   94 21 ff e0     stwu    r1,-32(r1)
  34:   93 e1 00 1c     stw     r31,28(r1)
  38:   7c 3f 0b 78     mr      r31,r1
  3c:   80 0d 00 04     lwz     r0,4(r13)
  40:   2f 80 00 00     cmpwi   cr7,r0,0
  44:   40 9e 00 10     bne-    cr7,54 <b+0x24>
              .
/***********************************************************/

Below is the output files for MIPS.
/******** a.mips.o.odp **********/
SYMBOL TABLE:
              .
00000004       O *COM*  00000008 a1

/******** b.mips.o.odp **********/
SYMBOL TABLE:
              .
00000000 g     F .text  0000001c b
00000000         *UND*  00000000 a1


RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE 
              .
0000000c R_MIPS_GOT_DISP   a1
              .
          
Disassembly of section .text:

00000000 <b>:
   0:   3c030000        lui     v1,0x0
   4:   00791821        addu    v1,v1,t9
   8:   24630000        addiu   v1,v1,0
   c:   8c620000        lw      v0,0(v1)
  10:   8c420004        lw      v0,4(v0)
  14:   03e00008        jr      ra
              .
/******** c.mips.out.odp **********/
SYMBOL TABLE:
              .
00000040 g     F .text  0000001c b
00000000 g     O .sbss  00000004 a1        <============= .sbss
00000000 g     F .text  00000034 __start


RELOCATION RECORDS FOR [.text]:
OFFSET   TYPE              VALUE 
              .
0000004c R_MIPS_GOT_DISP   a1

Disassembly of section .text:

00000000 <__start>:
   0:   27bdfff0        addiu   sp,sp,-16
              .

00000040 <b>:
  40:   3c030000        lui     v1,0x0
  44:   00791821        addu    v1,v1,t9
  48:   24630000        addiu   v1,v1,0
  4c:   8c620000        lw      v0,0(v1)
  50:   8c420004        lw      v0,4(v0)
  54:   03e00008        jr      ra
/***********************************************************/

Best regards.
tanaka
-----------------------------------------------------------------------------------

-- 
           Summary: The mapping behavior for small data of the ld for
                    PowerPC, from COMMON section to bss section.
           Product: binutils
           Version: 2.17
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
        AssignedTo: unassigned at sources dot redhat dot com
        ReportedBy: tanaka at personal-media dot co dot jp
                CC: bug-binutils at gnu dot org
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet: powerpc-unknown-linux


http://sourceware.org/bugzilla/show_bug.cgi?id=3869

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