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[Bug target/15781] New: ARM ELF - incorrectly aligned .comm data
- From: "gcc-bugzilla at gcc dot gnu dot org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 2 Jun 2004 18:19:34 -0000
- Subject: [Bug target/15781] New: ARM ELF - incorrectly aligned .comm data
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
Global data (.comm) are improperly aligned on 32-byte boundary.
As a result, 4-byte variables occupy 32 bytes - 78% memory loss.
Environment:
System: Linux hanum.cronyx.ru 2.4.18-5aspsmp #1 SMP Sat Jul 6 19:58:36 EEST 2002 i686 unknown
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: /soft/gnu/gcc-3.3.3/configure --prefix=/usr/local/gcc333 --disable-nls --enable-languages=c,c++,ada,java --enable-shared
How-To-Repeat:
Compile and link the following file:
long x;
long y;
_start(){}
Look at "nm -n" output:
00008000 T _start
00008114 A __bss_start
00008114 A __bss_start__
00008114 D __data_start
00008114 A _edata
00008120 B x
00008140 B y
00008144 A __bss_end__
00008144 A _bss_end__
00008144 A _end
00008144 A __end__
00080000 ? _stack
You can see that "x" variable takes 0x20 bytes.
------- Additional Comments From vak at hanoi dot cronyx dot ru 2004-06-02 18:19 -------
Fix:
GCC generates ".comm" directive with alignment in bits,
while GAS expects alignment in bytes. Fix gcc/config/arm/elf.h,
macro ASM_OUTPUT_ALIGNED_COMMON() - divide ALIGN by 8.
--
Summary: ARM ELF - incorrectly aligned .comm data
Product: gcc
Version: 3.3
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: vak at hanoi dot cronyx dot ru
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=15781