target/8159: ARM/THUMB code uses sp as index register for automatic arrays
trauscher@loytec.com
trauscher@loytec.com
Mon Oct 7 08:06:00 GMT 2002
>Number: 8159
>Category: target
>Synopsis: ARM/THUMB code uses sp as index register for automatic arrays
>Confidential: no
>Severity: serious
>Priority: low
>Responsible: unassigned
>State: open
>Class: wrong-code
>Submitter-Id: net
>Arrival-Date: Mon Oct 07 08:06:00 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator: Thomas Rauscher
>Release: 3.2
>Organization:
LOYTEC electronics GmbH
>Environment:
System: Linux lexx 2.2.19 #3 Mon Nov 5 10:25:49 CET 2001 i686 unknown
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: arm-rtems-elf
configured with: ./configure --target=arm-rtems-elf --prefix=/usr/local --enable-languages=c,c++ --with-newlib
>Description:
The compiler sometimes uses "sp" as index register for
loading/storing automatic arrays.
Optimization must be enabled for the problem to appear.
>How-To-Repeat:
Edit the following file (x.c)
int f(int n)
{
int a[1];
return a[n];
}
Running the compiler yields:
arm-rtems-elf-gcc -v -c -O1 -save-temps -mthumb x.c
Reading specs from /usr/local/lib/gcc-lib/arm-rtems-elf/3.2/specs
Configured with: /tmp/arm/gcc-3.2/configure --target=arm-rtems-elf --prefix=/usr/local --enable-languages=c,c++ --with-newlib
Thread model: single
gcc version 3.2
/usr/local/lib/gcc-lib/arm-rtems-elf/3.2/cpp0 -lang-c -v -D__GNUC__=3 -D__GNUC_MINOR__=2 -D__GNUC_PATCHLEVEL__=0 -D__GXX_ABI_VERSION=102 -D__ELF__ -D__ELF__ -D__OPTIMIZE__ -D__STDC_HOSTED__=1 -Acpu=arm -Amachine=arm -D__ARM_ARCH_4T__ -D__APCS_32__ -D__ARMEL__ -D__THUMBEL__ -D__ELF__ -D__USES_INITFINI__ -D__thumb__ x.c x.i
GNU CPP version 3.2 (cpplib) (ARM/ELF)
ignoring nonexistent directory "/usr/local/arm-rtems-elf/sys-include"
#include "..." search starts here:
#include <...> search starts here:
/usr/local/lib/gcc-lib/arm-rtems-elf/3.2/include
/usr/local/arm-rtems-elf/include
End of search list.
/usr/local/lib/gcc-lib/arm-rtems-elf/3.2/cc1 -fpreprocessed x.i -quiet -dumpbase x.c -mthumb -O1 -version -o x.s
GNU CPP version 3.2 (cpplib) (ARM/ELF)
GNU C version 3.2 (arm-rtems-elf)
compiled by GNU C version 2.95.2 19991024 (release).
/usr/local/lib/gcc-lib/arm-rtems-elf/3.2/../../../../arm-rtems-elf/bin/as -mno-fpu -o x.o x.s
x.s: Assembler messages:
x.s:12: Error: lo register required -- `ldr r0,[r0,sp]'
The wrong assembly output is:
.file "x.c"
.text
.align 2
.global f
.thumb_func
.type f,function
f:
sub sp, sp, #4
lsl r0, r0, #2
ldr r0, [r0, sp] !!!!! This instruction fails to assemble
add sp, sp, #4
@ sp needed for prologue
bx lr
.Lfe1:
.size f,.Lfe1-f
.ident "GCC: (GNU) 3.2"
>Fix:
None known.
>Release-Note:
>Audit-Trail:
>Unformatted:
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