target/6920: gcc-arm-elf v3.1 Wrong assembler code with -mthumb -Os (-O2)

[omakarenko@cyberplat.ru]

>Number:         6920
>Category:       target
>Synopsis:       gcc-arm-elf v3.1 Wrong assembler code with -mthumb -Os (-O2)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Mon Jun 03 06:26:03 PDT 2002
>Closed-Date:
>Last-Modified:
>Originator:     omakarenko@cyberplat.ru
>Release:        unknown-1.0
>Organization:
>Environment:
Host: linux-x86
Target: arm-elf
Version: GCC 3.1 (arm/elf)
compiled by GNU C version 2.96 20000731 (RedHat Linux 7.3 2.96-110)
Configured with: /home/oleg/arm/tools/gcc/configure --target=arm-elf --enable-languages=c,c++
--disable-shared --disable-nls --with-gnu-as --with-gnu-ld --disable-checking
--with-multilibs --with-newlib --disable-newlib-io-float
Thread model:single
>Description:
The following simple file:

/* test.c stupid code to demonstrate the bug only */
void func(int d, char *x)
{
    char *a[32];
    if (a[d++] != (char *) 0)
    {
        x = a[d];
    }
    a[d] = x;
}

when compiled with

arm-elf-gcc -o test.Os.s -S -Os -mthumb test.c

produces code like:
ldr  r3, [r3, sp]

which is wrong for Thumb mode (sp can not be used in thumb mode)

gas then complains with "Error: lo register required"

-O2 and -O3 give the same result.

That is a duplicate report for c/6916. The attached file was somehow missed from the previous report. Sorry for that.
>How-To-Repeat:
compile test.c with -mthumb and -Os (or -O2, -O3) options
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted: