optimization/8896: '-mcpu=xscale -fno-strict-aliasing -O2' generates wrong code

[enrico dot scholz at informatik dot tu-chemnitz dot de]

>Number:         8896
>Category:       optimization
>Synopsis:       '-mcpu=xscale -fno-strict-aliasing -O2' generates wrong code
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          wrong-code
>Submitter-Id:   net
>Arrival-Date:   Tue Dec 10 15:46:01 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     Enrico Scholz
>Release:        gcc-3.2.1
>Organization:
>Environment:
Reading specs from /usr/lib/gcc-lib/arm-linux/3.2.1/specs
Configured with: ../configure --host=i386-redhat-linux --target=arm-linux --prefix=/usr --mandir=/usr/share/man --disable-checking --with-cpu=strongarm1100 --enable-languages=c
Thread model: posix
gcc version 3.2.1
>Description:
The arm-linux-gcc miscompiles XScale linux-kernels (the attached testcase is derived from fs/binfmt_elf.c of linux-2.5.49 + various ARM patches).

Because of other environment-problems, I do not have a complete test-program, but the miscompilation is visible in the disassembled .o-file. The interesting code is:

 ---- objdump -d binfmt_elf.o
  70:   e3a04002        mov     r4, #2  ; 0x2
  7c:   e0844004        add     r4, r4, r4
  84:   e1a0e004        mov     lr, r4
  e0:   e50be0b0        str     lr, [fp, -#176]


These statements are the result of:

|  60          elf_info[ei_index++] =  3; ...

which is wrong. Other ELF-tags are incorrect too, but this is the most obvious one.
>How-To-Repeat:
Compile the testprogram with

| arm-linux-gcc -O2 -fno-strict-aliasing -mcpu=xscale -c binfmt_elf.c

Watch the output with 'objdump -d binfmt_elf.o'
>Fix:

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