[Bug ada/20797] New: Code gen creating out-of-bounds addresses on legit code

[nick at sqrt dot co dot uk]

Looking at GCC 4.0 20050318, and configuring as a cross-compiler for ARM/Linux
thusly:
 
$ mkdir arm-linux ; cd arm-linux
$ ../configure --prefix=/opt/gcc-linux --target=arm-linux-elf
--enable-languages=c,ada

Once the gnat1 binary is built, just type this from the gcc/ada directory.

$ ../../arm-linux/gcc/gnat1 nlists.adb -O2 -o nlists.s -gnatpg

Turning off optimisation makes no difference to the resulting problem.


The compiled version of Nlists::First() results in:

nlists__first:
        @ args = 0, pretend = 0, frame = 0, outgoing = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
        cmp     r0, #0
        ldrne   r2, .L320
        mov     r1, #1191182336
        ldrne   r3, [r2, #0]
        add     ip, r0, r0, asl #1
        add     r1, r1, #8781824
        add     r1, r1, #35840
        addne   r3, r3, ip, asl #2
        ldrne   r0, [r3, r1]
        @ lr needed for prologue
        bx      lr
.L320:
        .word   nlists__lists__tableX

The problem I see is an out-of-bounds memory access here:
        ldrne   r0, [r3, r1]

FYI, on my machine:
   R1 == 0x47868c00
   R3 == 0xb97d3a9c

Here, R3 points to a legitimate memory address
Surely R1 is a little large ?

-- 
           Summary: Code gen creating out-of-bounds addresses on legit code
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: ada
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: nick at sqrt dot co dot uk
                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: arm-linux-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20797