[arm-gnu] undefined instruction

[Carlo Caione]

On Wed, May 16, 2012 at 1:04 AM, Carlos O'Donell
<carlos_odonell at mentor.com> wrote:

> What did you use to get this disassembly?

arm-none-aebi-gdb in eclipse. Without eclipse is (obviously :) the same:

(gdb) disassemble
Dump of assembler code for function strlen:
=> 0x40205c84 <+0>:    beq    0x40205d18 <memcpy>
   0x40205c88 <+4>:            ; <UNDEFINED> instruction: 0xf03fe03a
   0x40205c8c <+8>:    andeq    r0, r0, r6
   0x40205c90 <+12>:    andeq    r0, r0, r4
   0x40205c94 <+16>:    andeq    r0, r0, r7
   0x40205c98 <+20>:    andeq    r0, r0, sp, lsl r0
   0x40205c9c <+24>:    ldrdmi    r0, [r0], -r3
   0x40205ca0 <+28>:            ; <UNDEFINED> instruction: 0xffffffff
End of assembler dump.

> When you compile with -save-temps what does the output assembly look like before being assembled?

.section        .text.strlen,"ax",%progbits
        .align  2
        .global strlen
        .type   strlen, %function
strlen:
.LFB83:
        .loc 1 223 0
        .cfi_startproc
        @ args = 0, pretend = 0, frame = 0
        @ frame_needed = 0, uses_anonymous_args = 0
        @ link register save eliminated.
.LVL34:
        .loc 1 223 0
        mov     r3, r0  @ ivtmp.163, s
.LVL35:
.L36:
        .loc 1 226 0 discriminator 1
        mov     r2, r3  @ sc, ivtmp.163
.LVL36:
        add     r3, r3, #1      @ ivtmp.163, ivtmp.163,
.LVL37:
        ldrb    r1, [r2, #0]    @ zero_extendqisi2      @ MEM[base:
sc_1, offset: 0B], MEM[base: sc_1, offset: 0B]
        cmp     r1, #0  @ MEM[base: sc_1, offset: 0B],
        bne     .L36    @,
        .loc 1 229 0
        rsb     r0, r0, r2      @, s, sc
.LVL38:
        bx      lr      @
        .cfi_endproc
.LFE83:
        .size   strlen, .-strlen

This is the disassebly of the object file:

Disassembly of section .text.strlen:

00000000 <strlen>:
   0:   e1a03000        mov     r3, r0
   4:   e1a02003        mov     r2, r3
   8:   e2833001        add     r3, r3, #1
   c:   e5d21000        ldrb    r1, [r2]
  10:   e3510000        cmp     r1, #0
  14:   1afffffa        bne     4 <strlen+0x4>
  18:   e0600002        rsb     r0, r0, r2
  1c:   e12fff1e        bx      lr


> It might be that the mapping symbols are missing and your disassembling constant pool data.
>
> What are the .gnu_attribute flags for the object file?

I don't have any flags (If I have correctly understood what you mean).

--
Carlo