cortex-m3(gcc.4.6.3)

[Umesh Kalappa <umesh dot kalappa0 at gmail dot com>]

Dear Group,

The below asm is generated for target  cortex-m3 (gcc-4.6.3)

main:
    @ args = 0, pretend = 0, frame = 0
    @ frame_needed = 0, uses_anonymous_args = 0
    push {r3, r4, r5, lr}
    bl  vAlgTNoOptimize
    movs r0, #170
    bl  vFnCall
    bl  vAlgTOptimize
    ldr r4, .L22
    add r5, r4, #88
.L20:
    ldr r1, [r4, #4]!
    movs r0, #2
    ldr r2, [r4, #88]
    bl  ucCheckResult
    cbnz r0, .L19
    cmp r4, r5
    bne .L20
    ldr r0, .L22+4
    ldr r1, .L22+8
    pop {r3, r4, r5, lr}
    b   printf
.L19:
    ldr r0, .L22+12
    ldr r1, .L22+8
    pop {r3, r4, r5, lr}
    b   printf

>From the   main  prologue ,we can see that the instruction  " push
{r3, r4, r5, lr} " ,where we are saving r3-r5 and lr and restoring the
same in the epilogue,saving r4,r5 (callee save ) and
lr(call_used_register) make sense here w.r.t ARM EABI,But i didn't get
why we save r3 here and where we don't use r3 in the function ???.

Or i'm missing something here  ???

Thanks
~Umesh