some quesion about assembly when calling fork

[loody]

Dear all:
i copy the assembly code as below, I use uclibc.

       if ((pid = fork()) < 0) {
    84b4:       ebffffb5        bl      8390 <.text-0x48>
    84b8:       e1a03000        mov     r3, r0
    84bc:       e50b3010        str     r3, [fp, #-16]    xx1
    84c0:       e51b3010        ldr     r3, [fp, #-16]    xx2
    84c4:       e3530000        cmp     r3, #0  ; 0x0
    84c8:       aa000002        bge     84d8 <main+0x3c>
                printf("fork error");
    84cc:       e59f0040        ldr     r0, [pc, #64]   ; 8514 <.text
+0x13c>
    84d0:       ebffffba        bl      83c0 <.text-0x18>
    84d4:       ea00000b        b       8508 <main+0x6c>

why we store r3 and ld it back at the same place in xx1 and xx2.
does that have any relationship with fork?
appreciate your help,
miloody