Undefined reference to 'function_name' in ARM assembly

Question

I'm attempting to put together some relatively simple code that uses two functions, fact and exp. However, whenever I try to branch to either of them, I get an error that reads: undefined reference to 'fact' and undefined reference to 'exp'. I tried adding .global fact and .global exp to the top of the file, but that didn't help. Here's my code:

.text
.global main
.extern printf

main:
    ldr x2,=x // load 'x' -> x value
    ldr d2,[x2]
    ldr x2,=n  // load 'n' -> stopping point
    ldr x3,[x2]
    mov x2,#1 // set i/exp value to 1
    scvtf d1,x2  // default d1 (return value) to 1.0
loop:
    subs xzr, x3, x2
    ble done
    sub sp, sp, #16
    str x2,[sp] // save the value of x2 first
    sub x7, x2, #1

    bl fact

    ldr x2,[sp]   // get original x2 value back
    add sp, sp, #16
    mov x5, #0
    fmov d4, d2

.func fact
    mul x2, x2, x7
    sub x7, x7, #1
    cbnz x7,fact
    mov x4, x2
    br x30
.endfunc

.func exp
    fmul d4, d4, d4
    add x5, x5, #1
    cmp x5, x2

    bl exp

    br x30
.endfunc

done:
    // done

.data
    n:
    .quad 5
    x:
    .double 1.45
.end

Answer 1

In the GNU assembler, .func and .endfunc only serve to emit debugging info. They don't take the place of actually defining a label. (Nor do they emit any prologue or epilogue code, which might have been your next guess.)

So you should simply write, as for your other entry points:

fact:
    mul x2, x2, x7
    // ...

You might as well omit .func/.endfunc unless you are going to also produce proper debugging info for the rest of your code, which is usually not worth the trouble for handwritten assembly.