NOP

    LLVM decided that the function wasn’t doing anything worthwhile and just removed it.

    Your for loop delay would become:

    1. $ cargo objdump --bin clocks-and-timers --release -- -d -no-show-raw-insn
    4. clocks_and_timers::delay::h711ce9bd68a6328f:
    5.  8000188:       push    {r4, r5, r7, lr}
    6.  800018a:       movs    r4, #0
    7.  800018e:       uxth    r5, r4
    8.  8000190:       bl      #4666
    9.  8000194:       cmp     r5, #150
    10.  8000198:       pop     {r4, r5, r7, pc}

    Now, test this: Compile the program in debug mode and run it, then compile the program in releasemode and run it. What’s the difference between them? What do you think is the main cause of thedifference? Can you think of a way to make them equivalent or at least more similar again?