Memory Layout in C

You're interviewing for an ML Engineer role at Qualcomm, working on model inference that runs on a DSP with a tight, well-defined memory map. Your interviewer hands you this small C program and asks you to reason about where each variable actually lives at runtime.

int global_counter = 10;

static int cached_threshold;

char *label = "qualcomm_dsp_model";

int compute_score(int input)
{
    int local_result;
    static int call_count;
    int *heap_buffer = malloc(sizeof(int) * 4);

    call_count = call_count + 1;
    local_result = input * global_counter;
    heap_buffer[0] = local_result;

    return heap_buffer[0];
}

int main(void)
{
    int stack_value = 42;
    int result = compute_score(stack_value);
    printf("%d
", result);
    return 0;
}

For each of these, say which memory region it lives in (stack, heap, initialized data segment, BSS, or read-only/text segment) and why: global_counter, cached_threshold, the label pointer itself versus the string it points to, local_result, call_count, the heap_buffer pointer itself versus what it points to, and stack_value. Also say what happens to call_count's value across multiple calls to compute_score, and why that differs from local_result.