[mikeash]

I don't think it is apples and oranges. Here's my next example:

    int ComputeStuff(int *value) {
        if(value == NULL) {
            long and complex computation for a NULL value
            return result
        } else {
            long and complex computation using the data pointed to by value
            return result
        }
    }

Then I call it from somewhere else like so:

    // NOTE: value must be non-NULL
    void DoStuff(int *value) {
        int pointedTo = *value;
        // do some work with pointedTo
        int computedResult = ComputeStuff(value);
        // do some more work with whatever
    }

Now, are you saying the compiler should not take advantage of the fact that it knows value is non-NULL at this particular call site and eliminate half of the code in this situation?