What is the process for a movie getting a song written by a popular artist?

Question

Songs written for movies by well-known artists are quite common, with examples such as Hozier for Tarzan, Ellie Goulding for 50 Shades of Grey and Pink for Charlie's Angels, sometimes going as far as to reference the film within the song. These songs are then often released by the artist as a single, or part of an album.

I would assume this means that the rights to the song are kept by the original artist or writer, allowing them to make money from the song in their own right, and the property is leased by the movie production to be included within the movie.

My question is: how does this process usually work?

Would movie producers approach an artist who makes a particular style or genre of music that they are trying to include in the movie, and ask the artist to write a song to fit that, or would they approach a number of artists and ask for songs, then decide the best choice?

Would they be asked close to the beginning of production during the creative process in order to let the song influence the movie, or is it closer to the end of production and the song is then written to a specification to fit the feel of the movie?

Particularly considering that the songs are usually later released by the artist (or sometimes before the release of the movie), the song itself needs to be of a good quality and follow the structure of an actual song. Do the movie productions simply ask for a melody or hook that they can sample for the movie's score, which the artist then builds into a full song, or is the song written and the movie chooses the best parts from it?

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Note: I'm specifically asking about songs that are used within the movie itself as opposed to during the credits, such as the majority of James Bond themes. Also, not songs that already exist and are included in a film years later, just songs that are created specifically for the purpose of being included in a movie.

Also, if any of my assumptions are incorrect, I would be happy to change them, or if any of the sub-questions aren't answerable because there is no definitive answer I will remove them.

Answer 1

If you look at P!ink song you will see that this is regular song making process. It wasn't song made for movie.

The difference is that instead of making a decision at the production stage that the score will be written by particular artist (Like Zimmer/Huey Lewis),the director, producer, or studio exec will say, "You know what would be good? If we use this song in this place or this song to promote the whole movie." For example, when the Exec is from the same company that is involved in making a movie and producing the music, then he will say, "We have this new artist here, it would be nice if they did the song. We will write it to promote this movie".

Music per se is rarely pre-made for a movie. By this I mean that original score doesn't exist until some pre-cut of the movie is made. Then the chosen composer, musical supervisor or director sits down, watches the movie, and thinks about the music.

Sometimes directors/screenwriters have certain song attributed to certain scenes in a movie (like Tarantino does or when in BTTF Johnny B. Good), but this not something you are interested in.

So - people who can say something about music chosen for movie, choose from very large library of music and decide that some score need to be done specifically for this movie. Sometimes they decide that such song exists, but must be remade to better suit the movie (See Trent Reznor Immigrant Song cover). And they have A LOT of knowledge of music and artists (there are schools specifically for those) and they propose that, for example, King of MetalRock should make some songs.

With large corporations, like Sony, it's just easier, cheaper, and faster to write songs, get them to perform with one of the top 10 artist they have contract with, and just earn more money on the whole marketing machine. After all, it's two horses pulling one cart.