The movie was about gangs, and near the end of the movie, a lot of people die in a warehouse. Sorry I can’t remember more. It was years ago.
The song was (I’m pretty sure) called Wildflower (the Chinese word for wildflower). It had a female singer, and sparse acoustic guitar accomplishment. It was a solemn sounding song.
I’d love to hear it again, if I can find it.
This isn’t an answer, but maybe it’ll help. Perhaps you can narrow it down to the exact movie, and work from there.
100 Best Chinese Gang Movies
Haha I checked this very site this morning. Couldn’t find it. Thanks, though.