facebook/hhvm — pull request #2836 by Aatch (2014-06-02 23:27:18+00:00)
Title: Add option to explicitly turn on tracing

Sometimes it is useful to be able to use tracing without using a debug build. Clearly somebody already thought of this, since there is a `USE_TRACE` define already floating around. This adds an option to CMake so you can pass `-DENABLE_TRACE=1` to `cmake` and get tracing.

Good for initially debugging things without having to do a full debug build.