A trace tree is a data structure that is used in the runtime compilation of programming code. Trace trees are used in a type of 'just in time compiler' that traces code executing during hotspots and compiles it. When those hotspots are entered again the compiled code is run instead. It traces each statement executed, including within other function calls, and this entire execution path is compiled. This is different from compiling individual functions. The compiler can gain more information for the optimizer to operate on, and remove some of the overhead of the calls. Anytime the compiled code makes a call to code that has not been jitted, the interpreter is called to continue.
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Trace tree Wikipedia(Text) CC BY-SA