What are the target languages of the compilation principle T graph source language? For example.

The compiler itself is a piece of software. If the software is written in any language, such as C language, then C language is its representation language (commonly called implementation language). The function of compiling system is translation, which can equivalently translate a program written in a high-level language (i.e. the source language) into a program written in another low-level language (i.e. the target language).

For example:

A java compiler is implemented in C language, which can translate java programs into bytecode. Then the source language of the compiler is java, the target language is bytecode, and the presentation language is C.