08-17-2017, 12:23 AM
simple code generator in compiler design
Code generation can be considered as the final phase of compilation. Through post code generation, optimization process can be applied on the code, but that can be seen as a part of code generation phase itself. The code generated by the compiler is an object code of some lower-level programming language, for example, assembly language. We have seen that the source code written in a higher-level language is transformed into a lower-level language that results in a lower-level object code, which should have the following minimum properties:
It should carry the exact meaning of the source code.
It should be efficient in terms of CPU usage and memory management.
We will now see how the intermediate code is transformed into target object code (assembly code, in this case).
Directed Acyclic Graph
Directed Acyclic Graph (DAG) is a tool that depicts the structure of basic blocks, helps to see the flow of values flowing among the basic blocks, and offers optimization too. DAG provides easy transformation on basic blocks. DAG can be understood here:
Leaf nodes represent identifiers, names or constants.
Interior nodes represent operators.
Interior nodes also represent the results of expressions or the identifiers/name where the values are to be stored or assigned.