Phases of Compiler

Before talking about phases of compiler let me try to give an idea of Phases.

• Phases: Phases are the logically interrelated operation that takes source program in one representation and produces output in another representation.

• There are two major phases of a compiler:

  • Analysis Phase:

    • Machine independent
    • Language dependent
    • Analysis phase creates an intermediate representation from the given source code.

  • Synthesis Phase:

    • Machine dependent
    • Language independent
    • Synthesis phase creates an equivalent target program from the intermediate representation.

• Lexical Analyzer: It is also called Scanner.

  • It takes the output of the preprocessor as the input which is in a pure high-level language. It reads the characters from the source program and groups them into lexemes (sequence of characters that “go together”). Each lexeme corresponds to a token. Tokens are defined by regular expressions which are understood by the lexical analyzer. It also removes lexical errors (for e.g., erroneous characters), comments, and white space.
  • This is Analysis Phase.

• Syntax Analyzer: It is also called Parser. Because It constructs Parse Tree.

  • It takes all tokens one by one and uses Context Free Grammer to construct the parse tree.
  • This is Analysis Phase.

• Semantic Analyzer: It verifies the Parse tree which we get from Syntax Analyzer.

  • It checks if it is meaningful or not, and produces a verified parse tree.
  • It also checks type checking, label checking, and flow control checking.
  • This is Analysis Phase.

• Intermediate Code Generator: It generate intermediate code.

  • This phase is bridges the analysis and synthesis phase of translation.
  • In this phase, we convert our code into low-level language.

  

  

• Code Optimizer: It transfers code so that it consumes fewer resources and produces more speed. The meaning of the code being transformed is not altered.

  • Optimization can be categorized into two types:
    • Machine independent
    • Machine dependent

• Target Code Generator: This is the final stage of compilation.

  • It takes the output of Code Optimizer and converts it into the sequence of relocatable machine code.

• Note: Your suggestion and feedback are welcome.