Compiler Structure

A classical compiler can be broken into four phases:

scanner

converts characters to tokens (aka lexemes)

parser

takes sequences of tokens to recognize sentences (statements)

semantic processing

checks consistency of meaning across statements (for example, variable usage, function arity with call, type consistency)

code generation

complexity of this stage can vary widely, so it is broken down further as follows:

intermediate code generation

simple code generation based on translation rule for each construct of the language (avoid premature optimization)

machine independent optimization

remove redundant code arising as a consequence of previous phase-basic block construction, common sub-expression elimination

native code generation

simple generation of target machine code using a translation rule from each intermediate construct to a sequence of machine instructions

machine dependent optimization

optimization of the code from the previous phase-usually by peephole.