Compilers of the 21 st Century

. Overall structure of almost all the compilers is similar to the structure we have discussed

. The proportions of the effort have changed since the early days of compilation

. Earlier front end phases were the most complex and expensive parts.

. Today back end phases and optimization dominate all other phases. Front end phases are typically a small fraction of the total time

Front end design has been almost mechanized now. Excellent tools have been designed that take in the syntactic structure and other specifications of the language and generate the front end automatically