Internal Architecture of Java Compiler [closed]

Answer 1

Some basic steps:

1. parse: Reads a set of *.java source files and maps the resulting token sequence into AST (Abstract Syntax Tree)-Nodes.
2. enter: Enters symbols for the definitions into the symbol table.
3. process annotations: If Requested, processes annotations found in the specifed compilation units.
4. attribute: Attributes the Syntax trees. This step includes name resolution, type checking and constant folding.
5. flow: Performs dataflow analysis on the trees from the previous step. This includes checks for assignments and reachability.
6. desugar: Rewrites the AST and translates away some syntactic sugar.
7. generate: Generates Source Files or Class Files.

In more details:

1. Lex - Break the source file into individual words, or tokens.
2. Parse - Analyze the phrase structure of the program.
3. Semantic Actions - Build a piece of abstract syntax tree corresponding to each phrase.
4. Semantic Analysis - Determine what each phrase means, relate uses of variables to their definitions, check types of expressions, request translation of each phrase.
5. Frame Layout - Place variables, function-parameters, etc. into activation records (stack frames) in a machine-dependent way.
6. Translate - Produce intermediate representation trees (IR trees), a notation that is not tied to any particular source language or targetmachine architecture.
7. Canonicalize - Hoist side effects out of expressions, and clean up conditional branches, for the convenience of the next phases.
8. Instruction Selection - Group the IR-tree nodes into clumps that correspond to the actions of target-machine instructions.

9. Control Flow Analysis - Analyze the sequence of instructions into a control flow graph that shows all the possible flows of control the program might follow when it executes.

10. Dataflow Analysis - Gather information about the flow of information through variables of the program; for example, liveness analysis calculates the places where each program variable holds a still-needed value (is live).

11. Register Allocation - Choose a register to hold each of the variables and temporary values used by the program; variables not live at the same time can share the same register.

12. Code Emission - Replace the temporary names in each machine instruction with machine registers.

There is a nice book:

Modern Compiler Implementation in Java

You may want to look inside javac code:

Javac Documentation

OpenJDK source code

Hacker's guide to javac

Don't Panic! To help newcomers to javac navigate their way around the code base

JVM JLS