how to compiler generates the bytecode,let me show you with the simplest words.

think of the class below:

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public class HelloWorld {
    public static void main(String[] args) {
        System.out.println("Hello, World!");
    }
}

  • Step 1: Parse: Reads a set of *.java source files and maps the resulting token sequence into AST (Abstract Syntax Tree)-Nodes.

  • Step 2: Enter: Enters symbols for the definitions into the symbol table.

  • Step 3: Process annotations: If Requested, processes annotations found in the specified compilation units.

  • Step 4: Attribute: Attributes the Syntax trees. This step includes name resolution, type checking and constant folding.(folding eg:"a=1+2" is optimized to "a=3")

  • Step 5: Flow: Performs dataflow analysis on the trees from the previous step. This includes checks for assignments and reachability.

  • Step 6: Desugar: Rewrites the AST and translates away some syntactic sugar.

  • Step 7: Generate: Generates ‘.Class’ files.

finally,The AST for our example code looks something like this:

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CompilationUnit
 └── TypeDeclaration (class: HelloWorld)
     └── MethodDeclaration (public static void main(String[] args))
         └── Statement (System.out.println("Hello, World!"))

if you want more details,step to com.sun.tools.javac.main.JavaCompiler and find out


本文作者：oldmee
本文链接：https://oldmee.github.io/2022/05/02/process-of-the-sourcecode-compile-into-bytecode-of-Java/
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