flowchart.md

Optimix Compiler: Project Architecture

1. Problem Statement

Many students learn Compiler Design using automated tools (like Flex and Bison), which hide the actual internal working of a compiler.

The Main Problem is to understand what actually happens inside a compiler. Solution: To solve this, the Optimix project builds a compiler completely from scratch using C++. It demonstrates:

1. Lexing & Parsing: Reading code without external tools.
2. Simulation: Running code directly (Interpreter).
3. Optimization: Making code faster using advanced math (SSA Form).

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2. Detailed System Flowchart

This diagram represents the complete lifecycle of a program in Optimix, inspired by standard compiler design phases.

graph TD
    %% Styles
    classDef phase fill:#e3f2fd,stroke:#1565c0,stroke-width:2px,rx:10,ry:10;
    classDef artifact fill:#fff3e0,stroke:#e65100,stroke-width:2px,stroke-dasharray: 5 5;
    classDef error fill:#ffebee,stroke:#c62828,stroke-width:2px;
    classDef memory fill:#f3e5f5,stroke:#7b1fa2,stroke-width:2px;

    %% Source
    User([User]) --> Source["Source Code (.optx)"]
    
    %% Phase 1: Lexical Analysis
    subgraph "Phase 1: Lexical Analysis (Lexer)"
        Source --> ReadChar[Read Characters]
        ReadChar --> RmWS[Remove Whitespace]
        RmWS --> Tokenize[Generate Tokens]
        Tokenize --> LexErr{"Valid?"}
        LexErr -- No --> ErrHandler[Error Handling]
        LexErr -- Yes --> Tokens["Token Stream"]
    end

    %% Phase 2: Syntax Analysis
    subgraph "Phase 2: Syntax Analysis (Parser)"
        Tokens --> CheckGrammar[Check Grammar Rules]
        CheckGrammar --> BuildAST["Build Parse Tree (AST)"]
        BuildAST --> SynErr{"Syntax OK?"}
        SynErr -- No --> ErrHandler
        SynErr -- Yes --> AST["Abstract Syntax Tree"]
    end
    
    %% Symbol Table Interaction
    Tokens -.-> SymTable[("Symbol Table")]
    AST -.-> SymTable

    %% Phase 3: Semantic & IR Gen
    subgraph "Phase 3: IR Generation (IRBuilder)"
        AST --> WalkAST[Walk AST]
        WalkAST --> GenTemps["Generate Temp Vars (t0, t1...)"]
        GenTemps --> GenQuad[Generate Quadruples/Instructions]
        GenQuad --> RawIR["Raw Intermediate Code"]
    end

    %% Phase 4: Optimization
    subgraph "Phase 4: Optimization (SSA)"
        RawIR --> AnalyzeCFG[Analyze Control Flow]
        AnalyzeCFG --> RenameVars["Rename Variables (SSA)"]
        RenameVars --> OptIR["Optimized IR (SSA Form)"]
    end

    %% Phase 5: Execution
    subgraph "Phase 5: Execution (IR Interpreter)"
        OptIR --> Fetch[Fetch Instruction]
        Fetch --> Decode{Decode OpCode}
        Decode --> Execute[Execute Logic/Math]
        Execute --> UpdateMem[Update Virtual Memory]
        UpdateMem --> Output[("Program Output")]
    end

    %% Styling classes
    class ReadChar,RmWS,Tokenize,CheckGrammar,BuildAST,WalkAST,GenTemps,GenQuad,AnalyzeCFG,RenameVars,Fetch,Decode,Execute,UpdateMem phase;
    class Source,Tokens,AST,RawIR,OptIR artifact;
    class ErrHandler error;
    class SymTable,Output memory;

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3. Module Breakdown

3.1 Lexical Analysis (The Scanner)

• Goal: specific reading of the source file.
• Actions:
  • Skips comments and whitespaces.
  • Converts characters i, n, t into keyword token int.
  • Converts 1, 0, 0 into number token 100.
• Output: A list of Token objects.

3.2 Syntax Analysis (The Parser)

• Goal: Understanding the structure.
• Actions:
  • Ensures code follows the language grammar.
  • Example: Checks that if is followed by (...) and then {...}.
  • Constructs the Abstract Syntax Tree (AST), which represents the code logic hierarchically.

3.3 IR Generation & Optimization

• Goal: Simplifying and Improving.
• Actions:
  • IR Builder: Flattens the tree into a linear list of simple instructions (like Assembly).
  • SSA Optimizer: Renames variables (x -> x_1, x_2) to make data flow explicit, simplifying further analysis.

3.4 Execution (The Virtual Machine)

• Goal: Running the program.
• Actions:
  • The IR Interpreter acts as a virtual CPU.
  • It fetches each IR instruction and performs the operation.
  • It manages a virtual memory space for variables.

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