Ola

Ola is a toy programming language designed with a focus on modularity and learning, offering both an LLVM-based backend and a work-in-progress custom backend.

Dependencies

• LLVM 17.0.1 for compiler backend.
• spdlog for logging.
• CLI11 for command line parsing.

Features

• classes
  • access modifiers: public, private
  • constructors
  • single inheritance: :
  • polymorphism using vtables: virtual, pure, final
  • this and super keywords
• reference type: ref
• automatic type deduction: auto
• operators:
  • additive: +, -, +=, -=, ++, --
  • multiplicative: *, /, %, *=, /=, %=
  • relation: ==, !=, >, >=, <, <=
  • shift: >>, <<, >>=, <<=
  • bitwise: &, |, ^, ~, &=, |=, ^=
  • logic: &&, ||, !
• control statements: if else, switch, goto, ?:
• loop statements: for,foreach, while, do while, break, continue
• enums
• functions
  • overloading
  • attributes: inline, noinline, nomangling (equivalent to C++'s extern "C")
• arrays
• sizeof, length operators
• alias
• strings
• floats
• implicit casts
• scopes
• import statement
• standard library
• Backend architecture
  • LLVM Backend: Emits LLVM IR and supports LLVM optimization passes.
  • Custom Backend (Work in Progress):
    • Custom Intermediate Representation (IR) and Machine Intermediate Representation (MIR).
    • IR optimization passes
    • Early support for x86-64 code generation.
    • Missing features: proper stack layout and class support.

Structure

Ola consists of three main parts:

1. Ola Library:

   • A standard library for the Ola language, implemented in C and built as a static library to be used by the compiler. Currently, it includes the following files:
     • olaio.h
     • olamath.h
     • olaassert.h
     • olastring.h
     • olamemory.h

2. Ola Compiler:

• The core of the Ola project, divided into various stages for flexibility and modularity:
• Lexer: Tokenizes the source code.
• Import Processor: Processes import statements from the tokenized input.
• Parser: A recursive descent parser that constructs an Abstract Syntax Tree (AST) from processed tokens.
• Sema: Performs semantic analysis on the AST to ensure code correctness.
• Backend: After the frontend processing completes, the compilation process diverges into two backend paths:
  • LLVM Path:
    • LLVM Visitor: Transforms the AST into LLVM IR.
    • LLVM Optimizer: Applies LLVM optimization passes to the IR, based on the specified optimization level.
    • Compilation to assembly is done using clang -S command
  • Custom Backend Path:
    • IRVisitor: Transforms the AST into Ola's custom IR.
    • IROptimizer: Applies custom optimizations at the IR level.
    • MachineModule: responsible for lowering IR to MIR and finally to assembly.

3. Ola Tests:
   • A set of unit tests built with GoogleTest, covering Ola language features. They rely on Assert funtion from the std.assert import. Currently, two folder are maintained: LLVM tests and Custom backend tests with a goal of unifying them once the custom backend reaches the same capabilities as LLVM backend.

Usage

Command line options

• -h,--help: Print this help message and exit
• --astdump: Dump AST to output/log
• --testdebug: Print debug information during tests
• --test : used for running g-tests
• --Od : No optimizations
• --O0 : Same as --Od
• --O1 : Optimize
• --O2 : Optimize more
• --O3 : Optimize even more
• -i ... : Input files
• -o : Output file
• --directory : Directory of project files
• --simple : input code in the form of a string

Samples

Currently to see the samples you can check the test folder: OlaTests/Tests/.