# Compilers: How To Make a Programming Language

Other compiler-related topics out of scope:
- What are programs anyway (Forth, LISP)
- Computation: Turing machines, lambda calculus
- Compiler optimization
- GC (motivated by LISP)

aesthetics:
- stay motivated; stick close to a c-like, imperative, procedural model because that's what people are used to

motivation / goals / what questions are we trying to answer:
- I want to be able to make a toy procedural language.
    - like C, Algol, JS, Lua, etc.
    - possible user motivations:
        - I want to make a game scripting language
        - I want to make a DSL for my job (and I want syntax highlighting!)
- I want to do simple static analysis of my projects

ok what do we want to cover
- classical compiler structure (lexer -> parser -> codegen)

|Star| Title                                 | Page |
|----|---------------------------------------|------|
|    | Phases of a Compiler                  | https://www.geeksforgeeks.org/phases-of-a-compiler/ |
|*   | Compiler Architecture                 | https://cs.lmu.edu/~ray/notes/compilerarchitecture/ |
|    | Compiler Design                       | https://www.tutorialspoint.com/compiler_design/compiler_design_phases_of_compiler.htm |
|    | Structure of a Compiler               | https://www.csd.uwo.ca/~mmorenom/CS447/Lectures/Introduction.html/node10.html |
|    | The Structure of a Compiler           | https://www.brainkart.com/article/The-Structure-of-a-Compiler_8121/ |
|    | Wikipedia: Compiler                   | https://en.wikipedia.org/wiki/Compiler |
|    | The Structure of a Compiler (slides)  | https://pages.cs.wisc.edu/~fischer/cs536.s08/lectures/Lecture04.4up.pdf |
|    | Wikipedia: Code Generation            | https://en.wikipedia.org/wiki/Code_generation_(compiler) |
|    | Intro to Code Generation              | https://cs.lmu.edu/~ray/notes/codegen/ |
|    | Code Generation                       | https://www.tutorialspoint.com/compiler_design/compiler_design_code_generation.htm |
|*?  | Phases of a Compiler                  | https://www.guru99.com/compiler-design-phases-of-compiler.html |
|*?  | Writing a C Compiler (Pt. 1)          | https://norasandler.com/2017/11/29/Write-a-Compiler.html |
|    | V: Phases of a Compiler               | https://www.youtube.com/watch?v=jE7f3sGLGVk |
|*   | V: Different Phases of Comp           | https://www.youtube.com/watch?v=TApMNhQPaCM |
|*   | V: Parser and Lexer (Pt. 1)           | https://www.youtube.com/watch?v=eF9qWbuQLuw |

- semantic analysis / type checking

|Star| Title                         | Page |
|----|-------------------------------|------|
|    | Wikipedia                     | https://en.wikipedia.org/wiki/Compiler#Front_end |
|    | Compiler Design - SA          | https://www.tutorialspoint.com/compiler_design/compiler_design_semantic_analysis.htm |
|*   | What is Semantic Analysis?    | https://home.adelphi.edu/~siegfried/cs372/372l8.pdf |
|*?  | SA in Compiler Design         | https://iq.opengenus.org/semantic-analysis-in-compiler-design/ |
|*?  | Implementation of SA          | https://pgrandinetti.github.io/compilers/page/implementation-semantic-analysis/ |
|*?  | What is SA in a Compiler?     | https://pgrandinetti.github.io/compilers/page/what-is-semantic-analysis-in-compilers/ |
|    | SA (Slides)                   | https://www.computing.dcu.ie/~davids/courses/CA4003/CA4003_Semantic_Analysis_2p.pdf |
|    | V: The Semantic Analysis!     | https://www.youtube.com/watch?v=j172YWmBk5A |
|    | V: Intro to Semantic Analysis | https://www.youtube.com/watch?v=cC8YRnDGMwI |
|    | V: Compiler Design SA         | https://www.youtube.com/watch?v=57U6pQRnSJA |
|    | V: Semantic Analysis: Intro   | https://www.youtube.com/watch?v=7pHmBEkeIdQ |

|Star| Title                            | Page |
|----|----------------------------------|------|
|    | Type Checking in Compiler Design | https://www.geeksforgeeks.org/type-checking-in-compiler-design/ |
|    | Type Checking (Slides)           | https://www.slideshare.net/dipongkersen81/type-checkingcompilier-design |
|    | What is Static Type Checking?    | https://www.tutorialspoint.com/what-is-static-type-checking |
|    | What is Dynamic Type Checking?   | https://www.tutorialspoint.com/what-is-dynamic-type-checking |
|    | Type Systems                     | https://www.csd.uwo.ca/~mmorenom/CS447/Lectures/TypeChecking.html/node1.html |
|    | V: Type Checking                 | https://www.youtube.com/watch?v=-TQVAKby6oI |

- modern compiler structures (IR / SSA, optimization)

| Title                                      | Page |
|--------------------------------------------|------|
| Modern Compiler                            | https://www.sciencedirect.com/topics/computer-science/modern-compiler |
| Modern Compiler Design (Book)              | https://www.cs.usfca.edu/~galles/compilerdesign/cimplementation.pdf |
| Modern Compiler Design (Different Book)    |http://160592857366.free.fr/joe/ebooks/ShareData/Modern%20Compiler%20Design%202e.pdf|
| Wikipedia (IR)                             | https://en.wikipedia.org/wiki/Intermediate_representation |
| Intermediate Representations               | https://cs.lmu.edu/~ray/notes/ir/ |
| Intermediate Representations in Comp Design| https://iq.opengenus.org/intermediate-representations-in-compiler-design/ |
| Intermediate Representation (Slides)       | https://www.cs.princeton.edu/courses/archive/spring03/cs320/notes/IR-trans1.pdf |
| Single Static Assignment (Slides)          | https://www.cs.cmu.edu/~fp/courses/15411-f08/lectures/09-ssa.pdf |
| Wikipedia (SSA)                            | https://en.wikipedia.org/wiki/Static_single_assignment_form |
| SSA w/ Examples                            | https://www.geeksforgeeks.org/static-single-assignment-with-relevant-examples/ |
| Understanding SSA Forms                    | https://blog.yossarian.net/2020/10/23/Understanding-static-single-assignment-forms |
| V: Anders Hejlsberg on Modern Comp. Construction | https://www.youtube.com/watch?v=wSdV1M7n4gQ |

- interpreters vs. JITs vs. AOTs vs. "transpilers"

| Title                                      | Page |
|--------------------------------------------|------|
| Wikipedia (Compiler)                               | https://en.wikipedia.org/wiki/Compiler |
| Wikipedia (Interpreter)                            | https://en.wikipedia.org/wiki/Interpreter_(computing) |
| Interpreters vs. Compilers                         | https://www.programiz.com/article/difference-compiler-interpreter |
| Compiler vs. Interpreter                           | https://www.geeksforgeeks.org/compiler-vs-interpreter-2/ |
| Compiler vs. Interpreter, What's the Difference?   | https://www.guru99.com/difference-compiler-vs-interpreter.html |
| Wikipedia (Transpiler [Source-to-source compiler]) | https://en.wikipedia.org/wiki/Source-to-source_compiler
| Compiling vs. Transpiling (Stack Overflow)         | https://stackoverflow.com/questions/44931479/compiling-vs-transpiling |
| Compiler vs. Transpiler                            | https://mohasinhaque23121.medium.com/compiler-vs-transpiler-a64c989607d7 |
| Compiling vs. Transpiling                          | https://dev.to/kealanparr/compiling-vs-transpiling-3h9i |
| What does a JIT do? (Stack Overflow)               | https://stackoverflow.com/questions/95635/what-does-a-just-in-time-jit-compiler-do |
| How is a JIT different than a normal compiler?     | https://www.tutorialspoint.com/How-is-JIT-compiler-different-from-normal-compiler   |
| JIT Compilation Explained                          | https://www.freecodecamp.org/news/just-in-time-compilation-explained/ |
| Wikpedia (JIT Compilation)                         | https://en.wikipedia.org/wiki/Just-in-time_compilation |

- executables and linkers

| Title                                      | Page |
|--------------------------------------------|------|
| Wikipedia (Linker)                             | https://en.wikipedia.org/wiki/Linker_(computing) |
| Intro to compiler, linker, and libraries (C++) | https://www.learncpp.com/cpp-tutorial/introduction-to-the-compiler-linker-and-libraries/ |
| Linker                                         | https://www.geeksforgeeks.org/linker/ |
| Differences Between Compilers and Linkers (Stack Overflow) | https://stackoverflow.com/questions/3831312/what-are-the-differences-between-a-compiler-and-a-linker |
| Beginner's Guide to Linkers | https://www.lurklurk.org/linkers/linkers.html |
| V: Compiling, Assembling, and Linking          | https://www.youtube.com/watch?v=N2y6csonII4 |
| V: How the Linker Combines Object Files        | https://www.youtube.com/watch?v=oXk87NRTL1Y |
| V: Assembler, Linker, and Loader (C)           | https://www.youtube.com/watch?v=cJDRShqtTbk |
| What is an executable file?                    | https://www.computerhope.com/jargon/e/execfile.htm |
| Wikipedia (Executable)                         | https://en.wikipedia.org/wiki/Executable |
| V: What are Executables?                       | https://www.youtube.com/watch?v=WnqOhgI_8wA |
| V: What is an EXE file?                        | https://www.youtube.com/watch?v=r5ldP1P1Rzc |

- regular expressions?
- regular languages / grammars / language structure / automata
- terminology?

the c compilation process
- translation units
- preprocessing -> (the whole compilation process) -> object files -> linking
- c compilation model is not in favor any more, don't like compiling all these files separately
- ABIs and FFI
- should maybe be in separate article

experts / consultants:
- Bill
- NeGate

## The actual progression

- Simple expression interpreter (parse and evaluate)
- Classical compiler construction (lex -> parse -> output), semantic analysis / type checking
    - motivation: complex structures! recursion! etc.
    - many of these resources exist and cover different aspects of the process in different ways
- Grammars and language structure
- Types of output (interpreter vs. AOT vs. JIT, etc.)
    - We can probably find resources on specific ones of these
- Modern phases (IR / SSA)
    - Mention WASM?
- The terrors of the real world
    - Executables, linkers, and debug info
    - Also debug info
    - The C ABI and FFI
    - Debug info
    - Codegen
        - Specifically: machine code generation, of reasonable quality
            - Note: not necessary for all "compilers"
        - Topics: register allocation, instruction selection, instruction scheduling
        - Some examples of optimization passes
        - There are not a lot of resources for this. Place a public TODO here?
- Appendix:
    - Grammar basics (BNF, EBNF)
        - Need not go into exhaustive detail on categories of grammars
    - C is not the only language
        - Brief summaries and examples of different language approaches:
            - LISP
            - Forth
            - Languages in the ML family
        - This could be a whole topic maybe

## Link dump

### Books

- Engineering a Compiler: 
    [Well liked]
    http://www.r-5.org/files/books/computers/compilers/writing/Keith_Cooper_Linda_Torczon-Engineering_a_Compiler-EN.pdf
- Compiler Design in C:
    [May have a full implementation inside]
    https://holub.com/goodies/compiler/compilerDesignInC.pdf
- Dragon Book: 
    [Potentially outdated -- mixed reviews]
    http://ce.sharif.edu/courses/94-95/1/ce414-2/resources/root/Text%20Books/Compiler%20Design/Alfred%20V.%20Aho,%20Monica%20S.%20Lam,%20Ravi%20Sethi,%20Jeffrey%20D.%20Ullman-Compilers%20-%20Principles,%20Techniques,%20and%20Tools-Pearson_Addison%20Wesley%20(2006).pdf

### Webpages

- lua grammar: http://lua-users.org/wiki/LuaGrammar
- pascal railroad diagrams: https://www.cs.utexas.edu/users/novak/grammar.html
- tons of links: https://github.com/aalhour/awesome-compilers
- expression parsing examples:
    - pratt parsing and recursive descent: https://journal.stuffwithstuff.com/2011/03/19/pratt-parsers-expression-parsing-made-easy/
    - dunno, not recursive descent: https://www.cs.rochester.edu/u/nelson/courses/csc_173/grammars/parsing.html
- gary bernhardt's compiler from scratch: https://www.destroyallsoftware.com/screencasts/catalog/a-compiler-from-scratch
- lambda calculus interpreter: https://justine.lol/lambda/
- chibicc (full, readable C compiler): https://github.com/rui314/chibicc
- A Compiler Writing Journey (has many pages/topics): https://github.com/DoctorWkt/acwj

#### From NeGate
- Near-Optimal Instruction Selection on DAGs: https://llvm.org/pubs/2008-CGO-DagISel.pdf
- The Design and Implementation of Gnu Compiler Generation Framework: https://www.cse.iitb.ac.in/~uday/courses/cs715-10/cs715-gcc-intro-handout.pdf
- Lecture Notes on Static Single Assignment Form: https://www.cs.cmu.edu/~rjsimmon/15411-f15/lec/10-ssa.pdf
- Simple and Efficient Construction of Static Single Assignment Form: https://pp.info.uni-karlsruhe.de/uploads/publikationen/braun13cc.pdf
- LLVM Greedy Register Allocator – Improving Region Split Decisions: https://llvm.org/devmtg/2018-04/slides/Yatsina-LLVM%20Greedy%20Register%20Allocator.pdf
- NULLSTONE Optimization Categories: ttp://www.nullstone.com/htmls/category.htm

## Articles that we need to write

- Codegen (needs more details)
- Debug info