Simple

A Simple showcase for the Sea-of-Nodes compiler IR

This repo is intended to demonstrate the Sea-of-Nodes compiler IR.

The Sea-of-Nodes is the core IR inside of HotSpot's C2 compiler and Google's V8 compiler and Sun/Oracle's Graal compiler.

Since we are show casing the SoN IR, the language being implemented is less important.
We're using a very simple language similar to C or Java, but with far fewer features. The Sea-of-Nodes is used for machine code generation in these industrial strength systems - but for this demonstration the backend is both difficult and less important.

This repo also is not intended to be a complete language in any sense, and so the backend will probably start with levering C or Java.

Chapters

The following is a rough plan, subject to change.

Each chapter will be self-sufficient and complete; in the sense that each chapter will fully implement a subset of the simple language, and include everything that was created in the previous chapter. Each chapter will also include a detailed commentary on relevant aspects of the Sea Of Nodes intermediate representation.

The simple language will be a small subset of C.

• Chapter 1: Script that returns an integer literal, i.e., an empty function that takes no arguments and returns a single integer value. The return statement.
• Chapter 2: Simple binary arithmetic such as addition, subtraction, multiplication, division with constants. Peephole optimization / simple constant folding.
• Chapter 3: Local variables, and assignment statements. Read on RHS, SSA, more peephole optimization if local is a constant.
• Chapter 4: A non-constant external variable input named arg. Binary and Comparison operators involving constants and arg. Non-zero values will be truthy. Peephole optimizations involving algebraic simplifications.
• Chapter 5: if statement. CFG construction.
• Chapter 6: Peephole optimization around dead control flow.
• Chapter 7: while statement. Looping construct - eager phi approach.
• Chapter 8: Looping construct continued, lazy phi creation, break and continue statements.
• Chapter 9: Global Value Numbering. Iterative peepholes to fixpoint. Worklists.
• Chapter 10: One dimensional static length array type. Array load/store.
• Chapter 11: Memory effects: general memory edges in SSA. Peephole optimization around load-after-store/store-after-store.
• Chapter 12: Functions and calls.
• Chapter 13: Boolean operators &&, || and ! including short circuit.
• Chapter 14: Equivalence class aliasing, fine grained peephole optimizations. Free ptr-to analysis in SoN; but does not handle aliasing in arrays.
• Chapter 15: Global Code Motion - unwind SoN to CFG. Scheduling.
• Chapter 16: Instruction selection, BURS.
• Chapter 17: Backend register allocation.
• Chapter 18: Garbage Collection.