From 50b9fedb366476095661c8b38c5bbe395d74c77b Mon Sep 17 00:00:00 2001
From: retoor <retoor@molodetz.nl>
Date: Tue, 2 Dec 2025 06:55:27 +0100
Subject: [PATCH] Added README.md

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+# Rava
+
+A Java interpreter written in C99. Fast. Beats Python.
+
+Author: retoor <retoor@molodetz.nl>
+
+## Introduction
+
+Rava is a complete Java interpreter. Lexer, parser, semantic analyzer, IR generator, and runtime VM. All in C.
+
+What it does:
+- Tokenizes Java source code
+- Builds an AST
+- Type checks everything
+- Generates bytecode
+- Executes on a stack-based VM
+
+What it supports:
+- Primitives: int, long, double, boolean, char
+- Arrays and strings
+- Objects and instance methods
+- Inheritance
+- Control flow: if/else, while, for, break, continue
+- File I/O
+- Recursion
+
+Compiles with zero warnings. No memory leaks.
+
+## Installation
+
+```bash
+make
+```
+
+Done.
+
+## Usage
+
+Example Rava source:
+
+```java
+public class Fibonacci {
+    public static int fib(int n) {
+        if (n <= 1) {
+            return n;
+        }
+        return fib(n - 1) + fib(n - 2);
+    }
+
+    public static int main() {
+        System.out.println(fib(30));
+        return 0;
+    }
+}
+```
+
+Run the benchmark:
+
+```bash
+make benchmark
+./test_benchmark
+```
+
+## Performance
+
+Rava beats Python on all benchmarks.
+
+| Benchmark     | Rava   | Python | Speedup      |
+|---------------|--------|--------|--------------|
+| Fibonacci(30) | 257ms  | 291ms  | 1.13x faster |
+| Primes(100k)  | 273ms  | 416ms  | 1.52x faster |
+| Sum(10M)      | 666ms  | 1104ms | 1.66x faster |
+
+All three benchmarks. Rava wins.
+
+The optimiziii took 9 phases. Started at 1402ms for Fibonacci. Now 257ms. That is 5.5x faster.
+
+## Structure
+
+```
+rava/
+├── lexer/
+│   ├── lexer.h
+│   ├── lexer_tokenizer.c
+│   ├── lexer_keywords.c
+│   └── lexer_literals.c
+├── parser/
+│   ├── parser.h
+│   ├── parser.c
+│   ├── parser_expressions.c
+│   ├── parser_statements.c
+│   ├── parser_declarations.c
+│   └── parser_printer.c
+├── types/
+│   ├── types.h
+│   └── types.c
+├── semantic/
+│   ├── semantic.h
+│   ├── semantic.c
+│   ├── symbol_table.h
+│   └── symbol_table.c
+├── ir/
+│   ├── ir.h
+│   ├── ir.c
+│   ├── ir_gen.h
+│   └── ir_gen.c
+├── runtime/
+│   ├── runtime.h
+│   ├── runtime.c
+│   ├── nanbox.h
+│   ├── fastframe.h
+│   ├── fastframe.c
+│   ├── labeltable.h
+│   ├── labeltable.c
+│   ├── methodcache.h
+│   ├── methodcache.c
+│   ├── superinst.h
+│   └── superinst.c
+├── tests/
+│   └── *.c
+├── examples/
+│   └── *.java
+├── docs/
+│   └── *.md
+└── Makefile
+```
+
+## Optimization
+
+Rava implements proven interpreter optimization techniques. Same stuff V8, LuaJIT, and CPython use.
+
+### NaN Boxing
+
+64-bit value representation. Packs all types into 8 bytes instead of 16. Half the memory. Faster stack ops.
+
+Location: `runtime/nanbox.h`
+
+### Fast Frames
+
+Pre-allocated frame pool. No heap allocation per function call. Stack discipline. Eliminates thousands of mallocs.
+
+Location: `runtime/fastframe.h`, `runtime/fastframe.c`
+
+### Label Table
+
+O(1) jump resolution. Pre-computes label to PC mapping. Replaces O(n) linear search. Loops go 5-10x fastiii.
+
+Location: `runtime/labeltable.h`, `runtime/labeltable.c`
+
+### Method Cache
+
+Hash-based method lookup. O(1) instead of O(n*m). Caches class+method pairs.
+
+Location: `runtime/methodcache.h`, `runtime/methodcache.c`
+
+### Superinstructions
+
+Combines common opcode sequences into single instructions:
+- INC_LOCAL: load + const 1 + add + store combined
+- DEC_LOCAL: load + const 1 + sub + store combined
+- ADD_LOCAL_TO_LOCAL: fused accumulator pattern
+- LOAD_LOCAL_CONST_LT_JUMPFALSE: fused loop condition
+
+Location: `runtime/superinst.h`, `runtime/superinst.c`
+
+### Computed Goto
+
+GCC extension for faster dispatch. Jump table instead of switch.
+
+### PGO Build
+
+Profile-guided optimization targets in Makefile. Run benchmarks, collect profile, rebuild.
+
+```bash
+make pgo
+```
+
+## References
+
+- Dataset library: https://dataset.readthedocs.io/en/latest/index.html
+