⚠️ THIS PROJECT IS NO LONGER MAINTAINED ⚠️

Please use peepz80 instead

peepz80 is the next generation successor to this project and is actively supported.

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upeep80 - Universal Peephole Optimizer for 8080/Z80 (ARCHIVED)

A language-agnostic optimization library for 8080 and Z80 compilers.

Overview

upeep80 provides high-quality optimization passes for compilers targeting the Intel 8080 and Zilog Z80 processors. The library is designed to be reusable across different source languages.

Features

AST-Level Optimizations

• Constant Folding: Evaluate compile-time constant expressions
• Constant Propagation: Replace variables with their constant values
• Algebraic Simplification: x+0=x, x1=x, x0=0, etc.
• Strength Reduction: Replace expensive operations with cheaper equivalents
  • Multiply/divide by power-of-2 → shifts
  • Modulo by power-of-2 → bitwise AND
• Dead Code Elimination: Remove unreachable code
• Common Subexpression Elimination (CSE): Eliminate redundant calculations
• Copy Propagation: Track variable aliases
• Dead Store Elimination: Remove unused assignments
• Loop Optimizations:
  • Loop-invariant code motion
  • Loop unrolling (configurable)
• Boolean Simplification: x=x→true, x<>x→false
• Procedure Inlining: Inline small procedures

Peephole Optimizations

• Pattern-based optimization on Z80 assembly
• Redundant load/store elimination
• Jump optimization (including relative jumps for Z80)
• Stack operation combining
• Register allocation cleanup
• 8080 to Z80 mnemonic translation

Optimization Levels

• Level 0: No optimization
• Level 1: Basic (constant folding, algebraic simplification)
• Level 2: Standard (+ strength reduction, dead code elimination)
• Level 3: Aggressive (+ CSE, loop optimizations, inlining)

Optimization Targets

• Speed: Optimize for execution speed
• Size: Optimize for code size
• Balanced: Balance between speed and size

Installation

pip install upeep80

Or for development:

git clone https://github.com/yourusername/upeep80.git
cd upeep80
pip install -e ".[dev]"

Usage

AST Optimization

from upeep80 import ASTOptimizer, OptimizeFor

# Create optimizer
optimizer = ASTOptimizer(
    opt_level=2,
    optimize_for=OptimizeFor.BALANCED
)

# Optimize your AST
optimized_ast = optimizer.optimize(ast_tree)

# Check statistics
print(f"Constants folded: {optimizer.stats.constants_folded}")
print(f"Dead code eliminated: {optimizer.stats.dead_code_eliminated}")

Peephole Optimization

from upeep80 import PeepholeOptimizer, Target

# Create optimizer
optimizer = PeepholeOptimizer(
    target=Target.Z80,
    opt_level=2
)

# Optimize assembly code
optimized_asm = optimizer.optimize(assembly_lines)

# Check statistics
print(f"Patterns applied: {optimizer.stats.patterns_applied}")
print(f"Instructions eliminated: {optimizer.stats.instructions_eliminated}")

Architecture

upeep80 is designed to be language-agnostic:

AST Optimizer

• Works on generic expression trees
• Requires minimal AST node interface:
  • Binary/unary expressions
  • Literals (integer, real)
  • Identifiers
  • Statements (assignment, if, loop, etc.)
• Can be adapted to any language's AST

Peephole Optimizer

• Works directly on assembly text
• No knowledge of source language required
• Pattern-based transformation engine
• Configurable for 8080 or Z80 targets

Used By

• uplm80 - PL/M-80 compiler for Z80
• uada80 - Ada compiler for Z80

Examples

See the examples/ directory for complete examples:

• optimize_ast.py - AST optimization example
• optimize_asm.py - Assembly peephole optimization example
• custom_patterns.py - Custom peephole pattern definition

Documentation

Full documentation is available at docs/:

• API Reference
• Optimization Guide
• Custom Patterns
• Integration Guide

Development

Running Tests

pytest

Type Checking

mypy upeep80

Code Formatting

black upeep80
ruff check upeep80

Performance

Benchmarks on typical compiler workloads:

• AST optimization: ~10,000 nodes/second
• Peephole optimization: ~50,000 instructions/second
• Memory usage: ~100MB for typical compilation unit

Contributing

Contributions are welcome! Please see CONTRIBUTING.md for guidelines.

License

This project is licensed under the GNU General Public License v2.0 - see LICENSE for details.

History

upeep80 was extracted from the uplm80 project to provide a reusable optimization library for multiple retro compiler projects targeting the 8080/Z80 architecture.

Acknowledgments

• Optimization techniques based on classic compiler optimization literature
• Pattern-based peephole optimization inspired by Davidson & Fraser's work
• Z80 instruction set reference from z80.info

See Also

• uplm80 - PL/M-80 compiler
• uada80 - Ada compiler for Z80
• Z80 CPU User Manual