upeepz80 - Universal Peephole Optimizer for Z80

A language-agnostic peephole optimization library for Z80 compilers that generate pure Z80 assembly.

Overview

upeepz80 provides high-quality optimization passes for compilers targeting the Zilog Z80 processor. Unlike upeep80, this library expects pure Z80 mnemonics in lowercase as input (ld, jp, jr, etc.) and produces optimized Z80 assembly output with lowercase mnemonics.

If your compiler generates 8080 mnemonics (MOV, MVI, LXI, etc.) that need translation to Z80, use upeep80 instead.

Features

Peephole Optimizations

• Pattern-based optimization on Z80 assembly
• Redundant load/store elimination
• Jump optimization (jp to jr conversion, jump threading)
• djnz conversion (dec b; jr nz → djnz)
• Stack operation combining (push/pop to ld conversions)
• Dead store elimination
• Tail call optimization (call x; ret → jp x)
• Register copy optimization (push hl; pop de → ld d,h; ld e,l)

Z80-Specific Features

• Relative jump optimization (jp → jr where in range)
• djnz loop optimization
• Z80 block instruction awareness
• Direct ld de,(addr) usage (Z80-only instruction)

Installation

pip install upeepz80

Or for development:

git clone https://github.com/avwohl/upeepz80.git
cd upeepz80
pip install -e ".[dev]"

Usage

Basic Usage

from upeepz80 import optimize

# Optimize Z80 assembly code
assembly = """
    ld a,0
    or b
    push hl
    pop de
    jp LABEL
LABEL:
    ret
"""

optimized = optimize(assembly)
print(optimized)
# Output:
#     xor a          ; ld a,0 → xor a (smaller): or b sets the flags xor a changes
#     or b
#     ld d,h         ; push/pop → register moves (faster)
#     ld e,l
# LABEL:
#     ret            ; jp to next instruction eliminated

Without the or b, ld a,0 stays: xor a also sets the flags, and the caller this code returns to might read them.

For the PeepholeOptimizer class and its statistics, see docs/INTEGRATION.md.

Documentation

• docs/INTEGRATION.md: integration guide, the PeepholeOptimizer class, statistics, input format, migrating from upeep80
• docs/design.md: optimization phases, correctness, architecture, performance, comparison with upeep80, history
• docs/development.md: running the tests, type checking, code formatting, contributing
• docs/noopt.md: ;#noopt begin and ;#noopt end regions, and disable= to stop named rewrites
• CHANGELOG.md: release history

License

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

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See Also

• upeep80 - Optimizer with 8080 input support
• Z80 CPU User Manual