6502 C compilers benchmark

Easing the way to compare code generated by cc65, 6502-gcc, vbcc, and KickC.

This repository contains scripts to:

• Compile the same source with various 6502 compilers,
• Show the code generated,
• Emulate generated binaries,
• Show performance information.

Running benchs

Setuping your environement

Dependencies

You will need an up and running installation of:

• cc65: mandatory, benchmarks for all compilers use CA65 assembler
• Python: highly recomended, automation scripts are written in Python
• gcc or clang: to build the emulator that run banchmarks

If you want to benchmark extra emulators, you will need them ready to compile some source:

• 6502-gcc: clone and compile it from there: https://github.com/itszor/gcc-6502-bits
• vbcc

Build the emulator

The emulator is necessary to run benchmarks. It is not a NES/C64/AppleII/... emulator, it has its own expectations about memory layout.

$ cd emulator/
$ g++ -Imos6502 emulator.cpp mos6502/mos6502.cpp -o emulator

You should now have an executable named emulator in the emulator/ folder.

Setting your environment variables

Automation scripts heavily rely on environment variables to find compilers.

Note: you can skip any *_BIN if you have the binary in your PATH

Always needed:

$ export CA65_BIN=/somewhere/cc65/bin/ca65
$ export LD65_BIN=/somewhere/cc65/bin/ld65

Needed for benching cc65:

$ export C65_BIN=/somewhere/cc65/bin/cc65
$ export CC65_LIB=/somewhere/cc65/lib

Needed for benching vbcc:

$ export VBCC=/somewhere/vbcc6502/vbcc6502_linux/vbcc
$ export VBCC_BIN=/somewhere/vbcc6502/vbcc6502_linux/vbcc/bin/vc

Needed for benching 6502-gcc:

$ export GCC6502_BIN=/somewhere/gcc-6502-bits/prefix/bin/6502-gcc

Needed for benching KickC:

$ export KICKC_BIN=/somewhere/kickc/bin/kickc.sh

Running a benchmark

Running the unzip bench with cc65:

compilers/cc65/bench code_samples/unzip/unzip.c code_samples/unzip/unzip_data.s

This will produce a fat json on standard output. It contains:

• The number of cycles taken by the generated code
• The size of the generated code
• The memory dump after execution
• The generated assembler

You may add --options="-Oirs" to pass these flags to the compiler.

You may add --verbose to have compiler commands being print before executing them.

All compilers/*/bench scripts share the same comand line interface. Feel free to run the same test with different compilers.

Impacting environment variables

• CA65_BIN: path to ca65 binary (default: ca65 [aka search in PATH])
• CC65_BIN: path to cc65 binary (default: cc65 [aka search in PATH])
• LD65_BIN: path to ld65 binary (default: ld65 [aka search in PATH])
• CC65_LIB: path where cc65's standard *.lib can be found (default: tries to link without --lib-path, doomed to fail)
• GCC6502_BIN: path to 6502-gcc binary (default: 6502-gcc [aka search in PATH])
• VBCC_BIN: vc binary from VBCC toolchain (default: vc [aka search in PATH])
• VBCC: shall point to VBCC's root dir for vbcc compilation to work
• KICKC_BIN: path to kickc.sh (or equivalent for your platform) (default: kickc.sh [aka search in PATH])
• EMU65: path to the emulator compiled from the emulator/ dir