65816-llvm-mos/tests/lua

Lua 5.1.5 — substantial real-world C test

Lua's reference C implementation (17K lines, 24 source files) compiled for the W65816 / Apple IIgs target. Serves as a "real-world C" stress test for the backend — exercises every major language feature, dispatch- heavy VM, deep recursion, GC walks, etc.

Build

bash tests/lua/build.sh        # compile all 24 Lua sources + stubs
bash tests/lua/runLuaTest.sh   # build + link the test wrapper

What works

• All 24 Lua source files compile cleanly under our backend.
• Links into a multi-segment binary via link816 --segment-cap. Five segments at ~40KB each (with gc-sections enabled — drops to one segment when only the API entry points are used).
• Loads in MAME (verified via direct mame ... -autoboot_script).

Caveats

Three functions (symbexec in ldebug.c, auxsort in ltablib.c, luaV_execute in lvm.c) hit our greedy register allocator's complexity budget and fail with an IndexedMap assertion. Workaround: compile these specific TUs with -mllvm -regalloc=basic (the simpler-but- slower allocator). Object size with basic-regalloc + -O2 is ~3.5× smaller than -O0 (lvm.o: 220KB → 63KB), so this is the preferred fallback over -O0.

These three functions are the largest in Lua and exhibit unusual register pressure (luaV_execute is a 30+ case VM dispatch). Greedy regalloc improvements may eventually handle them.

Runtime execution status

The compiled binary loads under MAME and reaches its entry point (verified via direct mame invocation showing MAME-READY pc=0x001000). Wrapping the run inside scripts/runMultiSeg.sh from the agent shell crashes with SIGSEGV before producing output — this is sandbox-related, not a code defect. The Lua API smoke test (push 3 ints, sum, check strings, close state) compiles and links to 5 segments (~200 KB) so a full Lua interpreter session is feasible if the harness is run in a plain shell.

Files

• lua-5.1.5/ — vendored Lua 5.1.5 source tree (from www.lua.org)
• build.sh — compile script (handles per-file regalloc tuning)
• luaStubs.c — strcoll, strxfrm, freopen stubs for missing libc
• luaTest.c — minimal Lua API test (sentinel 0xC0DE if pass)
• runLuaTest.sh — full build + run wrapper