tms-c-compiler
A modern C toolchain for the DEC VT1200 / TI TMS34010, built as a small fork of upstream LLVM.
Status: M1. llc -march=tms34010 emits GSPA-compatible assembly for a
small set of leaf functions, and that assembly assembles, links and runs in
MAME. M1 is an assembly-only, test-only snapshot: it uses an A0–A3/A0
register convention, not the TI ABI, and has no object writer, calls or runtime.
- Design:
docs/superpowers/specs/2026-11-10-tms34010-llvm-design.md - M0 plan:
docs/superpowers/plans/2026-11-10-tms34010-m0-fork-and-bit-address-semantics.md - M1 plan:
docs/superpowers/plans/2026-11-11-tms34010-m1-minimal-backend.md - Spike:
spike/REPORT-23.md(current, LLVM 23.1.5);spike/REPORT.md(historical, 19.1.7)
Repositories
- Compiler fork: https://git.wut.ee/opencode.siil.arti.ee/llvm-tms34010
(branch
tms34010) — the full buildable LLVM 23.1.5 tree with the TMS34010 target, clang bit-address changes and the M1 backend. - This project: https://git.wut.ee/opencode.siil.arti.ee/tms-c-compiler
— plans/specs, VT1200 integration tooling,
tms-bitaddr,tms-clang, symbols, the M1 harness and the spike.
The compiler fork is the canonical source for all target code. patches/llvm
here is a frozen M0 mirror used by the default upstream+patches build; M1
does not change it.
What M1 provides
M1 fills in the M0 target skeleton and stops at assembly:
llc -march=tms34010 -filetype=asmfor leaf 32-bit functions: integer/pointer arguments inA0–A3, result inA0, return viaRETS 0.ADDfori32,MOVIfor constants,MOVE ..., 1(FS1) for 32-bit load/store,MOVE ..., 0(FS0) fori16, and sign-extendingMOVBfori8load/store.- Constant global addresses as
MOVI _sym+bits; a surviving GEP offset is a bit offset (ADDI 24, notADDI 192). - Hard errors, not silent fallbacks, for calls (
M1 has no calls; M2 adds the TI ABI), stack frames (M1 has no stack frame), more than four register arguments, unsupported signatures (varargs,i64/float/aggregate parameters,sret/byval/inreg/nest/returned), unsupported return types, and initialized globals or string literals. - Seventeen
llvm-lit/FileCheck tests underllvm/test/CodeGen/TMS34010/m1-*.llin the compiler fork, including negative tests that pin the loud refusals. - An end-to-end path:
scripts/tms-clangIR →llc -O0 -filetype=asm→ 1987 GSPA/GSPLNK 2.00 under DOSBox → COFF → the VT1200 loader in MAME. The run checksadd(20, 22) == 42,load(&word) == 0x12345678,second() == &arr[1](asymbol+32bit relocation),loadbof a byte0x81returns the sign-extended0xFFFFFF81, andstorebleaves0x81in memory. - A
dis34round-trip that reads the linked.textfrom the COFF and checks the instructions GSPA encoded at their linked bit addresses.
M1 is not the TI ABI
| M1 test convention | TI ABI (M2) | |
|---|---|---|
| Integer/pointer arguments | A0–A3, four maximum |
program stack (via A14 STK) |
| Return value | A0 |
A8 |
| Frame | none; leaf functions only | A13 FP, A14 STK, A15 system stack |
| Return instruction | RETS 0 |
RETS 2 |
| Calls, callee-saves, stack args | rejected | required |
| Field select | harness sets FS1/FS0 before the leaf | FS1 = 32 preserved across calls |
M1 assembly is not ABI-compatible with TI's compiler or the ROM Xlib. M2 replaces the convention; do not build on the M1 register assignment.
Repository layout
build/llvm-clean/ compiler fork checkout used for M1 (ignored)
build/llvm-clean-build/ its Ninja build tree (ignored)
build/llvm-src/ M0 working fork (ignored)
patches/llvm/ frozen M0 patch series against llvmorg-23.1.5
tools/tms-bitaddr/ GEP scale/normalize tool
scripts/tms-clang IR pipeline wrapper (clang + tms-bitaddr + opt)
scripts/m1/ M1 harness: C inputs, entry.asm, link.cmd, checks
scripts/tests/m1/ M1 gates (run.sh, dis-roundtrip.sh)
scripts/tests/m0/ M0 integration tests
scripts/build-llvm.sh fork or upstream+patches build
scripts/fetch-vt1200.sh fetch the VT1200 RE tree at its pinned commit
spike/ measurement corpus and reports
symbols/ per-ROM import tables (v2.2 subset)
vendor/ fetched assets and LLVM sources (ignored)
docs/ design and plans
Prerequisites
cmake, ninja-build, ccache, a C++17 host compiler (GCC 14 is used here),
Python 3, and about 20 GB of disk for the LLVM source and build. The M1 gates
additionally need dosbox, mtools (mcopy), the VT1200 SDK image, the
dwt COFF loader, and a built MAME vt1200 binary
(build/mame-src/vt1200). On Debian:
sudo apt-get install -y cmake ninja-build ccache dosbox mtools
Fetch the VT1200 assets
The compiler contract is checked against the VT1200 tree (TI hello.s, the
Xlib call sequence, as34, dis34, SDKs, manuals). It is not vendored:
./scripts/fetch-vt1200.sh # -> vendor/vt1200, pinned 17dfd24...
Build the compiler
Compiler fork (M1, the normal path)
The fork checkout already exists at build/llvm-clean on tms34010. Build it
in place:
LLVM_SRC=$PWD/build/llvm-clean LLVM_BRANCH=tms34010 ./scripts/build-llvm.sh
# binaries: build/llvm-clean-build/bin/{llc,clang,opt,llvm-config,FileCheck}
# lit driver: build/llvm-clean-build/bin/llvm-lit
To clone the fork first instead of using an existing checkout:
LLVM_REPO=gitea@git.wut.ee:opencode.siil.arti.ee/llvm-tms34010.git \
LLVM_BRANCH=tms34010 ./scripts/build-llvm.sh
Fork mode never checks out, resets, cleans or patches the source tree; it
only runs CMake and Ninja. Local commits on the branch are safe. Use
LLVM_BUILD=... to keep a separate build directory. It builds llc, clang,
opt, llvm-config, FileCheck and the test helpers with X86 (host) and
TMS34010; a first build takes roughly 20–40 minutes.
Upstream + patches (frozen M0 path)
./scripts/build-llvm.sh
This mode clones llvmorg-23.1.5, applies patches/llvm/*.patch, and builds
build/llvm-clean-build. It owns and resets only a plain llvm-project clone:
if build/llvm-clean has some other origin (for example the M1 fork), it
refuses rather than destroying it. Use fork mode for that checkout.
scripts/export-patches.sh regenerates the committed M0 patch series with
git diff (including new files via git add -N); it is not used for M1.
Build the M0 support tools
The M1 pipeline still uses tms-bitaddr and tms-clang:
LLVM_CONFIG=$PWD/build/llvm-clean-build/bin/llvm-config \
tools/tms-bitaddr/build.sh
M0 regression test (optional in M1):
TMS_CLANG=$PWD/build/llvm-clean-build/bin/clang \
TMS_OPT=$PWD/build/llvm-clean-build/bin/opt \
TMS_BITADDR=$PWD/tools/tms-bitaddr/tms-bitaddr \
./scripts/tests/m0/run.sh
# -> M0 pipeline: PASS
Run the M1 gates
These are the documented commands; all three must pass:
# 1. LLVM codegen tests: 17 passed
build/llvm-clean-build/bin/llvm-lit -v \
build/llvm-clean-build/test/CodeGen/TMS34010 --filter='m1-'
# 2. Compile, assemble, link and run in MAME
./scripts/tests/m1/run.sh
# -> M1 MAME: PASS
# 3. Rebuild the COFF and check the GSPA encodings with dis34
./scripts/tests/m1/dis-roundtrip.sh
# -> M1 dis34 round-trip: PASS
run.sh compiles five C inputs with scripts/tms-clang -O2, runs
llc -march=tms34010 -O0 -filetype=asm on the normalized IR, concatenates
the result with scripts/m1/entry.asm and scripts/m1/char-test.asm,
assembles/links with GSPA/GSPLNK 2.00 under DOSBox, then loads the COFF in
MAME. dis-roundtrip.sh runs the same build and then disassembles the linked
.text at the symbol addresses from the COFF symbol table. Paths are
overridable with TMS_CLANG, TMS_OPT, TMS_BITADDR, TMS_LLC, MAME,
DOSBOX, SDK_IMG, M1_WORK, M1_COFF and M1_SDK.
Emit assembly by hand
TMS_CLANG=$PWD/build/llvm-clean-build/bin/clang \
TMS_OPT=$PWD/build/llvm-clean-build/bin/opt \
TMS_BITADDR=$PWD/tools/tms-bitaddr/tms-bitaddr \
scripts/tms-clang -O2 -o /tmp/add.ll scripts/m1/add.c
build/llvm-clean-build/bin/llc -march=tms34010 -O0 -filetype=asm \
/tmp/add.ll -o /tmp/add.s
Always produce the IR with scripts/tms-clang (or run tms-bitaddr --scale)
before llc: raw clang IR carries byte GEP offsets, but llc treats every
surviving GEP offset as a bit offset, so addresses would be 8× too small.
Run llc -O0 on the normalized IR that tms-clang already optimized and
scaled. tms-bitaddr --normalize consumes that scaled IR and now rejects a
typed (non-i8) or vector GEP instead of emitting its byte offset as bits.
The lit tests use llc -march=tms34010 -O2 -filetype=asm on hand-written IR
to exercise the selector pipeline directly. Output is assembly only: llc
cannot emit an object file or a usable COFF for this target.
Not yet supported (M2 and later)
- Data: only zero-initialized mutable globals (
.bss) are supported. Initialized globals, string literals and constant/private data (.data,.rodata) makellcfail loudly; the.datainitializer probe moves to M2. - Object emission: no
MCCodeEmitter, object writer,llc -filetype=obj,clang -c, or native COFF. GSPA assembles and GSPLNK links; the existing COFF loader loads. - TI ABI:
A8return,A13/A14/A15dual stack,RETS 2,FS1 = 32across calls, callee-saves, stack arguments, more than four arguments. - C features: calls, locals/
alloca, structures/byval, floats, varargs, bitfields, 64-bit arithmetic,memcpy/allocalowering. - Runtime and clients: ROM/Xlib imports,
strlen/malloc, X11 headers, real VT1200 clients, debug info. - 2ine: M1 uses the proven 1987 GSPA/GSPLNK under DOSBox, not the external 2ine r5.01 tools; 2ine is an M2 speed-up.
These are M2–M5 in the design spec, each with its own plan.