# tms-c-compiler

A modern C toolchain for the DEC VT1200 / TI TMS34010, built as a small fork of
upstream LLVM.

**Status: M3.** `llc -march=tms34010` emits GSPA-compatible assembly using the
TI ABI: integer/pointer arguments are pushed on the program stack, the result is
returned in `A8`, frames use `A13`/`A14`/`A15`, and functions end in `RETS 2`
(`RETS 0` without arguments). M3 adds conditional/unconditional branches,
ordinary `while`/`for` loops, integer ALU/shift operations, and the first
compiled C Xlib client: a four-call window opened with `XOpenDisplay`, created with
`XCreateSimpleWindow`, mapped with `XMapWindow` and synchronized with `XSync`.
It is still **assembly-only**: no object writer, no `clang -c`, and no native
COFF; GSPA/GSPLNK under DOSBox produce the COFF. XImage/XEvent, the real client,
structs by value, function pointers, floats and `i64` remain M4/M5.

- Design: [`docs/superpowers/specs/2026-11-10-tms34010-llvm-design.md`](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`](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`](docs/superpowers/plans/2026-11-11-tms34010-m1-minimal-backend.md)
- M2 plan: [`docs/superpowers/plans/2026-11-11-tms34010-m2-ti-abi-and-rom-calls.md`](docs/superpowers/plans/2026-11-11-tms34010-m2-ti-abi-and-rom-calls.md)
- M3 plan: [`docs/superpowers/plans/2026-11-11-tms34010-m3-control-flow-and-xlib-window.md`](docs/superpowers/plans/2026-11-11-tms34010-m3-control-flow-and-xlib-window.md)
- Spike: [`spike/REPORT-23.md`](spike/REPORT-23.md) (current, LLVM 23.1.5);
  [`spike/REPORT.md`](spike/REPORT.md) (historical, 19.1.7)

## Repositories

- **Compiler fork:** <https://git.wut.ee/opencode.siil.arti.ee/llvm-tms34010>
  (branch `m3`) — the full buildable LLVM 23.1.5 tree with the TMS34010
  target, clang bit-address changes and the M2/M3 backend. Branch `m2` (the
  repository default) is the M2 snapshot; branch `tms34010` is the M1 tip and
  keeps the original M1 backend and suite.
- **This project:** <https://git.wut.ee/opencode.siil.arti.ee/tms-c-compiler>
  (branch `m3`) — plans/specs, VT1200 integration tooling, `tms-bitaddr`,
  `tms-clang`, symbols, the M2/M3 harnesses and the spike. Branch `m2` (the
  repository default) is the M2 snapshot and branch `m1` is the reproducible M1
  snapshot, including the retired M1 harness.

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; M2/M3
do not change it.

## What M3 provides

M3 adds integer control flow and the first compiled C Xlib client, still
assembly-only:

- Conditional and unconditional branches for `i32` and pointer values:
  `CMP`/`CMPI` plus `JAEQ`/`JANE`, the signed `JALT`/`JALE`/`JAGT`/`JAGE`, the
  unsigned `JALO`/`JALS`/`JAHI`/`JAHS`, and `JAUC` for an unconditional jump.
  Ordinary `while`/`for` loops (subject to the M3 limitations below), if/else
  and `?:` work; `?:` expands to a compare plus a two-block diamond
  (`SELECTCC`), and `setcc` becomes that diamond over 1/0.
- Integer ALU and shift operations: `SUB`, `AND`, `OR`, `XOR`, `NEG`, `NOT`,
  `SLL`, `SRL`, `SRA`, plus `ADDI`/`ANDI`/`SLLK`/`SRAK`/`SRLK` immediates.
- The first compiled C Xlib window: `XOpenDisplay`, `XCreateSimpleWindow`
  (nine arguments in the ROM's order: display, root, x, y, width, height,
  border width, border, background), `XMapWindow` and `XSync`. All four go
  through validated ROM import stubs.
- The ROM's `Display`/`Screen` field displacements are **bit** offsets
  `0x480` (`Display.screens`) and `0x40` (`Screen.root`), i.e. byte offsets
  `0x90` and `0x8` in `scripts/m3/vt1200_xlib.h`.
- Misaligned accesses: `MOVE`/`MOVB` and the FS0/FS1 field-size forms have no
  alignment requirement on the TMS34010, so packed and bit-addressed struct
  fields select directly instead of being split into byte-wide accesses.
- Nine `m3-*.ll` lit tests, for a total of 46 with the M2 suite; the M3
  end-to-end, dis34, layout and differential gates (below).

M3 remains an `i32`/pointer milestone. `setcc` is supported, but narrow
(`i8`/`i16`) parameters and returns are still rejected. Branches on `i64`,
floats, aggregates, varargs and indirect calls are not supported. The backend
still emits assembly only.

### M3 limitations

- **Narrow loads are sign-extending only.** `MOVB` handles signed `char` and
  the FS0 `MOVE` handles signed `short`; `unsigned char`, `unsigned short` and
  `_Bool` loads need a zero-extending pattern that M3 does not have. They stop
  `llc` with a raw `Cannot select`, which `m3-reject-zext.ll` pins. M4 adds the
  zero-extending loads; do not assume general narrow-load support in M3.
- **`-O2` loop exit-value rewriting is not lowered.** IndVarSimplify can turn
  `sumto`'s loop into a closed-form `i33` multiply, which M3 cannot select. The
  M3 harness therefore builds `branch.c` with `-replexitval=never`. Ordinary
  `while`/`for` loops that keep a real back-edge and phi work. M4/M5 must add
  multiply/`i64` lowering, a target-level pass policy, or a target diagnostic
  instead of a raw abort.

## What M2 provides (branch `m2`)

M2 replaces the M1 test convention with the TI ABI and stops at assembly:

- `llc -march=tms34010 -filetype=asm` for straight-line `i32`/pointer
  functions with calls, frames and locals.
- A caller saves `A14` (STK) on the system stack, pushes arguments on the
  program stack **in reverse order** (each a 32-bit slot), emits `CALLA`,
  then re-establishes both field sizes (`SETF 16,0,0`, `SETF 32,0,1`).
- A callee starts with `SETF 16,0,0`/`SETF 32,0,1`, saves the used
  A0–A7/A9–A12 registers and the old FP on the system stack, sets `FP = STK`,
  allocates the frame with `ADDI`, and restores both stacks in the epilogue.
  The first explicit argument is at `FP(-32)`, the second at `FP(-64)`, and
  so on; locals live at positive FP offsets.
- `void`, `i32` and pointer returns, in `A8`; `RETS 2` when the function has
  explicit arguments, `RETS 0` otherwise.
- Initialized globals, string/byte-array literals and pointer initializers in
  `.data`; zero-initialized mutable globals stay in `.bss`. The loader copies
  `.data` along with `.text`.
- ROM import stubs generated from `symbols/vt1200-v22.syms`. M2 consumes
  `strlen` only: `_strlen: jauc 3FB458D0h`. `CALLA _strlen` pushes the return
  PC, the stub jumps to the ROM, and the ROM's `RETS 2` returns directly to
  our caller.
- Thirty-seven `llvm-lit`/FileCheck tests under
  `llvm/test/CodeGen/TMS34010/m2-*.ll`, including negative tests that pin the
  loud refusals. The ABI/data coverage includes `m2-returned`,
  `m2-returned-call`, `m2-call-noret`, `m2-data-align`, `m2-data-avail`,
  `m2-data-z64` and `m2-data-i1`.
- End-to-end MAME and dis34 gates, plus a differential check against assembly
  generated once by the 1987 TI compiler (see below).

## The TI ABI

| | M1 test convention (branch `m1`) | TI ABI (M2/M3) |
|---|---|---|
| Integer/pointer arguments | `A0`–`A3`, four maximum | program stack via `A14` (STK), pushed in reverse |
| Argument slots | registers | first at `FP(-32)`, second at `FP(-64)`, … |
| Return value | `A0` | `A8` |
| Frame | none; leaf functions only | `A13` FP, `A14` STK, `A15` system stack |
| Locals | none | positive FP offsets |
| Return instruction | `RETS 0` | `RETS 2` with arguments, `RETS 0` without |
| Calls, callee-saves, stack args | rejected | required |
| Field size | harness sets FS1/FS0 before entry | `FS0 = 16` and `FS1 = 32`, set in the prologue and after every call |

The callee-saved set is `A0`–`A7` and `A9`–`A12`; `A8` is the return register
and `A13`–`A15` are reserved. After `n` system-stack pushes the saved old STK
is at `SP + (n+1)*32`, and `RETS N` pops the return PC and advances `SP` by
`32 + 16N`. `FS0` must be 16 and `FS1` must be 32 at function entry and
immediately after every `CALLA` (`SETF 16,0,0` then `SETF 32,0,1`), because
ROM code may change either field size. FS0 drives `short` loads/stores and FS1
drives 32-bit words.

## Run the M3 gates

These are the documented commands on branch `m3`; all must pass.

```sh
# 1. Build llc, opt, clang and the test tools
ninja -C build/llvm-clean-build llc opt clang llvm-config FileCheck count not

# 2. LLVM codegen tests: 46 passed (37 m2-* + 9 m3-*)
build/llvm-clean-build/bin/llvm-lit -v \
  build/llvm-clean-build/test/CodeGen/TMS34010 --filter='(m2|m3)-'

# 3. Layout/symbols, then compile, assemble, link and run in MAME
scripts/tests/m3/run.sh
# -> layout.sh: PASS (Display.screens=0x480, Screen.root=0x40; ...)
# -> M3 MAME: PASS
#    (display/root/window nonzero, sum=55 max=22 lt=1, screens=0x480 root=0x40)

# 4. Rebuild the COFF and check the GSPA encodings with dis34
scripts/tests/m3/dis-roundtrip.sh
# -> M3 dis34 round-trip: PASS

# 5. Differential TI-compiler control-flow/Xlib check (no DOSBox)
scripts/tests/m3/diff/check.sh
# -> M3 diff: PASS

# 6. Negative controls: the same check must reject a wrong TI displacement
scripts/tests/m3/diff/negative-control.sh
# -> M3 diff negative controls: PASS

# 7. GEP scaling/normalization tool tests
tools/tms-bitaddr/tests/run.sh
# -> tms-bitaddr: PASS
```

`scripts/tests/m3/run.sh` first runs `scripts/tests/m3/layout.sh` (the ROM's
`0x480`/`0x40` bit displacements in both our asm and the 1987 golden) and
`scripts/m3/validate-syms.sh` (the four Xlib imports), then compiles
`scripts/m3/branch.c`, `layout.c` and `xhello.c` with `scripts/tms-clang -O2`,
runs `llc -march=tms34010 -O0 -filetype=asm`, generates the per-ROM import
stubs, concatenates the result with `scripts/m3/entry.asm`, assembles/links
with GSPA/GSPLNK 2.00 under DOSBox, and loads the COFF in MAME. `branch.c` is
built with `opt -replexitval=never`, because the default exit-value rewrite
turns `sumto`'s loop into an `i33` multiply that this target cannot select;
the loop itself is the point of the test.

The MAME run pins `VT1200_MONITOR=VR319` (the real 2048-bit row pitch) and
checks the ABI markers — nonzero display/root/window ids, `sumto(10) == 55`,
`max2(20, 22) == 22`, `lt(5, 7) == 1`, `layout_screens() == 0x480`,
`layout_root() == 0x40` — and, decisively, two all-white 32-bit client words in
VRAM at (150,150) and (250,200) inside the mapped window. A markers-only run or
a root-window bit is a failure. Paths are overridable with `TMS_CLANG`,
`TMS_OPT`, `TMS_BITADDR`, `TMS_LLC`, `MAME`, `DOSBOX`, `SDK_IMG`, `M3_WORK`,
`M3_COFF` and `M3_SDK`.

`scripts/tests/m3/dis-roundtrip.sh` rebuilds through the normal GSPA/GSPLNK
path and uses `dis34` to check the linked Xlib stubs (`JAUC` to the ROM bit
addresses), the nine-argument `XCreateSimpleWindow` push order, the branch code
(`CMP`, `JALT`, `JAGT`, `JAEQ`, `JAUC`, `LBB…` labels), the old-STK restore
offsets, and the `"0::0"` `.data` bytes.

`scripts/tests/m3/diff/check.sh` is the CI golden check. It compares the ABI
shape of our assembly with stored output from the 1987 TI compiler for the same
K&R sources: a conditional branch and an unconditional loop back-edge in
`sumto`, a conditional branch in `max2`, the function's last `RETS` being
`RETS 2`, nine `XCreateSimpleWindow` argument pushes, and the `0x480`/`0x40`
bit displacements. The displacements must appear in the load that uses them
(TI `*A7(1152)` and `*A7(64),*FP(32),1`; ours an `ADDI 1152`/`ADDI 64` feeding
a load through the same register), with exact token boundaries, so an
unrelated local at `*FP(64)`, the constant `0x400`, or a prefix such as
`0x4800` cannot satisfy them. `scripts/tests/m3/diff/negative-control.sh`
mutates the stored TI displacement to 512 (and to `0x4800`) and requires
`check.sh` to fail. The check does not verify the result register or argument
order: the MAME gate checks the returned values and `dis-roundtrip.sh` checks
the push order. It does not compare instruction selection byte-for-byte. The
stored `ti-branch.s` and `ti-xhello.s` were generated once with
`gspcpp`/`gspcc`/`gspcg` (GSP C Compiler 2.01) under DOSBox; CI never runs
DOSBox, it greps the stored files. As in the MAME gate, `branch.c` must be
built with `-replexitval=never`; the default exit-value rewrite turns
`sumto`'s loop into an unselectable `i33` multiply.

## Run the M2 gates (default branch)

These are the M2 commands; they also pass on `m3` (verified on branch `m3` on
2026-11-11: `M2 MAME: PASS`, `M2 dis34 round-trip: PASS`, `M2 diff: PASS`). The
M1 harness and suite are on branch `m1` and are **not** M2 gates: they encode
the retired M1 register convention.

```sh
# 1. Build llc, opt, clang and the test tools
ninja -C build/llvm-clean-build llc opt clang llvm-config FileCheck count not

# 2. LLVM codegen tests: 37 passed
build/llvm-clean-build/bin/llvm-lit -v \
  build/llvm-clean-build/test/CodeGen/TMS34010 --filter='m2-'

# 3. Compile, assemble, link and run in MAME
scripts/tests/m2/run.sh
# -> M2 MAME: PASS
#    (check=4 first=20 second=22 caller=42 locals=7 keep=16)

# 4. Rebuild the COFF and check the GSPA encodings with dis34
scripts/tests/m2/dis-roundtrip.sh
# -> M2 dis34 round-trip: PASS

# 5. Differential TI-compiler ABI check (no DOSBox)
scripts/tests/m2/diff/check.sh
# -> M2 diff: PASS

# 6. GEP scaling/normalization tool tests
tools/tms-bitaddr/tests/run.sh
# -> tms-bitaddr: PASS
```

`scripts/tests/m2/run.sh` compiles five C inputs with `scripts/tms-clang -O2`,
runs `llc -march=tms34010 -O0 -filetype=asm` on the normalized IR, generates
the per-ROM import stubs, concatenates the result with `scripts/m2/entry.asm`,
assembles/links with GSPA/GSPLNK 2.00 under DOSBox, then loads the COFF in
MAME. It checks `strlen("0::0") == 4`, two-argument order, a direct call, a
local frame, and callee-saved preservation. Paths are overridable with
`TMS_CLANG`, `TMS_OPT`, `TMS_BITADDR`, `TMS_LLC`, `MAME`, `DOSBOX`, `SDK_IMG`,
`M2_WORK`, `M2_COFF` and `M2_SDK`.

`dis-roundtrip.sh` runs the same build and disassembles the linked `.text` with
the VT1200 tree's `dis34`, checking the TI-ABI instructions at their linked bit
addresses, the old-STK restore offset against the push count, and the copied
`.data` bytes.

`scripts/tests/m2/diff/check.sh` is the CI golden check. It compares the ABI
shape of our assembly with stored output from the 1987 TI compiler for the same
K&R sources: first argument at `FP(-32)`, second at `FP(-64)`, result in `A8`,
`RETS 2` for `add2`, a nonzero frame and `RETS 0` for `locals`. It does not
compare instruction selection byte-for-byte. The stored `ti-add2.s` and
`ti-locals.s` were generated once with `gspcpp`/`gspcc`/`gspcg` (GSP C Compiler
2.01) under DOSBox; CI never runs DOSBox, it greps the stored files.

## `.data`, strings and the loader

GSPA 2.00 has no ELF sections. M2 emits raw `.data` text, never `.rodata`,
`.asciz`, `.p2align` or `.section`:

- `i8` scalar or byte/string array: `.byte` with GSPA hex (`068h`)
- `i16` scalar: `.word`
- `i32` scalar: `.long`
- pointer: `.long _symbol+<bit addend>` (the addend is already in bits)
- `.even` before a `.data` global whose alignment is at least 16 bits, so the
  label and the following `.word`/`.long` agree.

A scalar's directive must match its width, otherwise the next global's offset
is wrong. GSPA's `.even` aligns to a 16-bit boundary only, so an explicit
`align 4`/`align 8` on a `.data` object is **not** honored in M2: the target's
standalone object alignment is 2 bytes. Private/local symbol names are
sanitized to GSPA-safe names (`_HH` for non-alphanumerics). Unsupported
initializer shapes — including arrays whose element width has no GSPA
directive (`i1`, `i64`) — fail with
`M2 .data supports only integer, pointer and byte-array initializers`.
Zero-initialized mutable globals remain `.bss` and are zeroed by the loader.

## ROM imports

ROM entry points are per-ROM-revision bit addresses, kept out of the compiler
in `symbols/vt1200-v22.syms`. `scripts/m2/gen-rom-imports.sh` turns each entry
into an absolute-jump stub:

```asm
	.globl _strlen
_strlen:
	jauc 3FB458D0h
```

`JAUC` is the TMS34010 unconditional absolute jump; GSPA 2.00 rejects bare
`ja`. M2 uses only `strlen`. M3 adds the four Xlib entries
(`XOpenDisplay`, `XCreateSimpleWindow`, `XMapWindow`, `XSync`) and validates
their stubs in `scripts/m3/validate-syms.sh` and in MAME; `symbols/README.md`
records the evidence. Do not add other Xlib dependencies until they are
validated.

## M2 non-goals

M2 deliberately rejects or omits:

- **Branches/control flow:** conditional and unconditional branches, loops,
  and spill/fixup paths that need them. A branch that reaches ISel fails
  loudly; M3 owns control flow.
- **Floating point:** float/double arguments, returns and arithmetic (M5).
- **Aggregates:** structs/unions by value, `sret`, `byval`, bitfields (M4/M5).
- **Varargs:** `...` functions and calls (M5).
- **Function pointers and indirect calls** (M4).
- **Tail calls:** ordinary `tail` markers are demoted to ordinary calls;
  `musttail` is not implemented (M2 C does not emit it). Real tail calls remain
  a later milestone.
- **Narrow ABI types:** `i8`/`i16` parameters, `i64`, and narrow returns remain
  rejected. Narrow accesses inside a function are sign-extending only: `MOVB`
  for signed `char` and FS0 `MOVE` for signed `short`; zero-extending
  `unsigned char`/`unsigned short`/`_Bool` loads are M4 work.
- **Object output:** no `MCCodeEmitter`, object writer, `llc -filetype=obj`,
  `clang -c` or native COFF. GSPA assembles and GSPLNK links the asm.
- **Xlib and clients:** no X11 headers, Xlib calls or real VT1200 clients in
  M2; only the `strlen` ROM call.

The optimizer's `returned` argument attribute is accepted because it does not
affect the stack-slot ABI; `sret`/`byval`/`inreg`/`nest` remain rejected.

## M3 non-goals

M3 deliberately stops at the first window and ordinary integer control flow:

- **XImage/XEvent and the real client:** no image transfer, event handling,
  full X11R4 headers or real VT1200 client (M4). M3 uses exactly the four Xlib
  calls above and no other Xlib entry.
- **Aggregates by value:** structs/unions passed or returned by value, `sret`,
  `byval`, bitfields (M4/M5). Struct *fields* through pointers are supported.
- **Function pointers and indirect calls:** the callee must be a direct global
  symbol (M4).
- **Floating point and `i64`:** no float/double or 64-bit integer arguments,
  returns, arithmetic or branches (M5).
- **Object output:** still no `MCCodeEmitter`, object writer,
  `llc -filetype=obj`, `clang -c` or native COFF; GSPA/GSPLNK produce the COFF.
  The `JR`/branch-relaxation code-size pass is M5 as well.
- **Varargs, `musttail`, narrow ABI parameters/returns:** unchanged from M2.

## M4 prerequisites (carry-forwards)

The final M3 review left these concrete prerequisites for M4:

- **Add zero-extending narrow loads.** M3 rejects `unsigned char`,
  `unsigned short` and `_Bool` loads (pinned by `m3-reject-zext.ll`); M4 must
  add the `ZEXTLOAD i8`/`i16` patterns and replace the reject test.
- **Namespace every private label.** `scripts/tests/m3/run.sh` prefixes
  `LBB<n>_<m>` per translation unit, but deterministic private string labels
  are not renamed. Two TUs with literals therefore collide in GSPA's flat
  symbol table. M4 must namespace all private labels or make compiler private
  names module-unique.
- **Add unsigned/`<=` runtime coverage.** `JALE`, `JALO`, `JAHI` and `JALS`,
  `JAHS`, `JANE`, `JAGE` are covered by lit tests only and do not appear in the
  compiled M3 image. M4 should add an unsigned/`<=` runtime marker.
- **Replace fragile test plumbing.** The `always_inline` root helper and the
  register-hardcoded nine-argument dis34 check are test-strength aids that will
  not survive real M4 code; make them operand- and register-independent.
- **Tighten test strength.** `m3-cmpi`'s `CHECK-DAG` for 0/1 does not pin their
  order, and `layout.sh` pairs the root probe with fixed constants; neither
  weakens the current pass, but both should be tightened.

## Repository layout

```text
build/llvm-clean/        compiler fork checkout used for M2/M3 (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/m2/              M2 harness: C inputs, entry.asm, link.cmd, stubs, checks
scripts/m3/              M3 harness: branch/xhello/layout inputs, Xlib header, entry/link
scripts/tests/m2/        M2 gates (run.sh, dis-roundtrip.sh)
scripts/tests/m2/diff/   TI golden asm and the differential ABI check
scripts/tests/m3/        M3 gates (run.sh, dis-roundtrip.sh, layout.sh)
scripts/tests/m3/diff/   TI branch/Xlib goldens, differential check + negative controls
scripts/m1/              M1 harness (historical; also on branch `m1`, not an M2 gate)
scripts/tests/m1/        M1 gates (historical; also on branch `m1`, not an M2 gate)
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 M2/M3 MAME
and dis34 gates additionally need `dosbox`, `mtools` (`mcopy`), the VT1200 SDK
image, the `dwt` COFF loader, `dis34`, and a built MAME `vt1200` binary
(`build/mame-src/vt1200`). The differential golden check needs no
DOSBox/MAME/SDK; it needs only the built `clang`, `opt`, `llc` and
`tools/tms-bitaddr/tms-bitaddr`. On Debian:

```sh
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:

```sh
./scripts/fetch-vt1200.sh          # -> vendor/vt1200, pinned 17dfd24...
```

## Build the compiler

### Compiler fork (M3, the normal path)

The fork checkout already exists at `build/llvm-clean` on `m3`. Build it in
place:

```sh
LLVM_SRC=$PWD/build/llvm-clean LLVM_BRANCH=m3 ./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:

```sh
LLVM_REPO=gitea@git.wut.ee:opencode.siil.arti.ee/llvm-tms34010.git \
LLVM_BRANCH=m3 ./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)

```sh
./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 M2/M3 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/M2/M3.

## Build the M0 support tools

The M2/M3 pipeline uses `tms-bitaddr` and `tms-clang`:

```sh
LLVM_CONFIG=$PWD/build/llvm-clean-build/bin/llvm-config \
  tools/tms-bitaddr/build.sh
```

M0 regression test (optional in M2/M3):

```sh
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
```

## Emit assembly by hand

```sh
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/add2.ll scripts/tests/m2/diff/ti-add2.c

build/llvm-clean-build/bin/llc -march=tms34010 -O0 -filetype=asm \
  /tmp/add2.ll -o /tmp/add2.s
```

The resulting function loads its arguments at `FP(-32)` and `FP(-64)`, returns
in `A8`, and ends in `RETS 2`. 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 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.

## Later milestones

M4 adds the real Xlib client (`XImage`/`XEvent`, the full X11R4 headers),
structs by value and function pointers. M5 adds the native COFF path, floats,
varargs, bitfields, `long long` and the `JR`/branch-relaxation code-size pass;
2ine r5.01 is a later speed-up for the GSPA/GSPLNK step.