Freestanding `thumbv8m.main-none-eabi`

Generic Cortex-M33 freestanding target support in Inauguration.

Status

Piece	Status
Target registry identity	Implemented
Native-emit registry	Implemented (`elf32-relocatable-object+raw+uf2`)
Core IR → Thumb-2 lower	Implemented (`native_emit::thumb_lower`)
Thumb-2 encoder	Implemented (`native_emit::thumb`)
ELF32 relocatable object	Implemented (real lowered bodies)
Raw binary helper	Existing `native_emit::raw`
UF2 packing helper	Implemented (`native_emit::uf2`)
Linker layout script generator	Implemented (`native_emit::linker_layout`)
Vector table / IRQ synthesis	Product-owned (e.g. Subspace)
MPU / board capsules	Product-owned

Owned scalar subset

Int/Bool params (AAPCS r0–r3) and locals
return, let, assign, expr statements
if / else, while
arithmetic + - * & | ^, unary - / !
compares == != < <= > >=
direct same-module calls (bl)
extern <lang> fn bindings (extern zig fn ... etc.) emitting R_ARM_THM_CALL relocations for static-linking against C/Rust/Zig/Go/V objects
MMIO memory ops: load8 / load16 / load32 / load64, store8 / store16 / store32 / store64 (plain ldrb/ldrh/ldr/strb/strh/str; treated as volatile at the IR call boundary)

Supported: structs, fixed-size array locals with index/load/store, >4 params (AAPCS stack args), short-circuit &&/||, break. Rejected for now: strings, floats, closures, heap, array type annotations with explicit length. load64 / store64 touch the low 32-bit word only (freestanding Int is machine word).

ABI contract (MVP)

freestanding, no libc, no heap
AAPCS: r0 return, r0–r3 args, r4–r7/lr saved in prologue
entry symbol name supplied by caller (--entry)
ELF machine EM_ARM (40), class ELF32, little-endian
Thumb-2 instruction stream (T16/T32)

Foreign application bodies (C/Zig) must still pass product-level freestanding contract checks (stack, alloc=none/pool, blocking bounds). Inauguration only emits the object/raw/UF2 bytes once those contracts are verified upstream.

Example

in compile \
  --path answer.in \
  --target native \
  --target-triple thumbv8m.main-none-eabi \
  --linkage static-lib \
  --entry answer \
  --out answer.o \
  --json

Ownership