tinycc

tinycc

Fabrice Bellard's TCC vendored as a cross-platform exerciser for badc: multi-TU compile + link of the tcc-the-binary sources against badc's supported targets (x86_64 + aarch64 across ELF / Mach-O / PE), followed by a self-host fixed point once every TU compiles.

Source is pinned at the upstream mob branch HEAD (2026-10-16, e23dabe). The last release tag (release_0_9_27, 2017) predates years of PE / AArch64 / Mach-O fixes that the cross-platform self-host requires, so the bringup follows mob the same way distros do. Pulled through the badc vendor-deps mirror -- see setup.py.

Vendored surface

A multi-TU build of tcc-the-binary against the targets badc supports. Backends and output formats outside that scope are dropped:

• Core (every host) -- tcc.c, libtcc.c, tccpp.c, tccgen.c, tccelf.c, tccasm.c, tccdbg.c, tccrun.c, tcctools.c.
• Backend (x86_64 host) -- x86_64-gen.c, x86_64-link.c, i386-asm.c (the inline-assembly path TCC_TARGET_X86_64 still routes through).
• Backend (aarch64 host) -- arm64-gen.c, arm64-link.c, arm64-asm.c.
• Output format -- tccpe.c (Windows), tccmacho.c (macOS); ELF is the default and is handled by tccelf.c.
• Headers -- tcc.h, libtcc.h, the *-tok.h / *-asm.h token tables, and upstream's internal copies of elf.h, coff.h, dwarf.h, stab.h, stab.def.

Dropped: i386-gen.c / i386-link.c (32-bit x86 -- not a badc target), arm-*.c (32-bit ARM -- not a badc target), riscv64-*.c, c67-*.c / tcccoff.c (TI C67), il-*.c (orphaned IL backend). ONE_SOURCE is not defined, so each .c is its own TU, which is the shape that exercises badc's cross-TU linker.

include/ carries tinycc's shipped system headers (float.h, stdarg.h, stdatomic.h, tccdefs.h, ...). They are not needed to compile tcc-the-binary; they are the headers tcc exposes to programs it later compiles, and the self-host stage points the produced tcc at them.

Bringup status

Every TU in the vendored set compiles cleanly through badc on every host profile (Linux x86_64 / aarch64, macOS aarch64, Windows x86_64 / arm64). The smoke harness is gated; a TU regression fails CI.

The self-host fixed point is exercised by self_host.py, which runs five tiers in sequence on every lane:

Tier	What it asserts
samples	per-TU -c parity (badc-built tcc vs host-cc-built tcc) on 25 small fixtures
corpus	per-TU -c parity on tinycc's own 11-12 TUs
bootstrap	tcc-gen2 (host-linked from stage1-compiled TUs) compiles every TU byte-identical
gen2-self	tcc-gen2-self (stage1-self-linked) compiles every TU byte-identical to gen2's output
functional	hello-world compile + link + run round trip through stage1 and gen2

Current per-lane state:

Lane	samples	corpus	bootstrap	gen2-self	functional	notes
macOS aarch64	25/25	12/12	12/12	12/12	2/2	full fixed point
Linux x86_64	25/25	11/11	11/11	11/11	2/2	full fixed point
Linux aarch64	25/25	11/11	11/11	11/11	2/2	full fixed point
Windows x86_64	25/25	12/12	12/12	12/12	2/2	full fixed point
Windows arm64	25/25	12/12	12/12	12/12	2/2	full fixed point

All five tiers are strict-gated on every lane.

Already-closed gaps that the bringup surfaced:

• <inttypes.h> PRI / SCN format macros over <stdint.h>.
• __attribute__ / __declspec absorbed as empty fn macros.
• <unistd.h> exposes ssize_t / size_t / off_t / pid_t / uid_t / gid_t per POSIX-2017 through <sys/types.h>.
• <setjmp.h> ships per-platform libc::setjmp / libc::longjmp bindings; on Windows x86_64 the header wraps setjmp / longjmp in alignment macros so msvcrt's _setjmp sees a 16-byte-aligned env (the movdqa saves of xmm6..xmm15 fault otherwise).
• sizeof(typedef T arr[N]) reports N * sizeof(T) per C99 6.5.3.4 / 6.7.7 (the typedef array dim is propagated through the operand-shape parser).
• Integer literal u / l / L suffixes drive longness + unsignedness per C99 6.4.4.1.
• Unary - on uint64_t preserves the operand's width per C99 6.5.3.3p3.
• Bitfield storage unit follows the base type per C99 6.7.2.1p11 (the unit width tracks sizeof(base_type), not a hard-coded 8 bytes).
• Bitwise & / ^ / | result type follows the usual arithmetic conversions per C99 6.5.10 / 6.5.11 / 6.5.12; a downstream arithmetic op does not narrow a 64-bit operand through a sign-extend from bit 31.

config.h

Upstream's ./configure writes a config.h that picks the target, output format, and search paths. The smoke harness synthesizes a minimal config.h per host instead -- it does not invoke configure -- selecting macros from this table:

Host	Target macros
Linux x86_64	TCC_TARGET_X86_64
Linux aarch64	TCC_TARGET_ARM64
macOS aarch64	TCC_TARGET_ARM64, TCC_TARGET_MACHO
Windows x86_64	TCC_TARGET_X86_64, TCC_TARGET_PE
Windows aarch64	TCC_TARGET_ARM64, TCC_TARGET_PE

CONFIG_TCC_SYSINCLUDEPATHS / CONFIG_TCC_LIBPATHS are baked in per host so the produced tcc resolves <stdio.h> etc. and -lkernel32 / -lmsvcrt etc. without a separate install step:

Host	CONFIG_TCC_SYSINCLUDEPATHS (after {B} resolves to demos/tinycc)	CONFIG_TCC_LIBPATHS
Linux	{B}/include:/usr/include/<triplet>:/usr/include	{B}:/usr/lib/<triplet>:/usr/lib
macOS	{B}/include:<SDK>/usr/include:/usr/include	{B}:<SDK>/usr/lib:/usr/lib
Windows	{B}/win32/include;{B}/win32/include/winapi;{B}/include	{B}/lib;{B}/win32/lib

CONFIG_TCC_ELFINTERP stays undefined; the self-host stage supplies it via CLI when it links an ELF binary that needs one.

The synthesized config.h also forces CONFIG_TCC_SEMLOCK 0: the upstream default pulls in <dispatch/dispatch.h> on macOS, <semaphore.h> on Linux, and CRITICAL_SECTION on Windows -- none of which c5 ships today. tinycc uses the lock only to serialize libtcc state across threads; the bringup compile + self-host fixed point is single-threaded, so the lock is unused here.

Layout

• setup.py -- fetch the source zip from the vendor-deps release and extract the curated set; idempotent. Drops the core tinycc .c / .h files flat into the demo dir, the cross-platform system headers under include/, the runtime helper sources under lib/, the upstream Windows headers under win32/include/ (mingw <stdio.h> etc. plus the Win32 API tree at win32/include/winapi/), and the Windows PE startup + DLL .def files under win32/lib/ (used to satisfy _start / __chkstk / -lkernel32 / -lmsvcrt at link time).
• smoke.py -- build-only smoke harness. Synthesizes config.h for the host, walks each TU through badc -c, tracks per-TU compile state, exits 0 when every TU compiles cleanly and the multi-TU link emits a working tcc binary.
• self_host.py -- five-tier fixed-point parity check (samples -> corpus -> bootstrap -> gen2-self -> functional). Builds a reference tcc with the host cc and a stage1 tcc with badc, then asserts each tier matches byte-for-byte and that the final binaries round-trip a hello world.
• tcc.c, tcc.h, ..., include/*.h, lib/*.c / *.S, win32/include/**, win32/lib/** -- vendored upstream sources (gitignored out of band; setup.py is the source of truth for what they are).