alchemy-gcc

The compilers Golden Sun was built with, for Alchemy.

agscc	Golden Sun's compiler, and The Lost Age's	a 2000-07-31 gcc 2.96 development snapshot
agbcc	the Thumb audio compiler	pret/agbcc, built as old_agbcc

Named for the job they do. A version number in a compiler's name is a lie waiting to happen: "gcc 2.96" was never an FSF release.

This repository once also carried gs2cc (a gcc 3.0.0 tree), on the assumption that The Lost Age needed a different compiler version. Alchemy's reconstruction work established otherwise: GS2 uses gcc 2.96 like GS1 (shared audio owners aside, which use agbcc in both games). gs2cc was never wired into a real build path and never had an approved digest for any host, so it was removed rather than kept as unused weight.

Where this came from, and what we changed

The first commit of this repository is those trees, untouched, straight from their upstreams. Everything after it is a commit with a reason. So:

make ours     # every file we modified, per tree, against untouched upstream
git log       # why each one changed

PROVENANCE.txt records the exact upstream commit behind each tree. agbcc's was identified by measurement rather than inheritance: da598c1d is the best match across all 203 commits in pret/agbcc's history.

This matters because the repository this replaced could not answer that question. Its compilers arrived already patched, and auditing them afterwards turned up 120 invented compiler options in the 2.96 tree and ten more in agbcc — five of which were dead and have since been removed at no cost to the match.

One compiler, one configuration

No build modes, no environment switches, and no compiler option gcc did not ship. When a function will not match, the answer is in the C. An invented option does not solve an unmatched function; it makes that function permanently unsolvable, because nothing outside this repository can reproduce it.

Exactly one change in this repository alters emitted bytes: ASM_OUTPUT_ALIGN emits .align N, 0, forcing zero-fill padding. It is alone in its own commit so that measuring it is a one-line revert. It has never actually been measured.

Build

Requirements: Rust/Cargo, a host C toolchain with make, and ARM binutils (arm-none-eabi-as, arm-none-eabi-ar, or devkitARM).

make                      # build and stage agscc into dist/
make test                 # codegen regressions
make install DECOMP=../alchemy

The build driver is Rust (src/main.rs) where pret/agbcc uses shell. dist/ is a staged runtime, not source.

Acknowledgements

The GCC developers, for gcc 2.96 and 3.0 — the compilers themselves, and a back end still legible twenty-five years later. Sources come from gcc-mirror/gcc; notices remain in each tree's COPYING and COPYING.LIB.

pret, whose agbcc is vendored here directly, and whose decompilation projects are the model this one follows: one compiler, one flag set, per-file overrides counted on one hand, and the discipline that the difference belongs in the source rather than behind a switch. pokeemerald is the reference for how a decomp survives years rather than months.

Coaltergeist, who did the original work of identifying which compiler built Golden Sun and assembling a toolchain that could reproduce it — including the determination, from testing, that GS1 shipped with 2.96 rather than 3.0. Independent measurement here reached the same conclusion. This repository was rebuilt from upstream rather than inherited so that its provenance is checkable, which is a statement about records, not about that work.

The Golden Sun community, for the documentation and reverse engineering that make any of this legible.

Source and publication boundary

The vendored trees are the corresponding source for the runtimes built here. Do not publish a staged binary without them. Keep COPYING* and the upstream notices with the source; this README is not a licence statement.