Build infrastructure for the LLVM prebuilt packages that clice depends on.

1. build-llvm.yml in clice-io/clice triggers a build with a target LLVM version (e.g., 21.1.8).
2. The workflow clones upstream LLVM at llvmorg-$VERSION.
3. Patches from patches/$VERSION/ in this repo are applied in order.
4. LLVM is built across a 14-job matrix (3 OS x configurations).
5. release-llvm.yml prunes unused libraries and publishes to this repo's Releases as $VERSION+rN.

See /upgrade-llvm in clice-io/clice/.claude/commands/upgrade-llvm.md.

patches/
  21.1.8/
    0001-codegen-fix-illegal-std-template-specializations.patch

Patches are git apply-compatible diffs against the upstream tag. Numbered prefixes ensure deterministic order.

Releases use $VERSION+rN (e.g., 21.1.8+r2):

• $VERSION = upstream LLVM tag
• +rN increments when toolchain, patches, or build config change

When a release is published (e.g., 21.1.8+r2), this repo is tagged at the commit used for that build. To reproduce:

git clone --branch "21.1.8+r2" https://github.com/clice-io/clice-llvm.git

During development (tag doesn't exist yet), build-llvm uses main.

Each Release should record: