#!/bin/sh
# Build the TMS34010 LLVM compiler.
#
# Two modes:
#
#   upstream + patches (M0, default)
#     ./scripts/build-llvm.sh
#     Clones llvmorg-23.1.5 into build/llvm-clean, applies patches/llvm and
#     builds it.  This mode owns its clone and resets it, but refuses to touch
#     a checkout whose origin is not llvm-project.
#
#   compiler fork (M1 and later)
#     LLVM_SRC=$PWD/build/llvm-clean LLVM_BRANCH=tms34010 \
#       ./scripts/build-llvm.sh
#     LLVM_REPO=gitea@git.wut.ee:opencode.siil.arti.ee/llvm-tms34010.git \
#       LLVM_BRANCH=tms34010 ./scripts/build-llvm.sh
#     Build the fork branch in place.  Fork mode never checks out, resets,
#     cleans or patches the source tree; it only configures and builds it.
#
# Environment:
#   LLVM_SRC     source tree (default build/llvm-clean)
#   LLVM_BUILD   build tree (default build/llvm-clean-build)
#   LLVM_REPO    git URL to clone when LLVM_SRC does not exist
#   LLVM_BRANCH  branch to clone/build; setting this (or LLVM_REPO) selects
#                fork mode
set -eu
ROOT=$(cd "$(dirname "$0")/.." && pwd)
cd "$ROOT"
mkdir -p build
SRC=${LLVM_SRC:-build/llvm-clean}
BUILD=${LLVM_BUILD:-build/llvm-clean-build}
REPO=${LLVM_REPO:-}
BRANCH=${LLVM_BRANCH:-}
TAG=llvmorg-23.1.5

origin_url() {
    git -C "$1" config --get remote.origin.url 2>/dev/null || true
}

if [ -n "$REPO" ] || [ -n "$BRANCH" ]; then
    echo "== compiler fork mode: $SRC${BRANCH:+ (branch $BRANCH)}"
    if [ ! -e "$SRC/.git" ]; then
        [ -n "$REPO" ] || {
            echo "build-llvm: $SRC is not a git checkout; set LLVM_REPO to clone it" >&2
            exit 1
        }
        if [ -n "$BRANCH" ]; then
            git clone --branch "$BRANCH" "$REPO" "$SRC"
        else
            git clone "$REPO" "$SRC"
        fi
    fi
    if [ -n "$BRANCH" ]; then
        CURRENT=$(git -C "$SRC" rev-parse --abbrev-ref HEAD)
        if [ "$CURRENT" != "$BRANCH" ]; then
            echo "build-llvm: $SRC is on '$CURRENT', not '$BRANCH'" >&2
            echo "build-llvm: check the branch out first; fork mode never" >&2
            echo "build-llvm: modifies the source tree" >&2
            exit 1
        fi
    fi
else
    echo "== upstream + patches mode: $SRC (tag $TAG)"
    if [ -e "$SRC/.git" ]; then
        URL=$(origin_url "$SRC")
        case "$URL" in
        *llvm-project*) ;;
        *)
            echo "build-llvm: refusing to reset $SRC: origin is" >&2
            echo "build-llvm: '${URL:-<none>}', not llvm-project." >&2
            echo "build-llvm: use LLVM_REPO/LLVM_BRANCH for a compiler fork" >&2
            echo "build-llvm: checkout (default mode must not reset it)" >&2
            exit 1
            ;;
        esac
    else
        git clone --depth 1 --branch "$TAG" \
            https://github.com/llvm/llvm-project.git "$SRC"
    fi
    git -C "$SRC" checkout --detach "$TAG"
    git -C "$SRC" reset --hard
    git -C "$SRC" clean -fdx

    PATCHROOT=$(pwd)/patches/llvm
    for p in "$PATCHROOT"/*.patch; do
        [ -e "$p" ] || continue
        git -C "$SRC" apply "$p"
    done
fi

cmake -S "$SRC/llvm" -B "$BUILD" -G Ninja \
    -DCMAKE_BUILD_TYPE=Release -DLLVM_ENABLE_ASSERTIONS=ON \
    -DLLVM_ENABLE_PROJECTS=clang \
    -DLLVM_TARGETS_TO_BUILD="X86;TMS34010" \
    -DLLVM_INCLUDE_TESTS=ON -DLLVM_INCLUDE_EXAMPLES=OFF \
    -DLLVM_INCLUDE_BENCHMARKS=OFF
ninja -C "$BUILD" clang opt llc llvm-config FileCheck count not