From 7f3d1d6375278377ca0b179436a9079add1722ce Mon Sep 17 00:00:00 2001
From: Ophestra <cat@gensokyo.uk>
Date: Mon, 19 Jan 2026 02:27:45 +0900
Subject: [PATCH] internal/rosa: llvm artifact abstraction

The llvm bootstrap is multi-stage by nature, and cannot be completed in a single artifact.

Signed-off-by: Ophestra <cat@gensokyo.uk>
---
 internal/rosa/llvm.go | 191 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 191 insertions(+)
 create mode 100644 internal/rosa/llvm.go

diff --git a/internal/rosa/llvm.go b/internal/rosa/llvm.go
new file mode 100644
index 0000000..e3eccc8
--- /dev/null
+++ b/internal/rosa/llvm.go
@@ -0,0 +1,191 @@
+package rosa
+
+import (
+	"slices"
+	"strconv"
+	"strings"
+
+	"hakurei.app/container/check"
+	"hakurei.app/internal/pkg"
+)
+
+// llvmAttr holds the attributes that will be applied to a new [pkg.Artifact]
+// containing a LLVM variant.
+type llvmAttr struct {
+	flags int
+
+	// Concatenated with default environment for CMakeAttr.Env.
+	env []string
+	// Concatenated with generated entries for CMakeAttr.Cache.
+	cmake [][2]string
+	// Override CMakeAttr.Append.
+	append []string
+	// Concatenated with default dependencies for CMakeAttr.Extra.
+	extra []pkg.Artifact
+	// Concatenated with default fixup for CMakeAttr.Script.
+	script string
+	// Passed through to CMakeAttr.Prefix.
+	prefix *check.Absolute
+}
+
+const (
+	llvmProjectClang = 1 << iota
+	llvmProjectLld
+
+	llvmProjectAll = 1<<iota - 1
+
+	llvmRuntimeCompilerRT = 1 << iota
+	llvmRuntimeLibunwind
+	llvmRuntimeLibc
+	llvmRuntimeLibcxx
+	llvmRuntimeLibcxxABI
+
+	llvmAll        = 1<<iota - 1
+	llvmRuntimeAll = llvmAll - (2 * llvmProjectAll) - 1
+)
+
+// llvmFlagName resolves a llvmAttr.flags project or runtime flag to its name.
+func llvmFlagName(flag int) string {
+	switch flag {
+	case llvmProjectClang:
+		return "clang"
+	case llvmProjectLld:
+		return "lld"
+
+	case llvmRuntimeCompilerRT:
+		return "compiler-rt"
+	case llvmRuntimeLibunwind:
+		return "libunwind"
+	case llvmRuntimeLibc:
+		return "libc"
+	case llvmRuntimeLibcxx:
+		return "libcxx"
+	case llvmRuntimeLibcxxABI:
+		return "libcxxabi"
+
+	default:
+		panic("invalid flag " + strconv.Itoa(flag))
+	}
+}
+
+// newLLVM returns a [pkg.Artifact] containing a LLVM variant.
+func (t Toolchain) newLLVM(variant string, attr *llvmAttr) pkg.Artifact {
+	const (
+		version  = "21.1.8"
+		checksum = "8SUpqDkcgwOPsqHVtmf9kXfFeVmjVxl4LMn-qSE1AI_Xoeju-9HaoPNGtidyxyka"
+	)
+	if attr == nil {
+		panic("LLVM attr must be non-nil")
+	}
+
+	var projects, runtimes []string
+	for i := 1; i < llvmProjectAll; i <<= 1 {
+		if attr.flags&i != 0 {
+			projects = append(projects, llvmFlagName(i))
+		}
+	}
+	for i := (llvmProjectAll + 1) << 1; i < llvmRuntimeAll; i <<= 1 {
+		if attr.flags&i != 0 {
+			runtimes = append(runtimes, llvmFlagName(i))
+		}
+	}
+
+	var script, scriptEarly string
+
+	cache := [][2]string{
+		{"CMAKE_BUILD_TYPE", "Release"},
+
+		{"LLVM_HOST_TRIPLE", `"${ROSA_TRIPLE}"`},
+		{"LLVM_DEFAULT_TARGET_TRIPLE", `"${ROSA_TRIPLE}"`},
+	}
+	if len(projects) > 0 {
+		cache = append(cache,
+			[2]string{"LLVM_ENABLE_PROJECTS", `"${ROSA_LLVM_PROJECTS}"`})
+	}
+	if len(runtimes) > 0 {
+		cache = append(cache,
+			[2]string{"LLVM_ENABLE_RUNTIMES", `"${ROSA_LLVM_RUNTIMES}"`})
+	}
+
+	cmakeAppend := []string{"llvm"}
+	if attr.append != nil {
+		cmakeAppend = attr.append
+	} else {
+		cache = append(cache,
+			[2]string{"LLVM_ENABLE_LIBCXX", "ON"},
+			[2]string{"LLVM_USE_LINKER", "lld"},
+
+			[2]string{"LLVM_INSTALL_BINUTILS_SYMLINKS", "ON"},
+			[2]string{"LLVM_INSTALL_CCTOOLS_SYMLINKS", "ON"},
+		)
+	}
+
+	extra := []pkg.Artifact{
+		t.NewPython(),
+		t.NewKernelHeaders(),
+	}
+	if t == toolchainStage3 {
+		extra = nil
+	}
+
+	if attr.flags&llvmProjectClang != 0 {
+		cache = append(cache,
+			[2]string{"CLANG_DEFAULT_CXX_STDLIB", "libc++"},
+			[2]string{"CLANG_DEFAULT_RTLIB", "compiler-rt"},
+		)
+	}
+	if attr.flags&llvmProjectLld != 0 {
+		script += `
+ln -s ld.lld /work/system/bin/ld
+`
+	}
+	if attr.flags&llvmRuntimeCompilerRT != 0 {
+		if attr.append == nil {
+			cache = append(cache,
+				[2]string{"COMPILER_RT_USE_LLVM_UNWINDER", "ON"})
+		}
+	}
+	if attr.flags&llvmRuntimeLibunwind != 0 {
+		cache = append(cache,
+			[2]string{"LIBUNWIND_USE_COMPILER_RT", "ON"})
+	}
+	if attr.flags&llvmRuntimeLibcxx != 0 {
+		cache = append(cache,
+			[2]string{"LIBCXX_HAS_MUSL_LIBC", "ON"},
+			[2]string{"LIBCXX_USE_COMPILER_RT", "ON"},
+		)
+
+		if t > toolchainStage3 {
+			// libcxxabi fails to compile if c++ headers not prefixed in /usr
+			// is found by the compiler, and doing this is easier than
+			// overriding CXXFLAGS; not using mv here to avoid chown failures
+			scriptEarly += `
+cp -r /system/include /usr/include && rm -rf /system/include
+`
+		}
+	}
+	if attr.flags&llvmRuntimeLibcxxABI != 0 {
+		cache = append(cache,
+			[2]string{"LIBCXXABI_USE_COMPILER_RT", "ON"},
+			[2]string{"LIBCXXABI_USE_LLVM_UNWINDER", "ON"},
+		)
+	}
+
+	return t.NewViaCMake("llvm", version, variant, pkg.NewHTTPGetTar(
+		nil, "https://github.com/llvm/llvm-project/archive/refs/tags/"+
+			"llvmorg-"+version+".tar.gz",
+		mustDecode(checksum),
+		pkg.TarGzip,
+	), &CMakeAttr{
+		Cache:  slices.Concat(cache, attr.cmake),
+		Append: cmakeAppend,
+		Extra:  slices.Concat(attr.extra, extra),
+		Prefix: attr.prefix,
+
+		Env: slices.Concat([]string{
+			"ROSA_LLVM_PROJECTS=" + strings.Join(projects, ";"),
+			"ROSA_LLVM_RUNTIMES=" + strings.Join(runtimes, ";"),
+		}, attr.env),
+		ScriptEarly: scriptEarly, Script: script + attr.script,
+	})
+}