build: download and compile with wasi-sdk

internal/crosscompile/cosscompile.go

@@ -0,0 +1,62 @@
+package crosscompile
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"runtime"
+
+	"github.com/goplus/llgo/internal/env"
+	"github.com/goplus/llgo/internal/xtool/llvm"
+)
+
+type Export struct {
+	CCFLAGS []string
+	CFLAGS  []string
+	LDFLAGS []string
+}
+
+const wasiSdkUrl = "https://github.com/WebAssembly/wasi-sdk/releases/download/wasi-sdk-25/wasi-sdk-25.0-x86_64-macos.tar.gz"
+
+func cacheDir() string {
+	return filepath.Join(env.LLGoCacheDir(), "crosscompile")
+}
+
+func UseCrossCompileSDK(goos, goarch string) (export Export, err error) {
+	if runtime.GOOS == goos && runtime.GOARCH == goarch {
+		// not cross compile
+		return
+	}
+	if goarch == "wasm" {
+		sdkDir := filepath.Join(cacheDir(), llvm.GetTargetTriple(goos, goarch))
+		if _, err = os.Stat(sdkDir); err != nil {
+			if !errors.Is(err, fs.ErrNotExist) {
+				return
+			}
+			if err = downloadAndExtract(wasiSdkUrl, sdkDir); err != nil {
+				return
+			}
+		}
+		// Set up flags for the SDK
+		wasiSdkRoot := filepath.Join(sdkDir, "wasi-sdk-25.0-x86_64-macos")
+		sysrootDir := filepath.Join(wasiSdkRoot, "share", "wasi-sysroot")
+		libclangDir := filepath.Join(wasiSdkRoot, "lib", "clang", "19")
+		includeDir := filepath.Join(sysrootDir, "include", "wasm32-wasip1")
+		libDir := filepath.Join(sysrootDir, "lib", "wasm32-wasip1")
+
+		export.CCFLAGS = []string{
+			"--sysroot=" + sysrootDir,
+			"-resource-dir=" + libclangDir,
+		}
+		export.CFLAGS = []string{
+			"-I" + includeDir,
+		}
+		export.LDFLAGS = []string{
+			"-L" + libDir,
+		}
+		return
+	}
+	// TODO(lijie): supports other platforms
+	return
+}