func getPackage(pkgpath string) (*gobuild.Package, error) {
var ctx gobuild.Context = gobuild.Default
ctx.GOARCH = GOARCH
ctx.GOOS = GOOS
ctx.BuildTags = append(ctx.BuildTags[:], "llgo")
//ctx.Compiler = "llgo"
// Attempt to find an overlay package path,
// which we'll use in ReadDir below.
overlayentries := make(map[string]bool)
overlaypkgpath := llgoPkgPrefix + pkgpath
overlaypkg, err := ctx.Import(overlaypkgpath, "", gobuild.FindOnly)
if err != nil {
overlaypkg = nil
}
// ReadDir is overridden to return a fake ".s"
// file for each ".ll" file in the directory.
ctx.ReadDir = func(dir string) (fi []os.FileInfo, err error) {
fi, err = ioutil.ReadDir(dir)
if err != nil {
return nil, err
}
entries := make(map[string]os.FileInfo)
for _, info := range fi {
entries[info.Name()] = info
}
// Overlay all files in the overlay package dir.
// If we find any .ll files, replace the suffix
// with .s.
if overlaypkg != nil {
fi, err = ioutil.ReadDir(overlaypkg.Dir)
}
if err == nil {
// Check for .ll files in the overlay dir if
// we have one, else in the standard package dir.
for _, info := range fi {
name := info.Name()
if strings.HasSuffix(name, ".ll") {
name = name[:len(name)-3] + ".s"
info = &renamedFileInfo{info, name}
}
overlayentries[name] = true
entries[name] = info
}
}
fi = make([]os.FileInfo, 0, len(entries))
for _, info := range entries {
fi = append(fi, info)
}
return fi, nil
}
// OpenFile is overridden to return the contents
// of the ".ll" file found in ReadDir above. The
// returned ReadCloser is wrapped to transform
// LLVM IR comments to use "//", as expected by
// go/build when looking for build tags.
ctx.OpenFile = func(path string) (io.ReadCloser, error) {
base := filepath.Base(path)
overlay := overlayentries[base]
if overlay {
if overlaypkg != nil {
path = filepath.Join(overlaypkg.Dir, base)
}
if strings.HasSuffix(path, ".s") {
path := path[:len(path)-2] + ".ll"
var r io.ReadCloser
var err error
r, err = os.Open(path)
if err == nil {
r = build.NewLLVMIRReader(r)
}
return r, err
}
}
return os.Open(path)
}
pkg, err := ctx.Import(pkgpath, "", 0)
if err != nil {
return nil, err
} else {
if overlaypkg == nil {
overlaypkg = pkg
}
for i, filename := range pkg.GoFiles {
pkgdir := pkg.Dir
if overlayentries[filename] {
pkgdir = overlaypkg.Dir
}
pkg.GoFiles[i] = path.Join(pkgdir, filename)
}
for i, filename := range pkg.CFiles {
pkgdir := pkg.Dir
if overlayentries[filename] {
pkgdir = overlaypkg.Dir
}
pkg.CFiles[i] = path.Join(pkgdir, filename)
}
for i, filename := range pkg.SFiles {
pkgdir := pkg.Dir
if overlayentries[filename] {
pkgdir = overlaypkg.Dir
filename = filename[:len(filename)-2] + ".ll"
} else {
err := fmt.Errorf("No matching .ll file for %q", filename)
return nil, err
}
pkg.SFiles[i] = path.Join(pkgdir, filename)
}
}
return pkg, nil
}