ir: add metadata read APIs

ir.go

@@ -522,6 +522,22 @@ func (m Module) AddNamedMetadataOperand(name string, operand Metadata) {
 	defer C.free(unsafe.Pointer(cname))
 	C.LLVMAddNamedMetadataOperand2(m.C, cname, operand.C)
 }
+func (m Module) NamedMetadataNumOperands(name string) int {
+	cname := C.CString(name)
+	defer C.free(unsafe.Pointer(cname))
+	return int(C.LLVMGetNamedMetadataNumOperands(m.C, cname))
+}
+func (m Module) NamedMetadataOperands(name string) []Value {
+	cname := C.CString(name)
+	defer C.free(unsafe.Pointer(cname))
+	n := int(C.LLVMGetNamedMetadataNumOperands(m.C, cname))
+	if n == 0 {
+		return nil
+	}
+	values := make([]Value, n)
+	C.LLVMGetNamedMetadataOperands(m.C, cname, llvmValueRefPtr(&values[0]))
+	return values
+}
 
 func (m Module) Context() (c Context) {
 	c.C = C.LLVMGetModuleContext(m.C)
@@ -824,6 +840,26 @@ func (c Context) MDNode(mds []Metadata) (md Metadata) {
 	md.C = C.LLVMMDNode2(c.C, ptr, nvals)
 	return
 }
+func (v Value) MDNodeNumOperands() int {
+	return int(C.LLVMGetMDNodeNumOperands(v.C))
+}
+func (v Value) MDNodeOperands() []Value {
+	n := v.MDNodeNumOperands()
+	if n == 0 {
+		return nil
+	}
+	values := make([]Value, n)
+	C.LLVMGetMDNodeOperands(v.C, llvmValueRefPtr(&values[0]))
+	return values
+}
+func (v Value) IsAMDString() bool {
+	return C.LLVMIsAMDString(v.C) != nil
+}
+func (v Value) MDString() string {
+	var n C.unsigned
+	s := C.LLVMGetMDString(v.C, &n)
+	return C.GoStringN(s, C.int(n))
+}
 func (v Value) ConstantAsMetadata() (md Metadata) {
 	md.C = C.LLVMConstantAsMetadata(v.C)
 	return

metadata_test.go

@@ -0,0 +1,233 @@
+package llvm
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestNamedMetadataRoundTrip(t *testing.T) {
+	ctx := NewContext()
+	defer ctx.Dispose()
+
+	mod := ctx.NewModule("metadata_roundtrip")
+	defer mod.Dispose()
+
+	mdstr := func(s string) Metadata {
+		return ctx.MDString(s)
+	}
+	mdint := func(n uint64) Metadata {
+		return ConstInt(ctx.Int32Type(), n, false).ConstantAsMetadata()
+	}
+	addRow := func(name string, fields ...Metadata) {
+		mod.AddNamedMetadataOperand(name, ctx.MDNode(fields))
+	}
+
+	addRow("llgo.useiface",
+		mdstr("github.com/goplus/llgo/demo.main"),
+		mdstr("*_llgo_github.com/goplus/llgo/demo.File"),
+	)
+	addRow("llgo.useifacemethod",
+		mdstr("github.com/goplus/llgo/demo.consume"),
+		mdstr("_llgo_github.com/goplus/llgo/demo.ReadCloser"),
+		mdstr("Read"),
+		mdstr("_llgo_func$readsig"),
+	)
+	addRow("llgo.interfaceinfo",
+		mdstr("_llgo_github.com/goplus/llgo/demo.ReadCloser"),
+		mdstr("Read"),
+		mdstr("_llgo_func$readsig"),
+	)
+	addRow("llgo.interfaceinfo",
+		mdstr("_llgo_github.com/goplus/llgo/demo.ReadCloser"),
+		mdstr("Close"),
+		mdstr("_llgo_func$closesig"),
+	)
+	addRow("llgo.methodinfo",
+		mdstr("*_llgo_github.com/goplus/llgo/demo.File"),
+		mdint(0),
+		mdstr("Read"),
+		mdstr("_llgo_func$readsig"),
+		mdstr("github.com/goplus/llgo/demo.(*File).Read"),
+		mdstr("github.com/goplus/llgo/demo.File.Read"),
+	)
+	addRow("llgo.methodinfo",
+		mdstr("*_llgo_github.com/goplus/llgo/demo.File"),
+		mdint(1),
+		mdstr("Close"),
+		mdstr("_llgo_func$closesig"),
+		mdstr("github.com/goplus/llgo/demo.(*File).Close"),
+		mdstr("github.com/goplus/llgo/demo.File.Close"),
+	)
+	addRow("llgo.usenamedmethod",
+		mdstr("github.com/goplus/llgo/demo.lookup"),
+		mdstr("ServeHTTP"),
+	)
+	addRow("llgo.reflectmethod",
+		mdstr("github.com/goplus/llgo/demo.lookup"),
+	)
+
+	ir := mod.String()
+	for _, want := range []string{
+		`!llgo.useiface = !{!0}`,
+		`!0 = !{!"github.com/goplus/llgo/demo.main", !"*_llgo_github.com/goplus/llgo/demo.File"}`,
+		`!llgo.useifacemethod = !{!1}`,
+		`!1 = !{!"github.com/goplus/llgo/demo.consume", !"_llgo_github.com/goplus/llgo/demo.ReadCloser", !"Read", !"_llgo_func$readsig"}`,
+		`!llgo.interfaceinfo = !{!2, !3}`,
+		`!2 = !{!"_llgo_github.com/goplus/llgo/demo.ReadCloser", !"Read", !"_llgo_func$readsig"}`,
+		`!3 = !{!"_llgo_github.com/goplus/llgo/demo.ReadCloser", !"Close", !"_llgo_func$closesig"}`,
+		`!llgo.methodinfo = !{!4, !5}`,
+		`!4 = !{!"*_llgo_github.com/goplus/llgo/demo.File", i32 0, !"Read", !"_llgo_func$readsig", !"github.com/goplus/llgo/demo.(*File).Read", !"github.com/goplus/llgo/demo.File.Read"}`,
+		`!5 = !{!"*_llgo_github.com/goplus/llgo/demo.File", i32 1, !"Close", !"_llgo_func$closesig", !"github.com/goplus/llgo/demo.(*File).Close", !"github.com/goplus/llgo/demo.File.Close"}`,
+		`!llgo.usenamedmethod = !{!6}`,
+		`!6 = !{!"github.com/goplus/llgo/demo.lookup", !"ServeHTTP"}`,
+		`!llgo.reflectmethod = !{!7}`,
+		`!7 = !{!"github.com/goplus/llgo/demo.lookup"}`,
+	} {
+		if !strings.Contains(ir, want) {
+			t.Fatalf("module IR missing expected fragment:\n%s\n\nfull IR:\n%s", want, ir)
+		}
+	}
+
+	path := filepath.Join(t.TempDir(), "metadata.ll")
+	if err := os.WriteFile(path, []byte(ir), 0o600); err != nil {
+		t.Fatal(err)
+	}
+
+	parseCtx := NewContext()
+	defer parseCtx.Dispose()
+
+	buf, err := NewMemoryBufferFromFile(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	parsed, err := (&parseCtx).ParseIR(buf)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer parsed.Dispose()
+
+	if got := parsed.NamedMetadataNumOperands("llgo.useiface"); got != 1 {
+		t.Fatalf("NamedMetadataNumOperands(llgo.useiface) = %d, want 1", got)
+	}
+	if got := parsed.NamedMetadataNumOperands("llgo.interfaceinfo"); got != 2 {
+		t.Fatalf("NamedMetadataNumOperands(llgo.interfaceinfo) = %d, want 2", got)
+	}
+	if got := parsed.NamedMetadataNumOperands("llgo.methodinfo"); got != 2 {
+		t.Fatalf("NamedMetadataNumOperands(llgo.methodinfo) = %d, want 2", got)
+	}
+	if got := parsed.NamedMetadataNumOperands("llgo.missing"); got != 0 {
+		t.Fatalf("NamedMetadataNumOperands(llgo.missing) = %d, want 0", got)
+	}
+	if got := parsed.NamedMetadataOperands("llgo.missing"); len(got) != 0 {
+		t.Fatalf("NamedMetadataOperands(llgo.missing) returned %d rows, want 0", len(got))
+	}
+
+	useIfaceRows := parsed.NamedMetadataOperands("llgo.useiface")
+	requireMDStrings(t, useIfaceRows, 0,
+		"github.com/goplus/llgo/demo.main",
+		"*_llgo_github.com/goplus/llgo/demo.File",
+	)
+
+	useIfaceMethodRows := parsed.NamedMetadataOperands("llgo.useifacemethod")
+	requireMDStrings(t, useIfaceMethodRows, 0,
+		"github.com/goplus/llgo/demo.consume",
+		"_llgo_github.com/goplus/llgo/demo.ReadCloser",
+		"Read",
+		"_llgo_func$readsig",
+	)
+
+	interfaceInfoRows := parsed.NamedMetadataOperands("llgo.interfaceinfo")
+	requireMDStrings(t, interfaceInfoRows, 0,
+		"_llgo_github.com/goplus/llgo/demo.ReadCloser",
+		"Read",
+		"_llgo_func$readsig",
+	)
+	requireMDStrings(t, interfaceInfoRows, 1,
+		"_llgo_github.com/goplus/llgo/demo.ReadCloser",
+		"Close",
+		"_llgo_func$closesig",
+	)
+
+	methodInfoRows := parsed.NamedMetadataOperands("llgo.methodinfo")
+	requireMethodInfoRow(t, methodInfoRows, 0,
+		"*_llgo_github.com/goplus/llgo/demo.File",
+		0,
+		"Read",
+		"_llgo_func$readsig",
+		"github.com/goplus/llgo/demo.(*File).Read",
+		"github.com/goplus/llgo/demo.File.Read",
+	)
+	requireMethodInfoRow(t, methodInfoRows, 1,
+		"*_llgo_github.com/goplus/llgo/demo.File",
+		1,
+		"Close",
+		"_llgo_func$closesig",
+		"github.com/goplus/llgo/demo.(*File).Close",
+		"github.com/goplus/llgo/demo.File.Close",
+	)
+
+	useNamedMethodRows := parsed.NamedMetadataOperands("llgo.usenamedmethod")
+	requireMDStrings(t, useNamedMethodRows, 0,
+		"github.com/goplus/llgo/demo.lookup",
+		"ServeHTTP",
+	)
+
+	reflectMethodRows := parsed.NamedMetadataOperands("llgo.reflectmethod")
+	requireMDStrings(t, reflectMethodRows, 0,
+		"github.com/goplus/llgo/demo.lookup",
+	)
+}
+
+func requireMDStrings(t *testing.T, rows []Value, rowIndex int, want ...string) {
+	t.Helper()
+	if rowIndex >= len(rows) {
+		t.Fatalf("row index %d out of range for %d rows", rowIndex, len(rows))
+	}
+	fields := rows[rowIndex].MDNodeOperands()
+	if len(fields) != len(want) {
+		t.Fatalf("row %d has %d fields, want %d", rowIndex, len(fields), len(want))
+	}
+	for i, field := range fields {
+		if !field.IsAMDString() {
+			t.Fatalf("row %d field %d is not an MDString", rowIndex, i)
+		}
+		if got := field.MDString(); got != want[i] {
+			t.Fatalf("row %d field %d = %q, want %q", rowIndex, i, got, want[i])
+		}
+	}
+}
+
+func requireMethodInfoRow(t *testing.T, rows []Value, rowIndex int, wantType string, wantIndex uint64, wantName string, wantMType string, wantIFn string, wantTFn string) {
+	t.Helper()
+	if rowIndex >= len(rows) {
+		t.Fatalf("row index %d out of range for %d rows", rowIndex, len(rows))
+	}
+	fields := rows[rowIndex].MDNodeOperands()
+	if len(fields) != 6 {
+		t.Fatalf("methodinfo row %d has %d fields, want 6", rowIndex, len(fields))
+	}
+	if !fields[0].IsAMDString() {
+		t.Fatalf("methodinfo row %d field 0 is not an MDString", rowIndex)
+	}
+	if got := fields[0].MDString(); got != wantType {
+		t.Fatalf("methodinfo row %d field 0 = %q, want %q", rowIndex, got, wantType)
+	}
+	if fields[1].IsAMDString() {
+		t.Fatalf("methodinfo row %d field 1 unexpectedly reports MDString", rowIndex)
+	}
+	if got := fields[1].ZExtValue(); got != wantIndex {
+		t.Fatalf("methodinfo row %d field 1 = %d, want %d", rowIndex, got, wantIndex)
+	}
+	for i, want := range []string{wantName, wantMType, wantIFn, wantTFn} {
+		fieldIndex := i + 2
+		if !fields[fieldIndex].IsAMDString() {
+			t.Fatalf("methodinfo row %d field %d is not an MDString", rowIndex, fieldIndex)
+		}
+		if got := fields[fieldIndex].MDString(); got != want {
+			t.Fatalf("methodinfo row %d field %d = %q, want %q", rowIndex, fieldIndex, got, want)
+		}
+	}
+}