1 files changed, 539 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/dwarfgen/scope_test.go b/src/cmd/compile/internal/dwarfgen/scope_test.go
new file mode 100644
index 0000000..3df4c34
--- /dev/null
+++ b/src/cmd/compile/internal/dwarfgen/scope_test.go
@@ -0,0 +1,539 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package dwarfgen
+
+import (
+	"debug/dwarf"
+	"fmt"
+	"internal/testenv"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"sort"
+	"strconv"
+	"strings"
+	"testing"
+
+	"cmd/internal/objfile"
+)
+
+type testline struct {
+	// line is one line of go source
+	line string
+
+	// scopes is a list of scope IDs of all the lexical scopes that this line
+	// of code belongs to.
+	// Scope IDs are assigned by traversing the tree of lexical blocks of a
+	// function in pre-order
+	// Scope IDs are function specific, i.e. scope 0 is always the root scope
+	// of the function that this line belongs to. Empty scopes are not assigned
+	// an ID (because they are not saved in debug_info).
+	// Scope 0 is always omitted from this list since all lines always belong
+	// to it.
+	scopes []int
+
+	// vars is the list of variables that belong in scopes[len(scopes)-1].
+	// Local variables are prefixed with "var ", formal parameters with "arg ".
+	// Must be ordered alphabetically.
+	// Set to nil to skip the check.
+	vars []string
+
+	// decl is the list of variables declared at this line.
+	decl []string
+
+	// declBefore is the list of variables declared at or before this line.
+	declBefore []string
+}
+
+var testfile = []testline{
+	{line: "package main"},
+	{line: "func f1(x int) { }"},
+	{line: "func f2(x int) { }"},
+	{line: "func f3(x int) { }"},
+	{line: "func f4(x int) { }"},
+	{line: "func f5(x int) { }"},
+	{line: "func f6(x int) { }"},
+	{line: "func fi(x interface{}) { if a, ok := x.(error); ok { a.Error() } }"},
+	{line: "func gret1() int { return 2 }"},
+	{line: "func gretbool() bool { return true }"},
+	{line: "func gret3() (int, int, int) { return 0, 1, 2 }"},
+	{line: "var v = []int{ 0, 1, 2 }"},
+	{line: "var ch = make(chan int)"},
+	{line: "var floatch = make(chan float64)"},
+	{line: "var iface interface{}"},
+	{line: "func TestNestedFor() {", vars: []string{"var a int"}},
+	{line: "	a := 0", decl: []string{"a"}},
+	{line: "	f1(a)"},
+	{line: "	for i := 0; i < 5; i++ {", scopes: []int{1}, vars: []string{"var i int"}, decl: []string{"i"}},
+	{line: "		f2(i)", scopes: []int{1}},
+	{line: "		for i := 0; i < 5; i++ {", scopes: []int{1, 2}, vars: []string{"var i int"}, decl: []string{"i"}},
+	{line: "			f3(i)", scopes: []int{1, 2}},
+	{line: "		}"},
+	{line: "		f4(i)", scopes: []int{1}},
+	{line: "	}"},
+	{line: "	f5(a)"},
+	{line: "}"},
+	{line: "func TestOas2() {", vars: []string{}},
+	{line: "	if a, b, c := gret3(); a != 1 {", scopes: []int{1}, vars: []string{"var a int", "var b int", "var c int"}},
+	{line: "		f1(a)", scopes: []int{1}},
+	{line: "		f1(b)", scopes: []int{1}},
+	{line: "		f1(c)", scopes: []int{1}},
+	{line: "	}"},
+	{line: "	for i, x := range v {", scopes: []int{2}, vars: []string{"var i int", "var x int"}},
+	{line: "		f1(i)", scopes: []int{2}},
+	{line: "		f1(x)", scopes: []int{2}},
+	{line: "	}"},
+	{line: "	if a, ok := <- ch; ok {", scopes: []int{3}, vars: []string{"var a int", "var ok bool"}},
+	{line: "		f1(a)", scopes: []int{3}},
+	{line: "	}"},
+	{line: "	if a, ok := iface.(int); ok {", scopes: []int{4}, vars: []string{"var a int", "var ok bool"}},
+	{line: "		f1(a)", scopes: []int{4}},
+	{line: "	}"},
+	{line: "}"},
+	{line: "func TestIfElse() {"},
+	{line: "	if x := gret1(); x != 0 {", scopes: []int{1}, vars: []string{"var x int"}},
+	{line: "		a := 0", scopes: []int{1, 2}, vars: []string{"var a int"}},
+	{line: "		f1(a); f1(x)", scopes: []int{1, 2}},
+	{line: "	} else {"},
+	{line: "		b := 1", scopes: []int{1, 3}, vars: []string{"var b int"}},
+	{line: "		f1(b); f1(x+1)", scopes: []int{1, 3}},
+	{line: "	}"},
+	{line: "}"},
+	{line: "func TestSwitch() {", vars: []string{}},
+	{line: "	switch x := gret1(); x {", scopes: []int{1}, vars: []string{"var x int"}},
+	{line: "	case 0:", scopes: []int{1, 2}},
+	{line: "		i := x + 5", scopes: []int{1, 2}, vars: []string{"var i int"}},
+	{line: "		f1(x); f1(i)", scopes: []int{1, 2}},
+	{line: "	case 1:", scopes: []int{1, 3}},
+	{line: "		j := x + 10", scopes: []int{1, 3}, vars: []string{"var j int"}},
+	{line: "		f1(x); f1(j)", scopes: []int{1, 3}},
+	{line: "	case 2:", scopes: []int{1, 4}},
+	{line: "		k := x + 2", scopes: []int{1, 4}, vars: []string{"var k int"}},
+	{line: "		f1(x); f1(k)", scopes: []int{1, 4}},
+	{line: "	}"},
+	{line: "}"},
+	{line: "func TestTypeSwitch() {", vars: []string{}},
+	{line: "	switch x := iface.(type) {"},
+	{line: "	case int:", scopes: []int{1}},
+	{line: "		f1(x)", scopes: []int{1}, vars: []string{"var x int"}},
+	{line: "	case uint8:", scopes: []int{2}},
+	{line: "		f1(int(x))", scopes: []int{2}, vars: []string{"var x uint8"}},
+	{line: "	case float64:", scopes: []int{3}},
+	{line: "		f1(int(x)+1)", scopes: []int{3}, vars: []string{"var x float64"}},
+	{line: "	}"},
+	{line: "}"},
+	{line: "func TestSelectScope() {"},
+	{line: "	select {"},
+	{line: "	case i := <- ch:", scopes: []int{1}},
+	{line: "		f1(i)", scopes: []int{1}, vars: []string{"var i int"}},
+	{line: "	case f := <- floatch:", scopes: []int{2}},
+	{line: "		f1(int(f))", scopes: []int{2}, vars: []string{"var f float64"}},
+	{line: "	}"},
+	{line: "}"},
+	{line: "func TestBlock() {", vars: []string{"var a int"}},
+	{line: "	a := 1"},
+	{line: "	{"},
+	{line: "		b := 2", scopes: []int{1}, vars: []string{"var b int"}},
+	{line: "		f1(b)", scopes: []int{1}},
+	{line: "		f1(a)", scopes: []int{1}},
+	{line: "	}"},
+	{line: "}"},
+	{line: "func TestDiscontiguousRanges() {", vars: []string{"var a int"}},
+	{line: "	a := 0"},
+	{line: "	f1(a)"},
+	{line: "	{"},
+	{line: "		b := 0", scopes: []int{1}, vars: []string{"var b int"}},
+	{line: "		f2(b)", scopes: []int{1}},
+	{line: "		if gretbool() {", scopes: []int{1}},
+	{line: "			c := 0", scopes: []int{1, 2}, vars: []string{"var c int"}},
+	{line: "			f3(c)", scopes: []int{1, 2}},
+	{line: "		} else {"},
+	{line: "			c := 1.1", scopes: []int{1, 3}, vars: []string{"var c float64"}},
+	{line: "			f4(int(c))", scopes: []int{1, 3}},
+	{line: "		}"},
+	{line: "		f5(b)", scopes: []int{1}},
+	{line: "	}"},
+	{line: "	f6(a)"},
+	{line: "}"},
+	{line: "func TestClosureScope() {", vars: []string{"var a int", "var b int", "var f func(int)"}},
+	{line: "	a := 1; b := 1"},
+	{line: "	f := func(c int) {", scopes: []int{0}, vars: []string{"arg c int", "var &b *int", "var a int", "var d int"}, declBefore: []string{"&b", "a"}},
+	{line: "		d := 3"},
+	{line: "		f1(c); f1(d)"},
+	{line: "		if e := 3; e != 0 {", scopes: []int{1}, vars: []string{"var e int"}},
+	{line: "			f1(e)", scopes: []int{1}},
+	{line: "			f1(a)", scopes: []int{1}},
+	{line: "			b = 2", scopes: []int{1}},
+	{line: "		}"},
+	{line: "	}"},
+	{line: "	f(3); f1(b)"},
+	{line: "}"},
+	{line: "func TestEscape() {"},
+	{line: "	a := 1", vars: []string{"var a int"}},
+	{line: "	{"},
+	{line: "		b := 2", scopes: []int{1}, vars: []string{"var &b *int", "var p *int"}},
+	{line: "		p := &b", scopes: []int{1}},
+	{line: "		f1(a)", scopes: []int{1}},
+	{line: "		fi(p)", scopes: []int{1}},
+	{line: "	}"},
+	{line: "}"},
+	{line: "var fglob func() int"},
+	{line: "func TestCaptureVar(flag bool) {"},
+	{line: "	a := 1", vars: []string{"arg flag bool", "var a int"}}, // TODO(register args) restore "arg ~r1 func() int",
+	{line: "	if flag {"},
+	{line: "		b := 2", scopes: []int{1}, vars: []string{"var b int", "var f func() int"}},
+	{line: "		f := func() int {", scopes: []int{1, 0}},
+	{line: "			return b + 1"},
+	{line: "		}"},
+	{line: "		fglob = f", scopes: []int{1}},
+	{line: "	}"},
+	{line: "	f1(a)"},
+	{line: "}"},
+	{line: "func main() {"},
+	{line: "	TestNestedFor()"},
+	{line: "	TestOas2()"},
+	{line: "	TestIfElse()"},
+	{line: "	TestSwitch()"},
+	{line: "	TestTypeSwitch()"},
+	{line: "	TestSelectScope()"},
+	{line: "	TestBlock()"},
+	{line: "	TestDiscontiguousRanges()"},
+	{line: "	TestClosureScope()"},
+	{line: "	TestEscape()"},
+	{line: "	TestCaptureVar(true)"},
+	{line: "}"},
+}
+
+const detailOutput = false
+
+// Compiles testfile checks that the description of lexical blocks emitted
+// by the linker in debug_info, for each function in the main package,
+// corresponds to what we expect it to be.
+func TestScopeRanges(t *testing.T) {
+	testenv.MustHaveGoBuild(t)
+	t.Parallel()
+
+	if runtime.GOOS == "plan9" {
+		t.Skip("skipping on plan9; no DWARF symbol table in executables")
+	}
+
+	dir, err := ioutil.TempDir("", "TestScopeRanges")
+	if err != nil {
+		t.Fatalf("could not create directory: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	src, f := gobuild(t, dir, false, testfile)
+	defer f.Close()
+
+	// the compiler uses forward slashes for paths even on windows
+	src = strings.Replace(src, "\\", "/", -1)
+
+	pcln, err := f.PCLineTable()
+	if err != nil {
+		t.Fatal(err)
+	}
+	dwarfData, err := f.DWARF()
+	if err != nil {
+		t.Fatal(err)
+	}
+	dwarfReader := dwarfData.Reader()
+
+	lines := make(map[line][]*lexblock)
+
+	for {
+		entry, err := dwarfReader.Next()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if entry == nil {
+			break
+		}
+
+		if entry.Tag != dwarf.TagSubprogram {
+			continue
+		}
+
+		name, ok := entry.Val(dwarf.AttrName).(string)
+		if !ok || !strings.HasPrefix(name, "main.Test") {
+			continue
+		}
+
+		var scope lexblock
+		ctxt := scopexplainContext{
+			dwarfData:   dwarfData,
+			dwarfReader: dwarfReader,
+			scopegen:    1,
+		}
+
+		readScope(&ctxt, &scope, entry)
+
+		scope.markLines(pcln, lines)
+	}
+
+	anyerror := false
+	for i := range testfile {
+		tgt := testfile[i].scopes
+		out := lines[line{src, i + 1}]
+
+		if detailOutput {
+			t.Logf("%s // %v", testfile[i].line, out)
+		}
+
+		scopesok := checkScopes(tgt, out)
+		if !scopesok {
+			t.Logf("mismatch at line %d %q: expected: %v got: %v\n", i, testfile[i].line, tgt, scopesToString(out))
+		}
+
+		varsok := true
+		if testfile[i].vars != nil {
+			if len(out) > 0 {
+				varsok = checkVars(testfile[i].vars, out[len(out)-1].vars)
+				if !varsok {
+					t.Logf("variable mismatch at line %d %q for scope %d: expected: %v got: %v\n", i+1, testfile[i].line, out[len(out)-1].id, testfile[i].vars, out[len(out)-1].vars)
+				}
+				for j := range testfile[i].decl {
+					if line := declLineForVar(out[len(out)-1].vars, testfile[i].decl[j]); line != i+1 {
+						t.Errorf("wrong declaration line for variable %s, expected %d got: %d", testfile[i].decl[j], i+1, line)
+					}
+				}
+
+				for j := range testfile[i].declBefore {
+					if line := declLineForVar(out[len(out)-1].vars, testfile[i].declBefore[j]); line > i+1 {
+						t.Errorf("wrong declaration line for variable %s, expected %d (or less) got: %d", testfile[i].declBefore[j], i+1, line)
+					}
+				}
+			}
+		}
+
+		anyerror = anyerror || !scopesok || !varsok
+	}
+
+	if anyerror {
+		t.Fatalf("mismatched output")
+	}
+}
+
+func scopesToString(v []*lexblock) string {
+	r := make([]string, len(v))
+	for i, s := range v {
+		r[i] = strconv.Itoa(s.id)
+	}
+	return "[ " + strings.Join(r, ", ") + " ]"
+}
+
+func checkScopes(tgt []int, out []*lexblock) bool {
+	if len(out) > 0 {
+		// omit scope 0
+		out = out[1:]
+	}
+	if len(tgt) != len(out) {
+		return false
+	}
+	for i := range tgt {
+		if tgt[i] != out[i].id {
+			return false
+		}
+	}
+	return true
+}
+
+func checkVars(tgt []string, out []variable) bool {
+	if len(tgt) != len(out) {
+		return false
+	}
+	for i := range tgt {
+		if tgt[i] != out[i].expr {
+			return false
+		}
+	}
+	return true
+}
+
+func declLineForVar(scope []variable, name string) int {
+	for i := range scope {
+		if scope[i].name() == name {
+			return scope[i].declLine
+		}
+	}
+	return -1
+}
+
+type lexblock struct {
+	id     int
+	ranges [][2]uint64
+	vars   []variable
+	scopes []lexblock
+}
+
+type variable struct {
+	expr     string
+	declLine int
+}
+
+func (v *variable) name() string {
+	return strings.Split(v.expr, " ")[1]
+}
+
+type line struct {
+	file   string
+	lineno int
+}
+
+type scopexplainContext struct {
+	dwarfData   *dwarf.Data
+	dwarfReader *dwarf.Reader
+	scopegen    int
+}
+
+// readScope reads the DW_TAG_lexical_block or the DW_TAG_subprogram in
+// entry and writes a description in scope.
+// Nested DW_TAG_lexical_block entries are read recursively.
+func readScope(ctxt *scopexplainContext, scope *lexblock, entry *dwarf.Entry) {
+	var err error
+	scope.ranges, err = ctxt.dwarfData.Ranges(entry)
+	if err != nil {
+		panic(err)
+	}
+	for {
+		e, err := ctxt.dwarfReader.Next()
+		if err != nil {
+			panic(err)
+		}
+		switch e.Tag {
+		case 0:
+			sort.Slice(scope.vars, func(i, j int) bool {
+				return scope.vars[i].expr < scope.vars[j].expr
+			})
+			return
+		case dwarf.TagFormalParameter:
+			typ, err := ctxt.dwarfData.Type(e.Val(dwarf.AttrType).(dwarf.Offset))
+			if err != nil {
+				panic(err)
+			}
+			scope.vars = append(scope.vars, entryToVar(e, "arg", typ))
+		case dwarf.TagVariable:
+			typ, err := ctxt.dwarfData.Type(e.Val(dwarf.AttrType).(dwarf.Offset))
+			if err != nil {
+				panic(err)
+			}
+			scope.vars = append(scope.vars, entryToVar(e, "var", typ))
+		case dwarf.TagLexDwarfBlock:
+			scope.scopes = append(scope.scopes, lexblock{id: ctxt.scopegen})
+			ctxt.scopegen++
+			readScope(ctxt, &scope.scopes[len(scope.scopes)-1], e)
+		}
+	}
+}
+
+func entryToVar(e *dwarf.Entry, kind string, typ dwarf.Type) variable {
+	return variable{
+		fmt.Sprintf("%s %s %s", kind, e.Val(dwarf.AttrName).(string), typ.String()),
+		int(e.Val(dwarf.AttrDeclLine).(int64)),
+	}
+}
+
+// markLines marks all lines that belong to this scope with this scope
+// Recursively calls markLines for all children scopes.
+func (scope *lexblock) markLines(pcln objfile.Liner, lines map[line][]*lexblock) {
+	for _, r := range scope.ranges {
+		for pc := r[0]; pc < r[1]; pc++ {
+			file, lineno, _ := pcln.PCToLine(pc)
+			l := line{file, lineno}
+			if len(lines[l]) == 0 || lines[l][len(lines[l])-1] != scope {
+				lines[l] = append(lines[l], scope)
+			}
+		}
+	}
+
+	for i := range scope.scopes {
+		scope.scopes[i].markLines(pcln, lines)
+	}
+}
+
+func gobuild(t *testing.T, dir string, optimized bool, testfile []testline) (string, *objfile.File) {
+	src := filepath.Join(dir, "test.go")
+	dst := filepath.Join(dir, "out.o")
+
+	f, err := os.Create(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	for i := range testfile {
+		f.Write([]byte(testfile[i].line))
+		f.Write([]byte{'\n'})
+	}
+	f.Close()
+
+	args := []string{"build"}
+	if !optimized {
+		args = append(args, "-gcflags=-N -l")
+	}
+	args = append(args, "-o", dst, src)
+
+	cmd := exec.Command(testenv.GoToolPath(t), args...)
+	if b, err := cmd.CombinedOutput(); err != nil {
+		t.Logf("build: %s\n", string(b))
+		t.Fatal(err)
+	}
+
+	pkg, err := objfile.Open(dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	return src, pkg
+}
+
+// TestEmptyDwarfRanges tests that no list entry in debug_ranges has start == end.
+// See issue #23928.
+func TestEmptyDwarfRanges(t *testing.T) {
+	testenv.MustHaveGoRun(t)
+	t.Parallel()
+
+	if runtime.GOOS == "plan9" {
+		t.Skip("skipping on plan9; no DWARF symbol table in executables")
+	}
+
+	dir, err := ioutil.TempDir("", "TestEmptyDwarfRanges")
+	if err != nil {
+		t.Fatalf("could not create directory: %v", err)
+	}
+	defer os.RemoveAll(dir)
+
+	_, f := gobuild(t, dir, true, []testline{{line: "package main"}, {line: "func main(){ println(\"hello\") }"}})
+	defer f.Close()
+
+	dwarfData, err := f.DWARF()
+	if err != nil {
+		t.Fatal(err)
+	}
+	dwarfReader := dwarfData.Reader()
+
+	for {
+		entry, err := dwarfReader.Next()
+		if err != nil {
+			t.Fatal(err)
+		}
+		if entry == nil {
+			break
+		}
+
+		ranges, err := dwarfData.Ranges(entry)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if ranges == nil {
+			continue
+		}
+
+		for _, rng := range ranges {
+			if rng[0] == rng[1] {
+				t.Errorf("range entry with start == end: %v", rng)
+			}
+		}
+	}
+}