src/cmd/compile/internal/gc/dump.go - go - Git at Google

 // Copyright 2018 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.

 // This file implements textual dumping of arbitrary data structures
 // for debugging purposes. The code is customized for Node graphs
 // and may be used for an alternative view of the node structure.

 package gc

 import (
 	"cmd/compile/internal/types"
 	"cmd/internal/src"
 	"fmt"
 	"io"
 	"os"
 	"reflect"
 	"regexp"
 )

 // dump is like fdump but prints to stderr.
 func dump(root interface{}, filter string, depth int) {
 	fdump(os.Stderr, root, filter, depth)
 }

 // fdump prints the structure of a rooted data structure
 // to w by depth-first traversal of the data structure.
 //
 // The filter parameter is a regular expression. If it is
 // non-empty, only struct fields whose names match filter
 // are printed.
 //
 // The depth parameter controls how deep traversal recurses
 // before it returns (higher value means greater depth).
 // If an empty field filter is given, a good depth default value
 // is 4. A negative depth means no depth limit, which may be fine
 // for small data structures or if there is a non-empty filter.
 //
 // In the output, Node structs are identified by their Op name
 // rather than their type; struct fields with zero values or
 // non-matching field names are omitted, and "…" means recursion
 // depth has been reached or struct fields have been omitted.
 func fdump(w io.Writer, root interface{}, filter string, depth int) {
 	if root == nil {
 		fmt.Fprintln(w, "nil")
 		return
 	}

 	if filter == "" {
 		filter = ".*" // default
 	}

 	p := dumper{
 		output:  w,
 		fieldrx: regexp.MustCompile(filter),
 		ptrmap:  make(map[uintptr]int),
 		last:    '\n', // force printing of line number on first line
 	}

 	p.dump(reflect.ValueOf(root), depth)
 	p.printf("\n")
 }

 type dumper struct {
 	output  io.Writer
 	fieldrx *regexp.Regexp  // field name filter
 	ptrmap  map[uintptr]int // ptr -> dump line number
 	lastadr string          // last address string printed (for shortening)

 	// output
 	indent int  // current indentation level
 	last   byte // last byte processed by Write
 	line   int  // current line number
 }

 var indentBytes = []byte(".  ")

 func (p *dumper) Write(data []byte) (n int, err error) {
 	var m int
 	for i, b := range data {
 		// invariant: data[0:n] has been written
 		if b == '\n' {
 			m, err = p.output.Write(data[n : i+1])
 			n += m
 			if err != nil {
 				return
 			}
 		} else if p.last == '\n' {
 			p.line++
 			_, err = fmt.Fprintf(p.output, "%6d  ", p.line)
 			if err != nil {
 				return
 			}
 			for j := p.indent; j > 0; j-- {
 				_, err = p.output.Write(indentBytes)
 				if err != nil {
 					return
 				}
 			}
 		}
 		p.last = b
 	}
 	if len(data) > n {
 		m, err = p.output.Write(data[n:])
 		n += m
 	}
 	return
 }

 // printf is a convenience wrapper.
 func (p *dumper) printf(format string, args ...interface{}) {
 	if _, err := fmt.Fprintf(p, format, args...); err != nil {
 		panic(err)
 	}
 }

 // addr returns the (hexadecimal) address string of the object
 // represented by x (or "?" if x is not addressable), with the
 // common prefix between this and the prior address replaced by
 // "0x…" to make it easier to visually match addresses.
 func (p *dumper) addr(x reflect.Value) string {
 	if !x.CanAddr() {
 		return "?"
 	}
 	adr := fmt.Sprintf("%p", x.Addr().Interface())
 	s := adr
 	if i := commonPrefixLen(p.lastadr, adr); i > 0 {
 		s = "0x…" + adr[i:]
 	}
 	p.lastadr = adr
 	return s
 }

 // dump prints the contents of x.
 func (p *dumper) dump(x reflect.Value, depth int) {
 	if depth == 0 {
 		p.printf("…")
 		return
 	}

 	// special cases
 	switch v := x.Interface().(type) {
 	case Nodes:
 		// unpack Nodes since reflect cannot look inside
 		// due to the unexported field in its struct
 		x = reflect.ValueOf(v.Slice())

 	case src.XPos:
 		p.printf("%s", linestr(v))
 		return

 	case *types.Node:
 		x = reflect.ValueOf(asNode(v))
 	}

 	switch x.Kind() {
 	case reflect.String:
 		p.printf("%q", x.Interface()) // print strings in quotes

 	case reflect.Interface:
 		if x.IsNil() {
 			p.printf("nil")
 			return
 		}
 		p.dump(x.Elem(), depth-1)

 	case reflect.Ptr:
 		if x.IsNil() {
 			p.printf("nil")
 			return
 		}

 		p.printf("*")
 		ptr := x.Pointer()
 		if line, exists := p.ptrmap[ptr]; exists {
 			p.printf("(@%d)", line)
 			return
 		}
 		p.ptrmap[ptr] = p.line
 		p.dump(x.Elem(), depth) // don't count pointer indirection towards depth

 	case reflect.Slice:
 		if x.IsNil() {
 			p.printf("nil")
 			return
 		}
 		p.printf("%s (%d entries) {", x.Type(), x.Len())
 		if x.Len() > 0 {
 			p.indent++
 			p.printf("\n")
 			for i, n := 0, x.Len(); i < n; i++ {
 				p.printf("%d: ", i)
 				p.dump(x.Index(i), depth-1)
 				p.printf("\n")
 			}
 			p.indent--
 		}
 		p.printf("}")

 	case reflect.Struct:
 		typ := x.Type()

 		isNode := false
 		if n, ok := x.Interface().(Node); ok {
 			isNode = true
 			p.printf("%s %s {", n.Op.String(), p.addr(x))
 		} else {
 			p.printf("%s {", typ)
 		}
 		p.indent++

 		first := true
 		omitted := false
 		for i, n := 0, typ.NumField(); i < n; i++ {
 			// Exclude non-exported fields because their
 			// values cannot be accessed via reflection.
 			if name := typ.Field(i).Name; types.IsExported(name) {
 				if !p.fieldrx.MatchString(name) {
 					omitted = true
 					continue // field name not selected by filter
 				}

 				// special cases
 				if isNode && name == "Op" {
 					omitted = true
 					continue // Op field already printed for Nodes
 				}
 				x := x.Field(i)
 				if isZeroVal(x) {
 					omitted = true
 					continue // exclude zero-valued fields
 				}
 				if n, ok := x.Interface().(Nodes); ok && n.Len() == 0 {
 					omitted = true
 					continue // exclude empty Nodes slices
 				}

 				if first {
 					p.printf("\n")
 					first = false
 				}
 				p.printf("%s: ", name)
 				p.dump(x, depth-1)
 				p.printf("\n")
 			}
 		}
 		if omitted {
 			p.printf("…\n")
 		}

 		p.indent--
 		p.printf("}")

 	default:
 		p.printf("%v", x.Interface())
 	}
 }

 func isZeroVal(x reflect.Value) bool {
 	switch x.Kind() {
 	case reflect.Bool:
 		return !x.Bool()
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		return x.Int() == 0
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
 		return x.Uint() == 0
 	case reflect.String:
 		return x.String() == ""
 	case reflect.Interface, reflect.Ptr, reflect.Slice:
 		return x.IsNil()
 	}
 	return false
 }

 func commonPrefixLen(a, b string) (i int) {
 	for i < len(a) && i < len(b) && a[i] == b[i] {
 		i++
 	}
 	return
 }
	// Copyright 2018 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.

	// This file implements textual dumping of arbitrary data structures
	// for debugging purposes. The code is customized for Node graphs
	// and may be used for an alternative view of the node structure.

	package gc

	import (
	"cmd/compile/internal/types"
	"cmd/internal/src"
	"fmt"
	"io"
	"os"
	"reflect"
	"regexp"
	)

	// dump is like fdump but prints to stderr.
	func dump(root interface{}, filter string, depth int) {
	fdump(os.Stderr, root, filter, depth)
	}

	// fdump prints the structure of a rooted data structure
	// to w by depth-first traversal of the data structure.
	//
	// The filter parameter is a regular expression. If it is
	// non-empty, only struct fields whose names match filter
	// are printed.
	//
	// The depth parameter controls how deep traversal recurses
	// before it returns (higher value means greater depth).
	// If an empty field filter is given, a good depth default value
	// is 4. A negative depth means no depth limit, which may be fine
	// for small data structures or if there is a non-empty filter.
	//
	// In the output, Node structs are identified by their Op name
	// rather than their type; struct fields with zero values or
	// non-matching field names are omitted, and "…" means recursion
	// depth has been reached or struct fields have been omitted.
	func fdump(w io.Writer, root interface{}, filter string, depth int) {
	if root == nil {
	fmt.Fprintln(w, "nil")
	return
	}

	if filter == "" {
	filter = ".*" // default
	}

	p := dumper{
	output: w,
	fieldrx: regexp.MustCompile(filter),
	ptrmap: make(map[uintptr]int),
	last: '\n', // force printing of line number on first line
	}

	p.dump(reflect.ValueOf(root), depth)
	p.printf("\n")
	}

	type dumper struct {
	output io.Writer
	fieldrx *regexp.Regexp // field name filter
	ptrmap map[uintptr]int // ptr -> dump line number
	lastadr string // last address string printed (for shortening)

	// output
	indent int // current indentation level
	last byte // last byte processed by Write
	line int // current line number
	}

	var indentBytes = []byte(". ")

	func (p *dumper) Write(data []byte) (n int, err error) {
	var m int
	for i, b := range data {
	// invariant: data[0:n] has been written
	if b == '\n' {
	m, err = p.output.Write(data[n : i+1])
	n += m
	if err != nil {
	return
	}
	} else if p.last == '\n' {
	p.line++
	_, err = fmt.Fprintf(p.output, "%6d ", p.line)
	if err != nil {
	return
	}
	for j := p.indent; j > 0; j-- {
	_, err = p.output.Write(indentBytes)
	if err != nil {
	return
	}
	}
	}
	p.last = b
	}
	if len(data) > n {
	m, err = p.output.Write(data[n:])
	n += m
	}
	return
	}

	// printf is a convenience wrapper.
	func (p *dumper) printf(format string, args ...interface{}) {
	if _, err := fmt.Fprintf(p, format, args...); err != nil {
	panic(err)
	}
	}

	// addr returns the (hexadecimal) address string of the object
	// represented by x (or "?" if x is not addressable), with the
	// common prefix between this and the prior address replaced by
	// "0x…" to make it easier to visually match addresses.
	func (p *dumper) addr(x reflect.Value) string {
	if !x.CanAddr() {
	return "?"
	}
	adr := fmt.Sprintf("%p", x.Addr().Interface())
	s := adr
	if i := commonPrefixLen(p.lastadr, adr); i > 0 {
	s = "0x…" + adr[i:]
	}
	p.lastadr = adr
	return s
	}

	// dump prints the contents of x.
	func (p *dumper) dump(x reflect.Value, depth int) {
	if depth == 0 {
	p.printf("…")
	return
	}

	// special cases
	switch v := x.Interface().(type) {
	case Nodes:
	// unpack Nodes since reflect cannot look inside
	// due to the unexported field in its struct
	x = reflect.ValueOf(v.Slice())

	case src.XPos:
	p.printf("%s", linestr(v))
	return

	case *types.Node:
	x = reflect.ValueOf(asNode(v))
	}

	switch x.Kind() {
	case reflect.String:
	p.printf("%q", x.Interface()) // print strings in quotes

	case reflect.Interface:
	if x.IsNil() {
	p.printf("nil")
	return
	}
	p.dump(x.Elem(), depth-1)

	case reflect.Ptr:
	if x.IsNil() {
	p.printf("nil")
	return
	}

	p.printf("*")
	ptr := x.Pointer()
	if line, exists := p.ptrmap[ptr]; exists {
	p.printf("(@%d)", line)
	return
	}
	p.ptrmap[ptr] = p.line
	p.dump(x.Elem(), depth) // don't count pointer indirection towards depth

	case reflect.Slice:
	if x.IsNil() {
	p.printf("nil")
	return
	}
	p.printf("%s (%d entries) {", x.Type(), x.Len())
	if x.Len() > 0 {
	p.indent++
	p.printf("\n")
	for i, n := 0, x.Len(); i < n; i++ {
	p.printf("%d: ", i)
	p.dump(x.Index(i), depth-1)
	p.printf("\n")
	}
	p.indent--
	}
	p.printf("}")

	case reflect.Struct:
	typ := x.Type()

	isNode := false
	if n, ok := x.Interface().(Node); ok {
	isNode = true
	p.printf("%s %s {", n.Op.String(), p.addr(x))
	} else {
	p.printf("%s {", typ)
	}
	p.indent++

	first := true
	omitted := false
	for i, n := 0, typ.NumField(); i < n; i++ {
	// Exclude non-exported fields because their
	// values cannot be accessed via reflection.
	if name := typ.Field(i).Name; types.IsExported(name) {
	if !p.fieldrx.MatchString(name) {
	omitted = true
	continue // field name not selected by filter
	}

	// special cases
	if isNode && name == "Op" {
	omitted = true
	continue // Op field already printed for Nodes
	}
	x := x.Field(i)
	if isZeroVal(x) {
	omitted = true
	continue // exclude zero-valued fields
	}
	if n, ok := x.Interface().(Nodes); ok && n.Len() == 0 {
	omitted = true
	continue // exclude empty Nodes slices
	}

	if first {
	p.printf("\n")
	first = false
	}
	p.printf("%s: ", name)
	p.dump(x, depth-1)
	p.printf("\n")
	}
	}
	if omitted {
	p.printf("…\n")
	}

	p.indent--
	p.printf("}")

	default:
	p.printf("%v", x.Interface())
	}
	}

	func isZeroVal(x reflect.Value) bool {
	switch x.Kind() {
	case reflect.Bool:
	return !x.Bool()
	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
	return x.Int() == 0
	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
	return x.Uint() == 0
	case reflect.String:
	return x.String() == ""
	case reflect.Interface, reflect.Ptr, reflect.Slice:
	return x.IsNil()
	}
	return false
	}

	func commonPrefixLen(a, b string) (i int) {
	for i < len(a) && i < len(b) && a[i] == b[i] {
	i++
	}
	return
	}