1 files changed, 279 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ir/dump.go b/src/cmd/compile/internal/ir/dump.go
new file mode 100644
index 0000000000..fe1410969f
--- /dev/null
+++ b/src/cmd/compile/internal/ir/dump.go
@@ -0,0 +1,279 @@
+// 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 ir
+
+import (
+	"fmt"
+	"io"
+	"os"
+	"reflect"
+	"regexp"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/types"
+	"cmd/internal/src"
+)
+
+// dump is like fdump but prints to stderr.
+func DumpAny(root interface{}, filter string, depth int) {
+	FDumpAny(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 FDumpAny(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", base.FmtPos(v))
+		return
+	}
+
+	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
+}