cli,compiler: support emitting debug info in a file

cli/smartcontract/smart_contract.go

@@ -92,6 +92,10 @@ func NewCommands() []cli.Command {
 						Name:  "debug, d",
 						Usage: "Debug mode will print out additional information after a compiling",
 					},
+					cli.StringFlag{
+						Name:  "emitdebug",
+						Usage: "Emit debug info in a separate file",
+					},
 				},
 			},
 			{
@@ -348,6 +352,8 @@ func contractCompile(ctx *cli.Context) error {
 	o := &compiler.Options{
 		Outfile: ctx.String("out"),
 		Debug:   ctx.Bool("debug"),
+
+		DebugInfo: ctx.String("emitdebug"),
 	}
 
 	result, err := compiler.CompileAndSave(src, o)

pkg/compiler/codegen.go

@@ -1313,19 +1313,19 @@ func newCodegen(info *buildInfo, pkg *loader.PackageInfo) *codegen {
 }
 
 // CodeGen compiles the program to bytecode.
-func CodeGen(info *buildInfo) ([]byte, error) {
+func CodeGen(info *buildInfo) ([]byte, *DebugInfo, error) {
 	pkg := info.program.Package(info.initialPackage)
 	c := newCodegen(info, pkg)
 
 	if err := c.compile(info, pkg); err != nil {
-		return nil, err
+		return nil, nil, err
 	}
 
 	buf := c.prog.Bytes()
 	if err := c.writeJumps(buf); err != nil {
-		return nil, err
+		return nil, nil, err
 	}
-	return buf, nil
+	return buf, c.emitDebugInfo(), nil
 }
 
 func (c *codegen) resolveFuncDecls(f *ast.File) {

pkg/compiler/compiler.go

@@ -2,11 +2,13 @@ package compiler
 
 import (
 	"bytes"
+	"encoding/json"
 	"fmt"
 	"go/parser"
 	"io"
 	"io/ioutil"
 	"os"
+	"path/filepath"
 	"strings"
 
 	"golang.org/x/tools/go/loader"
@@ -22,6 +24,9 @@ type Options struct {
 	// The name of the output file.
 	Outfile string
 
+	// The name of the output for debug info.
+	DebugInfo string
+
 	// Debug outputs a hex encoded string of the generated bytecode.
 	Debug bool
 }
@@ -52,12 +57,7 @@ func getBuildInfo(src interface{}) (*buildInfo, error) {
 
 // Compile compiles a Go program into bytecode that can run on the NEO virtual machine.
 func Compile(r io.Reader) ([]byte, error) {
-	ctx, err := getBuildInfo(r)
+	buf, _, err := CompileWithDebugInfo(r)
-	if err != nil {
-		return nil, err
-	}
-
-	buf, err := CodeGen(ctx)
 	if err != nil {
 		return nil, err
 	}
@@ -65,6 +65,15 @@ func Compile(r io.Reader) ([]byte, error) {
 	return buf, nil
 }
 
+// CompileWithDebugInfo compiles a Go program into bytecode and emits debug info.
+func CompileWithDebugInfo(r io.Reader) ([]byte, *DebugInfo, error) {
+	ctx, err := getBuildInfo(r)
+	if err != nil {
+		return nil, nil, err
+	}
+	return CodeGen(ctx)
+}
+
 // CompileAndSave will compile and save the file to disk.
 func CompileAndSave(src string, o *Options) ([]byte, error) {
 	if !strings.HasSuffix(src, ".go") {
@@ -81,11 +90,23 @@ func CompileAndSave(src string, o *Options) ([]byte, error) {
 	if err != nil {
 		return nil, err
 	}
-	b, err = Compile(bytes.NewReader(b))
+	b, di, err := CompileWithDebugInfo(bytes.NewReader(b))
 	if err != nil {
 		return nil, fmt.Errorf("error while trying to compile smart contract file: %v", err)
 	}
-
 	out := fmt.Sprintf("%s.%s", o.Outfile, o.Ext)
-	return b, ioutil.WriteFile(out, b, os.ModePerm)
+	err = ioutil.WriteFile(out, b, os.ModePerm)
+	if o.DebugInfo == "" {
+		return b, err
+	}
+	p, err := filepath.Abs(src)
+	if err != nil {
+		return b, err
+	}
+	di.Documents = append(di.Documents, p)
+	data, err := json.Marshal(di)
+	if err != nil {
+		return b, err
+	}
+	return b, ioutil.WriteFile(o.DebugInfo, data, os.ModePerm)
 }