add -bootstrap option to avogen

internal/cmd/avogen/main.go

@@ -8,6 +8,7 @@ import (
 	"path/filepath"
 
 	"github.com/mmcloughlin/avo/internal/gen"
+	"github.com/mmcloughlin/avo/internal/inst"
 	"github.com/mmcloughlin/avo/internal/load"
 )
 
@@ -17,15 +18,20 @@ var generators = map[string]gen.Builder{
 	"godatatest": gen.NewGoDataTest,
 }
 
-var datadir = flag.String(
+// Command-line flags.
+var (
+	bootstrap = flag.Bool("bootstrap", false, "regenerate instruction list from original data")
+	datadir   = flag.String(
 		"data",
 		filepath.Join(build.Default.GOPATH, "src/github.com/mmcloughlin/avo/internal/data"),
 		"path to data directory",
 	)
-
-var output = flag.String("output", "", "path to output file (default stdout)")
+	output = flag.String("output", "", "path to output file (default stdout)")
+)
 
 func main() {
+	log.SetPrefix("avogen: ")
+	log.SetFlags(0)
 	flag.Parse()
 
 	// Build generator.
@@ -51,11 +57,16 @@ func main() {
 	}
 
 	// Load instructions.
+	is := inst.Instructions
+	if *bootstrap {
+		log.Printf("bootstrap: loading instructions from data directory %s", *datadir)
 		l := load.NewLoaderFromDataDir(*datadir)
-	is, err := l.Load()
+		r, err := l.Load()
 		if err != nil {
 			log.Fatal(err)
 		}
+		is = r
+	}
 
 	// Generate output.
 	b, err := g.Generate(is)

internal/inst/table.go

@@ -1,7 +1,7 @@
 package inst
 
-//go:generate avogen -data ../data -output ztable.go godata
-//go:generate avogen -data ../data -output ztable_test.go godatatest
+//go:generate avogen -bootstrap -data ../data -output ztable.go godata
+//go:generate avogen -bootstrap -data ../data -output ztable_test.go godatatest
 
 func Lookup(opcode string) (Instruction, bool) {
 	for _, i := range Instructions {

internal/inst/ztable.go

@@ -1,4 +1,4 @@
-// Code generated by command: avogen -data ../data -output ztable.go godata. DO NOT EDIT.
+// Code generated by command: avogen -bootstrap -data ../data -output ztable.go godata. DO NOT EDIT.
 
 package inst
 

internal/inst/ztable_test.go

@@ -1,4 +1,4 @@
-// Code generated by command: avogen -data ../data -output ztable_test.go godatatest. DO NOT EDIT.
+// Code generated by command: avogen -bootstrap -data ../data -output ztable_test.go godatatest. DO NOT EDIT.
 
 package inst_test