--- /dev/null
+// Copyright 2015 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 ir
+
+// This file defines the BuilderMode type and its command-line flag.
+
+import (
+ "bytes"
+ "fmt"
+)
+
+// BuilderMode is a bitmask of options for diagnostics and checking.
+//
+// *BuilderMode satisfies the flag.Value interface. Example:
+//
+// var mode = ir.BuilderMode(0)
+// func init() { flag.Var(&mode, "build", ir.BuilderModeDoc) }
+//
+type BuilderMode uint
+
+const (
+ PrintPackages BuilderMode = 1 << iota // Print package inventory to stdout
+ PrintFunctions // Print function IR code to stdout
+ PrintSource // Print source code when printing function IR
+ LogSource // Log source locations as IR builder progresses
+ SanityCheckFunctions // Perform sanity checking of function bodies
+ NaiveForm // Build naïve IR form: don't replace local loads/stores with registers
+ GlobalDebug // Enable debug info for all packages
+)
+
+const BuilderModeDoc = `Options controlling the IR builder.
+The value is a sequence of zero or more of these letters:
+C perform sanity [C]hecking of the IR form.
+D include [D]ebug info for every function.
+P print [P]ackage inventory.
+F print [F]unction IR code.
+A print [A]ST nodes responsible for IR instructions
+S log [S]ource locations as IR builder progresses.
+N build [N]aive IR form: don't replace local loads/stores with registers.
+`
+
+func (m BuilderMode) String() string {
+ var buf bytes.Buffer
+ if m&GlobalDebug != 0 {
+ buf.WriteByte('D')
+ }
+ if m&PrintPackages != 0 {
+ buf.WriteByte('P')
+ }
+ if m&PrintFunctions != 0 {
+ buf.WriteByte('F')
+ }
+ if m&PrintSource != 0 {
+ buf.WriteByte('A')
+ }
+ if m&LogSource != 0 {
+ buf.WriteByte('S')
+ }
+ if m&SanityCheckFunctions != 0 {
+ buf.WriteByte('C')
+ }
+ if m&NaiveForm != 0 {
+ buf.WriteByte('N')
+ }
+ return buf.String()
+}
+
+// Set parses the flag characters in s and updates *m.
+func (m *BuilderMode) Set(s string) error {
+ var mode BuilderMode
+ for _, c := range s {
+ switch c {
+ case 'D':
+ mode |= GlobalDebug
+ case 'P':
+ mode |= PrintPackages
+ case 'F':
+ mode |= PrintFunctions
+ case 'A':
+ mode |= PrintSource
+ case 'S':
+ mode |= LogSource
+ case 'C':
+ mode |= SanityCheckFunctions
+ case 'N':
+ mode |= NaiveForm
+ default:
+ return fmt.Errorf("unknown BuilderMode option: %q", c)
+ }
+ }
+ *m = mode
+ return nil
+}
+
+// Get returns m.
+func (m BuilderMode) Get() interface{} { return m }