1 // Copyright 2015 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // Package flags implements top-level flags and the usage message for the assembler. 6 package flags 7 8 import ( 9 "flag" 10 "fmt" 11 "os" 12 "path/filepath" 13 "strings" 14 ) 15 16 var ( 17 Debug = flag.Bool("debug", false, "dump instructions as they are parsed") 18 OutputFile = flag.String("o", "", "output file; default foo.6 for /a/b/c/foo.s on amd64") 19 PrintOut = flag.Bool("S", false, "print assembly and machine code") 20 TrimPath = flag.String("trimpath", "", "remove prefix from recorded source file paths") 21 Shared = flag.Bool("shared", false, "generate code that can be linked into a shared library") 22 Dynlink = flag.Bool("dynlink", false, "support references to Go symbols defined in other shared libraries") 23 ) 24 25 var ( 26 D MultiFlag 27 I MultiFlag 28 ) 29 30 func init() { 31 flag.Var(&D, "D", "predefined symbol with optional simple value -D=identifer=value; can be set multiple times") 32 flag.Var(&I, "I", "include directory; can be set multiple times") 33 } 34 35 // MultiFlag allows setting a value multiple times to collect a list, as in -I=dir1 -I=dir2. 36 type MultiFlag []string 37 38 func (m *MultiFlag) String() string { 39 return fmt.Sprint(*m) 40 } 41 42 func (m *MultiFlag) Set(val string) error { 43 (*m) = append(*m, val) 44 return nil 45 } 46 47 func Usage() { 48 fmt.Fprintf(os.Stderr, "usage: asm [options] file.s\n") 49 fmt.Fprintf(os.Stderr, "Flags:\n") 50 flag.PrintDefaults() 51 os.Exit(2) 52 } 53 54 func Parse() { 55 flag.Usage = Usage 56 flag.Parse() 57 if flag.NArg() != 1 { 58 flag.Usage() 59 } 60 61 // Flag refinement. 62 if *OutputFile == "" { 63 input := filepath.Base(flag.Arg(0)) 64 if strings.HasSuffix(input, ".s") { 65 input = input[:len(input)-2] 66 } 67 *OutputFile = fmt.Sprintf("%s.o", input) 68 } 69 } 70
