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 "cmd/internal/objabi" 10 "flag" 11 "fmt" 12 "os" 13 "path/filepath" 14 "strings" 15 ) 16 17 var ( 18 Debug = flag.Bool("debug", false, "dump instructions as they are parsed") 19 OutputFile = flag.String("o", "", "output file; default foo.o for /a/b/c/foo.s as first argument") 20 PrintOut = flag.Bool("S", false, "print assembly and machine code") 21 TrimPath = flag.String("trimpath", "", "remove prefix from recorded source file paths") 22 Shared = flag.Bool("shared", false, "generate code that can be linked into a shared library") 23 Dynlink = flag.Bool("dynlink", false, "support references to Go symbols defined in other shared libraries") 24 AllErrors = flag.Bool("e", false, "no limit on number of errors reported") 25 SymABIs = flag.Bool("gensymabis", false, "write symbol ABI information to output file, don't assemble") 26 ) 27 28 var ( 29 D MultiFlag 30 I MultiFlag 31 ) 32 33 func init() { 34 flag.Var(&D, "D", "predefined symbol with optional simple value -D=identifier=value; can be set multiple times") 35 flag.Var(&I, "I", "include directory; can be set multiple times") 36 objabi.AddVersionFlag() // -V 37 } 38 39 // MultiFlag allows setting a value multiple times to collect a list, as in -I=dir1 -I=dir2. 40 type MultiFlag []string 41 42 func (m *MultiFlag) String() string { 43 if len(*m) == 0 { 44 return "" 45 } 46 return fmt.Sprint(*m) 47 } 48 49 func (m *MultiFlag) Set(val string) error { 50 (*m) = append(*m, val) 51 return nil 52 } 53 54 func Usage() { 55 fmt.Fprintf(os.Stderr, "usage: asm [options] file.s ...\n") 56 fmt.Fprintf(os.Stderr, "Flags:\n") 57 flag.PrintDefaults() 58 os.Exit(2) 59 } 60 61 func Parse() { 62 flag.Usage = Usage 63 flag.Parse() 64 if flag.NArg() == 0 { 65 flag.Usage() 66 } 67 68 // Flag refinement. 69 if *OutputFile == "" { 70 if flag.NArg() != 1 { 71 flag.Usage() 72 } 73 input := filepath.Base(flag.Arg(0)) 74 if strings.HasSuffix(input, ".s") { 75 input = input[:len(input)-2] 76 } 77 *OutputFile = fmt.Sprintf("%s.o", input) 78 } 79 } 80
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