1 @c Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
2 @c This is part of the GCC manual.
3 @c For copying conditions, see the file gcc.texi.
6 @chapter Option specification files
7 @cindex option specification files
10 Most GCC command-line options are described by special option
11 definition files, the names of which conventionally end in
12 @code{.opt}. This chapter describes the format of these files.
15 * Option file format:: The general layout of the files
16 * Option properties:: Supported option properties
19 @node Option file format
20 @section Option file format
22 Option files are a simple list of records in which each field occupies
23 its own line and in which the records themselves are separated by
24 blank lines. Comments may appear on their own line anywhere within
25 the file and are preceded by semicolons. Whitespace is allowed before
28 The files can contain two types of record: language definitions and
31 A language definition record has two fields: the string
32 @samp{Language} and the name of the language. Once a language has
33 been declared in this way, it can be used as an option property.
34 @xref{Option properties}.
36 An option definition record has the following fields:
40 the name of the option, with the leading ``-'' removed
42 a space-separated list of option properties (@pxref{Option properties})
44 the help text to use for @option{--help} (omitted if the second field
45 contains the @code{Undocumented} property).
48 By default, all options beginning with ``f'', ``W'' or ``m'' are
49 implicitly assumed to take a ``no-'' form. This form should not be
50 listed separately. If an option beginning with one of these letters
51 does not have a ``no-'' form, you can use the @code{RejectNegative}
52 property to reject it.
54 The help text is automatically line-wrapped before being displayed.
55 Normally the name of the option is printed on the left-hand side of
56 the output and the help text is printed on the right. However, if the
57 help text contains a tab character, the text to the left of the tab is
58 used instead of the option's name and the text to the right of the
59 tab forms the help text. This allows you to elaborate on what type
60 of argument the option takes.
62 @node Option properties
63 @section Option properties
65 The second field of an option record can specify the following properties:
69 The option is available for all languages and targets.
72 The option is available for all languages but is target-specific.
75 The option is available when compiling for the given language.
77 It is possible to specify several different languages for the same
78 option. Each @var{language} must have been declared by an earlier
79 @code{Language} record. @xref{Option file format}.
82 The option does not have a ``no-'' form. All options beginning with
83 ``f'', ``W'' or ``m'' are assumed to have a ``no-'' form unless this
88 The option takes a mandatory argument. @code{Joined} indicates
89 that the option and argument can be included in the same @code{argv}
90 entry (as with @code{-mflush-func=@var{name}}, for example).
91 @code{Separate} indicates that the option and argument can be
92 separate @code{argv} entries (as with @code{-o}). An option is
93 allowed to have both of these properties.
96 The option takes an optional argument. If the argument is given,
97 it will be part of the same @code{argv} entry as the option itself.
99 This property cannot be used alongside @code{Joined} or @code{Separate}.
102 The option's argument is a non-negative integer. The option parser
103 will check and convert the argument before passing it to the relevant
107 The option controls an integer variable @var{var}. If the option has
108 the @code{UInteger} property, the option parser will set @var{var} to
109 the value of the user-specified argument. Otherwise the option is
110 assumed to be an on/off switch that is active when @var{var} is nonzero.
111 In this case, the option parser will set @var{var} to 1 when the positive
112 form of the option is used and 0 when the ``no-'' form is used.
114 The option-processing script will usually declare @var{var} in
115 @file{options.c} and leave it to be zero-initialized at start-up time.
116 You can modify this behavior using @code{VarExists} and @code{Init}.
118 @item Var(@var{var}, @var{set})
119 The option controls an integer variable @var{var} and is active when
120 @var{var} equals @var{set}. The option parser will set @var{var} to
121 @var{set} when the positive form of the option is used and @code{!@var{set}}
122 when the ``no-'' form is used.
124 @var{var} is declared in the same way as for the single-argument form
128 The variable specified by the @code{Var} property already exists.
129 No definition should be added to @file{options.c} in response to
132 You should use this property if an earlier option has already declared
133 the variable or if the variable is declared outside @file{options.c}.
135 @item Init(@var{value})
136 The variable specified by the @code{Var} property should be statically
137 initialized to @var{value}.
139 @item Mask(@var{name})
140 The option is associated with a bit in the @code{target_flags} variable
141 (@pxref{Run-time Target}) and is active when that bit is set.
143 The options-processing script will automatically allocate a unique
144 bit for the option and set the macro @code{MASK_@var{name}} to the
145 appropriate bitmask. It will also declare a @code{TARGET_@var{name}}
146 macro that has the value 1 when the option is active and 0 otherwise.
148 @item InverseMask(@var{othername})
149 @itemx InverseMask(@var{othername}, @var{thisname})
150 The option is the inverse of another option that has the
151 @code{Mask(@var{othername})} property. If @var{thisname} is given,
152 the options-processing script will declare a @code{TARGET_@var{thisname}}
153 macro that is 1 when the option is active and 0 otherwise.
156 The state of the option should be printed by @option{-fverbose-asm}.
159 The option is deliberately missing documentation and should not
160 be included in the @option{--help} output.