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author | kent <kent@cr.ie.u-ryukyu.ac.jp> |
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date | Fri, 17 Jul 2009 14:47:48 +0900 |
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1 @c Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008 | |
2 @c Free Software Foundation, Inc. | |
3 @c This is part of the GCC manual. | |
4 @c For copying conditions, see the file gcc.texi. | |
5 | |
6 @node Options | |
7 @chapter Option specification files | |
8 @cindex option specification files | |
9 @cindex @samp{optc-gen.awk} | |
10 | |
11 Most GCC command-line options are described by special option | |
12 definition files, the names of which conventionally end in | |
13 @code{.opt}. This chapter describes the format of these files. | |
14 | |
15 @menu | |
16 * Option file format:: The general layout of the files | |
17 * Option properties:: Supported option properties | |
18 @end menu | |
19 | |
20 @node Option file format | |
21 @section Option file format | |
22 | |
23 Option files are a simple list of records in which each field occupies | |
24 its own line and in which the records themselves are separated by | |
25 blank lines. Comments may appear on their own line anywhere within | |
26 the file and are preceded by semicolons. Whitespace is allowed before | |
27 the semicolon. | |
28 | |
29 The files can contain the following types of record: | |
30 | |
31 @itemize @bullet | |
32 @item | |
33 A language definition record. These records have two fields: the | |
34 string @samp{Language} and the name of the language. Once a language | |
35 has been declared in this way, it can be used as an option property. | |
36 @xref{Option properties}. | |
37 | |
38 @item | |
39 A target specific save record to save additional information. These | |
40 records have two fields: the string @samp{TargetSave}, and a | |
41 declaration type to go in the @code{cl_target_option} structure. | |
42 | |
43 @item | |
44 An option definition record. These records have the following fields: | |
45 @enumerate | |
46 @item | |
47 the name of the option, with the leading ``-'' removed | |
48 @item | |
49 a space-separated list of option properties (@pxref{Option properties}) | |
50 @item | |
51 the help text to use for @option{--help} (omitted if the second field | |
52 contains the @code{Undocumented} property). | |
53 @end enumerate | |
54 | |
55 By default, all options beginning with ``f'', ``W'' or ``m'' are | |
56 implicitly assumed to take a ``no-'' form. This form should not be | |
57 listed separately. If an option beginning with one of these letters | |
58 does not have a ``no-'' form, you can use the @code{RejectNegative} | |
59 property to reject it. | |
60 | |
61 The help text is automatically line-wrapped before being displayed. | |
62 Normally the name of the option is printed on the left-hand side of | |
63 the output and the help text is printed on the right. However, if the | |
64 help text contains a tab character, the text to the left of the tab is | |
65 used instead of the option's name and the text to the right of the | |
66 tab forms the help text. This allows you to elaborate on what type | |
67 of argument the option takes. | |
68 | |
69 @item | |
70 A target mask record. These records have one field of the form | |
71 @samp{Mask(@var{x})}. The options-processing script will automatically | |
72 allocate a bit in @code{target_flags} (@pxref{Run-time Target}) for | |
73 each mask name @var{x} and set the macro @code{MASK_@var{x}} to the | |
74 appropriate bitmask. It will also declare a @code{TARGET_@var{x}} | |
75 macro that has the value 1 when bit @code{MASK_@var{x}} is set and | |
76 0 otherwise. | |
77 | |
78 They are primarily intended to declare target masks that are not | |
79 associated with user options, either because these masks represent | |
80 internal switches or because the options are not available on all | |
81 configurations and yet the masks always need to be defined. | |
82 @end itemize | |
83 | |
84 @node Option properties | |
85 @section Option properties | |
86 | |
87 The second field of an option record can specify the following properties: | |
88 | |
89 @table @code | |
90 @item Common | |
91 The option is available for all languages and targets. | |
92 | |
93 @item Target | |
94 The option is available for all languages but is target-specific. | |
95 | |
96 @item @var{language} | |
97 The option is available when compiling for the given language. | |
98 | |
99 It is possible to specify several different languages for the same | |
100 option. Each @var{language} must have been declared by an earlier | |
101 @code{Language} record. @xref{Option file format}. | |
102 | |
103 @item RejectNegative | |
104 The option does not have a ``no-'' form. All options beginning with | |
105 ``f'', ``W'' or ``m'' are assumed to have a ``no-'' form unless this | |
106 property is used. | |
107 | |
108 @item Negative(@var{othername}) | |
109 The option will turn off another option @var{othername}, which is the | |
110 the option name with the leading ``-'' removed. This chain action will | |
111 propagate through the @code{Negative} property of the option to be | |
112 turned off. | |
113 | |
114 @item Joined | |
115 @itemx Separate | |
116 The option takes a mandatory argument. @code{Joined} indicates | |
117 that the option and argument can be included in the same @code{argv} | |
118 entry (as with @code{-mflush-func=@var{name}}, for example). | |
119 @code{Separate} indicates that the option and argument can be | |
120 separate @code{argv} entries (as with @code{-o}). An option is | |
121 allowed to have both of these properties. | |
122 | |
123 @item JoinedOrMissing | |
124 The option takes an optional argument. If the argument is given, | |
125 it will be part of the same @code{argv} entry as the option itself. | |
126 | |
127 This property cannot be used alongside @code{Joined} or @code{Separate}. | |
128 | |
129 @item UInteger | |
130 The option's argument is a non-negative integer. The option parser | |
131 will check and convert the argument before passing it to the relevant | |
132 option handler. @code{UInteger} should also be used on options like | |
133 @code{-falign-loops} where both @code{-falign-loops} and | |
134 @code{-falign-loops}=@var{n} are supported to make sure the saved | |
135 options are given a full integer. | |
136 | |
137 @item Var(@var{var}) | |
138 The state of this option should be stored in variable @var{var}. | |
139 The way that the state is stored depends on the type of option: | |
140 | |
141 @itemize @bullet | |
142 @item | |
143 If the option uses the @code{Mask} or @code{InverseMask} properties, | |
144 @var{var} is the integer variable that contains the mask. | |
145 | |
146 @item | |
147 If the option is a normal on/off switch, @var{var} is an integer | |
148 variable that is nonzero when the option is enabled. The options | |
149 parser will set the variable to 1 when the positive form of the | |
150 option is used and 0 when the ``no-'' form is used. | |
151 | |
152 @item | |
153 If the option takes an argument and has the @code{UInteger} property, | |
154 @var{var} is an integer variable that stores the value of the argument. | |
155 | |
156 @item | |
157 Otherwise, if the option takes an argument, @var{var} is a pointer to | |
158 the argument string. The pointer will be null if the argument is optional | |
159 and wasn't given. | |
160 @end itemize | |
161 | |
162 The option-processing script will usually declare @var{var} in | |
163 @file{options.c} and leave it to be zero-initialized at start-up time. | |
164 You can modify this behavior using @code{VarExists} and @code{Init}. | |
165 | |
166 @item Var(@var{var}, @var{set}) | |
167 The option controls an integer variable @var{var} and is active when | |
168 @var{var} equals @var{set}. The option parser will set @var{var} to | |
169 @var{set} when the positive form of the option is used and @code{!@var{set}} | |
170 when the ``no-'' form is used. | |
171 | |
172 @var{var} is declared in the same way as for the single-argument form | |
173 described above. | |
174 | |
175 @item VarExists | |
176 The variable specified by the @code{Var} property already exists. | |
177 No definition should be added to @file{options.c} in response to | |
178 this option record. | |
179 | |
180 You should use this property only if the variable is declared outside | |
181 @file{options.c}. | |
182 | |
183 @item Init(@var{value}) | |
184 The variable specified by the @code{Var} property should be statically | |
185 initialized to @var{value}. | |
186 | |
187 @item Mask(@var{name}) | |
188 The option is associated with a bit in the @code{target_flags} | |
189 variable (@pxref{Run-time Target}) and is active when that bit is set. | |
190 You may also specify @code{Var} to select a variable other than | |
191 @code{target_flags}. | |
192 | |
193 The options-processing script will automatically allocate a unique bit | |
194 for the option. If the option is attached to @samp{target_flags}, | |
195 the script will set the macro @code{MASK_@var{name}} to the appropriate | |
196 bitmask. It will also declare a @code{TARGET_@var{name}} macro that has | |
197 the value 1 when the option is active and 0 otherwise. If you use @code{Var} | |
198 to attach the option to a different variable, the associated macros are | |
199 called @code{OPTION_MASK_@var{name}} and @code{OPTION_@var{name}} respectively. | |
200 | |
201 You can disable automatic bit allocation using @code{MaskExists}. | |
202 | |
203 @item InverseMask(@var{othername}) | |
204 @itemx InverseMask(@var{othername}, @var{thisname}) | |
205 The option is the inverse of another option that has the | |
206 @code{Mask(@var{othername})} property. If @var{thisname} is given, | |
207 the options-processing script will declare a @code{TARGET_@var{thisname}} | |
208 macro that is 1 when the option is active and 0 otherwise. | |
209 | |
210 @item MaskExists | |
211 The mask specified by the @code{Mask} property already exists. | |
212 No @code{MASK} or @code{TARGET} definitions should be added to | |
213 @file{options.h} in response to this option record. | |
214 | |
215 The main purpose of this property is to support synonymous options. | |
216 The first option should use @samp{Mask(@var{name})} and the others | |
217 should use @samp{Mask(@var{name}) MaskExists}. | |
218 | |
219 @item Report | |
220 The state of the option should be printed by @option{-fverbose-asm}. | |
221 | |
222 @item Undocumented | |
223 The option is deliberately missing documentation and should not | |
224 be included in the @option{--help} output. | |
225 | |
226 @item Condition(@var{cond}) | |
227 The option should only be accepted if preprocessor condition | |
228 @var{cond} is true. Note that any C declarations associated with the | |
229 option will be present even if @var{cond} is false; @var{cond} simply | |
230 controls whether the option is accepted and whether it is printed in | |
231 the @option{--help} output. | |
232 | |
233 @item Save | |
234 Build the @code{cl_target_option} structure to hold a copy of the | |
235 option, add the functions @code{cl_target_option_save} and | |
236 @code{cl_target_option_restore} to save and restore the options. | |
237 @end table |