446 lines
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446 lines
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<title>GNU Compiler Collection (GCC) Internals: Option properties</title>
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<link href="Option-Index.html#Option-Index" rel="index" title="Option Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Options.html#Options" rel="up" title="Options">
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<link href="Passes.html#Passes" rel="next" title="Passes">
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<a name="Option-properties"></a>
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<div class="header">
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<p>
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Previous: <a href="Option-file-format.html#Option-file-format" accesskey="p" rel="prev">Option file format</a>, Up: <a href="Options.html#Options" accesskey="u" rel="up">Options</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="Option-properties-1"></a>
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<h3 class="section">8.2 Option properties</h3>
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<p>The second field of an option record can specify any of the following
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properties. When an option takes an argument, it is enclosed in parentheses
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following the option property name. The parser that handles option files
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is quite simplistic, and will be tricked by any nested parentheses within
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the argument text itself; in this case, the entire option argument can
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be wrapped in curly braces within the parentheses to demarcate it, e.g.:
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</p>
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<div class="smallexample">
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<pre class="smallexample">Condition({defined (USE_CYGWIN_LIBSTDCXX_WRAPPERS)})
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</pre></div>
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<dl compact="compact">
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<dt><code>Common</code></dt>
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<dd><p>The option is available for all languages and targets.
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</p>
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</dd>
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<dt><code>Target</code></dt>
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<dd><p>The option is available for all languages but is target-specific.
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</p>
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</dd>
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<dt><code>Driver</code></dt>
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<dd><p>The option is handled by the compiler driver using code not shared
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with the compilers proper (<samp>cc1</samp> etc.).
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</p>
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</dd>
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<dt><code><var>language</var></code></dt>
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<dd><p>The option is available when compiling for the given language.
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</p>
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<p>It is possible to specify several different languages for the same
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option. Each <var>language</var> must have been declared by an earlier
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<code>Language</code> record. See <a href="Option-file-format.html#Option-file-format">Option file format</a>.
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</p>
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</dd>
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<dt><code>RejectDriver</code></dt>
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<dd><p>The option is only handled by the compilers proper (<samp>cc1</samp> etc.)
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and should not be accepted by the driver.
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</p>
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</dd>
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<dt><code>RejectNegative</code></dt>
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<dd><p>The option does not have a “no-” form. All options beginning with
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“f”, “W” or “m” are assumed to have a “no-” form unless this
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property is used.
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</p>
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</dd>
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<dt><code>Negative(<var>othername</var>)</code></dt>
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<dd><p>The option will turn off another option <var>othername</var>, which is
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the option name with the leading “-” removed. This chain action will
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propagate through the <code>Negative</code> property of the option to be
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turned off.
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</p>
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<p>As a consequence, if you have a group of mutually-exclusive
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options, their <code>Negative</code> properties should form a circular chain.
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For example, if options <samp>-<var>a</var></samp>, <samp>-<var>b</var></samp> and
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<samp>-<var>c</var></samp> are mutually exclusive, their respective <code>Negative</code>
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properties should be ‘<samp>Negative(<var>b</var>)</samp>’, ‘<samp>Negative(<var>c</var>)</samp>’
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and ‘<samp>Negative(<var>a</var>)</samp>’.
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</p>
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</dd>
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<dt><code>Joined</code></dt>
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<dt><code>Separate</code></dt>
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<dd><p>The option takes a mandatory argument. <code>Joined</code> indicates
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that the option and argument can be included in the same <code>argv</code>
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entry (as with <code>-mflush-func=<var>name</var></code>, for example).
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<code>Separate</code> indicates that the option and argument can be
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separate <code>argv</code> entries (as with <code>-o</code>). An option is
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allowed to have both of these properties.
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</p>
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</dd>
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<dt><code>JoinedOrMissing</code></dt>
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<dd><p>The option takes an optional argument. If the argument is given,
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it will be part of the same <code>argv</code> entry as the option itself.
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</p>
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<p>This property cannot be used alongside <code>Joined</code> or <code>Separate</code>.
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</p>
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</dd>
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<dt><code>MissingArgError(<var>message</var>)</code></dt>
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<dd><p>For an option marked <code>Joined</code> or <code>Separate</code>, the message
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<var>message</var> will be used as an error message if the mandatory
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argument is missing; for options without <code>MissingArgError</code>, a
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generic error message is used. <var>message</var> should contain a single
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‘<samp>%qs</samp>’ format, which will be used to format the name of the option
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passed.
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</p>
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</dd>
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<dt><code>Args(<var>n</var>)</code></dt>
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<dd><p>For an option marked <code>Separate</code>, indicate that it takes <var>n</var>
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arguments. The default is 1.
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</p>
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</dd>
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<dt><code>UInteger</code></dt>
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<dd><p>The option’s argument is a non-negative integer. The option parser
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will check and convert the argument before passing it to the relevant
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option handler. <code>UInteger</code> should also be used on options like
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<code>-falign-loops</code> where both <code>-falign-loops</code> and
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<code>-falign-loops</code>=<var>n</var> are supported to make sure the saved
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options are given a full integer.
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</p>
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</dd>
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<dt><code>ToLower</code></dt>
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<dd><p>The option’s argument should be converted to lowercase as part of
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putting it in canonical form, and before comparing with the strings
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indicated by any <code>Enum</code> property.
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</p>
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</dd>
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<dt><code>NoDriverArg</code></dt>
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<dd><p>For an option marked <code>Separate</code>, the option only takes an
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argument in the compiler proper, not in the driver. This is for
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compatibility with existing options that are used both directly and
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via <samp>-Wp,</samp>; new options should not have this property.
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</p>
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</dd>
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<dt><code>Var(<var>var</var>)</code></dt>
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<dd><p>The state of this option should be stored in variable <var>var</var>
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(actually a macro for <code>global_options.x_<var>var</var></code>).
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The way that the state is stored depends on the type of option:
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</p>
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<ul>
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<li> If the option uses the <code>Mask</code> or <code>InverseMask</code> properties,
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<var>var</var> is the integer variable that contains the mask.
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</li><li> If the option is a normal on/off switch, <var>var</var> is an integer
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variable that is nonzero when the option is enabled. The options
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parser will set the variable to 1 when the positive form of the
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option is used and 0 when the “no-” form is used.
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</li><li> If the option takes an argument and has the <code>UInteger</code> property,
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<var>var</var> is an integer variable that stores the value of the argument.
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</li><li> If the option takes an argument and has the <code>Enum</code> property,
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<var>var</var> is a variable (type given in the <code>Type</code> property of the
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‘<samp>Enum</samp>’ record whose <code>Name</code> property has the same argument as
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the <code>Enum</code> property of this option) that stores the value of the
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argument.
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</li><li> If the option has the <code>Defer</code> property, <var>var</var> is a pointer to
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a <code>VEC(cl_deferred_option,heap)</code> that stores the option for later
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processing. (<var>var</var> is declared with type <code>void *</code> and needs
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to be cast to <code>VEC(cl_deferred_option,heap)</code> before use.)
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</li><li> Otherwise, if the option takes an argument, <var>var</var> is a pointer to
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the argument string. The pointer will be null if the argument is optional
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and wasn’t given.
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</li></ul>
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<p>The option-processing script will usually zero-initialize <var>var</var>.
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You can modify this behavior using <code>Init</code>.
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</p>
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</dd>
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<dt><code>Var(<var>var</var>, <var>set</var>)</code></dt>
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<dd><p>The option controls an integer variable <var>var</var> and is active when
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<var>var</var> equals <var>set</var>. The option parser will set <var>var</var> to
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<var>set</var> when the positive form of the option is used and <code>!<var>set</var></code>
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when the “no-” form is used.
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</p>
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<p><var>var</var> is declared in the same way as for the single-argument form
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described above.
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</p>
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</dd>
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<dt><code>Init(<var>value</var>)</code></dt>
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<dd><p>The variable specified by the <code>Var</code> property should be statically
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initialized to <var>value</var>. If more than one option using the same
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variable specifies <code>Init</code>, all must specify the same initializer.
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</p>
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</dd>
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<dt><code>Mask(<var>name</var>)</code></dt>
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<dd><p>The option is associated with a bit in the <code>target_flags</code>
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variable (see <a href="Run_002dtime-Target.html#Run_002dtime-Target">Run-time Target</a>) and is active when that bit is set.
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You may also specify <code>Var</code> to select a variable other than
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<code>target_flags</code>.
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</p>
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<p>The options-processing script will automatically allocate a unique bit
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for the option. If the option is attached to ‘<samp>target_flags</samp>’,
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the script will set the macro <code>MASK_<var>name</var></code> to the appropriate
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bitmask. It will also declare a <code>TARGET_<var>name</var></code> macro that has
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the value 1 when the option is active and 0 otherwise. If you use <code>Var</code>
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to attach the option to a different variable, the bitmask macro with be
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called <code>OPTION_MASK_<var>name</var></code>.
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</p>
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</dd>
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<dt><code>InverseMask(<var>othername</var>)</code></dt>
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<dt><code>InverseMask(<var>othername</var>, <var>thisname</var>)</code></dt>
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<dd><p>The option is the inverse of another option that has the
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<code>Mask(<var>othername</var>)</code> property. If <var>thisname</var> is given,
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the options-processing script will declare a <code>TARGET_<var>thisname</var></code>
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macro that is 1 when the option is active and 0 otherwise.
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</p>
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</dd>
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<dt><code>Enum(<var>name</var>)</code></dt>
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<dd><p>The option’s argument is a string from the set of strings associated
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with the corresponding ‘<samp>Enum</samp>’ record. The string is checked and
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converted to the integer specified in the corresponding
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‘<samp>EnumValue</samp>’ record before being passed to option handlers.
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</p>
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</dd>
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<dt><code>Defer</code></dt>
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<dd><p>The option should be stored in a vector, specified with <code>Var</code>,
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for later processing.
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</p>
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</dd>
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<dt><code>Alias(<var>opt</var>)</code></dt>
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<dt><code>Alias(<var>opt</var>, <var>arg</var>)</code></dt>
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<dt><code>Alias(<var>opt</var>, <var>posarg</var>, <var>negarg</var>)</code></dt>
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<dd><p>The option is an alias for <samp>-<var>opt</var></samp> (or the negative form
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of that option, depending on <code>NegativeAlias</code>). In the first form,
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any argument passed to the alias is considered to be passed to
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<samp>-<var>opt</var></samp>, and <samp>-<var>opt</var></samp> is considered to be
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negated if the alias is used in negated form. In the second form, the
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alias may not be negated or have an argument, and <var>posarg</var> is
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considered to be passed as an argument to <samp>-<var>opt</var></samp>. In the
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third form, the alias may not have an argument, if the alias is used
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in the positive form then <var>posarg</var> is considered to be passed to
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<samp>-<var>opt</var></samp>, and if the alias is used in the negative form
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then <var>negarg</var> is considered to be passed to <samp>-<var>opt</var></samp>.
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</p>
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<p>Aliases should not specify <code>Var</code> or <code>Mask</code> or
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<code>UInteger</code>. Aliases should normally specify the same languages
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as the target of the alias; the flags on the target will be used to
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determine any diagnostic for use of an option for the wrong language,
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while those on the alias will be used to identify what command-line
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text is the option and what text is any argument to that option.
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</p>
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<p>When an <code>Alias</code> definition is used for an option, driver specs do
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not need to handle it and no ‘<samp>OPT_</samp>’ enumeration value is defined
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for it; only the canonical form of the option will be seen in those
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places.
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</p>
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</dd>
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<dt><code>NegativeAlias</code></dt>
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<dd><p>For an option marked with <code>Alias(<var>opt</var>)</code>, the option is
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considered to be an alias for the positive form of <samp>-<var>opt</var></samp>
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if negated and for the negative form of <samp>-<var>opt</var></samp> if not
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negated. <code>NegativeAlias</code> may not be used with the forms of
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<code>Alias</code> taking more than one argument.
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</p>
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</dd>
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<dt><code>Ignore</code></dt>
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<dd><p>This option is ignored apart from printing any warning specified using
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<code>Warn</code>. The option will not be seen by specs and no ‘<samp>OPT_</samp>’
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enumeration value is defined for it.
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</p>
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</dd>
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<dt><code>SeparateAlias</code></dt>
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<dd><p>For an option marked with <code>Joined</code>, <code>Separate</code> and
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<code>Alias</code>, the option only acts as an alias when passed a separate
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argument; with a joined argument it acts as a normal option, with an
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‘<samp>OPT_</samp>’ enumeration value. This is for compatibility with the
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Java <samp>-d</samp> option and should not be used for new options.
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</p>
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</dd>
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<dt><code>Warn(<var>message</var>)</code></dt>
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<dd><p>If this option is used, output the warning <var>message</var>.
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<var>message</var> is a format string, either taking a single operand with
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a ‘<samp>%qs</samp>’ format which is the option name, or not taking any
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operands, which is passed to the ‘<samp>warning</samp>’ function. If an alias
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is marked <code>Warn</code>, the target of the alias must not also be marked
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<code>Warn</code>.
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</p>
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</dd>
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<dt><code>Report</code></dt>
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<dd><p>The state of the option should be printed by <samp>-fverbose-asm</samp>.
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</p>
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</dd>
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<dt><code>Warning</code></dt>
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<dd><p>This is a warning option and should be shown as such in
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<samp>--help</samp> output. This flag does not currently affect anything
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other than <samp>--help</samp>.
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</p>
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</dd>
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<dt><code>Optimization</code></dt>
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<dd><p>This is an optimization option. It should be shown as such in
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<samp>--help</samp> output, and any associated variable named using
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<code>Var</code> should be saved and restored when the optimization level is
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changed with <code>optimize</code> attributes.
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</p>
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</dd>
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<dt><code>Undocumented</code></dt>
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<dd><p>The option is deliberately missing documentation and should not
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be included in the <samp>--help</samp> output.
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</p>
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</dd>
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<dt><code>Condition(<var>cond</var>)</code></dt>
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<dd><p>The option should only be accepted if preprocessor condition
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<var>cond</var> is true. Note that any C declarations associated with the
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option will be present even if <var>cond</var> is false; <var>cond</var> simply
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controls whether the option is accepted and whether it is printed in
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the <samp>--help</samp> output.
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</p>
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</dd>
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<dt><code>Save</code></dt>
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<dd><p>Build the <code>cl_target_option</code> structure to hold a copy of the
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option, add the functions <code>cl_target_option_save</code> and
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<code>cl_target_option_restore</code> to save and restore the options.
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</p>
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</dd>
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<dt><code>SetByCombined</code></dt>
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<dd><p>The option may also be set by a combined option such as
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<samp>-ffast-math</samp>. This causes the <code>gcc_options</code> struct to
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have a field <code>frontend_set_<var>name</var></code>, where <code><var>name</var></code>
|
|
is the name of the field holding the value of this option (without the
|
|
leading <code>x_</code>). This gives the front end a way to indicate that
|
|
the value has been set explicitly and should not be changed by the
|
|
combined option. For example, some front ends use this to prevent
|
|
<samp>-ffast-math</samp> and <samp>-fno-fast-math</samp> from changing the
|
|
value of <samp>-fmath-errno</samp> for languages that do not use
|
|
<code>errno</code>.
|
|
</p>
|
|
</dd>
|
|
<dt><code>EnabledBy(<var>opt</var>)</code></dt>
|
|
<dt><code>EnabledBy(<var>opt</var> || <var>opt2</var>)</code></dt>
|
|
<dt><code>EnabledBy(<var>opt</var> && <var>opt2</var>)</code></dt>
|
|
<dd><p>If not explicitly set, the option is set to the value of
|
|
<samp>-<var>opt</var></samp>; multiple options can be given, separated by
|
|
<code>||</code>. The third form using <code>&&</code> specifies that the option is
|
|
only set if both <var>opt</var> and <var>opt2</var> are set. The options <var>opt</var>
|
|
and <var>opt2</var> must have the <code>Common</code> property; otherwise, use
|
|
<code>LangEnabledBy</code>.
|
|
</p>
|
|
</dd>
|
|
<dt><code>LangEnabledBy(<var>language</var>, <var>opt</var>)</code></dt>
|
|
<dt><code>LangEnabledBy(<var>language</var>, <var>opt</var>, <var>posarg</var>, <var>negarg</var>)</code></dt>
|
|
<dd><p>When compiling for the given language, the option is set to the value
|
|
of <samp>-<var>opt</var></samp>, if not explicitly set. <var>opt</var> can be also a list
|
|
of <code>||</code> separated options. In the second form, if
|
|
<var>opt</var> is used in the positive form then <var>posarg</var> is considered
|
|
to be passed to the option, and if <var>opt</var> is used in the negative
|
|
form then <var>negarg</var> is considered to be passed to the option. It
|
|
is possible to specify several different languages. Each
|
|
<var>language</var> must have been declared by an earlier <code>Language</code>
|
|
record. See <a href="Option-file-format.html#Option-file-format">Option file format</a>.
|
|
</p>
|
|
</dd>
|
|
<dt><code>NoDWARFRecord</code></dt>
|
|
<dd><p>The option is omitted from the producer string written by
|
|
<samp>-grecord-gcc-switches</samp>.
|
|
</p>
|
|
</dd>
|
|
<dt><code>PchIgnore</code></dt>
|
|
<dd><p>Even if this is a target option, this option will not be recorded / compared
|
|
to determine if a precompiled header file matches.
|
|
</p>
|
|
</dd>
|
|
<dt><code>CPP(<var>var</var>)</code></dt>
|
|
<dd><p>The state of this option should be kept in sync with the preprocessor
|
|
option <var>var</var>. If this property is set, then properties <code>Var</code>
|
|
and <code>Init</code> must be set as well.
|
|
</p>
|
|
</dd>
|
|
<dt><code>CppReason(<var>CPP_W_Enum</var>)</code></dt>
|
|
<dd><p>This warning option corresponds to <code>cpplib.h</code> warning reason code
|
|
<var>CPP_W_Enum</var>. This should only be used for warning options of the
|
|
C-family front-ends.
|
|
</p>
|
|
</dd>
|
|
</dl>
|
|
|
|
|
|
<hr>
|
|
<div class="header">
|
|
<p>
|
|
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