GNU Compiler Collection (GCC) 4.2 Internals

7.2 Option properties

The second field of an option record can specify the following properties:

Common

The option is available for all languages and targets.

Target

The option is available for all languages but is target-specific.

language

The option is available when compiling for the given language.

It is possible to specify several different languages for the same option. Each language must have been declared by an earlier Language record. See Option file format.

RejectNegative

The option does not have a “no-” form. All options beginning with “f”, “W” or “m” are assumed to have a “no-” form unless this property is used.

Negative(othername)

The option will turn off another option othername, which is the the option name with the leading “-” removed. This chain action will propagate through the Negative property of the option to be turned off.

Joined

Separate

The option takes a mandatory argument. Joined indicates that the option and argument can be included in the same argv entry (as with -mflush-func=name, for example). Separate indicates that the option and argument can be separate argv entries (as with -o). An option is allowed to have both of these properties.

JoinedOrMissing

The option takes an optional argument. If the argument is given, it will be part of the same argv entry as the option itself.

This property cannot be used alongside Joined or Separate.

UInteger

The option's argument is a non-negative integer. The option parser will check and convert the argument before passing it to the relevant option handler.

Var(var)

The state of this option should be stored in variable var. The way that the state is stored depends on the type of option:

• If the option uses the Mask or InverseMask properties, var is the integer variable that contains the mask.
• If the option is a normal on/off switch, var is an integer variable that is nonzero when the option is enabled. The options parser will set the variable to 1 when the positive form of the option is used and 0 when the “no-” form is used.
• If the option takes an argument and has the UInteger property, var is an integer variable that stores the value of the argument.
• Otherwise, if the option takes an argument, var is a pointer to the argument string. The pointer will be null if the argument is optional and wasn't given.

The option-processing script will usually declare var in options.c and leave it to be zero-initialized at start-up time. You can modify this behavior using VarExists and Init.

Var(var, set)

The option controls an integer variable var and is active when var equals set. The option parser will set var to set when the positive form of the option is used and !set when the “no-” form is used.

var is declared in the same way as for the single-argument form described above.

VarExists

The variable specified by the Var property already exists. No definition should be added to options.c in response to this option record.

You should use this property only if the variable is declared outside options.c.

Init(value)

The variable specified by the Var property should be statically initialized to value.

Mask(name)

The option is associated with a bit in the target_flags variable (see Run-time Target) and is active when that bit is set. You may also specify Var to select a variable other than target_flags.

The options-processing script will automatically allocate a unique bit for the option. If the option is attached to `target_flags', the script will set the macro MASK_name to the appropriate bitmask. It will also declare a TARGET_name macro that has the value 1 when the option is active and 0 otherwise. If you use Var to attach the option to a different variable, the associated macros are called OPTION_MASK_name and OPTION_name respectively.

You can disable automatic bit allocation using MaskExists.

InverseMask(othername)

InverseMask(othername, thisname)

The option is the inverse of another option that has the Mask(othername) property. If thisname is given, the options-processing script will declare a TARGET_thisname macro that is 1 when the option is active and 0 otherwise.

MaskExists

The mask specified by the Mask property already exists. No MASK or TARGET definitions should be added to options.h in response to this option record.

The main purpose of this property is to support synonymous options. The first option should use `Mask(name)' and the others should use `Mask(name) MaskExists'.

Report

The state of the option should be printed by -fverbose-asm.

Undocumented

The option is deliberately missing documentation and should not be included in the --help output.

Condition(cond)

The option should only be accepted if preprocessor condition cond is true. Note that any C declarations associated with the option will be present even if cond is false; cond simply controls whether the option is accepted and whether it is printed in the --help output.